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

Abstract

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. © Springer-Verlag 2005.