Clinical state transitions during advanced life support (ALS) in in-hospital cardiac arrest

When providing advanced life support (ALS) in cardiac arrest, the patient may alternate between four clinical states: ventricular fibrillation/tachycardia (VF/VT), pulseless electrical activity (PEA), asystole, and return of spontaneous circulation (ROSC). At the end of the resuscitation efforts, either death has been declared or sustained ROSC has been obtained. The aim of this study was to describe and analyze the clinical state transitions during ALS among patients experiencing in-hospital cardiac arrest.

The defibrillator files from 311 in-hospital cardiac arrests at the University of Chicago Hospital (IL, USA) and St. Olav University Hospital (Trondheim, Norway) were analyzed (clinicaltrials.gov: NCT00920244). The transitions between clinical states were annotated along the time axis and visualized as plots of the state prevalence according to time. The cumulative intensity of the state transitions was estimated by the Nelson-Aalen estimator for each type of state transition, and for the intensities of overall state transitions. Between 70% and 90% of patients who eventually obtained sustained ROSC had progressed to ROSC by approximately 15-20 min of ALS, depending on the initial rhythm. Patients behaving unstably after this time period, i.e., alternating between ROSC, VF/VT and PEA, had a high risk of ultimately being declared dead.

We provide an overall picture of the intensities and patterns of clinical state transitions during in-hospital ALS. The majority of patients who obtained sustained ROSC obtained this state and stabilized within the first 15-20 min of ALS. Those who continued to behave unstably after this time point had a high risk of ultimately being declared dead.