A Further Extension of the In Vivo Oxygen-Dissociation Curve for the Blood of the Newborn Infant*

Abstract

The oxygen-dissociation curve of human fetal blood has been the subject of several previous investigations (1)(2)(3)(4)(5)(6). At saturations below 80% the curve has been described with considerable accuracy and, as in other mammalian young, is known to be displaced to the left of that for adult blood although both curves share a similar shape. Most studies have been carried out in vitro, i.e., cord blood specimens have been tonometrically equilibrated at various oxygen tensions, and the oxygen saturation has been measured.Beer, Bartels, and Raczkowski (4) and Rooth, Sj6stedt, and Caligara (5) have investigated the in vivo oxygen-dissociation curve by determining the actual oxygen and saturation at the time cord blood is sampled. Unfortunately, the curves so described do not extend into a range of oxygen content physiologic for the normal newborn infant. It is in just this range along the horizontal upper limb of the curve that precise information is necessary for calculation of venous admixture and the diffusion capacity of the lung for oxygen.One in vitro curve for fetal blood has been published, which extends well into the physiologic range (6). The present investigation represents an attempt at accurate delineation of a comparable in vivo curve. MethodsUmbilical arterial blood was obtained by catheter from 13 newborn infants. The infants comprised a crosssection of a typical newborn population (full-term and * Submitted for publication September 11, 1963; accepted November 29, 1963 (4,6). Darling, Smith, Asmussen, and Cohen (3) had found no difference between maternal and fetal blood with respect to the effect of pH change on the placement of the oxygendissociation curve, but a more recent investigation (11) indicates that there may be a significant difference in response to changes in pH.1 5 = percentage of oxygen saturation; CaO2= arterial oxygen content; PaO2 = arterial oxygen tension; Cap = oxygen capacity. 606

Acid-Base Status of ”Normal” Premature Infants in the first Week of Life

“…m easu rem ents on 0.3 ml o f blood. F o r th e c alcu latio n of th e ()2 s a tu ra tio n , th e oxygen d issociation curves o f th e fo etal blood a t v a rio u s p H in terv als w ere assum ed from p u b lish ed stu d ies [17,34].…”

Physiological significance of fetal blood gas changes elicited by different delivery postures.

“…However, hemoglobin dissociation curve at this level of Pot has a steep slope and a small change in Pot can produce a significant change in oxgen transport. Moreover, oxygen dissociation curve of fetal hemoglobin (hemoglobin F) is shifted to the left and this results in a further increase in oxygen content (Nelson et al 1964), although the increased 502 (Table 1) may be in part attributable to Bohr effect by the decreased Pco2. Consequently, even a small change in Pot of umbilical blood has also an important meaning in the clinical practice.…”

Relationship between Extracellular and Intracellular Hydrogen Ion Concentrations and Hemoglobin Oxygen Affinity in the Blood of Premature Infants with RDS

“…This conversion factor is supposed to be valid for blood of pregnant women and newborn infants too [9]. N elson et al [21] using the same factor for estimation of an in vivo oxygen dissociation curve, calculated the oxygen dissociation curve for fetal and neonatal blood at pH 7.4 to be identical with that of adult blood at pH 7.6. H ellegers and Schruefer [16] found a stronger pH effect in fetal blood.…”