Hypercapnia Response in Patients with Obesity-Hypoventilation Syndrome Treated with Non-Invasive Ventilation at Home.

INTRODUCTION

Respiratory center (RC) dysfunction has been implicated in the pathogenesis of obesity-hypoventilation syndrome (OHS), and often requires treatment with home non-invasive ventilation (NIV). Our objective was to measure the effect of NIV on RC function in patients with OHS, and the factors that determine such an effect.

METHODS

We performed a prospective, repeated measures study to evaluate hypercapnia response (HR) by determining the p01/pEtCO2 ratio slope at baseline and after 6months of treatment with NIV in a group of OHS patients. A threshold of 0.22cmH2O/mmHg had previously been established in a control group, in order to differentiate optimal RC response from suboptimal RC response.

RESULTS

A total of 36 cases were included, 19 men (52%) aged 65 (SD 9) years, 63% of whom had p01/pEtCO2 below the reference value. Baseline p01/pEtCO2 was 0.17 (SD: 0.14) cmH2O/mmHg and, after 6 months of NIV, 0.30 (SD: 0.22) cmH2O/mmHg (p=0.011). After 6months of treatment with NIV, depressed RC function persisted in 12 cases (33%).

CONCLUSION

In total, 63% of OHS patients had RC dysfunction. The application of NIV improves RC function but not in all cases.