Abstract Body: Background
Current guidelines recommend epinephrine administration via intravenous (IV), intraosseous (IO), or endotracheal (ET) route; however, establishing IV/IO/ET access can take several minutes and may require proficient skills and/or specific equipment. Alternatively, intramuscular (IM) epinephrine could be administered immediately. At present, there is limited data on the use of IM epinephrine in pediatric resuscitation. We aimed to compare IM with IV epinephrine in a pediatric porcine model of asphyxia-induced cardiac arrest. We hypothesized that in a pediatric animal model of cardiac arrest, IM epinephrine would not be advantageous to IV epinephrine.

Methods
Twenty pediatric piglets (5–10 days old) were anesthetized and randomized to IM (0.3mg) or IV (0.02mg/kg/dose) epinephrine with bradycardic or asystolic cardiac arrest. IM-randomized piglets received one dose of epinephrine intramuscularly during positive pressure ventilation (PPV), prior to the commencement of chest compressions (CCs). Thereafter, they received subsequent doses of IV epinephrine every 3 minutes unless return of spontaneous circulation (ROSC). IV-randomized piglets received their first dose of epinephrine intravenously 2 minutes after the start of PPV. Subsequent IV doses of were given every 3 minutes until ROSC. Heart rate, arterial blood pressure, carotid blood flow, cardiac function, and cerebral oxygenation were continuously recorded throughout the experiment.

Results
Rates of ROSC were not different for IV compared to IM epinephrine in bradycardic piglets 3/5(60%) vs 3/5(60%), respectively (p=1.000). In asystolic piglets the rate of ROSC was not significantly different between IV and IM epinephrine groups, 1/5(20%) vs 2/5(40%), respectively (p=1.000). Median (IQR) time to ROSC with IV compared to IM epinephrine in bradycardic piglets was 240 (175-351)sec vs 115 (105-640)sec, respectively (p=0.513), and in asystolic piglets was 180sec vs 205 (180-230)sec, respectively (no p-value or IQR for IV asystolic group due to n=1 achieving ROSC).

Conclusions
In a pediatric piglet model of bradycardic and asystolic cardiac arrest, administration of IM epinephrine resulted in similar resuscitative outcomes to IV epinephrine. Although immediate IM epinephrine injection may provide a first-line treatment option until subsequent IV/IO access is established, large, randomized trials are needed to confirm our finding before it can be used during pediatric resuscitation.