21 percent of adults in Austria are treated for high blood pressure, another 24 percent suffer from it without knowing it. Elevated blood pressure is usually asymptomatic at first, but only when it is very high does it manifest itself as headaches, dizziness or circulation problems. Early detection does not always require drug treatment. The Cardiovascular Diagnostics team led by pulse wave expert Siegfried Wassertheurer, Competence Unit Biomedical Systems at the Center for Health & Bioresources, has found a solution to this problem: A pulse wave measuring device in the form of a modern wearable that is connected to the smartphone via an app. The wearable is simply held in the hand and the app instructs the user to breathe in a controlled manner, effectively lowering blood pressure and providing real-time feedback to the user. Martin Bachler from the Cardiovascular Diagnostics Team has now proven its efficacy in a study, that has already been awarded by the German Hypertension League (Deutschen Hochdruckliga e.V.).
Guided slow breathing can lower blood pressure
It sounds simple: slow breathing can lower blood pressure. To effectively implement this, a trainer could help, or the newly developed Wearable. By holding the device, it can display the vital parameters live, providing direct feedback and guidance to further lower blood pressure.
The time it takes a blood pressure pulse to travel from the heart through the arteries to a specific location in the body is called the pulse arrival time (PAT). To date, no technology with continuous real-time biofeedback of PAT during controlled slow breathing exercises is publicly available.
The device uses electrocardiography (ECG) to determine heart activity and an optic finger-sensor to measure the pulse wave. Thus, the PAT for each individual heartbeat is calculated in real time and displayed to the patient on his smartphone or tablet. In addition, active breathing is guided by the device with animations on the same display.
In the study 30 patients with hypertension were examined, 11 women and 19 men, aged between 45 and 78 years. The Wearable supported the patients in 10-minute sessions with instructions to slow down their breathing rate and gave them direct feedback of their PAT. The normal breathing rate was approximately 14 breaths per minute. The exercise reduced breathing to about 5.4 breaths per minute.
More than 85% of the patients showed an increase in PAT and thus a decrease in blood pressure. The user-friendly system can therefore help patients to lower their blood pressure in a self-managed and app-based manner.
In order to investigate longer-term effects, the AIT system will be used in studies with several hundred subjects over the next few years and will be further developed in a follow-up project to not only assess the reduction in blood pressure, but also to measure absolute blood pressure.
This research project was financed by the province of Lower Austria with co-financing from the European Regional Development Fund the „Europäischen Fonds für regionale Entwicklung“ (EFRE) - project "smartPWA". / WST3-F-5030665/002-2017
Link to the study: https://iopscience.iop.org/article/10.1088/1361-6579/abb320
Martin Bachler explains the project in one minute: https://youtu.be/O7OKQX9YTpA
