You are the nurse in a pediatrician’s office. You are taking vital signs of a child who was in the hospital for pertussis last month. The child is unvaccinated. The mother asks, “Now that he has had pertussis, is he immune to it?” The best response from the nurse would be:

Choice A reason: Liver and kidney function do not significantly differ in lead metabolism between young and older children. Lead is stored in bones and tissues, and all children are susceptible to toxicity. The older child’s lower exposure, not stronger organs, explains the difference, making this an incorrect explanation.

Choice B reason: There is no evidence that some children metabolize lead better after exposure. Lead absorption and toxicity depend on exposure, not individual metabolic differences. Younger children’s behaviors increase exposure risk, making this a vague and scientifically inaccurate explanation for the observed difference in lead levels.

Choice C reason: Assuming the older child had elevated lead levels earlier without evidence is speculative. Lead levels persist without intervention, and the older child’s normal levels likely reflect lower exposure due to behavior, not recovery, making this an incorrect and unsupported explanation for the mother.

Choice D reason: Younger children (7 months, 4 years) engage in floor play and hand-to-mouth behaviors, increasing ingestion of lead from dust or objects in contaminated environments. Older children (9 years) are less likely to exhibit these behaviors, reducing exposure, making this the correct and most accurate explanation.

Choice A reason: Holding the child’s arms down while in the crib may increase distress and resistance in an 18-month-old with RSV, who is already agitated. This approach disregards developmental needs for comfort, potentially worsening anxiety and making the exam more difficult, rendering it an ineffective strategy.

Choice B reason: Holding the 18-month-old on the mother’s lap provides comfort, reducing anxiety and resistance during the exam. This developmentally appropriate approach leverages the child’s trust in the caregiver, facilitating cooperation and effective assessment of respiratory status in RSV, making it the best response.

Choice C reason: Delaying the exam until later risks missing critical changes in the child’s respiratory status, as RSV can cause rapid deterioration in young children. Immediate assessment is necessary, and postponing does not address the mother’s distress or the child’s needs, making this an inappropriate response.

Choice D reason: Stating that restraining in the crib is the only way ignores developmental considerations for an 18-month-old. Comforting the child on the mother’s lap is a viable alternative that reduces distress and facilitates the exam, making this an incorrect and inflexible response to the situation.