Factors influencing difficulty of the thoracic procedure in minimally invasive esophagectomy

Background: Minimally invasive esophagectomy (MIE) is being increasingly performed worldwide. When performing MIE, we sometimes experienced difficulties due to a narrow upper mediastinum or a middle to lower thoracic esophagus hidden by the projection of the vertebral body. However, there were no reports regarding the influence of anatomical factors on the difficulty of performing MIE. The aim of this study was to evaluate whether anatomical factors could be related to the difficulty of the thoracic procedure in MIE. Methods: We investigated 87 consecutive patients undergoing MIE for primary esophageal cancer between 2013 and 2015 and created novel indices to assess the upper mediastinal narrowness and vertebral body projection at middle thoracic part on preoperative computed tomography images. We assessed clinicopathological and anatomical factors and determined the factors influencing the thoracic procedural difficulty in MIE. The thoracic procedure duration was selected as the variable representing technical difficulty. Results: The mean thoracic procedure duration was 280.2 ± 52.5 min. There were no significant correlations between the indices and patient factors such as age, sex, and body mass index. Meanwhile, there was a significant correlation between the upper mediastinal narrowness and the vertebral body projection (p < 0.01). Of the clinicopathological and anatomical factors, blood loss during the thoracic procedure, thoracic duct resection, and vertebral body projection independently were related to the prolonged thoracic procedure duration in multiple linear regression analysis (p = 0.01, 0.03, and <0.01, respectively). The other factors including upper mediastinal narrowness were not statistically significant. Conclusions: This is the first study to reveal the influence of anatomical factors on the difficulty of the thoracic procedure in MIE. The vertebral body projection at middle thoracic part appears to be a useful tool for predicting the thoracic procedural difficulty in MIE preoperatively.