Effect of butorphanol administration on cardiovascular parameters in isoflurane-anesthetized horses - a retrospective clinical evaluation.
OBJECTIVE
To determine cardiovascular responses to administration of butorphanol in isoflurane-anesthetized horses.


METHODS
Retrospective evaluation of anesthetic records.


METHODS
Seventy-six horses anesthetized for a variety of clinical surgical procedures.


METHODS
Anesthetic records of clinical equine patients anesthetized between January 1999 and December 2003 were searched. The records were reviewed for horses in which anesthesia was induced with ketamine and a benzodiazepine and maintained with isoflurane, and horses that received butorphanol intraoperatively. Exclusion criteria included horses in which the rate of infusion of an inotrope or end-tidal isoflurane concentration was changed 10 minutes before or after the butorphanol bolus. The horses were separated into two groups: group 1 horses received butorphanol at intervals as part of a balanced protocol, group 2 horses had > or = 10% increase in heart rate (HR) or blood pressure within 10 minutes prior to butorphanol administration.


RESULTS
Eighty-nine butorphanol administration events matched the criteria for inclusion, 49 in group 1 and 40 in group 2. There were no significant changes after butorphanol administration in systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), and heart rate (HR) in group 1, or in end-tidal carbon dioxide concentration or hemoglobin oxygen saturation in either group. There were significant decreases in SAP (p < 0.0001), MAP (p < 0.0005), and DAP (p < 0.0008) after butorphanol administration in group 2.


CONCLUSIONS
The results presented here confirm that butorphanol can be administered to horses during isoflurane anesthesia without adverse effects on HR and arterial blood pressure. The results imply that butorphanol can deepen the plane of anesthesia and obtund sympathetic stimulation from a surgical procedure.
Hofmeister
Erik H
EH
Department of Small Animal Medicine & Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA. erikh@vet.uga.edu
Mackey
Elizabeth B
EB
Trim
Cynthia M
CM
D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000768:Anesthesia, General / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005845:Georgia; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000502:physiology* / Q000601:surgery; D007275:Injections, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage*; D008297:Male; D011996:Records; D012189:Retrospective Studies; D014730:Veterinary Medicine
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D002077:Butorphanol