Introduction

’ terminal tissue perfusion, critically ill, stroke, edema, pulmonary edema, hypovolemia
CRITICALLY ILL, POSTOPERATIVE COMPLICATIONS, INFILTRATE, STROKE, EDEMA, PULMONARY EDEMA, PERIOPERATIVE COMPLICATION
Gastrointestinal surgery is a high-risk operation [Enhanced recovery after surgery (ERAS) protocols are increasingly widely used in the perioperative treatment and can greatly improve patient outcomes, shorten postoperative hospital stays, reduce perioperative complications, and decrease readmission rates to the hospital by 30–50% [Numerous observational studies have reported a strong association between both hypovolemia and overloaded intraoperative fluid infusion and an increased risk of postoperative complications [Adequate fluid intake to maintain cardiac output and blood pressure can ensure tissue perfusion, but it does not indicate a good state of microcirculation and tissue oxygenation. Therefore, static indicators cannot accurately guide fluid perfusion in the perioperative period. With the development of science and technology, dynamic indicators have been widely used in perioperative fluid management, such as stroke volume variation (SVV), and many good effects have been achieved [It is important to monitor not only systemic responses to fluid therapy but also microcirculation and homeostasis. However, research focusing on patients’ terminal tissue perfusion and oxygenation when receiving perioperative fluid management based on more advanced dynamic indicators is lacking. Plasma colloid osmotic pressure (COP) is an important factor in maintaining the balance of fluid flow between the extravascular and intravascular lumens. COP can inhibit the movement of water from intravascular to extravascular and allows interstitial fluid to infiltrate back into the blood vessels from the postcapillary venule, which plays an important role in stabilizing blood volume and preventing tissue edema. A report on pulmonary edema seems to indicate that the maintenance of a normal COP may be of greater importance in critically ill patients [