Which system is best for achieving a precise high FIO2 and maintaining a neutral thermal environment?

The best choice for achieving a precise high fractional inspired oxygen (FIO2) while maintaining a neutral thermal environment is the option that combines an oxy-hood with a warmed oxygen blending system without an incubator.

An oxy-hood provides a controlled and enclosed environment for delivering oxygen, which helps in accurately achieving the desired FIO2 levels. The addition of a warming system helps maintain the infant's body temperature, creating a neutral thermal environment essential for newborns, particularly those who are premature or have difficulty maintaining their own temperature. This option allows for precise regulation of both temperature and oxygen concentration without the confounding effects that an incubator might introduce.

The other options may not achieve this balance as effectively. For example, while incubators are excellent for maintaining temperature, they can complicate the precise delivery of FIO2 due to the enclosed nature and variable oxygen concentrations that can occur inside. Thus, the oxy-hood paired with a warmed blending system is preferred for these specific therapeutic needs.