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

Abstract

Background: Mechanically ventilated very low birth weight infants often present with frequent episodes of hypoxemia, and maintaining arterial oxygen saturation by pulse oximetry (SpO(2)) within a normal range by manual fraction of inspired oxygen (FIO(2)) adjustments is difficult and time consuming.

Objectives: An algorithm for closed-loop FIO(2) control (cFIO(2)) to maintain SpO(2) within a target range was compared with continuous manual FIO(2) (mFIO(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 ventilation 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 for 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) during 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 were 13 +/- 10 and 10 +/- 8 hyperoxemic episodes/hour (SpO(2)>96%, >5 s) during mFIO(2) and cFIO(2,) respectively; episode duration was 27 +/- 15 and 24 +/- 19 s, totaling 15 +/- 14% and 10 +/- 9% of recording time. Mean SpO(2) and FIO(2) levels were similar during both modes. The nurse made 29 +/- 17 adjustments/hour during mFIO(2). There was a significant increase in the duration 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 reduce the risks of morbidity associated with supplemental oxygen and episodes of hypo- and hyperoxemia.