P0775 - Umbilical Cord Milking (UCM) During Positive Pressure Venitlation (PPV) Stablizes Hemoglobin but Increases Systemic Blood Pressure and Heart Rate In Perinatal Asphyxia

Placental transfusion by delayed cord clamping is recommended in all births except when active resuscitation is needed. In the presence of lung disease and PPV, the effectiveness of delayed cord clamping is not known. UCM accomplishes placental transfusion rapidly and can be performed simultaneously with PPV. The objective of this study was to compare UCM during PPV with immediate cord clamping (ICC) followed by PPV in the presence of birth asphyxia and lung disease in neonatal lambs. Eighteen near-term fetal lambs were instrumented to measure blood pressure, left pulmonary blood flow (Qp), carotid flow (Qca) and blood gases. Lambs were intubated and meconium mixed in amniotic fluid was instilled into the tracheal tube. Umbilical cord was compressed to induce asphyxia leading to acidosis, gasping and meconium aspiration. Lambs were randomized to PPV associated with UCM for 1min or ICC followed by PPV. Lambs were ventilated for 1h and gas exchange and hemodynamics were monitored. Birth weight (3.4 ±0.2 vs. 3.0 ±0.3 kg) and baseline hemoglobin [(Hgb) 11.8 ±0.6 vs. 12.9 ±0.5 g/dL in UCM and ICC respectively] were similar between the two groups (Table 1). Following umbilical cord compression and meconium instillation, fetal lambs were acidotic (pH 6.9±0.05, lactate 7.7 ±0.8 mM/L, base deficit -10.3 ±1.4 mEq/L) and hypoxemic (PaO2/FiO2 ratio 187±0.3 mmHg). Qca decreased and Qp increased compared to fetal baseline but were similar between the two groups (Fig 1). Systemic blood pressure and heart rate were significantly higher in the UCM group compared to the ICC group (Fig 2). The change in Hgb was significantly higher in the UCM group ( 4± 3%) relative to baseline compared to the ICC group (-4.3 ±2.5%). There was no difference in oxygen delivery to the brain between the two groups but fractional oxygen extraction was higher in the ICC group (26 ±2.6%) compared to the UCM group (17.7 ±1.6%, p=0.025). UCM during PPV is feasible in perinatal asphyxia with meconium aspiration and stablizes Hgb and reduces fractional oxygen extraction during the first 60 min after birth. However, there is an associated significant increase in heart rate and systemic blood pressure (above fetal baseline) without any change in oxygen delivery. Given the recent association of UCM with severe intraventricular hemorrhage in extremely preterm infants (Katheria et al JAMA 2019), these results are concerning and require further investigation.