Background: The respiratory muscles strength affects pulmonary function after lung resections, 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 VATS lobectomy for lung cancer.

Methods: 118 patients were retrospectively enrolled between 2010 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. The RC, including bronchospasm, respiratory infections, atelectasis, pneumonia, respiratory failure, and ARDS, were recorded according to the European Perioperative Clinical Outcome definitions [Jammer I, et al. Eur J Anesthesiol 2015;32:88-105].

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 48HU, p=0.05). The optimal cut-off of CDD was 39.75HU (sensibility 43%, specificity 82%, AUC0.62, p=0.05). By multivariable logistic regression a CDD?39.75HU [HR 3.134 (95%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.

Conclusions: The CDD seems to be a simple and useful tool for predicting RC after VATS lobectomy, especially among current smokers.