Triaging Traumatic Brain Injuries
Patients presenting with head injuries are a common occurrence in an emergency practice. Efficient triage is essential in initiating treatment early. As with any emergency, the quicker treatment is instituted, the better the chances for a positive outcome.
Traumatic brain injuries are commonly caused by vehicular trauma, falls, or dog attacks. The initial injury is classified as a primary brain injury, a direct insult or damage to the brain tissue and/or brain vasculature. A secondary brain injury is defined as further damage to the brain tissue from inflammation, hypoxia, or decreased cerebral perfusion that occurs as a sequelae to primary brain injury.
Related Article: How to Normalize Emergencies in Practice
Primary Survey
When a patient presents with suspected or known head injuries, basic triage, known as the primary assessment, should be performed. Airway, breathing, and circulation must be assessed to determine whether life-saving procedures such as cardiopulmonary resuscitation should be initiated. Next, an intravenous catheter should be placed and a minimum database developed, including:
Temperature, pulse, and respiration
Mucous membrane color
Capillary refill time
Blood pressure
Electrocardiogram
PCV/TS (packed cell volume/total solids)
Blood glucose
Lactate.
It is important to avoid catheter placement and blood sampling from the jugular vein in patients with suspected head trauma because pressure and occlusion of the vein subsequently causes increased intracranial pressure.
The minimum database is essential for a global picture of the patient’s status and will help determine treatment. Treating coexisting problems such as shock and hypoxia is especially important as hypovolemia and hypoxia directly impede cerebral perfusion and may result in a deterioration of mentation. Treatment goals are to restore perfusion by correcting volume needs with crystalloid fluids and avoid hypotension. Oxygen supplementation is imperative during stabilization to assist in maximum tissue oxygenation and should be provided by either flow-by technique or directly via intubation. Patients in severe respiratory distress, or those with abnormal breathing patterns such as apnea or Cheyne-Stokes breathing patterns (periodic hyperpnea that alternates with apnea), may need intubation to provide adequate oxygenation and ventilation. Use of nasal cannulas, which can increase intracranial pressure, should be avoided. Temperature should be maintained at low normal (99°F–100°F [37.2°C – 37.8°C]) to prevent or reduce cerebral edema.
Neurologic Examination
The Modified Glasgow Coma Scale (MGCS) is a systematic approach to the neurologic examination and should be performed early in admission (see Table). The MGCS is helpful in determining the severity of brain damage, proper course of therapy, future prognosis, and efficacy of therapy.1 Serial MGCS scores should be performed every 1–4 hours, depending on severity of the injury, to track patient progress or deterioration. Since it relies on caretakers’ subjectivity less than traditional mentation evaluation, the MGCS score is helpful in monitoring trends across shift changes.
During the entire examination, use caution when manipulating the patient’s head and neck; skull and cervical vertebral fractures commonly occur with head trauma and can worsen with additional handling.
The MGCS first step is determining the patient’s level of consciousness (LOC), which refers to the patient’s level of alertness and responsiveness to visual, auditory, and noxious stimuli. With cerebral edema and increasing intracranial pressure, LOC may change quickly. Other factors, such as hypovolemia, hypoxia, hypothermia, and medication administration (ie, opioids), can also impact LOC.
Next, assess brain stem reflexes, including pupil size and symmetry, pupillary light reflex (PLR), and palpebral reflex. Certain medications can interfere with this portion of the examination as well (eg, atropine). Bilaterally dilated pupils (mydriasis) with no PLR carry a grave prognosis and indicate severe brain damage.
Posture and motor activity can be challenging to assess depending on LOC. There are 2 particular postures to note, both which can be seen with severe brain damage2:
Decerebrate rigidity, which is seen in an unconscious patient that, when stimulated, has extensor rigidity of all 4 limbs with dorsoflexion of the neck and head
Decerebellate rigidity, which is seen in a patient that can be aroused, and includes opisthotonus (arching of the spine), extensions of the forelimbs, and flexion of the rear limbs.
Respiratory rate and pattern are important monitoring parameters. Patients with brain stem damage often have compromised ventilation capabilities and subsequent oxygenation derangements. Two common patterns seen with brain damage are Cheyne-Stokes pattern and apneustic breathing (irregular respiratory pattern with periods of apnea.) Abnormal respiratory patterns that affect oxygenation, ventilation, and temperature indicate a need for mechanical ventilation until the cerebral edema resolves.2
Cushing’s Reflex
During stabilization and the neurologic examination, be aware of signs indicating deteriorating mental status. Decreased cerebral perfusion causes an increase in both cerebral ischemia and carbon dioxide. Cardiac output is then increased to compensate for the decrease in cerebral blood flow decrease and catecholamines are released, causing systemic vasoconstriction. Baroreceptors sense this change in blood pressure and signal a drop in heart rate. This bradycardia, and the accompanying simultaneous hypertension, make up the Cushing’s reflex.3 This occurs immediately preceding herniation of the cerebellum due to increased intracranial pressure from cerebral edema. Immediate intervention with either mannitol (an osmotic diuretic) or hypertonic saline (which increases intravascular osmotic pressure) is necessary in this situation.
Additional Considerations
Several other considerations should be kept in mind during triage of the head trauma patient. Pain, vomiting, seizures, coughing, downward head position, and occlusion of the vessels in the neck can all contribute to increased intracranial pressure. Care should be taken to ensure the patient’s head and chest is kept at a 30° angle. Analgesics should be administered as soon as possible. Seizures can occur and should be treated immediately with an appropriate anticonvulsant. Vomiting, retching, and/or gagging should also prevented using central-acting antiemetics, particularly if the patient exhibits signs of nausea.2
Outcomes
Prognosis and outcomes of head trauma vary widely. However, with knowledge of proper, efficient triage, the veterinary professional can initiate treatment quickly to help ensure the best possible outcome.