Continued on-site CPR could improve survival in out-of-hospital cardiac arrest
On-scene resuscitation of patients with out-of-hospital cardiac arrest may provide a better chance of survival to hospital discharge compared with intra-arrest transport, researchers reported.
According to findings published in JAMA, on-scene resuscitation may also confer better neurological outcomes for patients with out-of-hospital cardiac arrest compared with intra-arrest transport.
“These data demonstrate a marked heterogeneity in intra-arrest transport practices across emergency medical services (EMS) systems,” Brian Grunau, MD, MHSc, assistant professor in the department of emergency medicine at the University of British Columbia and emergency physician at St. Paul's Hospital in Vancouver, Canada, and colleagues wrote. “Although important differences in management may be expected between systems with variable structure and history, all EMS systems in this study had the same basic structure (strengthening internal validity) with protocols based on American Hospital Association guidelines and response teams with basic life support (BLS)-trained and advanced life support (ALS)-trained personnel (without out-of-hospital physicians).”
For this prospective study, investigators used data from the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry to identify 43,969 patients (median age, 67 years; 37% women) with out-of-hospital cardiac arrest. The primary outcome was survival to hospital discharge. The secondary outcome was survival with good functional outcomes (modified Rankin Scale score less than 3).
Within the overall cohort:
- 86% of cardiac arrests occurred in a private location;
- 49% were bystander- or EMS-witnessed;
- 22% had initial shockable rhythms;
- 97% were treated by out-of-hospital advanced life support; and
- 26% underwent intra-arrest transport.
Investigators found that survival to hospital discharge was lower among patients who received intra-arrest transport (4%) compared those who received continued on-scene resuscitation (8.5%), for a risk difference of 4.6% (95% CI, 4-5.1; adjusted RR = 0.48; 95% CI, 0.43-0.54).
Moreover, survival to discharge with favorable neurological outcome was lower among patients who received intra-arrest transport (2.9%) compared with those who received continued-on scene resuscitation (7.1%), with a risk difference of 4.2% (95% CI, 3.5-4.9; aRR = 0.6; 95% CI, 0.47-0.76).
“Although we defined cases as ‘intra-arrest transport’ if they remained in a pulseless state at the time of scene departure, the majority of survivors in this group were actually resuscitated prior to hospital arrival, suggesting that the resuscitation success in these cases was more likely owing to the prehospital efforts,” Grunau told Healio. “While some hospital-based physicians may consider the quality of prehospital-based resuscitation as inferior to that provided in hospital, our data suggest that EMSs prioritizing prehospital resuscitative efforts are achieving superior outcomes vs. comparators.”
Caution in changing EMS policy
“Based on data from this study, caution may be warranted with regards to changes in EMS policy favoring routine intra-arrest transport for the purpose of extracorporeal CPR candidacy assessment at the hospital, as most will likely prove ineligible, and overall survival statistics may actually worsen,” the researchers wrote. “Rather, in settings evaluating extracorporeal CPR provision for out-of-hospital cardiac arrest, systems might consider applying eligibly criteria prior to transport, which may mitigate these risks. Further study is required to determine the efficacy of intra-arrest transport plus extracorporeal CPR compared with exclusive on-scene resuscitation. Alternatively, out-of-hospital on-scene initiation of extracorporeal CPR may benefit from access to mechanical perfusion with-out the risks of hospital transport.”
Survival to discharge was associated with on-site resuscitation whether the out-of-hospital cardiac arrest was EMS-witnessed or not (RR when witnessed = 0.58; 95% CI, 0.5-0.66; RR not witnessed = 0.32; 95% CI, 0.25-0.41).
Similarly, survival to discharge was more likely to occur with on-site resuscitation compared with intra-transport arrest regardless of whether the patient had a shockable rhythm (RR for shockable = 0.55; 95% CI, 0.45-0.68; RR for not shockable = 0.63; 0.53-0.74).
“The decision not to transport a patient with refractory out-of-hospital cardiac arrest to hospital may be seen as providing a less aggressive resuscitative effort,” Grunau said in an interview. “However, the true question is not whether to transport to hospital or terminate the resuscitation, but rather whether to transport to hospital or continue resuscitation on-scene. The appropriate duration of resuscitation prior to consideration of termination is a separate clinical question, which should not cloud the clinical question of optimal resuscitation location.”
Challenging ‘scoop and run’
“These findings challenge the ‘scoop and run’ model for out-of-hospital cardiac arrest by suggesting a strong clinical benefit associated with continuing the resuscitation on scene until a definitive outcome has been achieved,” Alexander X. Lo, MD, PhD, associate professor of emergency medicine at the Feinberg School of Medicine at Northwestern University, wrote in a related editorial. “Before embracing this model, and substantially changing the out-of-hospital approach to out-of-hospital cardiac arrest, more definitive studies, including high-quality randomized trials, will be needed.
“Region-specific variables may behave in a more sophisticated fashion than simple confounding factors,” Lo wrote. “While the results of the study by Grunau et al represent the summary experience across the 10 diverse study sites and 192 EMS systems, the potentially significant heterogeneity between the patient populations and between EMS systems challenge both the generalizability of the study findings and the likelihood that individual communities and EMS systems would enthusiastically adopt a practice change as a result of this study.”
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