Recent developments in communications technologies and associated computing and 
digital electronics now permit patient data, including routine vital signs, to 
be surveyed at a distance. Remote monitoring, or telemonitoring, can be regarded 
as a subdivision of telemedicine - the use of electronic and telecommunications 
technologies to provide and support health care when distance separates the 
participants. Depending on environment and purpose, the patient and the 
carer/system surveying, analysing or interpreting the data could be separated by 
as little as a few feet or be on different continents. Most telemonitoring 
systems will incorporate five components: data acquisition using an appropriate 
sensor; transmission of data from patient to clinician; integration of data with 
other data describing the state of the patient; synthesis of an appropriate 
action, or response or escalation in the care of the patient, and associated 
decision support; and storage of data. Telemonitoring is currently being used in 
community-based healthcare, at the scene of medical emergencies, by ambulance 
services and in hospitals. Current challenges in telemonitoring include: the 
lack of a full range of appropriate sensors, the bulk weight and size of the 
whole system or its components, battery life, available bandwidth, network 
coverage, and the costs of data transmission via public networks. Telemonitoring 
also has the ability to produce a mass of data - but this requires 
interpretation to be of clinical use and much necessary research work remains to 
be done.