Effect of epinephrine on end-tidal carbon dioxide pressure during prehospital cardiopulmonary resuscitation.

This prospective study was designed to quantify the effect of epinephrine on end-tidal PCO2 (PetCO2) during prehospital cardiopulmonary resuscitation (CPR) in humans. It included 20 patients (age range, 26 to 90 years) who presented in ventricular asystole on arrival of the prehospital medical team. Protocol began 5 minutes after tracheal intubation and during chest compressions. Mechanical ventilation was applied at constant rate and tidal volume. PetCO2 was measured before and 3 minutes after peripheral intravenous (IV) injection of 2 mg epinephrine. No other resuscitative drugs were administered during the study period. Mean PetCO2 decreased from 16.7 +/- 9.3 mm Hg before epinephrine to 12.6 +/- 7.1 mm Hg after epinephrine. The mean change in PetCO2 was 4.15 +/- 3.5 mm Hg (P < .0001). Four patients exhibited return of spontaneous circulation (ROSC). The decrease in PetCO2 was similar between the patients who exhibited ROSC and those who did not. There was a significant relationship between the epinephrine-induced change in PetCO2 and the PetCO2 value before epinephrine injection (r = .760; P < .0001). This study demonstrates a variable decrease in PetCO2 after IV epinephrine injection during CPR. Isolated PetCO2 readings may be misleading in assessing CPR efficacy or predicting outcome, and continuous measurement is recommended.