Study objective: We compared the validity of a new
portable polysomnographic recorder against a laboratory-based
polysomnographic system from the same manufacturer.
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
Conclusion: Portable polysomnography is
a viable alternative to laboratory-based polysomnography and may be
improved further by better sensor attachment.
Abbreviations: AHI = apnea-hypopnea index;
ASDA = American Sleep Disorders Association; Att = attended;
EMG = electromyogram; EOG = electro-oculogram; MB = megabyte;
NS = not significant; OSA = obstructive sleep apnea;
PLM = periodic limb movement; PSGL = laboratory-based
polysomnograph; PSGP = portable polysomnography; REM = rapid eye
movement; Sao2 = arterial oxygen saturation;
TST = total sleep time; Unatt = unattended