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bài Glasgow Coma Scale

Glasgow Coma Scale
Past, Present, Future
KKH Morning Teaching - March 2013
Tan Hon Liang


Past: Background
 1940s




WWII: Medical Research Council, UK issued glossary of terms used in cases of head injury.
16 terms included coma, semi-coma, stupor, confusion, obtundation.
Tedious and not unified.


Past: Background
 Advent of Critical Care (1947 Polio outbreak)




Improved survival with resuscitation.



Need for uniform language to communicate patient status and for research

Intensivists wanted to know how to predict who was worth treating (or continuing to treat), and to assess the
relative value of alternative management


Past: Background
 In 1974


(Sir) Graham Teasdale (1940 - )






Knighted 2006

Bryan Jennett (1926-2008)






RCS President 2003-2006

Other fame: “Economy Class Syndrome”
Computerized database

Neurosurgeons in Glasgow


Lancet. 1974 Jul 13;2 (7872):81-4.


Assessment of coma
and impaired consciousness.
A practical scale.

Citation count: 7417


Past: Background
 Original 14 point scale intended to objectively determine the severity of brain dysfunction and coma six
hours after the occurrence of head trauma.



Why 6 hours?

 Subsequent revised in 1976 with the addition of a sixth point in the motor response subscale for
“withdrawal from painful stimulus”


Past: Background
 Accepted classification:




13-15 (mild HI)
9-12 (moderate HI)
< 8 (severe HI)


Past: Background
 World wide adoption contributed in no small part by nurses.
 Easy to chart.


Past: Background
 Numerical, easy to analyze.
 Since 1974, > 4000 articles published.




Added into other scores: APACHE, SAPS, TRISS, CRAMS, ASCOT.
Used to prognosticate.
Used to recommend treatment: WFNS for SAH, ATLS for intubation.

 Advocates and detractors.


Past: Background
 How about kids?


Past: Background
 Different total score proposed:




9 (at six months),
11 (at 1 year),
13-14 (at 5 years)

 Paediatric Glasgow Coma Scale


For adjust for milestones which have not been reached.


Past: Background
 EYE OPENING





Spontaneous (4) : indicative of activity of brainstem arousal mechanisms but not necessarily of attentiveness.
To speech (3) : tested by any verbal approach (spoken or shouted).
To pain (2) : tested by a stimulus in the limbs (supraorbital pressure may cause grimacing and eye closure).
None (1) : no response to speech or pain.


Past: Background
 EYE OPENING Limitations:





Vegetative States: Eyes may spontaneously open. “Lights on, but nobody at home”.
Noxious stimulus: grimace and eye closure. Then how?
Eye injury.
Drugs: muscle relaxants, sedation.


Past: Background
 BEST VERBAL RESPONSE






Oriented (5): awareness of the self and the environment (who / where / when).
Confused (4): responses to questions with presence of disorientation and confusion.
Inappropriate words (3): speech in a random way, no conversational exchange.
Incomprehensible sounds(2): moaning, groaning.
None (1): no response.


Past: Background
 BEST VERBAL RESPONSE Limitations:



Facial injury.
Focal neurological injury:









Broca’s aphasia
Wernicke’s aphasia
Conductive aphasia

Language.
Intubation, tracheostomy.
Drugs: muscle relaxants, sedation.


Past: Background
 BEST MOTOR RESPONSE





Obeying commands (6)



Extensor posturing (2): adduction and hyperpronation of upper extremities, extension of legs, plantar flexion of
feet, progress to opisthotonus (decerebration).



None (1)

Localizing (5): movement of limb as to attempt to remove the stimulus, the arm crosses midline.
Normal flexor response (4): rapid withdrawal and abduction of shoulder.
Abnormal flexor response(3): adduction of upper extremities, flexion of arms, wrists and fingers, extension and
internal rotation of lower extremities, plantar flexion of feet, and assumption of a hemiplegic or decorticate
posture.


Past: Background
 BEST MOTOR RESPONSE Limitations


M4-6: Must rule out grasp reflex or postural adjustment. Peripheral stimuli may elicit a spinal reflex response,
while pressure on the sternum or the supraorbital ridge may cause injury.





M3: implies that the lesion is located in the internal capsule or cerebral hemispheres
M2: score of 2 describes a midbrain to upper pontine damage
M1: must rule out an inadequate stimulus, spinal transection, limb injury/pain.


Past: Background
 Despite all that limitation, GCS continues to be widely adapted.
 Used to:





assess coma, monitor changes in coma,
as indicator of severity of illness
Triage patients with head injury in EMD/to ICU
aid in clinical decisions, such as intubation


Present: True or False
1. Glasgow Coma Scale is an accurate neurological assessment tool.
2. GCS predicts outcome.
3. GCS < 9: I should intubate the patient.




If I don’t, the patient will aspirate/die.
Other than trauma, I can use GCS for





Poisoning,
Stroke,
Sepsis.


1. Glasgow Coma Scale is an accurate neurological
assessment tool?
 Effects of resuscitation



Benzodiazepine, induction drugs, muscle relaxants, intubation, eye trauma, ear injury.
GCS 3 performs better than GCS 4

 Less than 4% of patients die without opening eyes. Arousal does not mean awareness.


Hence does not accurate reflect extent of neurological dysfunction.


Fourth level
Fifth level

GCS has observer bias.
- Observations may not be standardized.
- Errors up to 2 points.


2. Glasgow Coma Scale can predict outcome?
 A number of studies show correlation.
 But a number also show no correlation.


2. Glasgow Coma Scale can predict outcome?
 Bruechler et al (1998) contacted 73 Level I trauma centers and questioned them about GCS scoring in
case of intubation.





26% of the trauma centers gave 1 point for verbal component,




replacing missing values with an average value of the testable score (Meredith et al., 1998)

23% 3 points,
16% assigned a “T” for verbal component.

 Other studies mention the pseudoscoring technique
or assigning a score of 5 if patients seem able to talk, of 3 if there is questionable ability to talk and of 1 if
patients are generally unresponsive (Rutledge et al., 1996).


Third level
Fourth level
Fifth level

As a result, a lot of research cannot be reliably intepreted.
Or trusted.


2. Glasgow Coma Scale can predict outcome?
 The GCS is an ordinal scale.



The difference between unit values is not consistent and compares only better with worse
Yet, minimal differences of GCS scores are important in terms of prognosis.

 The scale incorporates a numerical skew towards motor response, because there are only 4 points for
eye response, versus 5 for verbal and 6 for motor responses.



Summing the three sub- scales assumes an equal weighting for each one, thus leading to loss of information
since the same score can be made up in various ways


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