A study led by Dr. Wulfran Bougouin published in the European Heart Journal analyzed out of hospital cardiac arrests (OHCA) and compared outcomes in patients who received and did not receive extracorporeal cardiopulmonary resuscitation (CPR). Dr. Bougouin and his team found that 4% of OHCAs were treated with extracorporeal-CPR and this was not associated with an increased hospital survival rate.
Only around 10% of patients with an OHCA survive. Refractory cardiac arrest, despite the use of advanced life support measures, is common and can lead to poor outcomes including irreversible brain damage. Extracorporeal membrane oxygenation (ECMO) is a device that provides cardiac and respiratory support to those unable to sustain adequate gas exchange or perfusion. The combination of CPR and ECMO is referred to as extracorporeal-CPR. Theoretically, extracorporeal-CPR could increase organ perfusion and therefore lead to improving OHCA outcomes. However, extracorporeal CPR is both time and resource consuming and requires a certain degree of medical expertise. The investigators aimed to compare outcomes of OHCA in those managed with extracorporeal CPR with those managed with regular CPR.
“In our large population-based registry, 4% of patients with OHCA received extracorporeal-CPR. Extracorporeal-CPR was not associated with improved outcome compared with conventional-CPR. Extracorporeal-CPR might be best reserved for patients with features associated with better extracorporeal-CPR outcomes, i.e. an initial shockable rhythm and transient ROSC.” – Dr. Wulfran Bougouin, M.D.
Using a prospective registry-based in Paris that prospectively follows up patients with OHCAs, the investigators identified all patients with an OHCA that was not due to an extracardiac cause (such as trauma, drowning, drug overdose, etc.). Data on prehospital care and information surrounding the OHCA encounter as well as outcomes were recorded. The primary outcome was survival to hospital discharge. The secondary outcome was determined as a favorable neurological outcome (defined as Cerebral Performance Category 1 or 2).
Of the 24,885 OHCAs in the registry, 13,191 were sudden cardiac arrests of suspected cardiac cause and were included in the study. Of those patients, 525 (4%) received an attempt at extracorporeal-CPR and 467 (89%) of those were successful. Patients in the extracorporeal group were younger, more likely to be male, more likely to receive bystander CPR, had an initial shockable rhythm, were less likely to experience the return of spontaneous circulation (ROSC), and were more likely to have CPR lasting for more than 30 minutes. There was no significant difference in survival to hospital discharge rates between the two groups (8.4% in the extracorporeal-CPR group vs 8.6% in the conventional-CPR group, p = 0.91). Even when adjusting for differences in baseline characteristics, the difference did was not statistically significant. In the patients who received extracorporeal-CPR, the three factors identified that were associated with survival were the presence of an initial shockable rhythm, transient ROSC during initial resuscitation, and prehospital ECMO implantation. Prehospital ECMO implantation was also associated with favorable neurological outcomes (OR 2.9, 95% CI 1.3-6.4, p = 0.008). Of those who survived, a low proportion of patients in the extracorporeal-CPR group had a favorable neurological outcome (84% vs 96%, p = 0.001).
The findings of this study suggest that extracorporeal-CPR is not associated with improved outcomes. While previous smaller studies have demonstrated improved outcomes with extracorporeal-CPR, the findings of this study suggest otherwise. However, there were certain features that were associated with better outcomes. These included an initial shockable rhythm and transient ROSC. In this subset of patients, extracorporeal-CPR could potentially be considered. While this study does offer a real-life picture of extracorporeal-CPR use and outcomes, it does come with its limitations. The observational nature of this study prevents any statements of causality. There is currently an ongoing randomized trial that could potentially address this issue.