Plasma concentrations of epinephrine during CPR in the dog. STUDY OBJECTIVE: The purpose of this study was to evaluate whether the marked increase in the plasma concentrations of epinephrine during cardiopulmonary arrest and basic life support (BLS) could be due in part to decreased distribution and/or elimination. DESIGN AND INTERVENTIONS: Dogs were randomly assigned to undergo adrenalectomy or sham-operation. Some adrenalectomized animals received an epinephrine infusion. MEASUREMENTS AND MAIN RESULTS: In the seven sham-operated dogs, the plasma epinephrine concentrations increased markedly during BLS as expected. In the seven adrenalectomized dogs receiving a constant infusion of epinephrine, cardiopulmonary arrest and BLS induced a three to sixfold increase in plasma epinephrine concentrations, with an increase in the mean plasma epinephrine concentrations (calculated from the area under the curve) of 1.21 +/- 0.12 ng/mL (P less than .05). In the seven adrenalectomized dogs receiving a constant epinephrine infusion but not subjected to cardiopulmonary arrest, the plasma epinephrine concentrations remained stable. Finally, in the seven adrenalectomized dogs not receiving an epinephrine infusion, the mean plasma epinephrine concentrations during BLS (calculated from the area under the curve) increased only by 0.05 +/- 0.04 ng/mL, significantly less than in adrenalectomized dogs receiving an epinephrine infusion (P less than .01). CONCLUSION: The increase in plasma epinephrine concentrations during cardiopulmonary arrest and BLS is due in part to an altered disposition of epinephrine. 