TBI - 8 (2 SATA) Flashcards
Physiologic Review of the neurological system
- Central Nervous System and Peripheral Nervous System
- Brain
- Brainstem – reflexes, vital signs
- midbrain, pons, medulla oblongata
- Cerebellum – muscle movement, balance, control
- Cerebrum – Largest part, 2 hemispheres, 4 lobes
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
Pearson (2nd Ed.) Nursing: A Concept-based Approach to Learning, p.688-699
Physiologic Review (cont.) Protective structures of the brain
- Skull – bony protection to the brain that does not allow swelling
- Meninges – protective connective tissue made out of three membranes
- Cerebrospinal fluid – clear fluid in the subarachnoid space
- cushions the brain
- maintains chemical balance
Intracranial Pressure (ICP)
- ICP is the pressure inside the skull
- For adults >20 warrants immediate treatment intervention
- Maintained via balance of blood volume, brain tissue, and CSF
- More clearly described in Monroe Kellie Doctrine
Monroe Kellie doctrine
- The body attempts to maintain equilibrium when ICP increases
- Decrease blood supply to brain to compensate
- Leads to a decrease in tissue perfusion of brain
-bleed/tumor/seizure/liver failure
Physiological importance of traumatic brain injury (tbi)
- Brain is in a “closed system” within the skull
- Impacts to the head can cause the brain to impact against the skull (coup and countercoup)
- Bleeding within the skull can cause a feedback loop where increases in pressure reduces blood flow to the brain
- Swelling to brain or surrounding tissues may also cause the feedback loop reducing blood flow to the brain.
[coup - injury on same side of impact
countercoup - injury on opposite side of impact]
How do we monitor ICP?
- Invasive pressure transducer placed in the ventricles, subarachnoid space, epidural space
- Several varieties – best is the ventriculostomy
- Some noninvasive options but not suitable for long term monitoring and are generally not accurate
infection risk - meningitis
brain / vessel injury
bleeding
Measuring ICP
Ventriculostomy
- Measured via the CSF in the ventricles of the brain
- Normal is 5-15mmHg in adults
- Above 20mmHg requires immediate intervention
•ANYTHING OVER 30mmHg IS LIFE THREATENING
hydrocephalus - fluid on brain
spine - not as accurate reading as brain
Measuring Cerebral Blood Flow
•Start with MAP – Mean Arterial Pressure [average pressure in arteries throughout cardiac cycle]
•Equation: MAP = [(2 x diastolic)+systolic] / 3
Diastole counts twice as much as systole because 2/3 of the cardiac cycle is spent in diastole.
A MAP of about 60 is necessary to perfuse coronary arteries, brain, kidneys.
•Usual range: 70-110
•Practice
120/80 = MAP __93____
100/54 = MAP __69____
142/96 = MAP __111____
Cerebral Perfusion Pressure (CPP)
- CPP – pressure needed to ensure blood flow to brain
- CPP = MAP – ICP
- Normal CPP is between 60-100mmHg
- <50mmHg is deadly
CPP ↑ 70 = greater outcome
Ventriculostomy Nursing Care
- Keep transducer set at “0” unless otherwise ordered, keep level with patient’s head
- Avoid anything that might impair drainage
- Monitor insertion site
- Transducer and drainage system are external
- Mean pressure measured at end of expiration
foramen magnum
- do not get out of bed
- do not reposition in bed
~125-150ml spinal fluid in body
~20ml/hr produced
Clinical Manifestations of ↑ ICP
- Δ in LOC [anxiety, restlessness, lethargy, repeating questions]
- Cushing’s Triad
- Ocular signs (papilledema / pupillary response changes / impaired eye movement)
- ↓ motor function or posturing
- Headache
- Vomiting
- Changes in speech
- Seizures
- Hemiparesis
Infants •Bulging fontanels •Cranial suture separation •↑ head circumference •high pitched cry •Projectile vomiting / reflux
Glascow Coma Scale
Eye Opening Response:
• 4 → Eyes open spontaneously 4 points
• 3 → Eyes open to verbal command, speech, or shout
• 2 → Eyes open to pain (not applied to face)
• 1 → No eye opening
Verbal Response:
• 5 → Oriented
• 4 → Confused conversation, but able to answer questions
• 3 → Inappropriate responses, words discernible
• 2 → Incomprehensible sounds or speech
• 1 → No verbal response
Motor Response:
• 6 → Obeys commands for movement
• 5 → Purposeful movement to painful stimulus
• 4 → Withdraws from pain
• 3 → Abnormal (spastic) flexion, decorticate posture →│←
• 2 → Extensor (rigid) response, decerebrate posture ←│→
• 1 → No motor response
Minor: 13-15
Major: 9-12
Severe: 3-8
3-rain dead
8-call Organ Procurement - req’d by law
12-intubate - protect airway
7-coma
Pulse Pressure
- Pulse Pressure – measures expansion of arteries in response to the volume of blood ejected during systole
- PP=SBP-DBP
- BP of 120/80 then PP=40
Pulse Pressure
- Pulse Pressure – measures expansion of arteries in response to the volume of blood ejected during systole
- PP=SBP-DBP
- BP of 120/80 then PP=40
Cushing’s triad
Cushing’s triad is a late sign
- Bradycardia
- Hypertension with widening pulse pressure
- Irregular, shallow respirations
•Monitor for Cushing’s Triad in ALL brain injury pts
Ocular Changes
- Anisocoric – pupil of one eye differs in size from the other
- Papilledema – swelling of optic disc (blanching)
- Pupillary reaction changes Fixed, bilateral, dilated pupils – very bad, poor prognosis, very ominous
Motor Function
- Assess motor movement, function, coordination
- We evaluate each extremity separately if they are able to follow commands
- Response to stimuli
- Decorticate - abnormal flexion (in)
- Decerebrate – abnormal extension (out)
usually not purposeful movement
TBI
Initial Management
- AIRWAY
- If GCS<8 intubate “less than 8, intubate”, or if any question about airway management
- If trauma, immobilize cervical spine
- Pulse ox, vitals, neuro checks, IV
- Check blood glucose (bring back to normal to rule/out)
- CBC, electrolytes, ABGs, LFTs, UA, blood culture if febrile, UDS, ETOH
Diagnostics
- X-Ray – just bone
- CT Scan – brain and soft tissue
- MRI – gives cross section view, like a slice of bread
- Angiogram – identifies ruptured, blocked, etc. blood vessels
- EEG – electroencephalograph – measures electrical activity in brain (life support determination)
Drug Therapy
- Loop diuretics (Mannitol)
- Corticosteroids – primarily dexamethasone
- Barbiturates – pentobarbital
- Phenytoin – anti-convulsant
- Sedatives + analgesics – morphine, fentanyl, Propofol (↓ vasoconstriction)
all given IV - NO PO even if awake
Therapy
Mannitol
- Go to drug for ↑ ICP – reduces cerebral swelling and edema
- Plasma expander – reduces viscosity of blood
- Osmotic diuretic
- Watch for hypotension, renal impairment
- Other hypertonic solutions may be used
•*MAY MAKE INTRACRANIAL HEMORRHAGE