Quick Chart
  • Asthma is characterised by hyper-reactive airways and inflammation leading to episodic, reversible bronchoconstriction in response to a variety of stimuli.

Read the complete article; Asthma in the Medical Library > Pathophysiology.

Clinical Presentation


  • Respiratory distress
  • Expiratory wheeze
  • Hyperinflated chest
  • Pulsus paradoxus in severe attacks
  • Silent chest


  • Cough
  • Shortness of breath and/or rapid respiration
  • Recession; sternal, intercostal, subcostal, suprasternal-tracheal tug
  • Nasal flaring
  • Accessory muscle use
  • Wheeze
  • Difficulty speaking
  • Pallor, cyanosis and exhaustion (late and preterminal signs)
Exclusion Criteria
Exclusion Criteria
Risk Assessment

Clinical Severity:

Mild / Moderate
  • Can walk, speak whole sentences in one breath
  • Oxygen saturation >94%
  • Wheeze might be evident
  • Use of accessory muscles of neck, intercostal muscles, or presence of 'tracheal tug' during inspiration or subcostal recession (i.e., abdominal breathing)
  • Unable to complete sentences in one breath due to dyspnoea
  • Obvious respiratory distress
  • Oxygen saturation 90–94%
  • Audible wheezing
  • Reduced consciousness or collapse
  • Exhaustion
  • Cyanosis
  • Oxygen saturation <90%
  • Poor respiratory effort, soft/absent breath sounds

The presence of any one of the following suggests the need for immediate transport and consideration of time criticality:
  • Prior ICU admission
  • Prior intubation
  • >3 ED visits in past year
  • >2 hospital admissions in past year
  • >1 bronchodilator canister used in past month
  • Use of bronchodilators > every 4 hours
  • Chronic use of steroids
  • Progressive symptoms in spite of aggressive treatment.
  • Patient unable to speak in sentences.

  • If doubt exists as to whether patient is experiencing asthma or anaphylaxis, treat as per Anaphylaxis CPG.
  • SpO2 is not a reliable isolated indicator of severity; a patient with a normal SpO2 reading can still be regarded as time critical due to carbon dioxide (CO2) retention.
  • Asthma is less likely to be the cause of wheezing in infants less than 12 months old.
  • If symptoms do not respond to treatment, reconsider the diagnosis.
Primary Care
  • Primary Survey
  • Position patient appropriately (sitting patient upright or in a position of comfort)
  • Conduct Vital Sign Survey, particularly respiratory rate and pulse oximetry
  • Consider oxygen therapy; titrate SpO2 using the appropriate mask to a target of 92–95% for adults and at ≥ 95% for children
  • Ventilate the patient if required:
    • Extreme care should be taken when ventilating an asthmatic patient; gently and at a rate of no more than 4-6 breaths per minute. This allows for adequate exhalation and avoids air trapping which may otherwise lead to reduced blood pressure and cardiac arrest
  • Officers may assist the patient in the administration of their own medication where clinically indicated
  • Be alert for rapid deterioration
Intermediate Care (EMT / Level 2)
  • If wheeze present, administer Salbutamol as per CPG
  • Consider applying cardiac monitor if trained and authorised
  • Monitor patient persistently, recording full observations every 10 minutes (or 5 minutes if time critical)
  • Transport Priority 1 if patient time critical, pre-notifying receiving facility
Advanced Care (AP)
Critical & Extended Care (CCP, PSO)
  • As per Advanced Care (AP) guidelines
Additional Information

Unresolved status asthmaticus can lead to:

  • Respiratory arrest
  • Cardiac arrest

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