Abstract
To improve methods for evaluating autonomic functions in uremic patients undergoing hemodialysis, autonomic functions were studied in 12 diabetic patients, 14 non-diabetic patients and 12 normal controls. Blood pressure and heart rate responses while standing, during the Valsalva maneuver and while sustaining firm handgrip were measured, and the spectral analysis of beat-to-beat fluctuations in heart rate and microvibration, and peripheral blood flow analysis were made in all patients and controls.
The classical methods (measurement of blood pressure and heart rate responses) revealed that the dialyzed patients, especially the diabetic group, had autonomic dysfunction. However, the stimuli used in these tests such as holding the breath, standing, and gripping were aggravating to some patients and the degree of stimulus varied in each patient. Therefore, a nonaggravating, quantitative method to assess autonomic control must be established.
The spectral analysis of heart rate and microvibration, and peripheral blood flow analysis are cited as acceptable alternative methods for this purpose. In this study, however, the power spectrum of the heart rate using the maximum entropy method did not reveal any differences between dialyzed patients and controls. In the spectral analysis of microvibration using a fast Fourier transform, ation an abnormal pattern was observed in 25% of dialyzed patients. The peripheral blood flow measured by laser doppler flowmeter was reduced in patients receiving hemodialysis. However, the results did not correlate with results obtained by the classical methods, because the reduction of blood flow was also attributable to abnormalities of both nerve and vessel.
Therefore, it is concluded that the classical methods are still the most useful at the present time. Further development to analyze the heart rate interval or microvibration will be necessary to establish alternative useful methods for measuring autonomic function.
