Prompt prediction of successful defibrillation from 1-s ventricular fibrillation waveform in patients with out-of-hospital sudden cardiac arrest.

PURPOSE: Ventricular fibrillation (VF) is a common cardiac arrest rhythm that can be terminated by electrical defibrillation. During cardiopulmonary resuscitation, there is a strong need for a prompt and reliable predictor of successful defibrillation because myocardial damage can result from repeated futile defibrillation attempts. Continuous wavelet transform (CWT) provides excellent time and frequency resolution of signals. The purpose of this study was to evaluate whether features based on CWT could predict successful defibrillation. METHODS: VF electrocardiogram (ECG) waveforms stored in ambulance-located defibrillators were collected. Predefibrillation waveforms were divided into 1.0- or 5.12-s VF waveforms. Indices in frequency domain or nonlinear analysis were calculated on the 5.12-s waveform. Simultaneously, CWT was performed on the 1.0-s waveform, and total low-band (1-3 Hz), mid-band (3-10 Hz), and high-band (10-32 Hz) energy were calculated. RESULTS: In 152 patients with out-of-hospital cardiac arrest, a total of 233 ECG predefibrillation recordings, consisting of 164 unsuccessful and 69 successful episodes, were analyzed. Indices of frequency domain analysis (peak frequency, centroid frequency, and amplitude spectral area), nonlinear analysis (approximate entropy and Hurst exponent, detrended fluctuation analysis), and CWT analysis (mid-band and high-band energy) were significantly different between unsuccessful and successful episodes (P < 0.01 for all). However, logistic regression analysis showed that centroid frequency and total mid-band energy were effective predictors (P < 0.01 for both). CONCLUSIONS: Energy spectrum analysis based on CWT as short as a 1.0-s VF ECG waveform enables prompt and reliable prediction of successful defibrillation.

Does central venous pressure or pulmonary capillary wedge pressure reflect the status of circulating blood volume in patients after extended transthoracic esophagectomy?

PURPOSE: We investigated whether central venous pressure (CVP) or pulmonary capillary wedge pressure (PCWP) can accurately reflect the status of circulating blood volume (CBV) during the perioperative period in adult patients after extended transthoracic esophagectomy. METHODS: In 16 adult patients undergoing esophagectomy, simultaneous measurements of CVP, PCWP, and CBV were made at the following seven points: baseline (before surgery) and at 0, 12, 24, 36, 48, and 60 h after admission to the intensive care unit (ICU). CBV was estimated at the bedside with a pulse-dye densitometry method using indocyanine green. The relationship between CBV and these filling pressures was analyzed by linear regression. RESULTS: A total of 122 paired observations were made. The mean value of CBV decreased by approximately -20% at admission to the ICU and increased by approximately 24% of baseline at 48 h after surgery. The time course of CVP and PCWP was similar to that of CBV: both decreased at admission to the ICU, then gradually increased, and peaked at 48 h after surgery. However, both pressures remained within normal ranges, and the actual changes from baseline were small. There was no significant relationship between CBV and CVP (r = 0.17, P = 0.07), and between CBV and PCWP (r = 0.03, P = 0.78). CONCLUSION: Neither CVP nor PCWP accurately reflected the status of CBV in adult patients after extended transthoracic esophagectomy.