Relationship of Ultrasonically Assessed Diaphragmatic Weakness with the Need for Postoperative Mechanical Ventilation in Older Adult Patients after Major Abdominal Surgeries: An Observational Study.

OBJECTIVE: This study aimed to analyze the association between preoperative diaphragmatic weakness in older adult patients and the need for postoperative mechanical ventilation after major surgery. We hypothesized that preoperative diaphragmatic weakness would significantly increase the need for postoperative mechanical ventilation. METHODS: It was a single-center, prospective, observational study that included 90 older adult patients aged more than 50 years who underwent abdominal surgery under general anaesthesia. A portable ultrasound was used to assess the percentage increase in the diaphragm thickening fraction (TFdi) during a maximal inspiratory effort, preoperatively and before extubation. The perioperative change in diaphragmatic function, the development of outcomes, i.e., extubation/mechanical ventilation, and the optimal cut-off of TFdi to predict outcomes were analyzed. RESULTS: The patients with a preoperative TFdi <35% had a higher requirement for mechanical ventilation (24.5% or 1:3) as compared to those with TFdi ≥35% (7.3% or 1:13). In multivariate linear regression analysis, TFdi (preoperative) was the only independent predictor of TFdi (before extubation), explaining a substantial proportion of the variance (adjusted R2=0.71). The optimal cut-off value of TFdi (preoperative) ≤28.9 predicted intensive care unit stay with 73% sensitivity and 73% specificity, and a high negative predictive value (93.2%). CONCLUSION: Our study found that a significant percentage of older adult patients had a preexisting diaphragmatic weakness that was associated with extubation failure and the need for postoperative mechanical ventilation.