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The following is a summary of “A Study on the Diagnostic Accuracy of Tidal Volume-Diaphragmatic Contraction Velocity: A Novel Index for Weaning Outcome Prediction,” published in the April 2025 issue of Critical Care Medicine by Menis et al. 

Researchers conducted a retrospective study to assess whether the volume-velocity index (VVI), derived from diaphragmatic contraction velocity and tidal volume, anticipated weaning outcomes from mechanical ventilation (MV).  

They evaluated the diagnostic accuracy of the VVI (mL*cm/s) in predicting weaning outcomes and its correlation with breathing effort indices, including esophageal pressure swings (ΔPes), the pressure-time product of esophageal pressure (PTPes), and maximal inspiratory pressure (MIP). A power analysis, based on an inception, determined the sample size for validation. Participants were enrolled through consecutive sampling, and weaning failure was defined as spontaneous breathing trial (SBT) failure or the need for MV within 48 hours.  

The results showed that in the inception (n = 30), the VVI was significantly higher in successful weaning compared to failures (764.76 [±432.61] vs 278 [±183.66], P < 0.001), VVI correlated with ΔPes (r = 0.74, R² = 0.55), the PTPes (r = 0.76, R² = 0.58), and MIP (r = 0.75, R² = 0.55), with all P-values less than 0.001. In the validation cohort (n = 40), VVI remained higher in successful weaning cases (840 [550, 1220] vs 250 [225, 302.5], P < 0.001) and predicted weaning success with an area under the receiver operating characteristic of 0.92 (95% CI, 0.83–1).  

Investigators concluded that VVI had effectively distinguished between successful and unsuccessful weaning, demonstrated a strong relationship with respiratory effort indicators, and potentially improved weaning protocols. 

Source: journals.lww.com/ccmjournal/abstract/9900/a_study_on_the_diagnostic_accuracy_of_tidal.505.aspx