CARDIAC AND RESPIRATORY ACTIVITY IN RELATION TO GESTATION AND SLEEP STATES IN NEWBORN-INFANTS

In order to provide normative values of heart and respiratory rate and variability in relation to gestation and sleep states, 32 neonates who were free from cardiopulmonary disease were studied during the lst-6 day of life. The infants were grouped as follows: group A, 9 infants with gestational ages of 27-33 wk; group B, 14 infants with gestational ages of 34-36 wk; and group C, 9 infants with gestational ages of 37-40 wk. Recordings and observations were made during a 1-hr postprandial nap. During active sleep (AS) and quiet sleep (QS), heart rate, short-term and long-term variability of the heart rate, respiratory rate, variability of the respiratory rate and apnea density were measured. Both the long- and short-term heart rate variability was less in preterm infants (group A) than the less immature or full term infants (groups B and C, P < 0.01). Breath-to-breath respiratory variability was not significantly affected by gestational age, whereas percent duration of apnea was less in full term (group C) than the preterm groups of infants during quiet sleep (groups A and B, P < 0.05). There was no significant difference between baseline heart rate, short-term heart rate variability, and respiratory rate during AS and QS states at any given gestational age. Long-term variations in heart rate, breath-to-breath respiratory variability, and percent duration of apnea were significantly less in QS in comparison to AS at each gestational age group (P < 0.01). Speculation: Systematic monitoring of newborn infants by the techniques presented in this report would further define normal cardiorespiratory functions in relation to maturity and sleep states. Application of these techniques to the study of the distressed newborn should provide an early indication of morbidity and recovery from disease. © 1979 International Pediatric Research Foundation, Inc.