Assessment of patient with reduced consciousness Flashcards
Definition of coma
Coma is a total absence of awareness of both self and the external environment
*those who do not open eyes to pain, do not move spontaneously, do not form recognisable words
Clinical signs of coma
- hypnosis
- amnesia
- areflexia
- analgesia
What anatomical structures are involved in consciousness?
- Reticular Activating System
- Brain stem
- Cerebral Cortex
What’s NMDA receptor?
excitatory neurotransmitter receptor e.g. glutamate
What’s needed to maintain consciousness?
- anatomical structures: reticular activating system, brain stem, cerebral cortex
- biochemicals: GABA-A, NMDA, noradrenaline
- cerebral metabolism
- cerebral blood flow
- co-ordinated electrical activity
Common causes of altered consciousness
- neurological
- toxicological
- endocrine/metabolic
What is the most important in making the diagnosis of the cause of reduced LOC?
- history -> the most important
- PMH
- examination
- bloods -> only helpful in small fraction of cases
UNCONSCIOUS - memonic for differentials in unconscious patient
U - units of insulin
N - narcotics (e.g. opioids)
C - convulsions
O - oxygen = hypoxia
N - non - organic (e.g. functional vs non-functiona;)
S - stroke
C - cocktail (overdose)
I - ICP
O - organism
U - urea
S - shock
COMA - memonic for differentials in unconscious patient
C- carbon dioxide or carbon monoxide (excess)
O - overdose
M - metabolic
A - apoplexy (unconsciousness as a result of cerebral haemorrhage or stoke)
What GCS would be a cut-off for intubation?
GCS of 8 or lower
What’s the first component of the assessment of the unconscious patient?
Airway
- assess
- call anaesthetics if needed
- temporary measured e.g. Gadel
What if a patient is ‘snoring’?
May indicate airway obstruction - may need to open the airway
Oropharyngeal airway:
- advantages and usual use
Oropharyngeal airway
- Easy to insert and use
- No paralysis required
- Ideal for very short procedures
- Most often used as bridge to more definitive airway
Laryngeal mask
- advantages / disadvantages
- use
Laryngeal mask
- Widely used
- Very easy to insert
- Device sits in pharynx and aligns to cover the airway
- Poor control against reflux of gastric contents
- Paralysis not usually required
- Commonly used for wide range of anaesthetic uses, especially in day surgery
- Not suitable for high pressure ventilation (small amount of PEEP often possible)
Tracheostomy
- use
- advantages and disadvantages
Tracheostomy
- Reduces the work of breathing (and dead space)
- May be useful in slow weaning
- Percutaneous tracheostomy widely used in ITU
- Dries secretions, humidified air usually required
Endotracheal tube
- use
- advantages
Endotracheal tube
- Provides optimal control of the airway once cuff inflated
- May be used for long or short term ventilation
- Paralysis often required
- Higher ventilation pressures can be used
What do we need to check and why after insertion of endotracheal tube?
Errors in insertion may result in oesophageal intubation (therefore end tidal CO2 usually measured)
What are examples of adjunct airway devices?
Adjuncts:
- oropharyngeal
- nasopharyngeal
- supraglottic
Examples of definitive airway devices
Definitive
- endotracheal tube
- cuffed tracheostomy
What is the advantage of cuffed tracheostomy over the endotracheal tube in the management of the unconscious patient in A&E?
With endotracheal tube pt can aspirate on food/drinks they have eaten
What if reduced LOC patient is vomiting?
- head tilt
- suction
3 ‘Es’ in assessment of BREATHING?
Effort, efficacy, effects
- Effort: RR, accessory muscles
- Efficacy: cyanosis, spO2, ABGs (pO2 and pCO2)
- Effects: consciousness
Possible causes of increased RR
Increased RR
- hypoxia
- brainstem herniation
- metabolic acidosis
- OD
Possible causes of decreased RR
Decreased RR
- opiate
- sedative OD
- head injury
Component of ‘circulatory’ assessment in ABCD?
Assess:
- pulse
- BP
- cap refill time
- ECG
Treatments used in ‘C’ component of ABCD
- IV access
- IV fluids -> to increase venous return to the heart
- +/- inotropes
- anti-arrhythmias
- if hypertension -> treat underlying cause (e.g. increased ICP)
Why ‘hypertension’ may be needed?
To maintain perfusion to the brain
Glasgow Coma Score
Two scales used to assess consciousness (just name)
- AVPU
- GCS
Possible causes for small and reactive pupils
Small but reactive pupils:
- metabolic encephalopathy
- midbrain herniation
Pinpoint and fixed pupil - what are the possible causes?
* fixed - non reactive to light
- pontaine lesion
- opiates
- organophospahtes (chemicals)
Dilated and reactive pupils - causes
Dilated and reactive
- metabolic
- midbrain
- ectasy
- amphetamines
Dilated and fixed pupils - causes
Dilated and fixed pupils
- ictal
- hypoxia
- ischaemia
- hypothermia
- anticholinergics
Unequal, but small and reactive pupils - a potential cause
Horner’s syndrome
unequal, dilated and fixed pupils - potential causes
- III n. palsy
- uncal herniaiton (transtentorial brain herniation)
Components of ‘D’ assessment (ABCD)
- Pupils
- glucose level (check BM!)
- rash
- pyrexia/ temperature
- trauma evidence
- ‘what’s in the pockets’?
1st line blood investigations unconscious patient
- Glucose
- ABG
- Electrolytes: U&Es, calcium, magnesium
- LFTs
- TFTs
- Poisons: Paracetamol, Salicylate levels
- FBC, CRP
What (other than blood) Ix to do in the unconscious patient?
- urine
- x-ray
- CT head
What’s things (2) do we need to consider in the alcoholic patient treatment?
- Wernicke’s encephalopathy may be there -> thiamine (B1 vitamin) deficiency
- treat alcohol withdrawal symptoms -> benzodiazepines
The classic triad of Wernicke’s encephalopathy
Wernicke’s encephalopathy: thiamine/vitamin B1 deficiency
Triad: ophthalmoplegia, ataxia, memory loss
Treatment for opioid overdose
Naloxone 200 mcg IV
The antidote for:
Tricarboxylic acid
Bicarbonate
Antidote for B-blockers
Glucagon
Antidote for iron
Desferrioxamine
Antidote for methanol, ethylene glycol
Glucagon
Antidote for Paracetamol
N-acetylcysteine
The antidote for Carbon monoxide
Oxygen
Antidote for Benzodiazepines
Flumazenil
Antidote for opiates
Naloxone
Do we give Flumazenil to the patient who comes with OD of unknown drugs?
Not if we do not know what pt has taken
Flumazenil - the antidote for benzodiazepines
BUT
- If we do not know what other meds they take, e.g. benzodiazepines for stopping seizures -> we may induce seizures
- In that case, we would not be able to stop the seizures as we would block benzodiazepines receptors
Some atypical presentation of SAH
- may have all signs of meningitis (hours/days)
- 3rd and 6th nerve palsy
- papilledema/ subhyaloid haemorrhage
Is SAH always +ive on CT scan?
Smaller bleeds may be -ve on CT -> check LP (xanthochromia)
What two scales are used to assess the severity of SAH?
Management of SAH
- BP management - enough to perfuse the brain but not too much to make bleeding worse
- Nimodipine - to prevent cerebellar vasospasm
How do we reduce ICP in acute situation? (2)
- Mannitol 0.5g/kg
OR
- Hypertonic saline
