Lecture 18- GI emergencies 2/2 Flashcards
Acute mesenteric ischemia
Symptomatic reduction in blood supply to GI tract
- Risk factors of acute mesenteric ischemia
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More common in females (75%) and if you have a history of peripheral vascular disease
causes of acute mesenteric ischaemia
- Acute occlusion (70%)
- Non-occlusive mesenteric ischaemia (20%)
Acute occlusion (70%)
Arterial embolism in the SMA (50%)- midgut
Non-occlusive mesenteric ischaemia (20%)
- Low CO
- Mesenteric venous thrombosis (5-10%)
- Systemic coagulopathy and malignancy
most cases of acute mesenteric ischaemia are in
lderly patients. With CVD risk factors.
- Symptoms of acute mesenteric ischaemia
- Can be difficult to diagnose because symptoms can be fairly non-specific
- Abdominal pain disproportionate to the clinical findings
- Classic pain- comes on 30 mins after eating and lasts 4 hours
- Nausea and vomiting
- Abdominal pain disproportionate to the clinical findings
- Can be difficult to diagnose because symptoms can be fairly non-specific
Pain on left hand side
- why Pain on left hand side in acute mesenteric ischaemia-
- blood supply to the splenic flexure (point where transverse colon turns into the descending colon) is more fragile
AMI Investigations
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- Blood tests
- Metabolic acidosis / increased lactate levels- ischaemic drugs
- Erect chest x-ray- check for perforation (gas under the diaphragm)
- CT angiography (90% sensitivity)- intravenous contrast
Treatment AMI
- Surgery- resection of ischaemic bowel–> bypass graft
- Thrombolysis/angioplasty
Prognosis of AMI
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- Mortality is high (arterial thrombosis’s up to 70% mortality)
- Often older pts with comorbidities
2 examples of major upper GI bleeding
- peptic ulceration
- oesophageal varices
peptic ulceration causes …….% of acute upper GI bleeding
20-50%
what is peptic ulceration
- Disruption in gastric/duodenal mucosa that extends through the muscularis mucosa
- Greater than 5mm diameter
which type of ulcer is most common
- Duodenal ulcers most common
- First part of duodenum
- Gastro-duodenal artery lies behind first part of duodenum
where are peptic ulcers found in the stomach
- Lesser curve and antrum common sites
gastric ulcer erosion is especially dangerous if it erosed the
splenic artery
what are oesophageal varices
porto-systmeic anastomosis
- 12-14% of acure upper GI bleeding
explain how oesophageal varices occur and how they can lead to major upper GI bleeding
- an example of porto-systemic anastomosis
- they are often caused by portal hypertension
- back flow of blood from the portal vein –> left gastric –> which drains the distal portion of the oesophagus
- oesophagus also draine dby the azygous vein
- left gastric vein and azygous anastomose
- these anastomes distend with blood – rupture –> bleed
causes of oesophageal varices
portal hypertension
- Caused by anything that slows blood flow through portal vein
- Pre-hepatic (portal vein thrombosis)
- Hepatic (cirrhosis schistosomiasis)
- Post hepatic causes (hepatic vein thrombosis, RHF)
- Normal pressure in portal vein
- 5-10mm Hg
- Problem happens around 10 mmHg
- porto-systemic anastomoses are areas that
have venous drainage through portal vein and systemic veins e.g. the distal portion of the oesophagus
Treatment of oesophageal varices
- Fluid resus
- If bleeding not controlled by banding
- Transjugular intrahepatic portosystemic shunt (TIPS)
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Drug treatment
- Terlipressin- reduces portal venous pressure
Transjugular intrahepatic portosystemic shunt (TIPS)
- expandable metal is palced within the liver
- bridge the portal vein to the hepatic vein
- decrompresses protal vein pressyre
- reduction in variccal pressure
- reduction in ascites
Abdominal aortic aneurysm – AAA
A permanent pathological dilation of the aorta with a diameter >1.5 times the expected anteroposterior (AP) diameter of that segment, given the patients sex and body size. The most commonly adopted threshold is 3cm or more. More than 90% of aneurysms originate below the renal arteries.
MOA of AAA
- Usually due to the degeneration of the media layer of the arterial wall
- Media- smooth muscle cells with elastin and collagen
- AAA forms due to degradation of elastin and collagen
- Media- smooth muscle cells with elastin and collagen
Lumen gradually starts to dilate
AAA Risk factors
- Male
- Inherited risk
- Increasing age
- Smoking
AAA Symptoms
- Most are asymptomatic until acute expansion or rupture
- pulsating mass or feeling is stomach
- Can cause symptoms by compressing other nearby structures
- Stomach (nausea)
- Bladder (urinary frequency)
- Vertebra (back pain)
Symptoms of a ruptures AAA
- Abdominal pain
- Back pain
- shortness of breath
- Pulsatile abdominal mass- surgical referral
- Transient hypotension–> syncope
- Sudden cardiovascular collapse – 65% of ruptures AAA die before hospital
why transient hypotension (esp in early AAA rupture)
- Retroperitoneum can temporarily tamponade the bleeding
- syncope
diagnosis of AAA
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Physical exam
- Presence of pulsatile abdominal mass (less than 50%)
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Ultrasonography
- Non invasive and in the right hands very sensitive and specific
- Can also detect free peritoneal blood
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Computed tomography (CT)
- Can detect a lot of surrounding anatomy that may be relevant
- Planning for elective surgery
- Can detect a lot of surrounding anatomy that may be relevant
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Plain x-rays
- If aneurysm has calcified then can be seen on plain X-ray
non surgical treatment of AAA
smoking cessation
hypertension control
- Surveillance of AAA
- Less than 5.5 cm (most grow slowly enough to not need treatment)
- More than 5.5cm- refer to surgeons
surgery to repair AAA (2 ways)
- endovascular repair
- open surgical repair
- endovascular repair
Insert wire through femoral artery and over that wire you pass an endograft- this will expand and hook into place- seal below renal arteries and above common iliacs
- open surgical repair
- Clamp aorta
- Open the aneurysm (remove thrombus and debris)
- Suture in a synthetic graft to replace diseased segment
types of AAA
90% of AAA’s are infrarenal
