coma, persistent vegetative state and brain death Flashcards
Define coma
A state of unrousable psychological unresponsiveness in which the subjects lie with eyes closed and show no psychologically understandable response to external stimulus or inner need
What 2 things does consciousness rely on
intact ascending reticular system
Functioning cerebral cortex
What is the ascending reticular activating system responsible for?
awakening and alerting element of consciousness
What is the functioning cerebral cortex responsible for?
content of that consciousness - awareness
What GCS score(s) is defined as a coma
less than 8
Causes of decreased GCS
sepsis, hypoxia, hypotension,
drug intoxication, renal failure
hypoglycaemia
seizures, damage to reticular activating system
Raised ICP eg hydrocephalus, tumour, stroke, haemorrhage
What is persistent vegetative state?
A state in which the brainstem recovers to a considerable extent but there is no evidence of recovery of cortical function
What is the locked in syndrome?
The patient has total paralysis below the level of the 3rd nerve nuclei and can open, elevate and depress eyes although no horizontal eye movement and no other voluntary movement
Give an example of when locked in syndrome could occur
Stroke in basilar artery denying pons of blood supply
Breathing - what does fluctuating breathing and depressed respiration suggest?
fluctuating - brainstem lesion
depressed - drug overdose
First resuscitation and investigation of patient
ABC
Circulation - investigations
blood - glucose, biochemistry, haematology, blood gas and toxicology
blood pressure, pulse, temperature, IV access, stabilise neck
MENINGITIS
What is always important to discount in a coma patient?
meningitis
3 types of history for coma
expected progression eg renal failure
unpredictable with no known cause
unexpected eg head injury
Some monitoring of the patient would include..
temperature respiratory and heart rate bp abdomen meningism fundal examination
meningism triad
neck stiffness
photophobia
headache
3 neurological assessment of coma
GCS
brainstem function
motor function and reflexes
How would you test brainstem function?
pupillary reaction, spontaneous eye movement, corneal response, occulovestibular response, respiratory pattern, dolls eye
Testing motor function and reflexes
motor response
muscle tone
tendon reflexes
seizures
GCS - 3 parts
eye opening
best verbal response
best motor response
GCS - eye opening grading
4 = spontaneous 3 = to voice 2 = to painful stimuli 1 = none
GCS - best verbal response grading
5 - orientated 4 - confused 3 - inappropriate 2 - incomprehensible sounds 1 - none
GCS - best motor response grading
6 = obey commands 5 = localise to pain 4= withdraw from pain 3= flex 2= extend 1= none
For each of the 3 categories what score represents a coma?
eyes - 2 or less
voice - 2 or less
motor - 4 or less
Causes of coma without focal signs or meningism
anoxia, seizure/epilepsy, ischaemia, intoxications, metabolic disturbances, systemic infections, hyper/hypothermia
Investigation of coma without focal signs or meningism
toxicology screen - alcohol blood sugar and electrolytes hepatic and renal function blood gas and acid base assessment blood pressure CO poisoning
3 main causes of coma without focal signs but with menigism
subarachnoid haemorrhage
meningitis
encephalitis
Investigation of coma with menigism only
CT head
lumbar puncture
4 things to look for in lumbar puncture in coma with meningism
cell count
capsular antigen test
glucose level
appearance
4 main causes of coma with focal brainstem or lateralising cerebral signs
cerebral tumour, haemorrhage, infarction or abscess
Investigation of coma with focal signs
MRI/CT
metabolic screen, lumbar puncture, EEG
Medical causes of coma lasting more than 5 hours
drug/alcohol ingestion
hypoxia eg MI
haemorrhage eg infarction
metabolic eg diabetes
Prognostic factors in coma outcome
age cause of coma depth of coma duration of coma clinical signs
Continuing care of patients in a coma includes
maintain vital functions care of skin and avoid pressure sores prophylaxis of DVT bladder and bowel control seizures and prevent contractures consider locked in syndrome
Why can head injury lead to focal neurological signs?
diffuse axonal injury
contusion - bruising
intracerebral haematoma
extracerebral haematoma eg extradural and subdural
How to manage head injury
stabilise cervical spine ABC GCS - intubate and ventilate treat raised ICP cranial imaging neuro observations
How to treat raised ICP
surgery to relieve pressure osmotic agent eg mannitol head at angle for venous return reduce pain maintain good PO2 and reduce PCO2 reduce metabolism eg barbiturates
