Arrhythmias Associated with Isoflurane Anesthesia in Bald Eagles (Haliaeetus leucocephalus)

Apnea, cardiac arrhythmias, and sudden death occur occasionally in raptors when isoflurane is used as the sole anesthetic agent. Twelve bald eagles (Haliaeetus leucocephalus) were each subjected to two 30-min sessions of anesthesia in which isoflurane was the sole anesthetic agent. Electrocardiograms were obtained before induction and after 30 min of anesthesia. Continuous lead II electrocardiographic monitoring was initiated before induction and continued until after recovery. Pulse and O₂ saturation were monitored on all birds with a plethysmograph. Continuous gas flow was monitored following intubation with a sidestream gas analyzer. In five randomly selected birds, 1 ml of venous blood was drawn at predetermined intervals from the ulnar vein into a syringe and refrigerated for subsequent blood gas and electrolyte analysis. Levels of venous O₂, Pco₂, potassium, and pH were determined for each sample. In the same five birds, mean arterial and systolic blood pressures were monitored indirectly every 3 min. Temperatures were measured at the same intervals as those used for blood sampling. Arrhythmias were observed in 75% of the eagles and occurred during periods of induction or recovery in 80% of the cases. Though hypercarbia was suspected as a contributing factor, paired sample t-test analysis of measured data failed to indicate causality.