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Pediatric TBI

Pediatric TBI . Heather Patterson PGY -3 April 29 2008. TBI: Objectives . Classification of TBI Primary and secondary injuries Definitions Physiology Airway management When to intubate Premedication Management of increased ICP and neuroprotective strategies. TBI: Classification.

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Pediatric TBI

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  1. Pediatric TBI Heather Patterson PGY -3 April 29 2008

  2. TBI: Objectives • Classification of TBI • Primary and secondary injuries • Definitions • Physiology • Airway management • When to intubate • Premedication • Management of increased ICP and neuroprotective strategies

  3. TBI: Classification

  4. TBI: Classification • Mild • GCS 13-15 • Moderate • GCS 9-12 • Severe • GCS <9

  5. 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

  6. 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***

  7. TBI: Secondary injury • We know these are bad… • Hypotension • Hypertension • Hypoxia • Seizures • Anemia • How bad are they?

  8. TBI: Secondary injury - ↑ICP • 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

  9. TBI: Secondary injury -hypotension • 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 Chestnut et al. J Neurosurg 1990

  10. TBI: Physiology • 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

  11. Monro-Kellie Doctrine Brain + blood + CSF + mass = constant volume ICP maintained at constant level …… to a point TBI: Autoregulation Cerebral Autoregulation

  12. TBI: Physiology • 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

  13. CPP = MAP – ICP High ICP = bad Low MAP = bad TBI: Autoregulation Cerebral Autoregulation

  14. TBI: Pediatric Physiology • 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. Uptodate.

  15. Case: • 8yo male • ATV, no helmet, rolled, hit head on rocky ground • GCS 9 on EMS arrival • Became more alert during transport

  16. 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?

  17. Resuscitation: Airway/Breathing • What are the indications for intubation in this patient? • What drugs would you like to use? • What about his neck?

  18. C-Spine • 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

  19. Indications for Intubation: • Inability to maintain or protect the airway • Inadequate ventilation or oxygenation • Hemodynamic instability • Projected clinical course • Excessive combativeness

  20. Response to intubation: HR & BP • 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

  21. Response to intubation: ICP • Laryngoscopy & Intubation Increase ICP • Valsalva & cough reflex • Well described to increase ICP • 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 • Increased HR and BP = pressor response - increased CBF

  22. Physiologic Goals of Intubation: • Avoid Hypotension • Cerebral Ischemia • Increases mortality • Avoid Hypertension • Cerebral edema • Increased capillary hydrostatic pressure • Increases ICP • increased cerebral blood volume • Increases hemorrhage and hematoma

  23. Physiologic Goals of Intubation: 3. Avoid Hypoxia: - Cerebral ischemia

  24. Premedication: • Ideal meds: • Don’t cause hypertension and tachycardia • Don’t cause hypotension • Don’t increase ICP

  25. Premedication: Opioids Opioids

  26. Premedication: Opioids • Attenuates pressor response (↑HR/BP) • Higher doses cause hypotension • No evidence about effect on ICP during intubation • No evidence about neurological outcomes

  27. Premedication: Opioids • RCT N=60 • Saline • lidocaine 2/kg • Alfentail 15/kg • Alfentanil 30/kg • Looked at HR, BP

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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%)

  33. Premedication: Opioids • No study on opioids and ICP during intubation • ICU studies showing • Increased ICP • Decreased ICP • Variable effects on MAP

  34. Premedication: Opioids • Attenuates pressor response (↑HR/BP) • Higher doses cause hypotension • No evidence about effect on ICP during intubation • No evidence about neurological outcomes

  35. Premedication: Lidocaine Lidocaine

  36. 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 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

  37. Premedication: Lidocaine 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 Kuzak et al 2006 CJEM

  38. Premedication: Lidocaine 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. • 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)

  39. Premedication: Lidocaine 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) • 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

  40. 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)

  41. 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

  42. 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

  43. 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

  44. ΔICP Lidocaine +4 (+/-2) mmHg (no different than saline) Succinylcholine + Fentanyl Significantly attenuated ICP rise MAP & CPP No differences among groups Premedication: Lidocaine

  45. 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)

  46. 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

  47. Premedication: Defasciculation • 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

  48. Induction Agents: • Thiopentol 3-5mg/kg • Etomidate 0.3mg/kg • Not often used in children • Ketamine currently not used for head injury.

  49. Resuscitation: Airway/Breathing • 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

  50. Resuscitation: Circulation • 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 watercerebral edema) • PRBC –need to maintain O2 delivery • Secondary injuries blood loss

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