In the last decade Nasal Continuous Positive Airway Pressure (NCPAP) has gained acceptance for the treatment of Obstructive Sleep Apnea Syndrome (OSAS). A second night polysomnography is usually required to establish the therapeutic NCPAP pressure.¹ This retrospective study examines the relationship between apnea index, % ideal body weight (IBW), and therapeutic NCPAP levels.

Methods

We retrospectively selected 60 subjects from our files. All 60 subjects were males with a mean age of 51 years, an apnea index >5 prior to NCPAP and an apnea index <5 following NCPAP therapy. We analyzed apnea index and % IBW as our variables using the linear regression technique.²

Results

The correlation coefficient of apnea index and NCPAPwas .71, illustrated by graph #1.

The correlation coefficient of % IBW and NCPAPwas .26, which is illustrated in graph #2.

Conclusion

Apnea index correlates well with therapeutic NCPAP pressure. % IBW is a poor predictor of therapeutic NCPAP pressure. This data suggests that apnea index may be a helpful variable when selecting NCPAP pressures imperically. A follow up study using apnea index to predict therapeutic pressure is currently under investigation.

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1 C.Iber, C.O’Brien, J.Schluter, S.Davies, J.Leatherman, M.Mahowald, Single Night Studies in Obstructive Sleep Apnea., Sleep 14(5):Oct.,1991

2 Demirozu, Hen, Gazeroglu, Chediak, Effective nasal continuous positive airway pressure cannot be predicted based on respiratory variables of a baseline polysomnography., Sleep Research 20:231, 1991