The Effect of Supplemental Oxygen in Obesity Hypoventilation Syndrome

Abstract

Study objectives: Low flow supplemental oxygen is commonly prescribed to patients with obesity hypoventilation syndrome (OHS). However, there is a paucity of data regarding its efficacy and safety. The objective of this study was to assess the medium-term treatment efficacy of adding supplemental oxygen therapy to commonly prescribed treatment modalities in OHS.

Methods: In this post hoc analysis of a previous randomized controlled trial, we studied 302 sequentially screened OHS patients who were randomly assigned to noninvasive ventilation, continuous positive airway pressure, or lifestyle modification. Outcomes at 2 mo included arterial blood gases, symptoms, quality of life, blood pressure, polysomnography, spirometry, 6-min walk distance, and hospital resource utilization. Statistical analysis comparing patients with and without oxygen therapy in the three treatment groups was performed using an intention-to-treat analysis.

Results: In the noninvasive ventilation group, supplemental oxygen reduced systolic blood pressure although this could be also explained by a reduction in body weight experienced in this group. In the continuous positive airway pressure group, supplemental oxygen increased the frequency of morning confusion. In the lifestyle modification group, supplemental oxygen increased compensatory metabolic alkalosis and decreased the apnea-hypopnea index during sleep. Oxygen therapy was not associated with an increase in hospital resource utilization in any of the groups.

Conclusions: After 2 mo of follow-up, chronic oxygen therapy produced marginal changes that were insufficient to consider it, globally, as beneficial or deleterious. Because supplemental oxygen therapy did not increase hospital resource utilization, we recommend prescribing oxygen therapy to patients with OHS who meet criteria with close monitoring. Long-term studies examining outcomes such as incident cardiovascular morbidity and mortality are necessary.

Clinical trials registration: Clinicaltrial.gov, ID: NCT01405976.

Keywords: noninvasive ventilation; obesity hypoventilation syndrome; oxygen therapy; sleep apnea.

© 2016 American Academy of Sleep Medicine

Figures

Figure 1. Flow chart of the study protocol.

Of the 351 selected patients, 49 were excluded, 221 had OSA (apnea-hypopnea index ≥ 30) and they were randomized into NIV, CPAP, or control groups and 81 without OSA were randomized to NIV and control groups. Patients with and without OSA randomized to NIV and control were considered together. The resulting groups (NIV, CPAP, and control) were divided in patients treated with and without supplemental oxygen therapy to be compared. CPAP, continuous positive airway pressure; NIV, noninvasive ventilation; OSA, obstructive sleep apnea.

Figure 2. Frequency of clinical symptoms in the three intervention groups (NIV, CPAP, and control) distributed in baseline with and without supplemental oxygen therapy and after 2 mo with and without supplemental oxygen therapy.

Statistically we compared the percentage at the end of the follow-up between patients with and without supplementary oxygen therapy in each of interventions groups by unadjusted analysis and the following adjusted models: (1) baseline values of the variable analyzed, age, sex, body mass index (BMI), the forced expiratory volume in 1 sec, and apnea-hypopnea index (baseline adjustment); and (2) baseline adjustment, BMI change, and CPAP or NIV compliance (hour/day); in the control group the last adjustment was only performed with BMI change. *Unadjusted p