Gastric Myoelectric and Motor Activity in Dogs After Isoflurane Anesthesia

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Abstract
To characterize the effects of isoflurane on gastric motility, gastric electrical and contractile activities were assessed in six healthy adult dogs before and after recovery from anesthesia. Baseline recordings (fasting and fed state) were obtained in unanesthetized dogs 8 days after implantation of serosal electrodes and strain‐gauge force transducers. After an overnight fast, dogs were anesthetized with 1.3 minimum alveolar concentration (MAC) isoflurane for 4.5 hours (approximately 6 MAC hours). No other anesthetic or sedative drugs were administered. During anesthesia, ventilation was mechanically controlled to maintain arterial carbon dioxide tension at 36 ± 4 mm Hg. Gastric electrical and contractile activities (fasting and fed state) were recorded again 18 hours after recovery from isoflurane anesthesia. Recordings were analyzed to determine gastric slow‐wave frequency, presence of slow‐wave dysrhythmias, slow‐wave propagation velocity, coupling of contractions to slow waves, a motility index based on relative contractile amplitudes, and onset and duration of contractions after a standardized meal. The only variable that was significantly decreased 18 hours after 6 MAC hours of isoflurane anesthesia was the gastric motility index during fasting‐state phase III. This decrease was not apparent in the fed‐state test periods. Our results suggest that, with the exception of gastric motility index during fasting‐state phase III, variables for gastric electrical and contractile activities in dogs are unaffected by isoflurane 18 hours after anesthesia.