Online patient monitoring

Dec 15 2005

Drivers know whether or not their cars are running properly by observing the dashboard. Physicians can check vital parameters such as the pulse even when their patients are at home. The data can be recorded with the wireless monitoring device VitaSENS.

The modern automobile relies on sensors to monitor the vehicle’s operating condition. Whether it’s the speed, RPM, open doors, oil pressure, coolant temperature or fuel level, the driver constantly receives information about the “health” and well-being of his car. Should he be unfortunate enough to land in the hospital himself, it is his own vital parameters that the attending physicians will need to check. Regularly measuring and monitoring vital signs like pulse, temperature or blood oxygen content can also be important in rehabilitation clinics, as part of post-therapy treatment at home, or during professional sports activities.

It was to meet this need that Fraunhofer researchers introduced the multi-sensory Body Area Network (BAN) four years ago. In the meantime, they have integrated a whole series of sensors in a single device and christened it VitaSENS. Optical sensors attached to the earlobe, finger or arm measure the blood oxygen saturation, heart rate and arterial pulse curve – the latter being the pulse wave generated by the heart muscle each time it contracts.

Three to four electrodes placed on the upper body provide an ECG. An optional position sensor determines whether the patient is in a standing or lying position. The speed at which this signal changes reveals whether the patient has fallen or merely decided to lie down. The respiratory sensor, especially useful in sleep research, can provide an indication of apnea by measuring the respiratory flow rate. Using the ZigBee or Bluetooth wireless communications standard with a range of between 10 and 100 meters, each sensor transmits its measurements to a base station without ensnaring the patient in cable spaghetti.

The base station analyzes the individual measurements, recognizes medically relevant results and when needed transmits them to the physician’s office, clinic or other treatment facility. One version of the VitaSENS sends the data directly to a mobile phone, which then relays the information in case of an emergency, thus ensuring maximum mobility.

“We’re currently working with two equipment manufacturers to convert our prototypes to series production,” says Christian Weigand of the Fraunhofer Institute for Integrated Circuits IIS. “It’s also important that we continue to make the components even smaller so that they are less of a burden on the patient.” Yet despite these demanding goals, the researchers must ensure that the process of measuring and transmitting the patient’s 'operating condition' remains reliable and error-free at all times.