Head Trauma Flashcards
1
Q
What is the make-up of brain fluid?
A
- 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.
2
Q
What is the skulls layer of protection?
A
- 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
3
Q
What is each respective hemisphere of the brain responsible for?
A
- Right
o Visual-spatial skills, emotion and artistic skills - Left
o Language, math and logic
4
Q
What is the Cerebellum responsible for?
A
- Involuntary movement, posture, balance, coordination and speech
5
Q
What functions is the brain stem responsible for?
A
- It is the gatekeeper of messages from the PNS to the CNS
- Basic life-sustaining functions, breathing, swallowing, respirations and heart rate
6
Q
What % of the bodies cardiac output and 02% does the brain consume?
A
- 15% of the total cardiac output and 20% of the bodies 02%
7
Q
What is the brain so susceptible to bleeds, especially in trauma settings?
A
- 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.
8
Q
What does Mean Arterial pressure (MAP) recognise?
A
- That tissue perfusion is influenced by both DBP and SBP
9
Q
How do you calculate MAP?
A
MAP = (SBP + (2xDBP)) /3
10
Q
Why is brain perfusion important and how is it maintained?
A
- 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.
11
Q
What is the main driver of CPP and what is the main antagonist of CPP?
A
- 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
12
Q
What is a compensation mechanism that occurs after bleeding to help maintain ICP in trauma?
A
- CSF is redistributed, once this occurs ICP quickly rises. Once ICP rises past its normal range of 0-15mmHg to >20mmHg (intracranial hypertension occurs).
13
Q
What are the three stages of intracranial hypertension?
A
- 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
14
Q
What does an Increase in ICP lead to, and what are common causes of ICP?
A
- 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.
15
Q
What are signs of severely increased ICP?
A
- Cushing’s Triad
o Systolic hypertension
o Bradycardia
o Irregular respiration
16
Q
What are primary brain injuries and when do they occur?
A
- Primary brain injuries can’t be affected by pre-hospital treatment, they occur at the time of impact, for example
o Extra cerebral injuries
Skull fracture, EDH, SDH and SAH
o Intra cerebral injuries
Concussion, contusion, compression, DAI, ICH
17
Q
List the 4 types of Skull Fractures
A
- Linear
o The most common type - Depressed
o Caused by small objects and high velocity settings - Open Vault
o Opening between the skull and brain tissue, has a high mortality associated - Base of Skull
o Seen in major trauma and is hard to see on an x-ray, the following clinical signs are used to diagnose.
Bruising over the mastoid process = Battle sings = # Temporal bone
Bruising on one or both orbits = racoon eyes = # Sphenoid bone
CSF leakage from the ears/nose
18
Q
Where does extradural haemorrhage occur and what are common causes?
A
- They occur in the space between the cranium and the dura mater, they are generally an arterial bleed. The middle meningeal artery is a common culprit for the bleed.
- Low velocity blows and deceleration injuries.
19
Q
Where does subdural haemorrhage occur and what re common causes?
A
- They are a haemorrhage between the dura mater and arachnoid mater, generally a venous bleed.
- They are associated with trivial trauma in the elderly and often seen with shaken baby syndrome.
20
Q
What are the classifications of a subdural haemorrhage?
A
- Acute o Develop within 48hr - Subacute o Develop within 48hr – 2 weeks - Chronic o Develop within weeks to months
21
Q
Where does subarachnoid haemorrhage occur and what are common causes?
A
- They are a haemorrhage into the CSF between the arachnoid mater and pia mater; they result in blood CSF and meningeal irritation.
- They are caused by trauma and also seen in aneurysm
22
Q
What are signs and symptoms of subarachnoid haemorrhage in a non-trauma setting?
A
- Thunderclap severe headache, nausea and vomiting, seizures and reduced GCS.
23
Q
In what forms of impact are a concussion seen and what occurs within the skull?
A
- Seen in mild to moderate impacts of the skull. There is movement of the brain within the skull were a subtle shearing of neurons occurs without any obvious signs of structural damage.
24
Q
What signs and symptoms are seen in a PT with a concussion?
A
- Brief alteration of consciousness <5min
- LOC often followed by periods of drowsiness/restlessness and confusion
- Retrograde/ante grade amnesia
- Headache, vomiting, transient visual disturbances, coordination defects
25
What is occurring in the skull to cause a contusion?
- Bruising to the cortex occurs which results in a structural change in brain tissue, these are worse than a concussion.
26
Where will the site of the contusion be seen in head trauma?
- It will be seen at the opposite site of injury.
27
What are signs and symptoms of a Contusion to the head?
- Seizure, hemiparesis (weakness of one side of the body), aphasia (language disorder), personality change and LOC
28
What occurs in the skull in a compression head injury?
- Haemorrhage and oedema occurs within the brain, this leads to structures being compressed or pressured, this leads to a loss of neuronal perfusion. These may lead to secondary head injuries.
29
What occurs in Diffuse Axonal Injury (DAI)?
- These are the most severe form of brain injury and result from shearing and rotational forces causing neuronal disturbances.
30
What are the 3 categories of DAI?
- Mild
o Coma for 6-25 hours
- Moderate
o Coma for >34 hours and abnormal posturing
- Severe
o Brainstem injury, prolonged coma and increase ICP
31
What occurs in an intra-cerebral haemorrhage and what are its general causes?
- >5ml of blood is collected in brain tissue; they may result from lacerations secondary to penetrating trauma or high velocity deceleration injuries.
32
What are secondary brain injuries?
- These injuries evolve and extend from the initial injury and are a result of increasing ICP and the bodies’ attempts to maintain homeostatic balance that further causes neuronal ischemia.
33
What are the major types of secondary brain injury?
- Hypoxia
- Hypotension
- Hypoglycaemia
- Hypercapnia
- Hypocapnia
34
Why are the 5 secondary brain injuries detrimental?
- Hypoxia
o Neurons need oxygen to maintain aerobic respiration and function normally
- Hypotension
o Neurons need adequate CBF in order to maintain oxygenation status
- Hypoglycaemia
o Neurons need adequate glucose supply to function
- Hypercapnia
o Increase C02 levels in the blood cause vasodilation and increased bleeding increasing ICP
- Hypocapnia
o Decreased C02 levels in blood cause vasoconstriction and reduced CBF leading to ischemia of the brain
35
What is ALS primary care in head injured PT?
- Maintain airway patency
- Ensure adequate breathing occurs
- Support the cardiovascular system
- Prevent or minimise secondary brain injury
- Protect the patient from further harm
- Transport an appropriate medical facility
- Have the patient transported by an appropriate skill set
36
Why is caution needed with head injured patients in regards to OPA, NPA and suctioning?
- OPA and suctioning may increase ICP and the NPA is contraindicated in base of skull fractures as they may enter the brain
