Effects of Endotracheal Weight-Based Epinephrine on Pharmacokinetics and Survival in Swine With a Cardiac Arrest.

Abstract

Background: The aims of this study were to compare concentration maximum (Cmax), time to Cmax, area under the curve, mean concentration over 4 minutes, and frequency and time to return of spontaneous circulation (ROSC) by group.

Methods: This was a prospective, experimental study using swine. In total, 40 pigs (n = 8 per group) were assigned as follows: 0.1 mg/kg endotracheal (ET) tube, 1 mg intravenous (IV), 2 mg ET, Cardio Pulmonary Resuscitation (CPR) + defibrillation (CPR + defib), and CPR-Only. Pigs were placed in arrest for 2 minutes, CPR was then initiated for 2 minutes, and epinephrine was then administered and repeated every 4 minutes or until ROSC. Blood samples were collected over 4 minutes. Defibrillation was initiated at 3 minutes and continued every 2 minutes for 30 minutes or until ROSC. CPR + defib and CPR-Only Groups served as controls. The CPR + defib Group had defibrillations but did not receive epinephrine. The CPR-Only Group did not receive defibrillations or epinephrine.

Results and conclusions: The Cmax and area under the curve were significantly higher in the IV Group compared to the 0.1 mg/kg ET Group (P < .05). The time to Cmax was significantly longer in the 0.1 mg/kg Group than the 1 mg IV Group (P = .03). The mean concentration of the 1 mg IV Group was higher than the 0.1 mg/kg ET Group until 180 and 240 seconds. There was no significant difference between the groups relative to time to ROSC (P > .05). Return of spontaneous circulation frequencies were: 0.1 mg/kg ET Group (7 of 8); 1 mg IV Group (5 of 8); and 2 mg ET Group (1 of 8), and both CPR + defib and CPR-Only (0 out of 8). This study challenges the current guidelines relative to ET epinephrine administration. Based on our ROSC data, the 0.1 mg/kg dose of epinephrine by ET should be used as a first-line intervention.