21.1 EVAR Flashcards
A 79-year-old patient presents with a leaking abdominal aortic aneurysm.
The vascular surgery/radiology
team decide to undertake an endovascular aneurysm repair (EVAR) procedure.
a) What are the main preoperative anaesthetic considerations for this procedure? (55%)
Patient assessment:
> > Rapid patient assessment.
Limited time for investigations
due to urgency of surgery.
> > Airway and past anaesthetic assessment as standard.
> > Respiratory assessment:
patients with aortic aneurysms
are commonly
smokers or ex-smokers.
Lung disease may impact on best choices for
anaesthesia.
Assess symptoms
(cough, shortness of breath, exercise
tolerance)
and signs (saturations, auscultation).
> > Cardiovascular assessment:
patient likely to have longstanding
hypertension and possibly coronary artery disease.
Take history of past issues and
check for current symptomatology.
Also assess cardiovascular stability
from the point of view of leaking aneurysm,
which will impact on choices for anaesthesia.
> > Ask about history of diabetes mellitus and chronic kidney disease.
Diabetes should be controlled
intraoperatively with variable rate insulin
infusion.
Chronic kidney disease is associated with long-standing hypertension,
so there is increased likelihood in these patients.
EVAR involves significant contrast dose ***
risking deterioration in function.
> > Assess preoperative functioning.
This information is relevant when
considering postoperative management
in the intensive care unit.
> > If patient was known to have an aneurysm,
they may already have undergone preoperative assessment and investigation,
which can help guide the current situation.
> > Medications and allergies.
> > Time of last meal.
> > Blood tests: two samples for cross-match,
full blood count, coagulation,
arterial blood gas,
make use of near-patient testing
for speed of results.
Patient management:
» A/B: Oxygen 15 l/min non-rebreathe bag.
> > C: Two large-bore cannulae to be sited
but fluid administration is to
be restricted to that necessary
to maintain cerebration.
Raising blood pressure could change
the leaking aneurysm into a ruptured aneurysm.
> > D: small increments of morphine
titrated against pain. However, do not
give if patient is obtunded or
blood pressure is critically low.
Organisation, communication, staffing:
> > Contact consultant on call and
other members of on-call team for assistance.
> > Contact theatres:
possibility of converting to open procedure,
need for staffing.
> > Discuss with ODP:
check their familiarity with radiology suite.
Ensure anaesthetic machine, drugs,
difficult airway trolley are in location and
ready for use.
> > Liaise with radiology suite:
radiographer to ensure preparations are being
made to receive the patient.
> > Contact blood bank to request blood products
– institute major haemorrhage protocol if necessary.
> > Discuss with vascular surgical colleagues – establish surgical plan.
> > Ensure porters available for blood product access and to help transfer to radiology.
> > Discuss with intensive care consultant
regarding postoperative care.
> > Explain plans and prognosis with the patient and the patient’s family.
b) Describe options for providing anaesthesia for this case and give the advantages/disadvantages of
each. (45%)
Whatever the choice of anaesthesia, all patients will need:
» Full monitoring.
> > IABP
(right radial for ease of access
once c-arm is in place and in
case of need for surgical access
via the left radial artery).
> > Consideration of central line
(depends on comorbidities, cardiovascular
stability, time permitting –
difficult to get access after
procedure starts due to c-arm).
> > Avoidance of nephrotoxins.
> > Large volumes of fluid to avoid
contrast-induced nephropathy (CIN) (aim
to limit amount of contrast used if possible).
> > Urinary catheter.
> > Heparin 5000u on exposure of arteries
(depends on degree of leak – this
would be omitted if patient was coagulopathic).
> > Availability of emergency drugs.
Options
Local anaesthesia +/− sedation
Neuraxial block +/− sedation
General anaesthesia
Local anaesthesia +/− sedation
Local anaesthesia +/− sedation
Advantages
Preservation of cardiovascular stability.
Avoids affecting respiratory mechanics in
patients with respiratory comorbidity.
Good postoperative pain control.
If patient fully awake, they can cooperate with
periods of cessation of breathing.
Disadvantages
Need to lie still for a long period.
Does not deal with ischaemic pain caused by
periods of arterial occlusion.
Respiratory or cardiac comorbidities may
make lying flat problematic.
Does not facilitate conversion to open
procedure.
Sedation may cause dysphoria.
Neuraxial block +/− sedation
Neuraxial block +/− sedation
Reduced pain from ischaemia
compared to local anaesthesia.
Good postoperative analgesia.
If patient fully awake, they can cooperate with
periods of cessation of breathing.
Disadvantages
Restlessness due to prolonged immobility on a
narrow table remains a problem.
Risk of neuraxial procedure in a patient who
may already have deranged coagulation from
blood loss.
Patient will be anticoagulated
postoperatively, so need careful timing of
removal of epidural catheter
Spinal may not offer sufficient duration of
anaesthesia and is associated with more
cardiovascular side effects than epidural
Does not facilitate conversion to open
procedure.
Sedation may cause dysphoria.
General anaesthesia
General anaesthesia
Advantages
Permits conversion to open procedure.
Maximally comfortable for patient
intraoperatively.
Can control breathing of intubated, ventilated
patient.
Secured airway – in all other situations,
patient at risk of aspiration if becomes
obtunded.
Disadvantages
Potential for cardiovascular instability in
already compromised patient.
Does not offer any inherent postoperative
analgesia (although little is required for EVAR).
Key points
Mortality from rAAA remains high, at approximately 80%.
Protocols for the assessment and transfer of patients with rAAA improve outcomes.
Emergency endovascular repair is becoming more common.
Survival outcomes are comparable to those from open repair.
Challenges of anaesthesia for ruptured endovascular
aneurysm repair (REVAR) involve managing an unstable patient in a hybrid theatre.
Local anaesthesia for REVAR is associated with a better 30-day mortality than GA.
An abdominal aortic aneurysm (AAA) is defined
An abdominal aortic aneurysm (AAA) is defined as a
widening of the aortic lumen to >1.5 times its normal
diameter or to greater than 30 mm in absolute diameter
Decision
rapid review of the patient’s health
and functional status should be undertaken, including
assessment of common comorbidities such as ischaemic
heart disease, cardiac failure, renal disease, respiratory disease
and history of smoking. Medications must be reviewed. It
is particularly important to ascertain whether the patient is
taking anticoagulant drugs, which will potentiate ongoing
haemorrhage, and advice should be sought from a haematologist
in this instance. Metabolic equivalents of task (MET)
and Frailty Index scoring can be used to quantify premorbid
functional status, but there is no strong evidence that any
individual patient characteristics or scoring systems are useful
in deciding whether a patient will survive surgery for
rAAA.9
Resus
IMPROVE trial found a linear correlation
between 30-day mortality and the lowest recorded systolic
arterial pressure, with average mortality rates of 51% when
the recorded systolic pressure was <70 mmHg
90 and 120 mmHg with an emphasis on assessment of
GCS
The use of relative volume restriction should not be
confused with a lack of need for wide-bore i.v. access, which
must be inserted at the earliest opportunity.
