Evaluation of the clinical efficacy of two partial intravenous anesthetic protocols, compared with isoflurane alone, to maintain general anesthesia in horses.
OBJECTIVE
To compare the ability of 2 partial IV anesthesia (PIVA) techniques to maintain anesthesia, compared with isoflurane alone, in horses.


METHODS
45 horses.


METHODS
Client-owned horses requiring general anesthesia for a variety of procedures of at least 1 hour's duration were randomly allocated to 3 groups (n = 15/group) that differed for the maintenance protocol. Anesthesia was maintained with isoflurane with a starting end-tidal isoflurane concentration of 1.3% (isoflurane group) or a concentration of 1% supplemented with an adjustable continuous infusion of guaifenesin-ketamine (IGK group) or romifidine-ketamine (IRK group). A predefined scoring system was used to assess anesthetic depth and to adjust anesthetic delivery. The need for rescue anesthetics and recovery quality were compared.


RESULTS
A mean ± SD end-tidal isoflurane concentration of 1.36 ± 0.16% was necessary to maintain a surgical plane of anesthesia in the isoflurane group. Mean infusion rates of 5.0 ± 1.3 μL/kg/min and 5.1 ± 0.8 μL/kg/min were necessary to maintain a surgical plane of anesthesia in the IRK and IGK groups, respectively. A lower need for ketamine as a rescue anesthetic was observed in the IGK group, compared with the isoflurane group. Higher blood pressure and lower heart rates were found at selected time points for the IRK group, compared with the IGK and isoflurane groups.


CONCLUSIONS
Both PIVA protocols were satisfactory to maintain smooth and stable surgical anesthesia in horses. The present study supports previous findings in which PIVA has isoflurane-sparing effects. Furthermore, PIVA did not impair recovery quality.
Department of Pathology, Diagnostic and Veterinary Clinic, Section of Surgery and Radiodiagnostic, Veterinary Teaching Hospital, University of Perugia, 06126, Perugia, Italy. sara.nannarone@unipg.it
Sara
S
Nannarone
Claudia
C
Spadavecchia
D000768:Anesthesia, General / Q000379:methods / Q000662:veterinary*; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D001794:Blood Pressure / Q000187:drug effects; D004562:Electrocardiography / Q000662:veterinary; D005260:Female; D006140:Guaifenesin / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000097:blood / Q000502:physiology* / Q000601:surgery; D007093:Imidazoles / Q000008:administration & dosage*; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage*; D007649:Ketamine / Q000008:administration & dosage*; D008297:Male
D007093:Imidazoles; D006140:Guaifenesin; D007649:Ketamine; C076257:romifidine; D007530:Isoflurane