EFFECTS OF VAGAL TONE ON RESUSCITATION FROM EXPERIMENTAL ELECTROMECHANICAL DISSOCIATION

Study objective: To determine if complete loss of vagal tone improves the return of spontaneous circulation rate in a canine model of electr omechanical dissociation cardiac arrest. Design: Prospective, controll ed laboratory investigation using an asphyxial canine cardiac arrest m odel randomized to receive bilateral cervical vagotomy or no vagotomy. Interventions: After the production of asphyxial electromechanical di ssociation arrest, 16 mongrel dogs remained in untreated electromechan ical dissociation for ten minutes and then were randomized to receive bilateral cervical vagotomy or no vagotomy. All animals received stand ard external CPR and epinephrine (0.02 mg/kg every five minutes) throu ghout resuscitation. Measurements and main results: Return of spontane ous circulation was achieved in 13% (one of eight) of no vagotomy and 75% (six of eight) of vagotomy animals (P = .02). Survival to one hour was achieved in 100% (one of one) of no vagotomy and 83% (five of six ) of vagotomy animals (P = NS). The hemodynamic and arterial blood gas values at five, ten, and 15 minutes into resuscitation were not signi ficantly different between groups. Conclusion: In this canine model of asphyxial electromechanical dissociation cardiac arrest, surgical vag otomy and complete loss of vagal tone improved the rate of return of s pontaneous circulation.