The median frequency of the ECG during ventricular fibrillation: its use in an algorithm for estimating the duration of cardiac arrest

The dynamics of the frequency distribution in the power spectrum of the ECG recorded form 11 swine during ventricular fibrillation (VF) are characterized to determine whether enough information exists in this domain to estimate downtime (DT). The median frequency (FM) of the power spectrum is used to track the frequency distribution. The FM follows a dynamic repeatable course during the first 10 min of VF. Intersubject variability is small. The FM data of the 11 subjects are modeled with a set of first-order polynomial equations, and the algorithm is tested with data from an additional ten subjects. The algorithm predicts VF duration with an average error of -0.86 min; 71.5% of the predictions fell within the 95% confidence limits of the model. A signal processing tool is identified which may be useful in the prehospital treatment of VF.