Femoral Muscle Volume Change and Postextubation Respiratory Support in Infants After Cardiac Surgery

Noninvasive respiratory support following extubation is expected to reduce extubation failure; however, stratifying high-risk patients is crucial. We investigated the predictive value of femoral ultrasonography for postextubation respiratory support requirements in infants following cardiac surgery.

In this single-center, prospective observational study, infants who underwent cardiac surgery for congenital heart disease between November 2020 and September 2023 and required mechanical ventilation for >48 h were recruited. Participants were tested for extubation readiness following a standardized protocol, including a spontaneous breathing trial. Femoral ultrasonography was performed within 24 h of pediatric intensive care unit admission and 48 h before extubation. Respiratory support requirements were evaluated by a standardized protocol during the first 48 h after extubation. The prediction accuracy of the femoral muscle index (femoral muscle cross-sectional area (CSA) divided by squared height) or its change for postextubation respiratory support requirement was evaluated using receiver operating characteristic (ROC) curve analysis.

The study included 42 infants, and 26 (61.9%) subjects required respiratory support. The femoral muscle CSA exhibited a median change of -17.3% (interquartile range -24.2, -3.9) during mechanical ventilation in subjects requiring respiratory support and -9.7% (-17.6, 5.6) in those without such requirement. The area under the ROC curve (ROC-AUC) for predicting postextubation respiratory support requirement by the femoral muscle index and its percent change were 0.50 (95% CI: 0.31-0.69) and 0.63 (CI: 0.45-0.80), respectively. In contrast, body weight-adjusted tidal volume and breathing frequency before extubation demonstrated strong predictive value (ROC-AUC values of 0.81 [CI: 0.66-0.95] and 0.72 [CI: 0.56-0.89], respectively).

The femoral muscle volume and its change during mechanical ventilation provided no meaningful predictive values for postextubation respiratory support requirements in infants after cardiac surgery. Further research should assess clinical importance of muscle loss across outcomes and populations.