Anaphylaxis and Allergic Reactions Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Anaphylaxis and Allergic Reactions. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 1: A cardiovascular parameter helpful in diagnosis of anaphylaxis during anaesthesia:
- A. Bradycardia
- B. Dysrhythmia
- C. Increased peripheral vascular resistance
- D. Hypotension (Correct Answer)
Anaphylaxis and Allergic Reactions Explanation: ***Hypotension***
- **Hypotension** is a hallmark cardiovascular sign of anaphylaxis, occurring due to widespread **vasodilation** and increased vascular permeability.
- This symptom is often profound and unresponsive to initial fluid resuscitation due to the ongoing systemic release of inflammatory mediators.
*Bradycardia*
- While bradycardia can occur in some rare cases of anaphylaxis (e.g., **vasovagal response**), **tachycardia** is the more common cardiac response due to compensatory mechanisms.
- It is not a primary or consistent indicator of anaphylaxis, making it less helpful for diagnosis in this context.
*Dysrhythmia*
- **Dysrhythmias** can occur during anaphylaxis due to myocardial ischemia or electrolyte imbalances, but they are not a direct or consistent diagnostic feature.
- Their presence often reflects severe compromise or co-existing conditions rather than being a primary anaphylactic sign.
*Increased peripheral vascular resistance*
- Anaphylaxis is characterized by a significant **decrease in peripheral vascular resistance** due to mast cell and basophil degranulation releasing vasodilatory mediators like histamine.
- Therefore, an increase in peripheral vascular resistance would contradict the pathophysiology of anaphylaxis.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 2: Acute allergic reaction to the penicillin group of drugs is classified as:
- A. Type 1 reaction (Correct Answer)
- B. Type 2 reaction
- C. Type 3 reaction
- D. Type 4 reaction
Anaphylaxis and Allergic Reactions Explanation: ***Type 1 reaction***
- Penicillin allergy is a classic example of a **Type I hypersensitivity reaction**, mediated by **IgE antibodies**.
- Symptoms like **anaphylaxis**, **urticaria**, and **angioedema** develop rapidly upon re-exposure to the drug.
*Type 2 reaction*
- **Type II hypersensitivity reactions** involve **IgG** or **IgM antibodies** binding to antigens on cell surfaces, leading to cell destruction.
- Examples include **hemolytic anemia** due to drug-induced antibodies, which is not the primary mechanism of typical penicillin allergy.
*Type 3 reaction*
- **Type III hypersensitivity reactions** involve the formation of **immune complexes** (antigen-antibody complexes) that deposit in tissues.
- This can lead to conditions like **serum sickness** or **vasculitis**, which are less common manifestations of penicillin allergy.
*Type 4 reaction*
- **Type IV hypersensitivity reactions** are **delayed-type hypersensitivity (DTH)** reactions, mediated by **T cells** rather than antibodies.
- These reactions typically manifest 24-72 hours after exposure, as seen in **contact dermatitis**; while some penicillin reactions can be T-cell mediated, the acute, life-threatening allergic response is Type I.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 3: Which of the following is false regarding transfusion-associated anaphylactic reactions?
- A. Different from allergy
- B. Epinephrine is the drug of choice
- C. Washed blood products prevent it
- D. Seen in IgG deficient individuals (Correct Answer)
Anaphylaxis and Allergic Reactions Explanation: ***Seen in IgG deficient individuals***
- Transfusion-associated **anaphylactic reactions** are most commonly seen in **IgA-deficient individuals** who develop **anti-IgA antibodies** and receive blood products containing IgA.
- Anaphylaxis occurs when these pre-formed IgA antibodies react with donor IgA, leading to mast cell degranulation and severe allergic symptoms.
*Different from allergy*
- Transfusion-associated **anaphylactic reactions** are a severe form of allergic reaction, often distinguished by their **rapid onset** and life-threatening nature [1].
- While all allergies involve an immune response to an allergen, anaphylaxis represents the most extreme systemic manifestation.
*Epinephrine is the drug of choice*
- **Epinephrine** is indeed the **first-line treatment** for acute anaphylaxis, regardless of its cause, including transfusion-associated reactions [2].
- It acts rapidly to counteract the systemic effects of histamine and other mediators by acting on α and β adrenergic receptors [3].
*Washed blood products prevent it*
- **Washing blood products** (e.g., packed red blood cells or platelets) is an effective strategy to **remove plasma proteins**, including IgA.
- This is particularly crucial for patients with a known **IgA deficiency and anti-IgA antibodies** to prevent severe anaphylactic reactions.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 4: The percutaneous PAIR therapy used in the treatment of uncomplicated hepatic hydatid cyst can be associated with the following complications, except
- A. hypotension
- B. bradycardia (Correct Answer)
- C. vomiting
- D. anaphylaxis
Anaphylaxis and Allergic Reactions Explanation: ***bradycardia***
- **Bradycardia is not a recognized primary complication** of percutaneous aspiration, injection, and re-aspiration (PAIR) therapy for hydatid cysts.
- While bradycardia can occur as a **vasovagal response during any invasive procedure**, it is not specifically listed among the complications of PAIR therapy in standard medical literature.
- The typical cardiovascular manifestation of anaphylaxis (a known PAIR complication) is **tachycardia**, not bradycardia.
*hypotension*
- **Hypotension** is a well-documented complication of PAIR therapy, occurring due to **anaphylactic reaction** from leakage of antigenic hydatid fluid into the circulation.
- It can also result from **intra-abdominal hemorrhage** if a major vessel is inadvertently punctured during the procedure.
*vomiting*
- **Vomiting** can occur as part of a **systemic allergic reaction or anaphylaxis** triggered by the release of hydatid cyst contents.
- It may also be a manifestation of peritoneal irritation if cyst contents leak into the peritoneal cavity.
*anaphylaxis*
- **Anaphylaxis** is the most feared and well-documented complication of PAIR therapy, caused by the release of **highly antigenic hydatid cyst fluid** (containing protoscolices and hydatid antigens) into the host's system.
- This severe Type I hypersensitivity reaction can manifest with **hypotension, tachycardia, bronchospasm, urticaria, angioedema**, and in severe cases, cardiovascular collapse.
- Prophylactic antihistamines and corticosteroids are often administered to minimize this risk.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 5: A child with a known peanut allergy accidentally ingests a food containing peanuts and develops urticaria, vomiting, and wheezing within minutes. What is the first-line treatment?
- A. Oral antihistamines
- B. Subcutaneous epinephrine
- C. Intramuscular epinephrine (Correct Answer)
- D. High-dose corticosteroids
Anaphylaxis and Allergic Reactions Explanation: ***Intramuscular epinephrine***
- This patient is experiencing **anaphylaxis**, characterized by rapid-onset **urticaria**, **vomiting** (gastrointestinal involvement), and **wheezing** (respiratory involvement).
- **Epinephrine** is the **first-line treatment** for anaphylaxis due to its alpha-1 agonist effects (vasoconstriction to counteract hypotension and reduce angioedema) and beta-2 agonist effects (bronchodilation to relieve wheezing). Intramuscular administration ensures rapid absorption and systemic effect.
*Oral antihistamines*
- While antihistamines can help manage cutaneous symptoms like **urticaria** and **itching**, they do not address the life-threatening respiratory or cardiovascular symptoms of anaphylaxis.
- They are considered **adjunctive therapy** for mild allergic reactions but are not sufficient as first-line treatment for anaphylaxis.
*Subcutaneous epinephrine*
- **Subcutaneous administration** is historical and **not recommended** for anaphylaxis because it has a slower and less predictable absorption compared to intramuscular injection.
- The delay in onset of action can be critical in a rapidly progressing anaphylactic reaction.
*High-dose corticosteroids*
- **Corticosteroids** act too slowly to be useful as a primary treatment for acute anaphylaxis, as their effects take several hours to manifest.
- They are used as **adjunctive therapy** to prevent protracted or biphasic reactions, but not for the initial management of acute symptoms.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 6: Carbonic anhydrase inhibitor should not be given in:
- A. Epilepsy
- B. High altitude sickness
- C. Sulfonamide hypersensitivity (Correct Answer)
- D. Glaucoma
Anaphylaxis and Allergic Reactions Explanation: ***Sulfonamide hypersensitivity***
- Carbonic anhydrase inhibitors (CAIs) are **sulfonamide derivatives**, so they are absolutely contraindicated in patients with a history of **sulfonamide allergy**.
- Administration to such patients can lead to severe **hypersensitivity reactions**, including rash, fever, and even anaphylaxis.
*Epilepsy*
- **Acetazolamide**, a carbonic anhydrase inhibitor, can be used as an **adjunct therapy for certain types of epilepsy**, such as absence seizures.
- It works by reducing neuronal excitability through its effects on pH, thus it is not contraindicated but rather sometimes indicated.
*High altitude sickness*
- Carbonic anhydrase inhibitors like **acetazolamide** are commonly used to **prevent and treat high altitude cerebral and pulmonary edema** by inducing metabolic acidosis and stimulating respiration.
- This is a recognized therapeutic indication, not a contraindication.
*Glaucoma*
- CAIs are a **primary treatment for glaucoma** (both open-angle and angle-closure) because they reduce the production of aqueous humor, thereby lowering intraocular pressure.
- They are used both systemically and topically for this purpose, making it an indication, not a contraindication.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 7: Patient following peanut consumption presented with laryngeal edema, stridor, hoarseness of voice and swelling of tongue. Most likely diagnosis is:
- A. Foreign body bronchus
- B. Angioneurotic edema (Correct Answer)
- C. Foreign body larynx
- D. Pharyngeal abscess
Anaphylaxis and Allergic Reactions Explanation: ***Angioneurotic edema***
- The rapid onset of **laryngeal edema**, **stridor**, **hoarseness**, and **tongue swelling** following peanut consumption points to an allergic reaction, specifically **anaphylaxis** causing angioedema [1], [2].
- This is a life-threatening condition due to potential **airway obstruction**.
*Foreign body bronchus*
- While a foreign body could cause **stridor** if large enough to impact the trachea, symptoms like **laryngeal edema** and **tongue swelling** are not typical.
- It usually presents with sudden coughing, wheezing, and possibly dyspnea, often without rapid-onset, diffuse swelling.
*Foreign body larynx*
- A foreign body in the larynx might cause hoarseness and stridor, but **laryngeal edema** and **tongue swelling** are not primary features of a simple foreign body obstruction.
- The history of peanut ingestion and rapid systemic inflammatory response makes an allergic reaction more likely [2].
*Pharyngeal abscess*
- A pharyngeal abscess typically develops more slowly, with symptoms including **severe sore throat**, **fever**, and **difficulty swallowing**.
- It would not usually present with the rapid onset of severe **laryngeal edema** and **tongue swelling** immediately after peanut consumption.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 8: A patient undergoing surgery suddenly develops signs of anaphylaxis. What is the best immediate management?
- A. Give atropine
- B. Increase level of anesthesia
- C. Ask the surgeon to stop the surgery
- D. Give adrenaline (Correct Answer)
Anaphylaxis and Allergic Reactions Explanation: ***Give adrenaline***
- **Adrenaline (epinephrine)** is the first-line treatment for anaphylaxis due to its alpha-1 adrenergic effects (vasoconstriction, increasing blood pressure) and beta-2 adrenergic effects (bronchodilation).
- Its rapid administration is crucial to counteract systemic vasodilation, bronchospasm, and cardiovascular collapse characteristic of anaphylaxis.
*Give atropine*
- **Atropine** is an anticholinergic drug primarily used to treat **bradycardia**; it does not address the widespread vasodilation, bronchoconstriction, or histamine release seen in anaphylaxis.
- Giving atropine would not treat the underlying pathological mechanisms of an anaphylactic reaction.
*Increase level of anesthesia*
- Increasing the level of anesthesia might mask some symptoms but would not treat the underlying **hypotension**, **bronchospasm**, or other systemic effects of anaphylaxis.
- Anaphylaxis requires specific pharmacological intervention, not simply deeper sedation.
*Ask the surgeon to stop the surgery*
- While stopping the surgery might be a necessary step in severe cases to facilitate patient management, it is not the immediate **pharmacological intervention** required to treat the life-threatening symptoms of anaphylaxis.
- The immediate priority is to stabilize the patient's condition with appropriate medication.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 9: A man takes peanut and develops tongue swelling, neck swelling, stridor, hoarseness of voice. What is the probable diagnosis?
- A. FB in larynx
- B. Angioneurotic edema (Correct Answer)
- C. Parapharyngeal abscess
- D. FB bronchus
Anaphylaxis and Allergic Reactions Explanation: Andioneurotic edema
- The combination of **tongue swelling**, **neck swelling**, **stridor**, and **hoarseness of voice** following peanut ingestion is highly suggestive of **angioneurotic edema**, a severe allergic reaction that can lead to airway obstruction [1].
- This is a life-threatening condition requiring immediate medical intervention, often associated with generalized **anaphylaxis** when triggered by allergens [2].
*FB in larynx*
- While a **foreign body (FB) in the larynx** can cause stridor and hoarseness, the widespread swelling of the tongue and neck points away from a localized laryngeal obstruction [3].
- A laryngeal FB would typically be associated with a more sudden onset of choking and coughing, not diffuse edema [3].
*Parapharyngeal abscess*
- A **parapharyngeal abscess** would typically present with **fever**, **severe throat pain**, and **trismus** (difficulty opening the mouth), which are not mentioned in this scenario.
- The acute, rapid onset of symptoms after peanut consumption is inconsistent with the slower progression of an abscess.
*FB bronchus*
- A **foreign body in the bronchus** would primarily cause **coughing**, **wheezing**, and possibly **respiratory distress**, often unilateral, rather than severe global swelling of the tongue and neck.
- Inspiratory stridor and hoarseness are more indicative of upper airway involvement than bronchial obstruction.
Anaphylaxis and Allergic Reactions Indian Medical PG Question 10: A drug used to prevent niacin-induced flushing is
- A. Dexamethasone
- B. Aspirin (Correct Answer)
- C. Paracetamol
- D. Cetirizine
Anaphylaxis and Allergic Reactions Explanation: ***Aspirin***
- Niacin-induced flushing is mediated by **prostaglandins**, primarily prostaglandin D2 (PGD2), which cause vasodilation.
- **Aspirin**, being a non-steroidal anti-inflammatory drug (NSAID) and a cyclooxygenase (COX) inhibitor, blocks the synthesis of prostaglandins, thereby reducing flushing.
*Cetirizine*
- Cetirizine is a **second-generation H1 antihistamine** primarily used to treat allergic symptoms like rhinitis or urticaria.
- It does not significantly affect prostaglandin pathways implicated in niacin-induced flushing.
*Dexamethasone*
- Dexamethasone is a **corticosteroid** with potent anti-inflammatory and immunosuppressive effects.
- While it can broadly reduce inflammation, it is not the primary or most appropriate treatment for niacin-induced flushing, which is better managed with prostaglandin inhibitors.
*Paracetamol*
- Paracetamol (acetaminophen) is an **analgesic and antipyretic** that works primarily by inhibiting prostaglandin synthesis in the central nervous system.
- It has minimal anti-inflammatory effects and does not effectively reduce peripheral prostaglandin production responsible for niacin flush.
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