59 3 Comparison of two devices for automated oxygen control in preterm infants Histograms of pooled SpO2 data from the two automated control periods are shown in Figure 2, demonstrating a narrower SpO2 distribution and a lower median SpO2 during OxyGenie control resulting in a higher proportion of time within the SpO2 TR. On per patient analysis, for the study primary outcome there was a 11.7% increase in time within the SpO2 TR during oxygen control with the OxyGenie algorithm when compared to the CLiO2 device (Table 2). Twelve infants spent more time in TR with OxyGenie control, and three with CLiO2 control (Figure 3). During the OxyGenie period, less time was spent above the TR while in supplemental oxygen, but more time spent below TR. SpO2 values <80% were very infrequent throughout the study, and the time with SpO2 <80% did not differ between control devices. The coefficient of variation for SpO2 was similar for both devices (3.3% (2.6% - 4.0%) vs 3.2% (3.0% – 3.4%), p = 0.82). Table 2. Proportions of time within SpO2 ranges Oxygenie CLiO2 p Value* Time SpO2 in target range† 80.2 (72.6 – 82.4) % 68.5 (56.7 – 79.3) % 0.005 Time SpO2 < target range 14.7 (11.8 – 17.2) % 9.3 (8.2 – 12.6) % 0.020 Time SpO2 > target range‡ 6.3 (5.1 – 9.9) % 15.9 (11.5 – 30.7) % 0.001 SpO2 85% - 90% 12.6 (10.9 – 13.1) % 8.5 (7.6 – 11.0) % 0.020 SpO2 80% - 84% 1.2 (0.7 – 3.0) % 0.8 (0.5 – 0.9) % 0.003 SpO2 < 80% 0.5 (0.1 – 1.0) % 0.2 (0.1 – 0.4) % 0.061 SpO2 96% - 98% & FiO2 >= 0.22 6.1 (5.0 – 9.5) % 15.5 (10.9 – 27.4) % 0.001 SpO2 > 98% & FiO2 >= 0.22 0.2 (0.1 – 0.4) % 1.4 (0.4 – 3.7) % 0.001 Data in median (IQR). * Wilcoxon matched pairs test. † 91% <= SpO2 <= 95% or SpO2 >= 96% while FiO2 = 0.21. ‡ SpO2 >= 96% while FiO2 >= 0.22 There was a decrease in frequency of both hypoxaemic and hyperoxaemic episodes during OxyGenie control (Table 3). Bradycardic episodes (<100 bpm for ≥10 seconds) were rare in both epochs and were not different (0.3 (0.1 - 0.6) vs 0.2 (0.0 – 0.5) per hour, p = 0.22).
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