glasgow coma scale - past present future

Glasgow Coma ScalePast, 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.

Intensivists wanted to know how to predict who was worth

treating (or continuing to treat), and to assess the relative value

of alternative management

Need for uniform language to communicate patient status and

for research

Past: Background In 1974

(Sir) Graham Teasdale (1940 - )

RCS President 2003-2006

Knighted 2006

Bryan Jennett (1926-2008)

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)

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.

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

None (1)

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 False1. 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.

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,

23% 3 points,

16% assigned a “T” for verbal component.

Other studies mention the pseudoscoring technique

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

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).

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

2. Glasgow Coma Scale can

predict outcome? GCS: collection of 120 mathematical combinations

eighteen possible permutations exist for total GCS score of 9

seventeen for scores 8 and 10

fourteen for scores 7 and 11

ten for scores 6 and 12

Therefore, not all GCS 9 are equal.

How can one prognosticate outcome if not all that seems are

equal?

3. GCS and Intubation GCS < 9 = Intubate

Clinical Case 1 You are the Anaesthetic On Call.

You are called to the Emergency Department to assist in the

airway management of a 14 year old female, A.

Clinical Case 1 You are informed that this child was found by her parents

drowsy at home in bed with 2 empty can of beer and 1 empty

750 ml bottle of wine.

You assess the patient…

Clinical Case 1 Eyes do not open to stimulus.

Speech is incoherent and slurred.

There is flexion of her upper limbs to stimulus.

Clinical Case 1 What do you do next?

Do you intubate this patient?

Clinical Case 2 You are the Anaesthetic On Call.

You are called to the Emergency Department to assist in the

airway management of a 14 year old female, B.

Clinical Case 2 You are informed that this child was found by her parents

drowsy at home in bed.

She is known to have epilepsy.

You assess the patient…

Clinical Case 2 Eyes do not open to stimulus.

Speech is incoherent and slurred.

There is flexion of her upper limbs to stimulus.

Clinical Case 2 What do you do next?

Do you intubate this patient?

Advocates On the basis of recommendations from

the American College of Surgeons Committee on Trauma,

the European Society of Intensive Care Medicine and

the Eastern Association for the Surgery of Trauma,

GCS <9 is used as the level at which intubation is considered

mandatory.

One paper that ruled them all….

Advocates Rationale:

Hypoxemia is bad for the injured brain.

Tracheal intubation is the surest way of delivering oxygen.

Therefore, intubation is mandatory.

(How about just providing oxygen with jaw thrust??)

Additional benefit of preventing aspiration.

(Chances are it would already have occurred)

3. GCS < 9 does not mandate

intubation Not all GCS < 9 are equal.

GCS scoring wise, we seen that.

Not to be extrapolated to all forms of depressed neurology.

Trauma is different from poisoning, stroke, sepsis.

Not all GCS < 9 lose gag/cough reflex.

Not all who loses gag/cough reflex aspirates.

Association with respiratory insufficiency but no association

between a particular GCS and impaired pharyngeal control!

GCS < 9 does not mandate intubation

Considerable proportion of patients with low GCS had

gag/cough.

Many patients with GCS>8 had impaired airway reflexes.

So GCS <9 trigger is flawed.

GCS < 9 does not mandate intubation

All GCS < 9 non trauma EMD patients included:

557 patients. 129 tubed for cardiac arrest, resp failure, severe stroke.

428 not tubed: 364 (85%) regained consciousness,

64 remained unconscious – 12 of these needed to be tubed

GCS < 9 does not mandate intubation

GCS < 9 does not mandate intubation

Drug or alcohol intoxication: 73 patients

12 GCS <9 but none required intubation or

aspirated.

1 patient intubated: GCS 12 on presentation!

Clinical Cases Case 1: intoxicated A

Tube?

Case 2: post ictal B

Tube?

The Future? GCS

Past has been glorious.

Present is murky.

Future is uncertain.

My Conclusion GCS:

It’s for Head Injury. Be careful extrapolating beyond what it is

meant to do.

After 6 hours.

For communication

For standardized classification/research.

Useful for trending, but beware observer error. Drop in 2 points

probably good trigger for reassessment.

No magic number for intubation

<9 doesn’t always mean tube, while >/= 9 does means it is safe.

tan.hon.liang@sgh.com.sg