Digital Health Innovation: Handheld Device for Rapid Assessment of Vital Signs

A small trial of a portable device that can rapidly read a patient's vital signs shows it performs well compared with standard hospital monitors. The hand-held, battery-powered device - called MouthLab - is the invention of biomedical engineers at Johns Hopkins University School of Medicine in Baltimore, MD. The device, which picks up vital signs from the patient's lips and fingertips, could replace the cumbersome and restrictive equipment currently used in hospitals.


They say it will also collect more data than that gathered in a typical rapid medical assessment in an ambulance, emergency room, doctor's surgery or patient's home. A paper in the Annals of Biomedical Engineering describes a trial that assessed how well a MouthLab prototype performed against standard hospital monitors in 52 volunteers.

The trial tested the device's ability to measure heart rate, blood pressure, temperature, breathing rate and blood oxygen. It also assessed the device's ability to take a basic electrocardiogram.

The results show that the device compared well with vital signs measured by the hospital equipment. First author and lead engineer Gene Fridman, assistant professor of biomedical engineering and otolaryngology-head and neck surgery, says they envisage the device being a sort of "check- engine" light for humans, and: "It can be used by people without special training at home or in the field."

The team expects the device may be able to spot early signs of heart attack and other medical emergencies. And when the vital signs are good, then it should reduce unnecessary ambulance trips and emergency room visits.

Because the device has a sensor that goes in the mouth, the developers also plan to enlarge its scope to detect blood, saliva and breathe markers of potentially serious medical conditions.

Prof. Fridman explains:"We envision the detection of a wide range of disorders, from blood glucose levels for diabetics, to kidney failure, to oral, lung and breast cancers."

The device has a small, flexible mouthpiece like the one a scuba diver uses. This contains sensors for temperature and blood volume. The mouthpiece connects to a hand-held unit about the size of a telephone receiver.

Pulse and oxygen levels are measured via a thumb pad on the hand-held unit. Other sensors can measure breathing rate from the nose and mouth. The device also has three ECG electrodes - one in the thumb pad and two in the mouthpiece (one for the upper lip, the other for the lower lip).

The trial shows the thumb and lip ECG readings are comparable to those obtained from chest and ankle electrodes used for basic ECGs in many ambulances and clinics. The device incorporates a novel way of measuring blood pressure - it uses the ECG signals. When these show the heart is contracting, the device optically measures changes in the volume of blood reaching the thumb and upper lip.

The ECG-derived readings are converted into systolic and diastolic pressures. The trial shows these measures match those taken with standard, arm-squeezing cuffs. All readings are sent wirelessly to a nearby laptop that can show the results in real-time graphs.

The next model will not need a laptop, says Prof. Fridman, who envisages patients sending their results via their cellphones and an app that lets doctors add the readings to patients' medical records. He concludes: "Our final version will be smaller, more ergonomic, more user-friendly and faster. Our goal is to obtain all vital signs in under 10 seconds."