Fuzzy oxygen control system for the indirect calorimeter of premature infants.

The indirect calorimetric system of measuring O2 consumption and CO2 production has been developed for energy expenditure estimation of premature infants. This apparatus requires an input room air mixing with pure oxygen to obtain a stable gas with definite oxygen concentration flowing into the hood for neonatal breath or supplemental oxygen treatments. In this paper, we propose an oxygen control system based on fuzzy control logic to automatically adjust the mixing ratio of room air to pure oxygen gas from the hospital's supply system, designed for premature infants. It is designed to reduce the risks of oxygenic toxicity and retinopathy of prematurity by lowering the overshoot of oxygen concentration. Its performance was evaluated and optimal membership functions were obtained. As a result, the system is quite robust with little effect caused by disturbance and has little or no overshoot when step changing the level of oxygen concentration in the mixed gas.