A Theoretical and Practical Approach to Defining “Adequate Oxygenation” in the Preterm Newborn

Abstract

John Scott Haldane recognized that the administration of supplemental oxygen required titration in the individual. Although he made this observation in adults, it is equally applicable to the preterm newborn. But how, in practice, can the oxygen requirements in the preterm newborn be determined to avoid the consequences of too little and too much oxygen? Unfortunately, the current generation of oxygen saturation trials in preterm newborns guides saturation thresholds rather than individual oxygen requirements. For this reason, we propose an alternate model for the description of oxygen sufficiency. This model considers the adequacy of oxygen delivery relative to simultaneous consumption. We describe how measuring oxygen extraction or the venous oxygen reservoir could define a physiologically based definition of adequate oxygen. This definition would provide a clinically useful reference value while making irrelevant the absolute values of both oxygen delivery and consumption. Additional trials to test adjunctive, noninvasive measurements of oxygen status in high-risk preterm newborns are needed to minimize the effects of both insufficient and excessive oxygen exposure.

Monitoring cerebral oxygenation of the immature brain: a neuroprotective strategy?

“…In a recent comprehensive review, Andersen et al described the potential use of NIRS-derived monitoring of oxygenation adequacy as a factor in neonatal management. 54 While this review focuses on cerebral oxygenation, peripheral forms of tissue oxygenation monitoring are also mentioned as potential contributors to an assessment of a given neonate's overall physiologic oxygenation status. In addition, the introduction of a new monitoring strategy as a standard of care requires an eventual diminishing of equipoise concerning effects on outcomes, along with broad acceptance among clinicians and practitioners.…”

Management of anaemia in pre‐term infants

“…From a physiological perspective, optimal oxygen delivery to the end organs depends on three key factors: blood flow, Hb concentration and Hb‐oxygen saturation. Of these, blood flow is the most critical determinant of oxygen delivery (Andersen et al , ). The 2 hypothetical scenarios in Table highlight the limitation of Hb as a proxy for oxygen delivery (DO 2 , ml/kg/min).…”

Anemia of prematurity and cerebral near-infrared spectroscopy: should transfusion thresholds in preterm infants be revised?

“…Near-Infrared Spectroscopy (NIRS), a non-invasive measure of mixed (predominantly venous) tissue saturation, provides a tool to assess patient-specific cerebral oxygenation at the bedside and identify anemic infants whose compensatory physiologic mechanisms have been overwhelmed resulting in a drop in cerebral oxygenation below the normative range. 19 , 32 , 33 , 34 , 35 Existing data from the first two weeks of life in premature infants suggest that the normative range of cerebral regional saturations (C-rSO 2 ) is 70 ± 15%. 21 , 36 …”