Background

Obstructive sleep events cause overnight desaturations. As PAP therapy abolishes obstructive events, it is assumed that it should also correct these desaturations. Hence, performing NOxi after PAP initiation may have a limited impact on the management of obstructive sleep apnea (OSA). NOxi is not currently recommended. We aimed to assess the usefulness of NOxi in the management of OSA patients for whom NOxi was systematically performed following PAP initiation.

Methods

Data from a clinical monocentric hospital sleep-unit were retrieved. The outcomes of PAP treatment (clinical efficacy, apnea-hypopnea index [AHI], adherence and leaks downloaded from PAP devices) were collected. Two independent experts first assessed the outcome of OSA treatment as satisfactory or not, and later the NOxi result as satisfactory or not. NOxi was considered as useful when its results changed the initial expert assessment.

Results

We included 180 patients with baseline AHI= 45/h ± 21 and established on PAP for 7,5 ± 5 weeks. PAP initiation was considered satisfactory in 28% of cases. NOxi were abnormal in 51 (28 %) cases with 42 (82 %) showing a 3% desaturation index ? 10/h, 17 (33%) showing >10% time spent with a SpO2 <90% and 7 (13%) with both abnormalities. NOxi changed experts? satisfaction in 28% of cases. NOxi led to a change in PAP settings in 36 % of cases. Younden index defining the added value of NOxi was 0.06 with a sensitivity and a specificity of 30% and 76% to predict adequate PAP initiation. 

Conclusion

NOxi are frequently abnormal following PAP initiation but have limited usefulness with respect to the clinical management of OSA patients.