Comparison of Induction and Recovery Characteristics and Cardiopulmonary Effects of Sevoflurane and Isoflurane in Bald Eagles (Haliaeetus leucocephalus)
Abstract
Due to reported isoflurane-associated arrhythmias in bald eagles (Haliaeetus leucocephalus),1 other anesthetics may be superior in this species. Sevoflurane and isoflurane were compared in 17 captive bald eagles in a crossover study. Anesthesia was rapidly induced via facemask with isoflurane (4%) and sevoflurane (7%) delivered in oxygen (1.5 L/min) and maintained via endotracheal tube at approximately 2.5 MAC for isoflurane (3.5%) and sevoflurane (5%). Time to induction, extubation, and recovery were recorded. Blood was collected via catheter from the ulnar artery for blood gas analyses performed at 10, 25, and 40 minutes post-intubation. Body temperature, heart rate, respiratory rate, oxygen saturation by pulse oximeter, end tidal CO2 (ETCO2), direct systolic, mean and diastolic blood pressures, and electrocardiograms were recorded every 5 minutes post-induction. Repeated measures ANOVA was used to test for main effects of treatment and time. Significance was defined as p<0.05.
Both isoflurane and sevoflurane resulted in a smooth, rapid induction to and recovery from anesthesia. Recovery time was significantly longer during isoflurane anesthesia versus sevoflurane. A significant decrease in respiratory rate over time occurred with both agents, while heart rate significantly decreased with sevoflurane only. Heart rate; ETCO2; and direct systolic, mean, and diastolic blood pressures were significantly higher during isoflurane anesthesia compared with sevoflurane anesthesia (Table 1). Arrhythmias were observed during isoflurane (5/17) and sevoflurane (4/17) anesthesia, and the types of arrhythmias were similar. Sevoflurane anesthesia had fewer side effects overall, suggesting sevoflurane may be preferable to isoflurane, especially in compromised bald eagles.
Table 1. Comparison of selected significantly different results
from isoflurane and sevoflurane anesthesia in bald eagles.
Values are reported as mean ± standard error
|
|
Isoflurane
|
Sevoflurane
|
|
Recovery time (sec)
|
326±64
|
195±63
|
|
Heart rate (beats/min)
|
266±15
|
241±15
|
|
ETCO2 (mm Hg)
|
53±8
|
28±8
|
|
Direct systolic blood pressure (mm Hg)
|
194±13
|
146±13
|
|
Direct diastolic blood pressure (mm Hg)
|
158±13
|
135±13
|
|
Direct mean blood pressure (mm Hg)
|
176±12
|
138±12
|
Acknowledgments
The authors thank the staff of the American Eagle Foundation, The Wildlife Center of Virginia and The University of Tennessee, Knoxville, College of Veterinary Medicine for their cooperation and assistance. We also thank Drs. T. Hadley, J.M. Sykes, and L. Brazelton for their assistance with data collection. This research was supported by the Morris Animal Foundation.
Literature Cited
1. Aguilar RF, Smith VE, Ogburn P, Redig PT. Arrhythmias associated with isoflurane anesthesia in bald eagles (Haliaeetus leucocephalus). J Zoo Wildl Med. 1995;26:508–516.