Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality. The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality. The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Role of Multidetector Computed Tomography in Patients of Acute Mesenteric Ischaemia and its Comparison with Clinicosurgical Outcome: A Cross-sectional Study

Introduction: Acute mesenteric ischaemia is an abdominal emergency occurring in nearly 1% of patients presenting with acute abdomen. Early diagnosis is very important for the improved survival of the patient. Acute mesenteric ischaemia frequently presents with non specific features such as vomiting, loose stools and abdominal distension. The classical triad of fever, haematochezia and abdominal pain is seen in only 30% of the patients so, it is difficult to diagnose clinically. Multidetector Computed Tomography (MDCT) is gold standard and first line test to diagnose intestinal ischaemia. Aim: To assess the efficacy of MDCT in the diagnosis of acute mesenteric ischaemia and to compare its outcome with surgical and/or clinical findings. Materials and Methods: In this cross-sectional descriptive study conducted from 1st November 2018 to 31st May 2020, MDCT was performed on 40 patients (23 male; 17 female, age range: 28-93 years). Axial and reconstructed images of each patient were evaluated for evidence of bowel wall thickening, bowel wall attenuation, abnormal wall enhancement, bowel dilatation, mesenteric stranding, ascites, solid organ infarcts, pneumatosis intestinalis or portomesenteric gas, and mesenteric arterial or venous thrombosis. Multidetector CT findings were compared with the surgical findings and clinical outcome. Results were expressed in terms of frequency and percentages. Results: Out of 40 patients, most common cause of acute mesenteric ischaemia was arterial thrombosis, seen in 20 patients (50%) while 13 patients (32.5%) had portomesenteric venous thrombosis and 7 (17.5%) patients were diagnosed with non occlusive mesenteric ischaemia. CT finding of bowel wall thickening and bowel dilatation however non specific were seen in majority of patients (62.5% and 70%, respectively). Mesenteric fat stranding and ascites were seen in 95% and 77.5% cases respectively. Specific signs of acute mesenteric ischaemia includes hypoenhancing and non enhancing bowel walls seen in 27 patients (67.5%). Pneumatosis intestinalis and portomesenteric pneumatosis in 20% patients. A total of 27 patients underwent surgery and 13 patients were managed conservatively. On comparing the CT findings with intraoperative/ histopathological findings, accuracy of MDCT in the diagnosis of acute mesenteric ischaemia in this study was 96.39%. Conclusion: MDCT should be the first line imaging modality to diagnose acute mesenteric ischaemia and to exclude other causes of acute abdomen. It is an excellent and fast modality to diagnose bowel ischaemia, as it can visualise both the bowel and mesenteric changes as well as accurately depict the mesenteric vasculature.

Multidisciplinary diagnostic and therapeutic approach to acute mesenteric ischaemia: A case report with literature review

Superior mesenteric artery embolisation is the most common cause of acute mesenteric ischaemia. Superior mesenteric artery embolisation can be caused by various cardiac diseases (myocardial ischaemia or infarction, atrial tachyarrhythmias, endocarditis, cardiomyopathies, ventricular aneurysms and valvular disorders), arterial aneurysms, ulcerated atherosclerotic plaques of the major arteries and others. A case of 65-year-old, previously healthy man with superior mesenteric artery embolism, who was found to also have mural aortic thrombi, is presented. The patient underwent an emergency procedure; small intestine and cecum were resected and jejuno-ascendo anastomosis was performed. The patient was put on lifelong anticoagulation therapy. Neither cardiac diseases nor arterial aneurysms were detected. There were no signs of underlying atherosclerosis. Work-up for antiphospholipid antibodies and rheumatic diseases was negative. Tumour markers were within normal levels and blood cultures were negative. This case represents the challenges in recognising an underlying cause of acute mesenteric embolism and highlights the importance of multidisciplinary diagnostic and treatment approach.

Early detection and Successful Management of Acute Mesenteric Ischaemia in symptomatic COVID 19 patient

Newer evidence states that COVID 19 pneumonia induces a hypercoagulable state leading to vascular and microvascular thrombotic events. Acute mesenteric ischemia (AMI) is a potentially fatal vascular emergency with overall mortality of 60% to 80%. [1] However till date, only few cases of SMA thrombosis in COVID-19 positive patients are reported and most have succumbed to COVID-19 or mesenteric ischaemia. [2-4] Physicians treating COVID 19 usually treat respiratory symptoms and may completely overlook any other uncommon pathology. This case report emphasises that a patient with early detection and management of acute mesenteric ischaemia being symptomatic for COVID 19 can avoid major bowel surgery and negate any morbidity or mortality associated with the same.

Acute mesenteric ischaemia in refractory shock on veno-arterial extracorporeal membrane oxygenation

Background: Acute mesenteric ischaemia is a severe complication in critically ill patients, but has never been evaluated in patients on veno-arterial extracorporeal membrane oxygenation (V-A ECMO). This study was designed to determine the prevalence of mesenteric ischaemia in patients supported by V-A ECMO and to evaluate its risk factors, as well as to appreciate therapeutic modalities and outcome. Methods: In a retrospective single centre study (January 2013 to January 2017), all consecutive adult patients who underwent V-A ECMO were included, with exclusion of those dying in the first 24 hours. Diagnosis of mesenteric ischaemia was performed using digestive endoscopy, computed tomography scan or first-line laparotomy. Results: One hundred and fifty V-A ECMOs were implanted (65 for post-cardiotomy shock, 85 for acute cardiogenic shock, including 39 patients after refractory cardiac arrest). Overall, median age was 58 (48–69) years and mortality 56%. Acute mesenteric ischaemia was suspected in 38 patients, with a delay of four (2–7) days after ECMO implantation, and confirmed in 14 patients, that is, a prevalence of 9%. Exploratory laparotomy was performed in six out of 14 patients, the others being too unstable to undergo surgery. All patients with mesenteric ischaemia died. Independent risk factors for developing mesenteric ischaemia were renal replacement therapy (odds ratio (OR) 4.5, 95% confidence interval (CI) 1.3–15.7, p=0.02) and onset of a second shock within the first five days (OR 7.8, 95% CI 1.5–41.3, p=0.02). Conversely, early initiation of enteral nutrition was negatively associated with mesenteric ischaemia (OR 0.15, 95% CI 0.03–0.69, p=0.02). Conclusions: Acute mesenteric ischaemia is a relatively frequent but dramatic complication among patients on V-A ECMO.