Parasternal intercostal muscle thickening fraction predicts weaning failure in invasively ventilated patients with COPD: a prospective observational study.

Abstract

Background: Weaning from invasive mechanical ventilation (IMV) is a critical phase of intensive care in patients with chronic obstructive pulmonary disease (COPD), in whom weaning failure is associated with increased morbidity and prolonged intensive care unit stay. Although diaphragm ultrasonography has been extensively studied, the contribution of accessory respiratory muscles during the weaning process remains insufficiently explored. We aimed to investigate whether parasternal intercostal muscle thickening fraction (IMTF), assessed by ultrasound, is associated with weaning outcomes in invasively ventilated patients with COPD.

Methods: In this prospective observational study, patients with COPD undergoing IMV were evaluated immediately before their first spontaneous breathing trial (SBT). Parasternal intercostal muscle thickness was measured at end-expiration and end-inspiration using ultrasound, and IMTF was calculated. Weaning success or failure was defined according to standard criteria. Associations between IMTF and weaning outcomes were examined using univariable and multivariable logistic regression models adjusting for gas exchange parameters and illness severity scores.

Results: A total of 131 patients were included; 106 (81.0%) were successfully weaned, while 25 (19.0%) experienced weaning failure. IMTF was significantly higher in patients with weaning failure compared with those successfully weaned (11.9±1.7% vs 7.4±1.8%, p<0.001). Higher IMTF was associated with impaired gas exchange, showing an inverse correlation with PaO₂/FiO₂ and a positive correlation with PaCO₂ measured at initiation of IMV (both p <0.001). In separate multivariable models, IMTF remained independently associated with weaning failure after adjustment for gas-exchange parameters, APACHE II score or SOFA score, with ORs ranging from approximately 3.3 to 4.0 per 1-percentage-point increase in IMTF.

Conclusions: In invasively ventilated patients with COPD, increased parasternal IMTF measured immediately before the first SBT was independently associated with weaning failure. Parasternal intercostal muscle ultrasound may provide complementary information during weaning assessment.