Management of Anaphylaxis

The following is based on current practice in the Hunter Area Intensive Care and Emergency Departments.

(1) Prior to commencing antivenom therapy obtain intravenous access (large bore cannula, fluids running) and have adrenaline available drawn up in a syringe (see below). Have SPPS or equivalent available.

(2) As a minimum, monitor the patient on an ECG machine and by frequent palpation of systemic BP. Preferred monitoring includes automated BP recording and oximetry.

(3) In case of bronchospasm, sudden fall in blood pressure or other warning sign of anaphylaxis temporarily suspend the antivenom infusion and begin adrenaline.

(4) Give adrenaline 1:1000, 0.25 - 0.5 mL as an intramuscular injection. This dose may be repeated every 5 to 10 minutes if required.

In severe anaphylaxis, adrenaline may be given intravenously. Give adrenaline 1:10,000, 0.5-1.0 mL over 1 minute and repeat as required. In prolonged reactions, an adrenaline infusion may be necessary.

(5) Meanwhile consult with an appropriate ICU re retrieval and maintain frequent contact with the ICU.

(6) Volume load with SPPS may be required, in addition to adrenaline, aiming to achieve a systolic BP of about 100 mmHg.

(7) Inhaled bronchodilators such as salbutamol may be used as an adjunct to adrenaline but should not be used in preference to adrenaline unless the bronchospasm is mild and the only major manifestation of anaphylaxis.

(8) There is no role for steroids in the acute management of anaphylaxis, however steroids (hydrocortisone 200 mg intravenously) may be given following resuscitation if further antivenom is required.

(9) When the reaction is controlled then, if clinically indicated, antivenom should be continued while closely monitoring for recurrence of symptoms (consult Toxicologist/Toxinologist).

(10) There is no role for antihistamines in the management of anaphylaxis.

NOTE: The half-life of adrenaline is less than 2 minutes; any excessive rise in BP should be short lived.

The following regime is based on the John Hunter Hospital protocol for the management of anaphylaxis in children.

(1) Prior to commencing antivenom therapy obtain intravenous access and have adrenaline (see below) available. Consider use of bone needle if no other access available.

(2) In case of bronchospasm, sudden fall in blood pressure or other warning sign of anaphylaxis temporarily suspend the antivenom infusion and begin adrenaline.

(3) Place patient in recumbent position.

(4) Clear airway and give 100% O2 and support ventilation as necessary.

(5) Give adrenaline 1:1000, 0.01 mL/kg IM. (Infants: 0.05 to 0.1 mL of 1:1000. Children: 0.1 to 0.3 mL of 1:1000) Repeat if necessary in 5 minutes.

(6) If hypotensive, give 10% SPPS 10 mL/kg IV STAT.

(7) If there is no response to IM adrenaline or if the peripheral circulation is poor or shock is severe, then give adrenaline 1:100,000 (mix 0.1 mL of 1:1000 aqueous adrenaline in 10 mL normal saline = 10 microgram/mL concentration) in a dose of 1 mL/kg IV over 10 min and repeat 10 mL/kg SPPS IV STAT.

Examples:

• for an average child age 2 years, weight is about 12 kg, i.e. 12 mL 1:100,000 adrenaline and 120 mL of SPPS
• for an average child age 5 years, weight is 18 kg, i.e. 18 mL and 180 mL respectively
• for an average child age 10 years, weight is 32 kg, i.e. 32 mL and 320 mL respectively

(8) If an adrenaline infusion is necessary prepare a 1:200,000 dilution by mixing 0.5 mL of 1:1000 aqueous adrenaline in 100 mL of 5% dextrose in water = 5 microgram/mL concentration. Infuse at a rate of 0.1 microgram/kg/min (up to a maximum of 1.0 microgram/kg/min) as necessary to maintain blood pressure.

(9) Meanwhile consult with an appropriate ICU re retrieval and maintain frequent contact with the ICU.

(10) Inhaled bronchodilators such as salbutamol may be used as an adjunct to adrenaline but should not be used in preference to adrenaline unless the bronchospasm is mild and the only major manifestation of anaphylaxis.

(11) There is no role for steroids in the acute management of anaphylaxis, however steroids (hydrocortisone 4 mg/kg intravenously) may be given following resuscitation if further antivenom required.

(12) When the reaction is controlled then, if clinically indicated, antivenom should be continued while closely monitoring for recurrence of symptoms (consult Toxicologist/Toxinologist).

(13) There is no role for antihistamines in the acute management of anaphylaxis.

NOTE: The half life of adrenaline is less than 2 minutes; any excessive rise in BP should be short lived.