September 2005

Deciding on a Split-Night Study
Oksana Shulzhenko, MD, FCCP, ABSM
Medical Director

Split-night polysomnogram (PSG) testing, typically applied to patients to rule out obstructive sleep apnea (OSA), has existed for quite some time. It allows for the initiation of nasal continuous positive airway pressure (NCPAP) titration to occur during the initial, first night of study in the sleep lab, thereby eliminating the need for a second night of testing.

Although there are pros and cons associated with split-night testing as compared to a two-night testing protocol, correctly performed split-night PSG testing is a reasonable and valid approach to reaching more patients in need of sleep disorders testing while maintaining outcomes comparable to those achieved with a two-night protocol.

Split-Night Criteria
The following criteria is in place at Midwest Center for Sleep Disorders in order to assure that the most appropriate testing protocol is applied:

A) Demonstration of severe sleep disordered breathing at a rate of 30 events per hour documented during a minimum of 2 hours diagnostic polysomnography. Events are not exclusively position or stage dependant.

B) Demonstration of severe sleep disordered breathing (an AHI of at least 20 events per hour), documented during a minimum of 2 hours diagnostic polysomnography, along with at least one of the following:

1. Repetitive, severe oxyhemoglobin desaturation to below 70%
2. Repetitive oxyhemoglobin desaturation without a return to baseline

3. Apnea and hypopnea events accompanied by a 3 second asystole, ventricular tachycardia (V-Tach), or other arrhythmia

A minimum of 3 hours for titration must be available when considering a split-night study to ensure adequate time for the titration.

To be considered an effective titration, CPAP/BiLevel must control respiratory events during REM and NREM sleep in the lateral and supine positions, including REM sleep with the patient in the SUPINE position.

Further Recommendations
Patients who are allowed an entire night to be titrated on
NCPAP clearly have the additional time and benefit to discover potential problems and issues while in the presence of sleep lab personnel who are able to intervene. In comparison, the entire titration phase of a splitnight test is usually no longer than three to four hours. In light of this, the two-night protocol may increase initial compliance to therapy.

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