Emergency, trauma and toxicology for AMC MCQ

A 19 year old man eats a dish containing peanuts and within minutes develops widespread urticaria, lip and tongue swelling, wheeze and difficulty breathing, then becomes light-headed with a blood pressure of 82/50 mmHg. He has a known nut allergy. A junior doctor reaches for an antihistamine and hydrocortisone. What is the most likely diagnosis?

1. Anaphylaxis correct Correct. Urticaria, angioedema, wheeze and hypotension minutes after peanuts in a nut-allergic man is anaphylaxis.
2. Hereditary angioedema Recurrent angioedema without urticaria, unresponsive to adrenaline. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it worth considering.
3. Urticaria and angioedema without systemic features Skin features alone without airway or circulation compromise. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes the systemic features matter.
4. Asthma exacerbation Wheeze and breathlessness without hypotension or the trigger. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen raises it.
5. Scombroid poisoning Flushing and symptoms after spoiled fish. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen argues for the history.

The point: Anaphylaxis is a severe, rapidly evolving, potentially fatal allergic reaction, and the single treatment that saves lives is intramuscular adrenaline given without delay. It is defined by the acute onset of an illness with skin or mucosal features such as urticaria and angioedema plus airway, breathing or circulation compromise, or by hypotension after exposure to a known allergen, and skin features can be absent. Common triggers are foods, insect stings and drugs. The immediate management is intramuscular adrenaline into the anterolateral thigh, repeated every five minutes as needed, with the patient lying flat with the legs raised, or sitting if breathing is difficult, and never standing them up suddenly, which can cause a fatal drop in cardiac output. Give high-flow oxygen and intravenous fluids for hypotension. Antihistamines and steroids are secondary and never replace adrenaline. Observe for a biphasic reaction. On discharge, prescribe two adrenaline autoinjectors, train the patient, provide an action plan, and refer to an allergy service. The commonest error is delayed or withheld adrenaline.

Source: Therapeutic Guidelines (Australia) — Emergency: anaphylaxis Therapeutic Guidelines (Australia) · tier 3, national formulary

A 19 year old man eats a dish containing peanuts and within minutes develops widespread urticaria, lip and tongue swelling, wheeze and difficulty breathing, then becomes light-headed with a blood pressure of 82/50 mmHg. He has a known nut allergy. A junior doctor reaches for an antihistamine and hydrocortisone. What is the most appropriate initial investigation?

1. Assessment of severity and response To guide repeated adrenaline. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it discriminating.
2. Serial mast cell tryptase Supports the diagnosis retrospectively. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen indicates it.
3. Allergy service referral for testing To identify the allergen. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it the follow-up.
4. Clinical recognition of anaphylaxis correct Correct. It is a clinical diagnosis treated immediately, not one that waits for tests.
5. Assessment of airway, breathing and circulation Guides the response. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it necessary.

The point: Anaphylaxis is a severe, rapidly evolving, potentially fatal allergic reaction, and the single treatment that saves lives is intramuscular adrenaline given without delay. It is defined by the acute onset of an illness with skin or mucosal features such as urticaria and angioedema plus airway, breathing or circulation compromise, or by hypotension after exposure to a known allergen, and skin features can be absent. Common triggers are foods, insect stings and drugs. The immediate management is intramuscular adrenaline into the anterolateral thigh, repeated every five minutes as needed, with the patient lying flat with the legs raised, or sitting if breathing is difficult, and never standing them up suddenly, which can cause a fatal drop in cardiac output. Give high-flow oxygen and intravenous fluids for hypotension. Antihistamines and steroids are secondary and never replace adrenaline. Observe for a biphasic reaction. On discharge, prescribe two adrenaline autoinjectors, train the patient, provide an action plan, and refer to an allergy service. The commonest error is delayed or withheld adrenaline.

Source: Therapeutic Guidelines (Australia) — Emergency: anaphylaxis Therapeutic Guidelines (Australia) · tier 3, national formulary

A 19 year old man eats a dish containing peanuts and within minutes develops widespread urticaria, lip and tongue swelling, wheeze and difficulty breathing, then becomes light-headed with a blood pressure of 82/50 mmHg. He has a known nut allergy. A junior doctor reaches for an antihistamine and hydrocortisone. What is the most appropriate next step in management?

1. Prescribe two adrenaline autoinjectors and an action plan With training and allergy referral. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it the discharge bundle.
2. High-flow oxygen and intravenous fluids For breathing and circulation. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it supportive.
3. Intramuscular adrenaline without delay correct Correct. Intramuscular adrenaline is the life-saving first-line treatment, and antihistamines and steroids do not replace it.
4. Remove or stop the trigger where possible Such as stopping a drug infusion. Urticaria, angioedema, wheeze and hypotension minutes after a known allergen makes it appropriate.
5. Position lying flat with legs raised He is laid flat with legs raised and never stood up suddenly, and urticaria, angioedema, wheeze and hypotension minutes after a known allergen here points elsewhere.

The point: Anaphylaxis is a severe, rapidly evolving, potentially fatal allergic reaction, and the single treatment that saves lives is intramuscular adrenaline given without delay. It is defined by the acute onset of an illness with skin or mucosal features such as urticaria and angioedema plus airway, breathing or circulation compromise, or by hypotension after exposure to a known allergen, and skin features can be absent. Common triggers are foods, insect stings and drugs. The immediate management is intramuscular adrenaline into the anterolateral thigh, repeated every five minutes as needed, with the patient lying flat with the legs raised, or sitting if breathing is difficult, and never standing them up suddenly, which can cause a fatal drop in cardiac output. Give high-flow oxygen and intravenous fluids for hypotension. Antihistamines and steroids are secondary and never replace adrenaline. Observe for a biphasic reaction. On discharge, prescribe two adrenaline autoinjectors, train the patient, provide an action plan, and refer to an allergy service. The commonest error is delayed or withheld adrenaline.

Source: Therapeutic Guidelines (Australia) — Emergency: anaphylaxis Therapeutic Guidelines (Australia) · tier 3, national formulary