Anaphylaxis SHO presentation Tom Francis ICU Registrar

Anaphylaxis What is it Pathophysiology Common causes / precipitants Features / signs Treatment After-care / discharge

Anaphylactic shock Type 1 IgE mediated (usually) hypersensitivity reaction Chain Reaction Release of histamine and other cytokines from mast cells and basophills Causes contraction of bronchial smooth muscles, vasodilation of peripheral vasculature, capillary leak and cardiac muscle depression

ADRENALINE Mainstay of treatment is Adrenaline 0.5mg IM ADRENALINE

Precipitants / causes Drugs – Abx, cross reactivity B-lactams – Muscle relaxants – IV contrast Food Bee stings / wasp / horse fly

IM injection DELTOID UPPER OUTER THIGH

Recognition Airway – Airway oedema – larynx, lips, tongue, eyelids – Stridor is a sign of airway obstruction Breathing – Bronchial smooth muscle constriction – wheeze, respiratory distress, increased work of breathing Circulation – Relaxation of vascular smooth muscle – Vasodilation, hypotension and erythema – Increased capillary permeability leading to loss of fluid from circulation : hypotension, tissue swelling, urticaria and Angioedema

Urticaria

Angioedema

ADRENALINE 0.5mg IM Half of 1/1000 vial (the small one) Found in emergency box on all wards Can repeat every 5 mins 0.5mg ADRENALINE IM

Adrenaline α 1 – peripheral vasoconstriction via smooth muscle constriction – Increased SVR Β 1 – Increased Cadiac output through +ve chrnontropy and inotropy Β 2 – Bronchial smooth muscle relaxation Also acts directly on mast cells preventing further histamine release

Promethazine (Phenergan) 25mg slow IV injection (can use IM) Sedating anti-histamine (H1) Prevents capillary leak and helps treat hypotension due to loss of intravascular fluid If persistant hypotension despite treatment with adrenaline can use ranitidine (H2) as second line. 50mg Ranitidine IV slowly

Hydrocortisone 200mg IV hydrocortisone Requires reconstituion with sterile water OF NO VALUE IN IMMEDIATE RESUSCITATION Is of value to prevent rebound anaphylaxis though onset of several hours, should be given to prevent further deterioration in severely affected patients

IV Fluids Vasodilation and increased vascular permeability 3 rd spacing of fluid into interstitial space DISTRIBUTIVE SHOCK 1 litre Crystalloid or colloid STAT once Adrenaline given IM 1 – 3 litres commonly required 50mg Ranitidine can help persitant low BP

Treatment ADRENALINE 0.5mg IM Airway (and supplemental Oxygen) – nebulised adrenaline 5mg (5 x 1/1000) – Consider intubation. Breathing – bronchospasm usually responds to adrenaline, can give nebulised salbutamol 5mg if wheeze persists. Treat as acute asthma Circulation – Raise legs / head down on bed if hypotension – Large bore IV access – 1 litre IVI stat – 50mg Ranitine IV if persistant

Treatment Mainstay of treatment is Adrenaline 0.5mg IM ADRENALINE

Where now? Pts who require treatment for anaphylaxis need to be discussed with ICU Rebound Anaphylaxis is a concern Tryptase levels to confirm diagnosis – <1 Hour, 8 hours, 24 hours

Discharge post anaphylaxis Oral antihistamine e.g loratadine 3/7 Oral Steroid 3/7 – Reduces risk of further reaction Refer for specific allergy diagnosis Epi-pen prescription – 300mcg Adrenaline

Further Mx… ACC form Refer to GP for Medic Alert bracelet Fill out an Alert/Adverse Reactions/Allergies form Complete CARM report if a medication allergy – (Centre for adverse reactions monitoring) – – Or easily found on google!

Don’t forget!!! 0.5mg IM ADRENALINE

Paediatrics Adrenaline 0.01ml/kg of 1:1000 IM – Minimum 0.1 ml (10kg) – Maximum 0.5 ml (50kg) Dose will be between 100 – 500mcg IM

Airway obstruction Sit child upright Neb adrenaline 1: ml/kg, max 6ml. Dilute to at least 4ml

Cardiovascular compromise Poor perfusion, tachycardia, hypotension IV access – Consider IO 20ml/kg NaCl Rpt as required – 4% albumin after 2 nd bolus Adrenaline infusion

Bronchospasm Salbutamol neb 5mg PRN/continuous Consider IV salbutamol Intubation / ventilation

Further Mx Hydrocortisone 4mg/kg IV Q6H H1 antihistamine (loratadine / cetirizine) – Itch – Angioedema PO Ranitidine 1-2mg/kg (max 150mg) in sever reactions If require more than 1x dose Adrenaline require 24 hour admission

References: ALS handbook (UK) ACLS level 7 handbook (NZ) NZ resuscitation website Starship PICU guidelines