Head Trauma Flashcards
What is the make-up of brain fluid?
- Brain matter 80%
o Functions: maintain life, senses - Blood 10%
o Functions: Provide glucose and oxygen, removes metabolic waste products - Cerebrospinal Fluid (CSF) 10%
o This is a water solution that is similar in composition to blood plasma
o Functions: Liquid cushion that gives buoyancy to CNS organs, it also protects the CNS from trauma.
What is the skulls layer of protection?
- Skull o Extradural Space Consists mainly of blood vessels, these are mainly arterial o Dura Mater Outmost strong connective tissue o Subdural Space Consists of blood vessels, these are mainly venous - Arachnoid Mater o Subarachnoid Space Contains CSF and large blood vessels - Pia Mater o Delicate connective tissue that clings tightly to the brain - Brain tissue
What is each respective hemisphere of the brain responsible for?
- Right
o Visual-spatial skills, emotion and artistic skills - Left
o Language, math and logic
What is the Cerebellum responsible for?
- Involuntary movement, posture, balance, coordination and speech
What functions is the brain stem responsible for?
- It is the gatekeeper of messages from the PNS to the CNS
- Basic life-sustaining functions, breathing, swallowing, respirations and heart rate
What % of the bodies cardiac output and 02% does the brain consume?
- 15% of the total cardiac output and 20% of the bodies 02%
What is the brain so susceptible to bleeds, especially in trauma settings?
- Because the brain itself along with all its tissues and protective layers are very well perfused, this leads it very prone to bleeds, especially after trauma.
What does Mean Arterial pressure (MAP) recognise?
- That tissue perfusion is influenced by both DBP and SBP
How do you calculate MAP?
MAP = (SBP + (2xDBP)) /3
Why is brain perfusion important and how is it maintained?
- Because the brain require cerebral blood flow to supply it with glucose and oxygen.
- It is maintained through a certain pressure gradient known as cerebral perfusion Pressure CPP.
What is the main driver of CPP and what is the main antagonist of CPP?
- The main driver of an adequate CPP is an adequate MAP.
- ICP works against the CPP to impede CBF flow.
How do you calculate CPP, what is a normal ICP and CPP? - CPP = MAP – ICP
- Normal range for ICP is 0 – 15mmHg
- Normal range of CPP is >60mmHg
- Normal MAP 70-110mmHg
If auto regulation is lost in the setting of severe head trauma what is the brain at increased risk of? - Loss of CBF which may lead to ischemia = neuronal death = irreversible injury
What is a compensation mechanism that occurs after bleeding to help maintain ICP in trauma?
- CSF is redistributed, once this occurs ICP quickly rises. Once ICP rises past its normal range of 0-15mmHg to >20mmHg (intracranial hypertension occurs).
What are the three stages of intracranial hypertension?
- Stage 1
o PT may present if transient confusion and drowsiness - Stage 2
o Hypertension and systemic vasoconstriction will occur to alleviate neuronal ischemia.
o Compromised neuronal oxygenation (hypoxia), will results in neurological symptoms - Stage 3
o Cheyne-stoke respirations (an abnormal pattern of breathing, may be deeper and faster breathing followed by a gradual temporary apnoea.
o Pupils are sluggish and dilated
o Increased PP
o Bradycardia
o Bradyponoea
What does an Increase in ICP lead to, and what are common causes of ICP?
- An increase in ICP leads to a decrease in CBF which leads to neuronal hypoxia and further brain injury.
- Common causes of increased ICP are, bleeding, masses (tumor), vomit, gag and sneezing. Head trauma patients are more liable to an increase ICP due to the loss of cerebral auto regulation.
What are signs of severely increased ICP?
- Cushing’s Triad
o Systolic hypertension
o Bradycardia
o Irregular respiration