Assessment of Changes in Diaphragm Thickness to Predict Extubation Outcomes After Prolonged Upper Abdominal Surgery

Background: Prolonged upper abdominal surgery causes postoperative pulmonary complications, such as weaning failure. The diaphragmatic thickening fraction (DTF) is regarded as the surrogate of the breathing workload and correlates well with diaphragm strength. Compromised diaphragm function negatively influences ventilation, leading to difficulty in weaning from a mechanical ventilator. The objectives of the study were to estimate the changes in diaphragm thickness and the best cutoff value that will predict extubation failure at the end of prolonged upper abdominal elective surgery. Methods: In this prospective observational study, 120 patients (aged 18-70 years) of either sex and with American Society of Anesthesiologists physical status I or II, scheduled to undergo upper abdominal surgery lasting four hours or more, were included. Patients taking more than 30 minutes to extubate from the time of administration of the reversal agent were categorized as failure to extubate. The DTF was assessed via ultrasonography. Results: Twenty-five (20.83%) patients had failed extubation. Sex (P = 0.001) and pre-extubation DTF (P < 0.001) were identified as significant variables distinguishing patients who were successfully extubated from those who failed extubation. Multivariate logistic analysis showed that female sex (odds ratio (OR) = 0.233; P = 0.010) and pre-extubation DTF (OR = 1.071; P = 0.001) were significantly associated with successful extubation. A pre-extubation DTF cutoff of >22.63% predicted successful extubation with a sensitivity of 88.04%, a specificity of 56.0%, and an area under the receiver operating characteristic curve (AUC-ROC) of 0.752 Conclusions: Diaphragmatic dysfunction is common after prolonged upper abdominal surgery, and DTF may help identify patients at risk of extubation failure.