Is expiation obligatory upon a deputy intensive care physician who unintentionally caused the death of an infant, despite the presence of a pediatrician who provided no guidance?

If the doctor is certain or believes it most likely that the infant's death was due to his error in prescribing the medication or estimating its dosage, then this falls under accidental killing (qatl al-khata'), and he is liable for expiation (kaffarah), and his 'aqilah (male relatives on the paternal side) are liable for the blood money (diyah).