21.3 Open EVAR + AKI

Question 1

A 79-year-old man with a 6-cm infra-renal abdominal aortic aneurysm is to undergo an endovascular
aneurysm repair (EVAR). He is known to have chronic obstructive pulmonary disease.

a) What are the advantages of an EVAR compared to an open repair of the aneurysm for this patient?
(8 marks)

Answer 1

1&raquo_space; Open repair may be optimal in younger patients
with few comorbidities as although
the intraoperative risks are higher,
there are fewer long-term
problems with the graft,
e.g. endoleak.

This gentleman is elderly and has
comorbidities that mean that the
risk of long-term problems is less of an
issue when compared to the intraoperative
risks to him of an open repair.

2&raquo_space; In view of the patient’s age,
he is likely to have other comorbidities,
including cardiovascular and renal disease,
increasing the need for a
minimally invasive technique with fewer
perioperative complications and
less metabolic and haemodynamic stress.

3&raquo_space; EVAR offers potential for
avoidance of intubation,
effects of positive pressure ventilation
on diseased lungs,
risk of pneumonia –
EVAR may be done under neuraxial technique
or even local anaesthetic to groins.

4&raquo_space; Avoids presence of large abdominal wound,
the pain of which can cause
difficulty achieving deep breathing
and adequate cough postoperatively,

thus increasing the risk of respiratory complications.

5&raquo_space; Reduces the possible need for
opioid analgesia postoperatively with its
respiratory depressant effect.

6&raquo_space; Infra-renal aneurysms tend
to be technically the most straightforward
AAA to be done by EVAR; thus,
operating time for an awake technique
should be tolerable.

7&raquo_space; Early ambulation (next day) facilitated,
helping to maintain muscle
strength and reducing
risks of deep vein thrombosis,
deconditioning and
pneumonia in vulnerable individual.

8&raquo_space; Reduced risk of large blood loss
and coagulopathy, important in a patient
with limited reserve to tolerate it.

Question 2

b) List the risk factors for acute kidney injury (AKI) during any EVAR procedure. (6 marks)

Answer 2

> > Advancing age.*

> > Pre-existing renal impairment.

> > Diabetes mellitus.*

> > Cardiac failure.*

> > Perioperative dehydration.

> > Nephrotoxic drugs:
ACE inhibitors,
angiotensin II receptor antagonists,
aminoglycosides,
diuretics.

> > High contrast load:
including high cumulative contrast load from
preoperative investigations,
for example CT angiography

> > Surgical complications:*
embolisation of atheromatous plaque into renal
arteries, obstruction of renal arteries by stent.

Question 3

c) Describe perioperative measures to prevent AKI following EVAR. (6 marks)

Answer 3

> > Avoid perioperative dehydration:
minimise preoperative starvation time,
cardiac output monitoring to guide fluid replacement intraoperatively (and possibly postoperatively),
start fluids pre-procedure,
ensuring full circulation at that point,
monitor urine output.
Monitor blood loss and
replace, as indicated by near patient testing.

> > Avoid perioperative hypotension:
management of fluid status as earlier,
with use of vasopressor if indicated.

> > Avoid nephrotoxic drugs perioperatively where possible.
NSAIDs not a suitable choice for pain control.

> > Limitation of contrast load,**
especially in patients with pre-existing chronic
kidney disease or risk of acute kidney injury.

Scheduling of surgery so that kidneys have a week to recover from any preoperative contrast.

Some centres use sodium bicarbonate or N-acetylcysteine, although
evidence is currently lacking.

> > Glucose control:**
maintain normal range in diabetic patients,
use variable rate insulin infusion in type I diabetes.

> > Minimise surgical complications **
with meticulous technique.