Minimum Alveolar Concentration for Blunting Adrenergic Responses (MAC-BAR) of Sevoflurane in Dogs

Abstract

ABSTRACT. It is well known that heart rate or arterial blood pressure may increase in response to surgical stimulation despite the absence of a purposeful movement. However, there is limited information regarding anesthetic requirement for blunting adrenergic response in dogs. This study was designed to compare the minimum alveolar concentrations of sevoflurane required to prevent autonomic response (MAC-BAR) and purposeful movement (MAC) in dogs. Sevoflurane MAC-BAR and MAC were determined in 5 beagle dogs by judging dogs' response to a noxious electrical stimulus applied to the gingiva. The sevoflurane MAC-BAR was significantly higher than MAC (3.33 ± 0.48 vs 2.10 ± 0.28%, P=0.005). These results suggested that autonomic responses occurred at sevoflurane anesthetic concentrations at which purposeful movements were absent.

Sparing Effect of Robenacoxib on the Minimum Alveolar Concentration for Blunting Adrenergic Response (MAC-BAR) of Sevoflurane in Dogs

“…In the present study, the sevoflurane MAC-BAR after administration of saline for the dogs was 3.44 ± 0.53% and is similar to the MAC-BAR value for middle aged (9 to 11 years old) intact female dogs (3.33%) [25]. On the other hand, the sevoflurane MAC-BAR values for intact male dogs reported by Love et al [16] and Seddighi et al [22] (2.77% and 2.50%, respectively) are lower than that in the present study.…”

“…MAC-BAR determination began, after the dogs were allowed to equilibrate for 60 min at EtSEV 3.0%. The MAC-BAR of sevoflurane was determined by judging the dogs’ response to a noxious electrical stimulus (50 V, 50 Hz and 10 msec) [25] applied to their right upper gingival. The electrical stimulus was applied for 10 sec using an electrical stimulator (SEN3301, Nihon Koden Co., Tokyo, Japan).…”

“…In the present study, heart rate was within normal values for dogs during anesthesia, however, MABP was close to clinically lower limit (60 mmHg) in both groups during the MAC-BAR determination. The end-tidal concentration of sevoflurane that prevents an autonomic response to a noxious stimulation (i.e., MAC-BAR) is higher than that prevents movements (i.e., MAC), and it was reported that the ratio of MAC-BAR/MAC was 1.61 MAC for sevoflurane in dogs [25]. Because sevoflurane produces the cardiovascular depression in a dose-dependent manner, the concentration required for blocking the autonomic response can induce considerable cardiovascular depression in dogs.…”

Interaction between maropitant and carprofen on sparing of the minimum alveolar concentration for blunting adrenergic response (MAC-BAR) of sevoflurane in dogs

“…The MAC-BAR determination began after the dogs were allowed to equilibrate for 60 min at ETSEV 3.0%. The MAC-BAR of sevoflurane was determined according to the previous studies [32, 37]. Briefly, the MAC-BAR of sevoflurane was determined by judging the dogs’ response to a noxious electrical stimulus (50 V, 50 Hz, 10 msec) applied to their right upper gingival for 10 sec using an electrical stimulator (SEN3301, Nihon Koden Co., Tokyo, Japan).…”

The effect of remifentanil on the minimum alveolar concentration (MAC) and MAC derivatives of sevoflurane in dogs

“…When the dog showed a positive response before the cycle was completed, the electrical stimulation was stopped. A positive response to the electrical stimulation for determination of the SEV MAC-BAR was defined as the increase in the MAP or HR >15% above the value recorded at 1 min prior to applying the electrical stimulation [ 23 ]. A positive response to the electrical stimulation to determine the SEV MAC was defined as gross purposeful movements including head lifting and repeated limb movement, with the exception of the forelimb that underwent electrical stimulation.…”