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Background: Hypoxemia episodes (HE) occur frequently in ventilated preterm infants and hinder the achievement of arterial oxygen saturation (SpO₂) targets. These episodes may increase the risk for retinopathy of prematurity and neurodevelopmental disability. There are no data on the variation in HE and SpO₂ targeting between day and night. Objective: The aim of this study was to evaluate the difference between day and night on the frequency and severity of HE and achievement of SpO₂ targets. Methods: Twenty-four mechanically ventilated preterm infants with ≥4 episodes of SpO₂ <75% over an 8-h period were enrolled. The fraction of inspired oxygen (FiO₂), SpO₂, and ventilator parameters were recorded over 24 h. Data from the day (9 a.m. to 5 p.m.) were compared to the night (9 p.m. to 5 a.m.) for the frequency of HE and proportion of time within and outside the target SpO₂ range (90-95%). Results: The frequency of severe HE (SpO₂ <75, ≥20 s) and prolonged severe HE (SpO₂ <75, ≥60 s) was lower during the night compared to the day (1.6 ± 1.0 vs. 2.4 ± 1.3 episodes/h, p = 0.008, and 0.53 ± 0.35 vs. 0.90 ± 0.54 episodes/h, p = 0.018). There was no difference in mean episode duration. The frequency and duration of mild HE (SpO₂ <85, ≥20 s) were lower during the night compared to the day (5.9 ± 2.7 vs. 7.1 ± 2.5 episodes/h, p = 0.003, and 72 ± 15 vs. 87 ± 25 s, p = 0.01, respectively). The proportion of time in severe hypoxemia (SpO₂ <75%) was smaller, whereas time in hyperoxemia (SpO₂ >95%) was greater, during the night compared to the day. The mean FiO₂ did not differ between day and night. Conclusion: In this group of infants with frequent HE, nighttime was associated with fewer episodes when compared to daytime. This is likely due to less handling and sensory stimulation during the night. The increase in time spent with hyperoxemia during the night is likely to be due to more tolerance of high SpO₂ with less proactive weaning of FiO₂.

Background: Preterm infants on mechanical ventilation have spontaneous hypoxemia episodes (HE) triggered by decreases in lung volume and tidal volume (V_T). Volume guarantee (VG) is a mode where the ventilator peak pressure is adjusted to keep the exhaled V_T at a target level. The effect of VG on HE under routine clinical conditions has not been fully evaluated. Objective: To evaluate the effect of VG on HE in preterm infants in comparison to pressure control (PC) ventilation under routine clinical conditions. Methods: Twenty-four mechanically ventilated preterm infants with ≥4 HE of arterial oxygen saturation (SpO₂) <75% over 8 h were enrolled. They were studied over 2 consecutive 24-hour periods of VG and PC, in random order. Results: While the frequency of HE (SpO₂ <85% for ≥20 s) did not differ, their duration was reduced during VG. The frequency or duration of severe HE (SpO₂ <75% for ≥20 s) did not differ between PC and VG. The proportion of time in severe hypoxemia (SpO₂ <75%) during VG did not differ from PC [median: 4.4 (IQR 2.9-5.0) vs. 5.0% (IQR 3.9-6.9), p = 0.44]. The fraction of inspired oxygen (FiO₂) was lower during VG compared to PC. Conclusion: The use of VG during routine clinical conditions resulted in a modest reduction in the duration of HE (SpO₂ <85%) and FiO₂ compared to PC. The use of VG did not reduce the more severe HE.

Bronchopulmonary dysplasia (BPD) continues to be one of the common complications of premature birth. The paper by Freidman et al in this issue of RESPIRATORY CARE shows the effectiveness of establishing a balanced approach to reduce the exposure to mechanical ventilation, with the ultimate goal of reducing the incidence of BPD in premature infants of very low birth weight. 1 SEE THE ORIGINAL STUDY ON PAGE 1134 As evidenced by the recent trials, a large proportion of infants can be adequately managed with CPAP, with comparable rates of BPD to those achieved in mechanically ventilated infants. 2,3 These trials also made clear that a significant proportion of infants initially started on CPAP eventually require mechanical ventilation, which was more evident among infants of lower gestational age. In the cohort reported by Friedman et al, 60% of VLBW infants required ventilation on day 1, and more than 30% on day 7. Hence, once the infants are intubated and placed on mechanical ventilation, the respiratory care strategy becomes increasingly relevant.In this cohort the proportion of extubation failure in the first era, when ventilator driven CPAP was used, was similar to that in the second era, when bubble CPAP was used after extubation. This is in agreement with existing data from clinical trials that showed none of the CPAP delivery methods offers advantages over the rest in reducing extubation failure. 4,5 To manage ventilated infants, Friedman et al established a combined approach of surfactant administration with immediate extubation (the INSURE strategy) as well as a weaning protocol for rapid extubation to bubble CPAP, and a reintubation protocol for those infants failing extubation. In addition, the authors report an increased use of vitamin A, and reduced rates of ductal ligation in the second era. The authors demonstrate the association between this combined approach and the observed reduction in the duration of mechanical ventilation and the incidence of BPD.Although this study has the known limitations of a retrospective data analysis, it underlines the fact that prevention of BPD requires a multifaceted strategy. This study also reminds us that, following the institution of strategies to improve one outcome, it is prudent to monitor for the occurrence of unexpected increases in morbidities or mortality. Nelson Claure MSc PhD