Correct Answer: B

Rationale: Chest tubes are necessary after open-heart surgery to facilitate the drainage of air and fluid from the chest cavity. These tubes help prevent complications such as pneumothorax (accumulation of air in the pleural space) or cardiac tamponade (build-up of fluid in the pericardial sac), which can be serious postoperative issues. Options A, C, and D are incorrect because chest tubes are primarily used for draining purposes and not for increasing tidal volumes, maintaining positive intrapleural pressure, or regulating pressure on the pericardium and chest wall.

Correct Answer: D

Rationale: The correct answer is D. Infants have a higher extracellular fluid requirement per unit of body weight, making them more susceptible to dehydration and electrolyte imbalances during illnesses such as diarrhea. Choice A is incorrect because cellular metabolism being unstable is not the primary explanation for the symptoms described. Choice B is incorrect as the proportion of water in the body alone does not fully explain the increased risk of dehydration in infants. Choice C is incorrect because while renal function is immature in children, it is not the most relevant factor in this scenario compared to the increased fluid requirements.

Correct Answer: A

Rationale: The correct answer is A: 'On the back, lying flat'. Placing infants on their back to sleep is recommended to reduce the risk of sudden infant death syndrome (SIDS). This position helps ensure the baby's airway remains clear and reduces the likelihood of suffocation. Choices B, C, and D are not as safe as placing the infant on their back, as they may increase the risk of accidental suffocation or SIDS.

Correct Answer: A

Rationale: The primary goal of therapy during the acute phase of Kawasaki disease is to prevent coronary artery aneurysms. Kawasaki disease is characterized by systemic vasculitis and the most serious complication is the development of coronary artery aneurysms. While reducing fever and improving cardiac function are important aspects of managing Kawasaki disease, the primary focus in the acute phase is to prevent the development of coronary artery aneurysms. Preventing dehydration is also essential but not the primary goal in managing Kawasaki disease.

Correct Answer: A

Rationale: Von Bertalanffy's general system theory applied to families emphasizes the family as a system with interdependent, interacting parts that endure over time to ensure the survival, continuity, and growth of its components. This perspective views the family as a dynamic entity where each member's actions and behaviors impact the overall functioning of the family unit. Choice B is incorrect because it focuses more on the social aspects of family structure rather than the systemic view provided by Von Bertalanffy's theory. Choice C is incorrect as it pertains more to the family life cycle theory, which is different from the general system theory. Choice D is incorrect as it addresses stress response within families, a concept not central to Von Bertalanffy's general system theory.