Effects of Intravenous Fentanyl Administration on End-Tidal Sevoflurane Concentrations in Thoroughbred Racehorses undergoing Orthopedic Surgery

Abstract

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 sevofluranefentanyl (Group SF; n=9) and those anesthetized with sevoflurane alone (Group S; n=9). The loading dose of fentanyl (5.0 g/kg) was administered over 15 min followed by a maintenance dose of fentanyl (0.1 g/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 g/kg/min) was significantly lower than in Group S (0.90  0.16 g/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.

Cardiopulmonary effects of an infusion of remifentanil or morphine in horses anesthetized with isoflurane and dexmedetomidine

“…; Ohta et al. ). Dexmedetomidine, however, has been reported to have a significant impact on hemodynamic variables when administered as an infusion to isoflurane‐anesthetized ponies (Marcilla et al.…”

Prolonged anesthesia using sevoflurane, remifentanil and dexmedetomidine in a horse

“…Fentanyl and remifentanil have been used in horses for analgesia and PIVA as part of a balanced anesthesia technique, but their long‐term use has not been reported (Ohta et al. ; Benmansour et al. ).…”

Anesthetic management with sevoflurane combined with alfaxalone-medetomidine constant rate infusion in a Thoroughbred racehorse undergoing a long-time orthopedic surgery

“… . We previously reported that the mean ET SEVO concentrations required for arthroscopic surgery and internal fixation were 2.8 ± 0.1% [ 20 ] and 3.0 ± 0.3% [ 19 ], respectively, when anesthesia was maintained with sevoflurane alone. We have also reported that medetomidine CRI reduced the mean ET SEVO concentrations required for arthroscopic surgery by approximately 10% [ 20 ].…”

“…MAP was maintained above 70 mmHg throughout anesthesia. We previously reported that the mean dobutamine infusion rate required for keeping MAP between 60 and 80 mmHg was 0.90 ± 0.16 µ g/kg/hr when anesthesia was maintained with sevoflurane alone for internal fixation [ 19 ]. The dobutamine infusion rate required for keeping MAP within the target value was much lower in the current case ( Fig.…”