OBJECTIVES:

I. Determine the total energy expenditure in term and preterm infants in both well and ill states using the doubly labeled water method.

PROTOCOL OUTLINE: Patients are assigned to one of three groups according to gestational age (24-28 weeks estimated gestational age (EGA) vs 29-34 weeks EGA vs 35 weeks EGA and over) and severity of respiratory illness (need for high frequency ventilation vs stable conventional ventilator settings or extubated within past 24 hours vs no need for mechanical ventilation).

Patients receive water labeled with deuterium and oxygen O 18 by mouth or by gastrostomy tube on days 1 and 7. Urine samples are collected prior to the first dose, 4-6 hours after the first dose, and then every 24 hours until the second dose. All urine is collected for 4-6 hours after the second dose. Samples are analyzed by dual inlet isotope ratio mass spectrometry.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics--

Infants with estimated gestational age (EGA) of at least 24 weeks with respiratory illness who are on high frequency ventilation (HFOV) and meet the following conditions: Appropriate size for gestational age (AGA) No congenital anomalies No medical complications, including seizures and necrotizing enterocolitis

OR

Control infants with EGA of at least 24 weeks Must meet 1 of the following conditions: Requirement for stable conventional ventilator settings with respiratory index score of less than 2.5 and/or extubated within past 24 hours No requirement for mechanical ventilation Must meet all of the following conditions: AGA No congenital anomalies No medical complications, including seizures and necrotizing enterocolitis No documented sepsis by positive blood culture No supplemental oxygen use (infants 35 weeks EGA and over only)

--Prior/Concurrent Therapy--

HFOV group: Concurrent surfactant, theophylline, or inotrope (vasopressor) therapy allowed

Control group: No concurrent inotrope (vasopressor) therapy