Portable computerized polysomnography in attended and unattended settings

Study objective: We compared the validity of a new portable polysomnographic recorder against a laboratory-based polysomnographic system from the same manufacturer. Design and patients: Simultaneous, full polysomnographic recordings from the portable device (PSGP) and the laboratory-based system (PSGL) were obtained using separate sets of sensors on 20 patients referred for investigation of sleep apnea. Setting: After initial optimization of signals, the portable device was left unattended in 10 of the patients (to simulate home studies), while in the other 10 the signals were reviewed on a laptop computer screen and adjustments to electrode or sensor placement made as needed during the studies. Recordings were manually scored by a technologist blinded to the origin of the data. Measurements and results: The quality of signals was comparable between the PSGP and PSGL studies, apart from a slight decrease in respiratory signal quality during PSGP studies that led to reduced confidence in respiratory event scoring. SaO₂ signal loss was also greater in unattended PSGP. There was good agreement between PSGP and PSGL for sleep variables and the apnea- hypopnea index (r = 0.99). The periodic limb movement index was slightly lower during unattended PSGP. Blinded physician assessment of the records led to a recommendation for repeat studies due to poor signal quality in one (10%) attended and one (10%) unattended portable recording. There was no significant discordance between PSGP and PSGL in the final diagnostic formulations. Conclusion: Portable polysomnography is a viable alternative to laboratory-based polysomnography and may be improved further by better sensor attachment.