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Background: Continuous positive airway pressure (CPAP) is considered the gold standard therapy for Obstructive Sleep Apnea (OSA); however, many side effects, such as uncomfortable high titration pressure (TP) and mouth dryness, are associated with this treatment. This work proposes using pressure oscillations superimposed on a mean pressure to modulate the upper airways, reduce TP, and stimulate the salivary glands to reduce mouth dryness.

Methods: Two nonconsecutive overnight randomized controlled clinical trials were designed, one with a standard CPAP setup but reduced TP and the other by adding superimposed pressure oscillations (SIPO) to the reduced TP CPAP setup. 33 OSA patients who usually received CPAP treatment with predetermined TP settings participated in the two trials. Complete polysomnography was performed for sleep and patient assessments. However, a spitting technique protocol was used on 15 randomly selected patients from the same group to investigate the effect of SIPO on mouth dryness. These trials are registered under ACTRN12622001518752.

Results: The apnea-hypopnea index (AHI) was significantly reduced from 25.08 ± 2.32 to 17.56 ± 2.11 (p = 0.020*) with SIPO, indicating a 29.95% reduction in AHI and a decrease in breathing obstructions during enhanced therapy. Additionally, SIPO significantly decreased the oxygen desaturation index (ODI) (p = 0.002), maintaining the blood oxygen level within the normal range during the trials. ODI≥3 decreased significantly by 38.04% with SIPO. Saliva test results demonstrated that SIPO significantly increased saliva volume by 23.13% in non-stimulation and by 39.09% during stimulation compared to the CPAP trial.

Conclusions: This work demonstrates that SIPO reduces the TP to 70% of its standard clinical setting and stimulates salivary secretion to reduce mouth dryness. Further, significant improvements in AHI, respiratory arousal index (RAI), Arousal index (AI), and sleep efficiency (SE) are observed. This work is proof of concept, and further trials should be undertaken to generalize the proposed technique.