PERIPHERAL OXYGENATION AND ANEMIA IN PRETERM BABIES

A measurement of tissue oxygenation may be a better marker of transfus ion need than the Hb concentration. Peripheral fractional oxygen extra ction, oxygen consumption, and oxygen delivery were measured noninvasi vely using near infrared spectroscopy in babies, some of whom were giv en blood transfusions. The above indicators of oxygenation were measur ed in 96 preterm babies. The decision to transfuse was based on a stan dard protocol. Transfusions were not considered necessary for babies i n group 1 but were given to those in groups 2 (asymptomatic) and 3 (sy mptoms attributed to anemia). Ho and Hb fraction F (HbF) were measured in each baby. Oxygenation, Hb, and HbF measurements were made again 1 2-24 h after transfusion, and red cell volume (RCV) was calculated. Fr actional oxygen extraction was significantly higher in symptomatic (0. 43 +/- 0.06) but not asymptomatic (0.33 +/- 0.05) babies compared with control subjects (0.35 +/- 0.06). Oxygen consumption and oxygen deliv ery were similar in the three groups before transfusion. After transfu sion the mean fractional oxygen extraction fell significantly in sympt omatic but not in asymptomatic babies. There was no significant change in either oxygen consumption or oxygen delivery in symptomatic babies . The asymptomatic group had no change in oxygen extraction or oxygen consumption after transfusion, although oxygen delivery increased sign ificantly. Fractional oxygen extraction correlated with HbF (n = 66, r = 0.49, p < 0.001) and RCV (n = 19, r = -0.48, p = 0.04) and there wa s a weak correlation with Ho (n = 94, r = -0.21,p = 0.04). Peripheral fractional oxygen extraction monitored noninvasively correlated with v ariables known to determine oxygen availability to the tissues, namely RCV and HbF, and was higher in babies with symptomatic anemia and dec reased after transfusion.