Neonatal automated oxygen titration algorithms: response characteristics and performance
Hylke H Salverda, Christoph E Schwarz, Andrew P Marshall, Zeke P Hausmann, Timothy J Gale, Christian F Poets, Nelson Claure, Tom G Goos, Helmut D Hummler, Charles C Roehr, Tomasz Szczapa, Arjan B te Pas, Peter A DargavilleObjective
Neonatal respiratory support devices now have algorithms for automated adjustment of oxygen concentration (fraction of inspired oxygen (FiO 2 )) in response to oxygen saturation (SpO 2 ) disturbances, but their performance has not been systematically examined. We investigated the response of six available devices and algorithms to standardised and simulated SpO 2 disturbances.
Design
Bench-top study in neonatal centres.
Methods
Devices under study received SpO 2 input from a vital signs simulator at 1 Hz; device response was recorded as measured FiO 2 in the respiratory circuit. Response to protracted hypoxaemia (SpO 2 =80%) and hyperoxaemia (SpO 2 =98%) was examined in several test conditions. In closed-loop testing, measured FiO 2 was combined with abstracted patient data in an oxygenation simulator, generating novel SpO 2 values input to the device. Device capability in keeping simulated SpO 2 in target range (91–95%) was examined, as was FiO 2 adjustment frequency and propensity for FiO 2 oscillation.
Results
The FiO 2 trajectories in response to SpO 2 disturbances differed considerably between devices. Maximum rate of sustained FiO 2 escalation (ΔFiO 2 /min) during hypoxaemia was Avea: 0.30; Fabian: 0.20; Leoni: 0.20; SLE: 0.10; Sophie: 0.062; Vapotherm: 0.30. Corresponding values for FiO 2 reduction during hyperoxaemia were 1.20, 0.20, 0.20, 0.13, 0.53 and 1.32. In closed-loop testing, average SpO 2 target range time proportion was 51%, 52%, 55%, 77%, 64% and 53% for the six devices, respectively, with 1.9–5.1 automated FiO 2 adjustments/min, in some cases with a prominent oscillatory pattern.
Conclusions
Automated oxygen control devices exhibit considerable variation in their FiO 2 response to SpO 2 disturbances, with important consequences for SpO 2 targeting potential and the pattern of FiO 2 adjustment.