A study of nonshockable out of hospital cardiac arrest survival showed significant improvement in short- and long-term survival and neurological outcome after implementation of a protocol consistent with CPR guidelines that prioritised chest compressions. These improvements were especially evident among arrests attributable to a cardiac cause, although there was no evidence of harm among arrests attributable to a noncardiac cause.
This was not a randomised trial so unrecognised factors may have contributed to the improved outcome in addition to the change in CPR protocol. However, it is interesting as it provides up to date survival rates from a large population sample: Non shockable out of hospital cardiac arrests achieve return of spontaneous circulation in 34%, 6.8% are discharged from hospital (5.1% with a favourable neurological outcome), and 4.9% survived one year.
The breakdown between PEA and asystole is of course telling, and unsurprising, with 12.8% versus 1.1% being discharged with a favourable neurological outcome, respectively. I would imagine then that some of the PEA patients had beating hearts with hypotension extreme enough to cause pulselessness (pseudo-electromechanical dissociation) – clinically a ‘cardiac arrest’ but really nothing of the sort, and the reason we use cardiac ultrasound to prognosticate.
BACKGROUND: Out-of-hospital cardiac arrest (OHCA) claims millions of lives worldwide each year. OHCA survival from shockable arrhythmias (ventricular fibrillation/ tachycardia) improved in several communities after implementation of American Heart Association resuscitation guidelines that eliminated “stacked” shocks and emphasized chest compressions. “Nonshockable” rhythms are now the predominant presentation of OHCA; the benefit of such treatments on nonshockable rhythms is uncertain.
METHODS AND RESULTS: We studied 3960 patients with nontraumatic OHCA from nonshockable initial rhythms treated by prehospital providers in King County, Washington, over a 10-year period. Outcomes during a 5-year intervention period after adoption of new resuscitation guidelines were compared with the previous 5-year historical control period. The primary outcome was 1-year survival. Patient demographics and resuscitation characteristics were similar between the control (n=1774) and intervention (n=2186) groups, among whom 471 of 1774 patients (27%) versus 742 of 2186 patients (34%), respectively, achieved return of spontaneous circulation; 82 (4.6%) versus 149 (6.8%) were discharged from hospital, 60 (3.4%) versus 112 (5.1%) with favorable neurological outcome; 73 (4.1%) versus 135 (6.2%) survived 1 month; and 48 (2.7%) versus 106 patients (4.9%) survived 1 year (all P≤0.005). After adjustment for potential confounders, the intervention period was associated with an improved odds of 1.50 (95% confidence interval, 1.29-1.74) for return of spontaneous circulation, 1.53 (95% confidence interval, 1.14-2.05) for hospital survival, 1.56 (95% confidence interval, 1.11-2.18) for favorable neurological status, 1.54 (95% confidence interval, 1.14-2.10) for 1-month survival, and 1.85 (95% confidence interval, 1.29-2.66) for 1-year survival.
CONCLUSION: Outcomes from OHCA resulting from nonshockable rhythms, although poor by comparison with shockable rhythm presentations, improved significantly after implementation of resuscitation guideline changes, suggesting their potential to benefit all presentations of OHCA.
Impact of changes in resuscitation practice on survival and neurological outcome after out-of-hospital cardiac arrest resulting from nonshockable arrhythmia
Circulation. 2012 Apr 10;125(14):1787-94