A computer-aided biofeedback system for individual rehabilitation in children following heart operations

Objective: Aim of the study was to create a computer “game”, that is controlled by motion and regulated depending on the heart rate of the user for postoperative rehabilitation of children after heart surgery.

Methods: Two EZ320 Chronos Watches (Texas Instruments) with integrated acceleration sensors that transmit the sensor signal via Bluetooth where used to monitor the motion of the user. Heart rate was registered using a modified ChestBelt from Polar. A computer program was created using a C# engine. The “game” consisted of a surface representing a bird with a virtual landscape. The goal of this game is to fly the bird over different obstacles and collect treasures. To move the wings and therefore control the direction of the bird, the user has to move the arms. Dependent on the motion of the arms and the calculated workload and the measured heart rate, the bird moves through the landscape. A regulating mechanism is built in, to facilitate, that the user stays in an area of heart frequency that has been set up before. If the heart rate is too low, the user has to make more movements to get the bird flying. If the heart rate gets too high, less movement is necessary and the bird can take a rest on a cloud. If the heart rate is much too low or much too high the game is stopped, and an alarm is triggered.

Results: The Prototype was evaluated by 15 healthy users. The heart rate regulating algorithm fitted well with the desired value well. All of the users reached the target heart frequency. Quick movements of the arms imitating flying resulted often in easy pain in the shoulder.

Conclusions: The prototype implementation showed a basic potential for computer aided rehabilitation. Further investigations are needed and different ergonomic movements to meet the needs of the young patients.