CONTRIBUTION OF THE ENDOTRACHEAL-TUBE AND THE UPPER AIRWAY TO BREATHING WORKLOAD

The influence of the endotracheal tube (ETT) during a T-piece trial re mains controversial. Our aim was to compare the work of breathing of 1 4 successfully extubated patients at the end of a 2-h trial (T) and af ter extubation (E) of the trachea, and to assess, using the acoustic r eflection method, the resistance of the endotracheal tube and of the s upraglottic airway as well as their related work. We found that the wo rk of breathing of the patients was identical between T and E (1.72 +/ - 0.59 versus 1.63 +/- 0.45 J/L; p = 0.50 and 23.5 +/- 10.6 versus 22. 6 +/- 9.7 J/min; p = 0.70). There was no significant difference betwee n the beginning and the end of the T-piece trial (1.57 +/- 0.53 versus 1.72 +/- 0.59 J/L, p = 0.10). The work caused by the ETT amounted to 11.0 +/- 3.9% of the total work of breathing. The supraglottic airway resistance was in the normal range and was significantly smaller than the endotracheal tube resistance (0.79 +/- 0.4 versus 1.43 +/- 0.31 cm H2O . s/L; p = 0.008, flow = 0.25 L/s). We conclude that a 2-h trial of spontaneous breathing through an endotracheal tube well mimics the work of breathing performed after extubation, in patients who pass a w eaning trial and do not require reintubation.