Mesenteric Ischemia Flashcards
Results from
Acute
Chronic
Nonocclusive
Mesenteric Vein Thrombosis
restricted intest BF, reducing O2 delivery
A- arterial occlusion via embolus/thrombus (sudden hypoperfusion)
C- athero dec BF, leading to hypoperfusion in demand (dig/absorp)
N- systemic cx reducing CO (shock, HF) w spasm
MCT- thrombotic occlusion inc resistance in capillary beds- arterial hypoperfusion
Aterial blood to intestines
SMA to
IMA
Collateral blood supply for rectum/anal canal
marginal artery supplied by
most susceptible to ischemia
SMA/IMA
2nd part of duodenum to splenic flexure
splenic flexure to rectum
superior hemorrhoidal (IMA), middle rectal (Internal iliac artery)
SMA/IMA- supplies entire colon
watershed areas (splenic flexure/Griffiths) and (rs jxn (sudeks)
Prolonged ishcmia
even after blood flow is restored
mucosal necrosis begins, can lead to
After hypoperfusion, adequate BF
vascular bed vasoconstricts, reducing collateral flow
vc persists, worsen injury
full thickness ischemia/necrosis/perforation
causes reperfusion injury via ROS/PMNs (organ failure)
mcc type
Ischemic colitis occurs via
precipitating events
chronic mesenteric ischemia
nonocclusive hypoperfusion
hypoTN- aoroiliac sugery, CP bypass, MI, HF
CM of Ischemic colitis
full wall ischemia, pain becomes
ab ecam
continues to progress
full wall necrosis demonstrates
crampy ab pain (l side)- bright/maroon diarrhea
continuous/diffuse
more tenderness, absent bowel sounds
fluid shifts- dehydration, hypovol shock
met acid, inc serum lactate and leuko
Dx ischemic colitis
confirm dx w progressive sx
stable pt
colonoscopy w
mucosa appearance
clinical
surgical
colonoscopy
mimimal air insufflation to limit distension/pressure
pale, petechial bleeding/blue nodules (eventually cyanotic w hemorrhagic ulcers(
Mx ischemic colitis
administer
discontinue
full wall ischemia tx
supportive care- inc BP/volume
fluids IV
meds (Vasopressin/digitalis) promoting ischemia
surgical
Acute mesenteric ischemia occurs via
emboli can also lodge in
typically have hx of
emboli lodging at ponts of narrowing- distal to SMA (rarely IMA)
middle colic artery supplying mid jejunum (distant of IMA/celiac)
chronic mesenteric ischemia
Aterial embolism
Arterial thrombosis
Nonocclusive patterns of AMI
A fib, aneurysm, IE, MI
PAD, dissection, mycotic aneurysm
CP bypass, HF, shock, pressor
CM of AMI
exam findings
full wall ischemia
lab studies
sudden, severe ab pain- out of proportion to exam
mild TTP, bowel sounds, NV
pain constant/diffuse, more TTP, less bowel sounds, fluid shift
met acid, inc serum lact, leuko
Dx of AMI
sx of bowel infarct
gold standard dx
Mx
prognosis
clinical
surgical eval
CT angio
catheter based angio w tPA or thrombectomy
high morbid/mortality
Chronic mesenteric ischemia hx of
CM
crampy pain in
eventually
dx
management
smoking, PAD, CAD
intestinal angia- pain w eating
epigastric region- progressive
WL (lack of eating)
clinical, US, CT/MR angio for mesenteric stenosis
MVT bc of virchows
predisposing factors
stagnant BF, vasc injury, hypercoag
intra ab inflamm- panc/IBD, trauma (splenectomy), hypercoagulable (prothrombin mutation/ myeloprol, Protein C def)
MVT involves
Thrombotic occlusion of MV
fluid collects, leading to
w worsening
SMV w ileum/jejunm
inc resistance to MV bed, reducing perfusion
bowel wall edema, submucosal hemorrhage
IV pessure inc, diminishes arterial supply- ischemia/necrosis/perf
CM of MVT
bowel sounds/TTP/guarding
bowel infarction
dull/crampy pain, NV, distension
nroaml/absent
bowel sounds absent
