Thorax 68:854-859 doi:10.1136/thoraxjnl-2013-203508
  • Sleep disordered breathing
  • Original article

The effects of Provent on moderate to severe obstructive sleep apnoea during continuous positive airway pressure therapy withdrawal: a randomised controlled trial

  1. Malcolm Kohler1,4
  1. 1Sleep Disorders Centre and Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland
  2. 2Oxford Centre for Respiratory Medicine, Churchill Hospital and NIHR Biomedical Research Centre, Oxford, UK
  3. 3Centre for Statistics in Medicine, Oxford University, Oxford, UK
  4. 4Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
  1. Correspondence to Prof Malcolm Kohler, Division of Pulmonology, University Hospital Zurich, Raemistrasse 100, Zurich 8091, Switzerland; malcolm.kohler{at}
  • Received 1 March 2013
  • Revised 24 April 2013
  • Accepted 5 May 2013
  • Published Online First 30 May 2013


Objectives The aim of this study was to test the effectiveness of Provent, an expiratory nasal resistance valve, to prevent the recurrence of OSA following CPAP withdrawal.

Design Randomised, partially blinded, parallel, placebo-controlled trial.

Setting Outpatient sleep clinics in the UK (Oxford) and Switzerland (Zurich).

Participants 67 patients with OSA receiving CPAP were randomised to one of three groups for 2 weeks: continuing CPAP, Provent or placebo Provent.

Main outcome measures Primary outcomes included for Provent versus placebo Provent, OSA severity (oxygen desaturation index (ODI), apnoea–hypopnoea index (AHI)) and Epworth Sleepiness Scale (ESS) score. Secondary outcomes for Provent versus placebo Provent included ODI from ambulatory pulse oximetry and blood pressure (BP). For CPAP versus Provent, or CPAP versus placebo Provent, secondary outcomes included ODI/AHI, ESS and BP.

Results 63 patients were included in the per protocol analysis. OSA recurred in the Provent (ODI 35.8, SD 17.4) and placebo Provent (ODI 28.2, SD 18.3) groups, and there was no significant difference in ODI, AHI and ESS between Provent and placebo Provent at 2 weeks (mean difference ODI −1.0, 95% CI −10.0 to +12.0, p=0.85; AHI +3.2, 95% CI −7.7 to +14.1, p=0.52; and ESS −1.4, 95% CI −4.1 to +1.4, p=0.33). ODI from ambulatory pulse-oximetry and BP at 2 weeks were not different in the Provent versus placebo Provent groups. ODI, AHI and BP, but not ESS, were significantly higher in the Provent and placebo Provent groups compared with CPAP.

Conclusions Provent cannot be recommended as an alternative short-term therapy for patients with moderate to severe OSA already on CPAP.

TrialRegNo NCT01332175.

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