Digital Medical Devices Fueling a Quiet Revolution in Health Care

Digital electronic medical instruments are proliferating widely and rapidly throughout the medical community. Take a look at the supplemental publication coming out with this issue of RTC that will cover this phenomenon—Medical Electronic Device Solutions.


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With all the attention that health care has gotten in the media in recent months, there appears to be a development that has largely escaped widespread notice. That is the migration of medical expertise into intelligent devices that are targeted not to replace trained physicians but to help spread their knowledge and services to a wider number of patients at specific levels of care.

It probably comes as no surprise that medical devices and equipment are going digital, from thermometers to stethoscopes to glucosometers to sophisticated MRI and medical imaging equipment; all have incorporated appropriate levels of digital capabilities. Take something as simple as a stethoscope. One model advertises up to 24 db amplification with noise filtering and three frequency modes: cardiac, diaphragm (for lung sounds) and an extended range of 15 to 1000 Hz. But the digitization and enhancement of the basic device functions is only part of the story.

When we get beyond simple functionality such as that of a thermometer or a stethoscope, we start to see the embedding of certain elements of medical expertise into the devices. When such devices make their measurements they produce data, which can partially be acted upon by the device itself such as flashing an LED if a blood sugar reading is out of range and/or connecting to the wider medical network for further analysis by qualified medical personnel. This opens up vast possibilities. Those possibilities involve the expansion of quality medical care to many more patients per doctor than is currently possible.

Steve Kennelly, Senior Manager of Microchip’s Medical Products Group, notes that, especially in handheld and portable medical devices, 8- and 16-bit microcontrollers play some very significant roles in making patient information available to the medical practitioner as well as to higher level devices and software that can perform additional analysis and make significant data available to the physician as a formatted presentation for more efficient analysis.

For example, an electrocardiograph (ECG) once consisted of a cluster of probes that were attached to the patient and then to channels on the ECG machine where they drove a set of pens that swept back and forth across the paper strip. The tests were administered by a medical technician and the results analyzed by the physician. The results (meaning the paper strip) were then stored in the patient’s record folder along with the doctor’s notes.

Implementing a digital ECG machine lets it make exactly the same measurements yet opens up a wealth of further possibilities (Figure 1). For one thing, there are now over 150 models of digital ECG machines available. Some have integrated LCD displays, some continue to produce paper strip charts, others have both and many have USB connections to transmit the ECG data to a PC. In fact, there are even a few that consist only of a hub containing the digital ECG functionality and the patient probes along with a USB connector to the PC. The PC then processes the data, produces the display, which can be stored digitally in the patient’s medical records and can sometimes even do some preliminary analysis to alert the physician. In fact, from some vendors there are even  Windows-based ECG analysis programs available that can compare sets of waveforms. Once on the PC, the data is, of course, also available for emailing to colleagues or specialists for consultation.

Figure 1
An electrocardiogram (ECG) measures the electrical activity of the heart. The resulting waveform can be directly displayed, recorded or analyzed in real time. Courtesy Microchip Technology.

Now the purpose of going into this level of detail about digital ECG machines is not simply to focus on them but to point out that similar developments are taking place across the wide spectrum of medical devices. These include large machines such as MRI and CT scanners down to blood pressure meters that can be used in the home. Yes, there are even limited heart data meters that a person can hold against the chest, place in a docking station attached to the home PC and transmit to the medical professional, where anomalies can be flagged instantly.

What is beginning to emerge, as we go from relatively simple devices like glucose meters, up to more sophisticated ones like a continuous positive air pressure (CPAP) device for treating sleep apnea, is more of the actual medical expertise being embedded into the device (Figure 2). The CPAP device is also used at home by the patient, but requires much more monitoring, control and intelligence to operate safely by adjusting to the patient’s breathing rate and adjusting temperature and humidity. And it also generates data that can be transmitted to a PC or a network.

Figure 2
A CPAP device provides therapy for obstructive sleep apnia. A small air compressor constantly adjusts to the user’s breathing pattern to maintain a constant pressure. Courtesy Microchip Technology.

A little higher up the hierarchy are devices that are somewhat beyond the patient’s ability to administer (the ECG is one) but do not require a physician’s attendance. These can be administered by a nurse practitioner, who can also use other devices that basically signal a “red light/green light” for conditions that are normal or that require a doctor’s attention. Designers of monitoring devices in a hospital room where the patient may not be constantly attended must pay very close attention to conditions that trigger alarms and the type of alarms they initiate to summon a nurse or doctor.

These levels of intelligence and the increasing ability of the patient to administer certain levels of care and to assign others to trained technicians will have a number of positive effects both medical and economic. For one thing, the physician can devote more of his or her time to seeing patients who require their level of expertise and can leave more routine monitoring and diagnostic duties to others, including the patient. It will also enable faster responses to ominous changes in condition when the data can be sent daily from the home rather than relying on periodic office visits to monitor conditions. This can result in better quality of life for elderly people who will be able to live at home longer.

There is, however, still much to be done and one of the obstacles is interoperability. For example, the ECG analysis software mentioned above appears to work with the data format generated by the machines made by that company. While this sort of thing is to be expected in a field that is growing this rapidly, it is a problem that must be solved to make the promise of telemedicine real.

Fortunately there is a major industry coalition of over 200 member companies called the Continua Alliance. On its Web site, Continua says, “Continua is dedicated to establishing a system of interoperable personal health solutions with the knowledge that extending those solutions into the home fosters independence, empowers individuals and provides opportunity for truly personalized health and wellness management.”

Continua selects pre-existing standards and specifications to form the basis of their certification program. Certified products receive a logo certifying interoperability with other certified products. The goal is to create a rich ecosystem that will, to quote Continua’s vision statement:


  • Empower individuals and patients to better manage their health by providing them with information regarding their fitness and health through personal medical devices and services.
  • Allow loved ones and professional care givers to more accurately monitor and coach chronic disease patients and elderly individuals living independently.
  • Enable medical and fitness device manufacturers to rapidly develop interoperable devices and services using industry developed connectivity standards.
  • Enable health care providers to offer better quality care through personalized health solutions assembled from a rich marketplace of interoperable health care devices and services.

Within this world of emerging intelligent medical devices, the embedded computer industry is playing a vital role. It will be the goal of Medical Electronic Device Solutions to present the latest technical information to assist medical OEMs and their vendors to identify opportunities and provide solutions.  

Continua Alliance
Beaverton, OR.
(503) 619-0867.