Acute mesenteric ischemia is a life-threatening condition caused by sudden interruption of blood flow to the intestine. It has a high mortality rate of 60-80% if not treated promptly. The mesentery was recently recognized as a new organ. Diagnosis involves imaging studies like CT angiography to identify blockages or narrowing of mesenteric arteries. Initial management focuses on resuscitation, antibiotics, and pain control. Definitive treatment involves surgical exploration to assess bowel viability, identify the cause, perform revascularization if possible, and resect non-viable bowel. Prognosis depends on factors like age, time to treatment, and extent of necrosis - outcomes are better if revascularization is done within

1. Approach and management of
Acute mesenteric ischaemia
Dr shambhavi sharma
1st year Resident
PAHS

2. • On 3rd January 2017, The Mesentery has been declared as a New
Organ and has been published in The Lancet Medical Journal(The
Lancet Gastroenterology & Hepatology) by J Calvin Coffey, a
researcher at the University Hospital Limerick, Ireland
• Gray’s Anatomy has already been updated with the definition.

4. Acute Mesenteric Ischaemia
• a catastrophic abdominal emergency
• characterized by sudden critical interruption to the intestinal blood flow
• commonly leads to bowel infarction and death
• uncommon but life-threatening disease
• Incidence ~1 in every 1000 hospital admissions
• Mortality remains as high as 60-80%
• Prognosis is poor
• Mark et al Semin Vasc Surg 23:9-20 ,2010

6. Areas prone to ischemia
• the watershed areas between the major vessels that supply the colon
are at risk for ischemia
• Narrow terminal branches of the SMA supply the splenic flexure,
• narrow terminal branches of the IMA supply the rectosigmoid
junction.

7. Splenic flexure –
• Griffiths' point :
• the site of communication of the ascending left
colic artery with the marginal artery of Drummond
• anastomotic bridging between the right and left
terminal branches of the ascending left colic artery
Rectosigmoid junction –
Sudeck's point:
the descending branch of the left colic artery forms
an anastomosis with the superior rectal artery

10. Physiology and mechanism of ischaemia
Normal physiology
• The splanchnic circulation receives between 10 to 35 percent of cardiac
output
• capillary density within the intestinal vasculature is high compared with
other vascular beds
• intestinal oxygen extraction is relatively low
• The intestine is able to compensate for an approximately 75 percent reduction
in mesenteric blood flow for up to 12 hours without substantial injury

11. Intrinsic autoregulation of blood flow :
• direct arteriolar smooth muscle relaxation
• a metabolic response to adenosine and other metabolites of mucosal
ischemia
Extrinsic regulation :
• the sympathetic nervous system
• the renin-angiotensin axis
• release of vasopressin from the pituitary gland
Intestinal blood flow must be reduced by at least 50 percent from
the normal fasting level before oxygen delivery to the intestine

12. Pathophysiology
Ischemia(perfusion pressure < 30mmHg,mean MAP
<45
Mucosal barrier disruption Substantial protein-rich fluid loss
Release of bacteria, toxins, vasoactive substance hypovolemia
SIRS
MODS
Death

13. Clinical presentation
Early symptoms
• Severe Abdominal pain that is
out of proportion to physical findings
in 95% cases
• Prominent symptoms of GI
emptying
( nausea, vomiting , diarrhea )
• Post prandial pain (SMA
thrombosis)
• Waxing and waning pain (SMV
thrombosis)

14. Late symptoms
• Bloody diarrhea
• Abdominal distension
• Features of Peritonitis-
Fever
 Shock
 Tachycardia

17. Investigation
Complete blood count
Haemoconcentration
Leukocytosis (Neutrophilic)
ABG analysis
Metabolic acidosis
Lactic acidosis (in more advanced
case)
Other serum markers :
Raised amylase
ALP

18. X-ray abdomen
Gas in the
small bowel
Dilated bowel loops

19. Imaging
Bowel wall
edema and
thickening
Gas in portal vein

20. Doppler study
• Able to identify severe stenosis or total or partial occlusion and
velocity of blood flowing through the vessels
• Unable to detect emboli beyond the proximal main vessel
• Non-obstructive mesenteric ischaemia
partially occluded Artery

24. Angiography
• Gold Standard
• Non-invasive : CT-Angiography
Magnetic Resonance Angiography
Invasive : Catheter (Conventional Method)
Findings on Angiography: Filling defects
Stenosis or blockage

26. Risk for mortality
• Older age
• Elevated serum aspartate
aminotransferase
• Increased blood urea nitrogen
• Metabolic acidosis
• Significant co-morbidities and poor
performance status
• Intestinal necrosis
• Increased elapsed time to
laparotomy(24hr)
• When the colon involved
Aliosmanoglu I et al. Int Surg. 2013
Gupta PK et al. Surgery. 2011

27. • Symptoms >24hr=Mortality increases dramatically
• when <12h= Gut viability 100%
• 56% when 12~24hr
• 18% when >24hr
• Revascularization performed within 12 h from the onset of symptoms.
• Resection of non-viable bowel should be performed without delay
Aliosmanoglu I et al. Int Surg. 2013

28. INITIAL MANAGEMENT
• Gastrointestinal decompression
• fluid resuscitation
• hemodynamic monitoring and support
• correction of electrolyte abnormalities
Antibiotics — Broad-spectrum antibiotic therapy
Pain control — parenteral opioids

29. Anticoagulation
• systemic anticoagulation needed to prevent thrombus formation and
propagation
C/I: actively bleeding, as in ischemic colitis related to nonocclusive ischemia
• For those who require abdominal exploration, anticoagulation is typically
continued after surgery to prevent new thrombus formation

30. Definitive surgical exploration
• Approach : midline laparotomy
1.Assessment of bowel viability
2. Determination of underlying cause
3. Mesenteric revascularization
4. Resection of necrotic bowel
5. Second look laparotomy

31. Assessment of bowel viability
1. Clinical Judgment
• pink serosa
• visible peristalsis
• positive pulsations
• bleeding from cut edges
• 2. Doppler USG - hand-held Doppler(Detects anti-mesenteric
blood flow)
• 3. Fluorescein -Injection of IV Sodium fluorescein(1gm) and
inspection under Wood’s lamp (Viable bowel has smooth,
uniform fluorescence)

34. Mesenteric Revascularization
• Embolism : Balloon catheter embolectomy ± Vein patch angioplasty
• Thrombosis : Thrombectomy
Bypass grafting
Reimplantation of SMA

35. Resection and anastomosis

36. Second look surgery
• Planned second look techniques are required after restoration of SMA flow,
with or without resection of ischemic bowel following resuscitation in intensive
care unit
• Given frequent uncertainty with regard to bowel viability, the stapled off bowel
ends should be left in discontinuity and re-inspected after a period of
continued ICU resuscitation to restore physiological balance.
• Often, bowel which is borderline ischemic at the initial exploration will improve
after restoration of blood supply and physiologic stabilization

37. • re-exploration should be accomplished within 48 h
• decisions regarding anastomosis, stoma, or additional resection can
be made with plans for sequential abdominal closure.

38. • Thank you

39. • Acute mesenteric ischemia: guidelines of the World Society of
Emergency Surgery 2017
• Sabiston text book of surgery
• Uptodate