Efficacy of Several Modes of Continuous-Flow Insufflation for Resuscitation of a Canine Model of Acute Respiratory Arrest

Study objective: 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. Methods: 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). Results: 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 Pa o 2, 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. Conclusion: 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. [Barnas GM, Smalley AJ, Miller J, Park SG, Delaney PA, Mackenzie CF: Efficacy of several modes of continuous-flow insufflation for resuscitation of a canine model of acute respiratory arrest. Ann Emerg Med May 1996;27:617-624.]