1. Premature infants and neonates \< 37 weeks corrected gestational age,

2. Transfer patient on an established enteral or parenteral nutritional regimen,

3. Known allergy to lactulose or mannitol,

4. Pregnant,

5. Admit BMI \>30,

6. Thoracic trauma, abdominal trauma, and/or active intracranial bleeding,

7. Anuric renal failure, previous bowel surgery and/or short gut syndrome,

8. Cannot be enterally fed within 24 hours of admission according to the admitting physician,

9. On extracorporeal membrane oxygenation (ECMO),

10. Expected survival \<24 hours or limitations to aggressive ICU care (DNR),

11. Receiving active CPR when admitted to the PICU,

12. A pre-existing bronchopleural fistula,

13. Previously enrolled and randomized into this protocol,

14. Actively enrolled in another clinical trial which at the discretion of the PI would conflict with this study.

Supplemental Parenteral Nutrition in Pediatric Respiratory Failure