Power spectrum analysis of heart rate variability signal in the diagnosis of diabetic neuropathy

A clinical test based on the cross-spectral analysis of heart-rate variability (HRV obtained from ECG) and respiration is proposed for the assessment of autonomic diabetic neuropathy. The analysis was performed by means of an autoregressive model in bivariate form, and autospectra, cross spectra, and squared coherence functions were evaluated. Spectral parameters and, in particular, the power of the HRV signal which is coherent and which is not coherent with respiration are considered during different physiological conditions. In a first step, a group of 20 normal subjects underwent this test and ranges of normality were obtained for each parameter. In a second step, diabetic patients were analyzed and the obtained values of the spectral parameters were compared with the normality ranges. The proposed test recognizes patients with neuropathy and gives an earlier diagnosis of a compromission of the autonomic nervous system