## 3 Colonic Ischemia After rAAA Repair  
In case of an rAAA, postoperative complications tend to be numerous and more frequent compared to elective treatments, whether through open surgical repair (OSR) or endovascular aneurysm repair (EVAR). These complications include pulmonary disorders, cardiac events, renal failure, lower-extremity ischemia, wound complications, and colonic ischemia. The incidence of these complications is higher after OSR than emergency EVAR [10]. Specifically, CI following an rAAA is strongly associated with perioperative hypotension, hypovolemic shock, the use of high-dose catecholamines, possible reperfusion injury, and embolic events [11; 12; 13]. [PERSON] et al. reported that a norepinephrine dosage > 64 \(\mu\)g/kg (RD 0.40, 95% CI: 0.25-0.55, \(p\) < 0.001) is a significant predictor of CI after an rAAA. Furthermore, ischemic colonic lesions were more frequently observed in patients with preoperative shock compared to those who were hemodynamically stable (20.7% vs. 4.2%, \(p\) < 0.05) [14]. Additionally, previous authors demonstrated that CI following EVAR is often attributed to systemic embolic events leading to bowel ischemia [15]. After the rupture of an AAA, a retroperitoneal hematoma may develop, and its severity is time-dependent. A retroperitoneal hematoma represents an abdominal space-occupying lesion, and the larger it is the greater the increase in intra-abdominal pressure, leading to the development of abdominal compartment syndrome. Moreover, the retroperitoneal hematoma contributes to the worsening of hypovolemia and hemorrhagic shock because of ongoing bleeding, coagulopathy, and the sequestration of liquids in the third space, necessitating resuscitation maneuvers with fluid therapy and transfusion of blood as well as blood components to stabilize the hemodynamic. However, it is necessary to limit fluid administration to reduce the risk of intestinal edema and ascites, which can further increase intra-abdominal pressure and exacerbate the development of abdominal compartment syndrome. If this syndrome is not promptly recognized and treated, it could lead to multi-organ failure, due to CI caused by visceral hypoperfusion, venous return compression, and intestinal traction [16; 17]. In the meta-analysis by [PERSON] et al., 101 studies with a total of 52,670 patients were analyzed, revealing a 10% prevalence of clinically relevant CI. The incidence reported across the studies was 3.9% following EVAR and 10% after OSR, with a relative risk (RR) of \begin{table}
\begin{tabular}{c|c|c|c|c|c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Risk Factor**}} & \multicolumn{3}{c}{**Relative Risk**} \\ \cline{2-6}  & **Very Low** & **Low** & **Moderate** & **High (Significantly** & **Very High** \\  & **(Minimal or** & **(Slight Increase in Risk)** & **(Average or** & **Increased Risk)** & **(Crtically** \\  & **Negligible Risk)** & & **Baseline Risk)** & **Increased Risk)** \\ \hline Age \textless{}70 year & \multicolumn{1}{c}{x} & & & \\ \hline Ruptured aneurysm & \multicolumn{1}{c}{x} & & & \\ \hline EVAR treatment & \multicolumn{1}{c}{x} & & & \\ \hline Male sex & \multicolumn{1}{c}{x} & & & \\ \hline Renal failure & \multicolumn{1}{c}{x} & & & \\ \hline Pulmonary history & \multicolumn{1}{c}{x} & & & \\ \hline Hypertension & \multicolumn{1}{c}{x} & & & \\ \hline Diabetes & \multicolumn{1}{c}{x} & & & \\ \hline Proximal extension of & \multicolumn{1}{c}{x} & & & \\ \hline the aneurysm & \multicolumn{1}{c}{} & & & \\ \hline Peripheral & \multicolumn{1}{c}{} & & & \\ \hline arterial disease & \multicolumn{1}{c}{} & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Semi-quantitative analysis of the main risk factors potentially associated with the development of CI after major aortic surgery, highlighted from the articles included in the present review. Background color intensity corresponds to the estimated level of risk, from minimal (green) to critically increased (red). x: reported association between the listed risk factor and colonic ischaemia. 1.8 [12].