Comparative effects of helium-oxygen and external positive end-expiratory pressure on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in mechanically ventilated patients with chronic obstructive pulmonary disease

Publisher Website
Google Scholar
Abstract
To compare the effects of He/O2 and external PEEP (PEEPe) on intrinsic PEEP (PEEPi), respiratory mechanics, gas exchange, and ventilation/perfusion (V̇A/Q̇) in mechanically ventilated COPD patients. Prospective, interventional study in the intensive care unit of a university hospital. Ten intubated, sedated, paralyzed, mechanically ventilated COPD patients studied in the following conditions: (a) baseline settings made by clinician in charge, air/O2, ZEEP; (b) He/O2, ZEEP; (c) air/O2, ZEEP; (d) air/O2, PEEPe 80% of PEEPi. Measurements at each condition included V̇A/Q̇ by the multiple inert gas elimination technique (MIGET). PEEPi and trapped gas volume were comparably reduced by He/O2 (4.2±4 vs. 7.7±4 cmH2O and 98±82 vs. 217±124 ml, respectively) and PEEPe (4.4±1.3 vs. 7.8±3.6 cmH2O and 120±107 vs. 216±115 ml, respectively). He/O2 reduced inspiratory and expiratory respiratory system resistance (15.5±4.4 vs. 20.7±6.9 and 19±9 vs. 28.8±15 cmH2O l−1s−1, respectively) and plateau pressure (13±4 vs. 17±6 cmH2O). PEEPe increased airway pressures, including total PEEP, and elastance. PaO2/FIO2 was slightly reduced by He/O2 (225±83 vs. 245±82) without significant V̇A/Q̇ change. He/O2 and PEEPe comparably reduced PEEPi and trapped gas volume. However, He/O2 decreased airway resistance and intrathoracic pressures, at a small cost in arterial oxygenation. He/O2 could offer an attractive option in COPD patients with PEEPi/dynamic hyperinflation.