Anaesthesia for intracranial SOL, including vascular surgeries

Dr. Megha Aggarwal

University College of Medical Sciences & GTB Hospital, Delhi

Outline

Introduction to SOLClassification

Presentation

Management strategies

Neuroanaesthetic goals

Hemodynamic concerns

Conduct of anaesthesiaPre anaesthetic assessment

Monitoring

Induction, maintenance and emergence

Post-operative concerns

Classification of SOLCONGENITAL Dermoid, epidermoid, teratoma.

TRAUMATIC Subdural & extradural haematoma

INFLAMMATORY Abscess, tuberculoma, syphilitic gumma,fungal granulomas.

PARASITIC Cysticercosis, hydratid cyst, amebic abscess, Schistosoma

NEOPLASMS  Meningionas, gliomas, choroid pappilomas , metastasis

VASCULAR Aneurysms, A-V malformations

Neoplasms

1. Meningioma- 90% supratentorial

5-6th decade

benign

Highly vascular with large feeding vessels

2. Gliomas - most common 1 intracranial tumors⁰

slow growing astrocytomas to malignant glioblastomas

seizures, focal deficits, ↑ ICP as per tumour type

Common SOLs

3. Tumors of ventricular system

Choroid plexus papillomas, ependymomas,

Obstructive hydrocephalus, midbrain compression

4. Metastatic

Most common intracranial tumors

Multiple

5. Intracerebral abscess

Frontal sinus, middle ear, blood born, foreign body

Meningitis , ↑ ICP

Common SOLs (cont …)

ANATOMICAL REGION CLINICAL SIGNS

Supratentorial (forebrain) Seizures

Headache

Motor/ sensory deficits

Infratentorial (brainstem)

(RAS, CN, Cardiac & resp centres)

- CN deficit (3-12)- ocular palsy, dysphagia,

laryngeal dysfunction (chronic aspiration).

- Arrhythmias/ respiratory irregularities

Sleep abnormality

Infratentorial (cerebellum) Ataxia

Tremors

Vestibular signs

Hydrocephalus

Infratentorial (vestibular system) Head tilt

Postural deficit

Nystagmus

How do they present ?

Herniation / midline shift

HTN ,

Tachy/ brady

arrythmias,

3 & 6th CN palsy (I/L

pupil dilation + no light

reflex),

C/L hemiplegia/ paresis,

Coma ,

Resp arrest

Treatment

Goals of anaesthesia

1. Preserve both injured & uninjured cerebral territories by global maintenance of cerebral homeostasis.

2. Maintain normocarbia, normotension, normoxia, euthermia, euglycemia.

3. Avoid secondary brain insults

4. Optimizing operative conditions to facilitate resection

Depending on type (vascularity) and location (supra/

infratentorial) of tumor

Anaesthetic implications

Supratentorial

ICP management

Monitoring brain function

Massive intraoperative hemorrhage

Seizures

Air embolism (if venous sinuses

traversed)

Infratentorial

Air embolism

Care during vital

structure handling

Positioning

Higher mortality

Secondary insults

INTRACRANIAL SYSTEMICIncreased intracranial pressure Hypercapnia/hypoxemia

Epilepsy Hypo-/hypertension

Vasospasm Hypo-/hyperglycemia

Herniation: falx, tentorium, foramen magnum, craniotomy

Low cardiac output

Midline shift: tearing of cerebral vessels

Hypo-osmolality

Shivering/pyrexia

AVM/ aneurysm/ head injuries/ tumors

Disruption of cerebral autoregulation

BP fluctuation poorly tolerated

↑BP – Vasogenic edema, ↑ tumor / aneurysm size, aneurysmal rupture↓ BP – Ischemia/ infarction

WHY CONTROL BP ?

Stimuli for BP fluctuation

1. Laryngoscopy

2. Intubation

3. Positioning

4. Suction

5. Skeletal fixation of

head

Preventive measures

1. Deep plane of anesthesia

2. Additional dose of iv

anesthetic agent

3. Adequate muscle

relaxation

4. Lignocaine (1.5 mg/kg)

5. Esmolol (0.5 – 1 mg/kg)

INVESTIGATIONS

EXAMINATION

HISTORY

Preoperative assessment

Assessment & documentation

Preoperative assessment1. Level of consciousness

2. Seizures - ↑ CMRO2 , ↑ ICP

3. ↑ ICP – headache, vomiting, without nausea, blurred vision, ocular palsy (CN 6)

4. Hydration – fluid intake, NPO status, diuretics, SIADH

5. Medications – steroids, antiepileptic drugs, aspirin/ clopidogrel, diuretics, mannitol

6. CN palsies- dysphagia, laryngeal dysfunction

7. Associate systemic illness- Cardiac – HTN (hypotensive anaesthesia) Respiratory Renal – intraoperative mannitol and diuretics, SIADH, DI

HISTORY

Preoperative assessment1. Mental status, level of consciousness (GCS)

2. Hydration status

3. Systemic examination

a) CNS ↑ICP – papilloedema, cushing response (↑BP, ↓HR), sutural

diastasis, bulging fontanels.

Focal signs (CN palsies) - Dysphagia, strabismus, focal seizures, speech deficit, motor & sensory examination.

Midline shift - I/L Pupillary dilatation and absent light reflex (3rd CN)

EXAMINATION

Preoperative assessment

b) Respiratory- effect of positioning, resp. pattern, neurogenic pulm. edema

c) CVS – Cushing reflex, HTN (resets limits of cerebral autoregulation), BP (cerebral perfusion)

d) GI -↑ Aspiration (steroids, ↑ ICP , low GCS, emergency)

e) Renal - ↓fluid intake, diuretics, mannitol, SIADH, DI

f) Paraneoplastic syndromes

EXAMINATION

Preoperative assessment

1. Complete blood count – Hb, TLC, Platelet count

2. RBS – hyperglycemia – cerebral edema , ↑ischemic brain injury

3. KFT – urea, Na, K

4. Coagulation profile

5. ECG – ischemic changes, arrhythmias

6. CXR

INVESTIGATION

7. CT/ MRI – tumor assessment

Location – silent/ eloquent area

Size – degree of compromise of intracranial dynamics

including auto regulation.

Ventricular distortion / CSF obstruction

Midline shift

Perilesional edema - makes tumor functionally bigger

Contrast enhancement - degree of BBB disruption

Proximity to venous sinuses - blood loss

Preoperative assessment INVESTIGATION

ASA physical status ????

Nature of surgery

High incidence of systemic involvement – CN

palsies, motor/ sensory involvement

Higher comorbidities

Poor surgical outcome

Premedication1. Sedation -Risk assessment, individualised

- often avoided

2. Others - Continue anticonvulsants, antihypertensives,

steroids till morning of surgery

- mannitol, furosemide

Sedation - hypoventilation (hypercapnia, hypoxia, airway obst )

Sedation - ↓stress→↓ICP→↓ vasogenic edema

Vascular access1. Intravascular

a) 2 large bore i.v cannulas

b) CVP -VAE (diagnostic + therapeutic )

- vasoactive drugs

2. Arterial canulation

a) NIBP (anticipated blood loss)

b) ABG

c) Hypotensive anaesthesia

Monitoring

1. ECG, HR – myocardial ischemia, arrhythmias

2. SpO2

3. ETCO2

4. NIBP/ IBP – at level of operative field

5. NMT – on non hemiplegic limb

6. Temperature

7. CVP

8. Urine output

9. Precordial doppler, TEE, ETN2

10. ICP – currently rarely used, except in neurotraumatology

UMN lesion ↑ Ach receptor density

Resistance to NDMR

Induction GOALS – Normotension, Normocarbia, Normoxia

Preoxygenation

P/M – opioid (fentanyl 1-2 μg/kg , morphine 0.1 mg/kg)

I/W – Thiopentone (3-5 mg/kg) Propofol (1.5 – 2.5 mg/kg)

Myorelaxation – Sch (transient ↑ ICP) Use intermediate acting relaxants Atracurium – histamine release ( cerebral vasodilatation) Vecuronium, Rocuronium – commonly used

Only after adequate muscle relaxation achieved, perform quick + gentle laryngoscopy

Intubation – armoured ETT Tape on opposite side of surgery Bandaging may ↓cerebral venous return

Controlled ventilation

Lignocaine , Esmolol, 2nd dose of i.v induction agent

60-90 sec earlier

Positioning GOAL- Slow and gentle positioning with 15- 20 ⁰

head up tilt to aid cerebral venous drainage

Verify cautiously – 1. All potential pressure points padded

2. Eyes protected & padded

3. Peripheral pulses palpable

4. Nerve compression absent

5. Ventilation adequate ( PEEP, ETT position)

ETT – Kinking in post. Oropharynx

Advancement / extubation

Neck – Extreme rotation / flexion may cause ↑ ICP,

quadriparesis, tongue swelling

Head pins – Adequate plane of anaesthesia

Local infiltration / bolus opioid (fentanyl)

Dural opening in presence of high ICP –

- sudden decompression & transcalvarial herniation

- herniated tissue cannot be interposed back

- permanent neural damage

ICP to be brought within normal limits before opening the dura.

Methods – head elevation, mannitol, furosemide, CSF drainage

Optimization of ICP

Mannitol (20%)

Hyperosmolar agent

Dose : 0.5 – 2 mg/kg i.v. (0.5-1 mg/kg over 15 min just before

opening dura)

Action reaches peak at 20-30 min.

Advantages : Draws water from brain (↓ brain bulk)

↓ Hct (↑CBF , O2 delivery)

Disadvantages: 1.If given fast, it transiently ↑ blood vol. &

may cause CHF , pulmonary edema

2. Hypokalemia

3. Worsen C. edema if BBB disrupted

Optimize ICP (cont…)

Optimize ICP (cont…)

Furosemide

Loop diuretic (Na K 2Cl channel blocker)

Dose : 0.5 – 1 mg/kg i.v.

use : sole agent to ↓ ICP

adjunct to mannitol

Mannitol draws fluid out of brain & lasix discards it through kidneys

Optimize ICP (cont…) CSF drainage

1. Lumbar subarachnoid drainage system

2. Ventriculostomy drain (EVD)

(connected by tubing to a CSF collection device which can be elevated or lowered)

CSF drainage (↑ICP, aneurysm / ENT surgeries) ICP measurement

CSF drainage – Slow– bolus ≤ 20-30 ml

Complications – hematoma formation– infection– if abrupt ↓ICP – aneurysmal rupture

MaintenanceGOAL- Maintain cerebral homeostasis + Aid “slack” brain.TARGET – Anaesthetic agent , Fluid therapy, Neuroprotection strategies.

ANAESTHETIC AGENT

VOLATILE ANAESTHETIC

I.V. ANAESTHETIC

PROS 1. Easy, 2. Extensively available

1. Intact CBF – CMRO2 coupling

2. ↓brain bulk3. Propofol blunts N2O

cerebrostimulation

CONS 1. CBF – CMRO2 uncoupling

2. ↑ICP

1. Short acting

RECOMMENDATION 1. Use in short, uncomplicated surgeries

2. At < 1.5 MAC3. Avoid combination

with N2O

1. Use in cases with high risk of ↑ICP/ brain bulk

Maintenance (cont…)

FLUID THERAPY

Principle – BBB is selectively permeable

Water crosses freely, most ions (Na+) don't.

If BBB disrupted (ischemia, head injury, tumors) – hyperosmolar agents may

↑brain water instead of drawing water out.

RECOMMENDATIONS (FLUID RESTRICTION)

1. FLUID LOSS – Do not replace fasting / III space losses

2. BLOOD LOSS – Assessment difficult (drapes + continuous irrigation)

3. SERUM OSMOLARITY –

Maintain at 305- 320 mosm/L

Give NS (309 mosm/L)

Avoid RL (272 mosm/L)

Use them alternately

Avoid glucose containing solutions (5%D , DNS)

Mannitol (0.5 – 2 mg/kg)

Furosemide (0.5 - 1mg/kg)

Maintenance (cont…)

NEUROPROTECTION

a) PaO2

b) PaCO2

c) BP (sympatholysis,

antihypertensives)

d) Glucose ( <170 mg/dL )

e) Temperature ( controlled

hypothermia 32-34 C)⁰

f) Analgesia

g) Adequate depth of anaesthesia

Maintenance (cont…)

OTHERS

a) Seizure prophylaxis/ control

b) Steroids

c) Nimodipine (SAH)

d) Barbiturates

e) Magnesium (experimental)

The chemical brain retractor concept

Mild hyperosmolality

Adequate head-up positioning

Lumbar cerebrospinal fluid drainage

Intravenous anesthetic agent (propofol)

Avoidance of brain retractors

Venous drainage: jugular veins free

Maintenance (cont…)

Emergence Most important but often neglected

“ A well planned procedure is often rewarded by a fully awake patient who is appropriately responding to verbal commands and neurological examination.”

Due to pain and shivering, associated with

• ↑ catecholamine release

• ↑ O2 Consumption ( X 5 times)

AIMS

To maintain intra + extracranial homeostasis

(MAP- CPP- CBF- ICP- CMRO2 - PaO2 - PaCO2- temp)

Avoid intracranial bleed ( coughing, ventilator fight)

Emergence (cont…)

EARLY AWAKENING LATE AWAKENING

1. Early neurological examination & reintervention

2. Less ↑BP/ catecholamine burst

3. ↓ cost of postop care

1. Less risk of ↓O2,↑CO2

associated with anaesthesia hangover

2. Better respiratory & hemodynamic control

RECOMMENDATION – Early awakening is recommended unless contraindicated.

Checklist for early extubation

1. Good preop GCS (>8)

2. CVS stability + normothermia + normoxia

3. Limited brain surgery, no major brain laceration

4. No extensive post fossa manipulation ( CN 9 – 12)

5. No major AVM removal

Emergence (cont…)

Indication of late extubation

1. Low GCS

2. Inadequate airway control

3. Intraop catastrophe

4. Brain edema/ deranged cerebral homeostasis

(long duration/ extensive/ repeat surgery)

5. Surgery around vital areas

Emergence (cont…)

Immediate postoperative concerns

1. Failure to awaken

Nonanaesthetic causes – seizures, cerebral edema,

intracranial hematoma, pneumocephalus, vsl occlusion,

metabolic/ electrolyte disturbance, herniation.

Anaesthesia hangover – opioid, volatile anaesthetic,

muscle relaxant.

Immediate postoperative concerns (cont….)

2. Post operative care

a) Head end elevation (15-30⁰)

b) Adequate ventilation & oxygenation

c) Monitoring of neurological function

d) Check for serum electrolytes and osmolarity (mannitol, frusemide

to continue)

e) Seizure prophylaxis (phenytoin / fosphenytoin)

f) Seizure treatment (thiopentone 50-100 mg, midazolam 2-4 mg ,

lorazepam 2 mg)

Immediate postoperative concerns (cont….)

g) SIADH

Hyponatremia, S. hyposmolarity, high U. osmolarity

T/T restrict free water intake

h) DI

After pituitary surgery

Hyponatremia, S. hyposmolarity, low U. osmolarity

T/T ↑ water intake, vasopressin , desmopressin

i) Tension pneumocephalus

Skull X ray / CT

T/T opening the dura

Concerns for posterior fossa surgery

1. Presentation

Cranial nerve palsies (IX, X) may impair gag reflex-

aspiration

Hydrocephalus

Cerebellar dysfunction

Edema in floor of fourth ventricle- damage to resp. centers

2. Cardiovascular instability

Bradycardia and hypertension – due to V nerve stimulation

(resolve with cessation of stimulus)

Bradycardia, asystole/ hypotension- due to IX/X nerve

stimulation

3. Sitting positionAdvantages

– Better surgical exposure– Improved venous/CSF drainage– Low bleeding– Improved access to airway, chest

Disadvantages– VAE– CVS instability

Concerns for posterior fossa surgery

1. Trans-sphenoidal resection through nasal/ labial incision

2. Endocrine manifestations- normo/hypo/ hyperpituitarism

3. ICP is not a concern due to small size of tumor

4. Uncontrolled bleeding is rare

5. Throat pack to prevent blood from accumulating in stomach /

aspiration

6. Nasal breathing obscured by postoperative nasal packs.

Concerns for pituitary surgery

1. Miller’s anaesthesia.Ronald D Miller. 7th ed.

2. Stoelting's Anesthesia and Co-Existing Disease, 5th ed.

3. Handbook of neuroanaesthesia. James E Cottrell. 4th

ed.

4. Clinical anaesthesia procedures of massachusettes

general hospital. 7th ed.

5. Morgan’s clinical anaesthesiology.4th ed.

References

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