Endotracheal versus intravenous epinephrine and atropine in out-of-hospital "primary" and postcountershock asystole

Study Objective: Pulmonary blood flow during cardiac arrest and cardiopulmo nary resuscitation (CPR) is <20% of normal, and transalveolar drug absorpti on is likely to be minimal. Animal and clinical CPR studies have not addres sed the use of endotracheal (ET) epinephrine in doses currently recommended for adults (twice the intravenous dose). The purpose of this study was to compare the effects of ET and intravenous drugs on cardiac rhythm in the pr ehospital setting. Design: A 3-yr (1995-1997) retrospective review of all cardiac arrests tran sported to a single, municipal teaching institution was performed. Patients: Patients >18 yrs in atraumatic cardiac arrest whose first documen ted field rhythm was asystole with time-to-definitive care of less than or equal to 10 mins (primary asystole) and patients found in ventricular fibri llation who developed postcountershock asystole (secondary asystole) were i ncluded. Patients were grouped according to route of drug administration (i v, ET, or no drug therapy) as well as rhythm (primary or secondary asystole ). A positive response to drug therapy was defined as any subsequent rhythm other than asystole during continued prehospital resuscitation. Measurements and Main Results.. A total of 136 patients met inclusion crite ria. The following groups were defined: group 1, primary asystole/iv drugs (n = 39); group 2, postcountershock asystole/iv drugs (n = 39); group 3, pr imary asystole/ET drugs (n = 25); group 4, postcountershock asystole/ET dru gs (n = 18); and group 5, primary or secondary asystole/no drug therapy (n 15). Significant differences were not observed between groups with respect to age, gender, witnessed arrest, frequency of bystander CPR, or time-to-de finitive care. The positive rhythm response rate was significantly greater in group 1 (64%) and group 2 (69%) (both p < .01) than in Group 3 (12%) or group 4 (11%). The response rate in the control group was 20% and not signi ficantly different from either ET group. The intravenous groups also had a significantly greater rate of return of spontaneous circulation (17%) when compared with the ET groups (0%) (p = .005). Conclusion: We conclude that the currently recommended doses of epinephrine and atropine administered endotracheally are rarely effective in the setti ng of cardiac arrest and CPR.