Air leak is associated with poor adherence to autoPAP therapy

Abstract

Study objectives: To our knowledge, a systematic study of the effect of air leak on adherence to auto-titrating positive airway pressure (autoPAP) therapy has not been reported. We hypothesized that in patients with obstructive sleep apnea (OSA), greater levels of air leak were associated with poor adherence to autoPAP therapy.

Design: Retrospective cohort study

Setting: Academic Center

Participants: Ninety-six consecutive patients with high probability for OSA.

Interventions: N/A.

Measurements: Patients with OSA received 1 week of autoPAP therapy following which both adherence data and air leak information was downloaded from the device. Continuous positive airway pressure (CPAP) therapy was issued for a 5-week period with pressure determined by 90th percentile of that delivered during autoPAP therapy. Adequate adherence was defined as average usage > 4 h per night on all nights.

Results: Forty-three patients were adherent to autoPAP therapy (350 ± 67[SD] min/day), whereas 53 patients were not (122 ± 65 min/day; P < 0.0001). Air leak that was adjusted for pressure delivered was greater in non-adherent patients (7.0 ± 3.5 L/min/cm H(2)O) than that in adherent patients (4.9 ± 1.7 L/min/cm H(2)O; P < 0.0001). Greater residual respiratory events (measured as autoPAP-derived hypopnea index) and proportion of time spent at large leak levels were associated with non-adherence. Patients who were adherent to autoPAP therapy received higher average therapeutic pressures from the autoPAP device than non-adherent patients. Multivariate logistic regression revealed that higher levels of air leak were associated with non-adherence to autoPAP therapy (odds ratio 1.43; 95% CI, 1.03, 1.98; P = 0.03). Moreover, adherence to autoPAP therapy was strongly correlated with subsequent adherence to CPAP therapy (R(2) = 0.74; P < 0.0001).

Conclusion: Air leak was associated with poor adherence to autoPAP therapy. We speculate that air leak could be a potential target for future studies aimed at enhancing adherence to autoPAP therapy.

Keywords: Adherence; adherence; adult; artificial respiration; compliance; continuous positive airway pressure; obesity; obstructive sleep apnea; sleep apnea.

Figures

Figure 1

Average air leak levels adjusted for pressure level (Leakavg/Pavg) derived from the auto-titrating positive airway pressure (autoPAP) device downloaded at the end of one week of therapy are shown for adherent (solid column) and non-adherent patients (open columns; left panel). On the right panel, 90th percentile air leak levels adjusted for pressure level (Leak90/P90) derived from the autoPAP device download at the end of one week of therapy are shown for adherent (slope hatched column) and non-adherent patients (cross-hatched column). Average air leak levels adjusted for pressure in adherent patients were lower than those in non-adherent patients (P < 0.0001). Similarly, 90th percentile air leak levels adjusted for pressure were lower in adherent patients than in non-adherent patients (P = 0.001). § P < 0.01; L/min = liters per minute.

Figure 2

Receiver operating characteristics (ROC) for average leak adjusted for pressure (Leakavg/Pavg) in predicting non-adherence to auto-titrating positive airway pressure (autoPAP) therapy is shown as a blue line. ROC for 90th percentile leak adjusted for pressure (Leak90/P90) in predicting non-adherence to auto-titrating positive airway pressure (autoPAP) therapy is shown as a green line. ROC areas under the curve for both these measures are shown in the panel on the right side of the figure. The ROC area under the curve for accurately predicting non-adherence (defined as > 240 min per day of usage on all days) was fair.

Figure 3

Adherence to autotitrating positive airway pressure (autoPAP) therapy downloaded from autoPAP device after one week of therapy is plotted against adherence to continuous positive airway pressure (CPAP) therapy downloaded from the CPAP device at the end of 5 weeks of CPAP therapy. All adherence information is represented as minutes of use per day on all days of the week. Adherence to autoPAP therapy was closely related to subsequent adherence to CPAP therapy (R2 = 0.74; P < 0.0001).