A pilot randomised controlled trial of peripheral fractional oxygen extraction to guide blood transfusions in preterm infants

Abstract

Background: Peripheral fractional oxygen extraction (FOE) may be a better indicator of the need for transfusion than the haemoglobin concentration (Hb) because it is a measure of the adequacy of oxygen delivery to meet demand. A randomised controlled trial of the use of peripheral FOE to guide the need for blood transfusions in preterm infants was carried out to test this hypothesis. Method: Infants less than 1500 g birth weight who were stable and less than 2 weeks old were randomised to receive transfusions guided by either a conventional protocol based on Hb (conventional group) or a protocol based on measurements of peripheral FOE made by near infrared spectroscopy (NIRS group). Measurements of Hb and FOE were made on all infants from randomisation until discharge. The primary outcome measures were number of transfusions received, rate of weight gain, and postmenstrual age at discharge. Results: Thirty seven infants were randomised to each group. Birth weight (median, range) (1200, 1004-1373 v 1136, 1009-1285 g) and Hb (median, range) at randomisation (160, 149-179 v 155, 145-181 g/l) did not differ between the two groups. The total number of transfusions given to the NIRS group was 56 and to the conventional group 84. The median number of transfusions per infant, the median volume of blood transfused to each group, and the total number of donors to which infants were exposed were similar in the two groups. Infants transfused according to the conventional protocol were more likely to be transfused earlier and at a higher Hb than those transfused in the NIRS group. Infants in the conventional group spent a significantly shorter period than those in the NIRS group with Hb < 100 g/l. Of the 56 transfusions given to the NIRS group, 33 (59%) were given because of clinical concerns rather than because of high FOE. There was no difference in the rate of weight gain, rate of linear growth, postmenstrual age at discharge, or the incidence of chronic lung disease or retinopathy of prematurity. Conclusions: FOE measurements failed to identify many infants felt by clinicians to require blood transfusion. This may have been because clinicians relied on conventional indicators of transfusion that are vague and non-specific, or a peripheral FOE of 0.47 alone may not be a sensitive enough predictor of the need for transfusion. This requires further study.

The Relationship Between Electrocerebral Activity and Cerebral Fractional Tissue Oxygen Extraction in Preterm Infants

“…If the Hb concentration decreases, the absolute amount of oxygen transported is decreasing. Within ranges of constant oxygen demand, this may lead to a higher extraction of oxygen (18,19). These results are in line with the study of Roche-Labarbe et al (20).…”

Non‐invasive monitoring of haemoglobin concentration in paediatric surgical patients using near‐infrared spectroscopy*

“…Wardle et al conducted a trial of near-infrared spectroscopy guided blood transfusion in preterm infants. They stated that in the near-infrared spectroscopy group 59% of transfusions were given because of clinical concerns rather than because of nearinfrared spectroscopy parameters [29]. Our results support the need for caution, near-infrared spectroscopy being a promising research tool but not yet ready for routine clinical application [30].…”

Cerebral oxygenation and brain activity after perinatal asphyxia: does hypothermia change their prognostic value?

“…To investigate the balance between oxygen delivery and oxygen consumption, cFTOE can be formulated as a ratio: (SaO 2 − rScO 2 )/SaO 2 . An increase in cFTOE reflects an increase of the oxygen extraction by brain tissue, and a decrease suggests less utilization of oxygen by brain tissue in comparison with the oxygen supply (26,27).…”