Randomized Controlled Trial

Feasibility study of noninvasive ventilation with helium-oxygen gas flow for chronic obstructive pulmonary disease during exercise.

Resp Care. 2009 Sep 1;54(9):1175-82.
Review

Is Quadriceps Endurance Reduced in COPD?: A Systematic Review.

Chest. 2015 Mar 1;147(3):673-84.
Randomized Controlled Trial

Mechanisms of dyspnoea relief and improved exercise endurance after furosemide inhalation in COPD.

Thorax. 2008 Jul 1;63(7):606-13.