The use of undiluted amiodarone in the management of out-of-hospital cardiac arrest.

INTRODUCTION: The Resuscitation 2000 Guidelines recommends amiodarone as the antiarrhythmic drug of choice in treatment of resistant ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). Amiodarone has been associated with side-effects and difficulty of administration, due to recommended dilution, rendering it suboptimal for out-of-hospital cardiac arrest (CA) management. In the present study we report experiences and side-effects of the use of undiluted amiodarone in CA management in Helsinki Emergency Medical Service (EMS) during a 2-year period.

METHODS: On October 1, the Resuscitation 2000 Guidelines were put into practice in Helsinki EMS. Thus, in the cardiac arrest treatment protocol, after three ineffective shocks and 1 mg of adrenaline (epinephrine), a bolus of 300 mg of undiluted amiodarone (Cordarone 50 mg ml(-1), Sanofi-Synthelabo, Helsinki, Finland) was administered into a vein located as centrally as possible. The Helsinki EMS performs systematic data collection according to the Utstein Guidelines. The blood pressure levels, heart rates and the need for vasopressors, of the patients with sustained return of spontaneous circulation (ROSC), were collected from the ambulance charts.

RESULTS: During October 1, 2000 and September 30, 2002, 712 patients were considered for resuscitation and 566 were resuscitated. The initial rhythms were as follows: 32% had VF/VT, 36% had asystole and 32% had pulseless electrical activity (PEA). Of the 180 patients with VF/VT, 75 (42%) received undiluted amiodarone in addition to other resuscitative measures. Of the patients with asystole or PEA, 12 (6%) and 18 (10%), respectively, received amiodarone. The blood pressure levels and the need vasopressors after ROSC and during transportation to the hospital were similar among the patients who received and those who did not receive amiodarone.

CONCLUSIONS: The present study suggests that amiodarone can be administered undiluted without unmanageable haemodynamical side-effects in the treatment of out-of-hospital cardiac arrest. This is likely to save time and simplifies the treatment protocol in the prehospital setting.