The mother of an infant with hypertrophic pyloric stenosis asks the nurse many questions about the problem. When answering these questions, the nurse should convey the idea that:

Choice A reason: Somnolence, hypotension, and oliguria are signs of decompensated shock, which occurs when the body's compensatory mechanisms fail to maintain adequate tissue perfusion.

Choice B reason: Irritability, tachypnea, and hypotension are also signs of decompensated shock, as the respiratory rate increases to compensate for the low blood pressure and oxygen delivery.

Choice C reason: Irritability, capillary refill time > 2 seconds, and bradycardia are not typical signs of compensated shock, as the heart rate usually increases to maintain cardiac output and blood pressure.

Choice D reason: Irritability, tachycardia, and poor peripheral perfusion are signs of compensated shock, which occurs when the body tries to maintain adequate tissue perfusion by increasing the heart rate, constricting the peripheral blood vessels, and shunting blood to the vital organs.

Choice A reason: This statement is correct, as asking about the child's contacts over the last three weeks can help the nurse identify the possible source of infection and the risk of transmission. Rubella is a viral infection that spreads through respiratory droplets or direct contact with an infected person. The incubation period of rubella is 14 to 21 days, meaning that the child could have been exposed to the virus up to three weeks before developing symptoms.

Choice B reason: This statement is incorrect, as asking about the child's immunizations is not the most effective way to determine how the child was exposed to the virus. Although immunization can prevent rubella infection, it is not 100% effective, and some children may still get the disease despite being vaccinated. The nurse should also consider other factors, such as the child's medical history, travel history, and exposure to other people with rash or fever.

Choice C reason: This statement is incorrect, as asking about the medications given to the child is not the most effective way to determine how the child was exposed to the virus. Medications can help relieve the symptoms of rubella, such as fever, rash, or joint pain, but they do not affect the transmission or the course of the infection. The nurse should focus on the epidemiological aspects of the disease, such as the mode of transmission, the incubation period, and the contagious period.

Choice D reason: This statement is incorrect, as asking about the onset of the rash is not the most effective way to determine how the child was exposed to the virus. The rash of rubella usually appears 14 to 17 days after exposure, and lasts for about three days. However, the child can be contagious from seven days before to seven days after the rash appears, meaning that the child could have been exposed to the virus up to four weeks before or after the rash. The nurse should ask about the child's contacts during this period, not just the rash.