Role of ultrasound in predicting weaning failure in children undergoing
cardiac surgery: Prospective observational study
Abstract
ABSTRACT Background: Increased extravascular lung water (EVLW) induced
by systemic inflammatory response under cardiopulmonary bypass (CPB) and
diaphragmatic dysfunction due to phrenic nerve injury during cardiac
surgery leads to weaning failure from mechanical ventilation (MV) in
pediatric patients undergoing cardiac surgery. We hypothesized that
ultrasound measurement of EVLW shown by B-lines and diaphragm function
in the form of thickening and excursion will be able to predict weaning
failure defined as reintubation within 48 hours of endotracheal
extubation in such patients. Methods: Fifty patients aged (1 month to 18
years) undergoing congenital cardiac surgeries were enrolled in the
study. The ultrasound measurement of B-line of lung, diaphragm excursion
(DE) and diaphragm thickness (DT) were done preoperatively, on pressure
support ventilation (PSV) during weaning from mechanical ventilation
(MV) and 4 hours after extubation. Results: 7 out of 50 patients had
weaning failure. The patients with weaning failure (group 1, n=7) were
younger, with median age of 1 year (0.25-7) compared to those who
tolerated weaning (group 2, n=43), median age of 3 years (0.25-17),
p=0.040. The B-line score in group 1 increased from a preoperative score
of 0 to post-extubation period score of 2, the score being significantly
higher than the patients of group 2 (p=0.024). The left diaphragm
thickening fraction of <17.15% predicted weaning failure with
a sensitivity of 85%, specificity of 51.4%, (AUC ROC 0.75, p= 0.032).
Conclusion: LUS cannot predict weaning failure. The diaphragmatic
thickening fraction <17.15% was found to be a predictor of
weaning failure in our patients.