BACKGROUND:Obstructive Sleep Apnea Syndrome (OSAS) is of increasing importance because of its high prevalence and danger of morbidity to untreated patients. With the cost and inconvenience of doing polysomnography (PSG), oximetry has been proposed as a tool in the diagnosis of OSAS. The objective of this study is to correlate the Respiratory Disturbance Index (RDI) with oximetry parameters.
DESIGN: Cross-sectional Study
STUDY SETTING: St. Lukes Medical Center Comprehensive Sleep Disorders Center
MATERIALS AND METHODS: Patients referred to the Sleep Center for PSG with symptoms suggestive of OSAS were investigated. Their clinical features and questionnaire responses were reviewed. RDI was calculated for all the patients and were classified as mild, moderate, and severe. Oximetry parameters determined include mean lowest SaO2 (MLSAT), lowest oxygen saturation (LSAT), and mean oxygen saturation (MSAT).
RESULTS: Three hundred one patients were included. A total of 223 (74 percent) OSAS patients were identified of which 24 percent (54/223) had mild OSA, 10 percent (22/223) had moderate OSA and 66 percent (146/223) had severe OSA. Height, weight, body mass index (BMI) and neck circumference were significantly different between patients with and without OSAS at p0.05. Comparison of the MLSAT, LSAT, and MSAT in patients with and without OSA showed a significant difference at p0.05. There was likewise a significant difference (p30/hr had significant negative correlation with MLSAT (r=-0.441; p=0.000), LSAT (r=-0.247; p=0.003), and MSAT (r=-0.430; p=0.000).
CONCLUSION: Significant correlation of RDI with oximetry parameters is seen only in patients with RDI 30. Further, since a considerable overlap in terms of clinical data between patients with and without OSA is noted, the greatest value of oximetry in our study seems to be as a tool to rapidly recognize and prioritize OSAS patients for treatment.