Case
A 4-year-old, neutered male Labrador retriever is presented after being hit by a car. He is laterally recumbent and appears to be nonresponsive. Initial diagnostics reveal a packed-cell volume (PCV) of 27% (reference interval, 35%-57%), total solids of 6 g/dL (reference interval, 5.4-7.5 g/dL), blood glucose concentration of 165 mg/dL (reference interval, 76-119 mg/dL), and semiquantitative BUN (measured by reagent test strip) of 35 to 50 mg/dL (reference interval, 8-28 mg/dL).1,2 Heart rate is 60 bpm (reference interval, 70-120 bpm), systolic blood pressure is 190 mm Hg (normotensive, <140 mm Hg) on Doppler ultrasound, and respiratory rate is 30 breaths per minute (reference interval, 18-34 breaths per minute).3-5
On physical examination, the dog is nonresponsive to visual and auditory stimuli but responds (ie, vocalizes, tries to lift head) when hemostats are applied across the digits. The flexor reflexes are intact when hemostats are applied across the digits of both thoracic and pelvic limbs. The pupils are miotic and do not dilate substantially when the eyelids are closed. The oculocephalic reflex (which evaluates ocular movement when the head is rotated left to right) is present but subjectively reduced. There is an obvious closed left femoral fracture. Supplemental oxygen is provided via oxygen mask placed over the muzzle.
The patient has a modified Glasgow coma scale (MGCS) score of 10, indicating elevated intracranial pressure (ICP), which is supported by the presence of the Cushing reflex (ie, low heart rate despite high blood pressure).6,7 Hyperglycemia in this patient correlates with severity of traumatic brain injury (TBI) but has not yet been associated with outcome.8 PCV and total solids indicate a degree of volume loss, but blood pressure and heart rate values do not support hypovolemic shock or decompensated hypovolemic shock.
Quiz
Case Conclusion
For this patient, initial treatment with hypertonic saline and crystalloids would allow for reduction in ICP, improvement in cerebral perfusion pressure, and restoration of euvolemia. A fentanyl CRI would be appropriate, and administration of levetiracetam could also be considered for neuroprotective effects.
CT and/or MRI is useful in patients with head trauma to evaluate for surgical lesions (eg, compressive hematoma, depressed skull fracture) and is correlated with prognosis. MRI changes, including midline shift and percentage of intraparenchymal damage, have been associated with worse long-term outcomes.25