Neonatal resuscitation adhering to oxygen saturation guidelines in asphyxiated lambs with meconium aspiration

Abstract

BACKGROUND The Neonatal Resuscitation Program (NRP) recommends upper and lower limits of preductal saturations (SpO2) extrapolated from studies in infants resuscitated in room air. These limits have not been validated in asphyxia and lung disease. METHODS Seven control term lambs delivered by cesarean section were ventilated with 21% O2. Thirty lambs with asphyxia with meconium aspiration were randomly assigned to resuscitation with 21% O2 (n = 6), 100% O2 (n = 6), or initiation with 21% O2 followed by variable FIO2 to maintain NRP target SpO2 ranges (n = 18). Hemodynamic and ventilation parameters were recorded for 15 min. RESULTS Control lambs maintained preductal SpO2 near the lower limit of NRP target range. Asphyxiated lambs had low SpO2 (38 ± 2%), low arterial pH (6.99 ± 0.01), and high PaCO2 (96 ± 7 mm Hg) at birth. Resuscitation with 21% O2 resulted in SpO2 values below the target range with low pulmonary blood flow (Qp) compared to variable FIO2 group. The increase in PaO2 and Qp with variable FIO2 resuscitation was similar to control lambs. CONCLUSION Maintaining SpO2 as recommended by NRP by actively adjusting inspired O2 leads to effective oxygenation and higher Qp in asphyxiated lambs with lung disease. Our findings support the current NRP SpO2 guidelines for O2 supplementation during resuscitation of an asphyxiated neonate.

Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model

“…The decrease in PVR, in this case, can be directly related to the PaO 2 achieved by various oxygen concentration during resuscitation. We have previously shown in an asphyxiated model with lung disease, use of 21% O 2 may not be adequate to achieve pulmonary vasodilation secondary to low PaO 2 levels ( 16 ), although in a term model without lung disease use of 21% O 2 did result in significant decrease in PVR ( 16 , 19 ).…”

“…In our study, titrating oxygen to maintain SpO 2 in target range resulted in an average PaO 2 of 54 mmHg while the continuous use of 21% resulted in an average PaO 2 of 35 mmHg during the first 30 minutes after birth. A PaO 2 of at least 45 mmHg is required for successful pulmonary vascular transition ( 16 , 19 , 33 , 36 ). To achieve a delicate balance between hyperoxia and hypoxia, maintaining SpO 2 in the target range suggested by NRP may be safe until more evidence is available in preterm infants.…”

“…In the targeted oxygen group (group 3), the O 2 was initiated at 21% and titrated to maintain oxygen in the NRP specified range as mentioned above. If preductal SpO 2 was outside this range, inspired oxygen was adjusted by 5% every 15 s. Term healthy lambs were ventilated with 21% irrespective of SpO 2 and served as controls ( 16 ). After the first 30 min, the variable O 2 group was further subdivided into three saturation target ranges to mimic NeOPrOM studies (85–89%, 90–94% and 95–99% - data not shown in this manuscript) ( 17 ).…”

Bidirectional Ductal Shunting and Preductal to Postductal Oxygenation Gradient in Persistent Pulmonary Hypertension of the Newborn

“…The study protocol was approved by the Institutional Animal Care and Use Committee (IACUC, protocol #20267) at the University of California Davis (UCD) and has been described in detail previously [ 8 , 9 , 10 ]. This institution is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care, International (AAALAC).…”

How Do We Monitor Oxygenation during the Management of PPHN? Alveolar, Arterial, Mixed Venous Oxygen Tension or Peripheral Saturation?

“…In our lab, in a meconium aspiration model and a preterm RDS model, a PVO 2 demonstrated a change point of 25 and 32 mmHg respectively [ 40 , 41 ] ( Figure 4 ). The utility of PVO 2 from the UVC during the management of PPHN requires further exploration.…”