Anaesthesia for intracranial vascular surgery - PowerPoint Presentation

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Anaesthesia for intracranial vascular surgery

Dr. S. Parthasarathy

MD., DA., DNB, MD (

Acu

),

Dip.

Diab.DCA

, Dip. Software

statistics,Phd

(

physio

)

Mahatma Gandhi Medical college and research institute ,

puducherry

, India

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What is it ?? A localized dilation or ballooning of blood vessels

Dr

SPS

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Incidence and sites

Incidence : 1 to 6%

•Incidence of ruptured aneurysm: 12/100,000

•Age: any age, peaks 40 - 60.

•Sex: M/F 2:3 Sites : 30% ICA

40% ACA( Anterior Communicating) 20% MCA

10%

Vertebro

-basilar systems

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Anterior – 85 %

85 %

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Types

Berry (

pedunculated

)

Fusiform

Dissecting

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Mostly asymptomatic

•Subarachnoid hemorrhage (SAH) due to

aneurysmal

rupture

–Lethal event: 25% don’t even get to the hospital

–In hospital mortality rate up to 50%

–Most survivors have permanent disability

Size – < 12 mm , 12 to 24 mm, > 24 mm

Neuronal injury due to bleed

Vasospasm

Rebleeds

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The three main predictors of mortality and dependence impaired level of consciousness on admission,

advanced age,

and large volume of blood on initial cranial computed tomography

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Clinical features

Incidental finding if un ruptured

Hematoma and edema

Ruptured: sudden severe headache “worse headache of my life”, nausea, vision impairment, vomiting, & LOC

Hydrocephalus- blood clots on Subarachnoid granulations & ventricles ↓ CSF absorption & obstruct CSF drainage

Increased ICP , stroke Lethal event: 25% don’t even get to the hospital

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Hunt and hess scale

2

Mortality

35 %

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Fischer - CT scan based features

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World federation of neuro surgeons

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Vasospasm- 13.5% cause of mortality & morbidity.

Most feared complication of SAH

•Occurs 1 to 2 weeks following initial hemorrhage

Patho

physiology not well understood

Blood in SAS→ inflammation → entrapped macrophages and neutrophils →

endothelins

& free radicals → vasospasm → stroke

New onset

neuro

signs

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Vasospasm

Magnetic resonance angiography (MRA)

Ct angiography

Transcranial

doppler

ultrasonography (TCDs) Intra-arterial digital subtraction angiography GOLD STANDARD but invasive

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Nimodipine

Improve outcome in vasospasm

Oral 60mg 4Hly, max dose 360mg for 21 days

IV 1mg/hr during the first 6 hrs,

increase gradually to max 2mg/hr

Maintain SBP 130-150mmhgrisk of hypotensioncentral line to avoid

thrombophlebitis

.

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Hypertension,

hypervolumia

,

hemodilution

( 3 H )

SBP 120-150 mmhg

in unclipped

160-200 mmHg in clipped aneurysm.

CVP 8-12mmHg

HCT 30-35%

Intraarterial

papaverine

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Rebleeds

The overall incidence of re bleeding is 11%.

1 – 12 days

Deterioration

70 % mortality

Prevention

BP maintain , seizure control ,ICP maintenance

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What should we do ??

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From outside

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Or from inside

Thrombogenic

– new

intima

will grow inside

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When to touch 0- 3 days

4 – 10 days

Controversial

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Preoperative evaluation

Careful medical history

Physical examination

Baseline BP , fluid status

Hyponatremia (brain

natriuretic peptide) Prolonged bed rest runs the risk of

atelectasis

and pneumonia .

CNS examination

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Pre op work up

Investigations --- for the diagnosis

Routine + ECG, ECHO,

CxR

, coagulation profile T wave inversion & ST depression (most common), Prolong QT (atrial

& ventricular dysrhythmias) -- catecholamine surge

Pregnancy test ( pregnant ruptures the

aneurysm

)

Talk to the surgeon also

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Neuro radiology

Cerebral Angiogram

Site of the aneurysm

Prepare for

intraop

positioning, surgical exposure &

monitoring

CT scan

Amount of subarachnoid blood in the basal cisterns

is good predictor of delayed vasospasm

Increase ICP from IC

haemorrhage

, hydrocephalus

or cerebral

oedema

TCD

facilitate vasospasm management

.

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Premedication

Calcium channel-blocking drugs, anticonvulsants, and steroids are continued.

No sedatives

No narcotics

Possible acid aspiration prophylaxis

preoperative administration of erythropoietin in elective cases might reduce injury from reversible ischemia during temporary clipping

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Cardiac evaluation

Elevated

Troponin

17-28%

Elevated CKMB 37%

Echo LV dysfunction Syndrome of neurogenic

-stunned myocardium

Cardiogenic

shock

pulmonary

oedema

But OK – don’t postpone – no added treatment

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Monitoring

CVS : ECG, Arterial line (IBP), CVP (

cubital

fossa)

RESP : SpO2, End tidal CO2, oesophageal stethoscope

NEUROMUSCULAR : Train of 4 (by PNS) (it is essential that these patients do not move)

CNS : Either BIS/EEG or EPs

RENAL : U/O, all these patients are catheterised the U/O provides an indication that the diuretics are working

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Monitoring

brain temperature

Intermittent arterial blood gases, glucose, electrolytes,

osmolality

, hematocrit

, urine output EEG evoked potentials – duration of occlusion? IV

anaesthetics

better

Jugular bulb oxygen monitoring can also be helpful in patients at risk for global cerebral ischemia.

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Can we place the leads ??

SSEP monitoring has mostly been used during aneurysm surgery in the territory of both anterior and posterior cerebral circulation,

BAEP monitoring has been used during operations in the territory of the vertebral-basilar circulation

.

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Anesthetic Management

Goals

Decrease

transmural

pressure gradient

Don’t try to control ICP much !!

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Goals maintaining adequate CPP and cerebral oxygenation;

preventing the development of a “tight” brain from cerebral edema or vascular engorgement

.

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Induction !!!

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Induction

Thio

– 5- 6 mg/Kg

Smooth induction – narcotics

IV lignocaine or

esmolol Scoline – OK

Vecuronium

– complete muscle relaxation

Local and

fentanyl

for pinning

Normotension

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Maintenance

Nitrous ?? ,

fentanyl

,

propofol - infusion BP should be kept within previously defined limits according to the patient’s baseline BP. Target is usually 20 mm Hg below baseline

Prior Beta blockade may help

Mannitol

(1.5 gm/kg) combined with

Frusemide

(0.3mg/kg) is given to shrink the brain

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Crucial times

Securing of head with Mayfield pins

Skin Incision

Periosteal

Flap elevation and Bone cutting.Narcotic,

propofol , Local

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The basics of brain slackness

crucial for safe surgical dissection to proceed.

implement moderate

hypocapnia

(PaCO2 25–30 mmHg);

elevate the head position; Add diuretics and mannitol

;

Drain spinal fluid;

Avoid cerebral vasodilators

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BP ?? !! Before clipping – get down the BP

After clipping - increase to just above baseline is acceptable – 10 minutes

Hypothermia – not acceptable – vasospasm is more common

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Intra op problems

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Coiling problems

The aneurysm may rupture with the angiographic manipulation

Secondly part of the coil could

embolise

out of the aneurysm into a more distal artery

The thrombus formation may extend out of the aneurysm and cause thrombus formation in the feeding vessels

Propofol

or

Thio

No vasodilators

Control

angiographically

Rarely done with IV sedation

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Aneurysmal rupture

11% of patients with previously ruptured aneurysm (compared with an incidence of 1.2% in previously un ruptured aneurysms).

Maintain fluid and

BP ??

Clamp before and after the aneurysm

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Reversal

The patient is not

extubated

until they are awake and breathing well

BP should be controlled with

Propofol or Narcotics infusionFurther agents to control BP (Beta blockers) during

extubation

might be used if infusions are found unsatisfactory

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Post op problems

Neuro

deficits – new

Then do

CT scan

If normal Do angio

for vasospasm

Vasospasm

Rebleeds

Infarction

Fluid status

Urine output

Hyponatremia

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Summary Worst headache (

neuro

, vasospasm,

rebleeds

) Incidence ( impending doom!!) Hunt, Fischer WFNS

Ecto and endo

Pre op – CNS, general, investigations

Induction – maintenance - recovery

Post op monitoring

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Thank you all