The value of capillary whole blood lactate for blood transfusion requirements in anaemia of prematurity

Objective: To evaluate the usefulness of blood lactate as an indication for blood transfusion in anaemia of prematurity by means of a study protocol w hich considers the site of blood sampling and the repeatability of lactate measurements. Design: Prospective clinical study. Setting: Multidisciplinary, neonatal-paediatric intensive care unit of a no n-university, teaching children's hospital. Patients and methods: Comparison of pre- and 48-h post-transfusion capillar y whole blood lactate in 18 anaemic premature babies. In 30 neonates the ag reement between capillary and arterial lactate was analysed by using the Bl and Altman plot. In 30 stable premature infants four capillary lactate meas urements were carried out within 24 h and analysed with regard to variabili ty (coefficient of variation (CV); association between SD and mean) and to establish normal values. Results: In the transfused infants, haematocrit increased from 23 (SD 3)% t o 37 (SD 3)%. Mean lactate decreased from 2.5 (SD 1.0) to 1.7 (SD 0.5) mmol /l (p = 0.003). Pre-transfusion lactate did not correlate with pre-transfus ion haematocrit, heart rate, respiratory rate, number of apnoeas/bradycardi as and weight gain (multiple regression). The mean difference between capil lary and arterial lactate was 0.17 (SD 0.24) mmol/l and the 95% confidence interval (CI) was -0.31 to 0.65 mmol/l. The CV of repetitive measurements w as 19.8 (SD 9.8)% and SD correlated positively with mean lactate values (p = 0.001); the 95% CI (normal range for premature infants) was 1.56-1.90 mmo l/l. Conclusions: Capillary whole blood lactate measurements in newborn babies a gree excellently with arterial values. Lactate measurements add little info rmation to the decision whether to transfuse or not, considering the variab ility of this parameter in stable premature infants and the lack of correla tion with other possible clinical indicators of compromised oxygen delivery .