Heliox, dyspnoea and exercise in COPD.

One of the most important determinants of physical and mental well-being of people with chronic obstructive pulmonary disease (COPD) is participation in physical activity. The ability to alter the sensation of dyspnoea during exercise may improve both exercise duration and intensity. Despite the low density, inert nature, strong safety profile and multiple applications of helium gas, the potential benefit of helium-oxygen gas mixtures as an adjunct therapy to modify disease symptoms and exercise capabilities in obstructive lung diseases has only recently been explored. This is a systematic review of the available peer-reviewed evidence exploring whether symptom modification (perceived levels of dyspnoea) and exercise performance in COPD (either intensity or duration of work) are modified by inhalation of Heliox. Eight experimental studies met inclusion for this review. A variety of methodologies and outcome variables were used negating meta-analysis and hampering direct comparison between interventions. Overall, there was high level of evidence with a low risk of bias supporting Heliox's effectiveness in improving the intensity and endurance of exercise when compared to room air for people with COPD. Little conclusive evidence was found to determine whether Heliox altered the sensation of dyspnoea during exercise.