Comparing lung aeration and respiratory effort using two different spontaneous breathing trial: T-piece vs pressure support ventilation

Objective

To assess the changes in lung aeration and respiratory effort generated by two different spontaneous breathing trial (SBT): T-piece (T-T) vs pressure support ventilation (PSV).

Design

Prospective, interventionist and randomized study.

Setting

Intensive Care Unit (ICU) of Hospital del Mar.

Participants

Forty-three ventilated patients for at least 24 h and considered eligible for an SBT were included in the study between October 2017 and March 2020.

Interventions

30-min SBT with T-piece (T-T group, 20 patients) or 8-cmH₂O PSV and 5-cmH₂O positive end expiratory pressure (PSV group, 23 patients).

Main variables of interest

Demographics, clinical data, physiological variables, lung aeration evaluated with electrical impedance tomography (EIT) and lung ultrasound (LUS), and respiratory effort using diaphragmatic ultrasonography (DU) were collected at different timepoints: basal (BSL), end of SBT (EoSBT) and one hour after extubation (OTE).

Results

There were a loss of aeration measured with EIT and LUS in the different study timepoints, without statistical differences from BSL to OTE, between T-T and PSV [LUS: 3 (1, 5.5) AU vs 2 (1, 3) AU; p = 0.088; EELI: −2516.41 (−5871.88, 1090.46) AU vs −1992.4 (−3458.76, −5.07) AU; p = 0.918]. Percentage of variation between BSL and OTE, was greater when LUS was used compared to EIT (68.1% vs 4.9%, p ≤ 0.001). Diaphragmatic excursion trend to decrease coinciding with a loss of aeration during extubation.

Conclusion

T-T and PSV as different SBT strategies in ventilated patients do not show differences in aeration loss, nor estimated respiratory effort or tidal volume measured by EIT, LUS and DU.