anaphylaxis
Post on 25-Dec-2015
11 Views
Preview:
DESCRIPTION
TRANSCRIPT
Anaphylaxis
Introduction
• Rapid onset of allergic manifestations in response to an allergen that has sensitised the immune system previously
• Anaphylactoid reactions are clinically indiscernible but do not have an immune-mediated underlying mechanism.
Pathophysiology
• Most common cause is drugs, insect bites and stings, and food
• An IgE mediated release of preformed vasoactive substances including histamine and leukotrienes occurs, resulting in clinical manifestations.
• Thereafter, vasodilation, increased capillary permeabilty, increased mucous production and bronchoconstriction
Clinical • Typically of sudden onset, important features:
– Respiratory• Upper: oropharyngeal oedema, rhinorrhea, layngeal
spasm or oedema• Lower: cough, dyspnoea, bronchospasm and
respiratory distress
– Cardiovascular• Hypotension, tachycardia or syncope
– Cutaneous• Erythema, urticaria, or angio-oedema with pruritus
– Gastrointestinal• Abdominal pain, vomiting or diarrhoea
Adult Guidelines
• Investigations:
- Majority of cases nil investigations required
- Severe cases may require standard pathology studies, CXR and ECG
Treatment
• Basic measures- Triage to appropriate area of ED- Attend to immediate life threat- ABC’s- Remove or cease administration of causative
agent- IV access and fluids
- Monitoring vital signs, ECG and O2 saturation
First line treatment
• O2 to maintain adequate saturation >92%
• Adrenaline- drug of choice in all serious cases - If stable (0.5mg IM of 1:1000) Rpt every 5 minutes as required
according to BP/Pulse/Respiratory function- If unstable initial IV bolus 0.75-1.5mcg/kg, then 10-20mcg IV
increments- If predominantly upper airway manifestations or bronchospasm-
5mg of 1:1000 solution via nebuliser
- IV Fluids
Second line treatment
• Antihistamines- H1 blockers- Promethazine 10-25mg IV, IM or oral
- H2 blockers- Ranitidine 50mg IV, or 300mg orally
• Steroids- Prednisolone 25-50mg orally- Hydrocortisone 100-250mg IV- Dexamethasone 4-8mg IV, IM
• Glucagon- Has a place when patient is on Beta Blockers and relatively resistant to
Adrenaline, or severe refractory anaphylaxis. 1mg IV repeated 5 minutely or by infusion
Disposition• 95% of patients have a uniphasic presentation, and will require
4-8hrs observation prior discharge
• Small amount of people will develop delayed recurrent symptoms, hence the time frame for observation
• If severe cases might require ICU admission
• Most cases can be discharged on antihistmines +/- steroids for 2-3 days with GP follow up
• If cause not known for anaphylaxis, will require further investigations by allergist or immunologist as outpatient
• Need to educate all patients how to manage this in a repeat episode and should be discharged and educated on an epipen
Guidelines
• Australian Prescriber Guidelines– http://www.australianprescriber.com/– Update 2011
top related