Endotracheal epinephrine: a call for larger doses

Area of Science:

• Emergency Medicine
• Pharmacology
• Critical Care

Background:

• Endotracheal epinephrine is recommended when intravenous access is unavailable during cardiopulmonary resuscitation.
• The standard intravenous dose of epinephrine may be too low for endotracheal administration, potentially causing detrimental decreases in blood pressure.
• The mechanism for this decrease is thought to be unopposed beta-adrenergic receptor stimulation.

Purpose of the Study:

• To determine the optimal dose of endotracheal epinephrine for increasing arterial blood pressure (BP).
• To compare the effects of increasing doses of endotracheal epinephrine in a controlled laboratory setting.

Main Methods:

• A prospective, randomized laboratory study was conducted on five anesthetized dogs.
• Increasing doses of epinephrine (0.02, 0.035, 0.1, 0.2, and 0.3 mg/kg) were administered via endotracheal tube, with normal saline as a control.
• Arterial blood pressure, heart rate, and blood gases were monitored for 60 minutes post-administration.

Main Results:

• Only the highest dose tested (0.3 mg/kg) resulted in a significant increase in arterial blood pressure.
• This increase was observed within 2 minutes and lasted for 10 minutes.
• A decrease in blood pressure was avoided only at a dose 10-fold higher than the currently recommended endotracheal dose.

Conclusions:

• The optimal dose of endotracheal epinephrine for increasing blood pressure is significantly higher than currently recommended.
• Larger doses of endotracheal epinephrine may be effective in raising blood pressure during cardiac arrest.
• Further clinical studies are warranted to evaluate higher doses of endotracheal epinephrine as a potential first-line therapy.