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ANAPHYLAXIS

Anaphylaxis is an acute allergic process where a substance to which the individual has been previously exposed results in mast cell degranulation and massive mediator release. Anaphylactic shock is twice as common in women and atopy is present in about a third of cases.

Aetiology

• Foods: nuts, fish.

• Drugs: NSAIDs, antibiotics, anaesthetics.

• Stings

• Idiopathic Presentation

There is a spectrum of severity from mild to catastrophic, and treatment must be tailored to the individual situation.

Clinical features

• Airway compromise and breathing difficulties: stridor, wheeze, tachypnoea.

• Circulatory collapse: hypotension, tachycardia.

• Itch, skin rash, angio-oedema - may be completely absent.

• In about 20% abdominal or muscle pain or GI upset are major symptoms.

ACUTE ANAPHYLAXIS Bronchospasm and/or cardiovascular collapse.

Adrenaline should be given to all patients with respiratory difficulties and/or hypotension.

. Immediate action

O_ + Help Adrenaline

IV Fluids

• Discontinue administration of suspect drug, blood transfusion or IV fluid.

• GET HELP - call .

• ABC: maintain airway and give 100% oxygen by high flow with oxygen mask and reservoir bag or bag/mask/valve apparatus.

Intubation may be required early, particularly if stridor is present.

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• Commence basic life support (CPR) if no pulse present.

• Secure adequate IV access if not already.

• Monitor oxygen saturation and BP.

• ECG must be continuously monitored, and a defibrillator immediately available.

• Give adrenaline 500 micrograms intramuscular (0.5ml of  in 000 solution). Repeat in 5-0 mins if no better or getting worse.

• Give IV fluids. Hartmann’s solution, 0.9% saline or Gelofusine 10ml/

kg (about 500ml to 1 litre) can be used initially. Colloid may be more efficient at restoring blood volume especially in severe cases.

2. Supplementary action to damp down inflammation/prevent recurrence

• Give hydrocortisone 00mg IV (slowly).

• Give Antihistamines: chlorphenamine (chlorpheniramine) 0-0mg IV slowly.

• Give salbutamol 5mg nebuliser if wheeze present.

• Measure arterial blood gases and coagulation.

VERY SEVERE ANAPHYLAXIS

Most cases will resolve with the above treatment. However in the most severe cases with life-threatening shock or airway compromise, particularly in association with general anaesthesia, adrenaline should be given intravenously as described here.

• This is a rapidly life-threatening condition requiring experienced clinical management. Intravenous adrenaline boluses should only be given by, or under the direct supervision of, an appropriately experienced clinician.

• Give ADRENALINE INTRAVENOUSLY (especially in the presence of stridor or wheeze) starting with 50 to 00 micrograms (0.5-1 ml of 1 in 10,000 i.e. Minijet), with further 50 to 100 microgram aliquots as required.

• Adrenaline dose in cardiac arrest is 1 mg (10ml of 1 in 10,000).

SUBSEQUENT ACTION

Record allergy prominently in notes and explain to patient and family.

CONTINUING PROBLEMS (requiring ICU referral for:)

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• Salbutamol 5mg nebulised in 100% oxygen, repeated as necessary.

Always maintain oxygen therapy during administration of bronchodilators.

• Salbutamol 250 micrograms slowly IV (4micrograms/kg over at least 10 mins) as a loading dose followed by 5-20 micrograms/min infusion (directed by Senior Clinicians).

N.B. Can cause tachyarrhythmias, hypotension, hypokalaemia.

Alternatively (as directed by Senior Clinicians)

• Adrenaline by infusion 6mg diluted in 100ml of dextrose 5% at 3-10 ml per hour.

• Aminophylline 250mg IV over 20 mins by volumetric pump or syringe driver. This is usually sufficient but up to 6-8mg/kg can be used.

N.B. Can cause tachyarrhythmias, myocardial ischaemia and hypokalaemia. Caution in the elderly, IHD or if on oral theophylline.

Half loading dose if on theophylline or level unavailable.

Refractory hypotension and/or pulmonary oedema and/or bronchospasm requires ICU referral.

FURTHER MANAGEMENT Even if stabilised and improving:

• admit to ICU or HDU or appropriate monitored area.

• monitor respiratory rate, ECG, BP, SpO₂.

• continue steroids and anti-histamines orally or IV.

Follow up is crucial: over 60% of patients will have repeated attacks.

• Patients should be advised to wear a medic-alert type bracelet or talisman. Information on this is available from:

Anaphylaxis Campaign

01252 542029 [email protected] British Allergy Foundation

02083 038792 www.allergyfoundation.com email: [email protected]

• In food, insect or unknown allergies provide an Epipen or Anapen adrenaline injector and training in use.

• Referral to allergist is ideal but in Lothian this service is not available.

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1. An inhaled beta2-agonist such as salbutamol may be used as an adjunctive measure if bronchospasm is severe and does not respond rapidly to other treatment.

2. If profound shock judged immediately life threatening give CPR/ALS if necessary. Consider slow IV adrenaline (epinephrine) 1:10,000 solution. This is hazardous and is recommended only for an experienced practitioner who can also obtain IV access without delay.

Note the different strength of adrenaline (epinephrine) that may be required for IV use.

3. If adults are treated with an Epipen, the 300 micrograms will usually be sufficient. A second dose may be required. Half doses of adrenaline (epinephrine) may be safer for patients on amitriptyline, imipramine or a beta blocker.

Stridor, wheeze, respiratory distress or clinical signs of shock¹

Repeat in 5 minutes if no clinical improvement

Antihistamine (chlorphenamine) 10-20 mg IM/or slow IV

If clinical manifestations of shock do not respond to drug treatment

give 1-2 litres of IV fluid. ⁴ Rapid infusion and/or one repeat

dose may be necessary IN ADDITION

Figure 1 Anaphylactic Reactions: Treatment Algorithm for Adults by First Medical Responders

Consider when compatible history of severe allergic-type reaction with respiratory difficulty and/or hypotension

especially if skin changes present

Oxygen treatment when available

Adrenaline (epinephrine)^2,3 1:1000 solution 0.5 mL (500 micrograms) IM

For all severe or recurrent reactions and patients

with asthma give Hydrocortisone 100-500 mg IM/or slowly IV

ALGORITHM FOR FIRST MEDICAL RESPONDER TO ANAPHYLAXIS Advanced Life Support (UK) Algorithm