Weaning procedure
The patients were assessed daily for weaning. If they fit weaning
criteria, ERT with pressure support ventilation (PSV) for 2 hours was
performed according to our institutional protocol. The PSV settings were
set as: PEEP at 5 cm H2O, PS adjusted minimally to overcome endotracheal
tube resistance and generate a tidal volume of 4–8 ml/kg, and fiO2 at
40%. The ERT failure criteria were as follows: 1) clinical findings:
diaphoresis, nasal flaring, increased work of breathing, tachypnea
(>50% increase compared to baseline), tachycardia
(>20% increase compared to baseline), apnea, arrythmia,
hypotension, increase of >10mmHg of end-tidal carbon
dioxide compared to the baseline value 2) laboratory findings:, arterial
blood pH <7.32, decrease in arterial pH by 0.07 or more
compared to baseline, decrease in SpO2 more than 5%3.
Patients who did not fail ERT had a diaphragmatic ultrasound and were
extubated right away. Successful weaning (SW) was defined as patients
who did not require mechanical ventilation (invasive or non-invasive)
within 48 hours of extubation, whereas failed extubation (FE) was
defined as patients who required re-intubation or non-invasive
mechanical ventilation within 48 hours of extubation. Another
intensivist who was blinded to DUS measurements made the decision
regarding the need for reintubation or non-invasive ventilation
following extubation.