Is faster better? A randomised crossover study comparing algorithms for closed-loop automatic oxygen control

Objective Closed-loop automatic control (CLAC) of the fractional inspired oxygen (FiO(2)) improved oxygen administration to preterm infants on respiratory support. We investigated whether a revised CLAC algorithm (CLAC(fast), <= 2 FiO(2) adjustments/min), compared with routine manual control (RMConly), increased the proportion of time with arterial haemoglobin oxygen saturation measured by pulse oximetry within prespecified target ranges (Target%) while not being inferior to the original algorithm (CLAC(slow): <= 0.3 FiO(2) adjustments/min). Design Unblinded randomised controlled crossover study comparing three modes of FiO(2) control in random order for 8 hours each: RMC supported by CLAC(fast) was compared with RMConly and RMC supported by CLAC(slow). A computer-generated list of random numbers using a block size of six was used for the allocation sequence. Setting Two German tertiary university neonatal intensive care units. Patients Of 23 randomised patients, 19 were analysed (mean +/- SD gestational age 27 +/- 2 weeks; age at randomisation 24 +/- 10 days) on non-invasive (n=18) or invasive (n=1) respiratory support at FiO(2) >0.21. Main outcome measure Target%. Results Mean +/- SD [95% CI] Target% was 68%+/- 11% [65% to 71%] for CLAC(fast) versus 65%+/- 11% [61% to 68%] for CLAC(slow) versus 58%+/- 11% [55% to 62%] for RMConly. Prespecified hypothesis tests of: (A) superiority of CLAC(fast) versus RMConly and (B) non-inferiority of CLAC(fast) versus CLAC(slow) with margin of 5% yielded one-sided p values of <0.001 for both comparisons. Conclusions This revised and faster CLAC algorithm was still superior to routine care in infants on respiratory support and not inferior to a previously tested slower algorithm.