Effects of anaemia on haemodynamic and clinical parameters in apparently stable preterm infants

The criteria for erythrocyte transfusion in stable premature infants are currently controversial. Haemodynamic measurements are not common in transfusion practice. The purpose of this study was to determine whether haemodynamic measurements could be helpful as objective criterion for transfusion decisions. We, therefore, evaluated clinical and haemodynamic changes in stable, anaemic, premature infants before and after transfusion using our current blood transfusion protocol based on a haematocrit threshold (<24%) and the neonatologist's discretion.

Stable premature infants with a haematocrit level ≤30% were prospectively enrolled into the study. Cerebral, intestinal and renal blood flow velocities, cardiac function parameters and vital signs were measured up to three times following every routine haematocrit analysis. Moreover, transfused infants were evaluated three more times: directly before transfusion, and 24 hours and 72 hours after transfusion.

Thirty-six infants were enrolled and 23 of them were transfused. Subgroup analysis of transfused infants showed a significant decrease in cerebral blood flow velocities, cardiac output and heart rate. These changes persisted after transfusion. In the entire cohort, the degree of anaemia correlated with the increase of cerebral blood flow velocities, heart rate and cardiac output.

Cerebral blood velocities in the anterior cerebral artery might represent an objective Doppler sonographic criterion indicating the need for transfusion. The measurement of these velocities is non-invasive and quick and easy to perform. However, a randomised, controlled trial is necessary before a formal recommendation can be made.