Chemical Burns — MCQs

10 questions

In a post-burn patient, which of the following is true?

What is the classification of intelligence corresponding to an IQ score of 90-109?

A lady with 50% TBSA burn with involvement of dermis and subcutaneous tissue came to the emergency department. The burns will be classified as:

What is the first aid treatment for acid contact with the skin?

What is the key pathophysiological difference between acid and alkali injuries in terms of tissue necrosis?

A hospital implements a policy to reduce occupational hand dermatitis in healthcare workers. They propose: (A) Switching from latex to nitrile gloves, (B) Installing alcohol-based hand rub dispensers, (C) Providing emollients, (D) Reducing glove use frequency. Synthesize the best evidence-based strategy.

Evaluate the following scenario: A 38-year-old worker in an electronics manufacturing unit develops hand dermatitis. Initial patch testing shows multiple positive reactions to metals (nickel, cobalt, chromium). Despite workplace modifications and protective equipment, the dermatitis persists. Re-evaluation reveals positive patch test to colophony. What is the best strategic approach?

A 45-year-old florist develops dermatitis on hands and forearms. Patch testing shows positive reactions to Compositae mix and sesquiterpene lactones. She also has scattered airborne pattern dermatitis on face and neck. Analyzing this pattern, what is the most likely diagnosis?

Q10

A 32-year-old dental technician presents with hyperkeratotic fissured dermatitis on fingertips despite using vinyl gloves. Patch testing to rubber accelerators is negative, but shows positive reaction to methacrylate. Analysis of the clinical presentation suggests which underlying mechanism?

Chemical Burns Indian Medical PG Practice Questions and MCQs

Question 1: In a post-burn patient, which of the following is true?

A. Hypokalemic alkalosis
B. Hyperkalemic alkalosis
C. Hypokalemic acidosis
D. Hyperkalemic acidosis (Correct Answer)

Explanation: ### Hyperkalemic acidosis - **Massive cell destruction** in severe burns leads to the release of intracellular potassium, causing **hyperkalemia** [1]. - **Metabolic acidosis** often results from tissue hypoperfusion, anaerobic metabolism, and accumulation of lactic acid due to shock and organ dysfunction [1]. *Hypokalemic alkalosis* - This condition is characterized by **low potassium levels** and **elevated pH**, which are not typical early responses to severe burns. - Would more likely be seen with significant **gastrointestinal losses** or certain diuretic use. *Hyperkalemic alkalosis* - While hyperkalemia can occur, the burn injury process typically leads to **acidosis** rather than alkalosis due to tissue damage and hypoperfusion. - This combination is generally contradictory as **severe hyperkalemia** is often accompanied by acidosis. *Hypokalemic acidosis* - **Hypokalemia** is not an immediate finding in severe burns; instead, **hyperkalemia** is expected due to cellular lysis. - Although **acidosis** is common, the potassium derangement described here is inconsistent with acute burn pathophysiology.

Question 2: What is the classification of intelligence corresponding to an IQ score of 90-109?

A. Below average
B. Average (Correct Answer)
C. Slightly below average
D. Above average

Explanation: ***Average*** - An **IQ score** range of **90-109** is traditionally classified as **Average** intelligence. - This range represents the **mean** and surrounding **standard deviation** of IQ scores in the general population. *Below average* - This classification usually corresponds to IQ scores in the range of **70-79** or **80-89**, depending on the specific scale. - It does not represent the central tendency of the population's intelligence. *Slightly below average* - This category typically corresponds to IQ scores in the range of **80-89**. - It falls just below the average range but is not as low as the "below average" classification. *Above average* - This classification is typically assigned to IQ scores that are in the range of **110-119** or higher. - It signifies cognitive abilities that are greater than the majority of the population.

Question 3: A lady with 50% TBSA burn with involvement of dermis and subcutaneous tissue came to the emergency department. The burns will be classified as:

A. 3rd degree burn (Correct Answer)
B. 2nd degree superficial
C. 2nd degree deep
D. 1st degree

Explanation: ***3rd degree burn*** - **Third-degree burns** involve the entire thickness of the skin (dermis and epidermis) and often extend into the **subcutaneous tissue**, muscle, or bone. - These burns typically appear dry, leathery, and often lack pain sensation due to nerve destruction. *2nd degree superficial* - **Superficial second-degree burns** involve the epidermis and the superficial part of the dermis, often presenting with **blisters** and painful, red, moist skin. - They do not extend to the subcutaneous tissue, which is a key feature of the burn described. *2nd degree deep* - **Deep second-degree burns** involve the epidermis and deeper layers of the dermis, but not the entire dermis or subcutaneous tissue. - While they can be less painful and appear dry, the involvement of **subcutaneous tissue** pushes the classification to third-degree. *1st degree* - **First-degree burns** only affect the epidermis, causing redness and pain but **no blistering** or damage to deeper layers. - These are typically sunburns or minor scalds and do not involve the dermis or subcutaneous tissue.

Question 4: Match the following drugs in Column A with their contraindications in Column B. | Column A | Column B | | :-- | :-- | | 1. Morphine | 1. QT prolongation | | 2. Amiodarone | 2. Thromboembolism | | 3. Vigabatrin | 3. Pregnancy | | 4. Estrogen preparations | 4. Head injury |

A. A-1, B-3, C-2, D-4
B. A-4, B-1, C-3, D-2 (Correct Answer)
C. A-3, B-2, C-4, D-1
D. A-2, B-4, C-1, D-3

Explanation: ***A-4, B-1, C-3, D-2*** - **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms. - **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes. - **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development. - **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation. *A-1, B-3, C-2, D-4* - This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications. - It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy. *A-3, B-2, C-4, D-1* - This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications. - It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation. *A-2, B-4, C-1, D-3* - This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications. - It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.

Question 5: What is the first aid treatment for acid contact with the skin?

A. Wash with strong alkali
B. Wash with copious amounts of water (Correct Answer)
C. Refer to higher centre
D. Wash with mild alkali agent

Explanation: ***Wash with copious amounts of water*** - The primary first aid for acid contact with the skin is immediate and prolonged **irrigation with copious amounts of water**. This helps to dilute the acid and wash away residual chemicals, minimizing tissue damage. - Flushing should continue for at least **20-30 minutes** or until medical help arrives, even if the pain subsides, to ensure thorough removal of the corrosive agent. *Wash with strong alkali* - Using a strong alkali to neutralize an acid burn can lead to an **exothermic reaction**, generating significant heat and causing further tissue damage. - This approach carries a high risk of worsening the chemical burn and should be strictly avoided. *Refer to higher centre* - While referral to a higher center may be necessary for severe burns, it is not the **immediate first aid step**. Delaying initial management to seek advanced care can worsen the burn. - **Immediate irrigation** is crucial to prevent further chemical injury and should precede any transfer decisions. *Wash with mild alkali agent* - Similar to strong alkalis, even a mild alkali agent can cause an **exothermic reaction** when mixed with acid on the skin, potentially increasing tissue damage rather than mitigating it. - The most effective and safest approach is **dilution with water**, not neutralization with bases.

Question 6: What is the key pathophysiological difference between acid and alkali injuries in terms of tissue necrosis?

A. Acid injuries cause coagulative necrosis
B. Alkali injuries lead to deeper tissue damage
C. Acid injuries are less severe than alkali injuries
D. Alkali injuries cause liquefactive necrosis (Correct Answer)

Explanation: ***Alkali injuries cause liquefactive necrosis*** - **Alkali burns** result in **liquefaction necrosis**, which involves the dissolution of tissue and cells, leading to a much deeper and progressive injury as the alkali penetrates further into tissues. - This is the **key pathophysiological difference** that distinguishes alkali from acid injuries - the TYPE of necrosis (liquefactive vs coagulative). - This type of necrosis allows the alkali to continue damaging underlying tissues and can lead to more extensive and severe scarring and complications. *Acid injuries cause coagulative necrosis* - While this statement is **medically true**, it only describes what acids do without explicitly stating the **difference** or comparison with alkali injuries. - The question asks for the KEY **difference**, and this option presents only one half of the comparison. - **Acid burns** typically cause **coagulation necrosis**, forming a coagulum or eschar that precipitates proteins and creates a barrier, thereby limiting the depth of penetration. - The correct answer (alkali → liquefactive necrosis) better captures the distinguishing pathophysiological feature. *Alkali injuries lead to deeper tissue damage* - This statement is true but serves as a **consequence** of the underlying **liquefactive necrosis** rather than the primary pathophysiological mechanism itself. - The liquefaction process continuously destroys cells and extracellular matrix, enabling the caustic agent to propagate deeply into the tissue. - This describes the OUTCOME rather than the KEY pathophysiological mechanism. *Acid injuries are less severe than alkali injuries* - This is a **generalization about severity** rather than identifying the specific pathophysiological mechanism of tissue death. - While generally true due to the **coagulation necrosis** limiting the depth of penetration of acids, severity can vary based on concentration, duration of exposure, and other factors. - The formation of a protective eschar in acid burns often prevents further significant tissue destruction, unlike the progressive damage seen in alkali burns.

Question 7: A hospital implements a policy to reduce occupational hand dermatitis in healthcare workers. They propose: (A) Switching from latex to nitrile gloves, (B) Installing alcohol-based hand rub dispensers, (C) Providing emollients, (D) Reducing glove use frequency. Synthesize the best evidence-based strategy.

A. Implement all four measures as glove occlusion worsens dermatitis
B. Implement only A and C to reduce costs
C. Implement A, B, and C; avoiding D as it compromises infection control (Correct Answer)
D. Focus only on B and C as glove material is not the primary issue

Explanation: ***Implement A, B, and C; avoiding D as it compromises infection control*** - Combining **non-latex (nitrile) gloves**, **alcohol-based rubs**, and **emollients** is the evidence-based triad for reducing **irritant contact dermatitis** and **Type I hypersensitivity** while maintaining skin barrier integrity. - Reducing the frequency of glove use (D) is an inappropriate strategy because it directly **compromises infection control** and increases the risk of **bloodborne pathogen exposure**. *Implement all four measures as glove occlusion worsens dermatitis* - While **glove occlusion** can contribute to dermatitis, intentionally reducing glove use (D) violates standard precautions for **patient and provider safety**. - The goal is to optimize the **type of glove** and **skin care regimen** rather than sacrificing necessary barrier protection. *Implement only A and C to reduce costs* - Excluding **alcohol-based hand rubs (B)** is counterproductive, as frequent washing with water and detergent is actually more **irritating to the skin** than alcohol rubs. - A strategy based solely on cost ignores the clinical evidence that **barrier creams and emollients** work best when integrated with less damaging hand hygiene methods. *Focus only on B and C as glove material is not the primary issue* - This ignores the significant prevalence of **latex allergy** and sensitivity to **accelerants** found in standard gloves, which contributes to **allergic contact dermatitis**. - Switching to **nitrile gloves (A)** is a critical step in a comprehensive occupational policy to eliminate **Type I latex hypersensitivity** risks.

Question 8: Evaluate the following scenario: A 38-year-old worker in an electronics manufacturing unit develops hand dermatitis. Initial patch testing shows multiple positive reactions to metals (nickel, cobalt, chromium). Despite workplace modifications and protective equipment, the dermatitis persists. Re-evaluation reveals positive patch test to colophony. What is the best strategic approach?

A. The persistent dermatitis indicates evolution to chronic actinic dermatitis
B. Colophony in soldering flux is the relevant occupational allergen; the metal sensitivities may be cross-reactions or co-sensitization (Correct Answer)
C. All positive reactions are equally relevant and complete job change is mandatory
D. The multiple sensitivities indicate systemic contact dermatitis requiring systemic therapy

Explanation: ***Colophony in soldering flux is the relevant occupational allergen; the metal sensitivities may be cross-reactions or co-sensitization*** - **Colophony** (rosin) is a frequent sensitizer in the **electronics industry**, where it is used as a flux in **soldering** to prevent oxidation. - Persistence of symptoms despite metal avoidance highlights the importance of identifying the **relevant allergen** versus incidental background sensitivity or **cross-reactivity**. *The persistent dermatitis indicates evolution to chronic actinic dermatitis* - **Chronic actinic dermatitis** is a photosensitive condition and is not a typical progression of **allergic contact dermatitis** caused by chemical exposure. - There is no clinical evidence of **photosensitivity** or UV-induced lesions mentioned in this occupational scenario. *All positive reactions are equally relevant and complete job change is mandatory* - Not all positive **patch tests** translate to clinical relevance; some may represent **excited skin syndrome** or past, non-relevant exposures. - A **job change** is a last resort; the management focus should be on specific **allergen substitution** or improved engineering controls for the **colophony** exposure. *The multiple sensitivities indicate systemic contact dermatitis requiring systemic therapy* - **Systemic contact dermatitis** occurs when an allergen is medicinally or dietarily ingested, not through **occupational cutaneous contact**. - Primary management involves **allergen avoidance** and topical therapists rather than initiating long-term **systemic immunosuppression** for manageable contactants.

Question 9: A 45-year-old florist develops dermatitis on hands and forearms. Patch testing shows positive reactions to Compositae mix and sesquiterpene lactones. She also has scattered airborne pattern dermatitis on face and neck. Analyzing this pattern, what is the most likely diagnosis?

A. Irritant contact dermatitis from fertilizers
B. Phototoxic dermatitis from plant handling
C. Combined contact and airborne contact dermatitis from Compositae family plants (Correct Answer)
D. Atopic dermatitis exacerbated by occupation

Explanation: ***Combined contact and airborne contact dermatitis from Compositae family plants*** - The patient exhibits classic **occupational sensitization** to **sesquiterpene lactones**, which are the primary allergens found in the **Compositae (Asteraceae)** plant family common in floristry. - The dual presentation includes **direct contact dermatitis** on the hands/forearms and **airborne contact dermatitis** on the face and neck caused by aerosolized plant particles or pollen. *Irritant contact dermatitis from fertilizers* - This typically presents as a localized reaction to harsh chemicals and would not explain the specific **positive patch test** to sesquiterpene lactones. - **Irritant dermatitis** usually lacks the distinct **airborne pattern** on the face and neck unless there is significant volatile exposure, which is less common with standard solid fertilizers. *Phototoxic dermatitis from plant handling* - Phototoxic reactions (like **phytophotodermatitis**) usually cause a **streaky, blistering** rash limited to sun-exposed areas where the plant sap made direct contact. - It is primarily triggered by **furocoumarins** (e.g., in limes or celery) rather than the sesquiterpene lactones identified in this patient's diagnostic testing. *Atopic dermatitis exacerbated by occupation* - While occupational stress can flare atopy, **atopic dermatitis** typically involves flexural surfaces and has a chronic, relapsing history rather than a specific **airborne distribution**. - The **positive patch test** for specific plant allergens strongly indicates a **Type IV hypersensitivity** (allergic contact) rather than a primary atopic constitutional skin barrier defect.

Question 10: A 32-year-old dental technician presents with hyperkeratotic fissured dermatitis on fingertips despite using vinyl gloves. Patch testing to rubber accelerators is negative, but shows positive reaction to methacrylate. Analysis of the clinical presentation suggests which underlying mechanism?

A. Cross-reaction between vinyl and methacrylate
B. The methacrylate monomer penetrates vinyl gloves causing sensitization (Correct Answer)
C. Protein contact dermatitis from dental materials
D. Irritant dermatitis unrelated to methacrylate sensitivity

Explanation: ***The methacrylate monomer penetrates vinyl gloves causing sensitization*** - **Methacrylates** are small, highly reactive chemicals used in dental materials that easily penetrate **vinyl and latex gloves** within minutes. - This leads to **allergic contact dermatitis**, classically presenting as **hyperkeratotic fissured dermatitis** on the fingertips of dental professionals despite glove use. *Cross-reaction between vinyl and methacrylate* - Cross-reactivity occurs when the immune system reacts to structurally similar chemicals; however, **vinyl (PVC)** is a polymer that is not chemically related to **methacrylates**. - The issue is the **permeability** of the glove material to the monomer, not an immunological mistake between two different substances. *Protein contact dermatitis from dental materials* - **Protein contact dermatitis** is an IgE-mediated (Type I) or delayed-type (Type IV) reaction typically caused by high molecular weight proteins like **natural rubber latex** or food proteins. - Methacrylates are **small molecules (haptens)**, and the clinical presentation of hyperkeratotic fissures is more characteristic of standard **allergic contact dermatitis**. *Irritant dermatitis unrelated to methacrylate sensitivity* - While dental professionals are at risk for **irritant contact dermatitis** due to frequent handwashing, the **positive patch test** to methacrylate confirms an underlying allergic mechanism. - Irritant reactions usually do not show the strong, specific **delayed hypersensitivity** response seen on a patch test that correlates precisely with the patient's occupational exposure.

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