Effect of pentobarbital anesthesia on vulnerability to ventricular fibrillation

Abstract

Ventricular fibrillation threshold (VFT), frequently determined in dogs during pentobarbital sodium anesthesia, usually is replaced by a single repetitive extrasystole threshold (SRET) or a multiple repetitive extrasystole threshold (MRET) determination in conscious animals and in the human being. In the present study SRET, MRET, and VFT were determined initially in 39 pentobarbital sodium-anesthetized dogs. One week later these three thresholds were redetermined during anesthesia in 13 of the 39 dogs (control group). In the remaining 26 dogs (experimental group), thresholds were redetermined while the dogs were conscious. Significant changes in threshold values occurred only in the experimental group for VFT (P < 0.001) and MRET (P < 0.02). The square of the linear correlation coefficient showed conscious state MRET to be a good predictor of conscious state VFT (R2 = 0.90). Conscious state SRET and anesthetized state VFT showed less predictiveness for the conscious VFT (R2 = 0.72 and 0.51, respectively). These data indicate that MRET may be preferable to SRET as an index of VFT. The SRET, MRET, and VFT determined during pentobarbital anesthesia may not accurately reflect the value of these parameters in the conscious animal.

Pentobarbital versus medetomidine-ketamine-fentanyl anaesthesia: effects on haemodynamics and the incidence of ischaemia-induced ventricular fibrillation in swine

“…Like pentobarbital, both ketamine and fentanyl are known to possess antiarrhythmic effects (Hoffmeister et al 1958, Laforet et al 1958, Olichney & Modell 1958, Dawson et al 1980, Thurmon & Tranquilli 1986, Hunt & Ross 1988, Smith et al 1997. However, in the present study, swine anaesthetized with medetomidineketamine-fentanyl showed a substantially higher incidence of ischaemia-induced ventricular brillation than swine anaesthetized with pentobarbital.…”

“…This agent possesses a cardiodepressive effect (Priano et al 1969, Sawyer et al 1971, Bailie et al 1979, Namba et al 1994, with increased re ex pressoreceptor activity (Manders & Vatner 1976), and an antiarrhythmic effect (Hoffmeister et al 1958, Laforet et al 1958, Olichney & Modell 1958, Dawson et al 1980, Hunt & Ross 1988. Because these effects are dosedependent (Nattel et al 1990, Namba et al 1994, the smallest dose to achieve general anaesthesia is usually chosen.…”

Influence of Anesthetics on the Incidence of Reperfusion-Induced Arrhythmias and Sudden Death in Rats

“…It is also a membrane depressant on myocytes and reduces the responsiveness of these cells to sympathetic stimulation, thus having some kind of antiarrhythmic effect(12). Indeed, Siegmund et al(6) demonstrated that during pentobarbitone anaesthesia, compared to conscious animals, a significantly lower number of animals developed irreversible ventricular fibrillation during the first twenty minutes of myocardial infarction.Dawson et al(13) have shown that pentobarbitone affects the ventricular fibrillation threshold in dogs thus influencing the vulnerability of the myocardium to ventricular fibrillation.…”

Canine Model of Contrast Medium Induced Fibrillation

“…DAWSON et coIl. (3) have shown that pentobarbital anesthesia increases the threshold for electrically induced VF. We therefore believe that pentobarbital anesthesia decreases the vulnerability for CM induced VF, thus our canine model probably overestimates the contact time required for CM induced VF in the awake animal.…”