A patient previously diagnosed with COPD comes to the emergency room for 3 days with increased dyspnea until he is at rest, cough with whitish expectoration and marked drowsiness. After receiving treatment with oxygen at low concentrations, bronchodilators and coticoids, a second arterial blood gas with 28% inspiratory oxygen fraction shows a pH of 7.32, pO2 61 mmHg, pCO2 58 mmHg, HCO3- 29 mmol/l. What would be the interpretation you would make of the arterial blood gas and what treatment would you use?
This is a very bad question, I will bet on one answer, but depending on data that we are not given, three answers could be valid. The trap is that they give us the initial clinical picture WITHOUT GASOMETRY and then they give us the blood gases afterwards WITHOUT CLINIC, so there is no way of knowing what the evolution of the patient has been with our treatment, so it is impossible to know what to do. If the patient initially came with a blood gas with a pH of 7.05 and now has the one we are given, we are doing well (although we are not told the time interval between one thing and the other) and, in this case, it could be worthwhile to continue with the same treatment. If nothing has evolved, the clinical picture is the same and the blood gas at the beginning was similar, something should be done (also depending on the patient's baseline status, which they do not tell us either). If we decide to do something, at present we might decide to use ventilation rather than theophylline, although with "so little" alteration of pH (and even more so if we think that this is a chronic patient who may have a baseline blood gas similar to the one presented to us) it may seem "exaggerated". We have nothing "against" theophylline (we are not told of any contraindication), but nowadays it is rare to resort to it. 1: Wrong, he is a "retentive" patient and increasing O2 flow is highly likely to increase hypercapnia and, therefore, acidosis. 2: We will keep this one as correct. 3: It is not a metabolic acidosis, the bicarbonate is not decreased, on the contrary, it is slightly increased trying to compensate the respiratory acidosis. 4: He does not reach respiratory failure by definition (pO2 60), but he has hypercapnia and slight acidosis. If we knew the first blood gas and she was much worse (i.e. she was doing very well), continuing with the same medication would be an option, but this data is missing!!!, in any case it seems to be a trick answer. 5: At present and -as already mentioned- taking into account that there is no formal contraindication, it is not usually used.
Increase oxygen flow because he has acute respiratory acidosis and hypoxemia.
I would initiate noninvasive mechanical ventilation because he has acute hypercapnic respiratory failure with moderate respiratory acidosis.
I would add sodium bicarbonate to correct the acute metabolic acidosis.
The patient does not have respiratory insufficiency so he would continue with the same pharmacological regimen.
I would add intravenous aminophylline as a respiratory stimulant, since I appreciate hypoxemia and hypercapnia.
Wrong, he is a "retentive" patient and increasing O2 flow is highly likely to increase hypercapnia and, therefore, acidosis.
If we decide to do something, at present we might decide to use ventilation rather than theophylline, although with "so little" alteration of pH (and even more so if we think that this is a chronic patient who may have a baseline blood gas similar to the one presented to us) it may seem "exaggerated".
It is not a metabolic acidosis, the bicarbonate is not decreased, on the contrary, it is slightly increased trying to compensate the respiratory acidosis.
He does not reach respiratory failure by definition (pO2 60), but he has hypercapnia and slight acidosis.
At present and -as already mentioned- taking into account that there is no formal contraindication, it is not usually used.