Gynecology_Novak

Gynecology_Novak. For minor surgical stress, such as colonoscopy, the glucocorticoid target is approximately 25 mg of hydrocortisone equivalent on the day of the procedure (173). For moderate surgical stress, for example, open cholecystectomy, the glucocorticoid target is 50 to 75 mg of hydrocortisone equivalent on the day of the procedure and tapered quickly for 1 to 2 days (173). The patient should receive her normal daily dose preoperatively, followed by 50 mg of hydrocortisone intravenously administered intraoperatively. For major surgical stress, such as liver resection, the glucocorticoid target range is 100 to 150 mg hydrocortisone equivalent on the day of the procedure, tapering rapidly over the next 1 to 2 days to the usual dosage (173). The patient should receive her normal daily dose preoperatively.


Gynecology_Novak

Gynecology_Novak. Administration of high-dose steroids should be stopped as soon as possible postoperatively because they can inhibit wound healing and promote infection. Hypertension and glucose intolerance can develop. When a prolonged or involved procedure is performed and longer steroid use is necessary, careful tapering may be required. The previously recommended approach was to halve the dose of hydrocortisone on a daily basis until a dose of 25 mg is reached. Eliminating one daily dose each day until the drug is stopped was considered the safest method of withdrawal; no consensus on the timing or duration of steroid tapering exists. Addison’s disease is uncommon but should be considered in the differential diagnosis if the patient develops perioperative hypotension after steroids are withdrawn. In addition to blood and isotonic ﬂuid replacement, a “stress” dose of steroids should be given if adrenal insufficiency is suspected and sepsis and hypovolemia are excluded.


Gynecology_Novak

Gynecology_Novak. Cardiovascular Diseases The incidence of perioperative cardiovascular complications decreased markedly as a result of improvements in preoperative detection of high-risk patients, preoperative preparation, and surgical and anesthetic techniques (174).


Gynecology_Novak

Gynecology_Novak. Preoperative Evaluation The goal of a preoperative cardiac evaluation is to determine the presence of heart disease, its severity, and the potential risk to the patient during the perioperative period. Every patient should be questioned about symptoms of cardiac disease including chest pain, dyspnea on exertion, peripheral edema, wheezing, syncope, claudication, or palpitations. Patients with a history of cardiac disease should be evaluated for worsening of symptoms, which indicates progressive or poorly controlled disease. Records of previous treatment should be obtained. Prescriptions for antihypertensive, anticoagulant, antiarrhythmic, antilipid, or antianginal medications may be the only indication of cardiac problems. In patients without known heart disease, the presence of DM, hyperlipidemia, hypertension, tobacco use, or a family history of heart disease identifies patients at higher risk for heart disease who should be more carefully screened.


Gynecology_Novak

Gynecology_Novak. On physical examination, the presence of findings such as hypertension, jugular venous distention, laterally displaced point of maximum impulse, irregular pulse, third heart sound, pulmonary rales, heart murmurs, peripheral edema, or vascular bruits should prompt a more complete evaluation. Laboratory evaluation of patients with known or suspected heart disease should include a blood count and serum chemistry analysis. Patients with heart disease tolerate anemia poorly. Serum sodium and potassium levels are particularly important in patients taking diuretics and digitalis. Blood urea nitrogen and creatinine values provide information on renal function and hydration status. Assessment of blood glucose levels may detect undiagnosed DM. Chest radiography and electrocardiography are mandatory as part of the preoperative evaluation, and the results may be particularly helpful when compared with those of previous studies.


Gynecology_Novak

Gynecology_Novak. Coronary Artery Disease Coronary artery disease is a major risk factor for patients undergoing abdominal surgery. In an adult population without a prior history of myocardial infarction, the incidence of myocardial infarction following surgery is 0.1% to 0.7% (175). In patients who had a prior myocardial infarction, the reinfarction rate is 2.8% to 7% (176). The risk of reinfarction is inversely proportional to the length of time between infarction and surgery. At 3 months or less, the risk of reinfarction is 5.7%, and from 3 to 6 months, the rate falls to 2.3%. Six months after myocardial infarction, the reinfarction rate is 1.5% (175). Careful perioperative management can lower the reinfarction rate in patients who had recent infarctions. Perioperative myocardial infarction is associated with a mortality rate of 26% to 70% (177).


Gynecology_Novak

Gynecology_Novak. Because of the high mortality and morbidity associated with perioperative myocardial infarction, considerable effort is made to predict perioperative cardiac risk. A prospective evaluation of preoperative cardiac risk factors using a multivariate analysis identified independent cardiac risk factors for patients undergoing noncardiac surgery (177). Using these factors, a cardiac risk index was created that placed a patient in one of four risk classes. This cardiac risk index was further modified and validated prospectively, resulting in a tool for clinical risk assessment in nonemergent major noncardiac surgery, the Revised Cardiac Risk Index (178). Risk factors include high-risk surgical procedures, history of ischemic heart disease, history of congestive heart failure, history of transient ischemic attack or stroke, preoperative insulin therapy, and preoperative serum creatinine levels greater than 2.0 mg/dL. Depending on the number of risk factors, the risk of major cardiac events


Gynecology_Novak

Gynecology_Novak. ischemic attack or stroke, preoperative insulin therapy, and preoperative serum creatinine levels greater than 2.0 mg/dL. Depending on the number of risk factors, the risk of major cardiac events (myocardial infarction, cardiac arrest, pulmonary edema, and complete heart block) range from 0.5% to 9.1% (Table 22.14).


Gynecology_Novak

Gynecology_Novak. Risk assessment is stratified into three major categories: (i) clinical predictors, (ii) functional capacity, and (iii) surgery-specific risk (179). Clinical predictors of increased perioperative Table 22.14 Major Cardiac Event Rates by the Revised Cardiac Risk Index CI, confidence interval. Adapted from Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999;100: 1043–1049.


Gynecology_Novak

Gynecology_Novak. cardiac risk were formerly divided into major, intermediate, and minor factors. The intermediate category was replaced by clinical risk factors from the revised cardiac risk index (Table 22.15). The patient’s functional status is assessed by a thorough history (Table 22.16), and self-reported exercise tolerance can be used to predict perioperative risk, based on a system of metabolic equivalents (METS) (180). Surgery-specific risk is subdivided into high-risk procedures (emergent major operations, aortic and vascular procedures, and prolonged surgical procedures associated with large ﬂuid shifts or blood loss), intermediate-risk procedures (intraperitoneal and intrathoracic), and low-risk procedures (endoscopic, breast surgery, and ambulatory procedures). Patients with poor functional capacity and any clinical risk factor undergoing more than low-risk nonemergent surgery should undergo preoperative testing, based on American Heart Association (AHA) guidelines (179).


Gynecology_Novak

Gynecology_Novak. In an effort to quantify preoperative cardiac risk, several tests are used to assess cardiovascular function. Electrocardiogram should be considered for anyone other than asymptomatic persons undergoing low risk procedures. Echocardiography may be used to evaluate left ventricular function (179). Patients who have dyspnea of unknown origin, current or past heart failure, Table 22.15 Clinical Predictors of Increased Perioperative Cardiovascular Risk Unstable coronary syndromes: acute (≤7 days) or recent (7 < days ≤ 1 month) MI, unstable or severe angina Decompensated congestive heart failure Significant arrhythmias (high-grade AV block, symptomatic ventricular arrhythmias, supraventricular arrhythmias with uncontrolled ventricular rate) Severe valvular disease History of cerebrovascular disease Prior ischemic cardiac disease Compensated or prior congestive heart failure Diabetes mellitus Renal insufficiency


Gynecology_Novak

Gynecology_Novak. History of cerebrovascular disease Prior ischemic cardiac disease Compensated or prior congestive heart failure Diabetes mellitus Renal insufficiency Advanced age Abnormal ECG (LVH, LBBB, ST-T abnormalities) Rhythm other than sinus Uncontrolled systemic hypertension MI, myocardial infarction; AV, atrioventricular; ECG, electrocardiogram; LVH, left ventricular hypertrophy; LBBB, left bundle branch block. Adapted from Fleisher LA, Beckman JA, Brown KA, et al. 2009 ACCF/AHA focused update on perioperative beta blockade incorporated into the ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2009;120:e169–e276. Table 22.16 Functional Capacity Assessment from Clinical History


Gynecology_Novak

Gynecology_Novak. Table 22.16 Functional Capacity Assessment from Clinical History Carry 24 lb up eight steps Carry objects that weigh 80 lb Outdoor work (shovel snow, spade soil) Recreation (ski, basketball, squash, handball, jog, or walk 5 mph) Have sexual intercourse without stopping Walk at 4 mph on ground level Outdoor work (garden, rake, weed) Recreation (roller-skate, dance) Shower and dress without stopping Basic housework Walk 2.5 mph on level ground Recreation (golf, bowl) Adapted from Mehta RH, Bossone E, Eagle KA. Perioperative cardiac risk assessment for noncardiac surgery. Cardiologia 1999;44:409–418. prior cardiomyopathy, or with any of the above factors and no cardiac assessment in the past 12 months should consider echocardiogram testing preoperatively (179). Exercise stress testing before surgery can identify patients who have ischemic heart disease not apparent at rest.


Gynecology_Novak

Gynecology_Novak. AHA guidelines recommend noninvasive stress testing for patients with one to two clinical risk factors, undergoing intermediate risk surgery with poor functional capacity of METS less than 4. Likewise, it is recommended for patients with greater clinical risk factors or those undergoing high-risk surgery (179). These patients are at increased risk of developing cardiac complications in the perioperative period. In a study of patients undergoing peripheral vascular surgery, a high-risk group of patients was identified who had ischemic electrocardiographic changes when they exercised to less than 75% of their maximal predicted heart rate. In this group, the incidence of perioperative myocardial infarction was 25% and the overall cardiac mortality rate was 18.5%. Conversely, no perioperative infarctions occurred in patients who were able to exercise to more than 75% of their maximal predicted heart rate and who had no electrocardiographic evidence of ischemia (181). The prognostic value


Gynecology_Novak

Gynecology_Novak. infarctions occurred in patients who were able to exercise to more than 75% of their maximal predicted heart rate and who had no electrocardiographic evidence of ischemia (181). The prognostic value of stress testing was not supported in another prospective study that found that only an abnormal preoperative resting electrocardiography result was an independent risk factor (182). The exercise stress test must be selectively applied to a high-risk population because its predictive value depends on the prevalence of the disease. It is not prudent to screen all patients preoperatively; it is preferable to rely on a careful history to identify patients with symptoms of cardiac disease for whom the test would be most predictive.


Gynecology_Novak

Gynecology_Novak. Exercise stress testing is limited in some patients who cannot exercise because of musculoskeletal disease, pulmonary disease, or severe cardiac disease. Dipyridamole-thallium scanning may be used to overcome the limitations of exercise stress testing. This study has a high degree of sensitivity and specificity but a low positive predictive value (179,183). It relies on the ability of dipyridamole to dilate normal coronary arteries but not stenotic vessels. Normally perfused myocardium readily takes up thallium when it is given intravenously. Conversely, hypoperfused myocardium does not show good uptake of thallium when scanned 5 minutes after injection. Reperfusion and uptake of thallium 3 hours after injection identify viable but high-risk myocardium. Old infarctions are identified as areas without uptake. Several studies show an increasing risk of perioperative myocardial infarction dependent on the extent of reperfusion of thallium, or reversible defect, ranging from 3% to 49%


Gynecology_Novak

Gynecology_Novak. areas without uptake. Several studies show an increasing risk of perioperative myocardial infarction dependent on the extent of reperfusion of thallium, or reversible defect, ranging from 3% to 49% (184,185). The dipyridamole-thallium scan is applicable to clinically high-risk patients who are unable to exercise because it uses a medically induced “stress.”


Gynecology_Novak

Gynecology_Novak. Dobutamine stress echocardiography is another test to evaluate cardiac risk in patients who are unable to exercise. This method identifies regional cardiac wall motion abnormalities after dobutamine infusion to identify patients at high risk for cardiac events. Positive and negative predictive values are similar to those of dipyridamole-thallium testing for a perioperative event (186,187). Dipyridamole-thallium testing is preferred for patients with known cardiac arrhythmias, and dobutamine is preferred for patients with bronchospastic lung disease and in those with severe cardiac stenosis (188). Coronary angiography should be considered only in patients who have an indication for angiography independent of the planned surgery, such as patients with acute coronary syndromes, unstable angina, angina refractory to medical therapy, or high-risk results on noninvasive testing.


Gynecology_Novak

Gynecology_Novak. Preoperative testing should be used discriminately in intermediate-risk patients. Controversy exists regarding the accuracy of these tests to provide prognostic information beyond what is obtained from clinical risk stratification for nonvascular procedures. Diagnostic testing should not lead to unnecessary additional testing or harmful delays in surgery. The American College of Cardiology and the American Heart Association present an updated detailed algorithm that incorporates risk-factor stratification to guide clinicians to proceed directly to surgery, to delay surgery and obtain preoperative noninvasive testing, or to attempt risk factor modification (179).


Gynecology_Novak

Gynecology_Novak. It is rare for patients who are younger than 50 years and who do not have diabetes, hypertension, hypercholesterolemia, or coronary artery disease to suffer a perioperative myocardial infarction. In contrast, patients with coronary artery disease are at increased risk of myocardial infarction in the postoperative period. Prevention, early recognition, and treatment are important because myocardial infarctions that occur in the postoperative period have mortality rates of up to 25% and are associated with increased rates of cardiovascular death in the 6 months following surgery (189).


Gynecology_Novak

Gynecology_Novak. Nearly two-thirds of postoperative myocardial infarctions occur during the first 3 days postoperatively (189). Although the pathophysiologic factors are complex, the causes of postoperative myocardial ischemia and infarction are related to decreased myocardial oxygen supply coupled with increased myocardial oxygen requirements. In postoperative patients, conditions that decrease oxygen supply to the myocardium include tachycardia, increased preload, hypotension, anemia, and hypoxia (190). Conditions that increase myocardial oxygen consumption are tachycardia, increased preload, increased afterload, and increased contractility. Tachycardia and increased preload are the most important causes of ischemia, because both conditions decrease oxygen supply to the myocardium while simultaneously increasing myocardial oxygen demand. Tachycardia decreases the diastolic time, which, when the coronary arteries are perfused, decreases the volume of oxygen available to the myocardium. Increased


Gynecology_Novak

Gynecology_Novak. increasing myocardial oxygen demand. Tachycardia decreases the diastolic time, which, when the coronary arteries are perfused, decreases the volume of oxygen available to the myocardium. Increased preload increases the pressure exerted by the myocardial wall on the arterioles within it, thus decreasing myocardial blood ﬂow.


Gynecology_Novak

Gynecology_Novak. Other factors associated with perioperative myocardial ischemia include physiologic responses to the stress of intubation, intravenous or arterial line placement, emergence from anesthesia, pain, and anxiety. These stresses result in catecholamine stimulation of the cardiovascular system, resulting in increased heart rate, blood pressure, and contractility, which may induce or worsen myocardial ischemia. Loss of intravascular volume because of third spacing of ﬂuids or postoperative hemorrhage can induce ischemia.


Gynecology_Novak

Gynecology_Novak. Postoperative myocardial infarction is often difficult to diagnose. Chest pain, which is present in 90% of nonsurgical patients with myocardial infarction, may be present in only 50% of patients with postoperative infarction because myocardial pain may be masked by coexisting surgical pain and the use of analgesics (175). It is important to maintain a high level of suspicion for postoperative infarction in patients with coronary artery disease. The presence of arrhythmia, congestive heart failure, hypotension, dyspnea, or elevations of pulmonary artery pressure may indicate infarction and should prompt a thorough cardiac investigation and electrocardiographic monitoring. Measurement of creatinine phosphokinase myocardial band (CPK-MB) isoenzyme and troponin T levels are the most sensitive and specific indicators of myocardial infarction, and assessments should be obtained for all patients suspected of myocardial infarction (189).


Gynecology_Novak

Gynecology_Novak. Despite the high incidence of silent myocardial infarction, routine use of postoperative electrocardiography (ECG) for all patients with cardiovascular disease is controversial.


Gynecology_Novak

Gynecology_Novak. Many patients will exhibit P-wave changes that spontaneously resolve and do not represent ischemia or infarction. Conversely, patients with proven myocardial infarctions may show few, if any, ECG abnormalities. The American College of Cardiology and American Heart Association advise consideration of postoperative surveillance via ST-segment monitoring for myocardial infarction in patients with known or suspected coronary artery disease (191). In a review of over 2,400 patients, the sensitivity of predicting postoperative cardiac events was 55% to 100%, specificity 37% to 85%, positive predictive value 7% to 57%, and negative predictive value 89% to 100% (192). If routine screening of asymptomatic patients is desired, ECG should be performed 24 hours following surgery because significant ECG changes that occur immediately postoperatively will persist for 24 hours. It is prudent to continue serial ECG assessments for at least 3 days postoperatively.


Gynecology_Novak

Gynecology_Novak. Postoperative management of patients with coronary artery disease is based on maximizing delivery of oxygen to the myocardium and decreasing myocardial oxygen utilization. Most patients benefit from supplemental oxygen in the postoperative period, although special care should be exercised in patients with COPD. Oxygenation can easily be monitored by pulse oximetry. Anemia is detrimental because of loss of oxygen-carrying capacity and resultant tachycardia and should, therefore, be carefully corrected in high-risk patients. Although transfusion criteria are not absolute, all patients with a hemoglobin less than 6 mg/dL, and hemoglobin of 6 to 10 mg/dL with significant cardiac risk factors should be offered blood transfusion (193).


Gynecology_Novak

Gynecology_Novak. Patients with coronary artery disease may benefit from pharmacologic control of hyperadrenergic states that result from increased postoperative catecholamine production. Beta-blockers decrease heart rate, myocardial contractility, and systemic blood pressure, all of which are increased by adrenergic stimulation. Perioperative use of β1 selective beta-blocker is shown to significantly reduce perioperative ischemia, myocardial infarction, and overall mortality caused by cardiac death and congestive heart failure in the perioperative period (194–196). The POISE (Perioperative Ischemic Evaluation) trial, a randomized controlled trial of metoprolol, enrolling 8,000 patients undergoing noncardiac surgery, revealed a reduction in cardiovascular death, myocardial infarction, and cardiac arrest. There was an increased risk of stroke and total mortality (197). The AHA provides the following guidelines: Continue beta-blocker therapy in patients on baseline beta-blockers for treatment of cardiac


Gynecology_Novak

Gynecology_Novak. was an increased risk of stroke and total mortality (197). The AHA provides the following guidelines: Continue beta-blocker therapy in patients on baseline beta-blockers for treatment of cardiac disease. Consider initiating and titrating beta-blockers in patients with coronary artery disease or high cardiac risk (as defined by the presence of more than one clinical risk factor) who are undergoing intermediate-risk surgery (155). Therapy should be initiated at least 1 week before surgery to allow for proper titration. The timing and optimal duration of beta-blocker therapy remains an area of uncertainty. Nevertheless, for patients already on beta-blocker therapy, they should continue it perioperatively because abrupt withdrawal results in a rebound hyperadrenergic state.


Gynecology_Novak

Gynecology_Novak. Prophylactic use of other agents such as nitroglycerin and calcium-channel blockers remains controversial, as data did not show a consistent benefit toward reducing risk of ischemic cardiac events. Nitroglycerin may cause hypotension, which may worsen cardiac status (155). Congestive Heart Failure Patients with congestive heart failure (CHF) face a substantially increased risk of myocardial infarction during and after surgery (177). The postoperative development of pulmonary edema may be associated with a high mortality rate, especially if it occurs in the setting of cardiac ischemia (198,199). Because patients with heart failure at the time of surgery are significantly more likely to develop complications, every effort should be made to diagnose and treat CHF before surgery (178,200). The signs and symptoms of CHF are listed in Table 22.17 and should be assessed based on preoperative history and physical examination. Patients who are able to


Gynecology_Novak

Gynecology_Novak. Table 22.17 Signs and Symptoms of Congestive Heart Failure 1. Presence of an S3 gallop 2. 3. Lateral shift of the point of maximal impulse 4. 5. 6. 7. Evidence of pulmonary edema or cardiac enlargement on chest radiograph 8. perform usual daily activities without developing CHF are at limited risk of perioperative heart failure. To prevent severe postoperative complications, CHF must be corrected preoperatively.


Gynecology_Novak

Gynecology_Novak. perform usual daily activities without developing CHF are at limited risk of perioperative heart failure. To prevent severe postoperative complications, CHF must be corrected preoperatively. Treatment usually relies on aggressive diuretic therapy, although care must be taken to avoid dehydration, which may result in hypotension during the induction of anesthesia. Hypokalemia can result from diuretic therapy and is especially deleterious to patients who are taking digitalis. In addition to diuretics and digitalis, treatment often includes the use of preload-and afterloadreducing agents. Optimal use of these drugs and correction of CHF may be aided by consultation with a cardiologist. It is preferable to continue the usual regimen of cardioactive drugs throughout the perioperative period.


Gynecology_Novak

Gynecology_Novak. Postoperative CHF frequently results from excessive administration of intravenous ﬂuids and blood products. Other common postoperative causes are myocardial infarction, systemic infection, pulmonary embolism, and cardiac arrhythmias. The cause of postoperative heart failure must be diagnosed because, to be successful, treatment should be directed simultaneously to the underlying cause. Postoperative diagnosis of CHF is more difficult than preoperative diagnosis because the signs and symptoms of CHF are not specific and may result from other causes. The most reliable method of detecting CHF is chest radiography, in which the presence of cardiomegaly or evidence of pulmonary edema is a helpful diagnostic feature.


Gynecology_Novak

Gynecology_Novak. Acute postoperative CHF frequently manifests as pulmonary edema. Treatment of pulmonary edema may include the use of intravenous furosemide, supplemental oxygen, morphine sulfate, and elevation of the head of the bed. Intravenous aminophylline may be useful if cardiogenic asthma is present. Electrocardiography, in addition to laboratory evaluation, including arterial blood gas, serum electrolyte, and renal function chemistry measurements, should be obtained expediently. If the patient’s condition does not improve rapidly, she should be transferred to an intensive care unit. Arrhythmias Nearly all arrhythmias found in otherwise healthy patients are asymptomatic and of limited consequence. In patients with underlying cardiac disease, however, even brief episodes of arrhythmias may result in significant cardiac morbidity and mortality.


Gynecology_Novak

Gynecology_Novak. Preoperative evaluation of arrhythmias by a cardiologist and anesthesiologist is important because many anesthetic agents and surgical stress contribute to the development or worsening of arrhythmias. In patients undergoing continuous electrocardiographic monitoring during surgery, a 60% incidence of arrhythmias, excluding sinus tachycardia, are reported (201). Patients with heart disease have an increased risk of arrhythmias, most commonly ventricular arrhythmias (201). Patients without cardiac disease are more likely to develop supraventricular arrhythmias during surgery. Patients taking antiarrhythmic medications before surgery should continue taking those drugs during the perioperative period. Initiation of antiarrhythmic medications is rarely indicated preoperatively, but consultation with a cardiologist is recommended for patients in whom arrhythmias are detected before surgery.


Gynecology_Novak

Gynecology_Novak. Patients with first-degree atrioventricular (AV) block or asymptomatic Mobitz I (Wenckebach) second-degree AV block require no preoperative therapy. A pacemaker is appropriate in patients with symptomatic Mobitz II second-or third-degree AV block before elective surgery (202). In emergency situations, a pacing pulmonary artery catheter can be used. Before performing surgery on patients with a permanent pacemaker, the type and location of the pacemaker should be determined because electrocautery units may interfere with demand-type pacemakers (203).


Gynecology_Novak

Gynecology_Novak. When performing gynecologic surgery on patients with pacemakers, it is preferable to place the electrocautery unit ground plate on the leg to minimize interference by preventing the pacemaker generator from sitting within the electrocautery circuit and to maximize distance from the pacemaker device. If possible, use of bipolar cautery devices are recommended rather than monopolar devices. In patients with a demand pacemaker in place, the pacemaker should be converted preoperatively to the fixed-rate (or asynchronous) mode. Although this can be accomplished oftentimes by placing a magnet over the pacemaker, it may be better to reprogram the pacemaker preoperatively and then again postoperatively. Patients should be monitored continuously intraoperatively with both telemetry and continuous pulse oximeter. Close coordination with anesthesia and cardiology is imperative. Patients with an implantable cardioverter defibrillator device should have their device programmed off prior to surgery


Gynecology_Novak

Gynecology_Novak. oximeter. Close coordination with anesthesia and cardiology is imperative. Patients with an implantable cardioverter defibrillator device should have their device programmed off prior to surgery and reprogrammed postoperatively (155).


Gynecology_Novak

Gynecology_Novak. Surgery is not contraindicated in patients with bundle branch blocks or hemiblocks (204). Peri-operative mortality rates are not increased by bundle-branch block. Complete heart block rarely develops during noncardiac surgical procedures in patients with conduction system disease. The presence of a left bundle-branch block may indicate the presence of aortic stenosis, which can increase surgical mortality if it is severe. Valvular Heart Disease Although there are many forms of valvular heart disease, two types—aortic and mitral stenosis—primarily are associated with significantly increased operative risk (205). Patients with significant aortic stenosis appear to be at greatest risk, which is increased in the presence of atrial fibrillation, congestive heart failure, or coronary artery disease. Significant stenosis of aortic or mitral valves should be repaired before elective gynecologic surgery (176).


Gynecology_Novak

Gynecology_Novak. Severe valvular heart disease usually is evident during physical exertion. Common findings in such patients are listed in Table 22.18. The classic history presented by patients with severe aortic stenosis includes exercise dyspnea, angina, and syncope, whereas symptoms of mitral stenosis are paroxysmal and effort dyspnea, hemoptysis, and orthopnea. Most patients have a remote history of rheumatic fever. Severe stenosis of either valve is considered to be a valvular area of less than 1 cm2, and diagnosis can be confirmed by echocardiography or cardiac catheterization.


Gynecology_Novak

Gynecology_Novak. Patients with valvular abnormalities are subdivided by the American Heart Association into risk groups for the development of subacute bacterial endocarditis following surgery. Patients in the highest risk groups should receive prophylactic antibiotics immediately preoperatively to prevent subacute bacterial endocarditis (Table 22.8). As defined by the American Heart Association, only patients with prosthetic cardiac valves, congenital heart disease, and cardiac transplantation who develop cardiac valvulopathy should receive perioperative endocarditis prophylaxis (76). All other patients do not require antibiotics for subacute bacterial endocarditis prophylaxis. Routine prophylaxis for GI or GU procedures is not recommended. Only in cases of a known infection of the GI or GU tract should antibiotics coverage for enterococcus with amoxicillin or ampicillin or vancomycin be provided.


Gynecology_Novak

Gynecology_Novak. Patients with aortic and mitral stenosis tolerate sinus tachycardia and other tachyarrhythmias poorly. In patients with aortic stenosis, sufficient levels of digitalis should be provided to correct preoperative tachyarrhythmias, and propranolol may be used to control sinus tachycardia. Patients with mitral valve stenosis often have atrial fibrillation and, if present, digitalis should be used to reduce rapid ventricular response. Patients with mechanical heart valves usually tolerate surgery well (206). These patients should receive antibiotic prophylaxis (Table 22.8). If the patient is taking aspirin therapy, it should be discontinued 1 week before the procedure and restarted as soon as it is considered safe by the Table 22.18 Signs and Symptoms of Valvular Heart Disease 1. Systolic murmur at right sternal border, which radiates into carotids 2. 3. 4. Chest radiograph with calcified aortic ring, left ventricular enlargement 5.


Gynecology_Novak

Gynecology_Novak. Systolic murmur at right sternal border, which radiates into carotids 2. 3. 4. Chest radiograph with calcified aortic ring, left ventricular enlargement 5. Electrocardiogram with high R waves, depressed T waves in lead I, and precordial leads Mitral stenosis 1. 2. 3. 4. 5. Chest radiograph with left atrial dilation 6.


Gynecology_Novak

Gynecology_Novak. 2. 3. 4. 5. Chest radiograph with left atrial dilation 6. Electrocardiogram with large P waves and right axis deviation surgeon. Patients with a bileaﬂet aortic valve with no risk factors (atrial fibrillation, previous thromboembolism, left ventricular dysfunction, a hypercoagulable state, older generation thrombogenic valve) generally do not require anticoagulation bridging. Warfarin should be stopped 72 hours prior to the procedure and resumed 24 hours after the procedure. In contrast, patients with a mechanical aortic valve and any above mentioned risk factor, or a mechanical mitral valve, should be bridged with intravenous unfractionated heparin when the INR falls below 2. The heparin drip should be stopped approximately 6 to 8 hours before the procedure and restarted as soon as possible after surgery when the patient is deemed stable from postoperative bleeding risk. The heparin bridge can be stopped when the INR reaches therapeutic levels (207).


Gynecology_Novak

Gynecology_Novak. In the postoperative period, patients with mitral stenosis should be carefully monitored for pulmonary edema because they may not be able to compensate for the amount of intravenous ﬂuid administered during surgery. Prevention of tachycardia is important, as it may lead to pulmonary edema. Patients with mitral stenosis frequently have pulmonary hypertension and decreased airway compliance. They may require more pulmonary support and therapy postoperatively, including prolonged mechanical ventilation.


Gynecology_Novak

Gynecology_Novak. For patients with significant aortic stenosis, it is imperative that a sinus rhythm be maintained during the postoperative period. Even sinus tachycardia can be deleterious because it shortens the diastolic time. Bradycardia less than 45 beats per minute should be treated with atropine. Supraventricular dysrhythmias may be controlled with verapamil or direct-current cardioversion. Particular attention should be provided to the maintenance of proper ﬂuid status, digoxin levels, electrolyte levels, and blood replacement.


Gynecology_Novak

Gynecology_Novak. Hypertension Patients with controlled essential hypertension have no increased risk of perioperative cardiac morbidity or mortality (208). Patients with concomitant heart disease are at elevated risk and should be completely evaluated by a cardiologist preoperatively. Laboratory studies should include an ECG, chest radiography, blood count, urinalysis, and serum electrolytes and creatinine measurement. Antihypertensive medications should be continued perioperatively. Beta-blockers should be continued, parenterally if necessary, to avoid rebound tachycardia, hypercontractility, and hypertension. Clonidine may cause significant rebound hypertension if withdrawn acutely. Angiotensin converting enzyme inhibitor agents and angiotensin II receptor antagonists are associated with increased intraoperative hypotension and perioperative renal dysfunction possibly resulting from a hypovolumic state. It may be prudent to withhold these agents on the morning of surgery and resume them


Gynecology_Novak

Gynecology_Novak. intraoperative hypotension and perioperative renal dysfunction possibly resulting from a hypovolumic state. It may be prudent to withhold these agents on the morning of surgery and resume them postoperatively when good renal function and euvolumia is confirmed (155).


Gynecology_Novak

Gynecology_Novak. Patients with diastolic pressures higher than 110 mm Hg or systolic pressures higher than 180 mm Hg should receive medication to control their hypertension before surgery. Beta-blockers may be particularly effective agents for treatment of preoperative hypertension (179). Chronically hypertensive patients are very susceptible to intraoperative hypotension because of impaired autoregulation of blood ﬂow to the brain and require a higher mean arterial pressure to maintain adequate perfusion (209). During induction of anesthesia, episodes of hypertension occur, and such episodes are seen more frequently in patients with baseline hypertension. Postoperative hypertension is usually treated parenterally because gastrointestinal absorption may be diminished, and transdermal absorption can be erratic in patients who are cold and rewarming. Commonly used parenteral antihypertensives are listed in Table 22.19.


Gynecology_Novak

Gynecology_Novak. Increasing numbers of patients undergo coronary revascularization procedures, otherwise known as coronary artery bypass grafting, or percutaneous coronary intervention, typically stent placement. With the evolution of bare metal and drug-eluting stents, perioperative management of cardiovascular thrombotic risk versus perioperative bleeding and mortality is challenged. Given that drug-eluting stents generally require 12 months’ treatment with dual agent aspirin and thienopyridine (i.e., clopidogrel), the American College of Cardiology and American Heart Association (ACC/AHA) guidelines recommend avoiding elective surgery within 12 months of drug-eluting stent placement. When surgery cannot wait, the ACC/AHA recommends continuation of aspirin perioperatively, discontinuation of thienopyridine 5 days prior to surgery, and resuming it as soon as possible postoperatively. Ultimately the risk of perioperative morbidity secondary to bleeding must be weighed against the risk of repeat


Gynecology_Novak

Gynecology_Novak. 5 days prior to surgery, and resuming it as soon as possible postoperatively. Ultimately the risk of perioperative morbidity secondary to bleeding must be weighed against the risk of repeat thrombosis and cardiovascular morbidity and mortality. If a patient requires new placement of a cardiac stent and requires a


Gynecology_Novak

Gynecology_Novak. Table 22.19 Common Parenteral Antihypertensives Hemodynamic Monitoring Hemodynamic monitoring is integral to the perioperative management of patients with cardiovascular and pulmonary diseases. The major impetus for this advancement resides in the need for the quantitative estimate of cardiac function, resulting in the development of bedside pulmonary artery catheterization. The impact of monitoring cardiac function is demonstrated by the significant reduction of myocardial infarctions in high-risk patients who are aggressively monitored for 72 to 96 hours postoperatively (175).


Gynecology_Novak

Gynecology_Novak. Before the development of the pulmonary artery catheter, central venous pressure (CVP) measurement was used to assess intravascular volume status and cardiac function. To measure the CVP, a catheter is placed in the central venous system, most frequently the superior vena cava. A water manometer or a calibrated pressure transducer is connected to the CVP line, allowing an estimation of right atrial pressure. Right atrial pressure is determined by the balance between cardiac output and venous return. Cardiac output is determined by heart rate, myocardial contractility, preload, and afterload. If the pulmonary vascularity and left ventricular function are normal, the CVP accurately reﬂects the left ventricular end-diastolic pressure (LVEDP). The LVEDP reﬂects cardiac output or systemic perfusion and was considered the standard estimator of left ventricular pump function. Venous return is determined primarily by the mean systemic pressure, which propels blood toward the heart, balanced


Gynecology_Novak

Gynecology_Novak. and was considered the standard estimator of left ventricular pump function. Venous return is determined primarily by the mean systemic pressure, which propels blood toward the heart, balanced against resistance to venous return, which acts in the opposite direction. If right ventricular function is normal, the CVP accurately reﬂects intravascular volume.


Gynecology_Novak

Gynecology_Novak. Left and right ventricular function is frequently abnormal or discordant; therefore, the relationship of CVP to cardiac function and to intravascular volume is not maintained. When this occurs, measurement of pulmonary artery occlusion pressure can be used to accurately assess volume status and cardiovascular function. The use of a pulmonary artery catheter allows detection of changes in cardiovascular function with more sensitivity and rapidity than clinical observation.


Gynecology_Novak

Gynecology_Novak. The balloon-tipped pulmonary artery catheter (Swan-Ganz catheter) can measure pulmonary artery and pulmonary artery occlusion pressures (210). The catheter can measure cardiac output, be used to perform intracavitary electrocardiography, and provide temporary cardiac pacing. The standard pulmonary artery occlusion catheter is a 7-French, radiopaque, ﬂexible, polyvinyl chloride, 4-lumen catheter with a 1.5-mL latex balloon at its distal tip. Most often, a right internal jugular cannulation is used for placement of the catheter, because this site provides the most direct access into the right atrium and has fewer complications when compared with a subclavian route of placement. After the catheter is placed into the right atrium, the balloon is inﬂated, and the catheter is pulled by blood ﬂow through the right ventricle into the pulmonary artery. The position of the catheter can be identified and followed by the various pressure waveforms generated by the right atrium, right ventricle,


Gynecology_Novak

Gynecology_Novak. through the right ventricle into the pulmonary artery. The position of the catheter can be identified and followed by the various pressure waveforms generated by the right atrium, right ventricle, and pulmonary artery. As the catheter passes through increasingly smaller branches of the pulmonary artery, the inﬂated balloon eventually occludes the pulmonary artery.


Gynecology_Novak

Gynecology_Novak. The distal lumen of the catheter, which is beyond the balloon, measures left atrial pressure (LAP) and, in the absence of mitral valvular disease, LAP approximates LVEDP. Pulmonary–capillary wedge pressure (PCWP) equals the LAP, which equals LVEDP and is normal at 8 to 12 mm Hg. Because the standard pulmonary artery catheter has an incorporated thermistor, thermodilution studies can be performed to determine cardiac output. This thermodilution method is performed by injecting cold 5% dextrose in water through the proximal port of the catheter, which cools the blood entering the right atrium. The change in temperature measured at the more distal thermistor (4 cm from the catheter tip) generates a curve proportional to cardiac output. Knowledge of the cardiac output is helpful in establishing cardiovascular diagnoses. For example, a patient with hypotension, low-to-normal wedge pressure, and a cardiac output of 3 L per minute is most likely hypovolemic. The same patient with a cardiac


Gynecology_Novak

Gynecology_Novak. cardiovascular diagnoses. For example, a patient with hypotension, low-to-normal wedge pressure, and a cardiac output of 3 L per minute is most likely hypovolemic. The same patient with a cardiac output of 8 L per minute is probably septic with resultant low systemic vascular resistance.


Gynecology_Novak

Gynecology_Novak. Pulmonary artery catheters are associated with a small but significant complication rate. The complications can be grouped into those occurring during venous cannulation or insertion, during maintenance and use, and those related to interpretation of hemodynamic data (210). The most common problems encountered during venous access are cannulation of the carotid or subclavian artery and introduction of a pneumothorax. Problems resulting from the catheter itself include dysrhythmias, sepsis, and disruption of the pulmonary artery. Pulmonary artery catheters (PAC) should be placed under the supervision of experienced personnel in a setting in which complications can be rapidly diagnosed and treated. Accessory equipment such as resuscitation equipment and an external pacing device must be immediately available. Ultrasound and ﬂuoroscopic equipment if available may aid in PAC placement (211).


Gynecology_Novak

Gynecology_Novak. The effect of PAC use on patient outcome is controversial. Several large trials did not confer a definite benefit to PAC use. One multi-institutional study examined the association of PAC placement within the first 24 hours of hospital stay and its associated outcomes. They found a higher mortality rate in patients who received a PAC than those who did not have a PAC (212). The study was limited because it was retrospective and not randomized. A randomized controlled trial of 1,994 high-risk (American Society of Anesthesiologists class III or IV risk) patients age 60 or older undergoing urgent or elective major noncardiac surgery compared outcomes of those who underwent PAC placement versus standard care. Results analyzed by a blinded assessor revealed no benefit of PAC over standard care with central venous catheters (213). Another randomized controlled trial enrolling 65 intensive care units in the United Kingdom found no difference in mortality among critically ill patients managed


Gynecology_Novak

Gynecology_Novak. with central venous catheters (213). Another randomized controlled trial enrolling 65 intensive care units in the United Kingdom found no difference in mortality among critically ill patients managed with or without a PAC (214). A meta-analysis of 13 randomized controlled trials of PAC use found no significant difference in mortality rates and an increased use of ionotropes and intravenous vasodilators (215). Routine preoperative use of PAC in noncardiac surgery patients is no longer indicated. Use of PAC in critically ill patients postoperatively remains controversial.


Gynecology_Novak

Gynecology_Novak. Hematologic Disorders The presence of hematologic disorders, although uncommon in gynecologic patients, significantly affects operative morbidity and mortality and should be considered routinely in preoperative evaluation. Preoperative assessment should include consideration of anemia, platelet and coagulation disorders, white blood cell function, and immunity.


Gynecology_Novak

Gynecology_Novak. Anemia Moderate anemia is not in itself a contraindication to surgery because it can be corrected by transfusion. If possible, surgery should be postponed until the cause of the anemia can be identified and the anemia corrected without resorting to transfusion. By tradition, anesthetic and surgical practice recommended a hemoglobin level of greater than 10 g/dL or a hematocrit of greater than 30%. Data suggest a lower tolerance for pre-and intraoperative transfusion threshold to improve intra-and postoperative morbidity and mortality (216–219). It remains that no universal “transfusion threshold” is agreed upon, but that a hematocrit of less than 24% should prompt strong consideration (219). The circulating blood volume provides oxygen-carrying capacity and tissue oxygenation. Usually this capacity is reﬂected by the hemoglobin level and hematocrit. Under certain circumstances this is not the case. After an acute blood loss or before plasma expansion by extracellular ﬂuid occurs,


Gynecology_Novak

Gynecology_Novak. this capacity is reﬂected by the hemoglobin level and hematocrit. Under certain circumstances this is not the case. After an acute blood loss or before plasma expansion by extracellular ﬂuid occurs, hematocrit measurements may be normal despite a low circulating blood volume. Conversely, overhydration may result in low hematocrit and hemoglobin levels despite adequate red blood cell mass.


Gynecology_Novak

Gynecology_Novak. Individual tolerance of anemia depends on overall physical fitness and cardiovascular reserve. The effects of anemia depend on its magnitude, the rate at which it occurs, the oxygen requirement of the patient, and the ability of physiologic mechanisms to compensate (220). Maintenance of adequate tissue perfusion requires an increase in cardiac output as hemoglobin concentration falls (193). In the healthy patient, oxygen delivery is unchanged when it falls below 7 g/dL (221). In contrast, a patient with ischemic heart disease will not tolerate anemia as well (222). The presence of cardiac, pulmonary, or other serious illness justifies a more conservative approach to the management of anemia. Patients with longstanding anemia may have normal blood volume levels and tolerate surgical procedures well. There is no evidence that mild to moderate anemia increases perioperative morbidity or mortality (222).


Gynecology_Novak

Gynecology_Novak. Autologous blood transfusion may be an acceptable option for patients. Patients with normal hematocrit levels may store autologous blood preoperatively to reduce the need for allogenic blood transfusion and minimize the risk of infections and immunologic problems (193). Recombinant human erythropoietin may increase collection and reduce preoperative anemia in these patients (223,224). Intraoperative blood collection and homologous transfusion can be employed to limit the need for allogenic blood transfusion.


Gynecology_Novak

Gynecology_Novak. Autologous blood donation is advocated as a safer alternative for the patient; however, the use of preoperative autologous blood donation has come under scrutiny (225,226). Preoperative autologous blood may lead to more liberal blood transfusion, iatrogenic anemia, volume overload, and bacterial contamination (227). Preoperative autologous blood donation is poorly cost-effective (228). The National Heart, Lung, and Blood Institute does not recommend collection of autologous blood for procedures with a likelihood of transfusion less than 10%, such as uncomplicated abdominal and vaginal hysterectomies (229). Surgical hemostasis is provided by platelet adhesion to injured vessels, which plugs the opening as the coagulation cascade is activated, resulting in the formation of fibrin clots. Functional platelets and coagulation pathways are necessary to prevent excessive surgical bleeding. Platelet dysfunction is encountered preoperatively more frequently than coagulation disorders.


Gynecology_Novak

Gynecology_Novak. Platelets may be deficient in both number and function. The normal peripheral blood count is 150,000 to 400,000 per mm3, and the normal lifespan of a platelet is approximately 10 days. Although there is no clear-cut correlation between the degree of thrombocytopenia and the presence or amount of bleeding, several generalizations can be made. If the platelet count is higher than 100,000/mm3 and the platelets are functioning normally, there is little chance of excessive bleeding during surgical procedures. Patients with a platelet count higher than 75,000/mm3 almost always have normal bleeding times, and a platelet count higher than 50,000/mm3 is probably adequate. A platelet count lower than 20,000/mm3 often will be associated with severe and spontaneous bleeding. Platelet counts higher than 1,000,000/mm3 are often, paradoxically, associated with bleeding.


Gynecology_Novak

Gynecology_Novak. If the patient’s platelet count is lower than 100,000/mm3 , an assessment of bleeding time should be obtained. If the bleeding time is abnormal and surgery must be performed, an attempt should be made to raise the platelet count by administering platelet transfusions immediately before surgery. In patients with immune destruction of platelets, human leukocyte antigen (HLA)–matched donor-specific platelets may be required to prevent rapid destruction of transfused platelets. If surgery can be postponed, a hematology consultation should be obtained to identify and treat the cause of the platelet abnormality.


Gynecology_Novak

Gynecology_Novak. Abnormally low platelet counts result from either decreased production or increased consumption of platelets. Although there are numerous causes of thrombocytopenia, most are exceedingly uncommon. Decreased platelet production may be drug induced and is associated with the use of sulfonamides, cinchona alkaloids, thiazide diuretics, NSAIDs, gold salts, penicillamine, anticonvulsants, and heparins (230). Decreased platelet count is a feature of several diseases, including vitamin B12 and folate deficiency, aplastic anemia, myeloproliferative disorders, renal failure, and viral infections. Inherited congenital thrombocytopenia is extremely rare. More commonly, thrombocytopenia results from immune destruction of platelets by diseases such as idiopathic thrombocytopenia purpura and collagen vascular disorders. Consumptive thrombocytopenia is a feature of disseminated intravascular coagulation, which is encountered most frequently in conjunction with sepsis or malignancy in the


Gynecology_Novak

Gynecology_Novak. collagen vascular disorders. Consumptive thrombocytopenia is a feature of disseminated intravascular coagulation, which is encountered most frequently in conjunction with sepsis or malignancy in the preoperative population.


Gynecology_Novak

Gynecology_Novak. Platelet dysfunction most often is acquired, but may be inherited. Occasionally, a patient with von Willebrand disease, the second most common inherited disorder of coagulation, may be encountered in the preoperative setting. More commonly, platelet dysfunction results from the use of drugs (e.g., aspirin and amitriptyline), and in patients with resulting prolonged bleeding time, the drug should be withheld for 7 to 10 days before surgery. Uremia and hepatic diseases can affect platelet function.


Gynecology_Novak

Gynecology_Novak. Platelet dysfunction is more difficult to diagnose than abnormalities of platelet count. A history of easy bruising, petechiae, bleeding from mucous membranes, or prolonged bleeding from minor wounds may signify an underlying abnormality of platelet function. Such dysfunction can be identified with the help of a bleeding time, but full characterization of the underlying etiology should be carried out with hematologic consultation. If at all possible, surgery should be postponed until therapy is instituted.


Gynecology_Novak

Gynecology_Novak. Disorders of the coagulation cascade often are diagnosed through a personal or family history of excessive bleeding during minor surgery, childbirth, or menses. Many women with menorrhagia are referred for surgical intervention and require a thorough preoperative evaluation for possible inherited disorders of hemostasis, such as factor VIII (hemophilia), factor IX (Christmas disease), factor XI deficiencies, and von Willebrand disease. Von Willebrand disease is the most common hereditary bleeding disorder, with prevalence in the general population of roughly 1% (231). Seventy percent to 90% of patients with von Willebrand disease have menorrhagia (231). Identified women can be treated effectively with desmopressin nasal spray, avoiding unanticipated or excessive bleeding during surgery (232). In the absence of a genetic diagnosis, the diagnosis of von Willebrand disease is difficult and involves a combination of clinical and laboratory assessments, including von Willebrand factor


Gynecology_Novak

Gynecology_Novak. (232). In the absence of a genetic diagnosis, the diagnosis of von Willebrand disease is difficult and involves a combination of clinical and laboratory assessments, including von Willebrand factor antigen and von Willebrand factor functional activity or ristocetin cofactor assay (232). Physiologic ﬂuctuations occur with von Willebrand factor levels, requiring repeat testing and consultation or referral to a hematologist. It is recommended that women presenting with menorrhagia without obvious pelvic abnormalities should be routinely screened for inherited bleeding disorders before undergoing invasive procedures.


Gynecology_Novak

Gynecology_Novak. There are few commonly prescribed drugs that affect coagulation factors, the exceptions being warfarin and heparin. Disease states that may be associated with decreased coagulation factor levels are primarily liver disease, vitamin K deficiency (secondary to obstructive biliary disease, intestinal malabsorption, or antibiotic reduction of bowel ﬂora), and disseminated intravascular coagulation. Preoperative laboratory screening for coagulation deficiencies is controversial. Routine screening is not warranted in patients who do not have historical evidence of a bleeding problem (233). Patients who are seriously ill or who will be undergoing extensive surgical procedures should undergo testing preoperatively to determine prothrombin time, partial thromboplastin time, fibrinogen level, and platelet count.


Gynecology_Novak

Gynecology_Novak. Abnormally high or low white blood cell counts are not an absolute contraindication to surgery; they should be considered relative to the need for surgery. Evaluation of an elevated or decreased white blood cell count should be undertaken before elective surgery. Patients with absolute granulocyte counts lower than 1,000/mm3 are at increased risk of severe infection and perioperative morbidity and mortality and should undergo surgery only for life-threatening indications (234).


Gynecology_Novak

Gynecology_Novak. Packed red blood cells, which may be stored for several weeks, are used for most postoperative transfusions. Most clotting factors are stable for long periods. The exceptions are factors V and VIII, which decrease to 15% and 50% of normal, respectively. Most hematologic problems observed in the postoperative period are related to perioperative bleeding and blood component replacement. Although the primary cause of the bleeding is usually lack of surgical hemostasis, other factors, including deranged coagulation, may compound the problem. Such coagulopathy can result from massive transfusion (less than one blood volume) and is thought to be caused by dilution of platelets and labile coagulation factors by platelet-and factor-poor packed red blood cells (PRBCs), fibrinolysis, and disseminated intravascular coagulation.


Gynecology_Novak

Gynecology_Novak. Areviewin Transfusion questioned the traditional practice of limiting blood component replacement in massive transfusion. Summarizing 14 articles and encompassing nearly 4,600 patients, the conclusions note a decrease in all-cause mortality with more liberal transfusion of platelets and fresh frozen plasma (FFP) (235). A task force for the American Society of Anesthesiologists recommended critical values for replacement in patients with massive transfusion and microvascular bleeding (193): 1. Platelet transfusion usually is indicated for counts less than 50,000/mm3 (with intermediate platelet counts, i.e., 50,000/mm3 to 100,000/mm3, the transfusion of platelet concentrates should be based on the risk of more significant bleeding). 2. Fresh frozen plasma therapy is indicated if the prothrombin or activated partial thromboplastin time values exceed 1.5 times the normal value. 3.


Gynecology_Novak

Gynecology_Novak. 2. Fresh frozen plasma therapy is indicated if the prothrombin or activated partial thromboplastin time values exceed 1.5 times the normal value. 3. Cryoprecipitate transfusion is indicated if fibrinogen concentrations decrease to less than 80 to 100 mg/dL. Cryoprecipitate transfusions are recommended for prophylaxis in nonbleeding perioperative patients with fibrinogen deficiencies or von Willebrand disease refractory to desmopressin acetate and bleeding patients with von Willebrand disease (232).


Gynecology_Novak

Gynecology_Novak. Donor blood is stored in the presence of citrate, which chelates calcium to prevent clotting, increasing the theoretical risk of hypocalcemia following massive transfusion. Citrate is metabolized at a rate equivalent to 20 U of blood transfused per hour; thus, routine supplementation of calcium is unnecessary. Close monitoring of calcium levels is required in patients with hypothermia, liver disease, or hyperventilation because citrate metabolism may be slowed. Hepatic metabolism of citrate to bicarbonate can result in metabolic alkalosis following transfusion, resulting in subsequent hypokalemia, despite the high level of extracellular potassium in stored blood.


Gynecology_Novak

Gynecology_Novak. Pulmonary Disease In patients undergoing abdominal surgery, several pulmonary physiologic changes manifest secondary to immobilization, anesthetic irritation of the airways, and the splinting of breathing that inevitably occurs secondary to incisional pain. Pulmonary physiologic changes include a decrease in the functional residual capacity (FRC), an increase in ventilation perfusion mismatching, and impaired mucociliary clearance of secretions from the tracheobronchial tree (236). Risk factors for postoperative pulmonary complications include the following (237,238) (Table 22.20): Upper abdominal or thoracic, or abdominal aortic aneurysm surgery Smoking within 2 months of surgery Use of pancuronium for general anesthesia Table 22.20 Predictors of Postoperative Pulmonary Complicationsa


Gynecology_Novak

Gynecology_Novak. Smoking within 2 months of surgery Use of pancuronium for general anesthesia Table 22.20 Predictors of Postoperative Pulmonary Complicationsa FEV, forced expiration volume; FVC, forced vital capacity; PaO2, partial pressure of oxygen, arterial; PaCO2, partial pressure of carbon dioxide, arterial. aComplication defined as atelectasis or pneumonia. Adapted from Blosser SA, Rock P. Asthma and chronic obstructive lung disease. In: Breslow MJ, Miller CJ, Rogers MC, eds. Perioperative management. St. Louis, MO: Mosby, 1990:259–280. Poor nutrition (serum albumin <3.5mg/dL or BUN <8).


Gynecology_Novak

Gynecology_Novak. Probable risk factors include general anesthesia, preoperative partial pressure of carbon dioxide, arterial (PaCO2) greater than 45 mm Hg, and emergency surgery. Risk factors that could increase the postoperative risk are upper respiratory infection, abnormal chest x-ray, and age. Preoperative pulmonary function testing is of unproven value in patients not undergoing thoracic surgery (237). This is based on multiple reasons: first, a lower limit of forced expiration volume (FEV1) did not correlate with pulmonary complications; second, pulmonary complications can occur in the context of a normal FEV1; and third, if an FEV1 were able to predict a pulmonary complication putting the patient at increased risk, it would not change the need for aggressive postoperative prophylactic measures (237). The routine performance of preoperative arterial blood gas measurements does not improve assessment of risk (236). Noninvasive pulse-oximetry measurements can detect patients with hypoxemia (236).


Gynecology_Novak

Gynecology_Novak. The routine performance of preoperative arterial blood gas measurements does not improve assessment of risk (236). Noninvasive pulse-oximetry measurements can detect patients with hypoxemia (236). The presence of hypercarbia on arterial blood gas measurements does not predict postoperative pulmonary complications (236).


Gynecology_Novak

Gynecology_Novak. Young, healthy patients rarely have abnormal chest x-rays. Chest x-rays should not be performed routinely in these patients. Most patients with abnormal chest x-rays have history or physical examination findings suggestive of pulmonary disease. Chest x-rays should be limited to patients older than 50 years of age, with a history of smoking or of pulmonary disease, who have evidence of cardiopulmonary disease and in whom a metastatic malignancy is suspected. Although they have limited usefulness in predicting postoperative pulmonary complications, chest x-rays provide a valuable baseline in elderly patients, patients with chronic pulmonary diseases, and those with known lung metastases (236–238).


Gynecology_Novak

Gynecology_Novak. Asthma Asthma affects approximately 22 million individuals in the United States, including 6% of children (239). It is characterized by a history of episodic wheezing, physiologic evidence of reversible obstruction of the airways either spontaneously or following bronchodilator therapy, and pathologic evidence of chronic inﬂammatory changes in the bronchial submucosa. Asthma is not a disease of airway physiology in which hypertrophy and increased contractility of bronchial smooth muscle is the dominant lesion; rather, it is an inﬂammatory disease affecting the airways that secondarily results in epithelial damage, leukocytic infiltration, and increased sensitivity of the airways to a number of stimuli. The treatment of asthma is directed toward relaxing the airways and alleviating inﬂammation (239).


Gynecology_Novak

Gynecology_Novak. Multiple stimuli are noted to precipitate or exacerbate asthma, including environmental allergens or pollutants, respiratory tract infections, exercise, cold air, emotional stress, nonselective beta-adrenergic blockers, and NSAIDs (239). Management of asthma includes removal of the inciting stimuli as well as use of appropriate pharmacologic therapy. The optimal therapy for asthma involves managing the acute symptoms and long-term management of the inﬂammatory component of the disease. Pharmacotherapy of Asthma The treatment of asthma is divided into long-term control modalities and short-term modalities.


Gynecology_Novak

Gynecology_Novak. Recognizing the underlying pathophysiology in asthma as an inﬂammatory condition, inhaled corticosteroids are the cornerstone for maintenance therapy. Onset of action is slow (several hours), and up to 3 months of steroid therapy may be required for optimal improvement of bronchial hyperresponsiveness. Even with acute bronchospasm, steroid treatment can enhance the beneficial effect of beta-adrenergic treatment. During acute exacerbations of asthma, a short course of oral steroids, in addition to inhaled steroids, may be necessary. For adults with chronic asthma, only a minority will require chronic oral steroid therapy. Patients taking oral steroids should receive intravenous steroid support in the form of 100 mg of hydrocortisone IV every 8 hours perioperatively, sharply tapering within 24 hours of surgery to avoid adrenal insufficiency. Other long-term control therapies include (239): 1.


Gynecology_Novak

Gynecology_Novak. Leukotriene modifiers (i.e., montelukast): These agents interfere with leukotrienes, substances released from mast cells, eosinophils, and basophils important in the inﬂammatory response. 2. Cromolyn sodium: Highly active in the treatment of seasonal allergic asthma in children and young adults. It is usually not as effective in older patients or in patients in whom asthma is not allergic in nature. 3. Immunomodulators: Omalizumab, a monoclonal antibody to immunoglobulin E (IgE), has gained support for prevention and may be an important adjunct in symptomatic suppression. 4. Long term beta2-adrenergic agonists (i.e., salmeterol): Although not appropriate for single agent management or use in mild disease, they are an important adjunct in the suppression of symptoms in patients with significant disease. 5.


Gynecology_Novak

Gynecology_Novak. 5. Methylxanthines (i.e., theophylline): These were relegated to third-line status in the management of asthma. Theophylline toxicity can develop when other drugs such as ciproﬂoxacin, erythromycin, allopurinol, Inderal, or cimetidine are concomitantly administered. Therapeutic serum levels must be monitored closely. β2-adrenergic agonists remain the first-line drugs for acute asthma attacks. These drugs, inhaled four to six times daily, rapidly relax smooth muscle in the airways and are effective for up to 6 hours. Studies of beta2 agonists in chronic asthma failed to show any inﬂuence of these agents on the inﬂammatory component of asthma. β2 agonists are recommended for short-term relief of bronchospasm (“rescue inhalers”) or as first-line treatment for patients with very infrequent symptoms or symptoms provoked solely by exercise (239).


Gynecology_Novak

Gynecology_Novak. Anticholinergic agents are weak bronchodilators that work via inhibition of muscarinic receptors in the smooth muscle of the airways. The quaternary derivatives such as ipratropium bromide (Atrovent) are available in an inhaled form that is not absorbed systemically. Anticholinergic drugs may provide additional benefit in conjunction with standard steroid and bronchodilator therapy but should not be used as single-agent therapy because they do not inhibit mast cell degranulation, do not have any effect on the late response to allergens, and do not have an anti-inﬂammatory effect (239). Perioperative Management of Asthma In patients with asthma, elective surgery should be postponed whenever possible until pulmonary function and pharmacotherapeutic management are optimized. The most recent guidelines of the American Academy of Allergy, Asthma and Immunology’s recommend three interventions to reduce perioperative pulmonary complications related to asthma (239): 1.


Gynecology_Novak

Gynecology_Novak. Review the patient’s asthmatic control, including the need for oral steroids. 2. Optimize the patient’s symptomatic control through the use of long-acting pharmacotherapy, including oral steroids if needed. 3. For patients on oral steroid therapy within 6 months of therapy or for patients using large doses of inhaled corticosteroids, consider perioperative stress dose steroids.


Gynecology_Novak

Gynecology_Novak. For mild asthma, the use of inhaled beta-adrenergic agonists preoperatively may be all that is required. For chronic asthma, optimization of steroid therapy will greatly decrease alveolar inﬂammation and bronchiolar hyperresponsiveness. Inhaled beta2-agonists should be added to therapy as needed for further control of asthma. Each drug prescribed should be used in maximal dosage before adding an additional agent. Preoperative treatment with combined corticosteroids and an inhaled beta2-adrenergic agonist for a 5-day period may decrease the risk of postoperative bronchospasm in patients with asthma (240). For patients undergoing emergent surgery who have significant bronchoconstriction, a multimodal approach should be instituted, including aggressive bronchodilator inhalation therapy and intravenous steroid therapy. The role of spirometry, outside of cardiothoracic procedures, has limited value in predicting postoperative pulmonary complications and should be limited to the


Gynecology_Novak

Gynecology_Novak. and intravenous steroid therapy. The role of spirometry, outside of cardiothoracic procedures, has limited value in predicting postoperative pulmonary complications and should be limited to the confirmation of undiagnosed obstructive pulmonary disease (241).


Gynecology_Novak

Gynecology_Novak. Chronic Obstructive COPD is the greatest risk factor for the development of postoperative pulmonary com-Pulmonary Disease plications. COPD encompasses both chronic bronchitis and emphysema, disease entities that often occur in tandem. Cigarette smoke is implicated in the pathogenesis of both, and any treatment plan must include cessation of smoking (242). Chronic bronchitis is defined as the presence of productive cough on most days for at least 3 months per year and for at least 2 successive years (243). It is characterized by chronic airway inﬂammation and excessive mucus production. The histologic changes of emphysema include destruction of alveolar septa and distension of airspaces distal to terminal alveoli. The destruction of alveoli results in air trapping, loss of pulmonary elastic recoil, collapse of the airways in expiration, increased work of breathing, and significant ventilation-perfusion mismatching (243). The impaired ability to cough effectively and clear secretions


Gynecology_Novak

Gynecology_Novak. recoil, collapse of the airways in expiration, increased work of breathing, and significant ventilation-perfusion mismatching (243). The impaired ability to cough effectively and clear secretions predisposes patients with COPD to atelectasis and pneumonia in the postoperative period.


Gynecology_Novak

Gynecology_Novak. Patients with COPD and a history of heavy smoking account for most postoperative pulmonary complications in gynecologic surgical patients. The severity of COPD can be determined preoperatively via a thorough history and physical examination. According to recommendations regarding the use of preoperative pulmonary function tests by the American College of Physicians, these should be reserved for individuals in whom COPD is suspected, but unconfirmed (237,241). Typically, patients with COPD demonstrate impaired expiratory air ﬂow, manifested by diminished FEV1, forced vital capacity (FVC). Data suggest that arterial blood gas measurements may show varying degrees of hypoxemia and hypercapnia: routine use of preoperative arterial blood gas measurement does not stratify patients into a higher risk subset for postoperative complications (236).


Gynecology_Novak

Gynecology_Novak. The preoperative preparation of the patient at risk for postoperative pulmonary complications should include cessation of smoking for as long as possible preoperatively; whereas 2 to 3 days of smoking abstinence are sufficient for carboxyhemoglobin levels to return to normal. One to 2 weeks of cessation decreases sputum volume. Two months of smoking abstinence is required to significantly lower the risk of postoperative pulmonary complications (236). Longer periods of abstinence can be counseled in patients undergoing elective surgery.


Gynecology_Novak

Gynecology_Novak. In patients with severe COPD, maximum improvement in airﬂow limitation can be achieved with a therapeutic trial of high-dose oral corticosteroids followed by a 2-week trial of high-dose inhaled steroid (beclomethasone 1.5 mg per day or the equivalent) in addition to inhaled bronchodilator therapy. Ideally, oral and inhaled steroid therapy should be initiated 1 to 2 weeks preoperatively. Inhaled steroids, in particular, address the inﬂammatory component of COPD. Oral steroid therapy initiated preoperatively should be maintained throughout the perioperative period and then tapered postoperatively. Beta-adrenergic agonist therapy can be initiated at least 72 hours preoperatively and is beneficial in patients who demonstrate either clinical or spirometric improvement on bronchodilators.


Gynecology_Novak

Gynecology_Novak. Patients with COPD and an active bacterial infection suggested by purulent sputum should undergo a full course of antibiotic therapy before surgery. The antibiotic used should cover the most likely etiologic organisms, Streptococcus pneumoniae and Haemophilus inﬂuenzae. In any patient with acute upper respiratory infection, surgery should be delayed if possible. The use of antibiotics to sterilize the sputum in the absence of evidence of an acute infection should be avoided because this practice may lead to bacterial resistance. Aggressive pulmonary toilet, including incentive spirometry, chest physical therapy, and continuous positive airway pressure devices, reduced the risk of perioperative pulmonary complications in patients undergoing upper abdominal surgery, many of which can be instituted preoperatively (237).


Gynecology_Novak

Gynecology_Novak. Atelectasis accounts for more than 90% of all postoperative pulmonary complications. The pathophysiology involves a collapse of the alveoli, resulting in ventilation-perfusion mismatching, intrapulmonary venous shunting, and a subsequent drop in the PaO2. Collapsed alveoli are susceptible to superimposed infection, and if managed improperly, atelectasis will progress to pneumonia. Patients with atelectasis have a decreased FRC as well as decreased lung compliance, resulting in increased work during breathing. Despite the decrease in PaO2, the partial pressure of carbon dioxide (PCO2) remains unaffected unless atelectatic changes progress to large volumes of the lung or preexisting lung disease is present.


Gynecology_Novak

Gynecology_Novak. Physical findings associated with atelectasis may include a low-grade fever. Auscultation of the chest may reveal decreased breath sounds at the bases or dry rales upon inspiration. Percussion of the posterior thorax may suggest elevation of the diaphragm. Radiologic findings include the presence of horizontal lines or plates on posteroanterior chest x-rays, occasionally with adjacent areas containing hyperinﬂation. These changes are most pronounced during the first 3 postoperative days.


Gynecology_Novak

Gynecology_Novak. Therapy for atelectasis should be aimed at expanding the alveoli and increasing the FRC. The most important maneuvers are those that promote maximal inspiratory pressure, which is maintained for as long as possible. This exercise promotes an expansion of the alveoli and secretion of surfactant, which stabilizes alveoli. It can be achieved with aggressive supervised use of incentive spirometry, deep breathing exercises, coughing, and in some cases, the use of positive expiratory pressure with a mask (continuous positive airway pressure). Oversedation should be avoided, and patients should be encouraged to ambulate and change positions frequently. Fiberoptic bronchoscopy for removal of mucopurulent plugs should be reserved for patients who fail to improve with the usual measures.


Gynecology_Novak

Gynecology_Novak. Cardiogenic pulmonary edema can result from myocardial ischemia, myocardial infarction, or from intravascular volume overload, particularly in patients who have low cardiac reserve or renal failure. The process usually begins with an increase in the ﬂuid in the alveolar septa and bronchial vascular cuffs, ultimately seeping into the alveoli. Complete filling of the alveoli impairs secretion and production of surfactant. Concomitant with alveolar ﬂooding, there is a decrease in lung compliance, impairment of the oxygen diffusion capacity, and an increase in the arteriolar–alveolar oxygen gradient. Ventilation-perfusion mismatching in the lung results in a decrease in the PaO2, resulting eventually in decreased oxygenation of the tissues and impairment of cardiac contractility.


Gynecology_Novak

Gynecology_Novak. Symptoms may include tachypnea, dyspnea, wheezing, and use of the accessory muscles of respiration. Clinical signs may include distention of the jugular veins, peripheral edema, rales upon auscultation of the lungs, and an enlarged heart. Radiographic findings may include the presence of bronchiolar cuffing and increased interstitial ﬂuid markings extending to the periphery of the lung. The diagnosis can be confirmed with the use of central hemodynamic monitoring, which will denote an elevated central venous pressure and, more specifically, an elevation in the pulmonary capillary wedge pressure.


Gynecology_Novak

Gynecology_Novak. The patient’s volume status should be evaluated thoroughly. In addition, myocardial ischemia or infarction should be ruled out by performing ECG and analyzing cardiac enzyme levels. The management of cardiogenic pulmonary edema includes oxygen support, aggressive diuresis, and afterload reduction to increase the cardiac output. In the absence of myocardial infarction, an inotropic agent may be used. Mechanical ventilation should be reserved for cases of acute respiratory failure.


Gynecology_Novak

Gynecology_Novak. In contrast with cardiogenic pulmonary edema, in which alveolar ﬂooding is a result of an increase in the hydrostatic pressure of the pulmonary capillaries, alveolar ﬂooding in patients with adult respiratory distress syndrome (ARDS) is the result of an increase in pulmonary capillary permeability. The primary pathophysiologic process is one of damage to the capillary side of the alveolar–capillary membrane. This damage results in rapid movement of ﬂuid containing high concentrations of protein from the capillaries to the pulmonary parenchyma and alveoli. Lung compliance decreases and oxygen diffusion capacity is impaired, resulting in hypoxemia. If not managed aggressively, respiratory failure may result; when managed aggressively, the mortality rate associated with ARDS is high. There are a number of causes and several distinct states of ARDS. The causes of ARDS include shock, sepsis, multiple red blood cell transfusions, aspiration injury, inhalation injury, pneumonia,


Gynecology_Novak

Gynecology_Novak. There are a number of causes and several distinct states of ARDS. The causes of ARDS include shock, sepsis, multiple red blood cell transfusions, aspiration injury, inhalation injury, pneumonia, pancreatitis, disseminated intravascular coagulation, and fat emboli (244). Twenty-eight-day mortality is reported between 25% to 40%, with overall mortality as high as 70% (244,245). Irrespective of the cause, which should be identified and treated if possible, the evolving clinical picture and management are very similar.


Gynecology_Novak

Gynecology_Novak. Clinically, ARDS passes through several stages. Initially, patients develop tachypnea and dyspnea with no remarkable findings on clinical evaluation or on chest x-ray. Chest x-rays eventually reveal bilateral diffuse pulmonary infiltrates. As lung compliance becomes impaired, functional residual capacity, tidal volume, and vital capacity decrease. The PaO2 decreases and, characteristically, increases only marginally with oxygen supplementation. An attempt should be made to maintain the arterial oxygen level above 90%. This may be achievable initially by administering oxygen by mask. For patients with severe hypoxemia, endotracheal intubation with positive-pressure ventilation should be instituted. Traditionally, the goal was to maintain normal arterial gases, with increased minute ventilation and pressure as needed to maintain these, with little insight into the long-term repercussions that this modality employs. Data over the past 5 to 10 years show that “normal” or increased tidal


Gynecology_Novak

Gynecology_Novak. and pressure as needed to maintain these, with little insight into the long-term repercussions that this modality employs. Data over the past 5 to 10 years show that “normal” or increased tidal volumes and pressures are linked to significant barotrauma and injury to alveoli. Elevated positive end-expiratory pressure (PEEP) increasingly was used to recruit alveoli, with decreases in the amount of fraction of inspired oxygen (Fio2) and minute ventilation required to maintain oxygenation in this setting, with limited success when compared to lower PEEP levels, controlling for tidal volume and end-inspiratory pressures (246).


Gynecology_Novak

Gynecology_Novak. Attempts to manage and treat the cause of ARDS must include aggressive efforts toward hemodynamic and circulatory resuscitation in patients with shock. Nosocomial pneumonia is present in 50% of patients with ARDS, and broad-spectrum antibiotic therapy should be administered appropriately for patients with suspected pneumonia or sepsis. Patients who have disseminated intravascular coagulopathy may require replacement with cryoprecipitate or FFP. Other measures for general care should include the placement of a nasogastric tube, gastric acid suppression with H2 blockers, and administration of steroids in patients with the fat emboli syndrome.


Gynecology_Novak

Gynecology_Novak. Hemodynamic monitoring is invaluable and should be initiated early in the course of the disease process in the appropriate intensive care unit setting. Patients with any evidence of ﬂuid overload should receive aggressive diuresis, whereas others may require ﬂuid resuscitation for maintenance of tissue perfusion while the pulmonary–capillary wedge pressure is maintained below 15 mm Hg. Pulmonary wedge pressure may be falsely elevated when PEEP is being applied. The goal of management is to maintain the lowest pulmonary–capillary wedge pressure, with acceptable cardiac output and blood pressure. In the setting of hypotension and oliguria, inotropic support with dopamine or dobutamine or both is helpful.


Gynecology_Novak

Gynecology_Novak. With aggressive management, particularly if the inciting cause is identified and treated, ARDS can be reversed during the first 48 hours with few sequelae. After the first 48 hours, progression of the ARDS will cause lung damage that may leave residual pulmonary fibrosis. The long-term outcome is usually apparent within the first 10 days, at which time approximately half of patients are weaned from ventilatory support or they die (244).


Gynecology_Novak

Gynecology_Novak. Renal Disease The need for surgical intervention in patients with renal impairment resulted in the development of a very specialized medical approach to their care. Precautions are necessary to compensate for the kidneys’ impaired ability to regulate ﬂuids and electrolytes and excrete metabolic waste products. Equally important are the unique problems that develop in patients with chronic renal impairment, including an increased risk of sepsis, coagulation defects, impaired immune function and wound healing, and a propensity to develop specific acid-base abnormalities. Special consideration must be given to a variety of different medications, anesthetic agents, and numerous hematologic and nutritional factors that are important in the successful surgical care of patients with renal insufficiency.


Gynecology_Novak

Gynecology_Novak. Management of ﬂuid levels and cardiovascular hemodynamics in patients with acute or chronic renal impairment is paramount. Intravascular ﬂuid volume changes that lead to hypertension or hypotension are very common in these patients and often are difficult to manage secondary to autonomic dysfunction, acidosis, and other problems that are inherent to the underlying kidney disease. Patients undergoing dialysis in whom major abdominal or pelvic surgery is contemplated should be treated using invasive monitoring, both intra-and postoperatively. The results of physical examination and CVP monitoring correlate poorly with left cardiac filling pressures. Swan-Ganz catheter measurements will help guide ﬂuid replacement and avoid volume overload. Invasive hemodynamic monitoring should be continued as needed throughout the first postoperative week because third spacing will occur during this period.


Gynecology_Novak

Gynecology_Novak. Postoperative dialysis usually is necessary to avoid problems associated with ﬂuid overload and hyperkalemia. Dialysis-dependent patients should undergo dialysis approximately 24 hours following surgery. A short-lived but rather significant fall in the number of platelets occurs during dialysis; in addition, heparin is used in hemodialysis equipment to prevent clotting. Because of these factors and concerns about postoperative bleeding, dialysis is usually avoided during the first 12 to 24 hours following surgery. Although ischemic heart disease is the most common cause of death in patients with renal insufficiency, it is not a major cause of perioperative mortality (247). A large percentage of perioperative deaths of patients with renal insufficiency are associated with hyperkalemia that is controlled most effectively by dialysis (248).


Gynecology_Novak

Gynecology_Novak. Patients with chronic renal failure are at an increased risk for postoperative infections resulting from abnormalities in neutrophil and monocyte function (249). Appropriate preoperative antibiotic prophylaxis and accurate assessment of nutritional status help lower the incidence of postoperative infectious complications.


Gynecology_Novak

Gynecology_Novak. The major hematologic concern in patients with chronic renal insufficiency is the increased incidence of bleeding. These bleeding problems are secondary to abnormal bleeding times and, in particular, disorders of platelet function related to a decreased amount of factor VIII and von Willebrand antigen in the serum of uremic patients. Anemia, which is common in patients with renal insufficiency, can contribute to prolonged bleeding times (250). Abnormalities in arachidonic acid metabolism, acquired platelet storage pool deficiency, and disturbed regulation of platelet calcium content all contribute to an increased tendency for uremic patients to have significant bleeding during surgery (251). The bleeding time should be routinely checked preoperatively in these patients, and abnormalities should be corrected before surgery. Options for the correction of bleeding time in uremic patients include infusion of desmopressin or cryoprecipitate, both of which act to increase plasma levels of


Gynecology_Novak

Gynecology_Novak. should be corrected before surgery. Options for the correction of bleeding time in uremic patients include infusion of desmopressin or cryoprecipitate, both of which act to increase plasma levels of factor VIII and von Willebrand antigen (252,253).


Gynecology_Novak

Gynecology_Novak. Normal renal function is essential for maintenance of acid-base balance in the body. Patients with renal insufficiency can have a normal anion gap or an elevated anion gap acidosis. When mild renal insufficiency develops, a normal anion gap is present, whereas in more significant and severe renal dysfunction, an elevated anion gap acidosis occurs. Hemodialysis corrects metabolic acidosis. If a patient is severely acidotic (pH <7.15) and emergency surgery is planned, correction of the blood pH to 7.25 using intravenous sodium bicarbonate is indicated. However, correction of metabolic acidosis should be carried out slowly, because in patients with hypocalcemia, seizures may be precipitated (254). It is important to exclude other causes of elevated anion gap acidosis, such as ketoacidosis secondary to diabetes, lactic acidosis secondary to infection, or in rare instances, poisoning with ethylene glycol, methanol, or aspirin.


Gynecology_Novak

Gynecology_Novak. Impaired kidney function causes phosphate retention by the kidney and impaired vitamin D metabolism. Therefore, hypocalcemia is common in patients with renal insufficiency, but tetany and other signs of hypocalcemia are relatively uncommon because metabolic acidosis increases the level of ionized calcium. Oral phosphate binders, such as aluminum hydroxide (1 to 2 g per meal), and dietary phosphate restriction (1 g per day) is the usual treatment for hypocalcemia– hyperphosphatemia in patients with renal insufficiency. In chronic situations, because of central nervous system toxicity associated with elevated aluminum levels, it is preferable to treat hypocalcemia–hyperphosphatemia with large doses of calcium carbonate (6 to 12 g per day) rather than with the standard aluminum-containing antacids (255).


Gynecology_Novak

Gynecology_Novak. Approximately 20% of patients with renal insufficiency exhibit clinical evidence of protein calorie malnutrition. Vitamin deficiencies, most notably with water-soluble vitamins, occur with dialysis. Nutritional disturbances in patients with chronic renal insufficiency arise secondary to deficiencies in protein intake, and studies show that, in patients with chronic renal insufficiency, their kidneys are hyperfiltrating (256). Postoperatively, both protein and caloric intake may need to be increased dramatically to meet catabolic demands in surgical patients. As much as 1.5 g/kg of protein and 45 kcal/kg of calories may be needed (256).


Gynecology_Novak

Gynecology_Novak. Wound healing is impaired in patients with chronic renal failure, and wound dehiscence and evisceration are potential problems. Wound healing is most appropriately aided by nutritional assessment preoperatively and maintenance of adequate caloric and protein intake in the perioperative setting. Antibiotic prophylaxis should be used in these patients, and uremia should be treated with dialysis as indicated. A running mass closure of the midline vertical incision with continuous monofilament sutures should be used to decrease the risk of wound dehiscence and evisceration (256).


Gynecology_Novak

Gynecology_Novak. Patients with chronic renal disease have an altered ability to excrete drugs and are prone to significant metabolic derangements secondary to the altered bioavailability of many commonly used medications. Because of this, and the effect of dialysis on drug pharmacokinetics, the gynecologic surgeon and nephrologist must be aware of the lowered metabolism and bioavailability of narcotics, barbiturates, muscle relaxants, antibiotics, and other drugs that require renal clearance. Of particular note is the inability of patients with renal insufficiency to clear the neuromuscular blockade caused by pancuronium (257). Care must be taken with D-tubocurarine, especially if repeated doses are given (258). Midazolam, propofol, vecuronium, and atracurium are used safely in patients with renal failure (254). Succinylcholine is reported to cause significant hyperkalemic responses in patients with renal failure (259). When succinylcholine is used in patients with chronic renal insufficiency, careful


Gynecology_Novak

Gynecology_Novak. (254). Succinylcholine is reported to cause significant hyperkalemic responses in patients with renal failure (259). When succinylcholine is used in patients with chronic renal insufficiency, careful monitoring of the serum potassium level is necessary (260).


Gynecology_Novak

Gynecology_Novak. Perioperative acute renal failure in previously normal patients may be caused by decreased renal perfusion, nephrotoxins, or both. Patients with impaired cardiac function, intravascular volume depletion, sepsis, or hypotension fall under the first category. Nephrotoxic medications such as aminoglycosides, chemotherapeutic agents such as cisplatin, or iodinated contrast agents fall under the second category (261–263). The risk of renal impairment becomes cumulative if more than one of these factors exist at the same time, and especially if a variety of factors are associated with intervascular volume depletion (264). Several measurements should be used to avoid acute renal failure. All nephrotoxic drugs should be discontinued when possible. When it is not practical to withdraw medication, strict attention should be paid to the pharmacokinetic characteristics of each drug and to the regular measurements of serum creatinine levels. Patients with diabetes should be given reduced doses of


Gynecology_Novak

Gynecology_Novak. strict attention should be paid to the pharmacokinetic characteristics of each drug and to the regular measurements of serum creatinine levels. Patients with diabetes should be given reduced doses of radiocontrast agents and should be well hydrated because they are particularly susceptible to renal injury from these materials (265). Volume repletion is essential to lower the incidence of renal impairment (266).


Gynecology_Novak

Gynecology_Novak. Laboratory Testing The biochemical profile (alkaline phosphatase, calcium, lactate dehydrogenase, bilirubin, serum glutamic–oxaloacetic transaminase, cholesterol, uric acid, phosphorous, albumin, total protein, and glucose) is not useful for routine preoperative evaluation (267). Mild abnormalities can result in further extensive testing that requires consultation, delays in surgery, and increased cost without net benefit. A possible exception is selected use of biochemical testing when the history or physical examination reveals abnormalities. Patients with known liver disease should undergo albumin and bilirubin testing using the Child’s risk classification (Table 22.21). This system


Gynecology_Novak

Gynecology_Novak. Table 22.21 Child’s Classification of Liver Dysfunction was originally designed to predict mortality following portosystemic shunt surgery. It divides patients into three classes of severity based on five easily assessed clinical parameters. Measurement of prothrombin time may be helpful in patients with significant histories of liver disease. If a history of hepatitis is ascertained, the patient should be tested for serum aminotransferase, alkaline phosphatase, bilirubin, albumin levels, and prothrombin time. Serologic documentation of hepatitis is important. If a patient has a known malignancy, biochemical testing of the liver may be of some benefit as a screen for metastatic disease, although this was not proven conclusively.


Gynecology_Novak

Gynecology_Novak. Anesthesia With few exceptions, most anesthetic agents, including those administered by epidural or spinal routes, reduce hepatic blood ﬂow and decrease oxygenation of the liver. Other perioperative factors—hemorrhage, intraoperative hypotension, hypercarbia, congestive heart failure, and intermittent positive pressure ventilation, especially in critically ill patients—lead to decreased hepatic perfusion and hypoxia (268).


Gynecology_Novak

Gynecology_Novak. Drug Metabolism Patients with altered liver function should be carefully monitored because of the prolonged action of many medications used during surgery. In addition to impaired metabolism, hypoalbuminemia decreases drug binding, which alters serum levels and biliary clearance rates. The degree of hepatic metabolism varies greatly, depending on the type of medication considered. For inhalation anesthetics, isoﬂurane is preferred because it undergoes minimal hepatic metabolism in comparison with halothane or enﬂurane. Narcotics, induction agents, sedatives, and neuromuscular blocking agents all undergo abnormal metabolism in patients with decompensated liver disease. Diazepam, meperidine, and phenobarbital cause prolonged depression of consciousness and may precipitate hepatic encephalopathy because of their altered rates of clearance. Sufentanil and fentanyl are the preferred narcotics. Oxazepam, a benzodiazepine that does not undergo hepatic metabolism, is considered safe. Muscle