Blood transfusion in anemic infants with apnea of prematurity

We found recently that blood transfusions had no effect on bradycardia and hypoxemia, the clinically important components of apnea of prematurity, in mildly anemic infants. Here, we wanted to know whether this also holds true for more severely anemic patients. Nineteen preterm infants, median gestational age at birth 25 (range 22-30) weeks, age at the time of study 5.5 (range 1-13) weeks, for whom a blood transfusion was ordered because of recurrent episodes of bradycardia and/or hypoxemia in conjunction with anemia (median hemoglobin level 78 g/l, range 63-98 g/l) were investigated. One infant received two transfusions and was thus studied twice. 4-hour recordings of pulse oximeter saturation (SpO(2)), pulse waveforms, electrocardiogram, breathing movements, and nasal airflow were performed immediately before transfusion of 20 ml/kg packed red blood cells and again 24 h later. The recordings were analyzed for baseline heart and respiratory rates and SpO(2), all measured during regular breathing, as well as for apnea (>/=20 s), bradycardia (heart rate <2/3 of baseline for >/=4 s), and episodic desaturation (SpO(2) /=4 s). There was no significant change in the combined frequency of bradycardia and desaturation, the primary study end point - median 6.4/h (range 3.0-13.5/h) before versus 4.6/h (range 0.6-15.7/h) after transfusion -, although there was slightly less bradycardia - 0.8/h (range 0.0-8.8/h) versus 0.7/h (range 0.0-5.1/h; p < 0.05). Baseline heart and respiratory rates decreased, respectively, from 163/min (range 140-182/min) and 58/min (range 34-98/min) to 152/min (range 134-172/min) and 55/min (range 36-82/min; p < 0.01). We conclude that blood transfusions significantly reduced heart and respiratory rates in these anemic infants, but had little effect on apnea of prematurity.