Pleural friction rub is characterized by all the following EXCEPT:

Correct Answer: A

Rationale: Pleural friction rub is typically heard throughout both inspiration and expiration. It is caused by inflamed pleural surfaces rubbing together and may disappear when fluid accumulates.

Correct Answer: A

Rationale: True umbilical cord knots are more likely to occur with long cords and are not associated with short cords. The other conditions can increase the risk of cord knots.

Correct Answer: B

Rationale: Epinephrine is the first-line treatment for anaphylaxis because it rapidly reverses bronchoconstriction, vasodilation, and hypotension.

Correct Answer: C

Rationale: Severe aortic stenosis impairs cardiac output, leading to reduced perfusion and obstructive shock, unlike conditions like myocarditis or dehydration.

Correct Answer: B

Rationale: Inhaled short-acting beta-agonists (SABAs) are the first-line treatment for acute asthma exacerbations, providing rapid bronchodilation.

Correct Answer: D

Rationale: Mixed cellularity Hodgkin lymphoma is the most common subtype in children and is associated with Epstein-Barr virus. It presents with widespread lymphadenopathy and systemic symptoms. Nodular sclerosis is more common in adolescents and young adults.

Correct Answer: B

Rationale: Anaphylactoid purpura (Henoch-Schanlein purpura) is the most common cause of non-thrombocytopenic purpura in children, characterized by a small-vessel vasculitis leading to purpuric rash, arthritis, and renal involvement.

Correct Answer: C

Rationale: Phototherapy is the first-line treatment for neonatal jaundice to prevent bilirubin-induced neurotoxicity (kernicterus). It converts unconjugated bilirubin into a water-soluble form for excretion.

Correct Answer: A

Rationale: Preterm infants have underdeveloped lungs, and mechanical ventilation or high oxygen pressure can lead to alveolar rupture, causing air to accumulate in the pleural space (pneumothorax), leading to respiratory distress.