Association between preoperative diaphragm thickening fraction and postoperative pulmonary complications in patients undergoing thoracoscopic esophagectomy for esophageal cancer

Objective: This study aimed to investigate the association between preoperative diaphragm thickening assessed using ultrasound imaging and postoperative pulmonary complications (PPCs) in patients undergoing thoracoscopic esophagectomy for esophageal cancer. Methods: This single-center, prospective, cohort study enrolled patients with esophageal cancer who were scheduled to undergo thoracoscopic esophagectomy between June 2021 and May 2024. The diaphragm thickening fraction (DTF) was measured using ultrasound imaging at preoperatively and 1 week and 2 weeks postoperatively. Our primary outcome comprised overall PPCs. We investigated the longitudinal change in the DTF and the relationship between the DTF and PPCs. We also examined the optimal cutoff value for the ability of the DTF to predict PPCs. Results: This study enrolled 73 patients. PPCs occurred in 21 (29%) patients, 10 (14%) of whom had pneumonia. The estimated difference between the preoperative and 1-week postoperative least squares means of the DTF was −56.3% (95% credible interval [CrI]: −65.4, −47.2) and −36.5% (95%CrI: −43.7, −29.2) between the preoperative and 2-week postoperative values. The mean relative risk (RR) of preoperative DTF to PPCs was 0.89 per 10% increase(95%CrI: 0.80, 0.99), after adjusting for potential confounders. In the posterior distribution, the probability that the RR of the DTF per 10% increase would be <1 was 98.0%. According to the receiver operating characteristic curve, the optimal cutoff value of preoperative DTF predicting PPCs was 123.6%. Conclusion: DTF is decreased 1 and 2 weeks after thoracoscopic esophagectomy in patients with esophageal cancer. The higher the preoperative DTF, the lower the risk of occurrence of PPCs.