Vascular
A 72 year old man presents to the Emergency Department with left loin pain radiating to the groin. He gives a 2 day history of the pain gradually worsening and has had a single episode of syncope today. Urinalysis shows microscopic haematuria. He has a past medical history of hypertension and heavy smoking. On examination you note cool peripheries and a tender central abdomen. His observations are recorded as:
- Heart rate: 110 beats per minute
- Blood pressure: 103/78 mmHg
- Respiratory rate: 28 breaths per minute
- Oxygen saturations: 91% on air
- Temperature: 37.6°C
What is the diagnosis?
Answer:
Abdominal aortic aneurysm (AAA) is a disease that typically affects men with a history of hypertension and smoking. Whilst a number of risk factors have been suggested, over 90% of AAAs are thought to be the result of a degenerative process that commences due to atherosclerosis, affecting the medium and large blood vessels. Other causes include infections (mycotic aneurysms) and connective tissue disorders (Marfan’s disease). Most patients will be asymptomatic but patients with rupture can present with a range of symptoms such as back pain, loin pain, groin pain or even collapse. This patient is hypotensive and tachycardic and has pain that is progressively getting worse. These symptoms should always raise suspicion for AAA.Abdominal Aortic Aneurysm
Vascular
Last Updated: 1st August 2022
Abdominal aortic aneurysm (AAA) is a permanent pathological dilation of the aorta with a diameter >1.5 times the expected anteroposterior (AP) diameter of that segment, given the patient's sex and body size. The most commonly adopted threshold is a diameter of 3 cm or more. More than 90% of aneurysms originate below the renal arteries.
Patients are usually asymptomatic and their abdominal aortic aneurysm is detected incidentally. For AAA detected as an incidental finding, surveillance is preferred to repair until the theoretical risk of rupture exceeds the estimated risk of operative mortality. Repair is indicated in patients with large asymptomatic AAA.
Identifying symptomatic or ruptured abdominal aortic aneurysms
Rupture of abdominal aortic aneurysm causes a large number of deaths, many of which occur suddenly out of hospital. Even when the patient reaches hospital alive, there is significant mortality. The best chance of survival lies with early diagnosis, prompt resuscitation, and rapid transfer to theatre.
Think about the possibility of ruptured AAA in people with new abdominal and/or back pain, cardiovascular collapse, or loss of consciousness.
Be aware that ruptured AAA is more likely if they also have any of the following risk factors:
- An existing diagnosis of AAA
- Age over 60
- They smoke or used to smoke
- History of hypertension
- Female sex (although AAAs are 4 - 6 times more prevalent in men than women, risk of rupture is greater in women than in men)
The abdomen can be palpated for a pulsatile abdominal mass and abdominal tenderness. Aneurysm palpation on clinical examination has only been shown to be sensitive in thin patients and those with AAA >5 cm, with an overall sensitivity and specificity of 68% and 75%, respectively.
Imaging technique
- Offer an immediate bedside aortic ultrasound to people in whom a diagnosis of symptomatic and/or ruptured AAA is being considered. Discuss immediately with a regional vascular service if:
- The ultrasound shows an AAA or
- The ultrasound is not immediately available or it is non-diagnostic, and an AAA is still
suspected.
- Consider further imaging with thin-slice contrast-enhanced arterial-phase CT angiography for people with a suspected ruptured AAA who are being evaluated for AAA repair.
Initial management
- Airway management (supplemental oxygen or endotracheal intubation and assisted ventilation if the patient is unconscious).
- Obtain venous access with two large- bore venous cannulae.
- Send blood for FBC, U&E, glucose, baseline coagulation screen, LFTs, and emergency cross- matching, as per the hospital’s massive transfusion protocol.
- Give IV analgesia (e.g. morphine titrated according to response).
- Provide IV antiemetic (e.g. cyclizine 50mg).
- Avoid excessive IV fluid resuscitation. Treat major hypovolaemia, but accept moderate degrees of hypotension (systolic BP >90 mmHg). In general, patients who are conscious and passing urine require minimal IV fluid therapy until theatre.
- Ensure blood product (packed red cells, platelets, and fresh frozen plasma) availability and transfusion for resuscitation, severe anaemia, and coagulopathy.
- Obtain a CXR.
- Insert a urinary catheter and a radial arterial line, and record an ECG.
- Call the vascular team early to consider open or endovascular aneurysm repair (EVAR).
- Ensure that other relevant staff (e.g. ICU, emergency theatre staff ) are informed.
Emergency transfer to regional vascular services
- Be aware that there is no evidence that any single symptom, sign or prognostic risk assessment tool can be used to determine whether people with a suspected or confirmed ruptured abdominal aortic aneurysm (AAA) should be transferred to a regional vascular service.
- When making transfer decisions, be aware that people with a confirmed ruptured AAA who have a cardiac arrest and/or have a persistent loss of consciousness have a negligible chance of surviving AAA repair.
- For guidance on care of people with a ruptured AAA for whom repair is considered inappropriate, see the NICE guideline on care of dying adults in the last days of life.
- When people with a suspected ruptured or symptomatic unruptured AAA have been accepted by a regional vascular service for emergency assessment, ensure that they leave the referring unit within 30 minutes of the decision to transfer.
- Emergency departments, ambulance services and regional vascular services should collaborate to:
- Provide a protocol for the safe and rapid transfer of people with a suspected ruptured
or symptomatic unruptured AAA who need emergency assessment at a regional
vascular service. - Train clinical staff involved in the care of people with a suspected ruptured or
symptomatic unruptured AAA in the transfer protocol. - Review the transfer protocol at least every 3 years.
- Provide a protocol for the safe and rapid transfer of people with a suspected ruptured
Complications
Complications after treatment include:
- Abdominal compartment syndrome
- Ileus, intestinal obstruction and ischaemic colitis
- Acute kidney injury
- Post-implantation syndrome
- Amputation due to limb ischaemia
- Spinal cord ischaemia
- Impaired sexual function
- Anastomotic pseudoaneurysm
- Aortic neck dilation
- Graft infection
- Ureteric obstruction
- Functional gastric outlet obstruction
- Graft limb occlusion
- Distal embolisation
- Endoleak
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
