Which infant is likely to experience the highest insensible water loss?

The infant most likely to experience the highest insensible water loss is the one under an infant warmer. This type of care exposes the infant to increased environmental airflow and is associated with elevated evaporation rates. Infants, particularly those who are preterm or of lower gestational age, have a larger surface area relative to their weight, which contributes to a higher risk of insensible water loss through their skin.

Under an infant warmer, the baby's skin is more directly exposed to heated air, which further increases evaporation. This setting can lead to significant fluid loss, especially in an immature infant whose skin barrier may not be fully developed, making it less effective in retaining moisture.

In contrast, a full-term infant in a crib is typically not at immediate risk for significant insensible water loss as they are in a more enclosed environment. An infant in a closed incubator benefits from a controlled environment that minimizes airflow, further helping to reduce fluid loss. Lastly, while the infant on mechanical ventilation can also have water loss concerns, the use of an incubator or other supportive measures is likely to provide better humidity control and minimize water loss compared to an unshielded warmer.