Evaluation of free-space propagation in hospital corridors

It has been proposed that increased usage of wireless communication (e.g. portable radio-frequency (RF) sources; wireless local area networks) should reduce health care costs and improve clinical-care efficiency. However, such increased usage must take place without increasing the risk of electromagnetic interference (EMI) to medical devices. Recommendations for electromagnetic compatibility (EMC) in health care environments have been described [e.g., ref 1]. Central to such recommendations is the requirement to manage RF sources and susceptible medical devices so that their interaction is minimized. It is usually proposed that this be done by specifying a Minimal Separation between RF sources of given power and medical devices of given immunity, assuming that free-space propagation is approximately valid. Alternately, it has been proposed that Zones be specified where approved RF sources and approved medical devices can operate. The latter approach would be required in areas where free-space propagation is invalid. We describe a preliminary study that assesses the validity of free-space propagation in hospital corridors, in order to evaluate whether minimal separations predicted by free-space propagation might safely permit EMC within corridors of a typical urban hospital.