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Randomised controlled crossover trial of the effect on Ptco2 of oxygen-driven versus air-driven nebulisers in severe chronic obstructive pulmonary disease
  1. Llifon Edwards1,2,
  2. Kyle Perrin1,2,
  3. Mathew Williams1,
  4. Mark Weatherall1,2,3,
  5. Richard Beasley1,2
  1. 1Medical Research Institute of New Zealand, Wellington, New Zealand
  2. 2Respiratory Medicine Department, Capital & Coast District Health Board, Wellington, New Zealand
  3. 3Department of Medicine, University of Otago Wellington, Wellington, New Zealand
  1. Correspondence to Dr Kyle Perrin, Medical Research Institute of New Zealand, Private Bag 7902, Wellington 6242, New Zealand; kyle.perrin{at}


Background The comparative safety of oxygen versus air-driven nebulised bronchodilators in patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) is uncertain. A randomised controlled trial was performed to assess the effect on the arterial partial pressure of carbon dioxide of nebulised bronchodilator driven with oxygen versus air in stable severe COPD.

Methods In an open label randomised study, 18 subjects with stable severe COPD attended on 2 days to receive nebulised bronchodilator therapy driven by air or oxygen. Subjects received 5 mg salbutamol and 0.5 mg ipratropium bromide by nebulisation over 15 min, then, after 5 min, 5 mg salbutamol nebulised over 15 min, followed by 15 min of observation. Transcutaneous carbon dioxide tension (Ptco2) and oxygen saturations were recorded at 5 min intervals during the study. The primary outcome was the Ptco2 after the completion of the second bronchodilator treatment.

Results Ptco2 was higher with nebulised bronchodilator therapy delivered by oxygen, but decreased back to the level associated with air nebulisation 15 min after completion of the second nebulised dose. One subject experienced an increase in Ptco2 of 11 mm Hg after the first bronchodilator nebulisation driven by oxygen. The mean Ptco2 difference between the oxygen and air groups after the second nebulisation was 3.1 mm Hg (95% CI 1.6 to 4.5, p<0.001).

Conclusion Nebulisers driven with oxygen result in significantly higher levels of Ptco2 than those driven with air in patients with severe COPD.

Clinical trial registration number The study was registered on the Australian New Zealand Clinical Trials Registry (ACTRN12610000080022).

  • Carbon dioxide
  • oxygen
  • nebuliser
  • acute medicine-other
  • respiratory
  • asthma
  • pneumothorax
  • COPD

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  • An additional material is published online only. To view this file please visit the journal online (

  • Funding Funding was received from the Health Research Council of New Zealand, the Wellington Hospitals and Health Foundation, the Asthma and Respiratory Foundation of New Zealand, the Clyde Graham Charitable Trust, and the Royal Australasian College of Physicians.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval This study was approved by Central Regional Ethics Committee (CEN/09/12/093), Wellington, New Zealand.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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