Multiple Shock Failures during Resuscitation: Risk Factors and Prognostic Implications

ABSTRACT

PURPOSE: Electrical shock is not always followed by a perfusing rhythm, and multiple shock failure (MSF) is common during CPR. We sought to investigate its risk factors and prognostic implications. METHODS: Adult OHCA patients with emergency department (ED) ACLS attempts were identified from a tertiary hospital OHCA registry extending from 2008 to 2012. Shock failure was defined as any electrical shock attempt not followed by a pulse-generating rhythm. Patients were assigned to one of three groups based on the number of shock failures 1) MSF ≥3 electrical shock failures before the first ROSC or CPR termination (if there was no ROSC), 2) early shock success (ESS) pulse-generating rhythm achieved within 3 electrical shock attempts and 3) others all remaining patients. Baseline characteristics, initial laboratory measurements, and outcomes were compared. RESULTS: A total of 590 patients were included. There was no significant difference in baseline characteristics between the MSF group (n=49) and the early shock success group (n=50) except in its higher proportion of presumed cardiac aetiology. The MSF group showed less severe metabolic acidosis and coagulopathy on ED arrival and better renal function and higher haematocrit and serum albumin levels compared with the ESS group. MSF was associated with less sustained ROSC, but was also associated with more survival discharge and better long-term neurologic outcomes after sustained ROSC. CONCLUSION: MSF may indicate heart-specific problems rather than severe metabolic derangements. Better long-term outcomes can be expected once sustained ROSC is achieved, therefore, this phenomenon warrants more focused research.