Objective: Amiodarone has been shown to be superior to both placebo and lidocaine in improving survival to hospital admission for victims of out-of-hospital refractory ventricular fibrillation. Concern had been expressed about the known vasodilatatory effects of amiodarone if given without precedent vasoconstrictive medications. The haemodynamic effects of intravenous amiodarone administered during ongoing CPR have not been systemically investigated. Our intention was to verify if amiodarone alone produced significantly lower resuscitation haemodynamics than did either adrenaline (epinephrine) alone or the combination of amiodarone and adrenaline.
Design: Prospective, randomized, comparative study.
Setting: Research laboratory of a medical school.
Subjects: Thirty mongrel dogs.
Interventions: After 8 min of untreated VF, defibrillation was attempted once at 3 J/kg and external chest compressions and ventilation started. Those animals resistant to the defibrillation attempt were randomized, ten to an adrenaline (0.02 mg/kg) group, ten to an amiodarone (5 mg/kg) group, and ten to a group receiving a combination of both drugs.
Measurements and main results: Aortic systolic and diastolic, and coronary perfusion pressures were all significantly lower in the group receiving amiodarone alone than in the other two groups. Amiodarone combined with adrenaline produced pressures during CPR similar to adrenaline alone.
Conclusion: Amiodarone can be safely administered simultaneously in combination with adrenaline and such a combination results in similar haemodynamic support as adrenaline alone. Amiodarone administered alone produces significantly lower coronary perfusion pressure than when combined with adrenaline.