Plasma catecholamine levels after intraosseous epinephrine administration in a cardiac arrest model.

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.