Epinephrine application via a conventional endotracheal airway and via the Combitube™ in esophageal position in an animal model

Background

Early administration of epinephrine plays an essential role in the management of cardiac arrest patients. A new emergency airway, the Esophageal Tracheal Combitube™, provides rapid airway management when endotracheal intubation is not possible. The aim of our study was to compare plasma concentrations and the cardiovascular effects of epinephrine after application via a conventional endotracheal airway and via the esophageal lumen of the Combitube™.

Methods

Fourteen juvenile swine were randomly assigned to two subgroups: group A received an endotracheal tube, group B a Combitube™ in esophageal position. In part I of the study, epinephrine (group A, 0.05 mg/kg; group B, 0.5 mg/kg) was administered via the respective tube during spontaneous beating of the heart. In part II, 3 min after induction of ventricular fibrillation, CPR was started and 5 min later epinephrine (group A, 0.1 mg/kg; group B, 1.0 mg/kg) was administered. Plasma epinephrine levels were measured 1, 2, 3, 5, 7, 10, 15 and 30 min after application. Systolic arterial pressure and cardiac output in part I, and ETCO₂ and coronary perfusion pressure in part II were recorded.

Results

In part I increased levels of plasma epinephrine and systolic arterial pressure were maintained significantly longer in group B when compared to group A. In part II, no significant differences between the groups were found with regard to plasma epinephrine levels and hemodynamic parameters.

Conclusion

Epinephrine applied via the esophageal lumen of the Combitube™ in a 10-fold higher dosage than recommended for endotracheal application has similar effects on plasma epinephrine levels and hemodynamic parameters compared to endotracheal administration.

The prolonged intensive care support delivered also to patients with apparent poor prognosis in the first days allows to partially overcome the frequent criticism that early withdrawal of treatment results in a self-fulfilling prophesy of poor outcome. In fact, at day 7 patients with better prognosis have been already clearly identified, while in C-patients, in spite of some CNS functions improvement (respiration, brain stem reflexes), the outcome remained the same as earlier predicted.