Association between respiratory-related cortical activation and weaning from mechanical ventilation: a physiological...

In mechanically ventilated patients, extubation is decided after passing a spontaneous breathing trial (SBT). Supplementary motor area, which can be non-invasively assessed by measuring amplitude of pre-inspiratory potentials (PIPs), is recruited in case of increased respiratory effort. Weaning failure may be accompanied by increased respiratory effort. We hypothesized that early increased PIP amplitude from the start of SBT may be associated with SBT failure.

We performed a single-center physiological prospective study in mechanically ventilated patients meeting weaning criteria. PIP amplitude was measured using electroencephalography under mechanical ventilation and then during the first 15-min of the SBT performed using a T-piece. We compared respiratory-related cortical activation between patients who passed a 1-h SBT and those who failed.

Among the 62 patients included, 17 (27%) failed the SBT. Whereas patients who failed the SBT had a lower median amplitude of PIPs under mechanical ventilation than those who passed the SBT (0.6 µV [IQR, 0-1.3] vs. 1.9 [1.2-2.9], p < 0.0001), they had a higher amplitude of PIPs at the beginning of the SBT (2.1 µV [IQR, 1.7-2.9] vs. 1.2 [0.5-2.0], p < 0.005). PIP amplitude between mechanical ventilation and SBT significantly increased in case of SBT failure whereas it decreased in case of SBT success (+ 1.7 µV [1.2-2.1] vs. -0.5 [-1.8-0.1], p < 0.0001). An increase of PIP above 0.43 µV was associated with SBT failure with sensitivity of 100% and specificity of 87%.

The demonstration of an association between increased respiratory-related cortical activation and failure of the weaning trial is a physiological marker of interest for better phenotyping of patients ready for weaning.