BLErelax

This app enables the recording and analysis of electrocardiography (ECG) and pulse wave data from custom-made smartPWA measuring devices via Bluetooth Low Energy (BLE), during a customizable relaxation exercise.

The app is divided into two main views. In the first view, a Bluetooth connection to the smartPWA measurement device is established. The second view provides a live display of the incoming data, the guidance for the slow breathing exercise, and the results of the exercises. It further can record data, PAT, and heart rates, share them, or automatically upload them to allow post-hoc analysis.

After starting the app, activated smartPWA devices within range are automatically listed. After the connection has been established, the app first displays the "Signal Check" view. Here the acquired ECG and pulse wave signals are displayed for visual control. If the signal quality is satisfactory, the relaxation exercise can be started.

With the help of the relaxation exercise, the user can try to slow down the pulse wave transit time. The relaxation exercise can be started by tapping the play button at the bottom of the screen. In the opened menu, the relaxation exercise can be customized. After it is started, the average value for the transit time is calculated over 40 seconds (visible in the yellow progress bar) as initial baseline value. During the relaxation exercise, the user follows the balloon shown with their breathing rhythm. As long as the balloon rises, the user breathes in. When it sinks, the user exhales. The exercise is followed by a cooling phase. During this phase, the users should try to continue to breathe calmly, without being guided by the balloon going up and down. After the cooling down phase is completed, the results (the pulse arrival time and heart rate) is visible in the “Results” tab.