Bromide Space Studies in Infants of Low Birth Weight

Abstract

The present study reports measurements of the corrected bromide space (CBS) in 74 neonates delivered vaginally and studied within 24 h of birth. The results in 37 normally grown (NG) infants ranging in birth weight from 960 to 3,540 g with gestational intervals of 27-43 weeks are contrasted with findings in 37 intrauterine growth-retarded infants (IGR) ranging from 1,000 to 2,460 g in birth weight with gestational intervals of 35-44 weeks.Although a direct relation exists between CBS (liters) and a variety of variables of fetal maturity in both NG and IGR infants, the CBS in both groups would appear best related to birth weight. The corrected bromide space of the IGR was virtually identical with that of their weight peers, there being no significant difference in the regression for CBS versus birth weight in the two groups. Log-log plot of this relation yields a correlation coefficient (r) of 0.98, and may be expressed as:log CBS (liters) = 0.92 X log wt (kg) -0.371 Closer inspection of this relation revealed that an unequal distribution, with preponderance of values below the regression line at higher birth weights, was apparent. This 'tail off' suggested a curvilinear relation of CBS with increasing birth weight, and was even more apparent when the CBS data were expressed as percentage of bcdy weight (ml/kg). The mean CBS/kg in NG prematures (424±SE 7.5 ml/kg) was clearly higher (P<0.001) than in mature study infants (376±SE 8.4 ml/kg). Likewise, the average CBS/kg in the mature IGR (419±SE 11.3 ml/kg) was significantly higher (P<0.025) than the mean for the NG infants (376±SE 8.4 ml/kg). Comparison of data from NG and IGR infants revealed that 3 of 10 premature infants and 10 of 27 mature IGR infants have a CBS/kg more than 2 SD above the mean in NG infants; a CBS in excess of 476 ml/kg was observed in 11 study infants, all but 1 of whom were IGR. Speculation

Antipyrine Space Studies and Cell Water Estimates in Infants of Low Birth Weight

“…Both groups of infants demonstrate changes in body composition reflecting either interrupted or disturbed developmental sequences when compared with mature, normally grown (NG) neonates. Previous studies from this laboratory have recorded the similarity of alterations in 10-min albumin space ("plasma volume") [8] and 3-hr bromide space ("extracellular volume") [9] in fetal growth-retarded neonates to those changes observed in postnatal protein-calorie malnutrition [10,19,20]. The present report presents observations concerning concurrent measurements of antipyrine and bromide spaces in 67 neonates delivered vaginally and studied within 24 hr of birth.…”

“…Because of our inability to express in vivo data on a "fat-free lean mass" basis and in order to minimize the effects of altered body fat on these results, ICW/APS ratios were calculated as additional estimates of cell water. Environmental conditions during these studies and methods used in classification of infants as normally grown, moderately growth-retarded or severely growthretarded have previously been described in detail [8][9][10]. As in previous studies, the cord was generally clamped after the first breath; therefore, study infants received a placental transfusion.…”

“…Umbilical venous catheterization and injection of a sterile solution containing 2% NaBr and 0.5% antipyrine (l-phenyl-2,3-dimethylpyrazolone-5-one) were done in all study infants [9,46]. Quantity of bromide injected averaged 65 mg/kg (range, 37-93 mg/kg); concentrations of plasma bromide ranged from 9 to 21 mg/100 ml (mean, 14.3 mg/100 ml).…”

“…The corrected bromide space (CBS) was estimated in precisely the same manner as previously described [9]. Levels of plasma antipyrine were estimated in duplicate on 1-, 3-, and 5-hr postinjection samples using the micromethod of Mendelsohn and Levin [3,32]; average coefficient of variation was 2.2%.…”

Direct assessment of extracellular water volume by the bromide‐dilution method in growth hormone‐deficient adults*

“…Loss of bromide in the urine was assumed to be negligible on the basis of stable plasma bromide concentrations in the samples obtained at 90, 120 and 150min. Plasma bromide was measured colorirnetrically at 440 nm by the gold bromide technique [25]. Plasma bromide levels ranged between 2 and 3mmolL-', which is well below the therapeutic or toxic levels.…”