Episode 30: Head injury


Quite a few of our previous podcasts include content which is relevant to this Head Injury one. Why not go back and have a listen to:

Episode 3: Hyperoxia

Episode 20: End Tidal Carbon Dioxide

Episode 28: LOST (Low Output State in Trauma)

Munroe-Kellie Doctrine

The Munroe-Kellie Doctrine is illustrated by the following pictures:

Monroe Kellie doctrine diagram

Or, alternatively, by Elfyn’s pint of Guinness analogy!


Allows giraffes to drink from pools without a rush of blood to the head and eat leaves from trees without fainting.

This graph shows what happens to cerebral arterioles in uninjured brains, taken from Researchgate.net (Pires et al., 2013.)


Without autoregulation, in an injured brain, the arterioles will not change diameter in response to variations in blood pressure, and cerebral blood flow will have a linear relationship with blood pressure.

Cerebral perfusion pressure

Cerebral perfusion pressure = Mean arterial pressure – intracerebral pressure

The diameter of the arterioles, and therefore Cerebral perfusion pressure, is also affected by extremes of oxygen and carbon dioxide. If you would like to read more about this, have a look at this Life in The Fast Lane post.


The Brain Injury Foundation guidelines which Fliss mentions can be accessed here.

Doubts over head injury studies. Roberts I, Smith R, Evans S. BMJ. 2007 Feb 24; 334(7590): 392–394. (This is the paper Elfyn mentions regarding the now redacted original publications on the use of mannitol)

Wakai A, McCabe A, Roberts I, Schierhout G. Mannitol for acute traumatic brain injury. Cochrane Database of Systematic Reviews 2013, Issue 8. Art. No.: CD001049. DOI: 10.1002/14651858.CD001049.pub5

The HIRT trial: https://emj.bmj.com/content/32/11/869

The HITS-NS trial: The Head Injury Transportation Straight to Neurosurgery (HITS-NS) randomised trial: a feasibility study.

Wilson et al. Prognosis of patients with bilateral fixed dilated pupils secondary to traumatic extradural or subdural haematoma who undergo surgery: a systematic review and meta-analysis. 

Impact Brain Apnoea. https://www.ncbi.nlm.nih.gov/pubmed/27211834

And finally…

…. if you would like to hear more on the subject of Head Injury – have a listen to what the Resus Room team have to say about it:

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