Predicting continuous positive airway pressure from a modified split-night protocol in moderate to severe obstructive sleep apnea-hypopnea syndrome

Abstract

Background: Most split-night sleep (SNS) studies have enrolled Caucasian patients with moderate-to-severe obstructive sleep apnea-hypopnea syndrome (OSAHS), with different apnea-hypopnea index (AHI) criteria for diagnosis and successful CPAP titration from the standard full-night study (FNS). This study aimed to describe a shortened diagnostic SNS in the Taiwanese population using diagnostic and CPAP therapeutic criteria identical to the standard FNS, and to generate a predictive equation for effective CPAP (Peff) titration. Methods: A total of 418 patients with moderate-to-severe OSAHS were enrolled in this study. The duration of the diagnostic SNS was shortened to approximately 1-2 hours. The diagnostic accuracy and the success rate of CPAP titration in SNS were evaluated and a statistical model for Peff was built. The accuracy of the predictive equation was validated in another 127 patients. Results: Eighty-nine percent of patients with moderate-to-severe OSAHS diagnosed in the preceding FNS yielded the same grade of OSAHS in SNS. These reproducible patients were more severe, with 88% attaining successful CPAP titration in SNS. The predictive Peff=1.98+0.184 BMI+0.01 AHISNS +0.016 DISNS (R2=0.28, p<0.0001) where BMI was the body mass index and DI the desaturation index. The λ predictive Peff - Peff λ was within 2 cm H2O in 84% of the study group and 73% of the validation group. Conclusion: The modified split-night protocol and the predictive equation for CPAP can be useful in Taiwanese patients with moderate-to-severe OSAHS. Our findings may shorten the waiting time for polysomnography. © 2008 The Japanese Society of Internal Medicine.