Sleep Breath (2005) 9: 7–11 DOI 10.1007/s11325-005-0001-6 ORIGINAL ARTICLE Ahmed S. BaHammam Published online: 3 February 2005 # Springer-Verlag 2005 Signal failure of type 2 comprehensive unattended sleep studies in patients with suspected respiratory sleep disordered breathing Abstract We designed this study to assess the signal failure and sensor loss of unattended type 2 compre- hensive polysomnography (PSG) and compared that with in-lab attended PSG. Type 2 PSG was performed for 41 patients. The signal failure was estimated and compared to the signal failure in 60 patients for the in-lab PSGs. The signal failure in each individual electroencephalographic (EEG) channel, complete EEG sig- nals, electro-oculography (EOG), naso–oral flow, and thoracic belt were significantly greater in the unattended sleep studies. The failure rate for the different signals ranged from 0.128 min in electrocardiography (EKG) to 67.36 min in the thoracic belt signal. However, that did not affect the success rate of the studies. Acceptable scorable data was available in 97% of the performed unattended PSGs. Un- attended type 2 sleep studies can be performed for clinical use in the evaluation of sleep disordered breathing with low signal failure and sensor loss if the proper hook-up procedure was followed. Keywords Unattended . Sleep studies . Sleep apnea . Signal failure . Sensor . Type 2 polysomnography Introduction Sleep disordered breathing (SDB) is a relatively common problem [1]. The standard approach to diagnosing SDB is in-lab, technician-attended polysomnography (PSG). How- ever, proper in-lab PSG is not readily available to all in- stitutes, which results in improper patient evaluation and long waiting lists for patients needing diagnostic sleep study. The availability of the needed diagnostic equipment is one obstacle; however, in my view, the main obstacle facing practicing doctors in developing countries is the availability of an adequate number of trained sleep tech- nologists who can run the service in the sleep disorder cen- ters (SDCs) on a full-time basis. As a result, some practicing doctors relied on their clinical judgment for diagnosing SDB and adopted the practice of continuous positive airway pressure (CPAP) titration as an in-patient procedure under pulse oximetry monitoring and thereby prescribed CPAP without proper evaluation [2]. To help solve the problem of the availability of proper SDCs and an adequate number of trained technologists needed to run the service, portable monitoring (PM) has been proposed as an alternative to in-lab PSG. The proponents of PM suggest that it is less time- consuming and requires less expertise. The term “PM” cov- ers a wide range of devices that can record as much data as an attended in-lab PSG does or one single channel only, such as pulse oximetry. The American Sleep Disorders As- sociation (ASDA) classified sleep monitoring into four types [3]. Type 1 (standard in-lab attended PSG) was considered to be the reference standard to which other monitoring types are compared; type 2, comprehensive portable PSG, which incorporates a minimum of seven channels, including neuro- cardio-respiratory monitoring; type 3, which incorporates a minimum of four channels, including cardio-respiratory monitoring; and type 4, which incorporates one or two chan- nels, typically, oxygen saturation or air flow. A number of factors of can interfere with the signal of PSG recordings, such as the improper use of sensors, im- proper filtering of signals, and excessive movement of the studied subject. Unlike attended PSGs, trained personnel A. S. BaHammam (*) Sleep Disorders Center, Department of Medicine (38), College of Medicine, King Saud University, PO Box 2925 Riyadh, 11461, Saudi Arabia e-mail: ashammam@awalnet.net.sa, ashammam2@yahoo.com Tel.: +966-1-4671521 Fax: +966-1-4672558