The cardiac anesthetic index of isoflurane in green iguanas.
OBJECTIVE
To determine the cardiac anesthetic index (CAI) of isoflurane in green iguanas and whether butorphanol affected the CAI.


METHODS
Prospective randomized controlled trial.


METHODS
7 healthy mature iguanas.


METHODS
In 5 iguanas, CAI was determined after induction of anesthesia with isoflurane alone, and in 5 iguanas, CAI was determined after induction of anesthesia with isoflurane and IM administration of butorphanol (1 mg/kg [0.45 mg/lb]). Three iguanas underwent both treatments. Animals were equilibrated for 20 minutes at 1.5 times the minimum alveolar concentration (MAC) of isoflurane and observed for evidence of cardiovascular arrest. If there was no evidence of cardiovascular arrest, end-tidal isoflurane concentration was increased by 20%, and animals were allowed to equilibrate for another 20 minutes. This process was repeated until cardiovascular arrest occurred or vaporizer output could no longer be consistently increased. The CAI was calculated by dividing the highest end-tidal isoflurane concentration by the MAC.


RESULTS
None of the iguanas developed cardiovascular arrest and all survived. Mean +/- SD highest end-tidal isoflurane concentration during anesthesia with isoflurane alone (9.2 +/- 0.60%) was not significantly different from mean concentration during anesthesia with isoflurane and butorphanol (9.0 +/- 0.43%). The CAI was > 4.32.


CONCLUSIONS
Results suggest that the CAI of isoflurane in green iguanas is > 4.32 and not affected by administration of butorphanol. Isoflurane appears to be a safe anesthetic in green iguanas.
Mosley
Craig A E
CA
Department of Clinical Studies , Ontario Veterinary College, University of Guelph, Guelph, ON, Canada NIG 2W1.
Dyson
Doris
D
Smith
Dale A
DA
D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000758:Anesthesia / Q000379:methods / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000378:metabolism*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007076:Iguanas / Q000378:metabolism / Q000502:physiology*; D007530:Isoflurane / Q000378:metabolism*; D008297:Male; D011446:Prospective Studies; D011897:Random Allocation; D012119:Respiration / Q000187:drug effects
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D002077:Butorphanol