Coma Flashcards
What is 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 does consciousness depends on?
- An intact ascending RETICULAR ACTIVATING SYSTEM to act as the alerting or awakening element of consciousness
- A functioning CEREBRAL CORTEX OF BOTH HEMISPHERES which determines the content of that consciousness
What can be the causes of decreased GCS?
Toxic/ metabolic states
- Hypoxia/ hypercapnia/ sepsis/ hypotension
- Drug intoxication/ renal or liver failure
- Hypoglycaemia, ketoacidosis
Seizures
Damage to reticular activating system
Causes of rased intracranial pressure:
-Tumour, stroke, EDH, SDH, SAH, hydrocephalus
What is a persistent vegetative state?
A state in which the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function
There is arousal and wakefulness but the patient does not regain awareness or purposedul behaviour of any kind
What is “locked in” syndrome?
The patient has total paralysis below the level of the third nerve nuclei and, although able to pen, elevate and depress the eyes, has no horizontal eye movements and no other voluntary eye movement
The diagnosis depends on recognising that the patient can open their eyes voluntarily and signal numerically by eye closure
What is involved in resusitation of unconscious patients?
Airway
Breathing
- Depressed respiration (drug overdose, metabolic disturbances)
- Increased respiration (hypoxia, hypercapnia, acidosis)
- Fluctuating respiration (brainstem lesion)
Circulation
Blood samples
- glucose, biochemistry, haematology, blood gas
- Toxicology
Establish baseline blood pressure, pulse, temperature, IV access and stabilise the neck
Examine for evidence of meningitis- treat on suspicion
What is usually present in the history of patients presenting with decreased conscious state?
?Predictable progression of underlying illness (liver failure, renal failure, epilepsy, diabetes)
?Unpredictable event in patient with previously known disease
?Totally unexpected event
-Head injury, sudden collapse, limb twitching, prev history of drug or alcohol abuse
What shouls you keep an eye out for on examination and monitoring?
Temperature Heart rate, BP, CVS Respiration Skin, breath (ketones) Abdomen Meningism Fundal examination
How is a Neurological assessment of a coma carried out?
Glasgow coma scale
Brainstem function
Motor function + reflexes
How is someone classed as being in a coma using GCS?
Patients who fail to show eye opening in response to voice, perform no better than weak flexion in response to pain and make at best only unrecognisable grunting noises in response to pain are regarded as being in coma
Eye opening (2 or less) Verbal resonse (2 or less) Motor response (4 or less)
GCS = 8
How do you test brainstem function?
Pupillary reactions (II + III)
Corneal reactions (V + VII)
Spontaneous eye movements (III, IV + VI)
Oculocephalic responses (doll’s eye) (III, IV, VI, VIII)
Oculovestibular responses (III, IV, VI, VIII)
Respiratory pattern (Medullary centre)
What may cause a coma wihout focal or lateralising signs and without meningism?
- Anoxic/ ischaemic conditions
- Metabolic disturbances
- Intoxications
- Systemic infections
- Hyperthermia/ Hypothermia
- Epilepsy
What investigations can you carry out in coma without focal or lateralising signs and without meningism?
Toxicology screen including alcohol level
Measure blood sugar and electrolytes
Assess hepatic and renal function
Acid-base assessment and blood gases
Measure blood pressure
Consider carbon monoxide poisoning
What may cause coma without focal or lateralising signs but with meningism?
Subarachnoid haemorrhage
Meningitis
Encephalitis
What investigations would you carry out in coma without focal or lateralising signs but with meningism?
CT head scan
Lumbar puncture
- Appearance
- Cell count
- Glucose level
- Capsular antigen tests
What may cause coma with focal brainstem or lateralising cerebral signs?
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abcess
What investigations should you carry out in a coma with focal brainstem or lateralising cerebral signs?
CT or MRI obligatory
If CT/MRI not diagnostic, then investigate as for other causes of coma e.g. including:
- Metabolic screens
- Lumbar puncture
- EEG
What are the “medical” causes of coma lasting more than 5 hours?
40% due to drug ingestion +/- alcohol
25% due to hypoxia (e.g. secondary to MI
20% due to cerebrovascular event, either haemorrhage or infarction
15% metabolic e.g. diabetes, hepatic failure, renal failure, sepsis, hypercapnia/ hypoxia
What are the factor affecting outcome in coma?
Age Cause of coma Depth of coma Duration of coma Certain clinical signs, the most important of which are the Brain stem reflexes
How many patients in a non-traumatic coma for more than 6 hours will make a good or moderate recovery?
Overall, only 15% of patients
The other 85% will die, remain vegetative or reach a state of severe disability in which they remain dependent
In non traumatic coma over 6 hours, good recovery is seen in….
35% of those with underlying metabolic cause
11% of those with hypoxic ischaemic insult
7% of those with cerebrovascular disease
How do you continue the care of patients in a coma?
- Maintain vital functions
- Care of skin, avoidance of pressure sores
- Attention to bladder and bowel function
- Control of seizures
- Prophylaxis of DVT, peptic ulceration
- Prevention of contractors
- Consider “locked in” syndrome
Head injury can lead to focal neurological signs/ Epilepsy due to what?
Diffuse axonal injury
Contusion
Intracerebral haematoma
Extra-cerebral haematoma
- Extra-dural haematoma
- Sub-dural haematoma
How do you manage head injury?
- Stabilise cervicle spine
- Airway/ Breathing/ Circulation
- If GCS 8 or less intubation + ventilation
- Treat raised ICP
- Cranial imaging - may need decompressive surgery or removal of haematoma
- Neuro-observation
how do you treat raised ICP?
Surgery to releave pressure
-Haematoma, ventricular shunt
Osmotic agents e.g. mannitol
Nurse with head at 30-45% (venous return)
Reduce pain
Maintain good PO2, reduce PCO2
Reduce metabolism (reduce temperature, barbiturates)
