Hemodynamic Impact of the Spontaneous Ventilation Test in Patients at Risk of Weaning Pulmonary Oedema

Weaning-induced pulmonary edema (WIPE) from the ventilator is a frequent cause of extubation failure or delay, which prolongs the duration of invasive mechanical ventilation and the associated morbidity and mortality. WIPE is a very frequent cause of extubation failure in at-risk patients. A spontaneous breathing trial (SBT) is performed before extubating a patient, either by disconnecting the patient from the ventilator (T-piece SBT) or by setting the ventilator to spontaneous breathing mode with pressure support at 7 cm H2O and zero positive end-expiratory pressure (PS-ZEEP SBT). There is currently no recommendation regarding which SBT modality should be used, particularly in patients at risk of WIPE. The hemodynamic changes induced by the SBT can lead to WIPE, which typically develops within minutes of the SBT onset.

The hypothesis being tested is that, by altering intrathoracic pressure during the patient's inspiration (negative pressure), the T-piece SBT leads to a greater increase in left ventricular filling pressures compared to the PS-ZEEP SBT.