Patients who remain in bed for long periods of time may develop pressure sores, which can in turn become potentially life-threatening chronic skin ulcers. A new sensor could help keep that from happening, using scattered light.
Currently being developed by a team at the University of South Australia, the sensor consists of a thin, inexpensive optical fiber, several of which are embedded in the surface of the bed's mattress.
The patient simply lies on those fibers, which is a less obtrusive setup than existing patient-monitoring devices that have to be worn on the body, and which presents fewer privacy issues than currently used patient-monitoring camera systems.
Light enters each fiber at one end, and exits at the other. By analyzing how that light is affected by its passage through the fiber – which is altered by the patient's movements – it's possible to tell if that person hasn't moved in too long of a long time. What's more, the patient's heart rate and rate of respiration can also be monitored, as they produce small but detectable body movements of their own.
"The optical fiber sensor we are using is designed so that when light travels from input to output it actually travels along many different paths inside the optical fiber," lead scientist Dr. Stephen Warren-Smith told us. "These paths are all slightly different in length, which leads to a complex light pattern at the output. The effect is due to optical interference, which is very similar to the speckle pattern you see when you shine a laser pointer on a wall. When the optical fiber is physically altered, such as bending and stretching, this speckle output changes quite rapidly and can therefore be used as a sensor."
It is hoped that once developed further, the technology could be used to alert nurses to patients who have remained in one position for too long, and need to be turned over. The sensors could also warn of deteriorating vital signs, without requiring patients to be hooked up to electrodes, cuffs or ventilators.
"Monitoring vital signs continuously, unobtrusively and cheaply via the mattress-embedded sensors is a far better solution for both patient and nurse," said Warren-Smith.
The research is described in a paper that was recently published in the Journal of Biomedical Optics.
Source: University of South Australia