Anaphylaxis Anaphylactic reactions

T78.2

DESCRIPTION

An acute, potentially life-threatening hypersensitivity reaction starting within seconds to minutes after administration of, or exposure to, a substance to which the individual is sensitised. Clinical manifestations include at least one of the following: upper airway obstruction, bronchospasm, hypotension, or shock.

The reaction can be short-lived, protracted or biphasic, i.e. acute with recurrence several hours later. Immediate reactions are usually the most severe.

DIAGNOSTIC CRITERIA

Clinical

  • Acute onset of signs and symptoms.
  • Dizziness, paraesthesia, syncope, sweating, flushing, dysrhythmias.
  • Swelling of eyes, lips and tongue (angioedema).
  • Upper airway obstruction with stridor.
  • Hypotension and shock.
  • Bronchospasm, wheezing, dyspnoea, chest tightness.
  • Gastrointestinal symptoms such as nausea, vomiting, diarrhoea.

A life-threatening anaphylactic reaction requires IMMEDIATE treatment.

Facilities to initiate treatment must be available at all health centres .

GENERAL AND SUPPORTIVE MEASURES

  • Place hypotensive or shocked patient in horizontal position. Do not place in a sitting position.
  • Assess and secure airway. If necessary, bag via mask or intubate.

MEDICINE TREATMENT

To maintain arterial oxygen saturation ≥95%:

  • Oxygen, 100%, at least 1–2 L/minute by nasal prong.

In severe anaphylaxis nasal oxygen is unlikely to be adequate:

  • Oxygen, 100%, 15 L/minute by face mask.
  • Epinephrine (adrenaline) 1:1 000 (undiluted), IM, 0.01 mL/kg. (i.e. 10 mcg/kg).
    • Can be repeated every 5 minutes, if necessary.
    • Maximum per dose: 0.5 mL.
    • Do not administer IV unless there is failure to respond to several doses of IM.

Crystalloid solutions e.g.:

  • Sodium chloride 0.9%, IV, 20 mL/kg rapidly.
    • Repeat if necessary until circulation, tissue perfusion and blood pressure improve (up to 60 mL/kg).
  • Promethazine, IV/IM, 0.25–0.5 mg/kg/dose. Contra-indicated in children <2 years old.

Then continue with:

  • Chlorphenamine, oral, 0.1 mg/kg/dose 6 hourly for 24–48 hours, if necessary.

If associated bronchospasm:

  • Salbutamol, nebulised, 1 mL salbutamol respirator solution in 3 mL sodium chloride 0.9%.
    • Nebulise at 20 minute intervals.
  • Hydrocortisone, IV, 5 mg/kg, 4–6 hourly for 12–24 hours.
    • Note: Steroids are adjunctive therapy, are not part of first line treatment, and should never be the sole treatment of anaphylaxis.

If associated stridor:

  • Epinephrine (adrenaline), 1:1000, nebulise with oxygen, every 15–30 minutes until expiratory obstruction is abolished.
    • 1 mL epinephrine 1:1 000 diluted in 1 mL sodium chloride 0.9%.

Observe for 24 hours, in particular for recurrent symptoms as part of a ‘biphasic’ reaction.

PREVENTATIVE MEASURES AND HOME BASED TREATMENT

  • Obtain a history of allergies/anaphylaxis on all patients before administering medication/immunisation.
  • Identify offending agent and avoid further exposure.
  • Ensure patient wears allergy identification disc/bracelet.
  • Train patients to self-administer epinephrine pre-filled auto injecting device. Specialist initiated for patients who have anaphylactic reactions.
  • Educate patient and parent/caregiver on allergy and anaphylaxis.

REFERRAL

Caution

Do not refer the patient during the acute phase. Transfer can only be done once patient is stable. Patients supplied with self-administered epinephrine must be informed of the shelf life of epinephrine and when they must come in to get a replacement.

  • Bee sting anaphylaxis for desensitisation.