The Pre-brief
A 39-year-old man collapses in the street after his usual morning run. A BLS crew arrives quickly and notes he is in cardiac arrest. CPR is commenced. The paramedic supervisor arrives on scene a few minutes later and advises the crew to quickly package the patient up and transport to the nearest community hospital, 15 minutes away. Return of spontaneous circulation (ROSC) has still not been achieved.
“The things this guy will need are better done in the hospital.” he says.
One of medics scratches his chin and wonders if that is really true…especially as he has recently read a paper in JAMA while revising for his paramedic course.
The Paper:
Grunau et al recently published their North American trial entitled: Association of Intra-arrest Transport vs Continued On-Scene Resuscitation With Survival to Hospital Discharge Among Patients With Out-of-Hospital Cardiac Arrest. This is based on the notion questioning the benefit of on-scene versus in-hospital management of patients still in non-traumatic arrest.
What did the Authors do?
This was a prospective cohort trial over 10 North American EMS agencies, with data being consecutively collected from April 2011 to June 2015. Data was made available through the Resuscitation Outcomes Consortium (ROC) Cardiac Epidemiologic Registry for nontraumatic cardiac arrest. Patients were followed through their course until hospital discharge or death. Comparisons were between groups that were treated on scene until ROSC, or those who were transported prior to ROSC being achieved.
The primary outcome was survival to hospital discharge, and the secondary outcome was survival with favorable neurological outcome (which was defined as a modified Rankin score of <3) at the time of hospital discharge.
Ultimately the study authors recruited 43,969 patients. Their median age was 67 years, and the majority were male (63%). Almost half (49%) were witnessed arrests by either bystanders or EMS personnel. 22% had an initial rhythm that was shockable. 97% were treated by out-of-hospital advanced life support, and 26% underwent intra-arrest transport. 26% were transported to the hospital with CPR ongoing.
What Were the Outcomes?
Survival to hospital discharge varied in the two groups: 12.6% for those who were managed on scene until ROSC, versus 3.8% for patients with intra-arrest transport. With propensity matching (of 27,705 patients with 1:1 matching), the numbers were slightly different but still favored management on scene (8.5% survival for on-scene management versus 4.0% for those transported intra-arrest) (risk difference, 4.6% [95% CI, 4.0%- 5.1%]). Subgroup analysis showed that witnessed arrests and all rhythms (shockable or non-shockable) favored higher survival to discharge when managed on scene.
Importantly, neurologic outcomes varied between groups: 7.1% had a favorable outcome with on-scene management versus only 2.9% who underwent intra-arrest transport (risk difference, 4.2% [95% CI, 3.5%-4.9%]).
What Were the Limitations?
Of course every study has challenges. This was not a randomized clinical trial, and hence findings are more association rather than true cause and effect. In addition, there remains a problem of generalizability between prehospital systems. Although this study included several different agencies, the majority of responses were by ALS-capable units. Whether these results translate to primary BLS-based agencies, and in fact whether variations of care protocols across agencies allow for similar results, is not clear. This is a big challenge with many prehospital studies.
Additional limitations included the possibility of prognostication bias for certain patients, the exclusion of patients utilizing mechanical compression devices, and the utilization of protocols during a time period that may not hold relevance today as the science has evolved.
The Debrief
The pendulum has swung both ways in terms of the management of out-of-hospital cardiac arrest. What is better? Many interventions that we thought would help (intubation, epinephrine) have variable evidence to them and may actually delay the interventions that have been shown to help which are appropriate chest compressions and early defibrillation of shockable rhythms. Transporting a patient without achieving ROSC means that there will be interruptions in chest compressions. The quality of those compressions in the back of a moving ambulance is questionable at best, not to mention the risks to the prehospital crew. So it certainly makes sense to do effective, high-quality care at the scene before transporting as this paper suggests, and in fact empowering bystanders to provide this while waiting for help to arrive.
Further food for thought however is the advent of extracorporeal cardiopulmonary resuscitation (ECPR) – earlier initiation in eligible patients may well save lives, and this is the premise of developing either prehospital ECPR capability abroad (and in some US cities) or streamlining access to it in the hospital (as in Minnesota). Certainly if the system supports such interventions, there needs to be close collaboration between the intervention team, EMS medical directors, and EMS personnel to develop appropriate protocols for care.
However, since this capability is still not available outside of specific centers, reinforcing effective management on scene until ROSC is achieved should be the norm for now.
References
Grunau B, Kime N, Leroux B, et al. Association of Intra-arrest Transport vs Continued On-Scene Resuscitation With Survival to Hospital Discharge Among Patients With Out-of-Hospital Cardiac Arrest. JAMA 2020 Sep;324(11):1058-1067 PMID: 32930759
Youngquist ST, Tonna JL, Bartos JA, et al. Current Work in Extracorporeal Cardiopulmonary Resuscitation. Crit Care Clin 2020 Oct;36(4):723-735 PMID: 32892825
