Rodrigo G, Pollack C, Rodrigo C, Rowe B
Departamento de Emergencia, Hospital Central de las FF.AA., Av. 8 de Octubre 3020', Montevideo, Uruguay, 11600.
Cochrane Database Syst Rev. 2002;2001(2):CD003571. doi: 10.1002/14651858.CD003571.
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% confidence intervals (95% CI), 2) Homogeneity of effect sizes with the Dersimonian and Laird method with p<0.1 as the cut point for significance, and 3) sensitivity analysis on different helium-oxygen mixtures (80/20 vs 70/30), and 4) methodological quality (Jadad score >2 vs. <3).
Four studies, all published between 1997 and 2000 met the inclusion criteria. Two studies compared heliox-oxygen vs. air-oxygen in decompensated COPD patients who were not ventilated. One study was performed in mechanical ventilated patients and one in patients undergoing noninvasive pressure support (NIPSV) ventilated patients. Data could be obtained for only two of the studies. One was a randomized crossover study of 70:30 helium-oxygen vs air-oxygen that involved nineteen patients with acute severe COPD, hospitalized in an intensive care unit for NIPSV. In the patients receiving heliox, arterial PCO2 fell more; WMD 0.8 kPa (95% CI 0.26, -1.34). The second was a randomized trial involved 47 patients with acute COPD, who presented to an Emergency Department randomized to receive updraft nebulization of albuterol and ipratropium bromide using 80% helium and 20% oxygen or compressed air as the driving gas. Treatments were administered at 0, 20, 40, and 120 minutes after randomization. There were no significant differences in the change of FEV1 and FVC between the two groups by either the 1 or 2 hours point. although a small improvement in FEF 25-75 was significantly greater in the heliox group than in the air group.
REVIEWER'S CONCLUSIONS: There is currently insufficient evidence to support the use of helium-oxygen mixtures to treat acute exacerbations of COPD in either ventilated or nonventilated patients. Suitably designed randomised controlled trials with the endpoint being the avoidance of mechanical ventilation may be justified.
由于氦氧混合气的低密度特性，其有可能降低呼吸功，并可能避免呼吸衰竭患者进行气管插管和机械通气。
确定在慢性阻塞性肺疾病（COPD）通气和非通气急性加重期，在标准医疗护理基础上加用氦氧混合气（氦氧混合气）的效果。
从Cochrane气道综述组哮喘注册库中识别随机对照试验。联系了主要作者和专家。还检索了纳入和排除研究、已知综述及文献中的参考文献。
若研究在COPD急性加重期的成年患者中进行随机对照试验，比较氦氧混合气治疗与安慰剂（氧气或空气），则纳入研究。
使用Review Manager（4.1版）合并所有试验的数据。我们计划进行：1）随机效应加权平均差（WMD），95%置信区间（95%CI）；2）采用Dersimonian和Laird方法进行效应量齐性检验，以p<0.1作为显著性界值；3）对不同氦氧混合气（80/20与70/30）进行敏感性分析；4）方法学质量（Jadad评分>2与<3）。
四项均发表于1997年至2000年间的研究符合纳入标准。两项研究比较了未通气的失代偿性COPD患者中氦氧混合气与空气-氧气。一项研究在机械通气患者中进行，另一项在接受无创压力支持（NIPSV）通气的患者中进行。仅两项研究可获得数据。一项是70:30氦氧混合气与空气-氧气的随机交叉研究，涉及19例急性重度COPD患者，在重症监护病房接受NIPSV住院治疗。接受氦氧混合气治疗的患者动脉PCO2下降更多；WMD 0.8 kPa（95%CI 0.26，-1.34）。第二项是一项随机试验，涉及47例急性COPD患者，他们到急诊科就诊，随机接受使用80%氦气和20%氧气或压缩空气作为驱动气体的沙丁胺醇和异丙托溴铵上吸雾化治疗。在随机分组后0、20、40和120分钟给予治疗。在1小时或2小时时，两组间FEV1和FVC的变化无显著差异。尽管在25%-75%用力呼气流量（FEF 25-75）方面，氦氧混合气组比空气组有显著的小幅度改善。
目前尚无足够证据支持在通气或非通气患者中使用氦氧混合气治疗COPD急性加重期。设计适当的以避免机械通气为终点的随机对照试验可能是合理的。
