Medicine was revolutionized in modern times by technologies that let doctors “see” inside their patients. It began in 1895 with X-Ray[i] pictures (X-Rays) that revealed skeletal structures, the presence of bone fractures and solid objects in the body. Improvements followed, but fundamentally new technologies and techniques took decades to emerge. Medical ultrasounds[ii] began in the early 1940s, Computed Axial Tomography (Cat Scans)[iii] were invented in the early 1970s and Magnetic Resonance Imaging (MRIs)[iv] were introduced in the late 1970s. These systems proved exceptionally useful in diagnostic work and reduced the need for more complex procedures, such as exploratory surgeries.
Consumer grade medical devices were slower to emerge, with some exceptions like clinical thermometers, which can be traced to the seventeenth century. Glucose meters designed for home use, for example, were only introduced in the early 1980s. Heart rate monitors designed primarily for athletes appeared in the late 1970s, with wireless versions following in the mid-1980s. The pace of innovation quickened over the past decade as new products designed around small sensors, integrated microprocessors and software entered the consumer market. These smart devices made it possible for medically untrained users to monitor their blood pressure, blood glucose, oxygen saturation and heart rate. The latest versions connect with smart phones and upload readings to the cloud, where they are processed by powerful algorithms that translate raw data into actionable information that most users can understand. These systems also enable doctors to closely monitor their patients’ physiological conditions and changes over time, as opposed to relying on less frequent measurements taken during office visits.
A related category of devices, activity-fitness monitors, similarly entered the market about ten years ago and quickly blurred the line between fitness and health. The early models such as the Nike+iPod Sports Kit introduced in 2006, only measured distance and pace. Today’s versions use GPS receivers and tiny accelerometers to count steps and measure course, distance, elevation and pace. Fitness monitors by themselves or in conjunction with other devices like chess-strap heart rate monitors put health data in greater context by contributing physical activity information such as number of steps taken, movement (intensity, velocity, distance and changes in altitude), exercise recovery and resting times. Many are designed to work with mobile applications that connect with smart scales to capture body weight and Body-Mass-Index (BMI) measurements, all of which are uploaded to the cloud.
One of the latest health technologies to enter the specialty consumer market is the disposable ingestible sensor pill. They are primarily used by elite athletes to dynamically capture internal body (core) temperature and wirelessly transmit readings to a connected device[v]. Future versions are expected to monitor other biological factors such as stomach acidity (pH) and heart rate. The next frontier in instrumenting the body may be implantable sensors that continuously monitor vital signs and other physiological functions over extended periods. The primary barriers to implantable sensors are costs and intrusive installation procedures involving minor surgery.
The most promising emerging technologies for dynamically visualizing internal body activity are based on measuring, stimulating and interpreting internal electrical signals. Interestingly, most of the theories and concepts behind these systems were conceived many decades ago. For example, Electrocardiography (ECGs and EKGs) was introduced in the early 1900s to measure the heart’s electric signals[vi]. Electromyography (EMG) was first clinically used in the 1980s to capture electrical signals generated by motor neurons to trigger muscle contractions[vii]. Electrical Impedance Myography (EIM) is a new technique for assessing muscle health by measuring the impedance of individual muscles and groups of muscles[viii]. EIM is based on a circuit model of cellular membrane and intracellular fluid proposed in the 1940s. What is revolutionary about these technologies is the application of specialized software to interpret electrical signals and translate them into images and dynamic video of the body’s internal muscular structures and physical activity. This is the exiting subject of the next post in this series.
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[i] X-Ray, Mayo Clinic, retrieved April 18, 2017, http://www.mayoclinic.org/tests-procedures/x-ray/basics/definition/prc-20009519
[ii] What is an ultrasound?, WebMD, retrieved April 18, 2017, http://www.webmd.com/a-to-z-guides/what-is-an-ultrasound#1
[iv] Magnetic Resonance Imaging, WebMD, retrieved April 18, 2017, http://www.webmd.com/a-to-z-guides/magnetic-resonance-imaging-mri#1
[vi] Electrocardiogram, WebMD, retrieved April 18, 2017, http://www.webmd.com/heart-disease/electrocardiogram#1
[vii] Electromyogram (EMG) and nerve conduction studies, WebMD, retrieved April 18, 2017, http://www.webmd.com/brain/electromyogram-emg-and-nerve-conduction-studies#1
[viii] Seward B. Rutkove, Electrical impedance myography: Background, current state, and future directions, Muscle & Nerve, September 18, 2009, http://onlinelibrary.wiley.com/doi/10.1002/mus.21362/abstract;jsessionid=936C56130724F6D50B577BFDB3CA0571.f03t01