Atherosclerosis is associated with poorer outcome in non-occlusive mesenteric ischemia

Insights into acute mesenteric ischaemia: an up-to-date, evidence-based review from a mesenteric stroke centre unit

Radiologists play a central role in the diagnostic and prognostic evaluation of patients with acute mesenteric ischaemia (AMI). Unfortunately, more than half of AMI patients undergo imaging with no prior suspicion of AMI, making identifying this disease even more difficult. A confirmed diagnosis of AMI is ideally made with dynamic contrast-enhanced CT but the diagnosis may be made on portal-venous phase images in appropriate clinical settings. AMI is diagnosed on CT based on the identification of vascular impairment and bowel ischaemic injury with no other cause. Moreover, radiologists must evaluate the probability of bowel necrosis, which will influence the treatment options.AMI is usually separated into different entities: arterial, venous, non-occlusive and ischaemic colitis. Arterial AMI can be occlusive or stenotic, the dominant causes being atherothrombosis, embolism and isolated superior mesenteric artery (SMA) dissection. The main finding in the bowel is decreased wall enhancement, and necrosis can be suspected when dilatation >25 mm is identified. Venous AMI is related to superior mesenteric vein (SMV) thrombosis as a result of a thrombophilic state (acquired or inherited), local injury (cancer, inflammation or trauma) or underlying SMV insufficiency. The dominant features in the bowel are hypoattenuating wall thickening with submucosal oedema. Decreased enhancement of the involved bowel suggests necrosis. Non-occlusive mesenteric ischaemia (NOMI) is related to impaired SMA flow following global hypoperfusion associated with low-flow states. There are numerous findings in the bowel characterised by diffuse extension. An absence of bowel enhancement and a thin bowel wall suggest necrosis in NOMI. Finally, ischaemic colitis is a sub-entity of arterial AMI and reflects localised colon ischaemia-reperfusion injury. The main CT finding is a thickened colon wall with fat stranding, which seems to be unrelated to SMA or inferior mesenteric artery lesions. A precise identification and description of vascular lesions, bowel involvement and features associated with transmural necrosis is needed to determine patient treatment and outcome.

Increased blood lactate during enteral nutrition in the critically ill: associations and treatment options

PURPOSE OF REVIEW

To evaluate the significance of blood lactate increase during enteral nutrition in the critically ill, and to propose diagnostic and therapeutic strategies.

RECENT FINDINGS

Acute mesenteric ischemia occurs in approximately 1% of critically ill patients treated with catecholamine. Recent literature suggests that enteral nutrition is a risk factor of acute mesenteric ischemia, in particular in case of low cardiac output, by a mechanism of nonocclusive mesenteric ischemia. The association of clinical, biological, and computed tomography imaging might help to evaluate the reversibility of acute mesenteric ischemia.

SUMMARY

As enteral nutrition induces an increased metabolic work of the gut, the inadequation between oxygen delivery and demand exposes the gut to a phenomenon of nonocclusive mesenteric ischemia. Before initiation of enteral nutrition,, and before each increase of the enteral nutrition dose, the risk factors of nonocclusive mesenteric ischemia should be searched in order to prevent it. While under enteral nutrition, increased lactate concentration while receiving enteral nutrition requires the urgent search for nonocclusive mesenteric ischemia, and the adaptation of enteral nutrition (reduction, stop, and/or switch to parenteral nutrition or tolerate early nutrient restriction). Early signs of nonocclusive mesenteric ischemia should be searched in order to allow for a rapid diagnosis, before development of irreversible transmural necrosis. After the diagnosis of acute mesenteric ischemia, improving the balance between oxygen demand and delivery to the gut, evaluating the reversibility of the gut ischemia, and performing urgent resection in case of irreversible transmural necrosis should be the main objectives. After the resolution of acute mesenteric ischemia, the benefit risk analysis of enteral nutrition reintroduction should be evaluated.

Abdominal atherosclerosis is not a risk factor of nonocclusive mesenteric ischemia among critically ill patients: a propensity matching study

BACKGROUND

Although risk factors of occlusive acute mesenteric ischemia are well known, triggering factors of nonocclusive mesenteric ischemia (NOMI) remain unclear. Alongside to the known risk factors for NOMI, the role of atherosclerosis is not fully elucidated. The purpose of our study was to evaluate whether abdominal atherosclerosis is a risk factor for NOMI.

METHODS

From January 2018 to December 2021, all consecutive patients admitted to the intensive care unit who underwent contrast-enhanced CT for suspicion of NOMI were evaluated for inclusion. Clinical and biological data at the time of the CT scan were retrospectively extracted from medical charts and reviewed by a single radiologist. The cohorts were matched by a 1:1 propensity score based on the patient clinical, biological data, and abdominal CT features associated with NOMI. Noncontrast CT acquisitions were used to calculate calcium scores of the abdominal aorta, celiac trunk, superior mesenteric artery (SMA), and common iliac artery according to the Agatston method. Analyses were performed before and after propensity score matching.

RESULTS

Among the 165 critically ill patients included, 59 (36%) had NOMI. Before matching analysis, the SMA and total abdominal Agatston calcium scores were not different between patients without and with NOMI (52.00 [IQR = 0, 473] vs. 137.00 [IQR = 0, 259], P = 0.857, respectively, and 7253 [IQR = 1220, 21738] versus 5802 [IQR = 2075, 15,084]; P = 0.723). The results were similar after matching 38 patients with NOMI and 38 without: 153 [IQR = 0, 665] versus 85 [IQR = 0, 240] (P = 0.312) for the SMA calcium score, and 7915 [IQR = 1812, 21561] versus 4139 [IQR = 1440, 9858] (P = 0.170) for the total abdominal Agatston calcium score.

CONCLUSION

Our results suggest that atherosclerosis is not a risk factor for NOMI in critically ill patients.

Non-occlusive mesenteric ischemia (NOMI) and prognostic signs at CT: reperfusion or not reperfusion that is the question!

PURPOSE

Non-occlusive mesenteric ischemia (NOMI) is a misdiagnosed and dangerous condition. To our knowledge, a comprehensive evaluation of CT parameters that can predict the outcome of patients suffering from NOMI is still missing.

MATERIALS AND METHODS

Contrast-enhanced CT examination of 84 patients with a confirmed diagnosis of NOMI (37 with clinical and laboratory confirmation and 47 biopsy or surgery proven) was retrospectively reviewed by assessing vessels, mesentery, bowel, and peritoneal cavity CT quantitative and dichotomous parameters, and data were analyzed with Fisher's test. Diameter of superior mesenteric artery (SMA), celiac trunk (CT), inferior vena cava (IVC), superior mesenteric vein (SMV), and differences in CT HU (Delta HU) of the bowel wall before and after intravenous contrast media (ICM) administration were correlated to the patients' outcome using ANOVA test. Receiver operating characteristic (ROC) curves were elaborated after a binary logistic regression was performed.

RESULTS

Increased number and diameter of vessels, bowel wall thickening, and hypervascularity were more frequent in patients with good prognosis. Conversely, pale mesentery, paper thin, hypovascularity, and aeroportia were more frequent in patients with bad prognosis. A significant correlation between diameters of SMA, CT, IVC, IMA, and SMV and outcome was found at univariate analysis. Also Delta HU resulted to be correlated with the outcome. At multivariate analysis only IVC and Delta HU were significant (p = 0.038 and 0.01) and the combined AUC resulted in 0.806 (CI 0.708-0.903).

CONCLUSION

Dichotomous signs of reperfusion and quantitative CT parameters can predict the outcome of patients with NOMI. In particular the combination of IVC diameter and Delta HU of bowel wall allows to predict the prognosis with the highest accuracy.

Factors associated with acute mesenteric ischemia among critically ill ventilated patients with shock: a post hoc analysis of the NUTRIREA2 trial

PURPOSE

Acute mesenteric ischemia (AMI) is a rare, but life-threatening condition occurring among critically ill patients. Several factors have been associated with AMI, but the causal link is debated, most studies being retrospective. Among these factors, enteral nutrition (EN) could be associated with AMI, in particular among patients with shock. We aimed to study the factors independently associated with AMI in a post hoc analysis of the NUTRIREA-2 trial including 2410 critically ill ventilated patients with shock, randomly assigned to receive EN or parenteral nutrition (PN).

METHODS

Post hoc analysis of the NUTRIREA-2 trial was conducted. Ventilated adults with shock were randomly assigned to receive EN or PN. AMI was assessed by computed tomography, endoscopy, or laparotomy. Factors associated with AMI were studied by univariate and multivariate analysis.

RESULTS

2410 patients from 44 French intensive care units (ICUs) were included in the study: 1202 patients in the enteral group and 1208 patients in the parenteral group. The median age was 67 [58-76] years, with 67% men, a SAPS II score of 59 [46-74], and a medical cause for ICU admission in 92.7%. AMI was diagnosed among 24 (1%) patients, mainly by computed tomography (79%) or endoscopy (38%). The mechanism of AMI was non-occlusive mesenteric ischemia (n = 12), occlusive (n = 4), and indeterminate (n = 8). The median duration between inclusion in the trial and AMI diagnosis was 4 [1-11] days. Patients with AMI were older, had a higher SAPS II score at ICU admission, had higher plasma lactate, creatinine, and ASAT concentrations and lower hemoglobin concentration, had more frequently EN, dobutamine, and CVVHDF at inclusion, developed more frequently bacteremia during ICU stay, and had higher 28-day and 90-day mortality rates compared with patients without AMI. By multivariate analysis, AMI was independently associated with EN, dobutamine use, SAPS II score ≥ 62 and hemoglobin concentration ≤ 10.9 g/dL.

CONCLUSION

Among critically ill ventilated patients with shock, EN, dobutamine use, SAPS II score ≥ 62 and hemoglobin ≤ 10.9 g/dL were independently associated with AMI. Among critically ill ventilated patients requiring vasopressors, EN should be delayed or introduced cautiously in case of low cardiac output requiring dobutamine and/or in case of multiple organ failure with high SAPS II score.