Abdominal Aortic Aneurysm

Abdominal Aortic Aneurysm

Feb 27, 2018 1
emergency,onthepods,vascular surgery

James talks to Dr Shannon Thomas about the approach to the Abdomnial Aortic Aneurysm.

Summary Writer:  Rose McCarthy

Script Writer:  Nedal Katib

Editor:  Shannon Thomas

Interviewee:  Shannon Thomas

About Dr Shannon Thomas

Dr Shannon Thomas is an Australian trained Vascular, Endovascular and Renal Transplant Surgeon who holds appointments at the Prince of Wales Hospital in Sydney, and a conjoint lecturer position at the University of New South Wales. Having completed post-fellowship training at the Park Krankenhaus Hospital in Leipzig, Germany and Polyclinico Abano Terme in Veneto, Italy, Shannon has developed a subspecialty interest in Diabetic Vasculopathy. In particular, small vessel angioplasty techniques to salvage critically ischaemic limbs. His other interests include interventional nephrology (Renal Access), Aortic Aneurysmal and occlusive disease, as well as Spinal Access surgery. These interests are accompanied by active vascular research and teaching commitments.

Abdominal aortic aneurysm

With Dr Shannon Thomas, Vascular Surgeon, Prince of Wales Hospital, Sydney, Australia

Introduction

A ruptured abdominal aortic aneurysm (AAA) is a vascular emergency. Always consider AAA in any patient complaining of abdominal/back pain and presenting with hypotension. Classically the hypotension will be refractory, as the ruptured aneurysm can tamponade itself so the blood pressure (BP) may stabilise before re-bleeding again. Maintaining permissive hypotension in these patients is crucial as is involving the vascular surgeons early.

Case 1

You are a junior doctor in the Emergency Department. You are to see an elderly patient with acute abdominal pain and low blood pressure.

  • The patient has lost consciousness
  • The paramedics have had difficulty controlling the low blood pressure
  • The patient has a history of a AAA
  • History
    • Patient complaining of intense abdominal and/or back pain
      • However, the pain may also be non-specific – e.g. loin-to-groin pain, testicular pain or pain referred to the chest or legs
    • Acute onset of pain – for ruptured AAA
    • Subtle pain over weeks – for symptomatic non-ruptured aneurysm
    • Syncope
    • Shortness of breath
    • Leg/abdominal swelling
    • Blood in urine
    • Vomiting – due to the aneurysm blocking the duodenum
    • Per-rectal bright red bleeding – fistula between abdomen and the bowel
    • Risk factors: heavy smoking, family history of AAA (especially if a first-degree female relative), history of repaired AAA, history of an aneurysm elsewhere
  • Examination
    • Hypotension – intermittent, refractory
    • Tachycardia –may not be present if the patient is on rate-control medication (e.g. beta-blocker)
    • Abdominal exam – abdominal tenderness (central and epigastric), bruising on flanks (suggests leak from AAA), palpating a AAA
  • On history –the fact that the patient has abdominal pain has been missed
  • On exam – it has not been appreciated that the blood pressure has been a problem; the patient has required a lot of fluid to maintain blood pressure
  • Renal colic attributed to the cause of the pain with no CT scan to confirm diagnosis
  • Gastroenteritis attributed to the pain
  • Most AAA are located in the infra-renal portion of the abdominal aorta
  • About 5-10% of people over 65 years will have some form of ectasia of the abdominal aorta
    • 2-5% will have an aneurysm of the abdominal aorta
  • An aneurysm <5cm has a less than 1% chance of rupture per year
  • An aneurysm >5cm is concerning
  • An aneurysm >5.5cm is indication for surgical repair
  • Aneurysm: All layers of the vessel are expanded
  • Dissection: Intima and media layers of the vesselwall come away from the adventia
    • Blood then tracks into this space to separate the wall layers
  • When the diagnosis is in doubt, a bedside ultrasound is a good test by a trained physician
  • If an AAA is found, then call the vascular team immediately
    • If the patient is stable, then a CT scan would be indicated
    • If they are perishing with hypotension (requiring IVF/blood products), then the patientis indicated to go straight to the operating theatre
  • The preferred approach is a CT scan to determine the anatomy and size of the aneurysm prior to theatre to plan an endograft to place into the aorta
    • CT scan may reveal difficult anatomy which can lead straight to an open AAA repair instead
  • If you have a patient with hypotension and your pre-scan suspicion is high for AAA, the patient will die without repair and treatment of that aneurysm
  • Do the CT scan with contrast and managerenalissues afterwards
  • If there are alternative diagnoses that would easily explain the patients’ symptoms and signs, then you can do a non-contrast CT scan
    • This will still show a retroperitoneal haematoma, or breaks in the calcification in the aneurysm,even if there is an aneurysm there or not
  • Permissive hypotension involves avoiding fluid resuscitation for the patient until a normal blood pressure is reached
  • The blood pressure needs to be just enough so that the patient is conscious (i.e. perfusion of their brain)
  • For example, a patient with systolic BP 80mmHg who is talking does not require a bolus of fluids
  • Only bolus a patient with fluids until they are conscious
  • Never aim to have systolic BP>120mmHg
  • Patients being aggressively resuscitated to bring blood pressure to normal do worse in terms of AAA outcomes
    • It is hypothesised that the rising blood pressure break the tamponade on the ruptured AAA and cause more bleeding and deterioration
  • ICU
  • Anaesthetics
  • Blood bank – massive transfusion protocol activation
  • Do nothing and palliate the patient – many patients are elderly and come from nursing homes, attempting to repair the aneurysm can usually be futile considering their comorbidities
  • Stent graft repair – the graft is placed percutaneously through the femoral artery; blood is then redirected completely through the endograft
  • Open repair – a trouser graft is sewn into the aorta and common iliac arteries
  • Post-op recovery in ICU for resuscitation
  • If you see someone on the ward who has abdominal pain with a low blood pressure, think AAA
  • If you don’t consider it, it is a diagnosis that can be missed with fatal consequences

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Tags: #AAA,#abdominal exam,#abdominal pain,#Abdomnial Aortic Aneurysm,#aneurysm,#emergency department,#hypotension,#low blood pressure,#shortness of breath,#surgery,#tachycardia,#vascular emergency,#vascular surgery

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1 Comment

  1. Thomas Thomas Chowattukunnel Jr

    March 1, 2018 at 6:56 am

    Excellent Podcast of AAA

    Reply

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