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Keeping tabs on patients more effectively

One of the most time-consuming demands of any care environment is the need to check on the condition of patients. As well as stretching human resources, this can often result in patients being woken up unnecessarily. Emfit has developed a particularly elegant solution here, in the shape of highly sensitive, non-invasive sensors that can be used to detect patient movement and monitor a range of vital signs.

Emfit’s core technology is based on a ferroelectret film, incorporating thin electrically charged polymer layers separated by air voids, that produces a small electrical charge in response to changes in thickness. When the thickness of the film changes, the movement of the charged polymer layers generates an electromechanical signal.

Emfit has included this technology into a range of products, including systems for caring for people with dementia and epilepsy. One of its most promising new products is its Discreet Vitals Monitoring (DVM™) system, which can be used to measure and monitor a patient’s vital signs without the need for electrodes, leads, cuffs, or a cannula.

Communicating information rapidly

The DVM system consists of a digital signal control unit and a thin-film sensor placed beneath a patient’s mattress. Despite its distance from the patient, the extremely high sensitivity of the sensor enables it to detect the minute pressure changes caused by a patient’s heartbeat and respiratory movements. The control unit then uses specially developed algorithms to calculate heart and respiration rates, and detect movement as well.

Ethernet connectivity enables data to be collected from multiple beds.

A range of alarms can be generated, depending on whether the system detects the presence or absence of a patient in bed, or if the heart or respiratory rate exceeds or falls below a predefined threshold.

Thanks to twin channel output, the system can alert personnel both through a nurse call system but also if problems are encountered with saline or drug drips, for example. Ethernet connectivity means that a DVM installation can be hooked up to a LAN and collect data from multiple beds, and will soon be able to communicate alarms to cost-effective thin client monitors, which are rapidly becoming more widely used.

The system also has the potential to be used for long-term trend tracking, such as monitoring things like how a change in medication affects a person’s sleep activity or even BCG strength over longer periods of time.

More potential in the pipeline

The most obvious advantage of Emfit’s DVM technology is that it does not need to be in contact with a patient’s body, and can bring remote monitoring to more patients and cut the workload of nursing staff.

It is also considerably more rugged than the piezoelectric systems and strain gauge belts that are typically used to monitor patients’ respiration rates, and its sensors do not have to be changed so often for hygiene reasons. A single Emfit sensor can be used for up to five years, representing a potentially huge saving in financial terms.

Emfit is currently investigating a range of future applications for this technology outside hospitals and care facilities, including smart jail cells, where it could be used to monitor the health of suspects in custody.

The extremely high sensitivity of Emfit sensors enables them to detect the minute pressure changes caused by a patient’s heartbeat and respiratory movements, without the sensor and the patient needing to be in direct contact.

The benefits of Emfit’s DVM technology

  • Heart rate and respiration monitoring without physical contact
  • Bed-exit alarm reduces nurse workload and protects patients from falls and unmonitored wandering
  • Interfaces to existing nurse-call systems, both LAN and WLAN
  • Easy for staff to make beds and change sheets, as the sensor is placed under the mattress. This also protects sensors and helps ensure a long service life
  • Easy to move from one bed to another
  • Suitable for adults, children, and neonatals.

Emfit is a global leader in quasi-piezoelectric sensors. The company has pioneered the development and manufacture of patented ferroelectret sensors since 1990, and is the world’s leading manufacturer of these dynamic thin-film sensors today. Four families of sensors are available, in surface, ribbon, small area configurations, as well as Emfit film, an elastic permanently charged, electrode-free electret film.

In addition to the DVM system, Emfit also produces fall and wandering prevention products for automatically summoning help for people suffering from dementia, and epileptic seizure alarm systems. The latter monitor people with epilepsy when they are asleep, and feature the first technology that can detect both a person’s convulsive seizures and whether they leave their bed during the night using just one sensor – thanks to the system’s ability to distinguish normal movements from those associated with seizures.

> Heikki Räisänen
(Published in HighTech Finland 2008)