Moderate and severe traumatic brain injury: Viva

Branch 1: Severity grading and the meaning of the hypotension

The candidate should grade the injury as severe using the Glasgow Coma Scale. A strong candidate states that the scale scores eye opening from 1 to 4, verbal response from 1 to 5, and motor response from 1 to 6, that the total of 6 places the child in the severe band of 3 to 8, and that the line that matters is at 8, because a child at or below 8 cannot protect the airway and is at high risk of raised intracranial pressure. The candidate should add that the verbal component is modified for the preverbal child, with the score of 5 for coos and babbles down to 1 for no response, as reviewed by Kirkham. ^[1][2]

If the examiner presses on the hypotension, the candidate should explain that a single hypotensive episode doubles the mortality in severe paediatric traumatic brain injury, because the falling mean arterial pressure collapses the cerebral perfusion pressure. The candidate should link this to the equation that cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure, and state that the blood pressure is therefore defended from the first contact with isotonic fluid and blood. ^[4]