How is split-night polysomnography (PSG) used in the diagnosis of obstructive sleep apnea (OSA)?

Updated: Sep 15, 2020
  • Author: Himanshu Wickramasinghe, MD, MBBS; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Patients with a respiratory disturbance index (RDI) higher than 40 during the first 2 hours of diagnostic PSG should undergo a split-night PSG study. The final portion of the study is used for titrating the continuous positive airway pressure (CPAP) device. Split-night studies may be considered for patients with an RDI of 20-40, as based on clinical observations (eg, prolonged obstructive events, marked oxygen desaturation). A minimum of 3 hours of sleep is preferred to adequately titrate the CPAP device after this treatment is started.

Split-night studies require recording and analysis of the same parameters as those evaluated in standard diagnostic PSG. A single split-night study may not permit adequate titration of CPAP therapy. If treatment does not control symptoms, additional full-night CPAP titration may be required.

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