Estimating the arterial CO2 partial pressure by sensor fusion of end-tidal and transcutaneous CO2 measurements

Closed-loop control of the arterial CO2 partial pressure (PaCO2) could improve respiratory care in preterm neonates but requires an accurate, continuous, and noninvasive surrogate of PaCO2. We propose fusing end-tidal and transcutaneous CO2 measurements to obtain such a signal. We evaluate two fusion approaches: (i) a linear combination of the two measurements and (ii) a state-augmented Kalman filter. Both methods are tested on mechanical ventilation data from five preterm lambs. In this dataset, both fusion approaches improve PaCO2 estimation compared with either end-tidal or transcutaneous CO2 alone, supporting their potential for future closed-loop ventilation systems.