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. Hives, swelling, wheeze and low blood pressure within minutes of eating peanuts, in a nut-allergic man, is anaphylaxis.
2. Hereditary angioedema Repeated swelling with no hives, that does not respond to adrenaline. But the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen does not point to it.
3. Urticaria and angioedema without systemic features Skin signs alone, with no airway or circulation problem. It does not fit the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
4. Asthma exacerbation Wheeze and breathlessness without low blood pressure or a known trigger. That does not match the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
5. Scombroid poisoning Flushing and symptoms after eating spoiled fish. Here, the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen points elsewhere.

The point: Anaphylaxis is a severe allergic reaction that comes on fast and can be fatal. The one treatment that saves lives is adrenaline, given into the muscle without delay. It is diagnosed when a hive-like rash (urticaria) or swelling (angioedema) comes on suddenly, together with an airway, breathing or circulation problem. It can also be diagnosed from low blood pressure alone after contact with a known allergen, because the skin signs can be absent. Common triggers are foods, insect stings and drugs. The immediate treatment is adrenaline injected into the muscle of the outer thigh, repeated every five minutes if needed. Lay the patient flat with the legs raised, or let them sit up if breathing is hard. Never stand them up suddenly, because this can drop the heart's output and cause death. Give high-flow oxygen and fluid through a drip for low blood pressure. Antihistamines and steroids are back-up treatments only, and never replace adrenaline. Watch for a second wave of symptoms hours later, called a biphasic reaction. Before the patient goes home, give two adrenaline injector pens, teach how to use them, give a written action plan, and refer to an allergy specialist. The most common mistake is giving adrenaline too late or not giving it at all.

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 This guides whether more adrenaline is needed. That does not match the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
2. Serial mast cell tryptase A blood test that supports the diagnosis after the event. It does not fit the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
3. Allergy service referral for testing Find the exact allergen through specialist testing. Here, the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen points elsewhere.
4. Clinical recognition of anaphylaxis correct Correct. It is diagnosed by the picture in front of you and treated right away, not after tests.
5. Assessment of airway, breathing and circulation This guides what to do next. But the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen does not point to it.

The point: Anaphylaxis is a severe allergic reaction that comes on fast and can be fatal. The one treatment that saves lives is adrenaline, given into the muscle without delay. It is diagnosed when a hive-like rash (urticaria) or swelling (angioedema) comes on suddenly, together with an airway, breathing or circulation problem. It can also be diagnosed from low blood pressure alone after contact with a known allergen, because the skin signs can be absent. Common triggers are foods, insect stings and drugs. The immediate treatment is adrenaline injected into the muscle of the outer thigh, repeated every five minutes if needed. Lay the patient flat with the legs raised, or let them sit up if breathing is hard. Never stand them up suddenly, because this can drop the heart's output and cause death. Give high-flow oxygen and fluid through a drip for low blood pressure. Antihistamines and steroids are back-up treatments only, and never replace adrenaline. Watch for a second wave of symptoms hours later, called a biphasic reaction. Before the patient goes home, give two adrenaline injector pens, teach how to use them, give a written action plan, and refer to an allergy specialist. The most common mistake is giving adrenaline too late or not giving it at all.

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. Remove or stop the trigger where possible Such as stopping a drug going into the vein. But the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen does not point to it.
2. High-flow oxygen and intravenous fluids These support breathing and circulation. It does not fit the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
3. Intramuscular adrenaline without delay correct Correct. Adrenaline into the muscle is the life-saving first treatment, and antihistamines and steroids do not replace it.
4. Repeat adrenaline every five minutes as needed Given again if the first dose is not enough. That does not match the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen.
5. Prescribe two adrenaline autoinjectors and an action plan Give two injector pens with training, a written plan and specialist referral. Here, the combination of hives, swelling, wheeze and low blood pressure within minutes of a known allergen points elsewhere.

The point: Anaphylaxis is a severe allergic reaction that comes on fast and can be fatal. The one treatment that saves lives is adrenaline, given into the muscle without delay. It is diagnosed when a hive-like rash (urticaria) or swelling (angioedema) comes on suddenly, together with an airway, breathing or circulation problem. It can also be diagnosed from low blood pressure alone after contact with a known allergen, because the skin signs can be absent. Common triggers are foods, insect stings and drugs. The immediate treatment is adrenaline injected into the muscle of the outer thigh, repeated every five minutes if needed. Lay the patient flat with the legs raised, or let them sit up if breathing is hard. Never stand them up suddenly, because this can drop the heart's output and cause death. Give high-flow oxygen and fluid through a drip for low blood pressure. Antihistamines and steroids are back-up treatments only, and never replace adrenaline. Watch for a second wave of symptoms hours later, called a biphasic reaction. Before the patient goes home, give two adrenaline injector pens, teach how to use them, give a written action plan, and refer to an allergy specialist. The most common mistake is giving adrenaline too late or not giving it at all.

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