Background: Respiratory muscle strength affects pulmonary function after lung resection; however, the role of diaphragm density, an emerging index of muscle quality, remains unexplored. We investigated the role of crural diaphragm density (CDD) in respiratory complications (RC) after video-assisted thoracoscopic surgery (VATS) lobectomy for lung cancer.
Methods: A total of 118 patients were retrospectively enrolled between 2015 and 2022. Exclusion criteria were neoadjuvant therapy, thoracic trauma, and previous cardiothoracic and abdominal surgery. Demographic, functional, and radiological data were collected. The CDD in Hounsfield Unit (HU) was defined as the average of the density of the right and left crural diaphragm at the level of the median arcuate ligament on computed tomography axial images. RC included sputum retention, respiratory infections, atelectasis, pneumonia, respiratory failure, and acute respiratory distress syndrome.
Results: The prevalence of postoperative RC was 41% (48 of 118). RC occurred mostly in males (64.6 vs. 44.3%, p = 0.04), current smokers (41.7 vs. 21.4%, p = 0.02), a longer surgical procedure (210 vs. 180 minutes, p = 0.04), and a lower CDD (42.5 vs. 48 HU, p = 0.05). The optimal cutoff of CDD was 39.75 HU (sensitivity 43%, specificity 82%, accuracy 65%, area under the curve: 0.62, p = 0.05), slightly above the threshold for reduced muscle mass (<30 HU). By multivariable logistic regression a CDD ≤ 39.75 HU (hazard ratio [HR]: 3.134 [95% confidence interval, CI: 1.111-8.844], p = 0.03) and current smoking (HR: 2.733 [95% CI: 1.012-7.380], p = 0.05) were both independent risk factors of postoperative RC.
Conclusion: The CDD seems to be a simple and useful tool for predicting RC after VATS lobectomy, especially among current smokers. Such patients, identified early, could benefit from preoperative functional and nutritional rehabilitation.
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