Minimum alveolar concentration of isoflurane in green iguanas and the effect of butorphanol on minimum alveolar concentration.
OBJECTIVE
To determine minimum alveolar concentration (MAC) of isoflurane in green iguanas and effects of butorphanol on MAC.


METHODS
Prospective randomized trial.


METHODS
10 healthy mature iguanas.


METHODS
in each iguana, MAC was measured 3 times: twice after induction of anesthesia with isoflurane and once after induction of anesthesia with isoflurane and IM administration of butorphanol (1 mg/kg [0.45 mg/lb]). A blood sample was collected from the tail vein for blood-gas analysis at the beginning and end of the anesthetic period. The MAC was determined with a standard bracketing technique; an electrical current was used as the supramaximal stimulus. Animals were artificially ventilated with a ventilator set to deliver a tidal volume of 30 mL/kg (14 mL/lb) at a rate of 4 breaths/min.


RESULTS
Mean +/- SD MAC values during the 3 trials (2 without and 1 with butorphanol) were 2.0 +/- 0.6, 2.1 +/- 0.6, and 1.7 +/- 0.7%, respectively, which were not significantly different from each other. Heart rate and end-tidal partial pressure of CO2 were also not significantly different among the 3 trials. Mean +/- SD heart rate was 48 +/- 10 beats/min; mean end-tidal partial pressure of CO2 was 22 +/- 10 mm Hg. There were no significant differences in blood-gas values for samples obtained at the beginning versus the end of the anesthetic period.


CONCLUSIONS
Results suggest that the MAC of isoflurane in green iguanas is 2.1% and that butorphanol does not have any significant isoflurane-sparing effects.
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*; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics*; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002077:Butorphanol / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D004347:Drug Interactions; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007076:Iguanas / Q000378:metabolism*; D007530:Isoflurane / Q000493:pharmacokinetics*; D008297:Male; D010313:Partial Pressure; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*; D011897:Random Allocation
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D002077:Butorphanol