Helium-oxygen in the postextubation period decreases inspiratory effort

After tracheal extubation, upper and total airway resistances may frequentl y be increased resulting in an increase in inspiratory effort to breathe. W e tested whether breathing a helium-oxygen mixture (HeO2) would reduce insp iratory effort in the period after extubation. Eighteen consecutive patient s with no chronic obstructive pulmonary disease who had received mechanical ventilation (> 48 h) were successively studied immediately after extubatio n (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 pre ssure 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 cons ecutive periods; p < 0.05). PTI also differed significantly between HeO2 an d 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, w hereas gas exchange was not modified. We conclude that the use of HeO2 in t he immediate postextubation period decreases inspiratory effort and improve s comfort.