Moderate and severe traumatic brain injury: SAQ

This boy has severe traumatic brain injury with signs of impending herniation. A Glasgow Coma Scale of 7 after resuscitation places him in the severe band, and the unilateral fixed dilated pupil is uncal herniation compressing the third nerve. His hypotension and his borderline oxygen saturation are secondary brain insults that will double his mortality if not corrected at once, so resuscitation and the lowering of the intracranial pressure must run together. [4]

Question 1 (10 marks)

Outline the immediate emergency department management of this child over the first ten minutes, justifying each step. [4]

A full-mark answer addresses the structured primary survey, the airway decision, the prevention of secondary brain injury, and the herniation response, each with the correct number or dose. [4]

Airway and breathing (3 marks). The boy has a GCS of 7, which is 8 or less, so the airway must be secured by rapid sequence intubation, because he cannot protect his airway and his oxygen saturation is already low. The cervical spine is immobilised throughout, because a significant head injury is presumed to carry a cervical spine injury until cleared. After intubation he is ventilated to a PaCO2 of 35 to 40 mmHg, keeping the normocapnia that avoids both the cerebral vessel constriction of hypocapnia and the vessel dilation of hypercapnia. Prophylactic hyperventilation is not used. [4]

Circulation and the prevention of hypotension (2 marks). The systolic blood pressure of 75 mmHg is hypotension for a 6-year-old, and a single hypotensive episode doubles the mortality, so it is treated at once with isotonic fluid boluses of 10 mL per kg of normal saline and blood if the response is poor. The cause of the hypotension, including an associated injury, is sought and treated. The glucose is normal, which is reassuring. [6]

The herniation response (3 marks). The unilateral fixed dilated pupil is uncal herniation, and the pressure must be lowered at once while the neurosurgical team is called. The head is elevated to 30 degrees and kept midline, and a hyperosmolar bolus of 3 percent saline 2 to 5 mL per kg, which is 44 to 110 mL for this 22 kg child, is given to lower the intracranial pressure. A brief period of hyperventilation is justified here as a temporary measure for the acutely herniating child while the definitive therapy is prepared. An urgent computed tomography of the head is arranged once the airway and circulation are stable, with neurosurgery alerted in parallel. [4]

Disposition and monitoring (2 marks). The boy is admitted to the paediatric intensive care unit, an intracranial pressure monitor is placed, and the pressure is treated above 20 mmHg while the cerebral perfusion pressure is kept at least 40 mmHg. Prophylactic anticonvulsants such as levetiracetam are given to prevent early post-traumatic seizures, and the temperature is kept normal, because prophylactic hypothermia is not recommended. [4][7]

Question 2 (10 marks)

Describe the stepwise intracranial pressure management ladder you would use in the paediatric intensive care unit, and critically appraise the role of hypothermia and decompressive craniectomy using the trial evidence. [4]

A full-mark answer reproduces the ladder with the correct thresholds and doses, and appraises the two trials by their conclusion and what they changed. [4]

The thresholds and the bedside measures (3 marks). The Brain Trauma Foundation pediatric guidelines set the intracranial pressure treatment threshold at 20 mmHg and the cerebral perfusion pressure floor at 40 mmHg, and the cerebral perfusion pressure equals the mean arterial pressure minus the intracranial pressure. The ladder begins with the head elevated to 30 degrees and kept midline, sedation and analgesia to reduce the metabolic demand, and a neuromuscular blocker if the child fights the ventilator. Cerebrospinal fluid is drained through an external ventricular drain. [4]

Hyperosmolar therapy (3 marks). The next step is a 3 percent saline bolus of 2 to 5 mL per kg, titrated to the pressure and the serum sodium up to 155 mmol per litre, or mannitol 0.25 to 1 g per kg, given with attention to the circulating volume because the diuresis can drop the blood pressure. The therapy is titrated to an intracranial pressure below 20 mmHg, and the serum sodium and osmolality are checked frequently. [4]

The refractory options (2 marks). A barbiturate coma, with pentobarbital or thiopentone titrated to burst suppression on the electroencephalogram, is used for the refractory case. Decompressive craniectomy is the last-resort surgical option for the genuinely refractory case. [5]

Trial appraisal (2 marks). The Hutchison trial of 2008 showed that prophylactic hypothermia did not improve outcome and raised concern about harm, so the child is kept normothermic and hypothermia is not used as a treatment. The DECRA trial of Cooper and colleagues in 2011 showed that an early bifrontal decompressive craniectomy for refractory pressure was associated with worse outcomes, so the craniectomy is reserved for the refractory case that has failed the medical ladder rather than used early. Both trials reshaped the refractory end of the ladder by showing that an aggressive intervention can do harm. [7][8]