Coma, PVS, Brain death Flashcards
What is a coma?
- unrousable
- psychological unresponsiveness
- eyes closed
- Does not respond to external/internal stimuli
What are the 2 factors which consciousness depends on?
- Cortex for awareness of environment/ content
- Reticular ascending pathway for the awakening system
Causes for decreased consciousness
- Metabolic/toxic
- Seizures
- Damage to reticular activating system
- Causes for raised ICP
What are examples of metabolic/toxic causes for decreased consciousness ?
- Hypoxia
- Hypercapnia
- Drug intoxication
- Hypoglycemia
What happens during persistent vegetative state
Brainstem recovers but cortex does not
There is arousal and wakefulness
There is no awareness or purposeful behaviour
What happens during locked in syndrome?
- Total paralysis below the third cranial nerve nuclei
- Can elevate and depress eyes
- Cannot move eyes horizontally
Stages of Resuscitation
- Airway
- Breathing:
- Hyperventilation : hypoxia, hypercapnia
- Hypoventilation : drug overdose
- Fluctuating: brainstem lesion
-Circulation :
Take blood samples
Establish Pulse, temperature, IV access and stabilise the neck
Examine for presence of meningitis
- History : predictable/ unpredictable incident
- Examination and monitoring
What need to be monitored in resus
- Temperature
- Heart rate
- Blood pressure
- Respiration
- Abdomen
- Meningism
- Fundal examination
Stages of a neuroexamination in a coma patient
- GCS
- brainstem function
- motor function
GCS in a coma patient.
Less than 8
Will not open eyes in response to pain
Grunting or absent vocal response
Weak flexion in response to pain
Brainstem function testing
- Pupillary response
- Corneal response
- Spontaneous eye movements
- Oculo-cephalic movements
- Oculo-vestibular responses
- Respiratory pattern
Testing motor function
- Motor response
- Motor tone
- Tendon reflex
- Seizures
3 Different types of coma
- No focal laterising signs, no meningism
- Menigism, no focal lateral signs
- Focal laterising signs
Causes of coma with meningism
SAH
Meningitis
Encephalitis
Investigation of coma with meningism
CT scan Lumbar puncture: -Apperance -Cell count -Glucose level -Capsular antigen tests
Causes of coma with no signs
Ischaemic/anoxic conditions Metabolic disturbance Intoxication Hyperthermia/hypothermia Systemic infection Seizures
Investigation of coma with no signs
Toxicology for alcohol Blood sugar and electrolytes Hepatic and renal function Acid-base assessment Blood pressure Carbon monoxide levels
Causes of coma with focal laterising signs
Cerebral tumour
Cerebral hemorrage
Cerebral infarction
Cerebral abscess
Investigation of coma with focal laterising signs
CT/MRI
If these are not diagnostic: Metabolic screens, LP, EEG
Medical causes of a coma
- Drug ingestion
- Hypoxia e.g. following MI
- CVS event e.g. hemorrage/infarction
- Metabolic e.g. diabetes, renal failure
Prognosis of a coma
- Only 15% of patients in a non-traumatic coma lasting more than 6 hours will make a good- moderate recovery
- Recovery is seen most in those whose cause way: metabolic, Hypoxic ischaemic, CVS related
- The rest die, remain in a vegetative state or remain severely disabled
Factors affecting the outcome of a coma
- Age
- Depth of coma
- Cause of coma
- Duration of come
- Clinical signs such as brainstem reflexes
Care of those in a coma
- Maintainance of vital function
- Care of skin
- Attention to bladder
- Control of seizures
- Prophylaxis of DVT, peptic ulceration
- Prevention of contractors
- Look for locked- in syndrome
Head injury consequences
- Diffuse axonal injury
- Contusion
- Intracerebral hematoma
- Extracerebral hematoma: extra-dural/ sub-dural
Difference on a CT between a subdural and extra-dural hemorrage
Sub-dural: ellipse
Extra-dural: concave
Management of a head injury
Stabilise cervical spine ABC If GCS <8 then intubation/ventilation Treat ICP Imagining may reveal need to decompress or remove a hematoma Neuro-observation
Treatment of increased ICP
Surgery to relieve pressure Osmotic agents e.g. mannitol Nurse with head at 30-45 %- venous return Reduce pain Maintain good PO2, reduce PCO2 Reduce metabolism
