Page 22 - CASA Bulletin of Anesthesiologisy 2022 9(6)-1 (3)

CASA Bulletin of Anesthesiology

the P2Y12 platelet receptor inhibitor Clopidogrel. This may be due to either a genetic deficiency
in the enzyme that converts clopidogrel to its active metabolite or co morbidities such as
diabetes, renal impairment, drug interactions or tobacco use that share a common metabolic
pathway. Many neuro interventionists will use the VerifyNow P2Y12 assay to measure the
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efficacy of clopidogrel activity. It measures P2Y12 reaction units (PRU) and a value <194 is
deemed adequate platelet inhibition. Patients who are deemed inadequate responders can be
treated with the newer generation thienopyridine class drugs prasugrel and ticaglor that have the
benefit of faster onset and efficacy but the downside of increased bleeding risk, cost and twice
daily dosing for ticagrelor.

When complications occur in the NIR suite successful management is dependent on effective
communication between the proceduralist and the Anesthesiologist. Although intra-procedure
aneurysm rupture is arguably the most feared and devastating complication of an endovascular
intervention it is intra-arterial thrombus formation and the risk for ischemic complications that
happens more frequently. When the proceduralist is aware of thrombus formation they will often
ask for the blood pressure to be raised, more heparin to be given and sometimes glycoprotein IIb-
IIIa inhibitors are given either locally intra-arterially or systemically intravenously to inhibit
platelet aggregation. Patients with vasospasm after sub arachnoid may present to the NIR for
possible interventions including angioplasty and possibly intra-arterial injection of calcium
antagonists such as verapamil and nicardipine directly into the constricted arteries. This may
cause profound hypotension and should be anticipated as these patients are at particular risk of
further brain injury due to cerebral ischemia.

When an aneurysm ruptures during an endovascular intervention this will usually elicit a
’ cranial
pressure. The proceduralist should be immediately alerted and they will attempt to control the
bleeding by occluding the artery with a balloon whilst coils are packed into the aneurysm. It will
often be necessary to reverse any heparin that has been given with protamine and a platelet
infusion might be necessary if the patient has received DAPT. Whilst the initial reaction to a
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normal or slightly elevated blood pressure in the setting of a balloon artery occlusion and other
maneuvers to try and lower intracranial pressure should be considered such as hyperventilation
to lower paCO2, hyperosmotic therapy and draining CSF (if a ventriculostomy has been placed
for ruptured aneurysms prior to the procedure). It may be necessary to take the patient
emergently to the OR following the procedure for a decompressive craniectomy.

Embolization Procedures

Technological advancements in both micro catheters and wires feeding arteries to both
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Again, it is of paramount importance that the patient remains immobile so that the catheter does
not migrate on injection into normal arterial branches. The proceduralist may ask for normal or
lower blood pressure on injection to try and prevent embolization of embolic materials into
draining veins causing some degree of venous outflow obstruction or even the pulmonary
circulation which may present as post procedural hypoxemia. When an AVM is embolized
relative hypotension is often necessary for up to 24hrs as blood is shunted into a chronically
hypotensive vascular bed that requires time to restore its auto-regulatory capacity.

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