Myocardial Adaptation to Anemia and Red Blood Cell Transfusion in Premature Infants Requiring Ventilation Support in the 1st Postnatal Week

Background: Although transfusion practice in very premature infants is becoming more restrictive, little is known about myocardial adaptation to anemia during the 1st postnatal week. Objectives: To determine the central hemodynamic effects of anemia and red blood cell transfusion in very preterm infants undergoing intensive care. Methods: Twenty-nine neonates of less than 30 weeks gestational age were treated for respiratory distress syndrome, following a strict protocol. Echocardiographies were performed at the 4th and 6th postnatal days, which corresponded to, respectively, just before and 48 h after an erythrocyte transfusion of 15 ml/kg in the 12 anemic infants. Results: Anemic infants had increased stroke volume [2.1 (1.8–2.3) vs. 1.5 (1.3–1.6) ml/kg] and left ventricular (LV) output [312 (271–345) vs. 206 (177–240) ml/min/kg]. The relationship of the heart rate-corrected velocity of circumferential fiber shortening to LV end-systolic meridional wall stress indicated a higher contractile state in the anemic infants, with a higher y-intercept (p = 0.03) and a steeper slope (p = 0.05) of the regression line than in the nonanemic patients. Posttransfusion, the stroke volume, LV output, shortening fraction, and contractile state decreased to the values observed in the nonanemic infants. Conclusions: Myocardial contractility was a major component of the circulatory adjustments in the anemic premature infants requiring ventilation support in the early neonatal period. Changes in LV performance associated with anemia were reversed by transfusion with no detrimental effect on right ventricular function, LV preload or the respiratory status of these patients.