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Head trauma in small animal practice
- 1. Head trauma in small animal practice Valérie Sauvé, DVM, DACVECC Fifth Avenue Veterinary Specialists September 2010
- 2. Traumatic Brain Injury • Pathophysiology • Patient evaluation • Diagnostic work-up • Therapeutic approach • Case example
- 3. Causes Most common • Vehicular trauma • Crush injury • High-rise or other falls • Trauma from animal / Human
- 4. Pathophysiology • Primary brain injury – Impact / mechanical damage – Immediate and limited • Secondary brain injury – Minutes to days after injury – Due to both systemic and intracranial causes
- 5. Primary brain injury • Parenchymal damage – Contusion, hematoma, laceration – Diffuse axonal injury • Vascular damage – Hemorrhage and vasogenic edema • Axial vs extraxial hematomas – 10% Mild TBI – >80% Severe TBI
- 6. Secondary brain injury • Neurotransmitters • Reactive oxygen species • Pro-inflammatory cytokines • Ischemia • ATP depletion • Intracellular Na / Ca • NO accumulation • Cerebral lactic acidosis Result in • Neuronal cell damage and cell death • Cerebral edema • ↑ ICP • Compromised BBB • Variation in cerebrovascular reactivity
- 7. Systemic contributions • Hypotension • Hypoxia • Hypo/hyperglycemia • Hypo/hypercapnea • Hyperthermia • Electrolytes imbalances • Acid-base imbalances ↓ CPP / CBF / oxygen delivery → Worsening brain injury
- 8. Monro-Kellie Doctrine • 3 compartments contained in a rigid vault: – Brain parenchyma – Blood – CSF • Intracranial compliance • Autoregulation is limited – ↑↑ ICP → ↓ cerebral perfusion → ischemia
- 9. Pressure Autoregulation Health • Systemic BP • Metabolic rate • Acid-base status TBI • Disruption of autoregulation • ↑dependency on BP • Linear relationship CPP = MAP – ICP >70mmHg 80mmHg <10mmHg
- 10. Cushing’s reflex • ↑↑ ICP – Severe and life-threatening • ↓CBF → ↑ CO2 – Vasomotor center of brain • Sympathetic response → vasoconstriction – ↑ MAP to ↑ CPP • Baroreceptors in aortic arch and carotid arteries – Reflex bradycardia High BP and low HR
- 11. Patient evaluation • History • Physical examination • Triage / ABC - 4 vital organ systems – CV, Respiratory, Neurological…. Urinary • Complete evaluation of the trauma patient – Thoracic radiographs, orthopedic injuries, etc • Blood gas, BG, PCV/TS, electrolytes • BP, HR, arrhythmia, breathing, SpO2, etc
- 12. Neurological assessment • Complete neurological examination • Modified Glasgow coma scale – Level of consciousness • Coma on presentation = guarded prognosis – Motor activity • Opistotonos, rigidity • If decerebrate = poor prognosis – Brainstem reflexes • PLR, pupil size • Herniation
- 13. Interpretation of pupil size / PLR Pupil size PLR Level of the lesion Prognosis Midposition WNL Good Bilateral miosis ↓ to none Variable Unilateral mydriasis ↓ to none Cranial nerve III Guarded to poor Unilateral mydriasis + ventrolateral strabismus ↓ to none Midbrain Guarded to poor Midposition None Pons / Medulla Poor to grave Bilateral mydriasis ↓ to none Poor to grave Adapted from Fletcher DJ and Syring RS in Small Animal Critical Care Medicine 2009
- 14. Advanced imaging CT / MRI • No response • Worsening • Moderate to severe signs on presentation • Lateralizing signs
- 16. Therapeutic approach • Treat concurrent injuries / stabilize – Hypovolemia, hypoxemia and hypoventilation • Maintain cerebral perfusion pressure CPP = MAP – ICP • ↓ ICP • Control cerebral metabolic rate
- 17. Fluids / Blood pressure • First priority to restore systemic perfusion • MAP is a primary determinant of CPP – MAP 80-100 mmHg or Doppler 100-120 mmHg • Small boluses repeated – Crystalloids 20 ml/kg Cn / 10-15 ml/kg Fe – Colloids 5 ml/kg Cn / 3 ml/kg Fe • Increased interest for hypertonic saline – Improves both systemic perfusion / BP and ↓ cerebral edema – 4 ml/kg over 5 minutes (7% NaCl)
- 18. Respiratory considerations • Prevent hypoxemia: > 90mmHg and CaO2 – Erratic respiratory pattern – Pulmonary traumatic lesions – Associated with outcome • O2 supplementation • Prevent coughing, struggling, hyperthermia, anxiety and sneezing
- 19. Respiratory considerations • Monitor CO2 : CBF and CBV – ↓ → vasoconstriction → ↓ CBF / ICP – ↑ → vasodilatation → ↑ ICP • Gag reflex and intubation • Consider mechanical ventilation – PaO2 < 60mmHg FIO2 60% – PaCO2 > 60 mmHg • Consider before in TBI – Apnea / WOB
- 20. Intern question ! Which of the following order is correct in a normal animal when comparing different ways to measure CO2? A) ETCO2 > PvCO2 > PaCO2 B) ETCO2 < PvCO2 < PaCO2 C) ETCO2 < PaCO2 < PvCO2 D) ETCO2 > PaCO2 > PvCO2
- 21. Answer! In a normal animal: C • PvCO2 > PaCO2 by 2-5 mmHg • ETCO2 < PaCO2 by 5 mmHg Target in TBI PaCO2 35-40 mmHg PvCO2 40-45 mmHg
- 22. Mannitol First line • After volume repletion • 0.5 – 1.5 G/kg • Filter • Over 15-20 minutes • May repeat • Monitor hydration / electrolytes Contraindications: • Hypovolemia • Hypernatremia • Dehydration Effects • ↓ICP, ↑CPP / CBF • ↑ Outcome • ↓ Blood viscosity • Osmotic shift • Diuresis • Free radical scavenger
- 23. Other hyperosmotics and diuretics Hypertonic saline • ↓ ICP and brain water content • ↑ CBF • ↓ brain excitotoxicity • Contraindicated if hyponatremic • Cardiac / pulmonary disease Furosemide • No longer recommended
- 24. Glycemia Hyperglycemia • Sympatho adrenal response • Potentiates brain injury – ↑ Free radicals, excitatory aa, cerebral edema and acidosis – Alters cerebral vasculature • Associated with severity of injury • Increased mortality / worse outcome (Hu/exp)
- 25. Corticosteroids • Contraindicated • Increased mortality in people • Cause iatrogenic hyperglycemia, immune suppression, delayed healing, gastrointestinal ulceration, worsens catabolic state…
- 26. Other drug therapy? Anticonvulsive • Prophylaxis ? • Diazepam • Phenobarbitol Barbiturates • Last resort for ↑ ICP?
- 27. Other supportive care • Pain – Opioids • Elevate head/neck 15-30 degrees • Avoid neck pressure / jugular occlusion • Body temperature – Hypothermia? – Avoid Hyperthermia • Turning / PROM / physical therapy • Nutrition • Stress ulcers – Famotidine / PPIs • Prokinetic • Bladder/colon care • Other injuries
- 28. Surgical intervention? • Rarely necessary or performed – Subdural hematoma – Depressed skull fractures – Expanding mass – Contaminated foreign body – Bite wounds • Decompressive craniotomy The Extraction of the Stone of Madness H. Bosch 1488-1516
- 29. I was rolled on… DSH, 3-4 months, Fem History • Unclear accident with a rocking chair, the owner is a little drunk • T 95F • P 140 bpm • R 26 bpm • Pale mm, CRT 3 sec • No femoral pulses palpable
- 30. Physical examination • Lateral recumbency, covered in dried blood, abnormal mentation, anisocoria, no menace, head tilt and turn, epistaxis, PLR + OU What will you do first? A) Mannitol B) Recommend euthanasia C) IV fluid bolus D) Blood transfusion E) Skull radiographs
- 31. Emergency Treatment • IVC / NOVA / PCV/TS / BP 50 mmHg • O2 mask • C) Delicate and progressive resuscitation – Small crystalloid boluses with reevaluation • 10 ml/kg x 2 over 15 min = BP 72 mmHg – NaCl 23.4 % + HES 6% (1:2) at 4 ml/kg • Mannitol 0.5 G/kg – Once the BP has improved 100 mmHg • Active rewarming – Baer Hugger
- 32. Continued Care • Butorphanol IV • Oxygen mask • Elevated head/neck • Famotidine IV • Fluids maintenance • Follow BP • Clean and look for wounds • Complete orthopedic exam • Thoracic radiographs • Turn q4hr • Recheck PCV/TS • Feed q4hrs kitten • Neurological status monitoring
- 33. Progression • BG: 278 mg/dL to 100 mg/dL • Improved neurological status within 1 hr • D/C O2 and BP monitoring the next day • No thoracic or orthopedic injury • Was bleeding from mouth and nose • Walking within 2 days. • Home in 3 days!
- 34. Prognosis • Do not get discouraged by appearance of patient on presentation • Small animal patients have great capacity to compensate for loss of brain function • Many pets will recover to be functional • Residual deficits • Complications
- 35. Conclusion • Very rewarding to treat ! • Treat early and aggressively!
- 36. Therapeutic summary • Oxygen supplementation • Normotension • Normoglycemia • Maintain low normal CO2 • Elevate head/neck 15-30 degrees • Supportive care and other injuries • Mannitol or Hypertonic NaCl; NO steroids • Avoid jugular compression, sneeze/cough
- 37. Questions
Notes de l'éditeur
- Subdural, subarachnoid or epidural
- Progression rather than firm prognosis Transtentorial herniation pressure on 3 rd cranial nerve and pupil dilation from decreased parasympathetic inevation to eye cause bilateral mydriasis