ObjectiveArginine 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.DesignProspective controlled study.SettingAnimal laboratory in Tel-Aviv University, Israel.SubjectsFive adult mongrel dogs weighing 6.5–20 kg.InterventionsDogs 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 ResultsFollowing 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.ConclusionsVasopressin 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.