Case 9.1 – Asthma (ED)

In approaching the critically ill child, the diagnosis is of secondary importance to:

• Primary assessment, which is a structured activity, and
• Timely resuscitation procedures

The primary assessment follows progression through the following A, B, C, D, E steps:

• Airway
• Breathing
• Circulation
• Disability (deficiency of cerebral function)
• Exposure

This structured approach is based on the knowledge that the brain requires a continual supply of oxygen and glucose. An airway problem will rapidly lead to death and must be corrected first.

Airway

Anatomical considerations in children:

• Infants are obligate nose-breathers
• Smaller airways and mandible
• Proportionately larger tongue and more floppy epiglottis and soft palate
• Narrowest portion is below the cords at the cricoid ring (vs. vocal cords in adults)
• Short, soft trachea - hyperextension or flexion may cause obstruction

Assessment - Look, Listen, Feel:

• Look: Chest wall and abdominal movement, intercostal and accessory muscle use, paradoxical abdominal movement with upper airway obstruction
• Listen: Air movement over mouth/nose, inspiratory stridor (tracheal/laryngeal/upper airway obstruction), auscultate over trachea and axillae
• Feel: Place face close to child's mouth to feel air movement

Breathing

Important differences in children:

• Higher metabolic requirement
• More immature musculature with easy diaphragmatic fatigability
• More compliant chest wall with more horizontal ribs, decreasing bellows efficiency
• Proportionately smaller airways - resistance inversely proportional to 4th power of radius

Assessment divided into three aspects:

1. Effort of breathing:

• Respiratory rate (age-dependent) - tachypnoea is early response
• Increased depth of respiration as failure progresses
• Intercostal and subcostal recession
• Sternal retraction in infants
• Sternomastoid muscle recruitment
• Nasal flaring (late sign in infants/small children)

Note: Diminished effort occurs in three circumstances:

• Exhaustion from increased respiratory demands
• Depressed central respiratory drive (trauma, meningitis, poisoning)
• Neuromuscular paralysis (muscular dystrophy, Guillain-Barré)

2. Efficacy of breathing:

• Confirm symmetrical chest movement
• Watch for abdominal movement (diaphragm is main respiratory muscle in young children)
• Auscultate both sides - beware the silent chest!
• Note wheezing (lower airway narrowing with prolonged expiratory phase)
• Note crepitations (pneumonia, heart failure)
• Oximetry for SaO₂ (may be difficult in cold/shocked child)

3. Effects on other organs:

• Cardiovascular: Tachycardia (bradycardia is preterminal), peripheral shutdown, pallor
• Brain: Initial agitation/irritability in infants, followed by loss of consciousness
• Note: Cyanosis is a preterminal sign

Circulation

Physiological considerations:

• Cardiac output = stroke volume × heart rate
• Infants have small, relatively fixed stroke volume - must increase heart rate to respond to increased demand
• Relatively larger intravascular volume (85 ml/kg in infants, decreases to 60 ml/kg in teenagers)
• Blood pressure increases with age

Assessment:

• Heart rate increase is earliest response to reduced intravascular volume (bradycardia is preterminal)
• Assess pulse volume peripherally and centrally - weak central pulses indicate severe shock
• Capillary refill: Apply pressure to sternum for 5 seconds - normal refill <3 seconds (caution in cold environment)
• Hypotension is a late preterminal sign

Effects on other organs:

• Poor tissue perfusion → metabolic acidosis → compensatory tachypnoea
• Initial agitation from sympathetic stimulation, later drowsiness/coma
• Prerenal failure with reduced urine output (normal: >1 ml/kg/h in child, >2 ml/kg/h in infant)

Signs of cardiac failure:

• Raised JVP (difficult in young children)
• Gallop rhythm
• Lung crepitations
• Hepatomegaly

Disability

Three main aims:

• Rapidly determine level of consciousness
• Find localising intracranial lesions
• Determine if raised intracranial pressure

Important: Respiratory and cardiovascular failure can cause decreased consciousness and must be dealt with first.

Conscious level - AVPU method:

• A Alert
• V responds to Voice
• P responds to Pain
• U Unresponsive

Note: Unresponsive or only responds to pain = GCS ≤8

Posture and tone:

• Hypotonia in seriously ill child
• Decorticate posturing: flexed upper limbs, extended lower limbs (preterminal)
• Decerebrate posturing: extended upper and lower limbs (preterminal)

Pupil examination:

• Unequal pupils may indicate tentorial herniation or rapidly expanding lesion
• Small reactive pupils suggest metabolic disorder or medullary lesion

Respiratory patterns in neurological failure:

• Raised ICP can cause abnormal breathing patterns from hyperventilation to apnoea
• Cushing triad (late signs of raised ICP): Hypertension, bradycardia, hypoventilation
• Hypotension is preterminal

Exposure

• Infants/small children have proportionately greater surface area - lose heat more rapidly
• Infants less able to respond to hypothermia
• Measure core temperature early
• Maintain appropriate warming during resuscitation
• Fever may indicate infection
• Fully expose child to look for valuable clues (rashes, bruises) but do sensitively

Reassessment

Frequent reassessment should be undertaken, especially if deterioration occurs during resuscitation. Search for definitive diagnosis after stabilisation.

Key Practical Points:

• In collapsed child, careful primary assessment and timely resuscitation are more important than diagnosis
• Children differ physiologically and anatomically from adults
• Respiratory conditions are common pathway to collapse in children
• Cyanosis and hypotension are preterminal signs
• Decerebrate and decorticate posturing are preterminal signs

Causes of Paediatric Emergencies

Airway	Breathing	Circulation	Disability	Exposure
Croup Epiglottitis Laryngeal foreign body Bacterial tracheitis Trauma Angioneurotic oedema Retropharyngeal abscess	Asthma Bronchiolitis Pneumonia Foreign body Congestive heart failure Neuromuscular diseases Trauma: Pneumothorax Haemothorax Lung contusion Flail chest Near drowning Smoke inhalation Metabolic acidosis: Diabetic ketoacidosis Poisoning: Salicylates Methanol	Congenital heart disease Duct dependent lesions: Critical aortic stenosis Hypoplastic left heart Coarctation Dysrhythmias: Bradycardia Tachycardia (Supraventricular/Ventricular) Torsade de pointes Fibrillation Pulseless electrical activity Shock: Cardiogenic: Cardiomyopathy, Heart failure, Myocardial contusion Hypovolaemic: Haemorrhage, Vomiting/diarrhoea, Burns Distributive: Septicaemia, Anaphylaxis, Spinal cord injury Obstructive: Cardiac tamponade, Hypertension Dissociative	Seizure Meningitis Encephalitis Head injury Raised intracranial pressure Hypoglycaemia Metabolic disorder Poisoning Envenomation	Hypothermia Hyperthermia Inflicted injury

Vital Signs by Age

Age (years)	Respiratory Rate (breaths/min)	Heart Rate (beats/min)	Systolic Blood Pressure (mmHg)
<1	30-40	110-160	70-90
1-2	25-35	100-150	80-95
2-5	25-30	95-140	80-100
5-12	20-25	80-120	90-110
>12	15-20	60-100	100-120

Causes of Collapse in Children

Category	Diagnosis
Primary neurological process	Meningitis Head injury Encephalitis Seizures
Failure of oxygen supply to brain	Acute asphyxia (e.g. drowning, birth asphyxia) Respiratory causes (e.g. severe asthma, croup) Cardiac causes (e.g. arrhythmias, myocarditis) Hypovolaemia (e.g. dehydration, haemorrhage) Sepsis Anaphylaxis
Metabolic disturbance or toxins	Hypoglycaemia Hyponatraemia Drug or other toxic ingestion Envenomation Bacterial toxins

Principles of Resuscitation in Children

The general principles of resuscitation might be the same as used in adults, but specific techniques are required in children.

Primary Aim: To restore an adequate supply of oxygenated blood to the brain to prevent secondary brain damage.

Resuscitation procedures vary depending on degree of physiological impairment:

• Simple measures: Application of oxygen facemask, administration of IV fluid bolus
• Basic cardiopulmonary resuscitation
• Advanced life support measures: Endotracheal intubation, mechanical ventilation, vasoactive drugs

Key Practical Points

• Do not waste time assessing adequacy of breathing and circulation in a collapsed child - assessment can be misleading and time-consuming
• If circulation or breathing are inadequate or uncertain, administer cardiac compressions and artificial respiration
• Never hesitate to give a trial of IV fluid bolus to a collapsed child
• Learn the technique of intraosseous needle placement - this simple technique can be life-saving
• Call for extra assistance early

Advanced Life Support Algorithm

Continuous CPR Pre-intubation:

• ~100 compressions/minute
• 15 compressions then 2 breaths
• Pause compressions for each breath

Simultaneously (if enough staff available):

• Intubate and ventilate (only pause CPR briefly for intubation)
• Attach monitor/defibrillator
• Obtain IV or IO access

Post-intubation CPR:

• ~100 compressions/minute
• ~10 breaths/minute
• Do not pause compressions for breaths

Rhythm Assessment (maximum 10 seconds)

SHOCKABLE (VF or pulseless VT):

1. One DC Shock
   • 2 J/kg 1st cycle
   • 4 J/kg subsequent cycles
2. Immediately resume CPR for 2 minutes
3. Adrenaline 10mcg/kg - for 3rd and subsequent cycles
4. Reassess rhythm

NON-SHOCKABLE (Asystole or Pulseless Electrical Activity):

1. Adrenaline 10mcg/kg immediately
2. Resume CPR for 2 minutes
3. Reassess rhythm

Continue cycles of CPR with rhythm assessment every 2 minutes

Basic Life Support

1. Check if patient responds to command/pain
2. Call for help
3. Position patient
   • Check airway: Ensure airway patent
4. Check breathing:
   • If inadequate, or if any doubt:
   • Give assisted respiration
   • Use Bag & Mask with oxygen if available
   • Check chest moves with each breath
5. Check pulse:
   • If absent, too slow, or weak, or if any doubt:
   • Give cardiac compressions
   • ~100 compressions/minute
   • 15 compressions then 2 breaths
   • Pause compressions for each breath if patient not intubated
6. Move to advanced life support when possible

Advanced Life Support - Key Points

Critical Actions:

• Do not waste time assessing adequacy of breathing and circulation in collapsed child - can be misleading and time-consuming
• If circulation or breathing inadequate or uncertain, administer cardiac compressions and artificial respiration
• Never hesitate to give trial of IV fluid bolus to collapsed child
• Learn intraosseous needle placement - life-saving technique
• Call for extra assistance early

Rhythm Management:

• Shockable rhythms (VF/pulseless VT): DC shock → CPR 2 min → reassess
• Non-shockable rhythms (Asystole/PEA): Adrenaline → CPR 2 min → reassess
• Adrenaline dose: 10mcg/kg
• Shock energy: 2 J/kg (1st), 4 J/kg (subsequent)