AIRWAY PROTECTION DURING EXPERIMENTAL CPR

Background: Experimental studies recently demonstrated that positive p ressure ventilation may not be essential for initial cardiopulmonary r esuscitation. Nevertheless, oxygen enrichment of inspired gas mixtures and spontaneous gasping were associated with increased resuscitabilit y and survival after cardiac arrest, However, as yet unresolved is the benefit of early airway control under conditions simulating ''sudden death'' due to ventricular fibrillation. Methods: Twenty adult, male S prague-Dawley rats were randomly assigned to one of two groups in whic h the airway was unprotected or protected by an oropharyngeal airway o f our design, Cardiac arrest was induced by an alternating cut-rent de livered to the right ventricular endocardium. Oxygen was delivered to a hood that was loosely applied over the head of the each animal at a flow rate of 1 L/min, Precordial compression was initiated after 4 min of untreated ventricular fibrillation and defibrillation was attempte d 6 min later, After spontaneous circulation had been restored, a trac heostomy was performed and the animals were mechanically ventilated wi th 100% oxygen for an additional interval of 1 h, Animals were then re turned to their cages and observed for an additional 24 h. Results: Sp ontaneous circulation was restored in each of the animals who had an o ropharyngeal airway and nine of ten animals in the absence of an artif icial airway, In each group, seven animals survived for more than 24 h , Animals in which the airway had been protected had significantly gre ater frequency of spontaneous gasping (28+/-13/min vs 13+/-9/min; p<0. 05) and significantly higher arterial oxygen saturation (77+/-19% vs 5 5+/-25%; p<0.05). Conclusion: In the setting of experimental cardiac r esuscitation, the insertion of an artificial airway increased the freq uency of spontaneous gasping and arterial oxygenation. Nevertheless, n o significant differences in resuscitability or postresuscitation surv ival were associated with insertion of the artificial airway.