Pulmonary excretion of carbon monoxide in the human infant as an index of bilirubin production. IV. Effects of breast-feeding and caloric intake in the first postnatal week.

Measurements of the pulmonary excretion rate of carbon monoxide (VEco) as an index of bilirubin production in the first several days of life were taken from 64 breast-fed or bottle-fed infants. Twenty-one infants (greater than or equal to 37 weeks of gestation) were breast-fed; 43 infants (28 to 42 weeks of gestation) were bottle-fed a commercially prepared formula. Information pertaining to their caloric intake during the 24-hour period preceding VEco determination was taken from 38 of the 43 infants who were bottle-fed and they were placed into three groups based on their caloric intake: (1) less than or equal to 60 kcal/kg/day (19 infants); (2) 61 to 100 kcal/kg/day (7 infants); and (3) greater than 100 kcal/kg/day (12 infants). There was no significant difference in bilirubin production between bottle-fed and breast-fed infants. No effect of caloric deprivation on bilirubin production was demonstrated. The mean VEco values were 18.5 +/- 0.9 (SE) for group 1, 17.7 +/- 1.8 (SE) for group 2, and 16.2 +/- 1.1 (SE) microliter/kg/hr for group 3.

Pulmonary excretion of carbon monoxide in the human newborn infant as an index of bilirubin production: III. Measurement of pulmonary excretion of carbon monoxide after the first postnatal week in premature infants.

Using a single pass, flow-through system, the excretion rate of endogenously produced carbon monoxide (VeCO) was measured as an index of bilirubin production in 41 Caucasian infants of various gestational ages after the first postnatal week. twenty-one were less than or equal to 32 weeks gestation. The mean slope for the 25 premature infants with multiple VeCO determinations was -0.21 +/- 0.11 (SE) microliters/kg/hour per day (P less than .025, one-tailed). Fifteen premature infants with at least three VeCO determinations during the first 30 days of life had an average decrease in total CO excreted of 1.33% per day compared to the extrapolated initial value of total CO excretion of 27.0 +/- 2.0 (SE) microliters/hour, giving a calculated maximum red cell life span of 75 days.

Pulmonary excretion of carbon monoxide in the human infant as an index of bilirubin production. I. Effects of gestational and postnatal age and some common neonatal abnormalities.

Using a single pass, flow-through system, the pulmonary excretion rate of endogenously produced carbon monoxide was measured as an index of bilirubin production in human infants with varying gestational and postnatal ages and with a variety of clinical abnormalities. No significant difference in VECO was found related to sex or gestational age. The mean VECO for a small group of Oriental infants was significantly increased. VECO decreased with increasing postnatal age. As expected, infants with hemolytic disease of the newborn had a markedly increased mean VECO. Infants with jaundice of unknown etiology also had an elevated mean VECO, implying that increased bilirubin production may be a factor contributing to the "nonphysiologic" bilirubinemias of these infants.

Neonatal hypoxia and pulmonary vasospasm: response to tolazoline.

Forty-six neonates with hypoxemia were treated with tolazoline, a pulmonary vasodilator, within the first two days of life. Eight of ten (80%) infants without apparent lung disease responded with a mean increase in PaO2 of 116 torr within one hour of beginning tolazoline infusions. One of the responding infants and two nonresponders died. Thirty-six additional infants with a variety of pulmonary disorders had severe hypoxemia which was refractory to mechanical ventilation. Twenty-one (58%) responded with a mean increase in PaO2 of 130 torr within one hour after beginning tolazoline and 13 (62%) of these survived. Fifteen patients had little or no improvement in PaO2 following tolazoline and only three (20%) of these infants survived. Responders could not be distinguished from nonresponders by clinical or laboratory features prior to therapy with tolazoline. Fourteen infants experienced complications possibly related to tolazoline.

Determing the pulmonary excretion rate of carbon monoxide in newborn infants.

A simplified technique was devised for measurement carbon monoxide excretion rates in newborn infants. Determinations can be performed quickly and repetitively in a noninvasive manner, with a sensitivity sufficient for use even on small preterm infants. Resolution of the method is +/- 4.3 mul/h (SD); however, variations in infant respiration rate may cause much greater changes in actual excretion rate. Preliminary results with five full-term newborn agree to within 15% of previously reported data. The system will be used extensively in ongoing studies involving total bilirubin production as a function of gestational age.