- Design
- Randomised physiological and home study
- Population
- 29 adults with severe obstructive sleep apnoea on nasal CPAP
- Primary outcome
- Upper airway patency, titrated pressure and residual AHI with and without expiratory pressure alleviation
- Effect
- Titrated pressure 11.4 vs 9.2 cmH2O; residual AHI 3.7 vs 1.3/h on fixed CPAP
Expiratory pressure alleviation (EPA) lowers CPAP pressure during breathing out for comfort. This randomised study tested whether it compromises the upper airway in 29 adults with severe obstructive sleep apnoea (mean BMI 37, median AHI 58).
With EPA on, peak inspiratory flow during flow limitation fell (0.38 to 0.19 L/s, as reported), the manually titrated pressure needed was higher (11.4 vs 9.2 cmH2O), and residual AHI was higher on both fixed CPAP (3.7 vs 1.3 events/h) and auto-CPAP (1.4 vs 0.8 events/h). Adherence was about seven hours a night either way.
The study was small, and residual AHI stayed low in absolute terms. But EPA did not buy adherence, and it made the airway less stable, which matters most in severe disease.
- Consider leaving expiratory pressure alleviation (EPA) off by default in severe obstructive sleep apnoea.
- Re-check residual AHI on device downloads if EPA is switched on.
- Address discomfort first with mask fit, humidification and pressure ramp.
- Titrate with the EPA setting the patient will actually use at home.
Why it matters
A comfort setting built into CPAP devices may be undermining treatment in the patients who need it most.
Don't overread it
Residual AHI stayed low with EPA on; the clinical impact of the difference is untested.
The statistics, in plain English
The differences were statistically significant but small in absolute terms, and the study included only 29 patients. Adherence was the same, which removes the main reason to use the setting.
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