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Coma

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Definition

A state of unrousability. The changes in mental state which precede coma may be classified by the "Modified Glasgow Coma Scale For Infants And Young Children"
 
In this scale, the total score = eye opening + motor response + verbal response. The best response is scored. The lowest score is 3, and the highest is 15 (the fully conscious child). Children in coma have GCS scores of 8 or less. In the context of head trauma, a GCS of 8 or less suggests severe cerebral injury, a GCS of 9 - 12 moderate cerebral injury, and a GCS of 13 - 15 minor cerebral injury.
 
Limitations of the GCS include the fact that the verbal component is difficult to apply to young children and cannot be applied to the intubated patient. The score does not give any weight to focal deficits such as hemiparesis. The score was developed in adults, and does not have the same predictive value in childhood.

Category Score  Response < 1 year  Response > 1 year 
Eye opening  4
3
2
1
spontaneous
to shout
to pain
none
spontaneous
to speech
to pain
none
Best motor response 6
5
4
3
2
1

normal movement
localizes pain
flexion withdrawal 1
flexion - abnormal (decorticate)
extension (decerebrate)
none

obeys command
localizes pain
flexion withdrawal
flexion - abnormal (decorticate)
extension (decerebrate)
none
    0 - 23 months 2 - 5 years  > 5 years 
Best verbal response2 5
4
3
2
1
smiles / coos / cries appropriate
cries / screams consolable
irritable / inconsolable
grunts / agitated
none
appropriate words / phrases
inappropriate words
cries / screams
grunts
none
orientated
confused response
inappropriate words
incomprehensible
none

1   apply knuckles to sternum and observe arms
2   arouse patient with painful stimulus if necessary

Causes 

Cerebral hypoxaemia/ ischaemia Severe anaemia, apnoea, asphyxiation, carbon monoxide poisoning, drowning, respiratory failure, shock (adrenal crisis, cardiogenic, septic, hypovolaemic), cerebrovascular event. 
Epilepsy Post-ictal state, status epilepticus 
Infectious diseases Encephalitis, meningitis, septic shock 
Raised intracranial  Mass lesions (abscess, empyema, haemorrhage or pressure tumour), cerebral oedema, hydrocephalus, malfunction of a ventriculo-peritoneal shunt 
Metabolic and endocrine disorders  Diabetic ketoacidosis, hypoglycaemia, hypernatraemia, hyponatraemia, hypocalcaemia, hypomagnesaemia, liver failure, renal failure (uremia), inborn errors of metabolism 
Toxic  Substance abuse (alcohol, hallucinogens, opiates, volatile agents), clonidine, paracetamol, prescription drugs, salicylates, lead, other 
Trauma  Concussion, cerebral contusion, intracranial haemorrhage, cerebral oedema (remember shaken infant syndrome)
Other  Acute confusional migraine, psychiatric 

History  

  • Time-course of changes in mental state (behavior, feeding, schoolwork)
  • Past and recent medical history (including medications)
  • Family history (for example, of epilepsy or migraine)
  • Drugs or toxins present in the house
  • History of head trauma.

Examination  

Do not assess for meningeal irritation unless cervical spine trauma is unlikely or has been excluded. A complete physical examination is essential. Do not forget:

Cardiovascular Blood pressure, pulse rate and rhythm, peripheral perfusion 
Neurological  Posture, evidence of a ventricular shunt, level of consciousness, localising signs, pupillary responses, examination of the fundi, signs of trauma to the head 
Respiration  Colour (cyanosis), rate and pattern of breathing 
Skin  Abnormal pigmentation, anaemia, bruising, jaundice, needle marks, petechiae, sweating 
Smell  Alcohol, glue, ketones, "bitter almonds" (cyanide), phenol 
Temperature  Hypothermia or hyperpyrexia 

Suspect raised ICP if there is a GCS score < 9; abnormal vital signs (hypertension, bradycardia, abnormal respiratory pattern); fixed dilated pupils; decerebrate / decorticate posturing; or status epilepticus unresponsive to standard therapy (see Emergency Management of Raised ICP).

Where is the Lesion?  

It is difficult to differentiate supratentorial from infratentorial lesions unless localising brainstem signs precede the onset of coma.

Supratentorial Focal hemispheric signs, progression of signs from head to foot, Cheynes-Stokes respiration (diencephalon: hyperpnoea alternating with apnoea), decorticate posture (arm flexion and leg extension), unilateral pupil constriction and a Horner syndrome (hypothalamus), unilateral fixed dilated pupil (temporal lobe herniation) 
Infratentorial  Dilated pupils with poor response to light (if no mydriatic given), midposition fixed pupils (midbrain), small reactive pupils (pons), Horner syndrome (lateral medullary lesions), abnormal respiratory pattern, cranial nerve palsies, negative ice water caloric test / doll's eye, decerebrate rigidity (generalised extension of trunk and limbs) 
Metabolic Changes in mental state precede motor signs, motor signs are symmetrical, pupillary reactions are preserved, disturbed acid-base is common, seizures or abnormal motor movements are common 
Toxic  Pinpoint pupils (narcotics, barbiturates, some mushrooms, organo-phosphates, phencyclidine), Dilated ± unresponsive pupils (atropine, amphetamine, calcium channel blockers, cocaine, cyanide, digoxin, ergotamine, ethanol, LSD, neuroleptics, tricyclic antidepressants) 

Management 

Airway Protect and maintain. Use airway adjunct (oropharyngeal, nasopharyngeal, LMA) or intubate if unable to maintain airway.
If GCS < 9 and clinical circumstances do not suggest improvement imminent then intubation is indicated to secure airway. 
Breathing  Give oxygen until saturations known, monitor O2 saturation, assess rate and pattern of breathing. Support breathing by hand bagging if required.
Supplemental oxygen is indicated for hypoxia, but should not be given routinely to comatose children with normal circulation & oxygen saturation. 
Circulation  Obtain venous access. Assess for signs of shock and treat as indicated (see guidelines on shock)
The aim of fluid therapy in raised ICP is to maintain adequate cerebral perfusion pressure (CPP).

CPP = Mean arterial pressure - Intracranial pressure

Resuscitation of the circulation takes priority over fluid restriction & osmotic therapy.  These treatments should not be commenced until after adequate fluid resuscitation to restore a perfusing blood pressure
Dextrose  Aim to avoid both hyper and hypoglycaemia
Check blood glucose level. If low, take blood for hormones (insulin, hGH, cortisol) and ketones and give a bolus of 10% Dextrose 5 ml/kg IV, followed by a 10% Dextrose infusion at 4 ml/kg/hour (7 mg/kg/min) with close monitoring of glucose.
If high, consider diabetes 
Drugs  If opiates suspected, consider Naloxone 0.1-0.8 milligrams/kg IV (maximum dose 2 milligrams) - particularly if respiratory depression.
Avoid Flumazenil, which may induce convulsions in mixed overdoses, particularly if tricyclic antidepressants have been taken.  Isolated benzodiazepine overdose does not cause significant respiratory depression and children are best managed with simple observation. If you decide to use Flumazenil, the dose is 5 micrograms/kg IV. You can repeat this every minute to a total of 40 micrograms/kg (maximum dose 2 milligrams) 
Specific therapy  After stabilisation a rapid approach to diagnosis is imperative so that specific therapy can be given. See guidelines for the management of poisoning and specific conditions, and consult the National Poisons Centre for specific toxins
Acyclovir and cefotaxime should be administered acutely if encephalitis or meningitis is a possibility. 

Emergency Management of Raised Intracranial Pressure 

i.e. GCS < 9 and Cushing's triad of hypertension, bradycardia, abnormal respiration (gasping, irregular, sporadic) and / or fixed, dilated pupil(s)

Airway Oxygenate and intubate
Ventilate  Avoid hypercapnoea, aim to maintain a pC02 of 4.5 to 5.0 kPa  
Osmotic therapy  Use 3% NaCl - give 3 ml/kg IV given as a rapid infusion (e.g. over 5 to 10 minutes)
or
Use Mannitol - 0.5g to 1.0g/kg (2.5 to 5ml/kg of 20% Mannitol)
Will need to place a urinary catheter
Sedation and pain relief  For example morphine and midazolam 
Elevate head  To 30° 
Control fever  Give Paracetamol intragastrically or rectally 10 -15mg/kg q 4 hrly 

Further Investigations

FBC Consider coagulation screen 
Glucose  If hypoglycaemic measure insulin, blood ketones, growth hormone and cortisol
A laboratory or blood gas analyser glucose is required for confirmation of the bedside testing result, but do not delay treatment of symptomatic hypoglycaemia awaiting this result. 
Urea & electrolytes   
Blood Gas   
Urinalysis  Consider toxicology screen of urine and blood 
Liver function tests  Consider serum ammonia 
CT Head  +/- contrast (discuss with Radiology) 
Lumbar puncture  Contra-indicated in presence of coma (GCS <9), raised intra-cranial pressure or unstable clinical state. If meningitis is suspected but LP is contra-indicated, start antibiotics 
Cervical spine imaging  Protect neck until injury has been excluded by standard criteria in cases of trauma or possible trauma.  It is often not possible to exclude cervical spine injury in a comatose child.
May need to CT upper cervical spine in trauma 

Criteria for Admission to PICU

  • Inadequate airway protection
  • Unstable vital signs
  • Respiratory compromise:
    - irregular pattern of breathing
    - hypoxaemia
    - hypercarbia
  • Glasgow Coma Scale ≤13
    The Coma Score must be taken in the context of the possible diagnosis. A child with a GCS of 13 who is post-ictal after a febrile seizure would be regarded differently from a child whose GCS is falling 4 hours after a head injury.

PICU should be involved early for a child who clearly meets these criteria.  A child requiring a CT scan and admission to PICU should be transferred and monitored in CT by the PICU team.  Responsibility for children not requiring PICU admission will by the CED team with anaesthetist involvement as required for CT, and subsequent referral as appropriate.

A child who needs ongoing circulatory or respiratory resuscitation should not be transferred from CED to anywhere other than PICU or the operating theatres - they should not be moved to CT.

References 

Avner JR. Altered States of Consciousness. Peds in Rev 2006;27:331-337.

Kirkham FJ. Non-traumatic coma in children. Arch Dis Child 2001;85;303-312.

Wong CP, Forsyth RJ, Kelly TP, Eyre JA. Incidence, aetiology, and outcome of non-traumatic coma: a population based study. Arch Dis Child 2001;84;193-199.

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Document Control

  • Date last published: 01 August 2007
  • Document type: Clinical Guideline
  • Services responsible: Paediatric Intensive Care Unit, Children’s Emergency Department
  • Author(s): Mike Shepherd, Liz Segedin, Richard Aickin
  • Editor: Greg Williams
  • Review frequency: 2 years

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