Vital signs? There's an app for that

Is there truly a smart phone app for everything? Now, you can even use your phone to monitor your heath. Researchers at Worcester Polytechnic Institute (WPI) have recently published a study in IEEE: Transactions on Biomedical Engineering that details the development of a smart phone application that measures heart rate, heart rhythm, respiration rate and blood oxygen saturation. The application is easily adaptable to any smart phone with a camera.

An application already exists on the Android Market that uses light to take heart rate measurements. However, the researchers at WPI felt that it could have gone even farther, and that the potential to measure other vital signs had not been fully explored. They believe that there is a need for a low-cost and convenient way to be able to check your own health.

The app requires no more technology than what is already present in most phones; users simply press their finger against the built-in camera and let the light from the camera penetrate the skin. The light reflects off blood in the finger, and the color of the light is recorded. Changes in the color of the reflected light signify changes in vital signs.

The application was tested for accuracy by volunteers at WPI who attached themselves to the monitoring devices in use at most hospitals while simultaneously pressing their fingers on the cameras of Motorola Droid phones that had been fitted with the application. The volunteers then went through breathing exercises as their vital signs were monitored. The researchers tested to see if they could accurately detect heart rate and respiration rate, and if they could measure breathing rate and oxygen saturation in the blood.

They found that they could estimate respiration rate accurately. Also, they could measure oxygen saturation just as accurately as a pulse-oximeter could. In general, comparisons of the data revealed that the app was just as accurate as the traditional monitoring devices that were used, namely respiration belts, ECGs and pulse-oximeters.

The team that developed this technology was led by Ki Chon, a professor and the head of the biomedical engineering department of WPI. The algorithm used to measure respiratory rate was adapted from one previously developed by Chon, an expert in the field of signal processing, for use with a pulse-oximeter. Signal processing is a field of study in which signals of different forms, such as sounds or images, are collected and have operations performed on them.

The researchers believe that their technology could allow people to develop a database of their normal vital signs, which could lead to a faster detection of disease. This application could also be used to relay information to health care professionals.

A specific example is that the app could potentially detect atrial fibrillation, which is an irregular heart rate. This is a serious condition that can require rapid emergency treatment. A preliminary clinical study has already been started at the University of Massachusetts Medical School, using the app to detect atrial fibrillation.

The researchers also want to expand their technology for use on tablet devices that are equipped with a camera. The technology could also be used to detect signs of blood loss and of nervous system disorders.