Insights into the epidemiology of cardiopulmonary resuscitation-induced consciousness in out-of-hospital cardiac arrest

Objectives To describe the characteristics and outcomes of cardiopulmonary resuscitation (CPR)-induced consciousness patients from a large database of out-of-hospital cardiac arrest (OHCA). Methods Included were adult patients, attended between January 2007 and December 2018 by the Queensland Ambulance Service, where resuscitation was attempted by paramedics. Manual review of records was undertaken to identify CPR-induced consciousness cases. Patients exhibiting purposeful limb/body movement during CPR, with or without displaying other signs, were considered to be CPR-induced consciousness. Characteristics and outcomes of CPR-induced consciousness patients were compared to those without CPR-induced consciousness. Results A total of 23 011 OHCA patients were included; of these, 52 (0.23%) were CPR-induced consciousness. This translates into an incidence rate of 2.3 cases per 1000 adult resuscitation attempts over 12 years. Combativeness/agitation was the most common sign of CPR-induced consciousness, described in 34.6% (18/52) of patients. CPR-induced consciousness patients had numerically higher rates of return of spontaneous circulation on hospital arrival (51.9% vs 28.6%), discharge survival (46.2% vs 15.1%) and 30-day survival (46.2% vs 14.7%), than those without CPR-induced consciousness; however, CPR-induced consciousness was not found to be an independent predictor of survival. Higher proportions of CPR-induced consciousness patients had arrest witnessed by paramedics, occurring in public places, of cardiac aetiology and initial shockable rhythm, than patients without CPR-induced consciousness. Conclusions CPR-induced consciousness in OHCA appears to be associated with higher survival rates. Standardised guidelines on recognition and management of CPR-induced consciousness remain to be established.