Baseline respiratory sinus arrhythmia and heart rate responses during sustained visual attention in preterm infants from 3 to 6 months of age.

Three groups of preterm infants were studied longitudinally at 14, 20, and 26 weeks of age (corrected for gestational age). The groups included infants with no perinatal medical complications, those with mild respiratory problems requiring ventilatory assistance, and those with respiratory distress syndrome. Baseline heart rate and respiratory sinus arrhythmia (RSA) were recorded for 5 min, and heart rate was also recorded while the infants engaged in sustained visual attention to stimuli presented on video monitors. The heart rate response during stimulus orienting and sustained attention was smaller in those infants with respiratory distress syndrome than in the other preterm infants and in comparison with the response seen in full-term infants in previous research. Magnitude of RSA was positively correlated with the attention responses irrespective of the preterm group assignment. There was greater stability in baseline heart rate and RSA for the preterm infants than has been found with full-term infants. These data suggest that the cardiorespiratory functioning of the preterm infant indexes a stable individual difference characteristic that is correlated with heart responses during sustained attention, and heart rate attention systems may be damaged in the high-risk preterm infant.