Cardiopulmonary effects of three prolonged periods of isoflurane anesthesia in an adult elephant.

An adult 3,500-kg female African elephant was anesthetized 3 times for treatment of subcutaneous fistulas over the lateral aspect of each cubitus (anesthesia 1 and 2) and for repair of a fractured tusk (anesthesia 3). Lateral recumbency and anesthesia were achieved with etorphine (anesthesia 1 and 2) or etorphine and azaperone (anesthesia 3). The elephant's trachea was intubated and anesthesia was maintained by use of isoflurane and oxygen delivered via 2 standard large animal anesthesia machines joined in parallel. The range of total recumbency time was 2.4 to 3.3 hours. Breathing and heart rates, systemic arterial pressure, rectal temperature, PaO2, pH, and end-tidal gases were monitored. After administration of etorphine, measurements were made while the air-breathing elephant was recumbent, then every 5 minutes (cardiovascular) or 15 minutes (blood gases) after commencement of administration of isoflurane and oxygen. Tachycardia and hypertension were detected after administration of etorphine, but heart rate and systemic arterial pressure decreased to within normal ranges after administration of isoflurane and oxygen. The elephant remained well oxygenated while anesthetized and breathing a high oxygen mixture. The elephant had an uneventful recovery from each anesthesia.