Closed-Loop Controlled Inspired Oxygen Concentration for Mechanically Ventilated Very Low Birth Weight Infants With Frequent Episodes of Hypoxemia

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Abstract
Background. Mechanically ventilated very low birth weight infants often present with frequent episodes of hypoxemia, and maintaining arterial oxygen saturation by pulse oximetry (Spo2) within a normal range by manual fraction of inspired oxygen (Fio2) adjustments is difficult and time consuming. Objectives. An algorithm for closed-loop Fio2 control (cFio2) to maintain Spo2 within a target range was compared with continuous manual Fio2(mFio2) 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 cmH2O; positive end-expiratory pressure: 4.3 ± 0.5 cmH2O) were studied for 2 hours on each mode in random sequence. Both modes aimed to maintain Spo2 between 88% and 96%. There were 15 ± 7 and 16 ± 6 hypoxemic episodes/hour (Spo2 5 s) during mFio2 and cFio2, 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 (Spo2>96%, >5 s) during mFio2 and cFio2,respectively; episode duration was 27 ± 15 and 24 ± 19 s, totaling 15 ± 14% and 10 ± 9% of recording time. Mean Spo2 and Fio2 levels were similar during both modes. The nurse made 29 ± 17 adjustments/hour during mFio2. There was a significant increase in the duration of normoxemia (Spo2 between 88%–96%) during cFio2 (75 ± 13 vs 66 ± 14% of recording time). Conclusion. In this group of infants, cFio2 was at least as effective as a fully dedicated nurse in maintaining Spo2 within the target range, and it may be more effective than a nurse working under routine conditions. We speculate that during long-term use, cFio2 may save nursing time and reduce the risks of morbidity associated with supplemental oxygen and episodes of hypo- and hyperoxemia.