Comparison of cardiovascular function and quality of recovery in isoflurane-anaesthetised horses administered a constant rate infusion of lidocaine or lidocaine and medetomidine during elective surgery.
BACKGROUND
The effects of lidocaine combined with medetomidine or lidocaine alone on cardiovascular function during anaesthesia and their effects on recovery have not been thoroughly investigated in isoflurane-anaesthetised horses.


OBJECTIVE
To determine the effects of an intraoperative i.v. constant rate infusion of lidocaine combined with medetomidine (Group 1) or lidocaine (Group 2) alone on cardiovascular function and on the quality of recovery in 12 isoflurane-anaesthetised horses undergoing arthroscopy.


OBJECTIVE
The combination would depress cardiovascular function but improve the quality of recovery when compared to lidocaine alone in isoflurane-anaesthetised horses.


METHODS
Lidocaine (2 mg/kg bwt i.v. bolus followed by 50 microg/kg bwt/min i.v.) or lidocaine (same dose) and medetomidine (5 microg/kg bwt/h i.v.) was started 30 min after induction of anaesthesia. Lidocaine administration was discontinued 30 min before the end of surgery in both groups, whereas medetomidine administration was continued until the end of surgery. Cardiovascular function and quality of recovery were assessed.


RESULTS
Horses in Group 1 had longer recoveries, which were of better quality due to better strength and overall attitude during the recovery phase than those in Group 2. Arterial blood pressure was significantly higher in Group 1 than in Group 2 and this effect was associated with medetomidine. No significant differences in cardiac output, arterial blood gases, electrolytes and acid-base status were detected between the 2 groups.


CONCLUSIONS
The combination of an intraoperative constant rate infusion of lidocaine and medetomidine did not adversely affect cardiovascular function in isoflurane-anaesthetised horses and improved the quality of recovery when compared to an intraoperative infusion of lidocaine alone.
Valverde
A
A
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Rickey
E
E
Sinclair
M
M
Rioja
E
E
Pedernera
J
J
Hathway
A
A
Cruz
A
A
D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000662:veterinary; D018681:Anesthetics, General / Q000008:administration & dosage / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004359:Drug Therapy, Combination; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006736:Horses; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000494:pharmacology; D008012:Lidocaine / Q000008:administration & dosage* / Q000494:pharmacology*; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage* / Q000494:pharmacology*
D018681:Anesthetics, General; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008012:Lidocaine; D007530:Isoflurane; D020926:Medetomidine