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-cmH ₂ O PSV and 5-cmH ₂ O 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.
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