481 - Initial use of 100% but not 60% or 30% oxygen achieved a target heart rate of 100 and preductal saturations of 80% faster in a bradycardic preterm model

Poster Number: 481
Publication Number: 481.231

Mausma Bawa, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Sylvia Gugino, SUNY at Buffalo, Buffalo, NY, United States; Justin Helman, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Bufalo, NY, United States; Nicole Bradley, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Lori Nielsen, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, buffalo, NY, United States; Srinivasan Mani, ProMedica Toledo Children's Hospital, Perrysburg, OH, United States; Andreina Mari, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Depew, NY, United States; Arun Prasath, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Williamsville, NY, United States; Clariss Blanco, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Aditya Gupta, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; JESSICA G. FLORES, New York state environmental Health Center, Buffalo, NY, United States; Pedro Rivera-Hernandez, University at Buffalo, Buffalo, NY, United States; Jayasree Nair, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Munmun Rawat, University at Buffalo, Buffalo, NY, United States; Satyan Lakshminrusimha, University of California Davis Children's Hospital, Sacramento, CA, United States; Praveen Chandrasekharan, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States

Background: In bradycardic preterm neonates who do not require chest compressions(CC), failure to achieve a heart rate (HR) of ≥100 bpm & peripheral oxygen saturation (SpO2) of ≥ 80% by 5 min increased the risk of mortality 18 times. It remains unknown if initiating resuscitation with 30% oxygen (O2) in an asphyxiated preterm neonate with surfactant deficiency, based on current recommendations, is sufficient to achieve this target by 5 min.

Objective: To evaluate the effect of initiating PPV with 30% O2 (OX30), 60% O2 (OX60) & 100% O2 (OX100) on a) primary outcome - achieve a combined HR of ≥100 bpm & peripheral SpO2 of ≥ 80% by 5 min b) secondary outcomes - Time to achieve primary outcome, effect on gas exchange, pulmonary/systemic hemodynamics, oxygen delivery to brain & oxidative injury.

Design/Methods: Preterm lambs (126-128d, ≡ < 28-week human neonate) were asphyxiated to achieve HR < 100bpm after instrumentation. Positive pressure ventilation (PPV) was initiated with OX100, OX60, and OX30 for 2 min and titrated based on recommended preductal SpO2. The titration of O2 was proportional to the difference between observed SpO2 and target SpO2 and was performed every min. Data on gas exchange and hemodynamics was collected for the first ten min.

Results: Characteristics of the lambs are shown in fig 1a. Four in OX100 & two in OX60 achieved primary outcome by 5 min, while none achieved in OX30. Time taken to achieve the primary outcome in OX100 (6±2 min) was significantly lower (p-0.042), compared to OX30 (10±3 min). With OX60 it took 8±3 min to achieve the target. The preductal SpO2 was significantly higher with OX100 compared to OX30 (fig 1). Oxygen concentration used during the first 10 min of PPV with OX100 was significantly lower than OX30 and higher than OX60 (fig 1). The arterial oxygenation (PaO2) and the peak pulmonary blood flow (PBF) were lowest in the OX30 group (fig 1 & 2). There was no difference in the left carotid blood flow between the groups (fig 2B). O2 delivery to the brain (fig 3A) and the oxidized to reduced glutathione ratio (fig 3B) was not different between the groups.Conclusion(s): In asphyxiated preterm lambs, an initial O2 of 100%, decreased the duration to achieve HR of ≥ 100 bpm & SpO2 ≥ 80% compared to 60% & 30%. The arterial oxygenation and peak pulmonary blood flow were lowest with OX30. There was no difference in oxidative stress between the groups. Although 100% O2 reduced the time to achieve the primary outcome, more translational studies are required to understand the pulmonary and cerebral oxidative stress secondary to higher oxygen exposure in the background of asphyxia.
Mausma Bawa, MDCV PAS 2022.pdf