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Study Objective:

Prior studies have demonstrated reduced inflammation after chronic use of CPAP therapy. This may lead to reduced pressures over time as the upper airway becomes more compliant. We sought to determine if there was a reduction in 90th percentile pressure requirements in patients on Auto PAP for OSA.


A retrospective chart review of 988 patients who underwent a sleep study at our sleep center was performed. Those with moderate to severe sleep apnea who were prescribed and compliant with Respironics Auto PAP were included, yielding a total of 46 patients for analysis. All statistical analysis analyses were performed using in SAS version 9.3.


Mean age of patients was 57.20 years and majority was male. Mean baseline AHI was 43.10. Mean follow up interval was 9.99 months. There was a trend towards decrease in pressure requirements over time, with a mean change of 0.46 cmH20 which was not significant. Patients with a baseline AHI ≥ 50 had a greater decrease in pressure requirements upon follow-up compared to those with an AHI


Our study demonstrated that 90th percentile pressure decreased over time with continuous use of Auto CPAP in patients with severe OSA (AHI >50) and in patients who lost weight.


Study Rationale: Few previous studies have shown that chronic CPAP use may be lead to reduced upper airway inflammation and edema. We hypothesized that this may lead to reduced pressure requirements over time as the upper airway becomes more compliant. However, there have been no studies that have studied change in pressure requirements with Auto PAP treatment in patients not undergoing bariatric surgery.


There was no significant change in pressure requirements for patients with moderate to severe OSA treated with Auto PAP, after a mean follow up interval of 10 months. On subgroup analysis, patients with a baseline AHI ≥ 50 (severe OSA) had a greater decrease in pressure compared to those with an AHI(non-severe OSA), potentially because they tend to lose weight on Auto CPAP while those with AHIOSA.