What's new in small animal veterinary anesthesia? (Proceedings)

Nov 01, 2010

The purpose of this presentation is to review several articles published in veterinary journals over the last three years and to present them in a way that is relevant to the practicing veterinarian.

Mortality and CPCR: Obviously, the veterinarian wants to avoid anesthetic-related mxortality. The only way to effectively do that is to understand the factors associated with anesthetic mishaps. The three articles summarized below provide some valuable information of the practitioner:

Brodbelt et al. The risk of death: the confidential enquiry into perioperative small animal fatalities. Vet Anaes Analg 2008.

What they did: The authors performed a prospective case-control stud of anesthetic-related mortality in 117 veterinary practices and evaluated nearly 100,000 dogs, 80,000 cats, and 8,200 rabbits. They evaluated deaths that occurred within 48 hours of anesthesia or sedation.

What they found:

     o The overall death rate for dogs, cats, and rabbits was 0.17%, 0.24%, and 1.39%, respectively.
     o The risk was lower in healthy animals (0.05, 0.11, and 0.73%)
     o Postoperative deaths accounted for 7, 61, and 64% of deaths in dogs, cats, and rabbits, respectively. The first three hours after anesthesia was the most critical.
     o Risk of death associated with sedation was less than for anesthesia. (Maybe???)
     o Most deaths in dogs and cats were related to cardiovascular or respiratory causes. Most deaths in rabbits were of unknown cause.

What you need to know: This comprehensive study proved a few things that we already suspected (sicker animals are at higher risk for anesthetic death), and perhaps revealed a few things that we didn't know. For example, the first three hours after the end of anesthesia were associated with a significant percentage of anesthesia related deaths. This implies that we need to assess our patients more aggressively in the immediate postoperative period. The risk of anesthetic-related death is higher in cats than in dogs, and it appears that the risk of death from sedation alone MAY NOT be different from the risk associated with general anesthesia.

Hofmeister et al. Prognostic indicators for dogs and cats with cardiopulmonary arrest (CPA) treated by cardiopulmonary cerebral resuscitation (CPCR) at a university teaching hospital. JAVMA 2009.

What they did:

The authors reviewed records from all animals that suffered CPA during a 60 month period .

What they found:

     o 6% of the animals that had in-hospital CPA survived to discharge. (35% of dogs and 44% of cats had a return of spontaneous circulation—successful CPCR).
     o Successful resuscitation was more likely if:
     o The dog was anesthetized at the time of CPA
     o The duration of CPA was short
     o Multiple diseases/conditions were not present
     o The following drugs were used: mannitol, lidocaine, fluids, dopamine, corticosteroids, vasopressin
     o Cardiac massage was done in lateral recumbence
     o None of the animals that arrested outside of the hospital survived to discharge.
     o Higher levels of CO2 as determined by capnography were associated with successful resuscitation (dogs and catswith a peak CO2 reading less than 15 or 20 mm Hg, respectively, were unlikely to have a return of spontaneous circulation).
     o In cats, more people involved in the resuscitation was a positive predictor of outcome. Shock prior to arrest was a negative predictor of outcome.
     o 50% of the dogs arrested in asystole, 23% had bradycardia

What you need to know:

     o CPCR is not a practice builder!!! It has a low success rate
     o Your capnograph is a good tool to help monitor your patient during CPCR