Combining Restrictive Guidelines and a NIRS SCORE to Decrease RBC Transfusions

Overview

The primary aim of this study is to determine the mean number of red blood cell (RBC) transfusions received by preterm infants cared for using restrictive Hgb guidelines in combination with splanchnic to cerebral oxygenation ratio (SCOR) assessment compared to the mean number of transfusions received by preterm infants cared for using liberal guidelines alone. This study is designed as a prospective randomized controlled trial. Preterm infants less than 30 weeks gestational age and 500-1250 grams in weight will be recruited and enrolled into the study during day of life 0 to 3. Study participants will be randomly assigned into two groups: a restrictive transfusion group and a liberal transfusion group. In the liberal group, RBC transfusions will be given to subjects when their Hgb level falls below defined values that are based on respiratory support status. In the restrictive group, RBC transfusions will be given to subjects either when their Hgb level falls below defined values based on respiratory status or, despite not having reached their Hgb trigger threshold, if they manifest symptoms judged by the clinical care team to be consistent with anemia (i.e. apnea, bradycardia, or desaturation episodes) and subsequently have a near-infrared spectroscopy (NIRS) evaluation that demonstrates an SCOR \< 0.73.

Previous studies have demonstrated that premature infants transfused using restrictive guidelines, in which red blood cell (RBC) transfusions are triggered at relatively low Hgb thresholds, receive significantly fewer transfusions and have similar clinical outcomes to premature infants transfused using liberal transfusion guidelines that use higher Hgb thresholds. However, some remain apprehensive about a restrictive transfusion approach, primarily because the research remains somewhat limited. In addition, concern also exists because some previous researchers found that although there was no difference in mortality based on whether a restrictive or liberal transfusion guideline was used, they did find that a liberal transfusion policy may provide a neuro-protective benefit. This then implies that there may be circumstances in which a neonate transfused with a restrictive strategy could benefit from an increased Hgb level, but does not receive transfusion because their Hgb has not dropped below a predefined transfusion trigger level. The investigators have previously demonstrated in an observational study that measuring tissue oxygen saturation (rSO2) levels using near-infrared spectroscopy (NIRS) can be more specific in determining RBC transfusion needs in the preterm population than relying on Hgb values derived from a blood sample. Using a model to calculate the splanchnic to cerebral oxygenation ratio (SCOR) \[splanchnic rSO2 / cerebral rSO2\] could predict with a high probability if preterm infants would improve clinically after a RBC transfusion. Infants with a low SCOR, who were in a physiologic state in which blood and oxygen were being diverted away from the gastrointestinal tract, usually benefited after transfusion. Neonates with a high SCOR, in which oxygen saturation in gut tissue was relatively constant with brain tissue, were unlikely to improve with transfusion. The intent of this study is to determine whether the SCOR assessment (performed in addition to traditional measurement of Hbg) can better predict which premature infants will benefit from RBC transfusion in a subset of infants demonstrating signs of anemia before having reached the transfusion threshold of a restrictive transfusion protocol. The goal is to assess whether this additional assessment of oxygen delivery (SCOR) can safely reduce the rate of transfusion in a group of subjects treated on a restrictive protocol compared with those transfused using a liberal transfusion protocol. The hypothesis is that by incorporating a measure of transfusion need, SCOR, to the clinical management of a group of preterm infants following a restrictive guideline approach, we can still reduce the average number of transfusions that these infants receive compared to a similar group of preterm infants managed with a liberal approach, yet have no difference in morbidity, including neurological outcomes. This study is designed as a prospective randomized controlled trial. Preterm infants less than 30 weeks gestational age and 500-1250 grams in weight will be recruited and enrolled into the study during day of life 0 to 3. Study participants will be randomly assigned into two groups: a restrictive transfusion group and a liberal transfusion group. In the liberal group, RBC transfusions will be given to subjects when their Hgb level falls below defined values that are based on respiratory support status. In the restrictive group, RBC transfusions will be given to subjects either when their Hgb level falls below defined values based on respiratory status or, despite not having reached their Hgb trigger threshold, if they manifest symptoms judged by the clinical care team to be consistent with anemia (i.e. apnea, bradycardia, or desaturation episodes) and subsequently have a near-infrared spectroscopy (NIRS) evaluation that demonstrates an SCOR \< 0.73.