Closed-loop controlled inspired oxygen concentration for mechanically ventilated very low birth weight infants with frequent episodes of hypoxemia

Background. Mechanically ventilated very low birth weight infants often pre sent with frequent episodes of hypoxemia, and maintaining arterial oxygen s aturation by pulse oximetry (SpO(2)) within a normal range by manual fracti on of inspired oxygen (FIO2)adjustments is difficult and time consuming. Objectives. An algorithm for closed-loop FIO2 control (cFIO(2)) to maintain SpO(2) within a target range was compared with continuous manual FIO2 (mFI O(2)) adjustments by a nurse in a group of ventilated infants who presented with frequent episodes of hypoxemia. Results. Fourteen infants (birth weight: 712 +/- 142 g; gestational age: 25 +/- 1.6 weeks; age: 26 +/- 11 days; synchronized intermittent mandatory ve ntilation rate: 24 +/- 10 b/m; peak inspiratory pressure: 17.5 +/- 2.0 cmH( 2)O; positive end-expiratory pressure: 4.3 +/- 0.5 cmH(2)O) were studied fo r 2 hours on each mode in random sequence. Both modes aimed to maintain SpO (2) between 88% and 96%. There were 15 +/- 7 and 16 6 hypoxemic episodes/hour (SpO(2) <88%, >5 s) du ring mFIO(2) and cFIO(2), respectively; episode duration was 41 +/- 23 and 32 +/- 15 s, totaling 19 +/- 16% and 17 +/- 12% of recording time. There we re 13 +/- 10 and 10 +/- 8 hyperoxemic episodes/hour (SpO(2) >96%, >5 s) dur ing mFIO(2) and cFIO(2), respectively; episode duration was 27 +/- 15 and 2 4 +/- 19 s, totaling 15 +/- 14% and 10 +/- 9% of recording time. Mean SpO(2 ) and FIO2 levels were similar during both modes. The nurse made 29 +/- 17 adjustments/hour during mFIO(2). There was a significant increase in the du ration of normoxemia (SpO(2) between 88%-96%) during cFIO(2) (75 +/- 13 vs 66 +/- 14% of recording time). Conclusion. In this group of infants, cFIO(2) was at least as effective as a fully dedicated nurse in maintaining SpO(2) within the target range, and it may be more effective than a nurse working under routine conditions. We speculate that during long-term use, cFIO(2) may save nursing time and redu ce the risks of morbidity associated with supplemental oxygen and episodes of hypo- and hyperoxemia.