Respiratory Diseases Practice Questions

Q: A 1-year-old female infant is hospitalized for pneumonia. Bacterial cultures of the sputum have grown Pseudomonas aeruginosa. She has had two prior hospitalizations for severe respiratory infections. Her mother has noted that when she kisses her child, the child tastes 'salty.' The child has had weight loss that the mother attributes to frequent vomiting and diarrhea with bulky, foul-smelling fatty stools. The child is small for her age. Which of the following critical proteins is altered in this condition?

Cystic fibrosis transmembrane conductance regulator. ### Explanation The clinical presentation of recurrent pneumonia (specifically with **Pseudomonas aeruginosa**), failure to thrive, and **steatorrhea** (bulky, foul-smelling stools) in an infant is classic for **Cystic Fibrosis (CF)**. The pathognomonic sign mentioned—the mother noticing the child **tastes "salty"**—points directly to an abnormality in sweat chloride levels. **1. Why the Correct Answer is Right:** Cystic Fibrosis is caused by a mutation in the **CFTR (Cystic Fibrosis Transmembrane Conductance Regulator)** gene on chromosome 7. The CFTR protein is a cAMP-regulated chloride channel. In the lungs and pancreas, defective CFTR leads to thick, dehydrated secretions that obstruct airways (leading to infections) and pancreatic ducts (leading to malabsorption and steatorrhea). In sweat glands, it fails to reabsorb chloride, resulting in high salt concentration on the skin. **2. Why Incorrect Options are Wrong:** * **B. Dystrophin:** Mutations here cause Duchenne or Becker Muscular Dystrophy, characterized by progressive muscle weakness, not respiratory infections or malabsorption. * **C. alpha-1,4-Glucosidase (Acid Maltase):** Deficiency causes Pompe disease (GSD II), presenting with cardiomegaly and hypotonia. * **D. alpha-L-Iduronidase:** Deficiency causes Hurler Syndrome (MPS I), characterized by corneal clouding, hepatosplenomegaly, and coarse facial features. **3. NEET-PG High-Yield Pearls:** * **Most common mutation:** $\Delta$F508 (deletion of phenylalanine). * **Diagnosis:** Sweat Chloride Test (>60 mEq/L on two occasions) is the gold standard. * **Microbiology:** *S. aureus* is the most common lung pathogen in early childhood; *P. aeruginosa* becomes dominant in older children/adults. * **Associated findings:** Meconium ileus (newborns), nasal polyps, and bilateral absence of vas deferens (infertility in males).

Q: What is the most sensitive investigation for cystic fibrosis?

Sweat electrolytes. **Explanation:** **Cystic Fibrosis (CF)** is an autosomal recessive disorder caused by mutations in the **CFTR gene** (Cystic Fibrosis Transmembrane Conductance Regulator). This defect leads to impaired chloride transport across epithelial cells, resulting in thick, viscid secretions in the lungs and pancreas, and abnormally high salt content in sweat [1]. **Why Sweat Electrolytes is the Correct Answer:** The **Pilocarpine Iontophoresis Sweat Test** remains the **gold standard and most sensitive investigation** for diagnosing CF. It measures the concentration of chloride in sweat. A chloride level **>60 mmol/L** on two separate occasions is diagnostic. It is preferred because the physiological defect in CFTR is most consistently expressed in the sweat glands, where chloride cannot be reabsorbed from the primary sweat. **Why Other Options are Incorrect:** * **A & D (CT Scan/Tomogram):** While high-resolution CT (HRCT) is excellent for detecting bronchiectasis (a common complication of CF), it is not a diagnostic tool for the underlying genetic defect [1]. It shows the damage, not the disease itself. * **B (Ultrasound):** Ultrasound may show fatty infiltration of the pancreas or "meconium ileus" in neonates, but it lacks the sensitivity and specificity required for a definitive diagnosis of CF. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Immunoreactive Trypsinogen (IRT) is used for newborn screening. * **Most Common Mutation:** ΔF508 (a class II defect involving protein misfolding). * **Nasal Potential Difference:** Used as a diagnostic tool if sweat tests are borderline. * **Common Pathogens:** *Staphylococcus aureus* (early childhood) and *Pseudomonas aeruginosa* (most common in adults). * **Infertility:** 95% of males are infertile due to Congenital Bilateral Absence of the Vas Deferens (CBAVD) [1].

Q: What is the most common cause of ARDS in children?

Severe pneumonia with sepsis. **Explanation:** Acute Respiratory Distress Syndrome (ARDS) is a clinical syndrome characterized by acute onset of non-cardiogenic pulmonary edema and hypoxemia. In the pediatric population, the etiology is broadly categorized into direct (pulmonary) and indirect (extrapulmonary) lung injuries. **Why Option C is Correct:** According to the **Pediatric Acute Lung Injury Consensus Conference (PALICC)**, **severe pneumonia** is the most common cause of direct lung injury, while **sepsis** is the most common cause of indirect lung injury leading to ARDS in children. When combined, pneumonia-related sepsis accounts for the majority of pediatric ARDS cases globally. The underlying mechanism involves a massive inflammatory surge (cytokine storm) that increases alveolar-capillary permeability, leading to protein-rich fluid accumulation in the alveoli. **Why Other Options are Incorrect:** * **A. Aspiration:** While a significant cause of direct lung injury (especially gastric acid aspiration), it is statistically less frequent than infectious pneumonia. * **B. Injury (Trauma):** Physical trauma or pulmonary contusions can trigger ARDS, but these are more common in adolescents and adults rather than the general pediatric population. * **D. DIC:** Disseminated Intravascular Coagulation is typically a *complication* or a co-morbidity of sepsis rather than the primary inciting event for ARDS. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Pediatric ARDS (PARDS) is defined by the **PALICC criteria**, which uses the **Oxygenation Index (OI)** or Oxygenation Saturation Index (OSI) instead of the PaO2/FiO2 ratio used in the adult Berlin criteria. * **Radiology:** Requires new infiltrates consistent with acute pulmonary parenchymal disease (not fully explained by heart failure or fluid overload). * **Management:** Lung-protective ventilation (low tidal volume: 3–6 mL/kg) and maintaining plateau pressures <28 cm H2O.

Q: A child with a three-day history of upper respiratory tract infection presents with stridor that decreases on lying down. What is the most probable diagnosis?

Laryngotracheobronchitis. ### Explanation **Laryngotracheobronchitis (Croup)** is the most common cause of acute upper airway obstruction in children (typically 6 months to 3 years). It is usually preceded by a prodrome of upper respiratory infection (URI) symptoms like rhinorrhea and low-grade fever. The characteristic **barking cough** and **inspiratory stridor** occur due to subglottic narrowing. A key clinical feature is that the stridor often **decreases when the child is lying down or resting** (as agitation increases respiratory effort and turbulence), though it classically worsens at night. **Why other options are incorrect:** * **Acute Epiglottitis:** This is a medical emergency characterized by a rapid onset, high fever, and the "4 Ds": Drooling, Dysphagia, Distress, and Dysphonia. Patients prefer the "tripod position" and stridor **worsens** when lying supine due to the epiglottis falling back over the glottis. * **Foreign Body Aspiration:** This typically presents with a sudden, choking episode in a previously healthy child without a viral prodrome (no 3-day history of URI). * **Retropharyngeal Abscess:** While it presents with stridor and fever, it is distinguished by severe sore throat, neck stiffness (torticollis), and muffled "hot potato" voice. **High-Yield Clinical Pearls for NEET-PG:** * **Etiology:** Most common virus is **Parainfluenza type 1**. * **Radiology:** The classic X-ray finding is the **"Steeple Sign"** (subglottic narrowing) on the Anteroposterior (AP) view of the neck. * **Management:** Mild cases are managed with oral Dexamethasone. Severe cases (stridor at rest) require **Nebulized Adrenaline** and steroids. * **Westley Croup Score** is used to assess severity.

Q: Acute onset of cough, stridor, and respiratory distress in the absence of fever is suggestive of what condition?

Foreign body aspiration. ### Explanation **Correct Answer: A. Foreign Body Aspiration (FBA)** The hallmark of Foreign Body Aspiration is the **sudden, acute onset** of respiratory symptoms (cough, choking, stridor, or wheezing) in a previously healthy child. The **absence of fever** is a critical clinical differentiator, as it points toward a mechanical obstruction rather than an infectious process like croup or epiglottitis. In children aged 1–3 years, the "penetration syndrome" (sudden choking episode) is highly suggestive of FBA. **Why the other options are incorrect:** * **B. Acute Asthma:** While asthma causes respiratory distress and cough, it typically presents with recurrent episodes of expiratory wheezing rather than inspiratory stridor. It is often preceded by viral triggers or allergen exposure. * **C. Aspiration Pneumonia:** This is an inflammatory/infectious process resulting from the inhalation of gastric contents or oropharyngeal flora. It usually presents with **fever**, productive cough, and constitutional symptoms, rather than an instantaneous onset of stridor. * **D. Primary Complex:** This refers to the initial focus of pulmonary Tuberculosis. It is a chronic condition characterized by low-grade fever, weight loss, and a persistent cough, rather than acute respiratory distress. **NEET-PG High-Yield Pearls:** * **Most common site:** Right main bronchus (due to it being wider, shorter, and more vertical than the left). * **Most common age group:** 1 to 3 years (toddlers). * **Radiological sign:** "Check-valve" obstruction leading to **obstructive emphysema** (hyperlucency) on the affected side. * **Gold Standard Management:** Rigid Bronchoscopy (both diagnostic and therapeutic). Flexible bronchoscopy is preferred only for distal foreign bodies.

Q: A 2-month-old child has a respiratory rate of 45/minute. The child has not been accepting feeds for the last 4 days and shows signs of dehydration. Which type of pneumonia is this?

Severe pneumonia. ### Explanation The classification of pneumonia in children is based on the **WHO Integrated Management of Neonatal and Childhood Illness (IMNCI)** guidelines. **Why "Severe Pneumonia" is correct:** According to IMNCI guidelines for a child aged 2 months to 5 years, the presence of any **"General Danger Sign"** automatically classifies the condition as **Severe Pneumonia**. These signs include: 1. Inability to drink or breastfeed (as seen in this patient). 2. Persistent vomiting. 3. Convulsions. 4. Lethargy or unconsciousness. 5. Presence of chest indrawing. Even though the child’s respiratory rate (45/min) is technically normal for a 2-month-old (threshold for tachypnea is $\geq$ 50/min), the **inability to feed** is a critical danger sign that mandates hospitalization and parenteral antibiotics, categorizing it as Severe Pneumonia. **Analysis of Incorrect Options:** * **No Pneumonia:** Classified if there is no fast breathing AND no general danger signs. * **Pneumonia:** Classified if there is fast breathing ($\geq$ 50/min for 2–12 months) but **no** general danger signs and **no** chest indrawing. * **Very Severe Pneumonia:** This term was used in older WHO classifications. Under current IMNCI guidelines, "Severe Pneumonia" and "Very Severe Disease" are often grouped to simplify treatment protocols (referring to those requiring IV antibiotics). **NEET-PG High-Yield Pearls:** * **Tachypnea Cut-offs (IMNCI):** * < 2 months: $\geq$ 60/min * 2–12 months: $\geq$ 50/min * 12 months–5 years: $\geq$ 40/min * **Treatment:** Severe pneumonia requires **Injectable Ampicillin and Gentamicin** (or Ceftriaxone) as first-line therapy. * **Key Indicator:** In a child < 2 months, even "Chest Indrawing" is classified as Severe Disease/Pneumonia.

Q: A 5-year-old child suddenly develops stridor. Which one of the following would be the most likely diagnosis?

Foreign body aspiration. ### Explanation The key to answering this question lies in the word **"suddenly."** In a pediatric patient, the sudden onset of respiratory distress or stridor without preceding symptoms (like fever or cough) is a classic presentation of **Foreign Body Aspiration (FBA)**. #### Why Foreign Body Aspiration is Correct: FBA typically occurs in children aged 1–3 years but remains a critical diagnosis in older children. The hallmark is an **acute, "choking episode"** followed by sudden-onset stridor (if the object is in the upper airway) or localized wheezing (if in the lower airway). Unlike infectious causes, there is no prodrome of fever or upper respiratory infection. #### Why Other Options are Incorrect: * **Laryngomalacia:** This is the most common cause of *congenital* stridor. It typically presents in the first few weeks of life, is chronic, and is characterized by inspiratory stridor that worsens when the infant is supine or crying. It does not develop "suddenly" at age 5. * **Acute Laryngotracheobronchitis (Croup):** While common in children, it typically presents with a **prodrome** of runny nose and low-grade fever, followed by a characteristic "barking" cough and inspiratory stridor. It is rarely "sudden" in its initial onset. * **Acute Epiglottitis:** Although it has a rapid progression, it is usually accompanied by **high-grade fever**, drooling, and a "tripod position." The incidence has significantly decreased due to the HiB vaccine. #### NEET-PG High-Yield Pearls: * **Most common site for FBA:** Right main bronchus (due to it being wider, shorter, and more vertical). * **Gold Standard Investigation:** Rigid Bronchoscopy (both diagnostic and therapeutic). * **X-ray finding:** Often normal, but may show an "air-trapping" effect (obstructive emphysema) on expiration. * **Laryngomalacia:** Characterized by "omega-shaped" epiglottis on laryngoscopy.

Q: A couple presents for work-up of infertility after 5 years of unprotected intercourse. The wife denies any medical problems and notes regular menstrual cycles. The husband reports a history of chronic sinusitis and lower respiratory tract infections. Physical examination of the woman is unremarkable. Examination of the man reveals dextrocardia. Further work-up of the husband will most likely reveal?

Immotile sperm. **Explanation:** The clinical presentation of chronic sinusitis, recurrent lower respiratory tract infections, and **dextrocardia** (situs inversus) in a male with infertility is the classic triad of **Kartagener Syndrome**, a subset of **Primary Ciliary Dyskinesia (PCD)**. **1. Why "Immotile Sperm" is Correct:** PCD is an autosomal recessive disorder characterized by structural defects in the **dynein arms** of cilia and flagella. Since the tail of a spermatozoon is a modified flagellum sharing the same "9+2" microtubule structure as respiratory cilia, the defect leads to **impaired sperm motility (asthenozoospermia)**. While the sperm count is usually normal, they are unable to swim, leading to infertility. **2. Why Incorrect Options are Wrong:** * **Azoospermia:** This is the absence of sperm in the ejaculate. It is characteristic of **Cystic Fibrosis** (due to Congenital Bilateral Absence of the Vas Deferens - CBAVD), not PCD. * **Germinal cell aplasia (Sertoli cell-only syndrome):** This involves a lack of germ cells in the seminiferous tubules, leading to non-obstructive azoospermia. It is not associated with situs inversus or respiratory infections. * **Isolated gonadotropin deficiency:** Seen in **Kallmann Syndrome**, this presents with hypogonadotropic hypogonadism and anosmia, but not dextrocardia or bronchiectasis. **Clinical Pearls for NEET-PG:** * **Kartagener Triad:** Situs inversus, Bronchiectasis, and Sinusitis. * **Diagnostic Gold Standard:** Electron microscopy of ciliary ultrastructure (showing absent dynein arms) or genetic testing (DNAI1/DNAH5 mutations). * **Nasal Nitric Oxide:** Screening test for PCD; levels are typically very low. * **PCD vs. Cystic Fibrosis:** Both cause recurrent infections, but PCD presents with **situs inversus (50%)** and **immotile sperm**, whereas CF presents with **pancreatic insufficiency** and **CBAVD (azoospermia)**.

Q: Which of the following is NOT an indication for admission in pneumonia?

Fever of 39°C. In the management of childhood pneumonia, the decision to admit is based on the **IMNCI (Integrated Management of Neonatal and Childhood Illness)** and WHO guidelines, which prioritize clinical signs of respiratory distress and systemic danger signs over isolated physiological parameters like temperature. ### Why Option A is Correct **Fever (even 39°C/102.2°F)** is a common symptom of pneumonia but is **not** an independent indication for hospitalization. In the absence of other "danger signs," a child with a cough and fast breathing (Pneumonia) can be managed at home with oral antibiotics (e.g., Amoxicillin) and supportive care for fever (e.g., Paracetamol). ### Why the Other Options are Incorrect Options B, C, and D are all classified as **"Severe Pneumonia"** or "Very Severe Disease," necessitating urgent referral and inpatient parenteral antibiotics: * **Cyanosis (Option B):** Indicates hypoxemia and impending respiratory failure. * **Chest Retraction (Option C):** Specifically, lower chest wall indrawing is a hallmark sign of severe respiratory distress in children. * **Not Feeding Well (Option D):** Inability to drink or breastfeed is a "General Danger Sign" indicating systemic compromise or exhaustion. ### High-Yield Clinical Pearls for NEET-PG * **Fast Breathing Thresholds:** <2 months: ≥60/min; 2–12 months: ≥50/min; 12–60 months: ≥40/min. * **IMNCI Classification:** * **Pneumonia:** Fast breathing only → Home care (Oral Amoxicillin). * **Severe Pneumonia:** Any danger sign (indrawing, cyanosis, lethargy, inability to feed, convulsions) → Hospitalize (IV Ampicillin + Gentamicin). * **Stridor** in a calm child is also an indication for immediate admission.

Question 1

A 1-year-old female infant is hospitalized for pneumonia. Bacterial cultures of the sputum have grown Pseudomonas aeruginosa. She has had two prior hospitalizations for severe respiratory infections. Her mother has noted that when she kisses her child, the child tastes 'salty.' The child has had weight loss that the mother attributes to frequent vomiting and diarrhea with bulky, foul-smelling fatty stools. The child is small for her age. Which of the following critical proteins is altered in this condition?

Accepted Answer

Cystic fibrosis transmembrane conductance regulator

Answer

Dystrophin

Answer

alpha-1,4-Glucosidase

Answer

alpha-L-Iduronidase

Question 2

What is the most sensitive investigation for cystic fibrosis?

Accepted Answer

Sweat electrolytes

Answer

CT scan

Answer

Ultrasound

Answer

Tomogram

Question 3

Cystic fibrosis is inherited as an autosomal recessive condition. A normal couple has one daughter affected with the disease. They are now planning to have another child. What is the chance of her sibling being affected by the disease?

Accepted Answer

1/2

Answer

0

Answer

1/4

Answer

3/4

Question 4

What is the most common cause of ARDS in children?

Accepted Answer

Severe pneumonia with sepsis

Answer

Aspiration

Answer

Injury

Answer

DIC

Question 5

A child with a three-day history of upper respiratory tract infection presents with stridor that decreases on lying down. What is the most probable diagnosis?

Accepted Answer

Laryngotracheobronchitis

Answer

Acute Epiglottitis

Answer

Foreign body aspiration

Answer

Retropharyngeal abscess

Question 6

Acute onset of cough, stridor, and respiratory distress in the absence of fever is suggestive of what condition?

Accepted Answer

Foreign body aspiration

Answer

Acute asthma

Answer

Aspiration pneumonia

Answer

Primary complex

Question 7

A 2-month-old child has a respiratory rate of 45/minute. The child has not been accepting feeds for the last 4 days and shows signs of dehydration. Which type of pneumonia is this?

Accepted Answer

Severe pneumonia

Answer

No pneumonia

Answer

Pneumonia

Answer

Very severe pneumonia

Question 8

A 5-year-old child suddenly develops stridor. Which one of the following would be the most likely diagnosis?

Accepted Answer

Foreign body aspiration

Answer

Laryngomalacia

Answer

Acute laryngotracheobronchitis

Answer

Acute epiglottitis

Question 9

A couple presents for work-up of infertility after 5 years of unprotected intercourse. The wife denies any medical problems and notes regular menstrual cycles. The husband reports a history of chronic sinusitis and lower respiratory tract infections. Physical examination of the woman is unremarkable. Examination of the man reveals dextrocardia. Further work-up of the husband will most likely reveal?

Accepted Answer

Immotile sperm

Answer

Azoospermia

Answer

Germinal cell aplasia

Answer

Isolated gonadotropin deficiency

Question 10

Which of the following is NOT an indication for admission in pneumonia?

Accepted Answer

Fever of 39°C

Answer

Cyanosis

Answer

Chest retraction

Answer

Not feeding well

Respiratory Diseases — MCQs

Respiratory Diseases — MCQs

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