In contemporary transfusion practice, the commonest cause of life threatening reaction is:

Correct Answer: C

Rationale: ABO incompatibility (C) is the commonest life-threatening transfusion reaction mismatched antigens (e.g., A to O) cause acute hemolysis (e.g., Hb drop, renal failure), with 1:40,000 risk. Contamination (A) is rare with screening. Rh (B) or WBC reactions are milder. Allergy (D) is non-hemolytic. ABO's severity is key, guiding nursing for crossmatch checks and reaction management.

Correct Answer: A

Rationale: Stage I Hodgkin's single node region treats with intensive irradiation (A e.g., 36 Gy), curing 90% by targeting lymphoma (e.g., mantle field). Surgery (B) is diagnostic. Chemo (C) is for advanced stages. None' (D), transfusion unfit. Radiation's efficacy is key, guiding nursing for planning and skin care.

Correct Answer: C

Rationale: Gold therapy (e.g., aurothiomalate) for rheumatoid arthritis common toxicities are dermatitis and stomatitis (C e.g., rash, mouth sores in 20-40%), from hypersensitivity. Nausea (A), agranulocytosis (B), thrombophlebitis (D), alopecia are rarer. Skin/mucosal effects are key, guiding nursing for monitoring and discontinuation.

Correct Answer: B

Rationale: Infant respiratory distress syndrome (IRDS), or hyaline membrane disease, occurs in premature infants due to insufficient surfactant production by immature type II alveolar cells. Surfactant lowers alveolar surface tension (T), facilitating lung expansion. In IRDS, reduced surfactant leads to increased surface tension, causing alveoli to collapse (atelectasis) after each breath. This high tension decreases lung compliance (C), as the lungs become stiffer and harder to inflate, requiring greater pressure for ventilation. Consequently, collapsed alveoli impair gas exchange, reducing arterial oxygen partial pressure (PaO2) below normal (hypoxemia), often to levels like 50-60 mmHg instead of the typical 75-100 mmHg. The correct combination increased T, decreased C, decreased PaO2 reflects the pathophysiology of IRDS, where surfactant deficiency drives a cascade of respiratory challenges. Other combinations, like increased compliance or unchanged PaO2, contradict the condition's mechanics, where stiff lungs and poor oxygenation are hallmark features.

Correct Answer: A

Rationale: The volume of air entering the lung during inspiration is driven by Boyle's law: lung volume increases as intrapulmonary pressure decreases relative to atmospheric pressure. This pressure gradient is created by the diaphragm and intercostal muscles contracting, expanding the thoracic cavity, and dropping intrapulmonary pressure (e.g., from 760 mmHg to 758 mmHg), allowing air to flow in. Increasing this gradient via greater muscle contraction or thoracic expansion directly increases inspired volume, making it the primary factor. Increase in action potential' is vague but likely refers to neural impulses to respiratory muscles; while more frequent or intense action potentials could enhance muscle effort, this is secondary to the mechanical pressure gradient they produce. Combining both doesn't elevate action potentials to equal status, as pressure is the direct mechanism. Decreasing the gradient reduces airflow, opposing the goal. Thus, the pressure gradient is the most critical factor, as it's the physical driver of ventilation, rooted in respiratory mechanics.