Cardiopulmonary effects of three concentrations of isoflurane with or without mechanical ventilation and supramaximal noxious stimulation in New Zealand white rabbits

Abstract

In rabbits, isoflurane-induced dose-dependent cardiopulmonary depression was attributable to vasodilation and negative inotropy. At an isoflurane concentration of 4.15% with mechanical ventilation, cardiovascular depression was severe; use of unnecessarily high isoflurane concentrations in this species should be avoided.

Comparison of Doppler, oscillometric, auricular and carotid arterial blood pressure measurements in isoflurane anesthetized New Zealand white rabbits

“…In conjunction with another study (Barter & Epstein ) each rabbit was anesthetized on two occasions, both with three concentrations of isoflurane and once each with controlled or spontaneous ventilation. On each occasion following instrumentation, the end‐tidal isoflurane concentration (F e ′Iso) was randomly set at 1.0, 1.5 or 2.0 times the previously published MAC of isoflurane in rabbits (2.07%; Imai et al.…”

Cardiovascular effects of equipotent doses of isoflurane alone and isoflurane plus fentanyl in New Zealand White rabbits (Oryctolagus cuniculus)

“…6,21 In addition, hypercapnia increases sympathetic nervous system tone and can alter cardiovascular variables. 4 This effect is likely attributable in part to the effect of increasing PaCO 2 with increasing isoflurane concentrations in spontaneously breathing animals and the negative impact of positive intrathoracic pressures on venous return in mechanically ventilated animals. 4 This effect is likely attributable in part to the effect of increasing PaCO 2 with increasing isoflurane concentrations in spontaneously breathing animals and the negative impact of positive intrathoracic pressures on venous return in mechanically ventilated animals.…”

“…In the first experiment, MAC was determined in duplicate for each isoflurane-anesthetized rabbit prior to administration of fentanyl (ie, baseline) and at 3 targeted plasma fentanyl concentrations (4,8, and 16 ng/mL, determined on the basis of results of a previous study 8 ). In the first experiment, MAC was determined in duplicate for each isoflurane-anesthetized rabbit prior to administration of fentanyl (ie, baseline) and at 3 targeted plasma fentanyl concentrations (4,8, and 16 ng/mL, determined on the basis of results of a previous study 8 ).…”

“…This was performed once at baseline and twice for each targeted plasma concentration (4,8, and 16 ng/mL): the first sample was obtained 15 minutes after starting the fentanyl infusion, and the second was collected at the time of the second MAC determination for each targeted plasma concentration. The end-tidal isoflurane concentration was increased by 10% if movement occurred or decreased by 10% if movement did not occur, and another 15-minute period of stable end-tidal isoflurane concentration was allowed prior to reapplication of the stimulus.…”

Effects of fentanyl on isoflurane minimum alveolar concentration in New Zealand White rabbits (Oryctolagus cuniculus)

“…In addition to providing analgesia, opioid-inhalation anesthetic combinations have been associated with beneficial cardiovascular effects, which are thought to be related to opioidinduced MAC reduction. 3 1 Fentanyl is, however, a potent respiratory depressant.…”