Impairment of upper airway patency and CPAP effectiveness during obstructive sleep apnea treatment with expiratory pressure alleviation: a randomized study.

BACKGROUND: Expiratory pressure alleviation (EPA) algorithms have been incorporated into CPAP devices to reduce expiratory discomfort during treatment of obstructive sleep apnea (OSA). Since pharyngeal narrowing or collapse can occur during expiration, EPA may impair upper airway patency. RESEARCH QUESTION: Does EPA compromise upper airway patency and CPAP efficacy in patients with severe OSA? STUDY DESIGN AND METHODS: Adults with severe OSA using nasal CPAP were considered to participate. The study was conducted in four steps. Steps 1 and 2 were performed during a single overnight polysomnography (PSG) study. In step 1, peak inspiratory flow (PIF) was measured during inspiratory flow limitation with and without EPA. In step 2, CPAP titration was performed in randomized order with and without EPA. Steps 3 and 4 were conducted at home. Residual AHI and adherence were compared with and without EPA activation during fixed (Step 3) and auto-CPAP (Step 4). RESULTS: Twenty-nine subjects were studied (55% female; age 63±12 years; BMI 37±7 kg/m2; AHI 58 (39-83) events/h). EPA activation reduced PIF compared to without EPA (0.38 (0.34-0.42) vs 0.19 (0.15-0.23) L/s), respectively (P<0.001). Manually titrated CPAP level was higher with EPA than without EPA (11.40 ± 1.95 vs 9.17 ± 1.78 cmH2O), respectively (P<0.001). Residual AHI was higher with EPA than without EPA, during fixed (3.7 ± 2.2 vs 1.3 ± 0.6 events/h) and automatic CPAP (1.4 (0.6 - 2.1) vs (0.8 (0.5-1.8) events/h), respectively (P<0.05). No significant change in CPAP adherence was observed, during fixed (7.0 ± 0.8 vs 7.2 ± 1.0 hours) and automatic CPAP (7.0 ± 1.3 vs 6.9 ± 1.3 hours), with (P=0.497) and without (P=0.506) EPA, respectively. INTERPRETATION: EPA application compromised upper airway patency and required higher therapeutic CPAP than without EPA. EPA also impaired OSA control but did not impact CPAP adherence. CLINICAL TRIALS REGISTRY: NCT05219591.