Helium-oxygen in the postextubation period decreases inspiratory effort

After tracheal extubation, upper and total airway resistances may frequently be increased resulting in an increase in inspiratory effort to breathe. We tested whether breathing a helium-oxygen mixture (HeO2) would reduce inspiratory effort in the period after extubation. Eighteen consecutive patients with no chronic obstructive pulmonary disease who had received mechanical ventilation (> 48 h) were successively studied immediately after extubation (N2O2), 15 min after breathing HeO2, and after return to N2O2. Effort to breathe, assessed by the transdiaphragmatic pressure swings (Delta Pdi) and the pressure-time index of the diaphragm (PTI), comfort, and gas exchange, were the main end points. The mean reduction of the transdiaphragmatic pressure under HeO2 was 19 +/- 5%. All but three patients presented a decrease in transdiaphragmatic pressure under HeO2, ranging from - 4 to - 55%, and a significant reduction in Delta Pdi was observed between HeO2 and N2O2 (10.2 +/- 0.7 versus 8.6 +/- 1.1 versus 10.0 +/- 0.8 cm H2O for the three consecutive periods; p < 0.05). PTI also differed significantly between HeO2 and N2O2 (197 +/- 19 versus 166 +/- 22 versus 201 +/- 23 cm H2O/s/min for the three periods; p < 0.05). Breathing HeO2 significantly improved comfort, whereas gas exchange was not modified. We conclude that the use of HeO2 in the immediate postextubation period decreases inspiratory effort and improves comfort