Out-of-hospital cardiac arrest (OHCA) remains a major cause of death worldwide. Ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) are the most treatable causes of OHCA, and rapid defibrillation using pads placed in either the anterior-posterior (AP) or anterior-lateral (AL) position increases the chances of survival with good neurological outcomes. However, many patients with shockable rhythms like VF or pVT do not respond to the initial defibrillation attempts. While extensive research has been conducted on the optimal pad placement for cardioversion in atrial fibrillation, no prospective studies have been done to determine the ideal initial pad positioning for OHCA due to VF or pVT. A new study now suggests that the initial positioning of defibrillator pads may significantly impact the likelihood of restoring spontaneous circulation after defibrillation in individuals experiencing out-of-hospital cardiac arrest.

In the observational study published in the journal JAMA Network Open, researchers at the Oregon Health & Science University (Portland, OR, USA) analyzed data from the Portland Cardiac Arrest Epidemiologic Registry, which tracked defibrillation pad placement from July 1, 2019, through June 30, 2023. Researchers reviewed 255 cases treated by Tualatin Valley Fire & Rescue, focusing on whether the defibrillator pads were placed in the front and side (AL) or front and back (AP). The findings revealed that placing the pads in the front and back increased the odds of returning spontaneous circulation by 2.64 times compared to the front-and-side placement.

Current practice among healthcare professionals suggests that both pad positions—front and side, or front and back—are equally effective during cardiac arrest. However, the study's results indicate a potential advantage in placing the pads on the front and back, possibly because this configuration more effectively "sandwiches" the heart, allowing the electrical current to reach the organ more comprehensively. The researchers stressed that this study is observational and not a definitive clinical trial, but the findings suggest that front-and-back pad placement may improve outcomes in cardiac arrest cases. However, practical limitations exist, such as when patients are overweight or in positions that make front-and-back placement difficult. Ultimately, pad positioning is just one of several factors that contribute to the successful treatment of cardiac arrest.

“The key is, you want energy that goes from one pad to the other through the heart,” said senior author Mohamud Daya, M.D., professor of emergency medicine in the OHSU School of Medicine. 

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