Head trauma in small animal practice
-
Upload
vsauve -
Category
Health & Medicine
-
view
456 -
download
1
Transcript of Head trauma in small animal practice
Head trauma in small animal practice
Valérie Sauvé, DVM, DACVECCFifth Avenue Veterinary Specialists
September 2010
Traumatic Brain Injury
• Pathophysiology
• Patient evaluation
• Diagnostic work-up
• Therapeutic approach• Case example
Causes
Most common • Vehicular trauma • Crush injury
• High-rise or other falls• Trauma from animal / Human
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
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
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
Systemic contributions
• Hypotension • Hypoxia• Hypo/hyperglycemia • Hypo/hypercapnea
• Hyperthermia • Electrolytes
imbalances • Acid-base imbalances
↓ CPP / CBF / oxygen delivery → Worsening brain injury
Monro-Kellie Doctrine
• 3 compartments contained in a rigid vault: – Brain parenchyma– Blood– CSF
• Intracranial compliance
• Autoregulation is limited – ↑↑ ICP → ↓ cerebral perfusion → ischemia
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
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
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
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
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
Advanced imaging
CT / MRI
• No response • Worsening
• Moderate to severe signs on presentation
• Lateralizing signs
Cat brain imaging
Therapeutic approach
• Treat concurrent injuries / stabilize – Hypovolemia, hypoxemia and hypoventilation
• Maintain cerebral perfusion pressure CPP = MAP – ICP
• ↓ ICP • Control cerebral metabolic
rate
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)
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
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
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
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
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
Other hyperosmotics and diuretics
Hypertonic saline • ↓ ICP and brain water content• ↑ CBF• ↓ brain excitotoxicity • Contraindicated if hyponatremic• Cardiac / pulmonary disease
Furosemide • No longer recommended
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)
Corticosteroids
• Contraindicated
• Increased mortality in people
• Cause iatrogenic hyperglycemia, immune suppression, delayed healing, gastrointestinal ulceration, worsens catabolic state…
Other drug therapy?
Anticonvulsive• Prophylaxis ?
• Diazepam • Phenobarbitol
Barbiturates
• Last resort for ↑ ICP?
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
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
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
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) MannitolB) Recommend euthanasia C) IV fluid bolusD) Blood transfusion E) Skull radiographs
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
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
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!
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
Conclusion
• Very rewarding to treat !
• Treat early and aggressively!
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
Questions