Respiratory Diseases Practice Questions

Q: Which of the following statements is true about cystic fibrosis?

Immune reactive trypsin may be checked on the Guthrie card.. ### Explanation **Correct Answer: B. Immune reactive trypsin may be checked on the Guthrie card.** **Why it is correct:** Newborn screening for Cystic Fibrosis (CF) utilizes the **Guthrie card** (heel prick test). In CF, pancreatic duct obstruction leads to the leakage of pancreatic enzymes into the blood. **Immunoreactive Trypsinogen (IRT)** levels are elevated in affected neonates. If IRT is high, it is followed by DNA analysis or a sweat chloride test for confirmation. **Analysis of Incorrect Options:** * **Option A:** The defect is in the **CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein**, which is a **Chloride channel**, not a sodium channel. Sodium transport is affected secondarily (increased reabsorption). * **Option C:** The most common mutation is the **deletion of Phenylalanine** (not Valine) at position **508** ($\Delta$F508) on the long arm of **Chromosome 7**. * **Option D:** For a sweat chloride test (Pilocarpine Iontophoresis), a value **$\geq$ 60 mmol/L** is diagnostic of CF. Values between 30–59 mmol/L are considered intermediate/borderline. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Recessive. * **Earliest Manifestation:** Meconium ileus (seen in ~15-20% of newborns). * **Gold Standard Diagnosis:** Sweat Chloride Test (Pilocarpine Iontophoresis). * **Common Infections:** *Staphylococcus aureus* (early childhood) and *Pseudomonas aeruginosa* (most common cause of chronic pulmonary infection). * **Infertility:** 95% of males are infertile due to **Congenital Bilateral Absence of Vas Deferens (CBAVD)**; spermatogenesis is usually normal. * **Radiology:** "Finger-in-glove" appearance on CXR due to mucoid impaction.

Q: A child presents with fever and a barky cough. On examination, the respiratory rate is 36/min, stridor is present only on crying, and the temperature is 39 degrees Celsius. There are no other abnormal findings. What is the next logical step in management?

Dexamethasone. ### Explanation The clinical presentation of a **barky cough, fever, and inspiratory stridor** in a child is classic for **Croup (Laryngotracheobronchitis)**, most commonly caused by the Parainfluenza virus [1]. To determine the management, we must assess the severity using the **Westley Croup Score**. This patient has **Mild Croup**, characterized by stridor that occurs only when agitated/crying, no intercostal retractions, and no cyanosis [2]. 1. **Why Dexamethasone is correct:** Current clinical guidelines (including Nelson’s Pediatrics) recommend that **all children with croup**, even those with mild symptoms, should receive a single dose of **Dexamethasone (0.15 mg/kg to 0.6 mg/kg)** [4]. It reduces laryngeal edema, decreases the need for subsequent nebulization, and shortens hospital stays. 2. **Why other options are incorrect:** * **Surfactant administration:** Used for Respiratory Distress Syndrome (RDS) in neonates, not for upper airway obstruction. * **Racemized epinephrine:** Reserved for **Moderate to Severe Croup** (stridor at rest, significant retractions) [3]. Since this child only has stridor when crying, epinephrine is not yet indicated. * **Observation and reassurance:** While supportive care is important, "observation alone" is no longer the standard of care, as steroids have been proven to prevent progression to severe respiratory distress [4]. ### Clinical Pearls for NEET-PG: * **X-ray Finding:** "Steeple Sign" (subglottic narrowing) on AP view of the neck. * **Most Common Pathogen:** Parainfluenza virus Type 1. * **Age Group:** Typically 6 months to 3 years [1]. * **Management Tip:** If Racemic Epinephrine is used, the child must be observed for at least 2–4 hours for "rebound phenomenon" (return of symptoms as the drug wears off) [3].

Q: All of the following are seen in a patient with cystic fibrosis except?

Metabolic acidosis. Explanation: Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the **CFTR gene**, leading to defective chloride transport across epithelial membranes [1]. **Why Metabolic Acidosis is the Correct Answer (The "Except"):** Patients with CF do **not** develop metabolic acidosis; instead, they are prone to **Metabolic Alkalosis**. This occurs due to excessive loss of sodium and chloride in sweat (the "salty baby" syndrome). To compensate for the loss of chloride, the kidneys increase the reabsorption of bicarbonate and excrete hydrogen ions, leading to a state known as **Pseudo-Bartter Syndrome** (hypokalemic, hypochloremic metabolic alkalosis). **Analysis of Incorrect Options:** * **A. Hypochloremia:** This is a classic finding. The defective CFTR protein prevents chloride reabsorption in sweat ducts, leading to high chloride concentration in sweat and low serum chloride levels [1]. * **C. Recurrent Pneumonias:** Thick, viscid mucus in the airways impairs mucociliary clearance, leading to chronic colonization by pathogens like *Staphylococcus aureus* (in childhood) and *Pseudomonas aeruginosa* (in adults) [1]. * **D. Steatorrhoea:** Pancreatic insufficiency occurs in ~85% of patients. Blocked pancreatic ducts lead to a deficiency of digestive enzymes, resulting in fat malabsorption and foul-smelling, oily stools. **NEET-PG High-Yield Pearls:** * **Diagnosis:** Sweat Chloride test (Gold Standard) > 60 mEq/L. * **Most Common Mutation:** ΔF508 (Class II mutation - protein misfolding) [1]. * **Infertility:** 95% of males are infertile due to **Congenital Bilateral Absence of Vas Deferens (CBAVD)**; spermatogenesis is usually normal. * **Newborn Screening:** Measurement of **Immunoreactive Trypsinogen (IRT)**.

Q: Which of the following is not true about idiopathic pulmonary hemosiderosis?

Eosinopenia. **Idiopathic Pulmonary Hemosiderosis (IPH)** is a rare condition characterized by the triad of iron deficiency anemia, hemoptysis, and transient pulmonary infiltrates. It results from recurrent episodes of diffuse alveolar hemorrhage (DAH). ### **Explanation of Options** * **B. Eosinopenia (Correct):** This is the incorrect statement regarding IPH. In fact, **peripheral eosinophilia** is observed in approximately 10–20% of cases during the acute phase of the disease. Eosinopenia is not a feature of IPH. * **A. Iron Deficiency Anemia:** This is a hallmark feature. Recurrent bleeding into the alveoli traps iron in the form of hemosiderin within alveolar macrophages. Since this iron cannot be recycled back into the systemic circulation, it leads to microcytic hypochromic anemia. * **C. Increased Bilirubin:** During an acute episode of pulmonary hemorrhage, the breakdown of extravasated red blood cells in the lungs leads to the release of heme. This results in elevated levels of **indirect (unconjugated) bilirubin**, mimicking a hemolytic picture. * **D. Increased Reticulocyte Count:** The body attempts to compensate for the blood loss and subsequent anemia by increasing erythropoiesis, leading to a high reticulocyte count. ### **NEET-PG High-Yield Pearls** * **Diagnosis:** The gold standard for diagnosis is a **lung biopsy**, but the presence of **hemosiderin-laden macrophages** (siderophages) in gastric aspirate or bronchoalveolar lavage (BAL) is highly suggestive. * **Chest X-ray:** Shows transient, patchy perihilar infiltrates during acute episodes; chronic cases show interstitial fibrosis (honeycombing). * **Heiner Syndrome:** A specific variant of IPH associated with **hypersensitivity to cow's milk**. * **Treatment:** Acute episodes are managed with corticosteroids; immunosuppressants (like Azathioprine) are used for maintenance.

Q: Fast breathing in a child less than 2 months is defined as a respiratory rate more than what value?

60 breaths per minute. **Explanation:** The definition of **fast breathing** is a critical component of the **IMNCI (Integrated Management of Neonatal and Childhood Illness)** guidelines used to diagnose pneumonia and respiratory distress in pediatric patients. The respiratory rate (RR) thresholds are age-dependent because baseline respiratory rates naturally decrease as a child matures. **Why Option C is Correct:** For a child **less than 2 months of age**, the threshold for fast breathing is **≥ 60 breaths per minute**. At this age, the chest wall is highly compliant and the metabolic demand is high, leading to a faster baseline rate. A rate of 60 or more is a sensitive indicator of lower respiratory tract involvement or sepsis. **Analysis of Incorrect Options:** * **Option A (40 bpm):** This is the threshold for fast breathing in children aged **12 months to 5 years**. * **Option B (50 bpm):** This is the threshold for fast breathing in infants aged **2 months to 12 months**. * **Option D (70 bpm):** While this indicates significant respiratory distress, it is not the standardized IMNCI cutoff for defining "fast breathing" in any age group. **High-Yield Clinical Pearls for NEET-PG:** 1. **Counting Rule:** To accurately diagnose fast breathing, the child must be calm (not crying or feeding), and the RR must be counted for a **full 60 seconds**. 2. **Young Infants (<2 months):** If the first count is 60 or more, IMNCI protocol requires a **second count**. Fast breathing is confirmed only if both counts are ≥ 60 bpm. 3. **Danger Signs:** In children <2 months, fast breathing is categorized as **"Very Severe Disease,"** requiring immediate injectable antibiotics and urgent referral. 4. **Chest Indrawing:** In this age group, mild chest indrawing is normal; only **severe chest indrawing** is considered a clinical red flag.

Q: How does a child's respiratory physiology differ from that of an adult?

Smaller airways. **Explanation:** The pediatric respiratory system is not merely a miniature version of the adult system; it possesses distinct anatomical and physiological characteristics. **Why "Smaller Airways" is Correct:** The most critical anatomical difference is the **smaller diameter of the airways**. According to **Poiseuille’s Law**, resistance to airflow is inversely proportional to the fourth power of the radius ($R \propto 1/r^4$). In an infant, even 1 mm of mucosal edema significantly reduces the cross-sectional area and increases airway resistance exponentially compared to an adult. Furthermore, the pediatric airway is more compliant due to less cartilage support, making it prone to dynamic collapse. **Analysis of Incorrect Options:** * **B. Increased oxygen demand:** While children do have a higher metabolic rate and oxygen consumption ($6\text{–}8 \text{ mL/kg/min}$ vs. $3\text{–}4 \text{ mL/kg/min}$ in adults), this is a metabolic demand rather than a primary structural/physiological "difference in respiratory mechanics" in the context of this classic comparison. * **C. Decreased tidal volume:** On a **per kilogram basis**, tidal volume is relatively constant across ages ($6\text{–}8 \text{ mL/kg}$). * **D. Decreased residual volume:** Children actually have a lower **Functional Residual Capacity (FRC)** relative to their oxygen demand, but their closing volume is higher, leading to earlier airway closure. **High-Yield Clinical Pearls for NEET-PG:** * **Narrowest part of the airway:** In children <8 years, it is the **Cricoid cartilage** (funnel-shaped larynx), whereas in adults, it is the Glottis (cylindrical). * **Diaphragm:** Children have fewer **Type I (slow-twitch, fatigue-resistant) muscle fibers** in their diaphragm (25% in newborns vs. 50% in adults), making them prone to early respiratory failure. * **Compliance:** Infants have high chest wall compliance but low lung compliance.

Q: What is the most likely cause of acute onset of cough, stridor, and dyspnea in a child?

Foreign body aspiration. **Explanation:** The clinical triad of **acute onset** cough, stridor, and dyspnea in a child is the classic presentation of **Foreign Body Aspiration (FBA)**. In pediatric patients, the sudden nature of symptoms (the "penetration syndrome") is the most critical diagnostic clue. Stridor indicates an upper airway or tracheal obstruction, while wheezing or decreased breath sounds usually suggest a bronchial location. **Why the other options are incorrect:** * **Acute Asthma:** While it presents with cough and dyspnea, it typically manifests as **expiratory wheezing** rather than inspiratory stridor. It is usually preceded by triggers or a known history of atopy and is rarely as instantaneous as FBA. * **Aspiration Pneumonitis:** This involves the inhalation of gastric contents or liquids. While it causes respiratory distress, it usually presents with fever, rales, and signs of inflammation over hours, rather than the sudden mechanical obstruction seen with a solid foreign body. * **Primary Complex (Tuberculosis):** This is a chronic infection. It presents with a persistent cough, low-grade fever, and weight loss over weeks or months, not with acute stridor and sudden dyspnea. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Right main bronchus (due to it being wider, shorter, and more vertical). * **Most common age group:** 1–3 years (toddlers). * **Gold Standard Diagnosis & Management:** Rigid Bronchoscopy (both diagnostic and therapeutic). * **Radiology:** The most common finding is **obstructive emphysema** (air trapping) on expiratory films; however, a normal X-ray does not rule out FBA if clinical suspicion is high.

Question 1

Which of the following statements is true about cystic fibrosis?

Accepted Answer

Immune reactive trypsin may be checked on the Guthrie card.

Answer

The underlying defect is in sodium channel function.

Answer

In most cases, the gene defect is a loss of Valine at position 508 on chromosome 7.

Answer

A sweat test with a sodium content above 40 mmol/l is diagnostic.

Question 2

A child presents with fever and a barky cough. On examination, the respiratory rate is 36/min, stridor is present only on crying, and the temperature is 39 degrees Celsius. There are no other abnormal findings. What is the next logical step in management?

Accepted Answer

Dexamethasone

Answer

Surfactant administration

Answer

Racemized epinephrine nebulization

Answer

Observation and reassurance

Question 3

All of the following are seen in a patient with cystic fibrosis except?

Accepted Answer

Metabolic acidosis

Answer

Hypochloremia

Answer

Recurrent pneumonias

Answer

Steatorrhoea

Question 4

Which of the following is not true about idiopathic pulmonary hemosiderosis?

Accepted Answer

Eosinopenia

Answer

Iron deficiency Anemia

Answer

Increased Bilirubin

Answer

Increased Reticulocyte count

Question 5

Fast breathing in a child less than 2 months is defined as a respiratory rate more than what value?

Accepted Answer

60 breaths per minute

Answer

40 breaths per minute

Answer

50 breaths per minute

Answer

70 breaths per minute

Question 6

How does a child's respiratory physiology differ from that of an adult?

Accepted Answer

Smaller airways

Answer

Increased oxygen demand

Answer

Decreased tidal volume

Answer

Decreased residual volume

Question 7

A neonate presents with respiratory distress, enlargement of the left upper lobe of the lung, and mediastinal shift towards the right. What is the most likely diagnosis?

Accepted Answer

Congenital lobar emphysema

Answer

Alpha 1 antitrypsin deficiency

Answer

Pneumonia

Answer

Cystic fibrosis

Question 8

A 2-year-old female child was brought to a PHC with a history of cough and fever for 4 days and inability to drink for the last 12 hours. On examination, the child weighed 5 kg and had a respiratory rate of 45/minute with fever. How would this child be classified?

Accepted Answer

Very severe disease

Answer

Severe pneumonia

Answer

Pneumonia

Answer

No pneumonia

Question 9

All of the following statements about cystic fibrosis (CF) are true EXCEPT:

Accepted Answer

A high concentration of sodium or chloride in sweat is diagnostic of CF.

Answer

It can cause diarrhea.

Answer

Staphylococcus aureus, Hemophilus influenzae, and Pseudomonas aeruginosa are common causes of respiratory infections.

Answer

Rhinosinusitis is a common finding in CF.

Question 10

What is the most likely cause of acute onset of cough, stridor, and dyspnea in a child?

Accepted Answer

Foreign body aspiration

Answer

Acute asthma

Answer

Aspiration pneumonitis

Answer

Primary complex

Respiratory Diseases — MCQs

Respiratory Diseases — MCQs

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