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Intermittent hypoxemia (IH) events are common during early postnatal life, particularly in preterm infants. These events have been associated with multiple morbidities, including retinopathy of prematurity, sleep disordered breathing, neurodevelopmental impairment, and mortality. The relationship between IH and poor outcomes may depend on the patterns (frequency, duration, and timing) of the IH events. Current treatment modalities used in the clinical setting have been only partially successful in reducing the incidence of apnea and accompanying IH, but the risks and benefits of more aggressive interventions should include knowledge of the relationship between IH and morbidity., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Extremely premature infants are at risk for childhood wheezing. Early respiratory support and intermittent hypoxemia (IH) events may be associated with adverse breathing outcomes., Study Design: A single-center retrospective cohort study of 137 premature infants <28 weeks gestational age characterized the associations of cumulative oxygen, cumulative mean airway pressure, IH, and oxygen saturation (SpO 2 ) on the primary outcome of prescription asthma medication use at 2-year follow-up. Relative risk was calculated by generalized estimating equations., Results: Reported asthma medication use was 46%. At 1-3 days of age, elevated cumulative oxygen exposure, increased daily IH, and lower mean SpO 2 (adjusted for gestational age and sex) and increased cumulative mean airway pressure exposure (unadjusted) were associated with asthma medication use., Conclusion: Increased oxygen and frequent IH events during just the first 3 days of age may help identify extremely premature newborns at risk for symptomatic childhood wheezing requiring prescription asthma medications.

Stabilization of respiration and oxygenation continues to be one of the main challenges in clinical care of the neonate. Despite aggressive respiratory support including mechanical ventilation, continuous positive airway pressure, oxygen and caffeine therapy to reduce apnea and accompanying intermittent hypoxemia, the incidence of intermittent hypoxemia events continues to increase during the first few months of life. Even with improvements in clinical care, standards for oxygen saturation targeting and modes of respiratory support have yet to be identified in this vulnerable infant cohort. In addition, we are only beginning to explore the association between the incidence and pattern of cardiorespiratory events during early postnatal life and both short- and long-term morbidity including retinopathy of prematurity, growth, sleep-disordered breathing and neurodevelopmental impairment. Part 1 of this review included a summary of lung development and diagnostic methods of cardiorespiratory monitoring. In Part 2 we focus on clinical interventions and the short- and long-term consequences of cardiorespiratory events in preterm infants.

Background: Retinopathy of prematurity [ROP] continues to be a significant clinical problem in preterm infants. There is a need for animal models to better understand the roles of hypoxia/hyperoxia in the pathogenesis and management of ROP., Objectives: To test the hypothesis that multiple daily cycles of intermittent hypoxia, followed by brief hyperoxia, would provide a clinically relevant protocol for generation of ROP in a rat pup., Methods: Rat pups were exposed for the first 14 days to one of three protocols: room air [RA], sustained cycles of hyperoxia/hypoxia [SHH] as previously employed to produce ROP in rat pups, and intermittent hypoxia/hyperoxia [IHH] in order to more closely simulate clinical conditions in preterm infants. Retinae were obtained at 18 days and imaged for both avascularization and neovascularization., Results: As expected, the SHH group demonstrated significantly increased avascularity [40.9 ± 7.9% of retina] which was minimal in both RA and IHH groups. All SHH exposed pups exhibited neovascularization which occurred in 5/7 IHH exposed retinae versus 0 in the RA group [p = 0.02]. However, mean number of clock hours of neovascularization after IHH was 1.9 ± 2.1 which did not differ from the RA group, and was less than in the SHH group [8.3 ± 1.9, p < 0.001]., Conclusion: A more clinically relevant intermittent hypoxia/hyperoxia [IHH] protocol does not produce the same degree of ROP as the traditional sustained hypoxia/hyperoxia [SHH] paradigm. Nonetheless, further refinement of our model may provide a suitable model for understanding the lesser degrees of ROP which predominate in preterm infants.

Objective: To test the hypothesis that preterm infants randomized to a low vs high O(2) saturation target range have a higher incidence of intermittent hypoxemia., Study Design: A subcohort of 115 preterm infants with high resolution pulse oximetry enrolled in the Surfactant, Positive Pressure, and Oxygenation Randomized Trial were randomized to low (85%-89%) or high (91%-95%) O(2) saturation target ranges. Oxygen saturation was monitored until 36 weeks postmenstrual age or until the infant was breathing room air without respiratory support for ≥72 hours., Results: The low target O(2) saturation group had a higher rate of intermittent hypoxemia (≤80% for ≥10 seconds and ≤3 minutes) prior to 12 days and beyond 57 days of life (P < .05). The duration shortened (P < .0001) and the severity increased (P < .0001) with increasing postnatal age with no differences between target saturation groups. The higher rate of intermittent hypoxemia events in the low target group was associated with a time interval between events of <1 minute., Conclusion: A low O(2) saturation target was associated with an increased rate of intermittent hypoxemia events that was dependent on postnatal age. The duration and severity of events was comparable between target groups. Further investigation is needed to assess the role of intermittent hypoxemia and their timing on neonatal morbidity., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Objective: Retinopathy of prematurity (ROP), a vasoproliferative disorder of the retina in preterm infants, is associated with multiple factors, including oxygenation level. We explored whether the common intermittent hypoxemic events in preterm infants are associated with the development of ROP., Study Design: Oxygen desaturation events were quantified in 79 preterm infants (gestational age, 24 to 27-6/7 weeks) during the first 8 weeks of life. Infants were classified as requiring laser treatment for ROP versus having less severe or no ROP. A linear mixed model was used to study the association between the incidence of intermittent hypoxia and laser treatment of ROP, controlling for gestational age, sex, race, multiple births, and initial severity of illness., Results: For all infants, hypoxemic events increased with postnatal age (P<.001). Controlling for all covariates, a higher incidence of oxygen desaturation events was found in the infants undergoing laser therapy for ROP (P<.001), males (P<.02), and infants of younger gestational age (P<.003)., Conclusions: The incidence of hypoxemic events was higher in infants with ROP requiring laser therapy. Therapeutic strategies to optimize oxygenation in preterm infants should include minimization of desaturation episodes, which may in turn decrease serious morbidity in this high-risk population., (Copyright (c) 2010. Published by Mosby, Inc.)