Ultrasonic Assessment of Diaphragm Function in the Ventilator Liberation of Perioperative Patients

Objective: Diaphragm ultrasonography can predict weaning failure; however, only a small number of studies include the majority of surgery patients. This study seeks to investigate the feasibility of diaphragm ultrasonography-guided ventilator separation in intubated surgical patients. Patients and Methods: This prospective observational study was conducted in postoperative mechanical ventilated patients at Surgical ICU, Maharaj Nakorn Chiang Mai Hospital, from September 2020 to September 2022. Diaphragm thickness (TDi) and diaphragm excursion (DE) were measured with ultrasonography during spontaneous breathing trials. We analyzed the correlation of diaphragm function to weaning success or failure. A weaning failure was defined as death or reintubation within 7 days after extubation (whether post-extubation noninvasive ventilation was used or not). Results: 105 mechanically ventilated patients were prospectively recruited in the weaning failure group, 15 patients, and 90 patients in the weaning success group. The overall weaning failure rate was 14.29%. Patients who had undergone thoracic surgery significantly failed weaning more than those who had not (33% vs 11%, p-value 0.023). TDi at inspiration and expiration, both left and right diaphragm, DTF, and left DE did not differ significantly between patients who succeeded or failed ventilator weaning. Only right DE significantly differed between groups which were 6.7 [6.4-8.4] mm and 9.6 [7.4-14] mm (p-value 0.016) in the weaning failure group and success group, respectively. According to the ROC curve, a cutoff value of right diaphragm excursion > 7.3 mm was associated with a successful weaning with a sensitivity of 76.92%, a specificity of 69.23%, a positive predictive value of 93.75%, and a negative predictive value of 33.34%. Conclusions: This study shows that in our cohort of postoperative patients, the assessment of right diaphragm excursion by ultrasound potentially predicts weaning success with a cutoff value > 7.3 mm (sensitivity of 76.92%, a specificity of 69.23%).