1. Retrospective analysis of perioperative data from patients undergone gastrointestinal surgery according to traditional practices from January to June 2015. Data about postoperative length of hospital stay, the morbidity and mortality of complications is collected from electronic database. The fluid was administrated according to the traditional method. Total intake volume = compensatory volume of expansion (CVE) + physically required volume+ cumulative loss volume + continued loss volume + the loss volume of the third space. Both physically required volume and cumulative loss volume were replaced according to 4-2-1 rule. Crystalloid and colloid were given with the ratio of 2/1. According to the bleeding, RBC and plasma were given if necessary. HR50 /min~100/min and MAP60~100mmHg were maintained during the surgery in both groups. When SBP<90 mmHg or MAP < 60 mmHg, the patients were given the vasoactive drug of bitartrate noradrenaline.