The nurse is conducting an admission assessment of an infant with heart failure who is scheduled for repair of restenosis of coarctation of the aorta that was repaired 4 days after birth. Findings include blood pressure higher in the arms than the lower extremities, pounding brachial pulses, and slightly palpable femoral pulses. Which pathophysiologic mechanism supports these findings?

Choice A reason: Taking the child to a hair salon for a shampoo and a shorter haircut is not a good instruction that the nurse should provide. This is because a hair salon may not accept a child with head lice, as they can spread to other customers and staff. A shorter haircut may also not help to get rid of the lice or their eggs, which can attach to any length of hair.

Choice B reason: Rewashing the child's hair following a 24-hour isolation period is not a good instruction that the nurse should provide. This is because a 24-hour isolation period is not necessary or effective for treating head lice. Head lice do not survive long without a human host, and they do not spread through the air or by jumping. Rewashing the child's hair may also wash off the permethrin shampoo, which needs to stay on the hair for 10 minutes to kill the lice and their eggs.

Choice C reason: Washing the child's bed linens and clothing in hot soapy water is a good instruction that the nurse should provide. This is because head lice and their eggs can be transferred to the child's bedding and clothing through direct contact. Washing these items in hot water (at least 130°F or 54°C) and drying them on high heat can kill any remaining lice or eggs. Alternatively, the items can be sealed in plastic bags for two weeks to suffocate the lice.

Choice D reason: Disposing of the child's brushes, combs, and other hair accessories is not a good instruction that the nurse should provide. This is because it is not necessary to throw away these items, as they can be treated and reused. The nurse should advise the parents to soak the items in hot water (at least 130

Choice A reason: The lumen of the aorta reduces the volume of blood flow to the lower extremities is the correct pathophysiologic mechanism that supports the findings. This is because coarctation of the aorta is a congenital condition that causes a narrowing of the aorta, usually near the ductus arteriosus. This results in increased resistance to blood flow from the heart to the lower body, leading to higher blood pressure and stronger pulses in the upper extremities and lower blood pressure and weaker pulses in the lower extremities.

Choice B reason: The aortic semilunar valve obstructs blood flow into the systemic circulation is not the correct pathophysiologic mechanism that supports the findings. This is because the aortic semilunar valve is located at the base of the aorta and prevents blood from flowing back into the left ventricle. If the valve is obstructed, it would cause aortic stenosis, which is a different condition from coarctation of the aorta. Aortic stenosis would cause symptoms such as chest pain, shortness of breath, and fainting.

Choice C reason: The pulmonic valve prevents adequate blood volume into the pulmonary circulation is not the correct pathophysiologic mechanism that supports the findings. This is because the pulmonic valve is located at the base of the pulmonary artery and prevents blood from flowing back into the right ventricle. If the valve is obstructed, it would cause pulmonic stenosis, which is a different condition from coarctation of the aorta. Pulmonic stenosis would cause symptoms such as cyanosis, fatigue, and heart murmur.

Choice D reason: An opening in the atrial septum causes a murmur due to a turbulent left to right shunt is not the correct pathophysiologic mechanism that supports the findings. This is because an opening in the atrial septum is a defect in the wall that separates the two upper chambers of the heart. It would cause a condition called atrial septal defect, which is different from coarctation of the aorta. Atrial septal defect would cause symptoms such as difficulty breathing, frequent respiratory infections, and heart palpitations.