Stroke volume variation (SVV) and pulse pressure variation (PPV) have been thought to be sensitive predictors of fluid responsiveness in mechanically ventilated participants. In this paper, the investigators reported a special group of people to use SVV and PPV during their operation. The maintenance of hemodynamic stability and the critical organ perfusion is crucial to the treatment for patients with artificial Pneumothorax during esophageal surgery, because artificial pneumothorax causes incomplete ventilation of one lung. In addition, artificial pneumothorax may seriously affect theparticipant's heart and lung function, brings more challenges to the intraoperative anesthetic management, expecially in volume management. Little information is available about the accuracy of SVV and PPV to predict fluid responsiveness in participants with artificial Pneumothorax during esophageal surgery. It is unclear whether it will affect the accuracy of SVV and PPV, and whether it will cause the change of their threshold values. The investigators will discuss it in the passage and the investigators will give an preliminary mechanism to explain the results.

Backgroud: This study aims to evaluate the ability of stroke volume variation (SVV) and pulse pressure variation (PPV) to predict fluid responsiveness in mechanically ventilated participants with artificial Pneumothorax during esophageal surgery.

Methods: 40 participants, diagnosed with esophageal cancer, undergoing thoracoscopic radical resection of esophageal cancer were studied. All the participants used Vigileo/FloTrac system for analysis. Haemodynamic data such as MAP, HR, SV, SVI, CO, CI, SVV, PPV were recorded before and after volume expansion (VE). Fluid responsiveness was defined as an increase in SVI≥10%(△SVI≥10%). Participants were divided into Responders and Non-responders by changes in △SVI ≥10% and < 10%. Nonparametric Wilcoxon rank sum test was used to compare the hemodynamic parameters of Responders and Non-responders before and after VE. Pearson correlation analysis was used to analyze the values of SVV, PPV and △SVI. The receiver operating characteristic (ROC) curve of each hemodynamic index was drawn to determine its accuracy and threshold.

Inclusion Criteria:

Must be arranged for thoracoscopic surgical treatment of esophageal cancer Must be mechanically ventilated with artificial Pneumothorax during the operation Must be normal in Allen test.

Exclusion Criteria:

Hypertension Coronary heart disease Arrhythmia Left ventricle ejection fractions < 50% (EF<50%) Pulmonary hypertension Congenital cardiovascular malformation Peripheral vascular disease Long-term history of oral vasoactive drugs

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