Background-Active compression decompression cardiopulmonary resuscitation (ACD-CPR) plus a decrease in intrathoracic pressure during the decompression phase of CPR have been shown previously to result in improved hemodynamics when compared with standard CPR. We hypothesized that these interventions would increase survival rates with favorable neurologic function after out-of-hospital cardiac arrest (OOHCA) when compared with standard CPR.

BackgroundPrevious studies have found particulate matter (PM) < 2.5 μm in aerodynamic diameter (PM2.5) associated with heart disease mortality. Although rapid effects of PM2.5 exposure on the cardiovascular system have been proposed, few studies have investigated the effect of short-term exposures on out-of-hospital cardiac arrest (OHCA).ObjectivesWe aimed to determine whether short-term PM2.5 exposures increased the risk of OHCA and whether risk depended on subject characteristics or presenting heart rhythm.MethodsA case–crossover analysis determined hazard ratios (HRs) for OHCAs logged by emergency medical systems (EMS) versus hourly and daily PM2.5 exposures at the time of the OHCA and for daily and hourly periods before it.ResultsFor all OHCAs (n = 1,374), exposures on the day of the arrest or 1–3 days before arrest had no significant effect on the incidence of OHCA. For cardiac arrests witnessed by bystanders (n = 511), OHCA risk significantly increased with PM2.5 exposure during the hour of the arrest (HR for a 10-μg/m3 increase in PM2.5 exposure = 1.12; 95% confidence interval, 1.01–1.25). For the subsets of subjects who were white, 60–75 years of age, or presented with asystole, OHCA risk significantly increased with PM2.5 during the hour of the arrest (HRs for a 10-μg/m3 increase in PM2.5 = 1.18, 1.25, or 1.22, respectively; p < 0.05). HR generally decreased as the time lag between PM2.5 exposure and OHCA increased.ConclusionThe results suggest an acute effect of short-term PM2.5 exposure in precipitating OHCAs, and a need to investigate further the role of subject factors in the effects of PM on the risk of OHCA.

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Gasping during CPR was independently associated with increased 1-year survival with CPC ≤2, regardless of the first recorded rhythm. These findings underscore the importance of not terminating resuscitation prematurely in gasping patients and the need to routinely recognize, monitor, and record data on gasping in all future cardiac arrest trials and registries.