THE EFFECT OF INTRAVENOUS MAGNESIUM ADMINISTRATION ON AORTIC, RIGHT ATRIAL AND CORONARY PERFUSION PRESSURES DURING CPR IN SWINE

Objective: To determine the effect of magnesium administration on aort ic, right atrial and coronary perfusion pressure (CPP) during cardiopu lmonary resuscitation (CPR). Design: Twelve swine weighing 23.2 +/- 3. 1 kg were instrumented for CPP, aortic systolic (AOSP) and aortic dias tolic (AODP) pressures. Intervention: Ventricular fibrillation was ind uced and after 20 min of CPR the animals were allocated to receive epi nephrine 0.2 mg/kg, or epinephrine 0.2 mg/kg plus magnesium 0.14 g/kg. Epinephrine was repeated every 5 min. Arterial blood gases were deter mined during normal sinus rhythm and prior to drug administration. Res ults: Pressures were recorded and averaged over four consecutive 5-min intervals following initial drug administration. AOSP, AODP and CPP w ere compared using an analysis of covariance. AOSP was statistically l ower in the group receiving magnesium. There was a trend toward lower AODP and CPP in the group receiving magnesium as well. These statistic al differences and trends were absent after adjusting for pressures du ring normal sinus rhythm and serum bicarbonate prior to drug administr ation. Conclusions: In this model of prolonged cardiac arrest, the adm inistration of magnesium with epinephrine appeared to have a negative effect on aortic pressures during CPR. Further study is needed to dete rmine the confounding effect of serum bicarbonate on the response to e pinephrine and magnesium during CPR.