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Low CT-Derived Thoracic Muscle Area and Composite Weaning Failure in Mechanically Ventilated ICU Patients with
Seonghye Jung1, Kwonhyung Hyung2,3, Heemoon Park2,3
1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Seoul National University, Seoul 03080, Republic of Korea.
Insights
Low thoracic muscle mass in ventilated pneumonia patients is linked to weaning failure, particularly in those younger than 75 years. This finding suggests muscle mass is a key factor in recovery, regardless of age.
Area of Science:
- Critical Care Medicine
- Pulmonology
- Radiology
Background:
- Prognostic value of low skeletal muscle mass in ventilated patients is not well-established.
- Age-related differences in the impact of low muscle mass on ventilator liberation are unknown.
Purpose of the Study:
- To assess if the association between low computed tomography (CT)-derived thoracic muscle area and ventilator-liberation outcomes differs by age.
- Investigate the prognostic contribution of low skeletal muscle mass in ventilated patients across different age groups.
Main Methods:
- Retrospective cohort study of 607 adults with pneumonia requiring invasive ventilation.
- Thoracic muscle area quantified using deep-learning segmentation on chest CT scans.
- Primary outcome: composite weaning failure; analysis stratified by age (75 years) with interaction testing.
Main Results:
- Low thoracic muscle area was associated with composite weaning failure in younger patients (aOR 3.63) but not significantly in older patients (aOR 1.68).
- A graded association was observed across muscle area quartiles in both age strata.
- No significant association with ICU mortality, but exploratory analysis showed higher 7-day mortality in younger patients with low muscle area.
Conclusions:
- Low CT-derived thoracic muscle area is associated with composite weaning failure in both younger and older ventilated patients.
- The point estimate for this association was larger in patients younger than 75 years, though the age interaction was not statistically significant after adjustments.
- The graded association warrants further prospective validation to confirm its clinical significance.
Abstract:
Background/Objectives: Whether the prognostic contribution of low skeletal muscle mass varies with age in ventilated patients is untested. We assessed whether the association between low computed tomography (CT)-derived thoracic muscle area and ventilator-liberation outcomes differs by age. Methods: This single-center retrospective cohort included 607 adults with pneumonia requiring invasive ventilation in the intensive care unit (ICU) between 2016 and 2021. Thoracic muscle area was quantified by deep-learning segmentation of the whole thoracic musculature (first to twelfth thoracic vertebra) on the chest CT obtained closest to ICU admission and normalized to the length of the thoracic spine (median offset 0 days; 86% within ±7 days, before or after); low thoracic muscle area was the sex-specific lowest quartile. The primary outcome was composite weaning failure (extubation failure, tracheostomy, or ventilation >21 days). Multivariable logistic regression stratified at 75 years tested a muscle-area-by-age interaction. Results: Composite weaning failure occurred in 290 patients (47.8%). In fully adjusted complete-case models (n = 539), low thoracic muscle area was associated with composite weaning failure in younger patients (adjusted odds ratio 3.63; 95% CI 1.67-7.87) but not significantly in older patients (1.68; 0.91-3.13); the age interaction was not significant (p = 0.061) and was removed by height-normalization and by correction for multiple comparisons. A graded association across muscle-area quartiles was present in both strata (lowest vs. highest quartile: younger 4.79, older 2.53). Low thoracic muscle area was not associated with ICU mortality in either stratum, although an exploratory landmark analysis showed higher 7-day mortality in younger patients with low muscle area (20.6% vs. 10.8%). Conclusions: Low CT-derived thoracic muscle area was associated with composite weaning failure in both age strata, with a larger point estimate in patients younger than 75 years, although the age interaction was not significant in the fully adjusted model and was removed by height-normalization and by correction for multiple comparisons. The graded association in both age strata is hypothesis-generating and requires prospective validation.
