What is telemetry?
Telemetry is the science or process of making measurements from objects at a distance via transmission of information back to receiving equipment.
It is derived from the Greek words ‘tele’, meaning remote, and ‘metron’, meaning measure. Telemetry is used across a wide range of industries, including space science, agriculture, motor racing, meteorology and environmental monitoring.
The main benefit is an end-user’s ability to monitor the state of an object or environment while being physically removed from it. Early telemetry systems used wires to transmit information back to the monitoring station but, nowadays, telemetry data is usually relayed wirelessly using radio waves.
Telemetry in medicine
Telemetry has become an important tool in medicine, particularly in the field of cardiology, where it is used to monitor the electrical activity of a patient’s heart (known as the electrocardiogram or ECG). The first ‘portable’ cardiac telemetry device was created by Norman J Holter in 1947 and consisted of two heavy batteries and an ECG radio transmitter. Weighing 38kg, it had to be strapped on the back of the subject! Despite its size, the device successfully enabled the subject’s ECG to be recorded whilst they remained active, rather than lying supine in a bed.
This eventually led to the development of pocket-sized ‘Holter’ cardiac ECG monitors that are still in routine use today by physicians to detect and monitor cardiac arrhythmia during 24h ambulatory cardiac investigations. Data collected from a Holter monitor is stored internally on a memory card for off-line analysis, but more modern mobile cardiac devices now allow ECG data to be recorded and transmitted in real-time by wireless telemetry over the mobile network to a monitoring centre where it is reviewed for abnormalities by trained medical professionals.
Continuous remote monitoring allows the opportunity to provide immediate emergency treatment if required.
Telemetry in the development of new medicines
In the early 1990s, fully implantable telemetry devices for measuring biological signals in laboratory animals became commercially available and subsequently transformed certain biological research areas such as safety pharmacology and toxicology. Such scientific disciplines investigate the effects of potential new medicines on vital organ function to ensure potential new medicines in development are safe for further testing in human clinical trials. The miniature telemetry units used comprise sensors and transmitters which detect physiological signals of interest such as ECG, blood pressure, respiratory rate and EEG (electroencephalogram) and send them wirelessly to receivers. This system has many advantages over traditional techniques, most importantly allowing continuous recording of physiological signals whilst the animals are conscious and freely moving. Recordings are made without the need for any physical restraint, enabling stress-free data collection, improving the welfare of the animals, and eliminating a source of experimental artefact and variability.
Data can be measured around the clock and over several days, weeks or months. The ability to measure continuous physiological data results in more accurate, less variable estimations of the effects of a test drug and enables the detection of very small changes in vital organ function, which may have a pathophysiological impact. Telemetry facilitates ‘within-subject’ study designs where the same subject is used in both the test and control arms. This, in concert with the improved quality of data recorded, enables fewer subjects to be used, reducing overall animal usage in the development of new medicines.
At Vivonics we use telemetry routinely in early phase preclinical in vivo studies to help our clients assess safety, optimise molecules and select better candidates for further development.
Gawłowska J. Norman J. “Jeff” Holter (1914–1983). Cardiology Journal. 2009, Vol. 16, No. 4, pp. 386–387.
Kramer K, Kinter LB. Evaluation and applications of radiotelemetry in small laboratory animals. Physiol Genomics. 2003 May 13;13(3):197-205.