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Traumatic brain injury exam 3
Terms in this set (17)
Principles to consider when caring for any person with any type of intracranial issues are:
· the brain, blood and CSF occupy a determined amount of space within a hard box (the skull).
· because these substances are contained inside a closed space, pressure is created.
This pressure is known as ICP - intracranial pressure.
What would happen to ICP if the brain space was increased?
What would happen to ICP if cerebral edema was present?
Provide a specific value.
ICP would increase.
If normal ICP = 5-15 mm/Hg
then an increased ICP would be greater than 15 mm/hg
Brain cells must have oxygen; anaerobic metabolism is not an option.
What happens if a brain cell is without oxygen?
How long (time frame) before this happens?
with no oxygen and no ATP production the brain cells swell
When a cell swells there is decreased space for blood to flow --> causing decreased blood flow to nearby cells --> causing more nearby cells to swell
BRAIN SWELLING CAUSES MORE BRAIN SWELLING AND ICP GOES UP
4-6 minutes - short time.
Other organs will tolerate low oxygen better than the brain
It has been identified how low O2 causes cerebral edema, now identify specific mechanisms that can cause cerebral edema and increasing ICP
Identify the mechanisms that can cause brain cells to be without oxygen or to swell (cause edema).
Without O2 from thrombotic or embolic stroke can cause cellular swelling
Thrombotic stroke - narrowing of artery by plaque causing clot to form and block passage of blood in artery
Embolic stroke - clot in brain artery that lodges and blocks flow of blood
Hemorrhagic stroke - a burst blood vessel that allows blood to seep into and damage brain tissues until clotting to shut off leak
The brain has compensatory mechanisms to ensure survival known as
- the ability to maintain a constant blood flow by increasing (vasodilation) or decreasing (constriction) vessel diameter
MAP must be 70-150 for this mechanism to work/function.
Anytime brain is below 70 it is difficult for it to do auto-regulation and maintain constant blood flow
How does a nurse know if cerebral perfusion is adequate?
Is there constant blood flow and cerebral perfusion to brain
Calculate cerebral perfusion pressure (CPP)
CPP = 70 - 100 mm/Hg
Formula = CPP = MAP - ICP
ICP can only be measured if the patient has a ventriculostomy - a hole is drilled through the skull and a tube/bolt is placed in the ventricle of the brain = ICP can then be measured.
On exam if you are given ICP and BP calculate CPP
If given BP calculate MAP
1. BP = 120/80 ; ICP = 15
2. BP = 90/60 ; ICP = 15
3. BP = 120/70; ICP = 35
To calculate MAP:
systolic BP + diastolic BP + diastolic BP then divide by 3
120 + 80 + 80 = 280/3 = 93.33 (get CPP by subtracting 15 = 78.33)
Abnormal ICP but a low BP creates a bad CPP
a normal BP and high ICP creates a bad CPP
CPP greater than or equal to 70 mm/Hg. If the CPP is less than 70 = BAD.
A CPP less than 50 mm/hg decreased brain perfusion = REALLY BAD
Systolic BP greater than or equal to 90 mm/Hg
MAP greater than or equal to 70 mm/Hg
1. BP = 120/80 ; ICP = 15 --> CPP= 78.33
2. BP = 90/60 ; ICP = 15 --> CPP = 55
3. BP = 120/70; ICP = 35 --> CPP = 51.67
Low CPP not getting enough oxygen
A 22-year-old construction worker arrives in the ED after receiving multiple blows to his head from a hammer. He experienced a brief altered level of consciousness at the accident scene but is now awake and complaining of "a bad headache". He denies any previous medical problems. A deep head laceration is noted.
Assessment data: airway and breathing fall within normal limits. C-spine cleared by physician.
Vital Signs: RR 20, regular, unlabored, B/P 140/70 mm/Hg, HR 98 b/min
GCS = 15
What should concern you regarding his initial complaint?
the patient suffered a blow to head and scalp laceration.
Any trauma to skull, scalp or brain is classified as a head injury.
Although the primary injury occurred to the scalp, ADDITIONAL BRAIN AND SKULL INJURY SHOULD BE SUSPECTED FROM THE RESULTING EDEMA (which may occur later)
with any head/brain injury this patient is at risk for increased ICP and altered CPP
The nurse now notes periorbital edema and eccymosis and postauricular eccymosis -bruising around the eyes (racoon's eyes) w/bruising behind the ears (battle's sign). A clear nasal drainage is also noted.
Identify the clinical significance of these assessment findings.
Clinical manifestations are found with linear skull fracture - suspect skull fracture if periorbital edema & eccymosis (bruising around eyes - raccoon's eyes) and postauricular eccymosis (bruising behind ears -battle signs)
Rhinorrhea or otorrhea (drainage from the nose or ear) occurs with a skull fracture
- Assess the drainage
- if the bloody drainage contains CSF, the CSF will separate into a halo with blood in center = CSF leak
- if drainage is clear, dip a dextrostix into the drainage. CSF will test positive for glucose. Snot does not test positive for glucose.
- ANY blood drainage will always test positive for glucose b/c blood contains glucose
The patient, suddenly, begins to vomit. You turn his head to the side ensuring that he does not aspirate. He is less responsive.
What are your priority interventions?
During the initial assessment his airway and breathing were within normal limits. Traumatic brain injuries can depress the respiratory center in the brain causing respiratory hypoventilation or hypercapnic respiratory failure.
Maintain a patent airway (A)
- Assess for blood or debris
- Assess swallowing
- If patient is vomiting - have suction available
Assess for altered breathing patterns and oxygenation (B)
- Prepare for intubation
- Decreased level of consciousness + vomiting = unable to protect their airway
- Provide support to respiratory function
- Reassess vital signs
- BP 140/70
- HR 58
- Cap refill
- Insert IV
Complete neuro assessment
- Glasgow coma scale: level of consciousness (D - disability), pupil size/reactivity
- Their level of arouse ability is decreased - only makes unidentifiable sounds, opens eyes and withdraws to painful stimuli
GCS = 8
Opens eyes to pain, not applied to face - 2
Incomprehensible speech - 2
Withdraws from pain
ABC prioritization is always a MUST. Exam question will ask what will the nurse do first? Level of consciousness is important BUT will NEVER be more important than ABC. Report any changes in LOC
What might these clinical manifestations (vomiting and ↓LOC) indicate?
These manifestations are signs of increasing intracranial pressure
- Decreased level of consciousness (early sign)
- Vomiting without nausea
- Widened pulse pressure with increasing systolic BP (systolic - diastolic = pulse pressure/ 120-70 = 50/ 140-70 = 70)
- Changes in respiration rate and pattern (rapid then slow - weird patterns)
= all three signs of cushing's triad & rising ICP
- Ocular/pupil signs (one might be big or small, one might respond to light or not)
- Decreased motor function or abnormal posturing in response to stimuli - decorticate posturing (flexor) or decerebrate posturing (extensor) - may not respond at all (flaccid)
WRITE ON EXAM SHEET
What nursing measures are used to prevent/manage increased ICP?
- HOB 30-45 degrees (NOT greater than 45 degrees - heigh promotes venous outflow from the brain.
- Higher than 45 degrees increases intra-abdominal/intrathoracic pressure --> increased ICP
- Keep neck straight to promote venous outflow
- Keep BP < 150
- Space out stressful activities
- Protect airway
- Check PT/PTT stat and correct coagulopathy w/ vit K subQ & FFP immediately with bleeds
- With mannitol = osmotic diuretic = shifts fluid = decreases edema (if not hypotensive)
- Keep PaCO2 25-35 mmHg (increased CO2 = cerebral vasodilation --> increased ICP but decreased CO2 = cerebral vasoconstriction --> can cause ischemia --> need that just right blood vessel balance)
- Remove CSF via ventriculostomy
- Surgical evacuation of clot/tumor/blood
What is the consequence of ↑ ICP?
Main danger of increased ICP
- is it can cause ischemia (tissue death) by decreasing cerebral perfusion pressure
As the ICP INCREASES, CEREBRAL PERFUSION FALLS
The body responds to a fall in CPP by increasing systemic blood pressure and dilating cerebral blood vessels.
- This results in increased cerebral blood volume, which increases ICP, lowering CPP further and causing vicious cycle.
- This results in widespread reduction in cerebral flow and perfusion, eventually leading to ISCHEMIA AND BRAIN INFARCTION
Because of his worsening symptoms and decreased level of consciousness (GCS now 8), the patient is urgently sent to the xray department for a head CT
Because of his worsening symptoms and ↓ LOC (GCS now 8), the patient is urgently sent to the x-ray department for a head CT.
A linear skull fracture and epidural hemorrhage are identified.
- An epidural hemorrhage occurs when a traumatic force causes a skull fracture à this tears a blood vessel --> arterial bleeding occurs.
Classic symptoms are a brief loss of consciousness followed by alertness followed by ↓ LOC.
An epidural hemorrhage is a neurologic emergency. The patient will be taken to the OR for a surgical evacuation of the clot and the prevention of further bleeding. The neurosurgeon also inserts a ventriculostomy to monitor and manage ICP and CPP.
The patient returns from the OR on mechanical ventilation. The nurse is managing the ICP by draining the CSF. Mannitol (an osmotic diuretic) has been administered IVP to control cerebral edema and cause diuresis.
His blood pressure, heart rate and ABGs (CO2) are within accepted parameters. Neuro checks, done every hour, are unchanged. GCS = 6.
Additional HCP orders read: Dilantin-125 Suspension TID per orogastric tube (OGT), OG tube to low suction. Clamp 1 hour after each med admin
Provide indication for dilantin order
Dilantin is an anti-seizure medication
Patients with any intracranial problems are at risk for seizures
A seizure (or fever or pain) will cause an INCREASE IN METABOLIC RATE of the brain cell, increasing the O2 demand of the cell
Why was an OGT inserted instead of an NG tube?
To avoid placing the tube in the intracranial space
An NG tube should not be inserted if a skull fracture is suspected
The nurse maintains strict aseptic technique while draining CSF from the ventric. HR = 70; B/P = 140/70; ICP = 36. The patient is mechanically ventilated. Volume controlled A/C; TV 600, Rate; 14 (no spont resp); FiO2 40%; PEEP 5; SaO2 100%.
Calculate the CPP. Would perfusion to the brain (O2 delivery) be improved by increasing the FiO2 to 50%?
CPP = 57.33 the CPP is < 60.
- Perfusion to the brain is decreased.
- Brain cells are lacking O2 and dying.
- BUT SaO2 (measured oxygen saturation) is 100%.
There is plenty of O2 in the blood.
The O2 cant be delivered to the brain cells because of the ICP is too high causing decreased perfusion.
The ICP must be lowered by draining off CSF
Why is it important to use strict aseptic technique when manipulating the ventriculostomy drainage system (hint what vital sign is missing)?
This patient has an scalp laceration and a skull fracture.
He is at risk for an infection.
An infection with a fever would increase his metabolism, increasing metabolic wastes which produce cerebral vasodilation, this worsens cerebral edema.
In addition infection and fever (anxiety and pain) increase oxygen demand; this may worsen brain tissue ischemia
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