Rapid and deep breathing without other signs of respiratory distress may be caused by the following EXCEPT:

Correct Answer: C

Rationale: Rapid, deep breathing (Kussmaul breathing) is typically associated with diabetic ketoacidosis, renal tubular acidosis, and CNS stimulants. Heart failure typically causes shallow, labored breathing, not deep breathing without distress.

Correct Answer: D

Rationale: The overall incidence of multifetal gestation has increased due to assisted reproductive technologies. The other statements are true regarding multiple gestation pregnancies.

Correct Answer: D

Rationale: Vitamin A supplementation reduces BPD and sepsis but does not significantly impact the need for ECMO. The other options are benefits of vitamin A supplementation.

Correct Answer: A

Rationale: Methotrexate primarily works by suppressing the immune system, reducing inflammation in rheumatoid arthritis.

Correct Answer: D

Rationale: Major depression in children can have a genetic basis, may start before adolescence, and carries risks for future depressive episodes. Hallucinations are uncommon but possible.

Correct Answer: B

Rationale: The steeple sign, seen on X-ray, is a hallmark of viral croup, indicating subglottic airway narrowing.

Correct Answer: D

Rationale: Major depression in children can have a genetic basis, may start before adolescence, and carries risks for future depressive episodes. Hallucinations are uncommon but possible.

Correct Answer: C

Rationale: The anion gap is calculated as (Na⁺ - [Cl⁻ + HCO₃⁻]) and represents unmeasured anions in plasma. It helps differentiate metabolic acidosis causes, with high values suggesting lactic acidosis or toxin ingestion.

Correct Answer: C

Rationale: Theophylline toxicity is likely due to the interaction with erythromycin/sulfisoxazole, which inhibits theophylline metabolism.