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. 2022 Feb:171:33-40.
doi: 10.1016/j.resuscitation.2021.12.016. Epub 2021 Dec 21.

Paramedic rhythm interpretation misclassification is associated with poor survival from out-of-hospital cardiac arrest

H Hill Stoecklein  1 , Andrew Pugh  2 , M Austin Johnson  2 , Joseph E Tonna  2 , Michael Stroud  3 , Stavros Drakos  4 , Scott T Youngquist  5
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Paramedic rhythm interpretation misclassification is associated with poor survival from out-of-hospital cardiac arrest

H Hill Stoecklein et al. Resuscitation. 2022 Feb.

Abstract

Background: Early recognition and rapid defibrillation of shockable rhythms is strongly associated with survival in out of hospital cardiac arrest (OHCA). Little is known about the accuracy of paramedic rhythm interpretation and its impact on survival. We hypothesized that inaccurate paramedic interpretation of initial rhythm would be associated with worse survival.

Methods: This is a retrospective cohort analysis of prospectively collected OHCA data over a nine-year period within a single, urban, fire-based EMS system that utilizes manual defibrillators equipped with rhythm-filtering technology. We compared paramedic-documented initial rhythm with a reference standard of post-event physician interpretation to estimate sensitivity and specificity of paramedic identification of and shock delivery to shockable rhythms. We assessed the association between misclassification of initial rhythm and neurologically intact survival to hospital discharge using multivariable logistic regression.

Results: A total of 863 OHCA cases were available for analysis with 1,756 shocks delivered during 542 (63%) resuscitation attempts. Eleven percent of shocks were delivered to pulseless electrical activity (PEA). Sensitivity and specificity for paramedic initial rhythm interpretation were 176/197 (0.89, 95% CI 0.84-0.93) and 463/504 (0.92, 95% CI 0.89-0.94) respectively. No patient survived to hospital discharge when paramedics misclassified the initial rhythm.

Conclusions: Paramedics achieved high sensitivity for shock delivery to shockable rhythms, but with an 11% shock delivery rate to PEA. Misclassification of initial rhythm was associated with poor survival. Technologies that assist in rhythm identification during CPR, rapid shock delivery, and minimal hands-off time may improve outcomes.

Keywords: Cardiac arrest; Defibrillation; Shock accuracy; Tachycardia; Ventricular; Ventricular fibrillation.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Joseph E. Tonna was supported by a career development award (K23HL141596) from the National Heart, Lung, And Blood Institute (NHLBI) of the National Institutes of Health (NIH). M. Austin Johnson is a founder and stockholder of Certus Critical Care, Inc. Stavros Drakos is supported by funding from the AHA Heart Failure Strategically Focused Research Network (16SFRN29020000), the National Heart, Lung, And Blood Institute (NHLBI R01 HL135121-01 and NHLBI R01 HL132067-01A1), a Merit Review Award (I01 CX002291) through the U.S. Dpt of Veterans Affairs, and the Nora Eccles Treadwell Foundation. Scott Youngquist reports grant support from the NIH SIREN Collaborative (1U01NS099046-01A1, 1OT2HL156812-01, UH3HL145269), Collabs, Inc., and The ZOLL Foundation. All other authors report no conflicts of interest.

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