‘Tricorder’-style handheld MouthLab detects patients’ vital signs, rivaling hospital devices

Could be used by people without special training at home or in the field
August 25, 2015

Johns Hopkins’ MouthLab is intended to collect vital signs and ultimately to also obtain noninvasive biochemical and biophysical measurements from the saliva and breath and estimate blood-sugar level. A prototype can obtain vital signs and an electrocardiogram (ECG). (credit: Gene Y. Fridman et al./Annals of Biomedical Engineering)

Inspired by the Star Trek tricorder, engineers and physicians at the Johns Hopkins University School of Medicine have developed a hand-held, battery-powered device called MouthLab that quickly picks up vital signs from a patient’s lips and fingertip.

Updated versions of the prototype could replace the bulky, restrictive monitors now used to display patients’ vital signs in hospitals and actually gather more data than is typically collected during a medical assessment in an ambulance, emergency room, doctor’s office, or patient’s home.

The MouthLab prototype’s measurements of heart rate, blood pressure, temperature, breathing rate, and blood oxygen from 52 volunteers compared well with vital signs measured by standard hospital monitors. The device also takes a basic electrocardiogram. The study was published in the September issue of the Annals of Biomedical Engineering.

Early warning for non-doctors

“We see it as a ‘check-engine’ light for humans,” says the device’s lead engineer, Gene Fridman, Ph.D., an assistant professor of biomedical engineering and of otolaryngology–head and neck surgery at Johns Hopkins. “It can be used by people without special training at home or in the field.” He expects the device may be able to detect early signs of medical emergencies, such as heart attacks, or avoid unnecessary ambulance trips and emergency room visits when a patient’s vital signs are good.

MouthLab hand-held unit with one attached mouthpiece, and two other mouthpieces (of the 25 total produced) on the left panel. The right panel shows the MouthLab being used by a subject with the data from the MouthLab sensors and vital signs estimates displayed on the laptop in real time. (credit: Gene Y. Fridman et al./Annals of Biomedical Engineering)

Because it monitors vital signs by mouth, future versions of the device will be able to detect chemical cues in blood, saliva, and breath that act as markers for serious health conditions. “We envision the detection of a wide range of disorders,” Fridman says, “from blood glucose levels for diabetics, to kidney failure, to oral, lung and breast cancers.”

Comparable to hospital devices, more compact

The MouthLab prototype consists of a small, flexible mouthpiece like those that scuba divers use, connected to a hand-held unit about the size of a telephone receiver. The mouthpiece holds a temperature sensor and a blood-volume sensor. The thumb pad on the hand-held unit has a miniaturized pulse oximeter for measuring blood oxygen level— a smaller version of the finger-gripping device used in hospitals. Other sensors measure breathing from the nose and mouth.

MouthLab also has three electrodes for ECGs — one on the thumb pad, one on the upper lip of the mouthpiece and one on the lower lip. These work about as well as the chest and ankle electrodes used on basic ECG equipment in many ambulances or clinics, says Fridman.

That ECG signal is also the basis for MouthLab’s novel way of recording blood pressure. When the signal shows the heart is contracting, the device optically measures changes in the volume of blood reaching the thumb and upper lip. Unique software converts the blood flow data into systolic and diastolic pressure readings. The study found that MouthLab blood-pressure readings effectively match those taken with standard, arm-squeezing cuffs.

The hand unit relays data by Wi-Fi to a nearby laptop or smart device, where graphs display real-time results. The next generation of the device will display its own data readouts with no need for a laptop, says Fridman. Ultimately, he explains, patients will be able to send results to their doctors via cellphone, and an app will let physicians add them to patients’ electronic medical records.

A 3-D printer made the parts for the prototype, “which looks a lot like a hand-held taser,” Fridman says. “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.”

Abstract of MouthLab: A Tricorder Concept Optimized for Rapid Medical Assessment

The goal of rapid medical assessment (RMA) is to estimate the general health of a patient during an emergency room or a doctor’s office visit, or even while the patient is at home. Currently the devices used during RMA are typically “all-in-one” vital signs monitors. They require time, effort and expertise to attach various sensors to the body. A device optimized for RMA should instead require little effort or expertise to operate and be able to rapidly obtain and consolidate as much information as possible. MouthLab is a battery powered hand-held device intended to acquire and evaluate many measurements such as non-invasive blood sugar, saliva and respiratory biochemistry. Our initial prototype acquires standard vital signs: pulse rate (PR), breathing rate (BR), temperature (T), blood oxygen saturation (SpO2), blood pressure (BP), and a three-lead electrocardiogram. In our clinical study we tested the device performance against the measurements obtained with a standard patient monitor. 52 people participated in the study. The measurement errors were as follows: PR: −1.7 ± 3.5 BPM, BR: 0.4 ± 2.4 BPM, T: −0.4 ± 1.24 °F, SpO2: −0.6 ± 1.7%. BP systolic: −1.8 ± 12 mmHg, BP diastolic: 0.6 ± 8 mmHg. We have shown that RMA can be easily performed non-invasively by patients with no prior training.