⚠️ 1. Definition
Anaphylaxis is a rapid, life-threatening allergic reaction affecting the whole body.
It happens when the immune system overreacts to an allergen, releasing large amounts of chemicals such as histamine, which cause widespread symptoms.
If untreated, it can lead to:
- Shock
- Respiratory failure
- Death
🧬 2. Pathophysiology (What happens in the body)
Anaphylaxis is usually an IgE-mediated immune reaction.
🔬 Process:
- Allergen enters the body (e.g., food or sting)
- Immune system overreacts
- Mast cells and basophils release histamine
- Blood vessels widen and leak fluid
- Airways tighten and swell
⏱️ Onset:
- Usually within minutes
- Can occur up to 1–2 hours after exposure
⚠️ Biphasic reaction:
A second wave of symptoms may occur 4–6 hours later, even without re-exposure.
🍽️ 3. Common Triggers
- Peanuts and tree nuts
- Shellfish and other foods
- Penicillin and other medications
- Insect stings (bees, wasps)
- Latex exposure
🧠 4. Signs and Symptoms (Multisystem Reaction)
Anaphylaxis affects multiple body systems at once.
🧴 Skin:
- Hives (urticaria)
- Redness (flushing)
- Swelling (angioedema – lips, tongue, face)
🫁 Respiratory:
- Wheezing
- Shortness of breath
- Throat swelling
- Hoarse voice
❤️ Cardiovascular:
- Low blood pressure (hypotension)
- Rapid heartbeat (tachycardia)
- Dizziness or collapse
🤢 Gastrointestinal:
- Vomiting
- Diarrhoea
- Abdominal cramps
🚨 5. Emergency Management
Anaphylaxis is a medical emergency requiring immediate action.
💉 First-line treatment:
- Epinephrine (adrenaline) injection into the outer thigh
🧪 Effects of epinephrine:
- Opens airways (bronchodilation)
- Raises blood pressure (vasoconstriction)
- Reverses allergic reaction
🛌 Positioning:
- Lay person flat
- Elevate legs (if possible)
🫁 Additional support:
- High-flow oxygen
- IV fluids (hospital setting)
💊 Secondary treatments (not life-saving alone):
- Antihistamines (e.g., diphenhydramine)
- Steroids (reduce inflammation later)
🔍 6. Key Clinical Distinctions
⚖️ Allergic reaction vs Anaphylaxis:
- Allergic reaction: affects one system (e.g., skin rash only)
- Anaphylaxis: affects multiple systems and is life-threatening
⚖️ Types of reactions:
- Anaphylactic: IgE-mediated (classic allergy pathway)
- Anaphylactoid: non-IgE mediated but clinically identical in treatment
🐝 7. First Aid Notes
- Remove stingers by scraping sideways, not squeezing
- Call emergency services immediately if symptoms appear
- Do not “wait and see” — symptoms can escalate quickly
📊 8. Prognosis and Importance of Timing
- Rapid treatment = high survival rate
- Delay in epinephrine increases risk of death
- Early recognition is critical
📌 Key Summary
Anaphylaxis is:
- Sudden
- Severe
- System-wide
- Life-threatening
- Treatable only with immediate epinephrine
No comments:
Post a Comment