The recovery of horses from inhalant anesthesia: a comparison of halothane and isoflurane.

OBJECTIVE Recovery is one of the more precarious phases of equine general anesthesia. The quality and rate of recovery of horses from halothane and isoflurane anesthesia were compared to determine differences in the characteristics of emergence from these commonly used inhalant anesthetics. EXPERIMENTAL DESIGN Prospective, randomized blinded clinical trial. SAMPLE POPULATION A total of 96 Thoroughbred and 3 Standardbred racehorses admitted for elective distal forelimb arthroscopy. METHODS All horses were premedicated with intravenous xylazine, induced with guaifenesin and ketamine, and maintained on a large animal circle system fitted with an out of the circle, agent specific vaporizer. Recoveries were managed by a blinded scorer with a standardized protocol. A 10 category scoring system was used to assess each horse's overall attitude, purposeful activity, muscle coordination, strength and balance from the time of arrival in recovery to standing. Times to extubation, sternal recumbency and standing were recorded. Median recovery scores and mean times to extubation, sternal and standing were compared using the Mann-Whitney U test and student's t test, respectively. RESULTS The median score for horses recovering from halothane was lower (20.0; range, 10 to 57) than that for horses recovering from isoflurane (27.5; range, 10 to 55). Horses in the two groups were extubated at similar mean times (halothane, 11.3 +/- 5.5 and isoflurane, 9.5 +/- 5.2 minutes) but horses recovering from isoflurane achieved sternal recumbency (halothane, 37.7 +/- 12.1 and isoflurane, 24.7 +/- 8.8 minutes) and stood (halothane, 40.6 +/- 12.9 and isoflurane, 27.6 +/- 9.6 minutes) sooner than those recovering from halothane. CONCLUSIONS The recovery of horses from isoflurane anesthesia was more rapid but less composed than that from halothane. CLINICAL RELEVANCE The quality of recovery following isoflurane was worse than after halothane anesthesia using the criteria chosen for this study. However, the range of recovery scores was similar for both groups and all horses recovered without significant injury.

[1]  W. Muir,et al.  Cardiorespiratory effects of sevoflurane, isoflurane, and halothane anesthesia in horses. , 1998, American journal of veterinary research.

[2]  D. Sessler,et al.  Mild Intraoperative Hypothermia Prolongs Postanesthetic Recovery , 1997, Anesthesiology.

[3]  J. Bailey.  Context-Sensitive Half-Times and Other Decrement Times of Inhaled Anesthetics , 1997, Anesthesia and analgesia.

[4]  U. Ruttimann,et al.  Comparison of Emergence and Recovery Characteristics of Sevoflurane, Desflurane, and Halothane in Pediatric Ambulatory Patients , 1996, Anesthesia and analgesia.

[5]  H. Kawanabe,et al.  Comparisons of sevoflurane, isoflurane, and halothane anesthesia in spontaneously breathing cats. , 1996, Veterinary surgery : VS.

[6]  D. Coursin,et al.  Assessment of sedation, analgesia, and neuromuscular blockade in the perioperative period. , 1996, International anesthesiology clinics.

[7]  M. Holmes,et al.  Confidential enquiry of perioperative equine fatalities (CEPEF-1): preliminary results. , 1995, Equine veterinary journal.

[8]  W. Muir,et al.  Blood gas values during intermittent positive pressure ventilation and spontaneous ventilation in 160 anesthetized horses positioned in lateral or dorsal recumbency. , 1995, Veterinary surgery : VS.

[9]  E. Faragher,et al.  Recovery after oral surgery with halothane, enflurane, isoflurane or propofol anaesthesia. , 1994, British journal of anaesthesia.

[10]  N. Willits,et al.  Recovery of horses from inhalation anesthesia. , 1993, American journal of veterinary research.

[11]  S. Nishimura,et al.  Alterations in pain threshold and psychomotor response associated with subanaesthetic concentrations of inhalation anaesthetics in humans. , 1993, British journal of anaesthesia.

[12]  P. Taylor,et al.  Factors influencing the outcome of equine anaesthesia: a review of 1,314 cases. , 1993, Equine veterinary journal.

[13]  W. Kwan,et al.  Recovery of cognitive functions after anaesthesia with desflurane or isoflurane and nitrous oxide. , 1992, British journal of anaesthesia.

[14]  S. Miller,et al.  Comparison of recoveries from halothane vs isoflurane anesthesia in horses. , 1992, Journal of the American Veterinary Medical Association.

[15]  E. Tassonyi,et al.  MAC-AWAKE OF ISOFLURANE, ENFLURANE AND HALOTHANE EVALUATED BY SLOW AND FAST ALVEOLAR WASHOUT , 1992 .

[16]  D. Marshall,et al.  Equine post-anesthetic lameness. A retrospective study. , 1990, Veterinary surgery : VS.

[17]  D. Chernik,et al.  Validity and Reliability of the Observer's: Assessment of Alertness/Sedation Scale Study with Intravenous Midazolam , 1990, Journal of clinical psychopharmacology.

[18]  Y. Moens.  Arterial-alveolar carbon dioxide tension difference and alveolar dead space in halothane anaesthetised horses. , 1989, Equine veterinary journal.

[19]  G. Hedenstierna,et al.  Ventilation-perfusion relationships in the anaesthetised horse. , 1989, Equine veterinary journal.

[20]  J. G. Adams,et al.  A retrospective survey of anaesthesia in horses with colic. , 1989, Equine veterinary journal. Supplement.

[21]  E. Eger,et al.  Rates of Awakening from Anesthesia with I‐653, Halothane, Isoflurane, and Sevoflurane: A Test of the Effect of Anesthetic Concentration and Duration in Rats , 1987, Anesthesia and analgesia.

[22]  H. Erb,et al.  Isoflurane anesthesia for equine colic surgery. Comparison with halothane anesthesia. , 1987, Veterinary surgery : VS.

[23]  C. Seymour,et al.  Clinical experiences with isoflurane in dogs and horses , 1986, Veterinary Record.

[24]  U. Pandit,et al.  Induction and recovery characteristics of isoflurane and halothane anaesthesia for short outpatient operations in children , 1985, Anaesthesia.

[25]  P. Taylor,et al.  ISOFLURANE IN THE HORSE , 1984 .

[26]  E. Eger,et al.  Determination and applications of MAC. , 1980, Anesthesiology.

[27]  E. Steffey,et al.  Comparison of circulatory and respiratory effects of isoflurane and halothane anesthesia in horses. , 1980, American journal of veterinary research.

[28]  H. Garner,et al.  Recovery from anaesthesia in ponies: a comparative study of the effects of isoflurane, enflurane, methoxyflurane and halothane. , 1978, Equine veterinary journal.

[29]  E. Eger,et al.  Enflurane, halothane, and isoflurane potency in horses. , 1977, American journal of veterinary research.

[30]  E. Eger,et al.  The effects of ventilation and anesthetic solubility on recovery from anesthesia: an in vivo and analog analysis before and after equilibrium. , 1969, Anesthesiology.