Anaesthesia for interventional neuroradiology

1. Anaesthesia for
Interventional
Neuroradiology
Presentor : Dr.Kumar
Moderator : Dr.chaitanya

2. Intro
 A trend towards minimally invasive neurosurgery, an important development in
which has been the introduction of the Guglielmi detachable coil (GDC) for
endovascular aneurysm coiling.
 Anaesthesia is required for neuroradiological diagnostic procedures such as
angiograms,computerized tomography (CT), and magnetic resonance imaging
(MRI) or for therapeutic intervention

3. Indications

4. Anaesthetic concerns
 INR procedures, including
1. maintaining immobility during procedures to facilitate imaging
2. rapid recovery from anesthesia at the end of procedures to facilitate
neurologic examination and monitoring or to provide for intermittent
evaluation of neurologic function during procedures
3. managing anticoagulation
4. treating and managing sudden, unexpected procedure-specific
complications during procedures (eg, hemorrhage or vascular occlusion)
which may involve manipulating systemic or regional blood Pressures
5. guiding the medical management of critical care patients

5. Pre operative assessment
 Patients who have had an SAH can have marked
derangement of various organ systems
 Pulmonary complications are the most common non-
neurological cause of death

6. Neurology
 A brief history and short neurological examination should
be carried
1. Glasgow Coma Scale,
2. Grade of SAH
3. Any cranial nerve, visual field, and
4. Motor and sensory deficits
 The nature, location, and size of the lesion and previous
treatment must also be ascertained.

7. Cardiovascular system
 Massive catecholamine release is the most likely cause of cardiac
dysfunction seen after SAH.
 This may include dysrhythmias, abnormal ECG morphology (T
inversion, ST depression, Q waves, U waves, and prolonged QT),
elevated cardiac enzymes, and frequent left ventricular dysfunction
and pulmonary oedema.
 Therapy with oral anticoagulants should be stopped and, if
necessary, converted to heparin, which can be stopped or reversed,
if required.

8. Respiratory system
 In addition to the strong causal relationship between
SAH
 cigarette smoking
 reduced levels of consciousness
 prolonged bed rest
predispose to atelectasis and pneumonia

9. Metabolic considerations
 Tight control of blood glucose is essential since hyper- and
hypoglycemia are associated with poor outcomes,particularly in the
presence of cerebral ischaemia.
 Patients are often dehydrated with electrolyte disturbances such as
1. hypomagnesaemia,
2. hypernatraemia,
3. hyponatraemia associated with the syndrome of inappropriate ADH
secretion,
4. hypokalaemia, and
5. hypocalcaemia

10. Conduct of anaesthesia
 Premedication
 Premedication should be individualized. A titrated dose of a
benzodiazepine (e.g. midazolam) provides anxiolysis, sedation of short
duration, and amnesia, although it can impair assessment of neurological
status and worsen confusion
 Narcotics are best avoided because of potential respiratory depression and
hypercarbia.
 H2 -receptor antagonists, alone or with metoclopramide, may be used to
reduce the risks of gastric aspiration.
 Nimodipine is frequently used to reduce cerebral ischaemia consequent to
cerebral vasospasm.

11. Induction
 The overriding priority is to maintain cardiovascular
stability, avoiding surges in arterial pressure that might
cause aneurysm rupture while maintaining adequate
perfusion of a possibly ischaemic cerebral circulation.
 To this end, propofol is usually used to induce
anaesthesia combined with remifentanil, alfentanil, or
fentanyl; thiopentone and etomidate are alternatives.
 Pressor responses can also be obtunded with i.v.
lidocaine or rapid, short-acting b-blockers (e.g. esmolol).

12.  Before tracheal intubation, it is important to ensure that
neuromuscular block is profound; before administration of
neuromuscular blocking agent, the correct placement of
electrodes for peripheral nerve stimulation should be verified.
 Rocuronium, atracurium, or vecuronium are suitable for
neuromuscular block. It is useful to use a cut endotracheal
tube so that the image intensifier does not push in or kink the
tube
 The laryngeal mask airway has also been used in this setting;
there is insufficient evidence to recommend its routine use

13. Maintainence
 Sevoflurane is the volatile anaesthetic agent of choice
because of its low potential for increasing CBF – ICP and its
rapid offset.
 Up to 1 MAC, there is preservation of the reactivity of cerebral
blood vessels to carbon dioxide and coupling of CBF and
CMRO2
 Sevoflurane also provides faster recovery and postoperative
neurological assessment than isoflurane.
 Nitrous oxide (N2O) elevates CBF and ICP and increases the
consequences of air embolism; it should not be used

14.  The use of a TIVA technique incorporating propofol and a short-
acting opioid reduces CBF, ICP, and CMRO2.
 Of the short-acting opioids, remifentanil is frequently used; it provides
stable haemodynamics and allows more rapid recovery from
anaesthesia than alfentanil or fentanyl
 Rebound hypertension may develop on sudden discontinuation of
the infusion, necessitating a slow decrease in rate before
emergence.
 Propofol and remifentanil, sevoflurane and remifentanil, and a
combination of propofol and remifentanil supplemented with
sevoflurane.

15. Ventilation
 Ventilation aims for mild hypocapnia to normocapnia (Paco2 4 – 4.5 kPa) to
help control ICP
 It is important to distinguish two general settings where hyperventilation is
used in anesthetic practice.
 First, it is used to treat intracranial hypertension.
 Hyperventilation is an important mainstay of the acute management of an
intracranial catastrophe to reduce cerebral blood volume acutely.
 The second, far more common, application is to provide brain relaxation after
the skull is open with the intent of providing better surgical access and,
presumably, a lesser degree of brain retraction for a given surgical approach

16. Delibrate hypertension
 During acute arterial occlusion or vasospasm, the only practical
way to increase collateral blood flow may be an augmentation
of the collateral perfusion pressure by raising the systemic
blood pressure.
 The extent to which the blood pressure has to be raised
depends on the condition of patients and the nature of the
disease.
 Typically, during deliberate hypertension, the systemic blood
pressure is raised by 30% to 40% above the baseline in the
absence of some direct outcome measure, such as resolution
of ischemic symptoms or imaging evidence of improved

17.  Phenylephrine usually is the first-line agent for deliberate
hypertension and is titrated to achieve the desired level of blood
pressure.
 The EKG and ST segment monitor should be inspected carefully for
signs of myocardial ischemia.
 The risk for causing hemorrhage into an ischemic area must be
weighed against the benefits of improving perfusion, but
augmentation of blood pressure in the face of acute cerebral ischemia
probably is protective in most settings.
 There also is a risk for rupturing an aneurysm or arteriovenous
malformation (AVM) with induction of hypertension

18. Delibrate hypotension
 The two primary indications for induced hypotension are
1. to test cerebrovascular reserve in patients undergoing
carotid occlusion.
2. to slow flow in a feeding artery of brain AVMs before
glue injection (sometimes termed ‘‘flow arrest’’).
 The most important factor in choosing a hypotensive
agent is the ability to achieve safely and expeditiously the
de-sired reduction in blood pressure while maintaining
patients physiologically stable

19. Anti coagulation
 Heparin is administered as an initial i.v. bolus (5000
IU) or 70 units /kg followed by intermittent boluses or
an infusion to keep ACT 2 – 3 times baseline; ACT is
monitored hourly.
 For reversal of heparin anticoagulation, protamine is
used in a dose of 1 mg per 100 units of heparin or
dosed according to the heparin dose – response
curve.
 Complications of protamine administration include
I. hypotension,
II. anaphylaxis,
III. pulmonary hypertension

20.  Direct thrombin inhibitors inhibit free and clot-bound
thrombin, and their effect can be monitored by either
activated partial thromboplastin time or ACT.
 Lepirudin and bivalirudin, a synthetic derivative, have
half-lives of 40 to 120 minutes and approximately 25
minutes, respectively.
 Because these drugs undergo renal elimination, dose
adjustments may be needed in patients who have renal
dysfunction.

21. Temperature
 Control of body temperature is important;
 hyperthermia is associated with poor outcome, and
 mild hypother-mia has not shown to improve
neurological outcome

22. Recovery
 A rapid and smooth recovery is desirable to facilitate
early neurological assessment and safe transfer to
recovery areas.
 Blood pressure is allowed to return to normal or up
to a systolic pressure of 160 mm Hg.
 An unsecured or incompletely secured aneurysm
may call for induced hypotension.
 Patients who have had neurological complications
may need to be transferred to neurointensive care
for continued sedation and ventilation

23. Complications
 Vascular complications are either haemorrhagic or
occlusive
 Vascular rupture or perforation may be:
1. spontaneous;
2. due to hypertension during laryngoscopy,
emergence, inadequate depth of anaesthesia, or
associated with the use of vasoactive drugs.
3. brought about by the microcatheter, guide wire,
coil, or injection of contrast

24. Management of intracranial catastrophes

25. Specific procedures

26. Tumors & AV malformations
• Maintain lower blood pressure
a. Reduces flow through fistulous lesion
b. Greater precision for delivery of cyanoacrylate
glues
c. To prevent glue passage into the draining veins or
systemic venous system

27. Intracranial Aneurysms
• 2 basic approaches
1. occlusion of proximal parent arteries
2. obliteration of the aneurysmal sac. (coil
embolization )
Risks – spontaneous rupture, leaky sac, vascular
rupture secondary to manipulation
Alternate – stent assisted coiling methods
• Risks - parent vessel occlusion, thromboembolism,
or vascular rupture.

28. AV malformations
• Goal : To obliterate as many of the fistulae and their
respective feeding arteries as possible
• Method : embolization with cyanoacrylate glues
• Complications :
1. Acute hemorrhage
2. Pulmonary embolism

29. Carotid Angioplasty & Stenting
 Anesthetist services are mostly requested
for compromised patients
 Relative contraindications to CAS include –
• Antiplatelet agent intolerance,
• Other pending surgery that precludes antiplatelet agents,
• Aortic arch disease (age)
• Altered carotid morphology, including carotid tortuosity,
concentric calcification (which entails a risk of vessel
rupture),
• Heavy thrombus burden, and unstable plaque

30. THANK YOU