Experience in using split-day studies for suspected obstructive sleep apnea syndrome.

Background: Because in many locations the demand for sleep studies exceeds resources, we evaluated the utility of split-day in-laboratory studies (SDS) in highly selected patients.

Methods: We studied 100 eligible cases: 68 males (age 48.6+/-1.3 [standard error, se] years, body mass index (BMI): 32.6+/-0.8 kg/m(2)) and 32 females (age 50.9+/-2.4 years, BMI: 36.3+/-1.3 kg/m(2)) with severe subjective sleepiness (Epworth sleepiness scale: ESS 16) and suspected obstructive sleep apnea syndrome (OSAS).

Results: There were 86 conclusive studies that yielded both a diagnosis and sufficient information for management (86.0%) and 14 inconclusive studies that did not yield sufficient information for management (14.0%). In six cases (6.0%) with an inconclusive study a diagnosis was made, however, no titration data was obtained. Thus a definitive diagnosis was obtained in 92.0% of all cases. Those with inconclusive studies had additional assessment, and eight of them ultimately had a final diagnosis of a sleep breathing disorder (SBD) and six had another sleep disorder: four had narcolepsy, one had a movement disorder, one had sleep deprivation. Thus there were six patients (6.0%) in whom SDS yielded only an SBD diagnosis but there was insufficient data for titration; two patients (2.0%) who ultimately had severe OSAS who were not diagnosed on SDS.

Conclusions: SDS was found to be useful in the evaluation and treatment of highly selected patients with severe daytime sleepiness (ESS 16) and suspected OSAS.