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Immediate survival among patients in cardiac arrest after three attempted direct current (DC) defibrillations for ventricular fibrillation (VF) or who are in asystole and receiving adequate cardiopulmonary resuscitation is less than 10%—the hospital discharge rate is less than 2%. Adrenaline is advocated to improve survival.
The recommended dose of adrenaline is 1 mg bolus administered intravenously repeated every three minutes as necessary. A prospective placebo controlled trial of “standard dose” adrenaline (0.01–0.02 mg/kg), however, has not been performed in patients with cardiac arrest. The effects of standard dose adrenaline have been analysed in a large retrospective study of 1360 patients with witnessed out-of-hospital VF.1 Some emergency medical staff were authorised to give standard doses of adrenaline during the observational period. Adrenaline was given to 35% of patients and was associated with a significantly greater rate of restoration of spontaneous circulation and hospital admission. However, there was no significant difference in hospital discharge rates between the two groups. Thus adrenaline and its dosage during cardiac arrest remain controversial.
High dose adrenaline
Administration of high dose adrenaline (0.1 or 0.2 mg/kg) compared with that of a standard dose in experimental animals after cardiac arrest causes an increase in aortic diastolic pressure, coronary perfusion pressure, resuscitation rates, and neurological outcome. However, the fibrillating heart rapidly consumes oxygen. High dose adrenaline may increase myocardial oxygen demand without increasing oxygen availability, and may cause contraction brand necrosis in the myocardium. In addition, ventricular arrhythmias and ventilation perfusion defects are associated with high dose adrenaline. Four large randomised studies have compared high dose and standard dose adrenaline in adults with cardiac arrest.2-5 A further study included a placebo group.6
The first study reported by Stiell et al in 19922 was performed in-hospital and out-of-hospital. High dose adrenaline (7 mg) was compared with a standard dose (1 mg), each administered at …