Impact of blood sampling in very preterm infants

In a prospective investigation, 99 very preterm infants (gestational age (G A) 24 - 32 weeks, birthweight 560 - 2255 g) were studied during the first 4 weeks of life. The infants were divided into two groups: infants born extr emely early (GA < 28 weeks, n = 20) and infants of GA 28 - 32 weeks; the gr oups were then subdivided into critically ill or not. Diagnostic blood samp ling and blood transfusion events were recorded. In total, 1905 blood sampl es (5253 analysis) were performed, corresponding to 0.7 samples (1.9 analys is) per day per infant. The highest frequencies were found during the first week, in infants with extremely low GA and in critically ill infants. The mean blood loss and transfusion volume values were 13.6 ml/kg and 6.3 ml/kg , respectively. In total, 19 infants (19%) received 34 transfusions corresp onding to 0.3 transfusions per infant. Thirteen out of 20 infants of extrem ely low GA received 28 blood transfusions, corresponding to 27.0 ml/kg of b lood on average during the study period. Four developed late anaemia; thus, in total, 14 (70%) of the infants born extremely early received 35 transfu sions during the first 3 months of life, corresponding to a total mean of 3 4.8 ml/kg. For the extremely preterm infants a significant correlation betw een sampled and transfused blood volume was found (mean 37.1 and 33.3 ml/kg , respectively, r = + 0.71, p = 0.0003). The most frequently requested anal yses were glucose, sodium and potassium. Few blood gas analyses were reques ted (1.9/infant). No blood losses attributable to excessive generous sampli ng were detected. The results show an acceptable low frequency of sampling and transfusion events for infants of GA 28 - 32 weeks. The study emphasize s the necessity of thorough reflection and monitoring of blood losses when ordering blood sampling in extremely preterm, critically ill infants.