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A review of oxygen resuscitation in preterm infants at birth reveals that high oxygen concentrations may not be as toxic as previously thought, but also failed to identify an ideal FiO2.
Updated guidance is on the way for supplemental oxygen in preterm infants, but an ideal recommendation for the amount of oxygen to be used remains elusive.
Whereas many preterm infants require supplemental oxygen at birth, past studies have suggested that high levels of initial fraction of inspired oxygen (FiO2) are particularly toxic to preterm infants, yet there has been-and remains-no clear evidence on the optimal FiO2 levels for resuscitation in these preemies.
A new study, initiated by the International Liaison Committee on Resuscitation (ILCOR) Neonatal Life Support Task Force and published in Pediatrics, reviewed current literature and guidance on morbidity and mortality effects of high versus low Fio2 for resuscitation in infants born at 35 weeks of gestation or less. Whereas the study did not identify an ideal initial FiO2 for preterm infant resuscitation, it did seem to contradict prior notions that high FiO2 could be toxic to newborns.1 Results of the study, which reviewed 10 randomized control studies and 4 cohort studies involving more than 5600 patients, showed no statistical significance in short-term or long-term mortality or long-term neurodevelopment impairment when starting with low versus high FiO2 support at birth.
Michelle Welsford, BSc, MD, FACEP, CCPE, FRCPC, professor and interim director of emergency medicine at McMaster University, Hamilton, Ontario, Canada, medical director of the Hamilton Health Sciences Centre for Paramedic Education and Research, staff emergency physician at Hamilton Health Services, and lead author of the study, says the study confirms that although term infants can often tolerate respiratory support with room air at birth, the majority of newborns born at 32 weeks’ gestation or less will require additional oxygen supplementation within 5 minutes of birth, starting with a low oxygen level and titrating up to targeted saturation that will support life-sustaining oxygenation while preventing injury from hyperoxia. As to the lack of more specific guidance on ideal FiO2 levels, Welsford says more research is needed.
“There is still a knowledge gap regarding the specific ideal FiO2 for initial management in preterm infants. However, given most preterm neonates ≤32 weeks’ gestation will require some oxygen supplementation, the key questions to focus on may be less about the specific starting FiO2 (0.21-0.30), and more related to the process to titrate the oxygen and the best target saturations,” she says.
Final guidelines are coming
The study was conducted in order to update the ILCOR guidelines from 2015, and Welsford says new recommendations have now been created and posted for public comment, with a finalized recommendation due later this year.
As Welsford suggests, the proposed new guidelines recommend beginning oxygen resuscitation in preterm infants at 21% to 30%, increasing to 60% up to 100% as needed to reach the desired oxygen concentration using pulse oximetry.
“Concern remains that the oxygen concentrations to which preterm infants are first exposed if they need resuscitation immediately after birth may be a critical contributor to outcomes regardless of subsequent oxygen exposure,” according to the proposed guidelines. “It is unclear whether low or high oxygen concentrations may have undesirable effects. In still suggesting to start with low oxygen concentrations, we place value on avoiding exposure of preterm babies to additional oxygen without proven benefit for critical or important outcomes, as we are cognizant of harms in preterm animals and increased neonatal mortality in term infants exposed to high initial FiO2 concentration.”
1. Welsford M, Nishiyama C, Shortt C, et al; International Liaison Committee on Resuscitation Neonatal Life Support Task Force. Initial oxygen use for preterm newborn resuscitation: a systematic review with meta-analysis. Pediatrics. 2019;143(1):e20181828. Available at: http://pediatrics.aappublications.org/content/143/1/e20181828.long?sso=1&sso_redirect_count=1&nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token. Accessed February 2, 2019.