Background:
Quantitative measures of the ventricular fibrillation (VF)
electrocardiogram (ECG) waveform can assess myocardial physiology and
predict cardiac arrest outcomes, making these measures a candidate to help
guide resuscitation. Chest compressions are typically paused for waveform
measure calculation, as compressions cause ECG artifact. However, such
pauses contradict resuscitation guideline recommendations to minimize CPR
interruptions. We evaluated a comprehensive group of VF measures with and
without ongoing compressions to determine their performance under both
conditions for predicting functionally-intact survival, the study’s
primary outcome.
Methods:
Five-second VF ECG segments were collected with and without chest
compressions prior to 2755 defibrillation shocks from 1151 out-of-hospital
cardiac arrest patients. Twenty-four individual measures and three
combination measures were implemented. Measures were optimized to predict
functionally-intact survival (Cerebral Performance Category score ≤
2) using 460 training cases, and their performance evaluated using 691
independent test cases.
Results:
Measures predicted functionally-intact survival on test data with an
area under the receiver operating characteristic curve (AUC) ranging from
0.56-0.75 (median=0.73) without chest compressions and from 0.53-0.75
(median=0.69) with compressions (p<0.001 for difference). Of all
measures evaluated, the support vector machine model ranked highest both
without chest compressions (AUC=0.75, 95% CI 0.73-0.78) and with
compressions (AUC=0.75, 95% CI 0.72-0.78) (p=0.75 for difference).
Conclusions:
VF waveform measures predict functionally-intact survival when
calculated during chest compressions, but prognostic performance is
generally reduced compared to compression-free analysis. However, support
vector machine models exhibited similar performance with and without
compressions while also achieving the highest AUC. Such machine learning
models may therefore offer means to guide resuscitation during uninterrupted
CPR.