A new study strongly supports the idea that we will save more lives if we stay on scene and resuscitate cardiac arrest patients until we achieve ROSC. The study compared cardiac arrest patients who were transported only after they achieved ROSC to those who were transported while still in cardiac arrest. While this study has limitations (see below), the difference in survival to hospital discharge between the two groups was stark:
- 8.5% survived if transport was delayed until ROSC was achieved
- 4.0% survived if transport was started prior to ROSC
The difference was more pronounced when they looked at neurologically intact survival:
- 7.1% survived if transport was delayed until ROSC was achieved
- 2.9% survived if transport was started prior to ROSC
I’ve included one of the figures from the study, which breaks down survival by EMS agency and shows that EMS agencies that elected to transport prior to achieving ROSC had the worst cardiac arrest survival.
Association of Intra-arrest Transport vs Continued On-Scene Resuscitation With Survival to Hospital Discharge Among Patients With Out-of-Hospital Cardiac Arrest, Grunau B, Kime N, Leroux B, et al. JAMA. 2020;324(11):1058–1067. doi:10.1001/jama.2020.14185
The study was large and well done. It looked at 27,705 North American EMS patients from multiple EMS systems from 2011 to 2015. Limitations of the study include (i) that it was observational, and thus can cannot prove that more patients survived because transport was delayed until ROSC; it can only show an association, (ii) it did not look at the use of mechanical CPR (e.g. the LUCAS) during extrication and transport, and (iii) it looked only at non-traumatic cardiac arrest.
Why do more patients survive if we resuscitate on scene rather than “scoop and run”? The answer is straightforward: on average, we do terrible CPR while extricating the patient from the house and in the back of the ambulance. We know that only two therapies have ever been shown to make a difference in cardiac arrest: good quality compressions and defibrillation. Any interruption of CPR for more than 10 seconds diminishes effectiveness. Performing CPR on scene where the patient is found is recommended because we can deliver fantastic CPR in those circumstances; once we begin to move the patient, interruptions and poor quality CPR become the norm.
A few other points worth mentioning:
In the study, for the subset of patients that were resuscitated at least 30 minutes on scene, those who were transported in cardiac arrest did slightly better than those who remained on scene for longer. While we can’t know for sure, this probably reflects the fact that the EMS crews decided to stop resuscitation for those that remained on scene. That is, after 30 minutes, they were choosing to transport those patients that might potentially benefit from further resuscitation, and not transporting those where further resuscitation seemed futile.
Interestingly, for the subset of patients who were transported while still in cardiac arrest but who ultimately survived, the majority were successfully resuscitated in the ambulance while still on the way to the hospital, not at the hospital. This undercuts the argument that we should transport because at the hospital “more advanced therapies” can be administered that we don’t have available to us in the field. While this may turn out to be true in a very limited number of cases, this study suggests that bringing a patient to the hospital in cardiac arrest rarely makes a difference. What truly matters is high quality resuscitation, whether on scene or in the back of the ambulance.
Finally, this study helps prehospital providers stratify which cardiac arrest patients are likely to survive. The study looked at three factors that were independently associated with survival to hospital discharge:
- ROSC on scene
- Receiving at least one defibrillation shock (i.e. having a shockable rhythm at some point during resus)
- Cardiac arrest witnessed by EMS
Out of 27,705 patients in the study, 5,563 lacked all three criteria. Only 79 of those patients survived (0.2% of the total 27,705; 1.4% of the 5,563).
Prehospital cardiac arrest care has continued to improve since 2015 (the last year included in the study). It’s likely that today a larger percentage of patients are resuscitated successfully in the field.
This study does not undercut the idea that some patients who remain in cardiac arrest may benefit from either extended resuscitation or from therapies that are only available at the hospital. But it does suggest that, at least presently, delivery of the patient to the hospital and hospital-based therapies do not have a significant impact on survival. While transport in cardiac arrest may help a very small number of patients, focusing our efforts on delivering the highest quality care possible on scene will save the most lives.