157 9 General discussion and future perspectives to consent to this procedure. Finally, the respiratory condition of the infant under study may change rapidly due to unforeseen events such as sepsis, meaning the time window in which such a study can be done is short. In the LUMC we were in the unique situation that caregivers were trained to work with the AVEA system, which incorporates the CLiO2 controller, and at the same time in the process of acquiring and training caregivers for SLE6000 ventilators. In chapter 3 we describe a crossover study comparing the OxyGenie and CLiO2 algorithm in preterm infants. We observed that OxyGenie was better at maintaining oxygen saturation within the target range, preventing hyperoxaemia and severe hypoxaemia. This was accompanied by an increase in overall mild hypoxaemia during OxyGenie control. The OxyGenie algorithm appeared more responsive, as 30 second and 60 second deviations from the target range were less frequent, indicating that although infants may venture under the target range more frequently during OxyGenie control, they did return to the target range more promptly than during CLiO2 control. These results make it apparent that choice of algorithm, with its inherent design and responsiveness, will largely influence the success of SpO2 targeting. For this thesis, the first head-to-head comparison between two different ventilators incorporating AOC algorithms was performed. Achieved proportions of time within target range were similar to other studies when either OxyGenie or CLiO2 was compared against manual control.18, 20, 22-29 There were two previous studies that compared an updated version of an AOC algorithm (CLACfast versus CLACslow 17, SPOCnew versus SPOCold 30), rather than two different algorithms, in a crossover study. In both studies the update changed the responsiveness in a way, mostly making them act quicker in the case of target range deviations. While no significant differences between algorithm versions were found, superiority of automated oxygen control was demonstrated when compared to manual titration. The mild increase in time under target range during OxyGenie control was unexpected. Explaining this finding is hampered by limited availability of data on the exact working of the CLiO2 algorithm, but it may be related to a higher median SpO2 achieved during CLiO2 control. A higher median SpO2 corresponds to a more gradual part of the oxygen-haemoglobin dissociation curve.31 On a more gradual slope, a change in partial pressure of oxygen will have a smaller effect on the oxygen saturation, possibly resulting in a more stable oxygen saturation. Indeed, this could explain the experience of our nurses finding preterm infants’ oxygen saturation more stable when a slightly higher saturation is accepted. The relevance of higher median
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