gms | German Medical Science

Objective: Changes of vascular motility may exhibit an important facet of essential hypertension. However, measurements of vascular motility in humans are difficult to arrange routinely. In the present study we investigated vascular motility using digital volume photoplethysmography and a novel analysis of pulse waves.

Methods: The fingertip pulse waves were measured by the transmission of red and infrared light through the finger pulp using a Vitaguard VG3000 monitor (getemed, Teltow, Germany) with the sensor located at the third digit of the hand. For each pulse wave the mean value of the data points from 93 ms to 218 ms adjacent to the inflection point was calculated and designated reflective index. Mean values of the reflective index were averaged every 150 seconds. The reflective index was continuously measured throughout the night in a supine position, starting at 23:00 and ending at 06:00. The distribution of the reflective index during the night was measured in 21 patients with essential hypertension and 20 normotensive control subjects.

Results: Ice immersion significantly increased the reflective index by 14±6 (mean±SEM; n=5; p<0.05), whereas the administration of glyceryl trinitrate reduced the reflective index by 21±2 (n=11; p<0.01). At the start of sleeping the reflective index was not significantly different in patients with essential hypertension compared with normotensive control subjects (33.0±2.6; n=21; vs. 30.5±2.3; n=20; mean±SEM; p=0.60). The reflective index exhibited a characteristic nocturnal rhythmicity that could be described best by a damped oscillation. The amplitudes of the reflective index during the sleep were significantly more pronounced in patients with essential hypertension (from -3.1 to 2.7) compared with normotensive control subjects (from -1.8 to 1.7) indicating an increased vascular motility during sleep.

Conclusion: Photoplethysmographic measurements showed an increased vascular motility in essential hypertension.