Predictive value of diaphragmatic ultrasound for weaning outcomes in mechanically ventilated patients with acute exacerbation of chronic obstructive pulmonary disease: a systematic review and meta-analysis
Weaning failure in mechanically ventilated patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) remains a critical ICU challenge that substantially increases mortality. Although point-of-care diaphragmatic ultrasound is widely proposed to guide weaning decisions, its diagnostic accuracy remains uncertain, and the optimal parameter for this high-risk population has yet to be established. We systematically searched eight databases through April 5, 2026, for studies evaluating diaphragmatic ultrasound for predicting weaning outcomes in AECOPD. After methodological quality was appraised with the QUADAS-2 tool. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR + and LR−), and diagnostic odds ratios were estimated using bivariate random-effects models, and overall diagnostic performance was summarized by the area under the summary receiver operating characteristic curve. Fagan nomograms were constructed to illustrate changes from pre-test to post-test probability. Threshold effects and heterogeneity were assessed using Spearman correlation and the Q test with the I² statistic, respectively. Exploratory meta-regression, leave-one-out sensitivity analyses, and Deeks’ test were used to investigate sources of heterogeneity, assess result stability, and evaluate funnel-plot asymmetry. Twenty-three studies comprising 2,000 patients (1,310 successes, 690 failures) were included. Of 14 distinct ultrasound parameters identified, four provided sufficient data for quantitative synthesis. Diaphragmatic excursion (DE, n = 16) showed the most robust and balanced performance, with a pooled sensitivity of 0.85, specificity of 0.85, and an AUC of 0.92. Diaphragm thickening fraction (DTF, n = 13) also showed good accuracy (sensitivity 0.84, specificity 0.77, AUC 0.88). The diaphragmatic rapid shallow breathing index (D-RSBI, n = 8) showed high specificity (0.88) but moderate sensitivity (0.74; AUC 0.85), whereas diaphragmatic contraction velocity (DCV, n = 4) showed only moderate accuracy (AUC 0.70). Substantial heterogeneity was observed for DE, DTF, and D-RSBI. Diaphragm ultrasound, particularly DE, may provide useful prognostic information for weaning outcomes in mechanically ventilated patients with AECOPD, while D-RSBI may help identify patients at high risk of weaning failure. However, given the small, predominantly single-centre studies, post hoc study-specific thresholds, substantial heterogeneity, and geographical concentration of the evidence, these findings represent apparent prognostic performance rather than externally validated diagnostic accuracy. Diaphragm ultrasound should therefore be used as an adjunct rather than the sole basis for weaning decisions, pending multicentre external validation and interventional trials demonstrating improved patient-important outcomes.