Clinical Question: Does a combination of helium and oxygen improve exercise capacity in patients with chronic obstructive pulmonary disease (COPD)?

Setting: Outpatient (specialty)

Study Design: Crossover trial (randomized)

Synopsis: The researchers studied 82 patients with stable COPD who complained of exertional dyspnea. Patients were former smokers and continued their usual medication during the study. Over several visits, each patient underwent various tests of exercise capacity and lung function before and after exposure to medical air (ambient air inspired via tubing), one of two concentrations of helium and oxygen (72/28 percent; 79/21 percent), or one of two concentrations of nitrogen and oxygen (72/28 percent; 79/21 percent). Additionally, patients recorded their ratings of perceived exertion. Seventy-five patients completed all phases of the study.

Patients breathing medical air walked a shorter distance than any of the other groups of patients. Among patients breathing various helium mixtures, there was no significant difference in walking distance or in their rating of perceived exertion. On average, patients breathing 72 percent helium were able to walk more than 426 ft (130 m) farther than those breathing medical air, and they experienced significant improvement in their ratings of exertion (although the latter improvement was of borderline clinical significance). Blinding was maintained by having patients not talk during and for two minutes after the test to prevent anyone from hearing the estimated two-octave rise in the voice caused by the helium. Although this study addressed medically stable patients, a Cochrane review of four small studies in 2000 concluded that the evidence in support of helium/oxygen mixtures for acute exacerbations was inconclusive.

Bottom Line: Inhaling a combination of 72 percent helium and 28 percent oxygen during exertion increases the comfortable walking distance and reduces the perception of exertional difficulty in patients with stable COPD. (Level of Evidence: 2b)