Ischemic Colitis Flashcards
Ischemic colitis (IC)
when the blood supply to colonocytes does not meet metabolic demands
What is the most common cause of gastrointestinal (GI) ischemia.
Ischemic Colitis
describe the injury Types and complications
- at the initial incident of decrease in blood flow phase and/ or after reperfusion.
- If the injury occurred only at the mucosa, it can be reversible.
- Transmural injury can present as a life-threatening condition that can lead to stricture formation, perforation, sepsis, and death.
Which Sites are more prone to ischemia
- Griffith’s point, at the splenic flexure,
- Sudek’s point, at the rectosigmoid junction
- compromising 80% of IC cases.
Risk Factors
- age > 60
- higher prevalence in women
- commonly occurs after aortic or cardiac surgeries.
- peripheral artery occlusive disease
- coronary artery disease
- heart failure
- chronic obstructive pulmonary disease
- inflammatory bowel disease (IBD).
- cigarette smokers, both current and former
- diuretics or digoxin and psychotropic medications within the past month
high-risk, or “watershed,” areas ?
- regions in the colon between two major arteries
- Splenic flexure is the area between the SMA and the IMA arterial supply
- Rectosigmoid junction is the region between the IMA and the superior rectal artery supply.
- Rectosigmoid mostly supplied by the marginal artery; however, in 50% of the population, this artery is poorly developed.
During aortic surgery, ensure what ?
- The left colon has adequate blood supply if the IMA is acutely sacrificed
IC classified according to the mechanism of decreased blood flow to the colon
- Most commonly nonocclusive
as in cases of shock, drugs, and colon obstruction - Less commonly
after a vascular insult, due to an arterial thrombosis, embolism, or even a venous occlusion
special entity
> postoperative IC
after cardiac and vascular surgeries
intraoperative temporary cessation of blood flow to the colon.
For example, following abdominal aortic aneurysm repair or bypass, if the IMA was sacrificed or if there was prolonged cross clamp time
Time to develop the injury
- Mucosal injury will develop in 20 minutes to 1 hour of decreased blood flow
- Transmural infarction occurs within 8 to 16 hours.
- Additional insult occurs when blood flow is reestablished
Reperfusion injury causing more injury why ?
- Associated with the release of reactive oxygen species, which causes lipid peroxidation within cell membranes and leads to cell necrosis
Classification
- mucosal vs. transmural
- mild, moderate, and severe
Severe> transmural infarcts of the colon wall
leads to peritonitis, sepsis, perforation, and death.
- Anatomic location or distribution: segmental colitis or sidedness.
isolated right-sided colon ischemia (IRCI)
- Associated with poor outcomes
- 30-day mortality rate of 20.3%
- Higher frequency of severe cases requiring surgical intervention
- Associated with acute mesenteric ischemia.
- Associated more frequently in patients with coronary artery disease and chronic kidney disease on hemodialysis.
Pancolitis and IRCI
- Seen frequently in patients with sepsis
Presentation
> vague
diagnosis is often delayed
most common symptoms acute onset abdominal pain, hematochezia, and an urgent desire to defecate.
Gangrenous colitis and fulminant colitis
- Gangrenous > increasing abdominal tenderness, guarding, rebound tenderness, rising temperature, and paralytic ileus.
- The sudden onset of a toxic colitis with signs of peritonitis and a rapidly progressive course > fulminant colitis, > rare variant of IC.
Rectal bleeding is found more frequently in
non-IRCI
important for patient survival in IRCI
- Timely diagnosis of IRCI
Labs Inv
- Leukocytosis
- Elevated lactate, urea, and creatinine
- Metabolic acidosis and a base deficit in cases of severe ischemia, gangrene, and sepsis.
- Decreased hemoglobin levels, low serum albumin, and the presence of metabolic acidosis can be used to predict severity of IC.
Imaging
> CT scan
abdominal x-ray
> Classic findings on an x-ray include thumbprinting, which indicates mucosal edema.
In cases of bowel perforation, an x-ray is a quick way to see free air under the diaphragm.
CT Features
- can exclude other causes
suggest a location and source of ischemia
and identify complications - bowel wall thickening
- thumbprinting
- pericolonic stranding with or without ascites
- After reperfusion, > submucosal edema or hemorrhage
- Emboli or thrombi causing complete arterial occlusion > thin, unenhancing colonic wall due to complete lack of reperfusion.
- colonic pneumatosis and portomesenteric venous gas can be used to predict the presence of transmural colonic infarction
- Free Air, Bowel Perf
When to use splanchnic angiography
Patient with heralding sign of acute mesenteric ischemia (e.g., IRCI, severe pain without bleeding, and atrial fibrillation) and the multiphasic CT is negative for vascular occlusive disease.
Gold standard for confirming diagnosis
- Endoscopy > IC identified and biopsied
- Performed within 48 h of presentation
Features on Scope
- segmental erythema
- edema
- mucosal ulceration
- submucosal hemorrhagic nodules
- and involvement of watershed areas
- pseudomembranes related to mucosal sloughing
- colonic single stripe sign, a single linear ulcer running longitudinally along the antimesenteric colonic
- After 48 hours > sloughing occurs, the purple submucosal hemorrhages dissipate, and ulcerations develop.
- In more severe ischemia with transmural infarction, the mucosa may appear gray-green or even black
On histologic examination
- mucosa with necrosis and sloughing of the surface epithelium
- loss of epithelium in the superficial aspects of the crypts (with or without ghosts of crypts)
- mucin depletion
- reactive changes in the residual crypt epithelium
- nuclear hyperchromasia
- increased mitoses
- paucity or complete absence of acute inflammatory cells
- hyalinosis in the lamina propria
Mild to Mod Disease Tx
- supportive care
- bowel rest
- intravenous fluids
- optimizing cardiac output
- avoiding medications like vasopressors
- correction of electrolytes
- nasogastric tube decompression for ileus.
- intravenous antibiotics > treat bacterial translocation > both aerobic and anaerobic pathogens > recommended 2 weeks.
When to Consider Surgical Intervention
Hr > 100
SBP < 90
Hgb < 12
hyponatremia < 136
LDH > 450
blood urea nitrogen > 28 mg/ dL
A pancolonic distribution of disease and IRCI also portend a poor outcome.
Surgical intervention should be considered in the presence of IC accompanied by
hypotension
tachycardia
abdominal pain without rectal bleeding > IRCI and pancolonic IC
presence of gangrene.
acute setting, operative indications include
peritonitis on examination
massive bleeding
fulminant colitis
portal venous gas or pneumatosis on imaging with clinical picture of IC
worsening clinical condition
General principle of surgery
- Remove all segments of the colon that are grossly ischemic
- midline laparotomy or diagnostic laparoscopy
- it can be difficult to determine the extent of resection as the serosa
> preoperative CT scan
> Endoscopic evaluation
Intraoperatively
> Doppler ultrasonography
> endoscopy
> photoplethysmography to assess mucosal viability or colonic blood flow.
- concern for ongoing ischemia
> leave the fascia open and bowel in discontinuity
> intensive care unit for continued resuscitation
> second-look laparotomy and closure in 12 to 48 hours
The decision to construct an anastomosis versus an ostomy
> main concern is anastomotic leak or nonhealing anastomosis
> A primary anastomosis can be done safely in uncomplicated isolated right colon ischemia
> For left-sided IC > opinion advocates for an end colostomy and rectal stump (Hartmann procedure) > reversed later after 6– 8 weeks postsurgery
> In selected cases, it may be reasonable even with left-sided disease to perform a primary anastomosis with or without a protective diverting loop ileostomy.
complications Post Op
pneumonia
urinary tract infections
atrial fibrillation
postoperative myocardial infarction
acute renal failure
Hemodialysis
Independent risk factors of mortality after emergent colectomy for IC
- elderly age
- poor functional status
- multiple comorbidities
- ejection fraction < 20%
- preoperative septic shock
- preoperative blood transfusions
- preoperative acute renal failure
- delay from hospital admission to surgery
- Postoperative death is associated with the peak preoperative lactate level (if above 2.5 mmol/ L)
- amount of intraoperative blood loss
- pre- and intraoperative catecholamine administration,
- subtotal or total colectomy
- need for dialysis postoperatively
- (ASA) class 4.
Operative intervention for sequelae of IC
- symptomatic colonic strictures
- ostomy reversal.
- facial dehiscence
- wound complications.
Stricture Post IC
- colonoscopy
- contrast enema :
> helpful to describe the length and location of the stricture.
If clinically significant > obstruction or severe abdominal pain > elective resection and primary anastomosis.
Alternatively > balloon dilation, and stenting.
