A prospective observational study to investigate the effect of prehospital airway management strategies on mortality and morbidity of patients who experience return of spontaneous circulation post cardiac arrest and are transferred directly to regional Heart Attack Centres by the Ambulance Service
Edwards, Timothy Robin
Introduction The most appropriate airway management technique for use by paramedics in out-of-hospital cardiac arrest is yet to be determined and evidence relating to the influence of airway management strategy on outcome remains equivocal. In cases where return of spontaneous circulation (ROSC) occurs following out-of-hospital cardiac arrest, patients may undergo direct transfer to a specialist heart attack centre (HAC) where the post resuscitation 12 lead ECG demonstrates evidence of ST elevation myocardial infarction. To date, no studies have investigated the role of airway management strategy on outcomes in this sub-set of patients. The AMICABLE (Airway Management In Cardiac Arrest, Basic, Laryngeal mask airway, Endotracheal intubation) study therefore sought to investigate the influence of prehospital airway management strategy on outcomes in patients transferred by the ambulance service directly to a HAC post ROSC. Methods Adults with ROSC post out-of-hospital cardiac arrest who met local criteria for transfer to a HAC were identified prospectively. Ambulance records were reviewed to determine prehospital airway management approach and collect physiological and demographic data. HAC notes were obtained to determine in-hospital course and quantify neurological outcome via the Cerebral Performance Category (CPC) scale. Neurologically intact survivors were contacted post discharge to assess quality of life via the SF-36 health survey. Statistical analyses were performed via Chi-square, Mann Whitney U test, odds ratios, and binomial logistic regression. Results A total of 220 patients were recruited between August 2013 and August 2014, with complete outcome data available for 209. The age of patients ranged from 22-96 years and 71.3% were male (n=149). Airway management was undertaken using a supraglottic airway (SGA) in 72.7% of cases (n=152) with the remainder undergoing endotracheal intubation (ETI). There was no significant difference in the proportion of patients with good neurological outcome (CPC 1&2) between the SGA and ETI groups (p=.286). Similarly, binomial logistic regression incorporating factors known to influence outcome demonstrated no significant difference between the SGA and ETI groups (Adjusted OR 0.725, 95% CI 0.337-1.561). Clinical and demographic variables associated with good neurological outcome included the presence of a shockable rhythm (p<.001), exposure to angiography (p<.001), younger age (p<.001) and shorter time to ROSC (p<.001). Due to an inadequate response rate (25.4%, n=15) analysis of SF36 data was limited to descriptive statistics. Limitations The study only included patients who achieved ROSC and met the criteria for direct transfer to a HAC. Results are therefore not generalisable to more heterogenous resuscitation populations. Accuracy of clinical decision making and ECG interpretation were not assessed and therefore some patients included in the study may have been inappropriately transferred to a HAC. The low SF-36 survey response rate limited the level of neurological outcome analysis that could be undertaken. Conclusion In this study, there was no significant difference in the proportion of good neurological outcomes in patients managed with SGA versus ETI during cardiac arrest. Further research incorporating randomised controlled trials is required to provide more definitive evidence in relation to the optimal airway management strategy in out-of-hospital cardiac arrest.