(1739) Diaphragmatic Ultrasound to Predict Mechanical Ventilation Liberation in Postoperative Patients

Introduction: As diaphragm ultrasound(US) evaluation has recently emerged as a predictor of mechanical ventilation liberation, few data exist on the use of diaphragm US indices in surgical patients. As diaphragm dysfunction has been associated with extubation failure, and ultrasonography studies have demonstrated decreased diaphragm function following surgical intervention, we sought to assess diaphragm thickening fraction(DTf), diaphragmatic excursion(DE), and diaphragm-rapid shallow breathing index(D-RSBI) as predictors of successful weaning from mechanical ventilation in post-operative patients.

Methods: This was a prospective observational cohort study from 6/2022 to 6/2024, that enrolled adult patients(≥18 years) on mechanical ventilation for ≥48hours following surgical intervention. Right-sided diaphragm ultrasound evaluations were conducted by the study team 30 minutes following spontaneous breathing trials to measure DTf, DE, and D-RSBI; the clinical team was blinded. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were measured. Mann-Whitney U, Fisher’s Exact, and multivariable logistic regression analyses were completed.

Results: 48 SICU patients were enrolled, 35(72.9%) were successfully extubated and 13(27.1%) required reintubation within 72 hours. All patients underwent surgery (54.2% abdominal, 23.0% orthopedic/spine, 18.7% head and neck, 12.4% cardiothoracic). There was no difference in demographic nor admission data analysis between those who succeeded vs failed liberation. There was no difference in DTf (0.4±0.2 vs 0.3±0.1, AUC 0.65, p=0.054), DE (12.7±6.8 vs 16.2±10.9, AUC 0.42, p=0.301), or D-RSBI (2.1±1.7 vs 1.6±1.1, AUC 0.56, p=0.329), between patients who succeeded vs failed extubation. Despite inadequacy of individual parameters, multivariable logistic regression adjusted for age and BMI, demonstrated greater accuracy of diaphragm ultrasound indices (DTf OR 0.001, p=0.037, AUC 0.76).

Conclusions: This study suggests that while individual diaphragmatic US weaning indices may not be generalizable to post-operative patients to predict successful liberation from mechanical ventilation, the combined use of DTf, DE, and D-RSBI may still be helpful to provide moderate predictive accuracy for extubation among mechanically ventilated surgical and trauma patients.