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.

Usefulness of diaphragmatic ultrasound in the early diagnosis of phrenic nerve palsy after shoulder surgery in the prevention of post-operative respiratory complications

Phrenic nerve block is a complication that can occur after brachial plexus anaesthesia above the clavicle. The main consequence of this blockage is ipsolateral diaphragmatic paralysis, which can sometimes lead to the appearance of post-operative respiratory complications. A case is presented on a woman, who after having undergone a total shoulder prosthesis, presented with dyspnoea in the post-operative recovery unit. A diaphragmatic ultrasound was performed that enabled a rapid diagnosis to be made of a complete paralysis of the ipsolateral hemi-diaphragm. Given the suspicion of phrenic nerve block, ultrasound has proven to be a rapid diagnostic tool with high sensitivity and specificity. Its use can anticipate the possible development of immediate complications, and act as a guide in choosing the appropriate therapeutic strategy for each case in an early manner. In this case it enabled us to treat early with oxygen therapy, interscalene catheter removal, and intensive surveillance.