Helium-oxygen decreases inspiratory effort and work of breathing during pressure support in intubated patients with chronic obstructive pulmonary disease

Objective To evaluate the impact of helium-oxygen (He/O₂) on inspiratory effort and work of breathing (WOB) in intubated COPD patients ventilated with pressure support.Design and setting Prospective crossover interventional study in the medical ICU of a university hospital.Patients and participants Ten patients.Interventions Sequential inhalation (30 min each) of three gas mixtures: (a) air/O₂, (b) He/O₂ (c) air/O₂, at constant FIO₂ and level of pressure support.Measurements and results Inspiratory effort and WOB were determined by esophageal and gastric pressure. Throughout the study pressure support and FIO₂ were 14±3 cmH₂O and 0.33±0.07 respectively. Compared to Air/O₂, He/O₂ reduced the number of ineffective breaths (4±5 vs. 9±5 breaths/min), intrinsic PEEP (3.1±2 vs. 4.8±2 cmH₂O), the magnitude of negative esophageal pressure swings (6.7±2 vs. 9.1±4.9 cmH₂O), pressure-time product (42±37 vs. 67±65 cmH₂O s^–1 min^–1), and total WOB (11±3 vs. 18±10 J/min). Elastic (6±1 vs. 10±6 J/min) and resistive (5±1 vs. 9±4 J/min) components of the WOB were decreased by He/O₂.Conclusions In intubated COPD patients ventilated with pressure support He/O₂ reduces intrinsic PEEP, the number of ineffective breaths, and the magnitude of inspiratory effort and WOB. He/O₂ could prove useful in patients with high levels of PEEPi and WOB ventilated in pressure support, for example, during weaning.Funding was provided by the Swiss National Scientific Research Fund (grant #32-63501.00)