Heliox in the treatment of chronic obstructive pulmonary disease.

OBJECTIVE To determine if breathing helium oxygen mixtures in addition to conventional therapy in non-intubated adult chronic obstructive airways disease (COPD) patients reduces the arterial partial pressure of carbon dioxide (Paco(2)) more than conventional treatment alone, and confers an advantage in terms of the odds of intubation in the acute setting. DESIGN Meta-analysis. SETTING Diverse settings. PARTICIPANTS Adult patients with a diagnosis of either stable severe or acute COPD. MAIN OUTCOME MEASURES Decrease in partial pressure of arterial Paco(2) and intubation rates. RESULTS Combination of the results from trials measuring change in Paco(2) in COPD subjects receiving conventional therapy but breathing helium-oxygen estimated a reduction of 0.78 KPa (1.44-0.13) beyond that produced by conventional therapy with air-oxygen breathing (n = 234). Using quantitative and qualitative measures of validity it was found that most trials were unsatisfactory. Chief concerns were poor concealment of allocation and lack of blinding. Analysis excluding all papers with low methodological quality (Jadad<2) estimated the reduction in Paco(2) conferred by use of Heliox breathing to be 0.22 KPa (+0.57 to -0.14). A non-significant reduction (p = 0.2). When combined, the results from trials measuring the intubation rates of patients treated conventionally or with Heliox (n = 121) the odds ratio of intubation was 0.096 (0.03-0.27). CONCLUSION Definitive evidence of a beneficial role of Heliox in treatment of severe COPD is lacking and therefore its wide scale use cannot be recommended based on this analysis. However, as a beneficial effect of Heliox breathing was reported in all trials, further investigation with a well conducted randomised controlled trial is warranted.