Abstract
In order to establish a method for estimating sympathetic function, the coefficient of variation of resting wave amplitudes of plethysmography (CVWH), the ratio of amplitude of plethysmography in ice water immersion to the amplitude at rest (RWH) and the recovery rate of skin temperature after 5 minutes' ipsilateral ice water immersion to the resting skin temperature (T5) were studied.
Fifty diabetics ranging in age from 15 to 60 years (mean±SE=42.5±1.9), and 58 healthy controls ranging in age from 20 to 60 years (42.9±1.6) were subjected to this study.
In this study, plethysmographic waves were continuously recorded by photoplethysmometer PT300 (Fukuda), and the skin temperature was measured by digital thermometer Digimulti (Takara).
The study in healthy controls revealed that RWH was less influenced by aging or atherosclerosis than CVWH and T5. In diabetics, RWH and CVWH were lower than those in age-matched healthy controls. Diabetics with autonomic neuropathy had a significantly lower RWH than those without neuropathy.
More detailed relationships between RWH and the severity of autonomic disturbance were evaluated in 88 diabetics. There was a close relation between RWH and the autonomic neuropathy score sum of scored symptoms, orthostatic hypotension and CVR-R. The critical point for judging abnormal autonomic function was estimated at 30% of RWH of the controls.
We conclude that the measurement of RWH using digital plethysmography in a simple, reliable and quantitative method with which to assess autonomic function, particularly sympathetic function, in diabetic patients.
