Clinical sciences for MRCP Part 1

Minutes after eating a takeaway containing peanuts, a 25-year-old man develops widespread urticaria, swelling of his lips and tongue, wheeze and stridor, and becomes hypotensive with a systolic of 80 mmHg. He is anxious and short of breath. What is the most likely diagnosis?

1. Septic shock Shock from infection, coming on more slowly. But sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger does not point to it.
2. Vasovagal syncope A faint with a slow heart rate and a quick recovery. That does not match sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
3. Anaphylaxis correct Correct. Sudden hives, swelling, wheeze and low blood pressure within minutes of eating peanuts is anaphylaxis.
4. Angioedema without anaphylaxis Swelling without airway or circulation collapse. It does not fit sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
5. Scombroid poisoning A histamine reaction from spoiled fish that can look similar. Here, sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger points elsewhere.

The point: Anaphylaxis is a severe, life-threatening, whole-body allergic reaction. Most often, it is a type I reaction driven by the antibody IgE: an allergen locks onto IgE sitting on mast cells and basophils (types of immune cell), which sets off a massive release of histamine and other chemical messengers. It comes on fast, usually within minutes of meeting a trigger such as food (nuts, shellfish), a drug (antibiotics, especially penicillins, and NSAIDs), an insect sting, or latex. The diagnosis is made clinically: a sudden start with rapidly worsening problems in the Airway, Breathing or Circulation (a harsh noise on breathing in, called stridor, and swelling; wheeze and low oxygen; or low blood pressure and collapse), usually together with skin and mucosal changes such as hives (urticaria) and swelling under the skin (angioedema), though skin changes can sometimes be absent. The single most important treatment is adrenaline given into the muscle of the outer thigh (0.5 mg of the 1 in 1000 strength in an adult), given straight away and repeated after 5 minutes if there is no improvement. Giving adrenaline late is the commonest avoidable reason people die from anaphylaxis. Alongside this, the patient is positioned appropriately (lying flat with the legs raised if their blood pressure is low, or sitting up if breathing is the main problem), given high-flow oxygen and fluids into a vein for low blood pressure, and the trigger is removed. Antihistamines and steroids are no longer used as the first treatment, and if given at all, they come after adrenaline. A blood test for mast-cell tryptase (a marker released by mast cells), taken during and after the reaction, supports the diagnosis after the event. Once the patient has recovered, they are watched for a second wave of symptoms (a biphasic reaction), given adrenaline auto-injector pens with training on how to use them, and referred to an allergy clinic to find the trigger. Anaphylaxis is a clear example of the type I hypersensitivity immunology that MRCP tests in clinical sciences.

Source: Resuscitation Council UK — emergency treatment of anaphylaxis guideline Resuscitation Council UK · tier 2, specialty society or college

Minutes after eating a takeaway containing peanuts, a 25-year-old man develops widespread urticaria, swelling of his lips and tongue, wheeze and stridor, and becomes hypotensive with a systolic of 80 mmHg. He is anxious and short of breath. What is the most appropriate investigation?

1. Serial serum mast-cell tryptase Supports the diagnosis after the event. It does not fit sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
2. Clinical recognition of sudden ABC compromise with a trigger correct Correct. Anaphylaxis is diagnosed clinically from sudden airway, breathing or circulation problems together with a trigger.
3. Allergy clinic referral and testing Confirms the exact allergen. But sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger does not point to it.
4. Observation for a biphasic reaction Needed because symptoms can come back. That does not match sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
5. Monitoring of oxygenation and blood pressure Tracks how severe the reaction is. Here, sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger points elsewhere.

The point: Anaphylaxis is a severe, life-threatening, whole-body allergic reaction. Most often, it is a type I reaction driven by the antibody IgE: an allergen locks onto IgE sitting on mast cells and basophils (types of immune cell), which sets off a massive release of histamine and other chemical messengers. It comes on fast, usually within minutes of meeting a trigger such as food (nuts, shellfish), a drug (antibiotics, especially penicillins, and NSAIDs), an insect sting, or latex. The diagnosis is made clinically: a sudden start with rapidly worsening problems in the Airway, Breathing or Circulation (a harsh noise on breathing in, called stridor, and swelling; wheeze and low oxygen; or low blood pressure and collapse), usually together with skin and mucosal changes such as hives (urticaria) and swelling under the skin (angioedema), though skin changes can sometimes be absent. The single most important treatment is adrenaline given into the muscle of the outer thigh (0.5 mg of the 1 in 1000 strength in an adult), given straight away and repeated after 5 minutes if there is no improvement. Giving adrenaline late is the commonest avoidable reason people die from anaphylaxis. Alongside this, the patient is positioned appropriately (lying flat with the legs raised if their blood pressure is low, or sitting up if breathing is the main problem), given high-flow oxygen and fluids into a vein for low blood pressure, and the trigger is removed. Antihistamines and steroids are no longer used as the first treatment, and if given at all, they come after adrenaline. A blood test for mast-cell tryptase (a marker released by mast cells), taken during and after the reaction, supports the diagnosis after the event. Once the patient has recovered, they are watched for a second wave of symptoms (a biphasic reaction), given adrenaline auto-injector pens with training on how to use them, and referred to an allergy clinic to find the trigger. Anaphylaxis is a clear example of the type I hypersensitivity immunology that MRCP tests in clinical sciences.

Source: Resuscitation Council UK — emergency treatment of anaphylaxis guideline Resuscitation Council UK · tier 2, specialty society or college

Minutes after eating a takeaway containing peanuts, a 25-year-old man develops widespread urticaria, swelling of his lips and tongue, wheeze and stridor, and becomes hypotensive with a systolic of 80 mmHg. He is anxious and short of breath. What is the most appropriate management?

1. Repeat adrenaline after 5 minutes if no improvement Given again if the reaction continues. Here, sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger points elsewhere.
2. Antihistamines and steroids only as secondary measures Given only after adrenaline, not instead of it. It does not fit sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
3. High-flow oxygen and intravenous fluids For low oxygen and low blood pressure. That does not match sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger.
4. Position the patient and remove the trigger Lie flat if blood pressure is low, sit up if breathing is the problem. But sudden hives, swelling, wheeze and low blood pressure within minutes of a food trigger does not point to it.
5. Immediate intramuscular adrenaline into the anterolateral thigh correct Correct. Adrenaline given straight into the outer-thigh muscle is the single most important treatment.

The point: Anaphylaxis is a severe, life-threatening, whole-body allergic reaction. Most often, it is a type I reaction driven by the antibody IgE: an allergen locks onto IgE sitting on mast cells and basophils (types of immune cell), which sets off a massive release of histamine and other chemical messengers. It comes on fast, usually within minutes of meeting a trigger such as food (nuts, shellfish), a drug (antibiotics, especially penicillins, and NSAIDs), an insect sting, or latex. The diagnosis is made clinically: a sudden start with rapidly worsening problems in the Airway, Breathing or Circulation (a harsh noise on breathing in, called stridor, and swelling; wheeze and low oxygen; or low blood pressure and collapse), usually together with skin and mucosal changes such as hives (urticaria) and swelling under the skin (angioedema), though skin changes can sometimes be absent. The single most important treatment is adrenaline given into the muscle of the outer thigh (0.5 mg of the 1 in 1000 strength in an adult), given straight away and repeated after 5 minutes if there is no improvement. Giving adrenaline late is the commonest avoidable reason people die from anaphylaxis. Alongside this, the patient is positioned appropriately (lying flat with the legs raised if their blood pressure is low, or sitting up if breathing is the main problem), given high-flow oxygen and fluids into a vein for low blood pressure, and the trigger is removed. Antihistamines and steroids are no longer used as the first treatment, and if given at all, they come after adrenaline. A blood test for mast-cell tryptase (a marker released by mast cells), taken during and after the reaction, supports the diagnosis after the event. Once the patient has recovered, they are watched for a second wave of symptoms (a biphasic reaction), given adrenaline auto-injector pens with training on how to use them, and referred to an allergy clinic to find the trigger. Anaphylaxis is a clear example of the type I hypersensitivity immunology that MRCP tests in clinical sciences.

Source: Resuscitation Council UK — emergency treatment of anaphylaxis guideline Resuscitation Council UK · tier 2, specialty society or college