Helium-oxygen in the postextubation period decreases inspiratory effort.

ABSTRACT

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 (HeO(2)) 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 (N(2)O(2)), 15 min after breathing HeO(2), and after return to N(2)O(2). Effort to breathe, assessed by the transdiaphragmatic pressure swings (DeltaPdi) 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 HeO(2) was 19 +/- 5%. All but three patients presented a decrease in transdiaphragmatic pressure under HeO(2), ranging from - 4 to - 55%, and a significant reduction in DeltaPdi was observed between HeO(2) and N(2)O(2) (10.2 +/- 0.7 versus 8.6 +/- 1.1 versus 10.0 +/- 0.8 cm H(2)O for the three consecutive periods; p < 0.05). PTI also differed significantly between HeO(2) and N(2)O(2) (197 +/- 19 versus 166 +/- 22 versus 201 +/- 23 cm H(2)O/s/min for the three periods; p < 0.05). Breathing HeO(2) significantly improved comfort, whereas gas exchange was not modified. We conclude that the use of HeO(2) in the immediate postextubation period decreases inspiratory effort and improves comfort.