The characteristics of postcountershock pulseless electrical activity may indicate the outcome of CPR

ECG changes during resuscitation of patients with initial pulseless electrical activity are associated with return of spontaneous circulation

BACKGROUND

Pulseless electrical activity (PEA) is a frequent initial rhythm in cardiac arrest, and ECG characteristics have been linked to prognosis. The aim of this study was to examine the development of ECG characteristics during advanced life support (ALS) and cardiopulmonary resuscitation (CPR) in cardiac arrest with initial PEA, and to assess any association with survival.

METHODS

Patients with in-hospital cardiac arrest with initial PEA at St. Olav Hospital (Trondheim, Norway) over a three-year period were included. A total of 2187 combined observations of QRS complex rate (heart rate) and QRS complex width for the duration of ALS were determined from defibrillator recordings from 74 episodes of cardiac arrest.

RESULTS

Increasing heart rate and decreasing QRS complex width during ALS was significantly more prevalent in patients who obtained return of spontaneous circulation compared to patients who were declared dead.

CONCLUSION

Changes in ECG characteristics during ALS in cardiac arrest presenting as PEA are related to prognosis. An increase in heart rate was observed in the last 3-6 min before ROSC was obtained.

Does the choice of definition for defibrillation and CPR success impact the predictability of ventricular fibrillation waveform analysis?

BACKGROUND

Quantitative analysis of ventricular fibrillation (VF), such as amplitude spectral area (AMSA), predicts shock outcomes. However, there is no uniform definition of shock/cardiopulmonary resuscitation (CPR) success in out-of-hospital cardiac arrest (OHCA). The objective of this study is to investigate post-shock rhythm variations and the impact of shock/CPR success definition on the predictability of AMSA.

METHODS

A total of 554 shocks from 257 OHCA patients with VF as initial rhythm were analyzed. Post-shock rhythms were analyzed every 5s up to 120s and annotated as VF, asystole (AS) and organized rhythm (OR) at serial time intervals. Three shock/CPR success definitions were used to evaluate the predictability of AMSA: (1) termination of VF (ToVF); (2) return of organized electrical activity (ROEA); (3) return of potentially perfusing rhythm (RPPR).

RESULTS

Rhythm changes occurred after 54.5% (N=302) of shocks and 85.8% (N=259) of them occurred within 60s after shock delivery. The observed post-shock rhythm changes were (1) from AS to VF (24.9%), (2) from OR to VF (16.1%), and (3) from AS to OR (12.1%). The area under the receiver operating characteristic curve (AUC) for AMSA as a predictor of shock/CPR success reached its maximum 60s post-shock. The AUC was 0.646 for ToVF, 0.782 for ROEA, and 0.835 for RPPR (p<0.001) respectively.

CONCLUSIONS

Post-shock rhythm is unstable in the first minute after the shock. The predictability of AMSA varies depending on the definition of shock/CPR success and performs best with the return of potentially perfusing rhythm endpoint for OHCA.

Impact of Modified Treatment in Echocardiographically Confirmed Pseudo-Pulseless Electrical Activity in Out-of-Hospital Cardiac Arrest Patients with Constant End-Tidal Carbon Dioxide Pressure during Compression Pauses

This study evaluated the ability of focused echocardiography (FE) and capnography to differentiate between pulseless electrical activity (PEA) and pseudo-PEA in out-of-hospital cardiac arrest, and the potential survival benefits with modified treatment. In PEA patients with stable end-tidal carbon dioxide pressure ( PetCO2) during the compression pause and concomitant FE showing cardiac kinetic activity, the compression pause was prolonged for 15 s and an additional 20 IU vasopressin was administered. If pulselessness persisted, compressions were continued. Fifteen of the 16 patients studied (94%) achieved restoration of spontaneous circulation (ROSC); eight patients (50%) attained a good neurological outcome (Cerebral Performance Category 1–2). In an historical PEA group with stable PetCO2 values ( n = 48), ROSC was achieved in 26 patients (54%); four patients (8%) attained Cerebral Performance Category 1–2. Echocardiographical verification of the pseudo-PEA state enabled additional vasopressor treatment and cessation of chest compressions, and was associated with significantly higher rates of ROSC, survival to discharge and good neurological outcome.