Clinical paperAcute lung injury and recovery in patients with refractory VT/VF cardiac arrest treated with prolonged CPR and veno-arterial extracorporeal membrane oxygenation
Introduction
Approximately 350,000 out-of-hospital cardiac arrests (OHCA) occur in the United States each year, with one-third caused by shockable rhythms1, 2, 3, 4, 5. Extracorporeal cardiopulmonary resuscitation (ECPR) with veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly used to provide hemodynamic stability for patients with cardiac arrest refractory to standard ACLS with significant increases in survival1, 5, 6, 7, 8. When return of spontaneous circulation (ROSC) is achieved, a systemic inflammatory response develops which, combined with ischemia/reperfusion injury and trauma from prolonged CPR, results in multi-system organ failure including pulmonary injury9, 10, 11, 12, 13, 14, 15.
The lung injury observed in V-A ECMO patients has been attributed to increased left ventricular (LV) afterload resulting in increased left ventricular end-diastolic pressure and pulmonary edema16. However, the etiology of lung injury in refractory OHCA is further complicated by trauma from chest compressions, an unprotected airway resulting in aspiration, barotrauma and volutrauma associated with the imprecision of bag valve mask ventilation, and need for anticoagulation for V-A ECMO17, 18, 19, 20. There are limited data systematically evaluating the type, extent, and duration of lung injury in patients who are treated with ECPR.
We evaluated patterns of lung injury associated with ventricular tachycardia or ventricular fibrillation (VT/VF) OHCA supported with ECPR. We hypothesize that lung injury is common post arrest with initial imaging and lower compliance correlating with worse outcomes.
Section snippets
Study population
Consecutive patients presenting with refractory VT/VF OHCA, who were treated with the Minnesota Resuscitation Consortium (MRC) ECPR protocol between December 2015 and January 2020, were eligible for inclusion. Procedures were followed in accordance with the ethical standards of the IRB and in accordance with the Helsinki Declaration of 1975. The study was reviewed and approved by the Institutional Review Board (IRB) at the University of Minnesota (IRB #1703M11301, 10/17/2021, ICU care for
Results
Between December 2015 and January 2020, 215 consecutive patients presented with refractory VT/VF OHCA. After excluding those that did not meet the study criteria, 138 patients were included (Fig. 1). The majority of patients were male (81%) with a mean age 57.2 ± 11.9 years (Table 1). The mean CPR time was 64.3 ± 16.1 minutes. The mean APACHE II and SOFA scores on admission were 30.5 ± 4.6 and 9.2 ± 2.9, respectively.
A total of 48/138 (34.8%) survived, 31/138 (22.5%) developed brain death, and
Discussion
This study explores the manifestations and associations of lung injury in refractory OHCA patients supported with ECPR, as well as the characteristics of their lung recovery. Lung injury is common9, 17, 18 with lung compliance being severely reduced in the initial post-arrest period, but improving with supportive management. Despite decreased pulmonary compliance V-A ECMO allowed for lung protective ventilation potentially reducing further injury. As we hypothesized we found that lung injury
Conclusion
Lung injury is common in post-cardiac arrest syndrome with high rates of aspiration, and pulmonary edema. Compliance is poor in the initial post arrest period but as in ARDS, improves with ECMO support. The use of VA-ECMO allows the titration of ventilator parameters to ensure lung protective ventilation. This is evidenced in our study by the occurrence of lung recovery independent of initial compliance, peak pressure, driving pressure and CT appearance.
CRediT authorship contribution statement
Alejandra Gutierrez: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writing – original draft, Visualization. Rajat Kalra: Conceptualization, Data curation, Methodology, Writing – review & editing, Visualization. Andrea M. Elliott: Methodology, Visualization, Writing – review & editing. Alexandra Marquez: Methodology, Visualization, Writing – review & editing. Demetris Yannopoulos: Methodology, Investigation, Writing – review & editing, Validation, Supervision.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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