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 UPPER OUTER THIGH DELTOID
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 • α1 – peripheral vasoconstriction via smooth muscle constriction • Increased SVR • Β1 – Increased Cadiac output through +vechrnontropy and inotropy • Β2 – 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 • 3rd 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.gloratadine 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) • https://nzphvc-01.otago.ac.nz/carm/ • 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 1:1000 0.5ml/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 2nd 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
