Pediatric TBI

Heather Patterson

PGY -3

April 29 2008

• Classification of TBI• Primary and secondary injuries

– Definitions – Physiology

• Airway management– When to intubate– Premedication

• Management of increased ICP and neuroprotective strategies

TBI: Objectives

TBI: Classification

• Mild– GCS 13-15

• Moderate– GCS 9-12

• Severe– GCS <9

TBI: Classification

• Primary:– Initial irreversible injury caused by

mechanical disruption• Direct:

– Impact of object with skull– Damage occurs directly beneath involved area or

through propagation of impact injury

• Indirect:– Cranial contents are set in motion within the skull– Acceleration/deceleration injuries tearing of

vessels and disruption of axonal integrity

TBI: Classification

• Secondary:– Occur in the post-traumatic period

• Ischemic injuries resulting from physical or metabolic insults

• Ie decreased CPP, hypotension, hypoxia, anemia, seizures, elevated ICP

• This is where our current management strategies are targeted***

TBI: Classification

• We know these are bad…– Hypotension– Hypertension– Hypoxia– Seizures– Anemia

• How bad are they?

TBI: Secondary injury

• ICP > 20 mmHg– Autoregulation is lost, ICP affects CPP

• CBF then depends directly on MAP– when ICP reaches systemic pressures,

CBF ceases

• Increased blood volume and tissue edema initially following injury contributes to cerebral edema and worsening ICP

TBI: Secondary injury - ↑ICP

• TBI patients with post resuscitation GCS <8

• Hypotension (SBP < 90 mmHg) – 35% of patients– 150% increase in mortality

• Hypoxia (PaO2 < 60)– 45% of patients– significantly increased mortality

• Hypotension + hypoxia– 23% – Double mortality rate

TBI: Secondary injury -hypotension

Chestnut et al. J Neurosurg 1990

• Brain consumes 20% of body’s oxygen supply, and requires 15% of cardiac output

• CBF = CPP/CVR

• CPP = MAP – ICP– CPP normally varies b/w

70-100 mm Hg

TBI: Physiology

Cerebral Autoregulation

• Monro-Kellie Doctrine– Brain + blood + CSF + mass =

constant volume

• ICP maintained at constant level – …… to a point

TBI: Autoregulation

• Autoregulation:– Maintenance of CBF within a

MAP range of 60-150 mm Hg

– Tightly controlled by cerebral vascular resistance

– Mainly unaffected by fluctuations in systemic BP or ICP in non-injured brain

TBI: Physiology

Cerebral Autoregulation

• CPP = MAP – ICP– High ICP = bad– Low MAP = bad

TBI: Autoregulation

• Initial pattern:– Cerebral blood flow decreases in children – Increased metabolic demand– Impaired autoregulation - CPP is dependent on

maintaining adequate blood pressure – Release of excitatory neurotransmitters such as

acetylcholine, glutamate, and aspartate causes neuronal damage

• Cerebral swelling develops and peaks 24 to 72 hours after the injury. – More common among infants and children vs

adults • Mech unknown, ? Anatomical, ?pathophys

– Further compromise to cerebral perfusion leads to more ischemia, swelling, herniation, and death.

TBI: Pediatric Physiology

Uptodate.

• 8yo male • ATV, no helmet, rolled, hit head on

rocky ground• GCS 9 on EMS arrival• Became more alert during

transport

Case:

• ED arrival:– Afeb 140s 30 100/70 89% NRB– What is your initial approach to this

patient?• ABCs• Avoid causes of secondary injury

– Neuro:• Opens eyes with pain• Moans to pain• Flexor posturing L upper extremity

– What is your GCS?

Case:

• What are the indications for intubation in this patient?

• What drugs would you like to use?

• What about his neck?

Resuscitation: Airway/Breathing

• Always ensure C-spine immobilization– 6-8% of serious TBI and 3.6% of mild

TBI patients have C-spine injuries– Up to 14% of patients with GCS 3-5

have C1 or C2 fractures

C-Spine

• Inability to maintain or protect the airway

• Inadequate ventilation or oxygenation

• Hemodynamic instability• Projected clinical course• Excessive combativeness

Indications for Intubation:

• Laryngoscopy & intubation well shown to increase:– Heart rate (11-28 bpm)– Blood pressure (25-28

mmHg)

• Mechanisms not well understood– Reflex sympathetic response– Catecholamine release

Response to intubation: HR & BP

• Laryngoscopy & Intubation Increase ICP

1. Valsalva & cough reflex• Well described to increase ICP

2. Independent reflex mechanism• ICP increased ~6-16 mm Hg with

laryngoscopy & intubation in paralyzed patients

• Mechanism poorly understood– Hamill J. et al. Anesthesiology 55: 578-581

3. Increased HR and BP = pressor response - increased CBF

Response to intubation: ICP

1. Avoid Hypotension– Cerebral Ischemia– Increases mortality

2. Avoid Hypertension– Cerebral edema

• Increased capillary hydrostatic pressure

– Increases ICP• increased cerebral blood volume

– Increases hemorrhage and hematoma

Physiologic Goals of Intubation:

3. Avoid Hypoxia:- Cerebral ischemia

Physiologic Goals of Intubation:

• Ideal meds:– Don’t cause hypertension

and tachycardia– Don’t cause hypotension– Don’t increase ICP

Premedication:

Opioids

Premedication: Opioids

• Attenuates pressor response (↑HR/BP)– Higher doses cause hypotension

• No evidence about effect on ICP during intubation

• No evidence about neurological outcomes

Premedication: Opioids

• RCT N=60– Saline– lidocaine 2/kg– Alfentail 15/kg– Alfentanil 30/kg

• Looked at HR, BP

Premedication: Opioids

• Saline & lidocaine– No effect on response

to laryngoscopy

• Alfentanil– Both doses blunted

response to laryngoscopy

• Alfentanil 15– most stable

• Alfentanil 30– significantly lower

MAP

Premedication: Opioids

Circulatory responses to laryngoscopy: the comparative effects of placebo,

fentanyl and esmolol. Can J Anaesth. 1989

May;36:301-6.

• Randomized Controlled Trial– N=60

• Placebo• Esmolol

– 500ug/kg/min x 6 min) then 300ug/min x 9 minutes

• Fentanyl– 0.8ug/kg/min x 10 minutes

Premedication: Opioids

• Results– Esmolol

• Blunted HR response• Pressures unchanged or increased

– Fentanyl• Decreased HR below baseline• Decreased sBP, dBP, MAP

• Conclusions– Fentanyl more effective at blunting HR response– Esmolol more effective at maintaining perfusion

pressures

Premedication: Opioids

Which drug prevents tachycardia and hypertension associated with tracheal intubation: lidocaine, fentanyl, or esmolol?

Anesth Analg. 1991 Oct;73(4):502-4.

• RCT– N=80

• Thiopental induction followed by– Placebo– Lidocaine 200mg– Fentanyl 200ug– Esmolol 150mg

• Sux 1-1.5/kg and intubation performed

Premedication: Opioids

Results

• Heart rate– Similar increases for

• placebo (44% +/- 6%)• lidocaine (51% +/- 10%)• fentanyl (37% +/- 5%)

– Lower for esmolol (18% +/- 5%) (P < 0.05)

• Blood Pressure– Attenuated pressor response vs placebo (36%

+/- 5%) in• lidocaine (20% +/- 6%)• fentanyl (12% +/- 3%)• esmolol (19% +/- 4%)

Premedication: Opioids

• No study on opioids and ICP during intubation

• ICU studies showing– Increased ICP– Decreased ICP– Variable effects on MAP

Premedication: Opioids

• Attenuates pressor response (↑HR/BP)• Higher doses cause hypotension• No evidence about effect on ICP during

intubation• No evidence about neurological outcomes

Premedication: Opioids

Lidocaine

Premedication: Lidocaine

• Systematic review of literature• No ED data for RSI

– Elective NSx pts and suctioning

• Looked for hard outcomes increases in ICP and neurological outcomes

• Conclusion:– no good evidence to support use of

lidocaine as pretreatment for RSI

Premedication: Lidocaine

In patients with head injury undergoing rapid sequence intubation, does pretreatment with intravenous lignocaine/lidocaine lead to an improved neurological outcome? A review of the literature.N Robinson,M Clancy Emerg Med J 2001;18:453–457

Rapid sequence intubation in adults with elevated

intracranial pressure: a survey of emergency medicine

residency programs.Am J Emerg Med. 1997

May;15(3):263-7.

• USA– IV lidocaine routinely administered

• UK– Survey of 4 EDs over 28 days– 60 RSI’s– 17 for head injury– No patient received lidocaine

• Canada:– Retrospective chart review in Vancouver– TBI RSI in ED

• 84% got lidocaine• 33% got fentanyl

Premedication: Lidocaine

Kuzak et al 2006 CJEM

• POSITIVE STUDY

• 20 patients going for elective neurosurgery– All received morphine, diazepam, atropine 1 hour prior to

induction– NOT TBI– NOT PUBLISHED

• Randomized to lidocaine 1.5/kg or saline

• Induction with thiopentone, sux

• Results– Lidocaine blunted ICP rise vs saline– Difference of 12mmHg (p<0.05)

Bedford R, et al. Lidocaine prevents increased ICP after endotracheal

intubation. In: Shulman K, et al, eds. Intracranial Pressure IV. Berlin: Springer,

1980: 595-8.

Premedication: Lidocaine

• NEGATIVE STUDY

• 22 patients - elective neurosurgery• tumor or aneurysm clipping

– Randomized to lidocaine or esmolol– No control arm

• Induction with thiopentone, fentanyl, vecuronium, isoflurane

• Measured ICP and MAP Prevention of increase of blood pressure and intracranial pressure during endotracheal intubation in neurosurgery: esmolol versus

lidocaineSamaha T. et al. Ann Fr Anesth Reanim.

1996;15(1):36-40. (French)

Premedication: Lidocaine

– ICP rose after intubation• 10 +/- 6 to 16 +/- 9 mmHg (p<0.05

– CPP decreased before intubation• 96 +/- 12 to 68 +/- 15 mmHg (p<0.05)

– CPP rose after intubation• 99 +/- 17 mmHg (p<0.05)

Premedication: Lidocaine

Intravenously administered lidocaine prevents intracranial hypertension during endotracheal

suctioning.Donegan, M. Anesthesiology. 1980

Jun;52(6):516-8.

• POSITIVE STUDY:

• RCT – Crossover trial– N=10 ventilated head injured patients in ICU

• All received– Moderate hyperventilation (old school)– Dexamethasone (old school)– Mannitol– 5/10 received pentabarbital

Premedication: Lidocaine

• Methods– Lidocaine 1.5mg/kg vs saline

• Results – ΔICP– Before suctioning

• Lidocaine 17 →10 (p<0.05)• Saline 17 → 16 (NS)

– After suctioning• Lidocaine 10 → 16 (NS)• Saline ICP 16 → 27 (Sig)

– No change in MAP

Premedication: Lidocaine

A randomized study of drugs for preventing increases in intracranial pressure during endotracheal suctioning.

White PF, et al. Anesthesiology. 1982 Sep;57(3):242-4.

• NEGATIVE STUDY:• RCT

– N = 15 - ventilated head injured patients in ICU– Receiving dex, mannitol, hyperventilation (old

school)– Monitored 5 min pre/post and during suction

• Received one of: (multiple iterations)– Saline – 2ml– Fentanyl – 1ug/kg– Thiopental – 3mg/kg– Lidocaine – 1.5mg/kg– Succinylcholine – 1mg/kg

Premedication: Lidocaine

• ΔICP – Lidocaine

• +4 (+/-2) mmHg (no different than saline)– Succinylcholine + Fentanyl

• Significantly attenuated ICP rise

• MAP & CPP– No differences among groups

Premedication: Lidocaine

Safety and Efficacy of Intravenous Lidocaine During Intubation of Head Injury Patients: a Systematic Review and Meta-Analysis.

Vaillancourt C, Kapur A, Stiell IG, Wells GA. CAEP 2002 - Abstract

• Structured meta-analysis

• 55 journal articles identified

• 2 articles reported ICP– one positive article, one insufficient data

• 24 report MAP– Mean decrease -6.6 mmHg (2.1-11.2)

Premedication: Lidocaine

• SUMMARY:– Small number of poor studies

– No RSI info. Populations included: • Elective neurosurgery• Tracheal suctioning in ICU

– Contradictory effects on ICP

– Decrease MAP

Premedication: Lidocaine

• Defasciculating dose of NMB will attenuate a succ induced rise in ICP

• No clinical correlation of fasciculations with increased ICP

• Reasonable to use a defasciculating dose or a non-depolarizing NMB

• Variable use – staff to staff

Premedication: Defasciculation

• Thiopentol 3-5mg/kg

• Etomidate 0.3mg/kg– Not often used in children

• Ketamine currently not used for head injury.

Induction Agents:

• After you successfully intubate your patient, the RT asks you how quickly you would like him to bag.

• pCO2 goals:– Normocarbia (pCO2 35-38)

• ↓pCO2 causes cerebral vasoconstriction and may limit CBF causing secondary injury

– Avoid prophylactic hyperventilation• 24hrs post injury, CBF~GCS(II) PaCO2 further CBF in first 24hrs

– Aggressive hyperventilation (PaCO2<30)• Clinical signs of herniation

Resuscitation: Airway/Breathing

• What are your BP goals for this patient?• Maintain BP

– Goal: systolic >5th% for age, no clinical shock• 70mmHg + 2 x age (>1yr)• Maintain CPP, prevent secondary ischemia

– Hypotension peds mortality rate (II)

• Volume resuscitation– Isotonic fluids (NS, Ringer’s)– No hypotonic fluids (free watercerebral

edema)– PRBC –need to maintain O2 delivery

• Secondary injuries blood loss

Resuscitation: Circulation

• You successfully resuscitate the patient in the trauma bay and take them to CT for imaging.

Case

• Back in ICU the patient suddenly becomes hypertensive and bradycardic.

• His pupils look like this:(just pretend he is 7years old!)

Case

• Uncal Herniation– Most common– Compression of ipsilateral uncus of the

temporal lobe into the infratentorial compartment

– CNIII:• Pupil dilated and nonreactive

– Compression of brainstem:• Contralateral hemiparesis/posturing• Bonus question: what if you get ipsilateral motor

findings?

TBI: Herniation Syndromes

• Central Transtentorial• Expanding lesion at frontal or occipital pole;• Bilateral central pressure from above causing• ALOC, bilateral weakness, pinpoint pupils, increased

tone

• Cerebellotonsillar• Cerebellar tonsils herniate through foramen

magnum• Sudden respiratory and cardiovascular collapse as

medulla impinges; • Ppinpoint pupils and flacid quadripelegia

• Upward Transtentorial• Expanding posterior fossa lesion• ALOC, pinpoint pupils, downward conjugate gaze

with absence of vertical eye movement

TBI: Herniation Syndromes

pCO2 leads to cerebral vasoconstriction CBF:

cerebral volume ICP

– Indication:• Herniation• Acute neurological deterioration• Refractory elevated ICP

– Risks:• Cerebral ischemia• Respiratory alkalosis

ICP Management: CO2

• Mannitol Blood viscosity

• First mechanism• Rapid onset but lasts <75min

– Osmotic effect• Slow onset 13-30min, duration~6hrs • Normal BBB is required.

– Goal = euvolemic hyperosmolar state• Bolus doses (0.25-1g/kg)• Serum osmolarity <320mOsm/L

– Risks:• ATN, RF, hypovolemia

ICP Management: Hyperosmolar Rx

• Hypertonic Saline (3%)– Osmotic effect– Other effects:

• Restoration of normal resting membrane potential and cell volume

• Stimulation of ANP release (cardiac output)

– Risks• rebound ICP, lyte abN (CPM), SAH

ICP Management: Hyperosmolar Rx

• Hypertonic Saline (3%)– Limited clinical experience, good

results ICP, CPP, shorter PICU stay (II)

– Bolus dosing:• 2-4cc/kg

– Infusion 0.1-1mL/kg/hr• Can titrate to ICP<20mmHg• Osmolarity <360mOsm/L

ICP Management: Hyperosmolar Rx

• Steroids– Not recommended– No improvement in outcome or ICP(II)

• Refractory ICP– CSF drainage– Sedation/Paralysis– High dose barbituates(monitoring,BP

support)– Hypothermia– Decompressive craniectomy

• ICP monitoring

ICP Management:

• Primary and secondary insults result in poor outcomes– Strategies to avoid hypoxia,

hypo/hypertension, increased ICP should be considered.

• RSI:– Poor evidence for use of lidocaine but

standard of care– Caution with induction agents

Conclusion:

• Strategies for refractory ICP/herniation:– Hyperventilation– Hyperosmolar therapy– ICP monitoring/EVD/craniectomy– Barbituates– +/- cooling

– Avoid steriods

Conclusion: