Should vasopressin replace adrenaline for endotracheal drug administration?

Objective: Arginine vasopressin was established recently as a drug of choice in the treatment of cardiac arrest and in retractable ventricular fibrillation; however, the hemodynamic effect of vasopressin following endotracheal drug administration has not been fully elucidated. We compared the effects of endotracheally administered vasopressin vs. adrenaline on hemodynamic variables in a canine model, and we investigated whether vasopressin produces the same deleterious immediate blood pressure decrease as did endotracheal adrenaline in the canine model. Design: Prospective controlled study. Setting: Animal laboratory in Tel-Aviv University, Israel. Subjects: Five adult mongrel dogs weighing 6.5-20 kg. Interventions: Dogs were anesthetized; each dog was intubated orally, and both femoral arteries were cannulated for the measurement of arterial pressure and for sampling blood gases. Each dog was studied four times, 1 wk apart, by using the same protocol for injection and anesthesia: endotracheal placebo (10 mL NaCl 0.9%,), endotracheal vasopressin (1 units/kg), endobronchial adrenaline (0.1 mg/kg), and endotracheal adrenaline (0.1 mg/kg). Following placebo, vasopressin, and adrenaline instillation, five forced manual ventilations were delivered with an Ambu bag. Each dog was its own control. Measurements and Main Results: Following placebo or drug administration, heart electrocardiography and arterial pressures were continuously monitored with a polygraph recorder for 1 hr. Endotracheal vasopressin produced an immediate increase of diastolic blood pressure (from 83 ± 10 mm Hg [baseline] to 110 ± 5 mm Hg at 1 min postinjection). This response lasted > 1 hr. In contrast, both endotracheal and endobronchial administration of adrenaline produced an early and significant (p < .05) decrease in diastolic and mean blood pressures. The diastolic blood pressure increase from 85 ± 10 mm Hg to 110 ± 10 mm Hg took an ill-afforded 55 secs following endotracheal adrenaline. Diastolic blood pressure was significantly (p < .05) higher following vasopressin compared with adrenaline administration in both routes. Conclusions: Vasopressin accomplishes its hemodynamic effect, particularly on diastolic blood pressure, more rapidly, vigorously, and protractedly and to a significant degree compared with both endotracheal and endobronchial adrenaline. Evaluation of the effects of endotracheal vasopressin in a closed chest cardiopulmonary resuscitation model is recommended.