Determination of minimum alveolar concentration and cardiovascular effects of desflurane in positive-pressure ventilated sheep

• Published in: American journal of veterinary research Vol. 79; no. 7; pp. 727 - 732
• Main Authors: Columbano, Nicolò, Duffee, Lauren R, Melosu, Valentino, Scanu, Antonio, Dore, Simone, Sotgiu, Giovanni, Driessen, Bernd, Careddu, Giovanni M
• Format: Journal Article
• Language: English
• Published: United States 01-07-2018
• Subjects: Anesthesia; Anesthetics, Inhalation - pharmacology; Animals; Blood Pressure - drug effects; Body Temperature; Desflurane; Female; Heart Rate - drug effects; Isoflurane - administration & dosage; Isoflurane - analogs & derivatives; Positive-Pressure Respiration - veterinary; Sheep
• ISSN: 0002-9645; 1943-5681
• DOI: 10.2460/ajvr.79.7.727

OBJECTIVE To determine the minimum alveolar concentration of desflurane (MAC
) and effects on cardiovascular variables in positive-pressure ventilated sheep. ANIMALS 13 adult female sheep. PROCEDURES Anesthesia was induced with desflurane. After a 30-minute equilibration at an end-tidal concentration of desflurane (et
) of 10.5%, an electrical stimulus (5 Hz/ms and 50 mA) was applied for 1 minute or until gross purposeful movement occurred. The et
was then changed by 0.5% (modified up-down method), depending on whether a positive motor response had been elicited, and stimulation was repeated. The MAC
was the et
midway between a positive and negative response. After MAC
was determined, et
was increased to 1.3 and 1.6 MAC
. Animals were allowed to equilibrate for 15 minutes, and cardiovascular, blood gas, acid-base, and hematologic variables were measured. Times to induction of anesthesia, extubation, attainment of sternal position, and standing and duration of anesthesia were recorded. RESULTS Mean ± SD MAC
was 9.81 ± 0.79%. Times to intubation, extubation, and standing were 4.81 ± 2.21 minutes, 14.09 ± 4.05 minutes, and 32.4 ± 12.5 minutes, respectively. Duration of anesthesia was 226 ± 22 minutes. Heart rate increased significantly at induction of anesthesia but otherwise remained at preanesthetic rates. Arterial blood pressures progressively decreased with increasing et
; pressures increased slightly only in response to noxious stimulation. CONCLUSIONS AND CLINICAL RELEVANCE The MAC
determined here compared favorably with that determined for other sheep populations and indicated similar anesthetic potency as in other species. Desflurane caused dose-dependent arterial hypotension, which indicated the need for careful blood pressure monitoring.