Efficacy of several modes of continuous-flow insufflation for resuscitation of a canine model of acute respiratory arrest.

Abstract

To test the efficacy of several modes of continuous-flow insufflation on the maintenance of physiologic parameters in a model of respiratory arrest, and the effect of these modes on neurologic outcome. Anesthetized dogs were slowly infused with tetrodotoxin over 75 minutes to the point of respiratory arrest. We used two different modes of continuous-flow insufflation: endobronchial insufflation (EI) of air 3 cm distal to the carina (.25 or 1.0 L.kg-1.min-1); and tracheal insufflation of oxygen (TRIO) 1 cm proximal to the carina (.08 or .2 L.kg-1.min-1). EI at either flow rate provided ventilation sufficient to allow the dogs to recover effective spontaneous breathing and be removed from ventilation after 4 hours. By this time, almost all cardiovascular variables and blood gas values were normal. TRIO at .2 L.kg-1.min-1 also resulted in successful recovery, although Pa02, as well as systemic and pulmonary arterial pressures and vascular resistances, remained increased at the end of the 4-hour period. TRIO at the low flow rate, however, resulted in deterioration of blood gas values and systemic arterial pressure; dogs required conventional mechanical ventilation after 45 minutes of low-flow TRIO. EI can be used to maintain oxygenation in acute respiratory arrest when conventional techniques are not feasible; TRIO at .2 L.kg-1.min-1 is also effective.