Empirical mode decomposition approach to the estimation of cardiac baroreflex sensitivity in patients undergoing coronary artery bypass graft surgery

Cardiac baroreflex sensitivity (BRS) as assessed from spontaneous variability of heart period (HP) and systolic arterial pressure (SAP) is reduced during general anesthesia. Patients undergoing coronary artery bypass graft (CABG) surgery are characterized by a low BRS even before general anesthesia. These observations provide the basis of the difficulty in detecting the BRS reduction after the induction of general anesthesia in CABG patients. Empirical mode decomposition (EMD) is a technique decomposing the series into oscillatory modes at different time scales. We propose an EMD-based approach to the BRS estimate in 34 patients undergoing CABG. Results showed that the EMD-based method was not able to detect the BRS reduction in CABG patients after the induction of general anesthesia. The negative result was interpreted as a consequence of the inability of EMD-based method to account for HP-SAP causality.