title: Effects of intravenous fentanyl administration on end-tidal sevoflurane concentrations in thoroughbred racehorses undergoing orthopedic surgery.
abstract: To evaluate the effects of IV fentanyl administration on the end-tidal sevoflurane concentration (ET(SEVO)) in thoroughbred racehorses, the ET(SEVO) required for internal fixation of longitudinal fractures was compared between horses anesthetized with sevoflurane-fentanyl (Group SF; n=9) and those anesthetized with sevoflurane alone (Group S; n=9). The loading dose of fentanyl (5.0 µg/kg) was administered over 15 min followed by a maintenance dose of fentanyl (0.1 µg/kg/min) throughout the operation in Group SF. The mean ET(SEVO) during the operation in Group SF (2.6 ± 0.2%) was significantly lower than in Group S (3.0 ± 0.3%). The plasma fentanyl concentrations (6.12 ± 0.88 to 7.78 ± 1.12 ng/ml) in 7 out of 9 horses in Group SF were stable and did not change significantly throughout the operation. The mean dobutamine infusion rate required for maintaining a mean arterial blood pressure between 60 and 80 mmHg during the operation in Group SF (0.56 ± 0.30 µg/kg/min) was significantly lower than in Group S (0.90 ± 0.16 µg/kg/min). The qualities of the recoveries were clinically acceptable, and serious complications were not observed in either group. In conclusion, continuous IV fentanyl administration reduced the sevoflurane requirement by 13% in thoroughbred racehorses undergoing orthopedic surgery; however, fentanyl was considered to be less effective in horses compared with other species.
authors.affiliation: Racehorse Clinic, Ritto Training Center, Japan Racing Association (JRA), Ritto-shi, Shiga, Japan. Minoru_Ota@jra.go.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Ohta
authors.forename: Ai
authors.initials: A
authors.lastname: Wakuno
authors.forename: Jun
authors.initials: J
authors.lastname: Okada
authors.forename: Kazumichi
authors.initials: K
authors.lastname: Kodaira
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Nagata
authors.forename: Motoki
authors.initials: M
authors.lastname: Ito
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Oku
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000627:therapeutic use; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005283:Fentanyl / Q000008:administration & dosage / Q000627:therapeutic use*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary; D006339:Heart Rate / Q000187:drug effects; D006734:Horse Diseases / Q000601:surgery*; D006736:Horses; D007262:Infusions, Intravenous; D016268:Internal Fixators / Q000662:veterinary; D008738:Methyl Ethers / Q000097:blood*; D019637:Orthopedic Procedures / Q000379:methods / Q000662:veterinary*; D000077149:Sevoflurane; D013990:Tidal Volume / Q000187:drug effects
chemical_list: D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D000077149:Sevoflurane; D005283:Fentanyl