EVALUATION OF THE STRESS ON AUTONOMIC NERVOUS SYSTEM OF PATIENTS DURING MECHANICAL CIRCULATORY SUPPORT

Abstract

Background: The power density values of high frequency (0.15 to 0.4 Hz) and low frequency (0.04 to 0.15 Hz) components of systemic arterial pressure (SAP) signals have been regarded as the function of autonomic nervous system(ANS). In this study, the power spectral analysis (PSA) of SAP was adopted for evaluation of the stress on ANS of patients during mechanical circulatory support. Methods: SAP signals were acquired every 2 hours at 100 Hz for 6 minitutes in patients during mechanical circulatory support (MCS). PSA was carried out, and trends of changes in the spectral components of SAP were observed in patients with MCS (IABP and/or PCPS; n=13) and without the support (n=10). Results: The normalized power spectral component in low frequency (LFAnorm) was depressed initially in all patients. The value increased gradually in all patients except 4 with MCS. Sustained low values in LFAnorm in the 4 patients were related to prolonged MCS, and 3 patients among them were expired consequently. On the contrary, the duration of MCS in 3 patients showing no LFAnorm depression in weaning from MCS was significantly shorter than that of patients weaned from MCS with LFAnorm depression. Conclusions: Depressed LFAnorm ofSAP signals represented marked stress on ANS and prolongation of the depression was related to poor outcome of patients. The depression in weaning from MCS also indicated the stress on ANS during the process. PSA of SAP offers a reasonable tool for evaluation of the stress on ANS and prediction of the prognosis of patients with circulatory assist devices.