Feeding a patient with respiratory failure is more complicated in a neonatal than in an adult intensive care setting. For adults the goal is to maintain an acceptable energy balance without imposing extra metabolic and respiratory stress on the organism. In newborn infants, the caloric cost for growth has to be added to the energy balance which means that additional respiratory demands will be imposed on the neonate, because the growth process itself produces carbon dioxide and consumes oxygen.
Nutritional status affects the respiratory system directly by providing energy for the respiratory muscles and development of lung structure and function; indirectly, the level of energy intake (EI) and the dietary macronutrient composition modify the metabolic demands and affect the respiratory system by modifying central ventilatory drive and the respiratory gaseous exchange.
This chapter describes the effect of nutrition on the development and function of the respiratory system in newborns. The first portion describes the interactions between nutrition and structural, biochemical, and functional changes in the lung. The second part addresses metabolic needs of infants with acute respiratory distress and describes the effects of EI and/or diet composition on respiratory gas exchange and energy metabolism in intravenously fed neonates.
Nutrition, metabolism, and the respiratory system
Lung development and morphology
The preterm infant with a birth weight of 1000 g has an expendable nonprotein energy reserve of less than 200 kcal, with 1%–2% of the body weight as fat and less than 1% as glycogen.