Page 845 - Cote clinical veterinary advisor dogs and cats 4th

Head Trauma 405

HISTORY, CHIEF COMPLAINT • Animals with hypotensive shock may to tissues). A global approach to diagnosis and
• History of traumatic event manifest altered consciousness without treatment is outlined on p. 1421.
VetBooks.ir inappropriate behavior, or seizure activity. assessment after initial stabilization has been Acute General Treatment Diseases and Disorders
neurologic damage. Repeat full neurologic
• Owners may report loss of consciousness,
Maintain mean arterial BP > 60 mm Hg
completed.
PHYSICAL EXAM FINDINGS
disease) may also affect neurologic exam and
Hg): manage by titration of intravenous fluids.
• Signs of hypovolemic shock (e.g., tachycardia, • Metabolic diseases (e.g., hypoglycemia, liver (generally signifies that systolic BP > 90 mm
hypotension, pale mucous membranes [p. should be considered as differentials if no Options:
911]) may be present. traumatic event is reported or if the history • Isotonic crystalloids: (10-20 mL/kg IV) exact
• Neurologic exam (p. 1136); indicators of is uncertain. dose is titrated to BP; do not over-resuscitate
intracranial injury: ○ Avoid fluids with excessive free water
○ Anisocoria, abnormal pupil reactivity Initial Database (maintenance fluids, 5% dextrose in water,
(excluding ocular trauma): dilated, Baseline tests (packed cell volume/total solids 0.45% saline).
unresponsive pupils (in the absence of [PCV/TP], blood glucose, blood urea nitrogen); • Hypertonic saline (7.5%) 2-4 mL/kg IV
ocular trauma or atropine) indicate severe initial assessment of some metabolic causes of slowly; provides rapid volume expansion
neurologic injury and a poor prognosis. altered mentation: ○ Decreases ICP as effectively as mannitol
○ Diminished or absent oculocephalic (doll’s • Consider transfusion if necessary (p. 1169) • Colloids (e.g., hetastarch, pentastarch 5 mL/
eye) reflex to support oxygen delivery to tissues. kg IV bolus, maximum of 20-40 mL/kg/
○ Postural reaction deficits (may be due to • Avoid hyperglycemia. day, depending on product). Oncotic effect
spinal injury [p. 930]: note remainder of • If azotemia or dehydration is present, diuret- draws free water into the vasculature and
neurologic findings) ics should be used with caution if at all; provides intravascular volume with limited
○ Diminished or altered consciousness maintaining normotension is paramount. fluid administration volumes.
(may be due to shock; note remainder Blood pressure (p. 1065): Decrease intracranial pressure:
of physical exam) • Identify and correct systemic hypotension. • Mannitol 0.5-1 g/kg IV q 6-8h; limit to
• Skull fractures may be palpable. • Systemic hypertension may be a result of three bolus injections/24-hour period.
• Respiratory, musculoskeletal, and other body elevated ICP or a consequence of pain or Osmotic diuretic with free radical–scavenging
systems may show signs of traumatic injury. anxiety. properties decreases blood viscosity, increases
○ Hemorrhage may be visible in ear canal, Blood gas or pulse oximetry: cerebral blood flow.
eyes (episcleral or hyphema), or epistaxis. • Identify hypoxemia (e.g., PaO 2 < 80 mm ○ Diuresis may decrease blood volume and
Hg, SpO 2 < 95% when breathing room air), BP (ensure adequate BP and volume status
Etiology and Pathophysiology and provide supplemental oxygen p. 1146. before administration).
• Cerebral blood flow (CBF) is mainly • Identify and correct hypoventilation (PaCO 2 ○ May result in reverse osmotic shift. In areas
determined by blood pressure (BP). Auto- > 50 mm Hg). of hemorrhage, mannitol may leak into
regulation maintains blood flow to the brain Heart rate/electrocardiogram (p. 1096): interstitium, worsening cerebral edema.
over a range of blood pressures (60-160 mm • Sinus tachycardia common with hypovolemia The effects of mannitol on lowering ICP
Hg) but is lost when systolic arterial BP < or pain; ventricular arrhythmias possible may outweigh these potential effects on
50 mm Hg or after brain injury (at which (p. 1033) damaged areas.
time arterial BP is directly correlated to blood • Bradycardia may be seen with elevated ICP; ○ May be combined with furosemide 2 mg/
flow to the brain). a rapid onset of bradycardia with hyperten- kg in emergency situations or when needed
• Cerebral perfusion pressure (CPP = mean sion (Cushing’s response) portends brain for other therapy (e.g., pulmonary edema)
arterial pressure [MAP] − intracranial herniation. • Hypertonic saline (7%) 2-4 mL/kg IV:
pressure [ICP]) is used for estimating CBF. hypertonic crystalloid fluid with antiin-
As ICP rises or MAP decreases, cerebral Advanced or Confirmatory Testing flammatory and free radical–scavenging
perfusion decreases. • Radiographs properties.
• Trauma can result in primary (at the time ○ May be useful in identifying skull fractures ○ ICP lowering drug of choice in hypoten-
of incident due to direct neuronal damage ○ Of limited value in the overall assessment sive patients (does not result in diuresis)
and hemorrhage) or secondary (hours or days of intracranial injury ○ May be combined with colloid for volume
after the incident due to energy depletion, • CT expansion effects
free radical generation, cytokine release) ○ Comatose/obtunded patients may be Maintain adequate oxygenation:
injury to the brain. Treatment aims to imaged without anesthesia. • Supplemental oxygen as needed (p. 1146)
prevent or limit secondary injury. ○ Evaluate for skull fractures, hemorrhage, ○ Sneezing increases ICP, and oxygen cages
or other injuries. are preferable to nasal cannulas, if available.
DIAGNOSIS • MRI (p. 1132) • Ensure adequate oxygen-carrying capacity
○ May be helpful in detecting subtle lesions (hematocrit/hemoglobin) and delivery
Diagnostic Overview and provide prognostic guidance (adequate cardiac output).
Diagnosis is based on a history of trauma with • ICP monitoring • Elevate head by placing patient on a ramp
physical signs of intracranial injury. Complete ○ Useful for directing therapies; may have raised 15°-25° from the ground, which
neurologic evaluation is essential for establishing prognostic significance promotes venous drainage from the cerebrum
the treatment plan and prognosis. Concur- ○ Infrequently used in veterinary medicine; and may help to decrease ICP.
rent injuries affecting other body systems are requires specific skills and advanced care • Kinks in the neck can obstruct jugular venous
common and should be evaluated as part of drainage from the brain, and use of a ramp
the diagnostic plan. TREATMENT is important.
Miscellaneous therapies:
Differential Diagnosis Treatment Overview • Surgery
• Rule out other causes of intracranial disease Treatment is aimed at ensuring adequate cere- ○ Craniotomy: removal of hematomas,
(e.g., neoplasia, infectious, inflammatory, bral perfusion and decreasing ICP. Important control of hemorrhage with depressed skull
congenital), especially when trauma is not goals include maintaining adequate systemic fractures, or for removal of penetrating
witnessed. BP and systemic oxygenation (oxygen delivery objects

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