Due to its low density properties, helium-oxygen mixtures have the potential to decrease the work of breathing and possibly avoid the need for intubation and mechanical ventilation in patients with respiratory failure.To determine the effect of the addition of helium/oxygen mixtures (heliox) to standard medical care during ventilated and nonventilated acute exacerbations of COPD.Randomized controlled trials were identified from the Cochrane Airways Review Group asthma Register. Primary authors and experts were contacted. References from included and excluded studies, known reviews and texts were also searched.Studies were selected for inclusion if they compared treatment with heliox to placebo (oxygen or air) in randomized controlled trials in adults with an exacerbation of COPD.Data from all trials were combined using the Review Manager (version 4.1). We planned to perform: 1) random effects weighted mean difference (WMD), with 95

作者：G, Rodrigo；C, Pollack；C, Rodrigo；B, Rowe

来源：The Cochrane database of systematic reviews 2002 年 2期