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Head Trauma in Neuroanesthesiology BW Handout

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					Head Trauma in Anesthesiology
Jamison Elder MD Dept. Anesthesiology

Objectives:
Timely Informative Practical Enjoyable

Lecture Information
Board Review Sources
– – – – – – Sdrales & Miller, Anesthesia Review, 1st Ed Faust, Anesthesiology Review, 3rd Ed Morgan & Mckahil, Anesthesiology, 3rd Ed Mckahil, Roizen, Essence of Anes Practice, 1st Ed Roizen, Derchwitz, MGH Board Review Anes, 5th Ed Derchwitz, Hall, Anesthesia Comprehensive Review, 2nd Ed

Head Trauma
Epidemiology

Epidemiology Head Trauma
Epidemiology
– 500,000/yr – 30y/o, 2M:1F – Mortality (40%)
15% Field 25% Hospital

Epidemiology Head Trauma
Injury Type
– – – Diffuse Lesion 48% SDH 24% EDH 3%
91% Skull Fx

– Morbidity (40%)
40% CNS Disabled

– Full Recovery (20%)

Mortality

Morbidity

Recovery

Diffuse Lesion EDH DAI

SDH ICH

– ICH 6% – DAI 3%

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Head Injury

Head Trauma
Types

Head Injury
– Types? – Hallmark? – CNS Measure? – Imaging?

Types: Closed Head Injury
Diffuse Axonal Injury Subdural Hematoma Epidural Hematoma
– Dura OPEN

Types: Head Injury
OPEN Head Injury
ICP = 0 CPP = MAP - CVP

CLOSED Head Injury
– Dura CLOSED
ICP > 0 CPP = MAP - ICP

Hallmarks: Closed Head Injury
Hallmark of CHI?
LOC LOC ≅ Severity

S/Sxs ⇑ ICP: S/Sxs
N/V/HA MS changes Ataxia Seizure Coma Death

Head Trauma
Measures

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Measures: Head Injury
Measures of Injury
– LOC – GCS – ICP
Bolt Epidural Sub-dural SubIntra-ventricular Intra-

Measures: Glasgow Coma Scale
Eye Opening (4 eyes)
4 Spontaneous 3 Verbal 2 Pain 1 None

Motor (Six Shooter)
6 Verbal 5 Localize 4 Flexion/Withdrawal 3 Decorticate (Flex) 2 Decebreate (Ext) 1 None

Verbal (Best Response)
5 Oriented 4 Disoriented 3 Inappropriate 2 Incomprehensible 1 None

– Imaging
CT (1st line)

GCS

CT

Measures: Glasgow Coma Scale
Useful GCS Values
– – – – <8 ≅ 35% Mortality < 8 ≅ Intubation >12 ≅ Local/MAC? <12 ≅ GETA – – – –

Measures: Closed Head Injury
CT Findings ⇑Morbidity
>5mm Midline Shift >25cc Lesion DAI Pattern Herniation

Physiology Head Trauma
Intracranial HTN CBF Autoregulation Cerebral Ischemia Pharmacology

Head Trauma
(ICP) Intracranial Pressure

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Physiology in Head Trauma
ICP Components
– – – CSF 5-15% 5Blood 3-5% 3Brain 80-85% 80-

Physiology in Head Trauma
Intracranial Compliance
– Fixed Box – Monro-Kellie Hypothesis Monro-

CSF Composition
– ≅ Na – ⇑ Mg, Cl – ⇓ Colloid, K, Ca

ICP Buffer System
– – – – 1st CSF Translocation 2nd CSF ⇓net production 3rd Blood Translocation 4th Brain Herniation

Physiology in Head Trauma
ICP Values
– – – – Nml < 15 Abnml > 20 Reversible ≅30-40 30Irreversible >60

Head Trauma
Physiology

⇓ Compliance
– Cardiac Oscillations – Plateau Wave

Physiology in Head Trauma
CBF Autoregulation
– Definition? – Mechanism? – Influences? PaCO2 PaO2 CMR ∆P (MAP, ICP) (MAP, Rx (Pharm) (Pharm)
– Normal:

Physiology in Head Trauma
CBF Autoregulation
CPP 50-150 50PaCO2 ≅40 Pa02 >50

– Shifted Leftward
Chronic HTN (1-2mo) (1+/- 20% MAP +/-

– Extremes
MAP drives CBF

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Physiology in Head Trauma
CBF Influences
– PaCO2
Most Influential
– 20-80mmHg 20-

Physiology in Head Trauma
CPP PaCO2 PaO2

Comparison:
CPP PaCO2 PaO2

250 200 150 100 PaO2 50 PaCO2 CPP 0 25 50 50 100 150 200 0

Hyperventilation
– Best @ 25-30 25– Worst @ <20

– PaO2

>60 mmHg Wnl <50 mmHg Abnml Associated Injury

Physiology in Head Trauma
CMR02 60% 40% CBF Influences:
– Temperature ∝ CMR02
60% Functional CMR
– TEMP & Rx

Physiology in Head Trauma
Hypothermia & Ischemia
Temp Fxnl CMR Basal CMR Time 37 C 60% 40% 5min 27 C 17 C 25% 0% 16% 8% 60min 60
40 20 0 37 C 27 C 17 C Fxnl CMR Ischemia (min) Ischemia (min) Fxnl CMR Basal CMR

40% Basal CMR
– TEMP

– CMR02

Demand = 3-4cc/100g/min 4cc/100g/min Supply = 50cc/100g/min 50cc/100g/min No stored reserve of 02 ⇓⇑CMR 7% ≅ ⇓⇑ 1 C TEMP ⇓⇑CMR

Basal CMR

Michenfelder, The Awake Brain, 1988

Pharmacology Head Injury

Head Trauma
Pharmacology

Rx Influences on CBF:
– Nitrates (SNP) – Volatiles (HAL, ENF) – Hypnotics
STP Ketamine

– MISC.
Nitrous Oxide Droperidol + Fentanyl

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Pharmacology Head Injury
NITRATES (SNP):
– Vasodilator – ⇓ CPP – ⇑ ICP – Rebound HTN – Toxicity
Bolus 0.5mg/Kg/hr Gtt 0.5mg/kg/24hr
Cottrell, J. Neurosurgery, 48:329, 1978

Pharmacology Head Injury
Volatile Agents:
– “Uncoupling Effect” Effect”
⇓ CMR & ⇑ CBF

CPP w/ Induced Hypotension by SNP

120 100 80 CPP 60 40 20 0 No SNP No SNP SNP SNP

MAP ICP CPP

– Critical CBF
ISO>>HAL>>ENF

– Halothane
Potent C. Vasodilator ⇓ MAP (⇓CO & ⇓SV) (⇓

– Enflurane
Net ⇑ CSF

Pharmacology Head Injury
(STP) Na Thiopenthol: Thiopenthol:
– Mechanism: (⇑GABA) – Indications:
Direct Vasoconstriction ⇓ CMR02 Focal >> Global Injury

Pharmacology Head Injury
Lidocaine/Propofol/Etomidate
– Vasoconstriction – ⇓ CMR02

Ketamine (⇑SNS)
– Vasodilator – ⇑ CMR02

– EEG:Burst Suppression:
Suppressed 30mg/Kg Slowed 5-10mg/Kg 5-

Nitrous Oxide
– Vasodilator (weak)

– Side Effects:
⇓ MAP (⇓SV & ⇓CO) Cloud Neuro Exam

Opiods
– No Effect

– NOT Impair CBF or PaCO2

Droperidol + Fentanyl
– ⇓ CMR02 (weak)

Cerebral Ischemia Head Trauma

Head Trauma
Cerebral Ischemia

Mechanism:
– CPP = MAP - ICP
ICP (IC HTN) CVP (CHF) MAP (Hypotension)

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Cerebral Ischemia Head Trauma
⇑ ICP S/Sxs: S/Sxs:
– – – – – – – N/V HA MS Changes Ataxia Seizure Coma Death

Cerebral Ischemia Head Trauma
Succinylcholine & ⇑ICP:
– Mechanism: Fasciculations – Dose: 1.6mg/Kg – Transient Effects:
1mg/Kg = ⇑ICP 5-10mmHg 5Cough = ⇑ICP 20-40mmHg 20-

– ⇑ICP Blunted by:
10% NDNMJB STP (3-5mg/Kg IV) (3Volatile (>1MAC)

– “ABC before G” G”

Cerebral Ischemia Head Trauma
Dextrose IVF:
– – – Anaerobic Glycolysis Free Water Neurotoxic

Cerebral Ischemia Head Trauma

Positioning:
MAP @ Circle of Willis (ear) Feet = Heart Neck Flexion Venous Obstruction

Contraindicated!

Cerebral Ischemia Head Trauma
Corticosteroids:
– Mechanism??? Mechanism???
Stable Membranes (BBB) ⇓ CSF Production

Cerebral Ischemia Head Trauma
Optimal Mgmt:
– 1st ⇑ CPP
⇑ MAP ⇓ ICP ⇓ CMR

– Indications:
Yes - Spinal Cord Edema (Focal) No - Cerebral Edema (Global)

Dexamethasone & Methylprednisolone

– Side Effects:
Adrenal crisis

– 2nd Reverse Etiology – 3rd Neuro-Protection Neuro-

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Cerebral Ischemia Head Trauma
CPP Calculations:
– Normal > 60 mmHg – MAP @ Cir. of Willis – CPP = MAP – (ICP or CVP)
Dura OPEN CVP Dura CLOSED ICP 20% Baseline MAP

Cerebral Ischemia Head Trauma
Neuro-Protection: Neuro– 1st CPP Optimized
⇓ICP & ⇑MAP

– 2nd ⇑Pa02
Fi02 & Hgb

– 3rd PaCO2
Hyperventilation

– 4th ⇓CMR02

MAP CPP ICP or CVP

STP Temperature

– 5th Free Radical Scavenger
Mannitol

Cerebral Ischemia
Mannitol:
– Mechanism: Osmotic Diuretic – Dose: 0.25-1.0g/Kg/4hr 0.25- 1.0g/Kg/4hr
Ceiling Effect VS Clinical response

Head Trauma
Peri-Operative Concerns

– Derangements (>2g/Kg):
Early: ⇑Volume (CHF) Late: ⇓Volume, ⇓K, ⇑Na SDH (Elderly) +/- Cerebral edema (BBB) +/IVF (1:1 UO w/ IsoCx) IsoCx) Electrolyte Prn

Bridging Vein

Peri-Op Head Trauma
Co-Existing Disease: Co– Geriatrics
Cortical Atrophy ⇒ SDH

Peri-Op Head Trauma
Anesthetic Concerns:
– Airway Mgmt
Full Stomach Difficult Airway

– Cardio/Pulmonary
COPD, OSA CAD, CHF, EKG ∆s

– PVD
CVA (<4-6wks) (<4ICA Bruit (60% Asx Stenosis) Stenosis)

– Intracranial HTN – Emergence Based
Pre-Medication PreIntra-Op Exam IntraPost-Op Exams Post“Yep, Dr Elder! You sure did! That’s enough exercise for today.” That’ today.”

– DM – CRI

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Associated Injuries of CHI
Associated Injury:
– – – C-Spine Fx (10%) Basilar Skull Fx SNS Surge Injury
EKG ∆s (injury) Pulmonary Edema (V/Q Mismatch)

Peri-Op Complications
Peri-Op Complications PeriVAE Shock/Anemia Inflammatory
– Coagulopathy/DIC/SIRS/ARDS Coagulopathy/DIC/SIRS/ARDS

(DI) Diabetes Insipidus Hyperosmolar Non-ketotic Coma NonBasilar Skull Fx Vasospasm Sitting Craniotomy
– Pneumocephalous – Nerve Injury – VAE

– Shock

Autonomic Hypereflexia

Peri-Op Complications
(VAE) Venous Air Embolism:
– Risk: Head Up >5° >5° – SXs: murmur, arrhythmia, ⇓BP, ⇓PaCO2, SXs:
⇓02sat, ⇑PaN2

VAE Detectors

Increasing Sensitivity

– Monitors:
TEE(0.01cc)>>PCD(0.5cc)>>PAP>>etN TEE(0.01cc)>>PCD(0.5cc)>>PAP>>etN 2=etCO2>EKC>Auscultation

– Tx: Tx:
Notify Surgeon Flood Field Head down IJ Compression Volume & Ionotropy Air Aspiration

Rate of Air Entrapment (cc/Kg/min)
Rusner, Head Trauma - Origin and Evaluation of Plateau Wavews J. Neurosurg 60: 312-324 1984

Peri-Op Complications
Sitting Craniotomy:
– Nerve Injury
C-Spine Sciatic Pernoneal/Ulnar

Peri-Op Complications
Autonomic Hypereflexia
Why? Dysfunctional SNS Response When? >4-6wks s/p spinal shock >4Where? <T6 Spinal Shock (>T10 Unlikely)
– Sxs: Sxs:
Early: Pulm Edema, ⇓SVR Late: HTN, Bradycardia, LV Dysfxn, Bradycardia, Dysfxn, Poikilothermia, Vasodilate >lesion Poikilothermia, Cutaneous or Visceral Stimulation I wish my Brain could see this?

– Airway Edema
Venous Egress

⇑SVR ⇑SVR

– Pneumocephalous
MS∆s, HA MS∆ Tension (N20)

– Tx: Tx:
Pentolamine (α1 Antagonist) Trimethaphan (Ganglion (SNS) Blocker) β-Blockers Avoided (Unopposed α1)

⇑HTN

– VAE

Vasodilate Rhinorrhea

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Peri-Op Complications
Vasospasm s/p SAH:
– Hallmark:
New MS∆s or LOC POD 4-14

Peri-Op Complications
Diabetes Insipidus: Insipidus:
– Mechanism:
⇓⇓⇓ ADH Pituitary Injury

– Treatment:
DDAVP
– 5-10mg Nasal Spray bid

– Imaging:
Severity ∝ Vol. of Blood Angiographic Signs 70% Clinical Sxs 20-30%

– 2 mcg SQ or IM q12h

– Dx: Dx:
Polyuria (>3-4cc/kg/hr) (>3– No Glucosuria

Vasopressin
– 5-10U SQ q4hr

– Tx:
Triple “H” Therapy Nimodipine Angioplasty

⇓Uosm (<1.005) ⇑Sosm (>300)

– Mgmt:
UO Replacement Free Water Deficit

Peri-Op Complications
Brain Death (Definition = 3 Parts)
– 1. Cortical

Summary:
Board Review Material:
– – – – – – – – Demographics Types CHI CBF Autoregulation Cerebral Ischemia ICP Management Pharmacology Associated Injuries Complications
“Sorry, Dr. Elder, only senior management is allowed to go on the warpath”

Brain Dead?

Irreversible LOC No purposeful Motor Fxn

– 2. Brainstem
Irreversibly Loss of CN Reflexes
– Pupillary, Corneal, Oculovestibulo, Oropharyngeal, Respiratory

– 3. Study
No ∆ to Atropine No RR to PaCO2 >60 torr

No Mimics (Metabolic, Rx, Hypothermia)

The End

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