Heart Rate Variability Analysis During Weaning from Mechanical Ventilation: Models for Prediction of the Weaning Trial Outcome

This study estimates the activity of the autonomic cardiac control (ACC) in patients undergoing weaning from mechanical ventilation, aiming to predict the weaning outcome. ECG and AVEA ventilator data from 13 successfully and 14 unsuccessfully weaned patients were collected. Heart rate variability (HRV) profiles were estimated in non-sedated patients during 2 weaning phases: (1) PSV - pressure support ventilation at 12-25 cmH(2)O; (2) SBT - spontaneous breathing trial at 8 cmH(2)O. HRV indices in the time- and frequency-domain were analyzed on 5-min RR-interval episodes under stationary conditions during each weaning phase. Our model for prediction of the successful weaning outcome considers 3 basic mechanisms for adequate ACC response on the weaning cardio-respiratory stress: (1) preserved ACC ability to maintain physiological adaptation; (2) modulated ACC activity by the breathing model; (3) mostly neurohumoral regulation of the blood circulation. The successful group model exhibits reduced total activity (TP, SDNN) with increased sympathetic (VLF/TP, LF/HF>1) and reduced vagal tone (HF/TP, RMSSD, pNN50), the latter correlated to the respiratory rate and tidal volume. Deviations from this HRV model are indicative for weaning failure detected with accuracy 92.6% (PSV), 81.5% (SBT), 96.3% (SBT-PSV).