GMC Problem #2 - COMA

Dr Robert Boots
Dr David Fraenkel
Department of Anaesthesiology and Intensive Care
Royal Brisbane Hospital

Questions to be answered.

1. Define Coma

2. What anatomical structures must be malfunctioning to produce coma?

3. What are the initial steps in managing a patient with coma?

4. How do you go about diagnosing the cause of coma?

5. Give pathological reasons for the following signs

purpuric rash

'Battle' sign

bilateral large fixed pupils

unilateral large fixed pupil

nuchal rigidity

gynaecomastia and spider naevi

bilateral pinpoint pupils

unilateral chemosis and proptosis

myoclonus

quadriplegia, loss of lower cranial nerve function but retained vertical eye movements

6. How dos the finding of a new focal abnormality on neurological examination affect the management of the comatose patient?

7. Does a nonfocal neurological examination in a comatose patient exclude a mass as the cause of coma?

8. What initial laboratory investigations should be performed in coma of uncertain aetiology?

9. What is the approach to the comatose trauma patient?

10. What are the common causes of coma in the ICU?

What is meant by the term 'COMA'?

Why is coma worth knowing about?

Integrates disease process, pathophysiology, and clinical presentation

Coma is a common presentation of severe illnesses

A normal level of consciousness (wakefulness) depends upon activation of the cerebral hemispheres by neurons located in the brainstem RAS. Both of these components and the connections between them must be preserved for normal consciousness to be maintained. The principal causes of coma are therefore: (1) widespread damage in both hemispheres from ischemia, trauma, or other less common brain diseases; (2) suppression of cerebral function by extrinsic drugs, toxins, or hypoxia or by internal metabolic derangements such as hypoglycemia, azotemia, hepatic failure, or hypercalcemia; and (3) brainstem lesions that cause proximate damage to the RAS.

 

Coma is diagnostically challenging

Differential Diagnosis of Coma

Pathological Site

Primary Cause

Secondary Cause

Location

INTRACRANIAL

Vascular

Haemorrhage

intracerebral

 

 

 

subarachnoid

 

 

 

subdural

 

 

 

extradural

 

 

Infarction

 

 

Infection

Meningitis

 

 

 

Encephalitis

 

 

 

Abscess

 

 

Tumour

Mass effect

 

 

 

Cerebral oedema

 

 

Post epileptic

 

 

 

Head injury

Vascular effects

 

 

 

Hypoxic encephalopathy

 

 

 

Cerebral oedema

 

 

Psychiatric

Conversion disorder

 

 

 

Depression

 

 

 

Catatonia

 

EXTRACRANIAL

Cardiovascular

Shock (any cause)

 

 

 

Severe hypertension

 

 

Infection

Septicaemia

 

 

Metabolic

Hyper/hypo-osmolar states

 

 

 

Hyper/hypoglycaemia

 

 

 

Hormonal insufficiency

Pituitary

 

 

 

Adrenal

 

 

 

Thyroid

 

 

Electrolyte disorders

 

 

 

Hypoxia

 

 

 

Carbon monoxide poisoning

 

 

 

Hypercarbia

 

 

 

Hepatic encephalopathy

 

 

 

Uraemic encephalopathy

 

 

Drugs

Sedatives

 

 

 

Analgesics

 

 

 

Alcohol

 

 

 

Major tranquillizers

 

 

Physical injury

Hyper/hypothermia

 

 

 

Electrocution

 

Therapeutics

Iatrogenic coma - must be evaluated and managed

Patients may present with a change in cerebration or cognitive processes

Clinical Assessment

Begin simply and accurately - then get specific

Initial Assessment

Approach to management

Appearance of patient

Interrogation - form and content of replies

History from third parties

Physical Examination

Brief Neurological Examination to determine level of consciousness

A  Alert

V  responds to Verbal stimuli

P  responds to Painful stimuli

U Unresponsive

Physical examination - Vital signs

Central Nervous System (CNS)

CNS assessment - Glascow Coma Score

 
Eye Opening                                                
                   Spontaneous                 4                  
                   To speech                   3                  
                   To pain                     2                  
                   Nil                         1                  
 
Best Motor Response                                                     
                   Obeys commands              6                  
                   Localises to pain           5                  
                   Withdraws to pain           4                  
                   Abnormal flexion            3                  
                   Extensor response           2                  
                   Nil                         1                  
 
Verbal Response                                            
                   Orientated                  5                  
                   Confused  conversation      4                   
                   Inappropriate words         3                  
                   Incomprehensible words      2                                                
                   nil                         1                 

Maximum possible 15 Minimum possible 3 Intubate if GCS < 10generally
The individual components are more important than the total number!

Approaches to Diagnosis - Clues

purpuric rash

meningococcemia

battle sign

base of skull fracture

bilateral large fixed pupils

atropine poisoning

unilateral large sluggish pupils

III nerve lesion temporal cone

mid position pupils no light response

midbrain lesion

nuchal rigidity

meningitis

gynaecomastia/spider naevi

hepatic encephalopathy

bilateral pinpoint reactive pupils

narcotic overdose

Horner's syndrome

medullary lesion

myoclonus

hypoxic encephalopathy

hyperventilation

brainstem (usually pulmonary)

Cheynes Stokes breathing

deep bilateral subcortical lesion

Apneustic breathing

pontine lesion

 

 

Approaches to Diagnosis-Clues

Fever
Hypothermia
Tachycardia
Bradycardia
Hypertension
Hypotension
Tachypnoea
Hypopnoea

Investigation

Approaches to Diagnosis-Laboratory Investigations

Treatment

General Management