This contract would develop three devices and techniques that would then be tested and evaluated for neonatal and pediatric applications. The following development and evaluation projects are included: a flow-through mask system that fits on the child's or infant's face with a pneumotachygraph on the inspiratory as well as the expiratory line so that inhaled and exhaled flow rates, gas concentrations, ventilation, oxygen uptake and CO production can be measured; an intercostal retraction meter, which is a small negative pressure chamber fitting into the intercostal and to measure the reflected pleural pressures; and sensor for a noninvasive blood gas measurement using a mass spectrometer. These basic measurements will be used to measure pulmonary resistance, lung compliance, lung volumes by gas dilution, and output by gas dilution of a soluble and insoluble gas.