Diaphragm Ultrasound for Weaning Prediction

When the abovementioned criteria were reached, patients were disconnected from the tube and a spontaneous breathing trial was attempted for 1 h administering supplemental oxygen to achieve a peripheral oxygen saturation (SpO₂) >94%. Then, each diaphragm was evaluated by B-mode and M-mode ultrasound subcostal views to rule out abnormalities in muscle movement [13 (link)]. When dysfunction of a single hemi-diaphragm was detected, patients were excluded from the study. Hereafter, right hemi-diaphragm ultrasound scans were performed with patients lying down at a semi-recumbent position (45°). Rapid shallow breathing index and maximum inspiratory pressure (PImax) were also recorded. Weaning failure was defined as the inability to maintain spontaneous breathing for at least 48 h, without any ventilatory support. Criteria for failure to the spontaneous breathing trial were the following: change in mental status, onset of discomfort, diaphoresis, respiratory rate (RR) >35 breaths/min, hemodynamic instability (heart rate >140, systolic blood pressure >180 or <90 mmHg), or signs of increased work of breathing [14 (link)]. Clinicians in charge of the patient's care were blinded to ultrasound measurements.