Anesthésie et recherche clinique
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Evaluation of Ventilator-induced Diaphragmatic Dysfunction by Diaphragmatic Excursion During Spontaneous Breathing Trials

Yasser Sadek Nassar*, Mahmoud Elbanna, Moamen Arafa and Ashraf Hussein

Introduction: Ventilator-induced diaphragmatic dysfunction (VIDD) leads to difficulties in weaning. Diaphragmatic excursion assessment by ultrasonography is a feasible bedside assessment of the diaphragm in the ICU. Our primary aim was to identify the presence of VIDD using US in patients undergoing Spontaneous breathing trials (SBT). Our secondary aim was to assess the impact of VIDD impact on weaning outcome.
Methods: This study was conducted in the Critical Care Department of Cairo University Hospital between March 2014 and March 2015. All consecutive subjects who required MV for ≥ 72 h and were ready for SBT were prospectively recruited. Exclusion criteria: Any history of aminoglycoside use, paralytics, central or neuromuscular disease, chemotherapy, cachexia, severe electrolyte imbalance or intra-abdominal pressure (IAP)>7 mmHg Thirty minutes from the start of SBT, each hemi-diaphragm was evaluated by M-mode sonography with the patient in the supine position. Five measurements were recorded and averaged. Ventilator Induced diaphragmatic dysfunction (VIDD) was diagnosed if diaphragmatic excursion (DE) was <10 mm. Patients were classified into two groups: the non-diaphragmatic dysfunction (NDD) group and the VIDD group. Patients were monitored for weaning and 30 day mortality.
Results: Fifty subjects (100%) were studied. The VIDD group included 24 (48%) subjects, and the NDD group included 26 (52%) subjects. There were no significant differences in age, sex, weight or comorbidities between the two groups (p>0.05). Successful weaning was present in [18/26 (69%) vs. 13/24 (54.2%), p=0.06] and weaning time was shorter [29 ± 18 vs. 43 ± 28 h, p=0.02] in the NDD group versus the VIDD group respectively. The median DE was higher in successfully weaned vs. failed weaning subjects [14.4 (1.9-40) vs. 9.2 (6.6-35.1), p=0.01]. The receiver operator characteristic curves (ROC) showed a cut-off for weaning DE 14 mm for right hemi-diaphragm with an area under the curve (AUC) 0.8.
Conclusions: VIDD is present in nearly half of our mechanically ventilated patients ≥ 72 h. VIDD is associated with lower DE and longer weaning time. Diaphragmatic excursion may serve as a valuable tool for predicting weaning outcome as traditional volumetric respiratory indices.