Correlation Between Acute Gastrointestinal Injury and Venous Return in Critical Ill Patients

Currently, altered intestinal blood flow in critically ill patients has been a hot research topic in recent years. In 2022, studies on acute mesenteric ischemia were published in top journals in critical care medicine \[Crit Care, 2022. 26(1): p.92. and Intensive Care Med, 2022. 26(2): p.92.\]. However, because the gastrointestinal tract is in the abdominal cavity and doctors lack methods to directly monitor the visceral perfusion. Therefore, there is little research on the relationship between gastrointestinal perfusion and acute gastrointestinal injury in critical ill patients. Currently, the diagnosis of acute gastrointestinal injury is mostly performed using subjective indicators and adverse outcomes that have already occurred, which results in the treatment of acute gastrointestinal injury often lagging behind. The use of color Doppler ultrasonography to assess blood flow in intestinal vessels in healthy and outpatient patients has been in use since the 1980s. Our team showed that the resistance index of the superior mesenteric artery(SMA) in postoperative cardiac surgery patients correlated with lactate values and lactate clearance \[Front Med (Lausanne), 2021.8: p.762376.\], suggesting that gastrointestinal perfusion as reflected by SMA blood flow is important for systemic resuscitation, and that Doppler indices of SMA have the potential value of reflecting intestinal hypo-perfusion. Intestinal venous blood enters the portal vein and then the liver before returning to the right heart via the inferior vena cava. Right ventricular dysfunction or abdominal hypertension could cause obstruction of portal venous return, which might lead to edema and dysfunction of the intestine. Therefore, monitoring the venous return status is crucial for intestinal perfusion. In 2012, the Venous Excess Ultrasound Score(VExUS) for evaluating venous return has been reported and it has been shown to correlate with acute kidney injury (AKI) \[Intensive Care Med, 2012. 38(3): p.384-94\]. However, there is currently no research on the correlation between acute gastrointestinal injury and venous return, and this study is innovative and exploratory.