A comparison of respiratory function in Afro-Caribbean and Caucasian infants.

Race is recognized as an important determinant of lung function in children and adults, but limited data exist for infants. Accurate interpretation of lung function tests during the neonatal period may depend on appropriate values for predicting normality. The aim of this study was to compare tidal breathing parameters, Hering-Breuer reflex (HBR) activity, and total respiratory compliance (Crs) in healthy newborn caucasian (white) and Afro-Caribbean (black) infants, to determine whether separate reference values were required for these two ethnic groups. Respiratory function was measured in 33 healthy black infants, 18 of whom were premature, and 33 healthy white infants matched for sex, gestational age, weight, postnatal age, and maternal smoking during pregnancy. There were no significant paired differences between black and white infants with respect to minute ventilation, respiratory frequency, the ratio of time to reach peak expiratory flow to total expiratory time, or HBR activity. Values of Crs were similar in black and white full-term infants (37.5 (SD 9.0) versus 35.0 (6.3) ml.kPa-1, respectively) suggesting that, in the immediate newborn period, separate reference values are not necessary for these parameters. However, Crs was somewhat lower in black than white preterm infants (26.0(5.2) versus 29.5(7.2) ml.kPa-1, this difference reaching statistical significance if results were expressed in relation to body weight (95% confidence interval of within-pair differences -4.0 to -0.02 ml.kPa-1 x kg-1; p < 0.05). We conclude that no separate reference values for tidal breathing, Hering-Breuer reflex activity or total respiratory compliance are required for white and black babies in the immediate newborn period.(ABSTRACT TRUNCATED AT 250 WORDS)