The Effect of Etiology of Arrest on the Probability of Attaining ROSC Among Patients Presenting With Pulseless Electrical Activity

Introduction—Numerous studies have investigated factors affecting the likelihood of return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA). One of the factors associated with ROSC is a shockable presenting rhythm whereby patients presenting in VF/VT have a higher likelihood of ROSC compared to patients presenting with asystole or PEA. However, little is known about the factors affecting the likelihood of ROSC among the subset of patients initially presenting in PEA.

Objective—This study seeks to identify the relationship between ROSC and arrest etiology for patients with a presenting rhythm of PEA.

Methods—The authors conducted a retrospective analysis of cardiac arrest using data from the North Carolina Prehospital Medical Information System (PREMIS). Inclusionary criteria were adult patients (≥18 years) who suffered cardiac arrest with an initial rhythm of PEA between January 2012 and June 2014. Multivariate logistic regression calculated the odds ratio (OR) of ROSC for cardiac arrest patients in PEA for etiologies of drowning, electrocution, cardiac, respiratory and trauma, while controlling for the potentially confounding variables of patient age, gender and minority status; layperson/first responder CPR; EMS dispatch to pressor administration interval; and witnessed arrest.

Results—Of the 1,894 patients meeting the inclusionary criteria, 59.2% were male, 37.9% were non-Caucasian, and 45.6% received bystander and/or first responder CPR. Cardiac was the most frequent etiology (75.8%), followed by respiratory (17.1%), trauma (6.9%), drowning (0.2%) and electrocution (0.1%). The mean patient age was 66.7 (±16.4) years, and the mean EMS response time was 7.8 (±4.1) minutes. Overall, 50.1% of patients attained ROSC. The likelihood of ROSC decreased by 3% for each minute of delay in epinephrine administration (OR 0.97, p<0.01). ROSC was more likely with layperson/first responder CPR (OR 1.64, p<0.01). Compared to traumatic arrests, arrests of cardiac (OR 1.85, p<0.01) and respiratory (OR 3.35, p<0.01) etiologies were more likely to attain ROSC. Age, gender, minority status, witnessed arrest and drowning and electrocution arrest etiologies were not statistically significant predictors of ROSC.

Conclusion—Cardiac arrest etiology is a statistically significant predictor of ROSC for patients presenting in PEA. Compared to traumatic arrests, arrests of cardiac and respiratory etiologies were more likely to attain ROSC.