Respiratory Heat and Water Loss in Neonates. Volume 1

摘要

A thermodynamic analysis of the energy exchange during respiration identifies the mathematical equations and physiological parameters used in the calculation of respiratory heat loss. An instrumentation system was developed to measure the respiratory gas temperatures, volumetric flow rates and concentrations of oxygen, carbon dioxide and water vapor. Extensive testing of the system was performed to establish safe and accurate data collection procedures; the data analysis techniques used with each type of measurement transducer were developed from experimental evaluations. The thermal state of the infant was evaluated during the respiratory heat loss measurement. The thermal state is defined in terms of the magnitudes and fluctuations of 6 selected skin surface temperatures, the body core temperature and the environmental air temperature. Respiratory heat loss data has been collected from healthy inborn infants. Five respiratory heat loss studies have been analyzed, four of which were conducted on infants between the ages of 11 and 20 hours. The respiratory heat loss measurements from one infant were repeated during the fourth day of life. The results of the analysis of the respiratory heat loss studies are tabulated for total, sensible and insensible heat loss. Respiratory water loss was computed as was the concentration of oxygen, carbon dioxide and water vapor in the expired gas.