Ambulatory telemetry systems

Ambulatory telemetry systems allow patients to move around the hospital while certain physiologic parameters are monitored. Traditionally, telemetry systems have used compact transmitters worn by the patient to take readings and transmit them to a central station. More recently, to expand telemetry's capabilities without adding excessive size and weight to the patient-worn transmitters, some suppliers have provided certain parameters using small wireless portable bedside monitors that are wheeled around on a roll stand by the patient. In this Evaluation, we judge the capabilities of 18 telemetry systems--14 that are intended for general telemetry use, 2 that are designed specifically for use in cardiac rehabilitation programs, and 2 that are marketed for both applications. For the general systems, we looked for the ability to provide electrocardiogram, pulse oximetry, and noninvasive blood pressure measurements as needed without making the patient transmitter too big and heavy for practical use. Cardiac rehab systems generally need to provide only ECG readings, so our ratings focus principally on patient comfort and the appropriateness of the systems' capabilities for this application. We also revisit some of the issues surrounding telemetry transmission techniques: Whether it's better to operate in the new Wireless Medical Telemetry Service (WMTS) frequencies than in the Industrial, Scientific, and Medical (ISM) bands, and whether bidirectional transmissions provide better telemetry capabilities than unidirectional ones.