pediatric tbi heather patterson pgy -3 april 29 2008
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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:
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