Implications of an individualized resuscitation strategy using continuous rhythm and physiologic status assessment during ongoing CPR.

Background: Prior studies have proposed defibrillator biosignal algorithms which characterize cardiac arrest rhythm and physiologic status. We evaluated whether a novel, individualized resuscitation strategy that integrates multiple ECG and impedance-based algorithms could reduce CPR interruptions and better align rescuer actions with patient-specific physiology.

Methods: In a retrospective cohort of ventricular fibrillation out-of-hospital cardiac arrests, observed rescuer actions (rhythm analysis, shock delivery, pulse checks, and drug therapy) were compared to hypothetical actions recommended by the proposed individualized strategy. Misdirected drug therapy was defined as either (1) epinephrine when the algorithm predicted a spontaneous pulse or (2) antiarrhythmic during predicted bradyasystole. Clinically avoidable actions included delivering a shock without restoring return of spontaneous circulation (ROSC) and interrupting CPR for pulse assessment when no spontaneous pulse was present.

Results: Of 390 cases, 46% survived to hospital discharge. The individualized treatment strategy achieved comparable shock decision accuracy (95% sensitivity, 98% specificity) to observed care while decreasing median CPR interruption for shock from 12 to 6 s. The individualized strategy also identified 17% of 597 epinephrine and 9% of 248 antiarrhythmic administrations as misdirected. Following 1334 ventricular fibrillation shocks, the frequency of post-shock ROSC was 4% when its predicted probability was low versus 22% when not. During 1088 pulse checks, pulse was present in 5% when predicted probability of spontaneous pulse was low versus 35% when not.

Conclusions: An individualized resuscitation strategy could improve CPR interruption, medication administration, shock delivery, and pulse assessment. Prospective evaluation is required to assess clinical benefit.