Monitoring Noninvasive Ventilation in Patients with Obesity Hypoventilation Syndrome: Comparison between Ventilator Built-in Software and Respiratory Polygraphy

Abstract

Background: Polygraphy (PG) remains the standard method of assessing noninvasive ventilation (NIV) effectiveness. Built-in software (BIS) of recent NIV equipment provides estimates of some ventilator parameters, but their usefulness is unclear. Objectives: To assess the reliability of BIS compared with PG in a cohort of obesity hypoventilation syndrome (OHS) patients on NIV. Methods: Thirty stable OHS patients on NIV were evaluated in an outpatient setting with simultaneous PG and BIS recordings. The automated apnea-hypopnea event index (EI_AUT) provided by Rescan and manual scoring based on available traces obtained from the software (EI_BIS) were compared with manual PG scoring (EI_PG). Each manual scoring was separately performed by 2 trained operators. Agreement between the 2 operators was assessed using the kappa coefficient. Pearson correlation and Bland-Altman plots were used to evaluate agreement between EI_AUT, EI_BIS, and EI_PG. Results: Twenty-six cases were valid for analysis (age ±61 years, 17 men). All patients were ventilated in the spontaneous/timed mode (mean inspiratory positive airway pressure 17 ± 3 cm H₂O, mean expiratory positive airway pressure 10 ± 3 cm H₂O). Cohen's kappa agreement between the operators was 0.7 for EI_BIS and 0.84 for EI_PG. EI_BIS showed good correlation with EI_PG (r² = 0.79 p < 0.001), better than scoring provided by the automated analysis (r² = 0.71, p < 0.006 for EI_AUT vs. EI_PG). Conclusions: In stable OHS patients on NIV, unattended home-based monitoring using Rescan is reproducible and reliable to assess quality of ventilation when compared with PG. In addition, manual scoring of events using data obtained with this device is more consistent than software-based automated analysis.