Recommendations
Key Recommendations
Acute mesenteric ischaemia is a medical emergency. Urgent surgery is required if there is evidence on computed tomography scan of peritonitis, infarction, or perforation.
Liaise early with surgery and the intensive care unit.
Treatment involves a combination of resuscitation and supportive care, antibiotics, endovascular therapy (if there is no evidence of peritonitis, infarction, or perforation), or surgery.
The optimal approach will depend on the anatomical location and severity of ischaemia, its underlying pathophysiology, and time course.
Administer adequate fluid resuscitation and supplemental oxygen to optimise tissue perfusion and oxygenation.[20][38]
Check your local protocols for specific recommendations on fluid choice. There is debate, based on conflicting evidence, on whether there is a benefit in using normal saline or balanced crystalloid in critically ill patients.
Monitor controlled oxygen therapy. An upper SpO2 limit of 96% is reasonable when administering supplemental oxygen to most patients with acute illness who are not at risk of hypercapnia.
Evidence suggests that liberal use of supplemental oxygen (target SpO2 >96%) in acutely ill adults is associated with higher mortality than more conservative oxygen therapy.[48]
A lower target SpO2 of 88% to 92% is appropriate if the patient is at risk of hypercapnic respiratory failure.[49]
Initial resuscitation should also aim to address any acute heart failure and correct any cardiac arrhythmias.
Involve the critical care team for further management as necessary.
Consider invasive monitoring as appropriate. Nil by mouth status should be enforced, with nasogastric tube decompression for symptomatic relief.[8]
More info: Sepsis
Think 'Could this be sepsis?' based on acute deterioration in an adult patient in whom there is clinical evidence or strong suspicion of infection.[50][51][52] See Sepsis in adults.
The patient may present with non-specific or non-localised symptoms (e.g., acutely unwell with a normal temperature) or there may be severe signs with evidence of multi-organ dysfunction and shock.[50][51][52]
Remember that sepsis represents the severe, life-threatening end of infection.[53]
Ischaemic bowel disease and bowel perforation can cause rapid deterioration into septic shock.[54] For this reason, the assessment of severity status and subsequent action should be upgraded according to patient need, and at least to the next NEWS score band.[54] There should be no avoidable delay in giving antimicrobials and achieving source control.[54] In practice, if computed tomography (CT) shows extensive ischaemia in a patient who is very frail or has significant comorbidities, palliative care may be the treatment of choice (rather than antibiotics and source control); this decision should always be made in discussion with a consultant.
Use a systematic approach (e.g., National Early Warning Score 2 [NEWS2]), alongside your clinical judgement, to assess the risk of deterioration due to sepsis.[50][51][55][56][52] Consult local guidelines for the recommended approach at your institution.
Arrange urgent review by a senior clinical decision-maker (e.g., ST3 level doctor in the UK) if you suspect sepsis:[54]
Within 30 minutes for a patient who is critically ill (e.g., NEWS2 score of 7 or more, evidence of septic shock, or other significant clinical concerns).
A patient is also at high risk of severe illness or death from sepsis if they have a NEWS2 score below 7 and a single parameter contributes 3 points to their NEWS2 score and a medical review has confirmed that they are at high risk.
Within 1 hour for a patient who is severely ill (e.g., NEWS2 score of 5 or 6) or within 1 hour of any intervention for suspected sepsis (antibiotics/fluid resuscitation/oxygen) if there is no improvement in the patient’s condition.
Follow your local protocol for investigation and treatment of all patients with suspected sepsis, or those at risk. Start treatment promptly. Determine urgency of treatment according to likelihood of infection and severity of illness, or according to your local protocol.[54][56]
In the community and in custodial settings: refer for emergency medical care in hospital (usually by blue-light ambulance in the UK) any patient who is acutely ill with a suspected infection and is:[52]
Deemed to be at high risk of deterioration due to organ dysfunction (as measured by risk stratification)
At risk of neutropenic sepsis.
Acute mesenteric ischaemia is a medical emergency. Liaise early with surgery and intensive care unit colleagues.
Patients with delayed presentation and abdominal signs of peritonitis or organ failure generally have a worse prognosis than patients without these clinical factors.[20] It may be appropriate to discuss palliative care options with the multidisciplinary team if the patient is unlikely to benefit from invasive procedures.[20]
Antibiotics
Consult your local antimicrobial guidelines to administer empirical antibiotics suitable for enteric coverage (e.g., a third-generation cephalosporin plus metronidazole in critically ill patients, or a fluoroquinolone-based regimen in patients with beta-lactam allergy such as ciprofloxacin plus metronidazole) to all patients who are being treated with curative intent. Ischaemia can lead to significant bacterial translocation due to damage to the normal intestinal mucosal barrier.[8][57]
Antibiotics may not be indicated if a palliative treatment pathway is being followed.
Practical tip
Drug safety alert
Systemic fluoroquinolone antibiotics may cause serious, disabling, and potentially long-lasting or irreversible adverse events. This includes, but is not limited to: tendinopathy/tendon rupture; peripheral neuropathy; arthropathy/arthralgia; aortic aneurysm and dissection; heart valve regurgitation; dysglycaemia; and central nervous system effects including seizures, depression, psychosis, and suicidal thoughts and behaviour.[58]
Prescribing restrictions apply to the use of fluoroquinolones, and these restrictions may vary between countries. In general, fluoroquinolones should be restricted for use in serious, life-threatening bacterial infections only. Some regulatory agencies may also recommend that they must only be used in situations where other antibiotics, that are commonly recommended for the infection, are inappropriate (e.g., resistance, contraindications, treatment failure, unavailability).
Consult your local guidelines and drug formulary for more information on suitability, contraindications, and precautions.
Endovascular treatment
With the emergence of interventional radiology, consider endovascular treatment for haemodynamically stable patients where available. Options include thrombolysis, transjugular intrahepatic portosystemic shunt, and thrombectomy.[8][9][20] Endovascular therapy for acute mesenteric ischaemia has been shown to be associated with a reduced mortality and reduced risk of small bowel resection, though duration of patency may be shorter.[59][60][61][62][63] However, endovascular treatment is unlikely to be appropriate in a patient determined to have evidence of peritonitis.
Peritonitis, infarction, or perforation
If there are clinical signs of peritonitis, or radiographic or laboratory evidence suggesting infarction or perforation, proceed urgently with exploratory laparotomy and include resection of non-viable intestine.[8][38] Ideally, revascularisation procedures should be completed prior to any bowel resection, as borderline ischaemic bowel may recover satisfactorily after revascularisation. Second-look operations may be necessary to evaluate progression of ischaemia or reperfusion injury resulting in non-viable intestine requiring resection. Anastomosis can at times be delayed until the second-look laparotomy, especially if the patient is clinically unstable.
Depending on the underlying pathology and findings at surgery, several interventions may be appropriate.
Consider revascularisation with embolectomy or thrombectomy at the level of arterial occlusion for proximal embolisation or thrombosis.
Consider systemic-mesenteric bypass if arterial occlusion is due to severe and widespread atherosclerotic disease and the patient is stable enough to tolerate increased operative duration.
If mesenteric venous thrombosis is identified at the time of exploratory laparotomy, anticoagulation with intravenous heparin should be started (and continued until bowel function has normalised).[64] Venous thrombectomy may also be appropriate.[64]
If vasculitis is identified as a contributory cause (e.g., by thickened blood vessels on computed tomography scan, or the presence of other vasculitic symptoms, or a previous diagnosis) postoperative corticosteroid therapy may be considered.
If a source of sepsis is identified, use appropriate swabs and cultures to identify causative organisms and allow subsequent targeting of antibiotic therapy. See the More information box in Resuscitation and supportive measures; see also Sepsis in adults.
Post-operative anticoagulation is generally recognised as being beneficial, although timing of treatment is controversial. Some authorities recommend a delay of 48 hours following surgery because of the risk of intraluminal bleeding from damaged bowel, while others advocate immediate anticoagulation. Another suggested approach has been immediate anticoagulation if no infarction is present at surgery, and delayed anticoagulation if intestinal infarction is found. Good data on these approaches are lacking.[32]
Fulminant ischaemic colitis
Patients with fulminant ischaemic colitis usually appear acutely unwell and are unresponsive to medical therapy.
Ischaemia and necrosis of the right-side colon may be treated by right hemicolectomy with primary anastomosis, providing the remaining ileal and colonic ends are well perfused. If there is perforation and peritonitis, resection with terminal ileostomy and a colonic mucocutaneous fistula is indicated. Damage control surgery is another option; this involves resecting the ischaemic bowel and planning a second look with possible anastomosis 24 to 48 hours later.
Left-sided colonic involvement may require a proximal end stoma and distal mucous fistula or Hartmann's procedure. If most of the colon is ischaemic, subtotal colectomy with terminal ileostomy is indicated.
Depending on the findings of the initial surgery, a second-look operation within around 24 hours to reassess bowel viability may be indicated.
Superior mesenteric artery (SMA) embolus causes a critical reduction in flow of both the obstructed and unobstructed branches of the SMA. If not corrected promptly this will progress to infarction.
If available and the clinical condition of the patient permits, consider endovascular treatment as a first-line option.
Refer to the vascular team and a vascular radiologist.
Consider local thrombolytic therapy if there is no evidence of infarction, perforation, or peritonitis requiring urgent surgical intervention (and there are no contraindications). If lysis of the embolus cannot be demonstrated within 4 hours, or there is evidence of ischaemia progression, patients should undergo exploratory laparotomy with a view to conventional surgical embolectomy.
The open alternative is SMA embolectomy or arterial bypass. If not amenable to embolectomy, arterial bypass may be required. Any infarcted bowel should be resected.
Patients will generally be maintained on an intravenous heparin infusion once a diagnosis of SMA embolus is established. A heparin infusion titrated to therapeutic dosing following partial thromboplastin time (PTT) prolongation to 1.5 to 2.5 times normal PTT levels is recommended.
Acute SMA thrombosis is suggested by the absence of collaterals on angiography; this necessitates immediate intervention.
Surgical procedures that may be used in these circumstances include antegrade and retrograde bypass grafting, aortic re-implantation of the SMA, and transarterial and transaortic mesenteric endarterectomy.[31][65]
Endovascular treatment is unlikely to be appropriate in a patient determined to have evidence of peritonitis.
Patients with SMA thrombosis and no evidence of infarction, perforation, or peritonitis will generally be maintained on an intravenous heparin infusion once a diagnosis of SMA thrombosis is established. A heparin infusion titrated to therapeutic dosing following partial thromboplastin time (PTT) prolongation to 1.5 to 2.5 times normal PTT levels is recommended.
The presence of collaterals on angiography suggests a chronic SMA thrombosis. In this case endovascular treatment is the first-line therapy.
Options include angioplasty ± stenting, aspiration thrombectomy, or local drug instillation. If patients are unsuitable for endovascular intervention, surgery may be an option if the patient is fit enough. Refer to the vascular team and a vascular radiologist.
Surgical procedures that may be used in these circumstances include antegrade and retrograde bypass grafting, aortic reimplantation of the SMA, and transarterial and transaortic mesenteric endarterectomy.[31]
Timing of postoperative anticoagulation is controversial, although it is generally recognised as being beneficial.
For patients with SMA embolus or thrombosis and peritonitis, infarction, or perforation, see Peritonitis, infarction, or perforation above in Acute mesenteric ischaemia.
Non-occlusive mesenteric ischaemia (NOMI) is caused by splanchnic hypoperfusion, which may be precipitated by congestive heart failure, cardiac arrhythmia, or shock, or by large volume shifts, which can sometimes occur during haemodialysis.
Urgent correction of any underlying medical cause of hypoperfusion (e.g., heart failure) is of paramount importance to restore perfusion. After correction of the underlying medical condition, endovascular therapy is the first-line option, with selective mesenteric angiography and local intra-arterial infusion of vasodilators.[66] The infusion should be continued until there is no angiographic or clinical evidence of persistent vasoconstriction.
Laparotomy is indicated if there is evidence of peritonitis, perforation, or if the patient clinically declines.[20] Surgery should preserve bowel of questionable viability, unless necrosis is clear. With use of temporary abdominal closure and re-exploration at 24 to 48 hours after the first operation, intestinal resection can be kept to a minimum.
Anticoagulation is the first-line treatment option for venous mesenteric ischaemia when the clinical condition permits. This may be successful in up to 95% of cases. These patients need close clinical observation, and surgery is indicated if signs of peritonitis develop.
Therapeutic anticoagulation with intravenous heparin should continue until bowel function normalises.[64] In patients who receive heparin, the recurrence rate is lowered from 25% to 13% and mortality is reduced from 50% to 13%.[32] Once patients are stable, symptom-free, and able to tolerate oral medication, they can be converted to warfarin, which should then be administered for 3 to 6 months.
Surgery is indicated in patients with venous ischaemia when there are signs of infarction or peritonitis. Infarcted bowel should be resected.[64] A second-look procedure is a valuable tool to assess the recovery of any questionable segments of bowel that can be left in situ at the index surgery if potentially viable.[64]
If a mesenteric vein thrombus is discovered incidentally in an asymptomatic patient who undergoes a computed tomography scan for another reason besides abdominal pain, a 3- to 6-month course of warfarin is recommended, especially if a predisposing hypercoagulable state or concomitant deep vein thrombosis can be identified.[67]
The treatment of chronic mesenteric ischaemia will depend on several factors, most notably whether or not the patient is a surgical candidate.
Consider endovascular treatment, particularly in patients with severe malnutrition, as it is associated with less morbidity and mortality than open therapy.[68][69]
Practical tip
Malnutrition
The National Institute for Health and Care Excellence in the UK defines malnourishment as:[70]
A body mass index (BMI) of less than 18.5 kg/m2
Unintentional weight loss greater than 10% within the last 3 to 6 months
A BMI of less than 20 kg/m2 and unintentional weight loss greater than 5% within the last 3 to 6 months.
If the patient is assessed as suitable for open surgery after medical optimisation of any cardiovascular, respiratory, or other comorbidities, then surgical systemic-mesenteric bypass forms the mainstay of treatment, although other procedures may be used. Antegrade and retrograde bypass grafting, aortic re-implantation of the superior mesenteric artery, and transarterial and transaortic mesenteric endarterectomy all have a role.[31] Open surgery is better for long-term patency when compared with endovascular approaches for chronic mesenteric ischaemia.[68][71]
In patients who are not fit to undergo an open procedure, percutaneous transluminal mesenteric angioplasty alone or with stent insertion may be an option.[72]
This is the most common form of intestinal ischaemia and comprises a spectrum of disorders including:[73]
Reversible colonopathy
Transient colonic ischaemia
Chronic colonic ischaemia
Stricture
Gangrene
Fulminant pancolitis.
Most patients with colonic ischaemia do not have any identifiable, specific, and precipitating cause, and treatment varies with severity of presentation.[4] Most cases resolve spontaneously (reversible ischaemic colonopathy or transient colonic ischaemic changes). Patients with severe or continuing symptoms might need admission to hospital, supportive measures, bowel rest, and investigation and treatment of any underlying cause.
There are several indications for surgery in colonic ischaemia.[4]
Acute indications:
Peritoneal signs, suggestive of necrosis or perforation
Massive bleeding (rare): may require subtotal colectomy
Universal fulminant colitis with or without toxic megacolon.
Subacute indications:
Failure of an acute segmental ischaemic colitis to respond within 2 to 3 weeks, with continued symptoms or a protein-losing colonopathy
Apparent healing but recurrent bouts of sepsis.
Chronic indications:
Symptomatic colon stricture: may be treated with endoscopic balloon dilation or segmental resection
Symptomatic segmental ischaemic colitis.
Ischaemic colitis
Patients with colonic ischaemia can develop chronic ulcerating ischaemic colitis.[37] Seek gastroenterological and surgical input for ischaemic colitis.[36]
In mild cases, trial conservative management, including intravenous antibiotics, fluids (and blood glucose control in patients with diabetes), and bowel rest.
Consider nutrition support in patients at risk of malnutrition who:[70]
Have eaten little or nothing for more than 5 days and/or are likely to eat little or nothing for the next 5 days or longer
Have a poor absorptive capacity, and/or have high nutrient losses and/or have increased nutritional needs from causes such as catabolism.
Frequently review the patient, examining the abdomen and monitoring vital signs. Further investigations and imaging are required if symptoms do not resolve, symptoms worsen, or new symptoms appear.[36]
Prophylactic low molecular weight heparin is generally used. Secondary prevention with anticoagulation should be considered at the point of discharge.[36]
Surgical intervention for ischaemic colitis usually involves segmental resection and stoma formation.[36]
Non-acute colonic ischaemia
Patients who have an acute episode of colonic ischaemia that evolves into a segmental colitis pattern with symptoms persisting for >2 weeks, or who develop a protein-losing colonopathy, are usually best treated by segmental colectomy.[4]
Episodes of recurrent sepsis in a patient who has symptomatically recovered from an acute episode of colonic ischaemia may be an indication for surgery. These patients usually have a short segment of unhealed bowel that is the source of sepsis, and resection of the segment is usually curative.[4]
See Sepsis in adults.
Interventions such as endoscopic dilation of stricture or segmental resection should only be used if strictures are symptomatic. Transendoscopic dilation may be successful in less severe cases. Alternatively, segmental resection can be used.[4]
Patients with acute transient or mild ischaemia have physical findings with no evidence of peritonitis, intestinal perfusion, or full-thickness necrosis on a computed tomography scan or mesenteric angiography.
Use conservative measures if imaging suggests mucosal or submucosal involvement only. These include:
Nil by mouth status
Fluid resuscitation
Nasogastric tube decompression for symptomatic relief.
The underlying cause should be treated promptly. This may include:
Anticoagulation for mesenteric venous thrombosis[64]
Tailored antibiotic therapy when an infectious cause is identified
Corticosteroids for vasculitis
Fluid resuscitation and cardiac optimisation for shock (see Shock).
Frequently reassess the patient to detect patients in whom conservative management fails and who then require operative intervention due to evidence of peritonitis or infarction.
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