Transcervical minimally invasive esophagectomy: hemodynamic study on an animal model.

BACKGROUND: Transcervical esophagectomy is a less invasive procedure performed within mediastinum. However, the mediastinum offers limited surgical space and the surgery via this route differs from conventional minimally invasive esophagectomy. Therefore, the physiological study of this surgical approach on an animal model would be necessary before the procedure gained more popularity.

METHODS: We conducted transcervical minimally invasive esophagectomy on animal model (swine) under CO2 pneumomediastinum. The hemodynamic parameters were monitored using float catheter cannulated via right jugular vein. At different anatomical level (the upper, middle, and lower thoracic part of the animal esophagus), increased artificial pneumomediastinal pressures (0, 4, 8, 12, and 16 mmHg) were consecutively allocated to record the intra-operative changes of blood pressure, cardiac output (CO), central venous pressure (CVP), pulmonary artery pressure (PAP) and extravascular lung water (EVLW). Meanwhile, the surgical field under different pneumomediastinum pressure was recorded and balanced with animals' hemodynamic changes to determine the optimal pressure for transcervical minimally invasive esophagectomy.

RESULTS: The animal procedures were accomplished without conversions. During the upper thoracic stage, increased CO2 pressures did not lead to significant changes in hemodynamic parameters including the blood pressure, CO, CVP, PAP or the level of EVLW. During the middle thoracic stage, pneumomediastinum under 4-12 mmHg did not lead to significant changes in hemodynamic parameters. However, pneumomediastinum at 16 mmHg resulted in lower CO (P=0.038) when compared to 0-12 mmHg. During lower thoracic stage, as the pneumomediastinum pressures increased from 0 to 16 mmHg, significant decrease in CO (P=0.022), and increase in CVP (P=0.036) was recorded. In compared to 4 mmHg pneumomediastinum, the surgical field under 8-16 mmHg artificial CO2 pneumomediastinum was suitable for mediastinal manipulation.

CONCLUSIONS: During transcervical minimally invasive esophagectomy on animal model, the mobilization of swine thoracic esophagus with optimal pneumomediastinum pressure 8-12 mmHg is safe and effective based on hemodynamic analysis.