DEVICE-GUIDED SLOW BREATHING WITH DIRECT BIOFEEDBACK OF PULSE WAVE VELOCITY – EFFECTS ON PULSE ARRIVAL TIME AND SELF-MEASURED BLOOD PRESSURE IN PATIENTS WITH HIGH NORMAL BLOOD PRESSURE

Objective: There is evidence that device guided slow breathing using biofeedback acutely reduces blood pressure (BP) and pulse wave velocity (i.e., increases pulse arrival time) from own prior studies and from the literature. The objectives of the study presented here were to test whether the results of changes observed in pulse arrival time in earlier studies are reproducible over one week and how changes in pulse wave velocity/pulse arrival time translate into absolute blood pressure changes. Design and method: Patients with a systolic BP 130–160 mmHg or treated essential hypertension (21 females / 23 males) were trained to perform repeated and unattended device guided slow breathing exercises over 5 days. A simple device was used to measure pulse arrival time by electrocardiography and photoplethysmography connected with a smartphone or tablet to provide biofeedback. Furthermore, they were skilled to perform a self-measurement of blood pressure before and after the breathing exercise using a validated upper-arm device. The mean of 3 consecutive self-measured readings was used before and after each breathing exercise. Results: Office BP at screening (Median [1.,3. Q]) was 137 [132,142] / 83 [79,87] mmHg. We observed an average increase of pulse arrival time (PAT) of 6ms (p < 0.05, SD 13ms) during the breathing exercise. This increase in PAT during slow breathing was accompagnied by a delayed arrival of the first pulse wave maximum and a prolonged ejection time. The increase in PAT was associated with a significant reduction of self-measured systolic blood pressure of 5 mmHg (p < 0.01, SD 8 mmHg) and beyond 6 mmHg (p < 0.01, SD 9 mmHg) of white coat effect. Data furthermore demonstrated that these changes were highly reproducible over one week Conclusions: The results of this work confirmed earlier findings from a pilot trial that a simple method for device guided slow breathing and biofeedback leads to favorable changes (increase) in pulse arrival time and systolic blood pressure (decrease) and therefore warrants future use of this method. Furthermore, the decrease in blood pressure was probably generated via vasodilation as shown by the wave shape parameters