PAP Adherence and Nasal Resistance. A Randomized Controlled Trial of CPAPflex versus CPAP in World Trade Center Responders.

Rationale: Continuous positive airway pressure (CPAP) adherence is often poor in obstructive sleep apnea (OSA) and may be influenced by nasal resistance. CPAP with a reduction of expiratory pressure (CPAPflex) may reduce discomfort in those with high nasal resistance and improve adherence in this subgroup.Objectives: To evaluate the association of positive airway pressure (PAP) treatment adherence to nasal resistance and examine if CPAPflex improves adherence over CPAP in subjects with high nasal resistance.Methods: A randomized double-blind crossover trial of 4 weeks each of CPAPflex versus CPAP in subjects exposed to World Trade Center dust with OSA stratified by nasal resistance, measured by 4-Phase Rhinomanometry.Results: Three hundred seventeen subjects with OSA (mean, apnea-hypopnea index with 4% O2 desaturation for hypopnea = 17 ± 14/h) were randomized. Overall, PAP adherence was poor, but adherence to CPAP (n = 239; mean hours per night [95% confidence interval (CI)]), 1.97 h (1.68 to 2.26) was greater than adherence to CPAPflex (n = 249; 1.65 h [1.39 to 1.91]; difference of 0.31 h [0.03; 0.6]; P < 0.05). Contrary to our hypothesis there was no correlation between nasal resistance and adherence to CPAP (r = 0.098; P = not significant) or CPAPflex (r = 0.056; P = not significant). There was no difference in adherence between CPAP and CPAPflex (mean Δ hours [95% CI]) in subjects with low resistance (0.33 h [-0.10 to 0.76]) or high nasal resistance (0.26 h [-0.14 to 0.66]). No significant differences were observed in any of the secondary outcomes between PAP modes.Conclusions: Contrary to expectations, our data do not show better adherence to CPAPflex than to CPAP in subjects with high or low nasal resistance and do show clinically insignificant better adherence overall with CPAP.Clinical trial registered with www.clinicaltrials.gov (NCT01753999).