Objective: To determine whether standard or increased doses of atropine improve the return of spontaneous circulation (ROSC) rate in a canine model of pulseless electrical activity (PEA).
Methods: A prospective, controlled, blinded laboratory investigation was performed using an asphyxial canine cardiac arrest model. After the production of asphyxial PEA, 75 dogs remained in untreated PEA for 10 minutes and then were randomized to receive placebo (group 1) or one of four doses of atropine (group 2, 0.04 mg/kg; group 3, 0.1 mg/kg; group 4, 0.2 mg/kg; group 5, 0.4 mg/kg). All the animals received mechanical external CPR and epinephrine (0.02 mg/kg every 3 minutes) throughout resuscitation.
Results: The ROSC rates were not significantly different between the groups (group 1, 73%; group 2, 67%; group 3. 40%; group 4, 47%; group 5, 27%; p = 0.06). The heart rates and hemodynamics during resuscitation were not significantly different between the groups.
Conclusion: In this canine model of asphyxial PEA cardiac arrest, standard-dose atropine did not improve ROSC rates, compared with placebo. Increasing doses of atropine tended to decrease ROSC rates, compared with placebo and standard-dose atropine.