PAIRED DETERMINATIONS OF BLOOD CARBOXYHEMOGLOBIN CONCENTRATION AND CARBON-MONOXIDE EXCRETION RATE IN TERM AND PRETERM INFANTS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 100  (5) , 745-755
Abstract
Paired determinations of HbCO and VeCO [CO excretion rate] were performed on 30 term infants (38-42 wk gestation) and 26 preterm infants (28-37 wk gestation) during the 1st wk of life. All subjects were breathing room air at the time of the study. Values of HbCO were corrected for RACO [room air concentration of CO] by linear regression of HbCO (% saturation) vs. RACO (ppm). Regression coefficients for term and preterm infants with no history of pulmonary impairment were nearly identical (HbCO = 0.175 RACO + 0.45, r = 0.77, n = 25 for term infants; HbCO = 0.168 RACO + 0.51, r = 0.82, n = 9 for preterm infants) and agreed well with theoretical vlaues. For the group of term infants, linear regression of VeCO (.mu.l/kg per h) vs. HbCOc, where HbCOc = HbCO -0.17 RACO, resulted in VeCO = 23.4 HbCOc + 4.02, r = 0.75, n = 30. The corresponding relationship for preterm infants with no history of pulmonary impairment was VeCO = 24.7 HbCOc + 3.85, r = 0.61, n = 13. For a subpopulation of preterm infants with a history of pulmonary dysfunction, the correlation decreased significantly, with VeCO = 4.34 HbCOc + 17.6, r = 0.097, n = 11. HbCOc is a reasonable index of VeCO and consequently of the heme catabolic rate in both term and preterm infants with no clinical history of pulmonary dysfunction, and inference of VeCO from HbCOc may be misleading in certain cases without a consideration of the factors relating these 2 variables.