Fellow University at Buffalo Buffalo, New York, United States
Background: Current resuscitation guidelines for resuscitating preterm infants recommend beginning with 21-30% oxygen. A recent meta-analysis showed that preterm neonates, who do not achieve a heart rate (HR) of ≥100 bpm & peripheral oxygen saturation (SpO2) of ≥ 80% by 5 min, are at an increased risk of mortality and morbidity.
Objective: To evaluate if initiation of resuscitation with 30% O2 followed by titration based on SpO2 in preterm surfactant deficient lambs with mild (HR 60-90 bpm) and severe (HR<60 bpm) bradycardia, can achieve the primary outcome of HR≥100 bpm & SpO2 ≥ 80% by 5 min.
Design/Methods: Cord in preterm lambs (126-128d) was occluded to achieve mild or severe bradycardia. A) Mild bradycardia requiring ventilation (PPV) alone: the cord was occluded until a HR of 60-90 bpm and ventilated with an initial O2 of 30% & the O2 titrated every min until the primary outcome was achieved. B) Severe bradycardia requiring PPV and chest compressions(CC): the cord was occluded until HR was <60 bpm and ventilated with an initial O2 of 30%. After 30s of PPV, CC was performed along with PPV in the ratio of 3:1 with 100% O2, until a HR of >60 bpm. PPV with 100% O2 was continued until the primary outcome was achieved. The time taken to achieve the primary outcome, gas exchange, and hemodynamics were recorded.
Results: Characteristics of the lambs are shown in table 1. No lambs achieved the primary outcome by 5 min. Time taken to achieve primary outcome was significantly shorter in preterm lambs with HR <90 bpm compared to those resuscitated with a HR <60 bpm (fig 1). Supplemental O2 use to achieve a HR of ≥ 100 bpm was 83±18 % when initial HR was <90 bpm & 100±0 % with initial HR <60 bpm. To achieve a HR of 100 bpm & SpO2 of 80%, 100% O2 was required in both groups. The arterial oxygenation (PaO2) and peak pulmonary flow (PBF) were significantly higher than the baseline values at the primary composite outcome (fig 2). The peak PBF was 2-fold significantly higher compared to baseline when assessed at the primary composite outcome. The peak carotid flow (CBF) did not increase significantly (fig 3). Conclusion(s): In asphyxiated preterm lambs, 100% O2 was needed to achieve a HR of ≥ 100 bpm & SpO2 ≥ 80% regardless of the extent of resuscitation. Despite ventilation with 100% O2 , the pulmonary vascular transition was suboptimal in a surfactant deficient preterm newborn transition. Our findings suggest that a depressed preterm neonate be resuscitated with 100% initial O2. Clinical studies are needed to validate our findings.
Figure shows Baseline Characteristics of the preterm lambs
Figure shows the time taken to achieve target of HR≥100 and SpO2 ≥ 80%
Peak pulmonary blood flow during preterm resuscitation
Peak carotid blood flow during preterm resuscitation
Authors/Institutions: Mausma Iqbal Bawa, University at Buffalo, Buffalo, New York, United States; Sylvia F. Gugino, University at Buffalo, Buffalo, New York, United States; Justin Helman, University at Buffalo, Buffalo, New York, United States; Nicole k. Bradley, University at Buffalo, Buffalo, New York, United States; Lori Nielsen, University at Buffalo, Buffalo, New York, United States; Carmon Koenigsknecht, University at Buffalo, Buffalo, New York, United States; Munmun Rawat, University at Buffalo, Buffalo, New York, United States; Jayasree Nair, University at Buffalo, Buffalo, New York, United States; Andreina Mari, University at Buffalo, Buffalo, New York, United States; Srinivasan Mani, University at Buffalo, Buffalo, New York, United States; Satyan Lakshminrusimha, UC Davis, Sacramento, California, United States; Praveen Chandrasekharan, University at Buffalo, Buffalo, New York, United States
