Study objective: To measure plasma catecholamine levels and the cardiovascular response after administering epinephrine by the intraosseous (IO) route in an animal cardiac arrest model.
Model: Eighteen anesthetized swine (weight, 12 to 15 kg) subjected to five minutes of electrically induced ventricular fibrillation followed by 25 minutes of chest compression and ventilation.
Interventions: Animals were anesthetized with 30 mg/kg IM ketamine and 75 mg/kg IV a-chloralose, intubated, placed on a respirator, and surgically instrumented. Ventricular fibrillation was induced. After five minutes of cardiac arrest, mechanical chest compressions were initiated and continued until the end of the experiment. Animals received 0.01 mg/kg IO epinephrine (five) or 0.1 mg/kg IO epinephrine (five) at ten and 20 minutes. The eight controls did not receive epinephrine.
Measurements and main results: Plasma epinephrine levels increased from 1.0 to approximately 40 to 85 ng/mL with the initiation of CPR. Epinephrine (0.01 mg/kg) increased plasma epinephrine levels to 222 +/- 72 ng/mL at 12 minutes after arrest but did not increase diastolic or mean blood pressure. Epinephrine (0.1 mg/kg) increased plasma epinephrine levels to 1,103 +/- 157 ng/mL at 12 minutes after arrest and increased diastolic and mean arterial blood pressures.
Conclusion: IO epinephrine is rapidly transported to the central circulation but requires larger than currently recommended doses to produce a significant change in blood pressure.