Wk 6 Flashcards
The nervous systems role
Maintain homeostasis
Responsible for our perceptions, behaviours and memories
Initiates voluntary movements
Responds rapidly to stimuli using nerve impulses
Role of brain
Perception and sensory stimuli
Voluntary motor responses
Homeostatic mechanisms
Only 2% of body weight yet uses 20% O2 in blood
Uses glucose for energy but doesn’t store extra supplies hence needs constant supply of O2 and glucose
Auto regulation: cerebral perfusion, blood flows through cerebral vessels to maintain optimum blood flow
The cerebral-spinal fluid
Circulates through subarachnoid space around spinal cord and brain
80-150mls CSF in CNS
Made in choroid plexus and absorbed by arachnoid villi
Protection: acts as shock absorber, buoyancy for brain
Circulation: nutrients to CNSand removal of waste
Meninges of the brain
Scalp Skull Periosteal dura mater Meningeal dura mater Arachnoid mater Subarachnoid space Pia mater Cerebral cortex
The components within the skull
Brain 80%
CSF 10%
Blood 10%
Sums of volumes of brain, csf and intracranial blood are constant = Monroe kellie doctrine
Primary brain injury
Occurs at moment of trauma
Includes contusion, damage to blood vessels, laceration of brain tissue and axonal shearing (shearing of nerve fibers)
Blood brain barrier and meninges damaged
Different regions of brain more sensitive to mechanical damage
Primary leads to secondary injury
Cause: blow to head, penetration, acceleration/deceleration
Concussion
Momentary interruption of brain function with or without loss of consciousness
Contusion
Bruise to the brain caused by blunt head trauma, results in permanent damage
Diffuse axonal injury
Primary injury with widespread microscopic damage: shifting, shearing, rotational, acceleration, deceleration injury, that stretch and or tear nerve cell processes within the brain
Haemotoma bleeding in the brain
Extradural/epidural: commonly arterial bleeds. Compression may be rapid
Subdural: commonly venous so slower to develop can be acute or chronic
Subarachnoid: aneurysm rupture in circle of willis
Intracranial: severe motion of the brain or develop from contusion. Eked rely and alcoholics more vulnerable
Secondary brain injury
Consequence of primary injury, occurs hours and days after
Plays large role in brain damage and death
Inflammation, swelling, oedema, raised ICP, reduction in cerebral blood flow and tissue oxygenation
Altered consciousness and coma
Consciousness: awareness of self and environment, requires arousal and awareness, often first sign of severe illness
Coma: state of unresponsiveness from which a patient can’t be aroused to produce meaningful response, absence of arousal and content, often problem with cerebral cortex or brain stem reticular activating system
Skeletal muscle weakness and paralysis may result from lesions in voluntary and sensory nerve pathways (upper and lower)
Upper: corticospinal and corticobulbar tracts, basal ganglia, cerebellar
Lower: peripheral nerves, mixed sensory and motor deficits, decreased muscle tone and flaccid paralysis
Intracranial pressure ICP
Pressure exerted within the skull and meninges by the contents of the skull
Normal 0-10mmhg
Above 15mmhg is abnormal
Cerebral perfusion pressure cpp
Blood pressure gradient across the brain, an estimate of cerebral blood flow
Cpp = map - icp
Cpp less than 60mmhg neuronal hypoxia and cell death
Causes of raised ICP
Trauma: swelling, bleeding and obstruction/ reduced blood flow
Bleeding: CVA, aneurysm, malformation
Infection: meningitis, encephalitis
Tumour: benign or malignant
Csf drainage blocked hydrocephalus: clot, debris, malformation
Symptoms of raised ICP
Headache: stretch on vessels
Changes in LOC/cognition: lack of O2 to cerebrum
Altered reaction/size of pupils: optic nerve comp
Projectile vomiting
Bradycardia, irregular pulse, increased BP, decreased RR (cushings triad- widening pulse pressure, increases arterial pressure to overcome increased ICP)
Seizures
Papilloedema swelling of optic disk
Assessment of pt
ABCDE Early detection of ICP can be lifesaving AVPU Glasgow coma scale Neuro obs Decorticate posturing and decerebrate posturing Mental status Pupil changes
Avpu
Alert/awake: eyes open and responding
Voice: needs verbal stimulus to open eyes and respond (drowsy)
Pain: needs physical stimuli to elicit response
Unresponsive: no response
GCS
3-8: coma/severe injury
9-12: moderate head injury
13-15: mild injury
Medical treatment of raise. ICP
ABCDE
Maintain cerebral perfusion (cpp>70mmhg) and oxygen delivery: Fluid resuscitation, map 90mmhg, cool pt
ICP monitoring: GCS 3-8, adverse signs, abnormal CT
ICP above 20-25mmhg
Brain injury surgery
Craniotomy: bone flap is temporarily removed from skull to access brain
Decompressive craniectomy: part of skull is removed to allow swelling
Nursing care of pt with raised ICP
ABCDE Oxygen Cool pt Breaks between care (10mins) Accurate measurement of BP, TPR, GCS and fluid balance Avoid oropharyngeal suction Communicate with patient Therapeutic touch Elevate head >30 degrees for venous drainage Neutral alignment Avoid hip flexion (increases intra thoracic pressure and affects venous drainAge) Treat constipation as it raises BP
Spinal cord injuries
Described at various levels and degrees of damage
Transient (full recovery)
Incomplete: contusion, laser action and compression of cord substance - range of effects
Transection of cords “complete” injury - total loss of function below site of injury
Cord oedema
Spinal shock
Cervical injury sites and their effect
Cervical: tetraplegia or quadriplegia, limited function, c1-3 results in loss of breathing
Thoracic: Paraplegia
Lumbar/sacral : decreased control of legs and hips, urinary system
Nursing management sci
ABCDE Treat as being spinal injury until ruled out Pt immobilised Spinks alignment X-ray, cT scan, MRI Airway and breathing are key Respiratory support Fluid resuscitation BP control Hr control Nutrition Skin care Pain relief
CVA/ cerebrovascular accident stroke
Sudden interference to brains blood supply due to a partial or complete occlusion of a cerebral artery
Ischaemia
Haemorrhage
Early signs and symptoms of TIA and stroke
Fast
Face: one sided weakness of face, tingling, headache, dimness of vision
Arms: one sided weakness
Speech: slurred, loss, difficult to understand
Time: call 911
Nursing management of stroke
ABCDE Oxygen Frequent neuro obvs Iv access and drug therapy Transfer to ct scan MRI IDC and fluid balance Position changes Range of motion exercises
Meningitis
Inflammation and infection of the Pia mater, arachnoid mater, and the CSF filled subarachnoid space
Viral is less severe
Bacterial invades CSF and sets up inflammatory response
Meninges thicken adhesions form and flow of CSF is affected
Signs and symptoms of bacterial meningitis
Fever and chills Headache Stiff neck and back Abdominal and extremity pains Nausea and vomiting Seizures Meningococcal meningitis rash Photophobia
Diagnosis and treatment of bacterial meningitis
ABCDE Organ support Antibiotics Corticosteroids Antipyretic X and anticonvulsants IV therapy Obs Vaccines
Encephalitis
Inflammation of the brain
Memory problems, hallucination. Tremors, seizures, headache
Antiviral agents, mechanical ventilation, corticosteroids, sedatives
Seizures
Transient neurological event of abnormal or excessive electrical discharges
Disturbances of motor function and autonomic visceral function, behaviour, consciousness
Nursing Management of seizures
ABCDE Protect airway Protect from injuries Bloods: glucose important Further investigation Antiepilectic medication
Myasthenia gravis
Autoimmune neuromuscular disease that causes fluctuation muscle weakness and fatiguability
Guillain barre syndrome
Acute inflammatory demyelinating polyneuropathy affecting peripheral nervous system
Triggered by acute infection
