Distinguishing vasovagal episodes from anaphylaxis reactions following immunisation
Immunisation providers must be able to distinguish between a vasovagal episode (fainting), convulsions and anaphylaxis.
Vasovagal episode (fainting) is relatively common after the vaccination of adults and adolescents, but infants and children rarely faint. Anaphylaxis following routine vaccination is very rare, but can be fatal.
Sudden loss of consciousness in young children should be presumed to be an anaphylaxis, particularly if a strong central pulse is absent. A strong central pulse (for example, carotid) persists during a vasovagal episode or convulsion.
For a printable version, download the Vasovagal episode or Anaphylaxis chart (PDF 62KB).
|Onset||Immediate, usually within minutes of or during receiving the vaccine||Usually within 15 minutes but can occur within hours of receiving the vaccine|
|Skin||Generalised pallor, cool clammy skin||
|Respiratory||Normal respiration, may be shallow but not laboured||
|Neurological||Feels faint, light-headed||Sense of severe anxiety and distress|
|Gastrointestinal||Nausea, vomiting||Abdominal cramps, diarrhoea, nausea and /or vomiting|
Management of anaphylaxis
Rapid IM administration of adrenaline is the foundation for treatment of anaphylaxis.
- If patient unconscious, place on left side and maintain airway
- if patient conscious, place in supine position, elevate legs (unless results in breathing difficulties)
- if showing signs of anaphylaxis give adrenaline by deep IM injection into the anterolateral thigh. Must not be given intravenously
- dial 000 and ask for an ambulance. Never leave patient alone
- administer O2 by facemask at a high flow rate, if available
- if no improvement in patient’s condition within 5 minutes, repeat doses of adrenaline every 5 minutes until condition improves or medical assistance arrives
- check breathing, if absent, commence basic life support or appropriate CPR as per the Australian Resuscitation guideline.
- transfer to hospital for further observation and/or treatment
- document the event including time(s) and dose(s) of adrenaline administration.
Adrenaline 1:1000 = 0.01 ml/kg (0.01mg/kg) deep IM injection in thigh
Less than 1 year (approx. 5-10 kg) 0.05 to 0.1mL
1 to 2 years (approx 10 kg) 0.1 mL
2 to 3 years (approx 15 kg) 0.15 mL
4 to 6 years (approx 20 kg) 0.2 mL
7 to 10 years (approx 30 kg) 0.3 mL
10 to 12 years (approx 40 kg) 0.4 mL
greater than 12 years and adult (over 50kg) 0.5 mL
use a 1 mL syringe to accurately measure the dose