Helium-oxygen reduces work of breathing in mechanically ventilated patients with chronic obstructive pulmonary disease

Objective To evaluate whether helium-oxygen mixture reduces inspiratory work of breathing (WOB) in sedated, paralyzed, and mechanically ventilated patients with acute exacerbation of chronic obstructive pulmonary disease (COPD).Design and setting Open, prospective, randomized, crossover study in the medical intensive care unit in a university hospital.Patients and participants 23 patients admitted for acute exacerbation of COPD and mechanically ventilated.Measurements Total WOB (WOBt), elastic WOB (WOBel), resistive WOB (WOBres), and WOB due to PEEPi (WOBPeepi) were measured. Static intrinsic positive end expiratory pressure (PEEPi), static compliance (Crs), inspiratory resistance (Rins), inspiratory (tinsp) and expiratory time constant (texp) were also measured. These variables were compared between air-oxygen and helium-oxygen mixtures.Results WOBt significantly decreased with helium-oxygen (2.34±1.04 to 1.85±1.01 J/l, p<0.001). This reduction was significant for WOBel (1.02±0.61 J/l to 0.87±0.47, p<0.01), WOBPeepi (0.77±0.38 J/l to 0.54±0.38, p<0.001), and WOBres (0.55±0.19 J/l to 0.44±0.24, p<0.05). PEEPi, Rins, tinsp and texp significantly decreased. Crs was unchanged.Conclusions Helium-oxygen mixture decreases WOB in mechanically ventilated COPD patients. Helium-oxygen mixture could be useful to reduce the burden of ventilation.