Abdominal Aortic Aneurysm Flashcards
A 67-year-old male patient is admitted to the emergency department following a collapse with severe abdominal and back pain. He has a history of hypertension, COPD and type II diabetes mellitus. An emergency CT scan shows a leaking abdominal aortic aneurysm.
What is an abdominal aortic aneurysm?
- A dilated or widened part of the aorta of more than 30 mm within the abdominal cavity.
What are the risk factors for the development of an abdominal aortic aneurysm?
- Male gender.
- Increased age (>65 years old).
- Chronic cigarette smoker.
- Comorbidities: ischaemic heart disease, peripheral arterial disease,
hypertension, hyperlipidaemia, COPD, Marfan’s syndrome,
tuberculosis and Takayasu’s disease. - Positive family history.
How can the risk of a spontaneous rupture be reduced?
- Regular surveillance screening to monitor aneurysm growth.
- Smoking cessation.
- Regular exercise and adequate nutrition/weight loss.
- Pharmacological agents: statins, aspirin, beta-blockers and ACE inhibitors may all play a part in reducing the risk of growth and
rupture. - Good control of blood pressure and blood glucose levels.
- Elective surgery if the aneurysm measures >5.5cm.
The vascular team want to take this patient to theatre urgently.
What is your initial management of this patient in the emergency department?
Assessment:
* Immediate ABCDE assessment in the emergency department focusing on their conscious level and haemodynamic stability. It might be advisable to accept a lower than normal blood pressure to minimise further bleeding. The patient’s GCS should be used as a guide: the patient should remain verbally responsive.
- Continuous bedside cardiac monitoring should be instigated. Insertion of lines should not cause any delays and can be done once the patient has been anaesthetised.
- A rapid history should be taken from the patient or their relative regarding comorbidities, current medication, allergies and previous anaesthetics. An airway assessment should also be done.
Treatment:
* Insert a minimum of two large bore intravenous cannulae ready for blood transfusion.
- Consider permissive hypotension. If required, a rapid infusion device may be used to restore enough of the circulating blood volume to maintain cerebral perfusion (assessed by GCS as above). The patient’s blood pressure itself is not a reliable guide, particularly on the background of hypertension. Crystalloids should be avoided to reduce the risk of coagulopathy.
- Administer analgesia: intravenous opioids titrated cautiously.
The vascular team want to take this patient to theatre urgently. What is your initial management of this patient in the emergency department?
Continued…
Other:
* Ensure escalation to the senior anaesthetic, surgical and critical care teams to ensure that the patient receives optimal care; he has a very high risk of morbidity and mortality.
- This patient may be suitable for endovascular repair, which should be discussed early with an interventional radiologist.
- Early discussion with emergency theatre staff is necessary to facilitate rapid and efficient transfer and surgical intervention, including preparation of emergency drugs and equipment e.g. cell salvage, warming and rapid infuser devices.
- Ensure urgent preparation of blood products; consider major haemorrhage protocol activation for easy access and monitoring.
- Facilitate patient transfer to theatre with emergency drugs and equipment.
What is the Hardman index?
- The Hardman index is a scoring system that can be used to predict the mortality of a patient with a ruptured abdominal aortic aneurysm. It takes into account 5 factors:
- Age >76 years.
- Serum creatinine >190 μmol/L.
- Haemoglobin <9 g/dL.
- Ischaemic changes visible on ECG.
- Loss of consciousness following hospital admission.
- In the revised index, the risk of mortality increases to 21% with one risk factor, 60% with two risk factors and 78% with three or more risk factors.
Note that SORT and POSSUM are commonly used to assess the risk of perioperative morbidity and mortality in these patients.
How would you anaesthetise this patient?
- This is a high-risk patient with a significant likelihood of perioperative morbidity and mortality. Ideally, at least two senior anaesthetists and ODPs should be present to ensure optimal care.
- Induction of the patient should take place in theatre with the surgeons scrubbed, the patient prepped and draped, and emergency drugs and blood products readily available. This is due to the risk of decompensation on induction of anaesthesia. Clamping the aorta is likely to be necessary for rapid haemorrhage control.
- Monitoring: full AAGBI monitoring, with equipment for a catheter and arterial line ready to be placed after cross clamping, unless the patient is deemed stable enough to tolerate the delay. Temperature, cardiac output and central venous pressure monitoring should be done perioperatively.
- Ensure a minimum of two large bore intravenous access with the rapid infusion device connected and blood immediately available for transfusion. A cell saver should be readily available for use.
How would you anaesthetise this patient?
- Carry out a rapid sequence induction with the appropriate dose of drugs depending on the patient’s haemodynamic stability. Ketamine, fentanyl and rocuronium are commonly used. Induction may lead to signifcant haemodynamic instability due to the side efects of the anaesthetic agents, positive pressure ventilation and abdominal muscle relaxation. Maintenance of anaesthesia should be done with a volatile anaesthetic agent.
- Following cross clamping of the aorta for haemorrhage control, the patient should be more stable, allowing insertion of auxillary monitoring to include invasive blood pressure, CVP, BIS and core temperature. Blood samples (in particular clotting screen/TEG) should be obtained to guide further treatment, and a normal blood pressure can be restored at this point.
- Management of coagulation should be done following a discussion with the surgeons, to balance the risk of bleeding against the possibility of a clot developing in the aortic graf.
- A nasogastric tube should be inserted due to the likelihood of a postoperative ileus.
- Te patient should be transferred to intensive care postoperatively for further monitoring and treatment. It is likely that further stabilisation will be required prior to extubation.
