Anesthetic management of an off-pump open-heart surgery in a dog.
Surface-induced hypothermia is used to protect tissues from ischemic events during surgery. In a review of 19 clinical cases in dogs, the technique was used to enable intracardiac surgery (4 dogs) and to facilitate removal of extensive thoracic or abdominal masses (15 dogs). For 16 dogs (84%), anesthesia was induced with an opioid/benzodiazepine combination and maintained with a balanced technique by use of an opioid, a neuromuscular blocking agent, and isoflurane in oxygen. Dogs were cooled in an ice bath to a mean esophageal temperature of 27.8 +/- 1.4 C. Mean anesthesia time was 4.04 +/- 1.37 hours. Hypothermic-induced adverse effects, such as increased blood viscosity, increased myocardial irritability, and shivering, were managed by hemodilution, manipulation of acid-base balance, and administration of opioid and neuromuscular blocking agents. Complications requiring treatment included severe hypotension (74%), arrhythmias (47%), hypoxemia (42%), and acidemia (58%). Six dogs (32%) went into cardiac arrest and all were successfully resuscitated once the surgical procedure was completed. One dog was euthanatized during surgery, another died after surgery, and the 17 remaining dogs (90%) were discharged from the hospital to their owners. The technique appears beneficial in selected cases to decrease the morbidity and mortality associated with the risk of prolonged ischemia and life-threatening hemorrhage.