Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea

Abstract

Background: Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure.

Methods: Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis.

Results: A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of -6 (95% CI -7.7 to -4.2) mm Hg versus -2.8 (95% CI -4.3 to -1.3) mm Hg, (p<0.001) and serum bicarbonate of -3.4 (95% CI -4.5 to -2.3) versus -1 (95% CI -1.7 to -0.2 95% CI) mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group.

Conclusions: NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality.

Trial registration number: NCT01405976; results.

Keywords: Non invasive ventilation; Sleep apnoea.

Figure 1

Flow chart of the study protocol. Of the 365 selected patients, 58 were excluded, 221 had severe OSA and 86 were randomised. A dropout in the control group was due to hospital admission requiring NIV treatment for more than 5 days. OSA, obstructive sleep apnoea; ITT, intention to treat; NIV, non-invasive ventilation.

Figure 2

Inter-group changes in arterial carbon dioxide tension (PaCO₂) (means and 95% of CIs) adjusted according to basic adjustments (baseline PaCO₂, age, sex, body mass index and apnoea–hypopnoea index), weight change and non-invasive ventilation (NIV) use (more or less than 4 hours/night).

Figure 3

Changes in the percentages of clinical symptoms in the two groups. Non-invasive ventilation (NIV) achieved more important improvement than the control group, with statistical intra-group differences for unrefreshing sleep and tiredness.