SYMPATHOINHIBITION IN CRITICAL ILLNESS DURING MECHANICAL CIRCULATORY SUPPORT

Abstract

In variability of systemic blood pressure, the power spectral component with high frequency (0.15 to 0.4 Hz) is usually regarded as a marker of the para-sympathetic activity, and the component with low frequency (0.04 to 0.15 Hz) has been related to the sympathetic activity. Purpose: To evaluate the applicability of power spectral analysis of systemic blood pressure in estimating the state of patients after cardiac surgery. Methods: Hemodynamic data were sampled every 2 hours at 100 Hz for 6 minitutes in patients undergone cardiac surgery. Power spectral analysis of systemic arterial pressure signals was carried out. A trend of changes in the spectral components of systemic arterial pressure were obsereved in the patients with mechanical circulatory support (group M; n=9) for low cardiac output syndrome (LOS) and in control patients without mechanical circulatory support (group N; n=9). Results: The power spectral component with low frequency have the tendency to increase in both groups except 3 patients in group M, and the increment of group M is behind that of group N. Sustained low values in the low frequency component of systemic arterial pressure signals in the 3 patients were related to prolonged mechanical circulatory support, and 2 patients among them were expired consequently. Conclusion: Recovery from the postoperative sympathoinhibitory state in patients with mechanical circulatory support significantly delayed comparing with that in patients without the support. Power spectral analysis of systemic arterial pressure provides a reasonable tool to evaluate the severity of patients' condition regarding the activity of autonomic nervous system which regulates the heart and blood vessels.