Final answer:
An 18-month-old child who has been vomiting should be placed in a supine position during sleep to minimize the risk of aspiration and follow safe sleep practices.
Step-by-step explanation:
A nurse caring for an 18-month-old child who has been vomiting should place the child in a supine position (on their back) during naps and sleep time to minimize the risk of aspiration, which can occur if the child vomits while lying on their stomach or side.
This positioning advice aligns with research on the prevention of Sudden Infant Death Syndrome (SIDS) and is considered a safe sleep practice for infants and toddlers. It is crucial to also ensure that the child's sleep environment is free of potential suffocation hazards such as blankets, pillows, and padded crib bumpers.