Increased extracellular water volume associated with hyponatremia at birth in premature infants

Rojas, Jorge; Mohan, Petaiah; Davidson, Kathy K.

doi:10.1016/s0022-3476(84)80385-6

Cited by 23 publications

(2 citation statements)

References 13 publications

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“…Initial fluid intakes as low as 40 mL/kg/day, using 15-20% Dextrose, are often more appropriate in ventilated babies with gestational ages above 30 weeks than the more conventional 60 mL/ kgfday, assuming that humidification of the inspired gases is adequate. Plasma sodium levels less than 135 mmoVL a t birth indicate fetal overhydration secondary to maternal fluid therapy (79,101), and should be managed by appropriate reductions in fluid intake. Paradoxically change in plasma sodium during the first 48 hours was inversely related to sodium balance.…”

Section: Discussionmentioning

confidence: 99%

Mineral Balance Studies in Sick Preterm Intravenously Fed Infants during the First Week after Birth

Aiken

Sherwood²,

Kenney³

et al. 1989

Acta Paediatrica

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Mineral balance studies were performed in 61 sick preterm infants given parenteral fluids only. Their gestational ages varied from 24 to 35 weeks, and 50 required mechanical ventilation. Two consecutive balance studies were performed; the first from admission to 48 hours in all babies given maintenance fluids of 10% Dextrose, and the second from 48 hours to 7 days in those babies given intravenous feeding (IVN). At the beginning and end of each balance period, the baby was weighed and an arterial blood sample taken for blood gases, electrolyte, urea, creatinine and protein determinations. During the balance period all urine was collected and analysed for electrolyte, urea, and creatinine composition, and all fluid intake was recorded. The balance of a mineral was calculated as the difference between parenteral intake and urine output. Infants requiring IVN were allocated alternatively to regimen X or regimen Y, which had the same calcium content of 9.5 mmol/L, but different phosphate contents, regimen X containing 7.3 mmol/L and regimen Y 11.6 mmol/L. In those infants requiring prolonged IVN, 12–24 hour balance studies were performed at weekly intervals after day 10. 1. Phosphate deficiency developed in infants given regimen X, who had higher urine calcium excretion, lower percentage calcium retention and lower plasma phosphate levels than those given regimenY. These differences were apparent by day 7 and persisted after day 10. In infants given regimen Y, mean calcium retention from admission to day 7 was 3.9 mmol/kg, and after day 10 was 0.9 mmol/kg/day. 2. In the first 48 hours, urine output and creatinine clearance varied widely and were lower in infants with higher oxygen requirements at 48 hours. Ten babies had severe oliguria with outputs less than 10 mL/kg/day. Creatinine clearance was directly related to gestational age, mean arterial blood pressure, and plasma protein concentrations on admission. After 48 hours, urine output and creatinine clearance increased considerably. 3. In the first 48 hours, metabolic acidosis was produced by increased plasma non‐protein metabolisable acid concentrations, which were associated with low creatinine clearances, and were thought to be due to lactic acid accumulation in response to decreased tissue perfusion. At 7 days, metabolic acidosis was of similar severity but was produced by decreased plasma non‐metabolisable base concentrations, caused by increased urine loss of net base, and not directly by IVN. 4. A simple model was constructed for either estimating the net movement of a substance into or out of the extracellular fluid (ECF) space, referred to as production or uptake respectively, or for estimating change in the fraction of body weight made up by ECF, referred to as ECF fraction. 5. Hyperkalaemia developed in 5 infants at 48 hours, and was caused by a combination of severe oliguria and high rates of potassium production. Potassium production was directly related to urea production, which varied widely over the first 48 hours, low rates being found i...

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Section: Discussionmentioning

confidence: 99%

Mineral Balance Studies in Sick Preterm Intravenously Fed Infants during the First Week after Birth

Aiken

Sherwood²,

Kenney³

et al. 1989

Acta Paediatrica

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“…After subcutaneous injection in neonates, a constant vol of distribution is observed for 3 to 12 h (29). These data led most investigators to select a single blood sample, obtained 3 h after administration of bromide, to calculate the bromide space (23,(29)(30)(31)(32)(33)(34), although there was no evidence that stabilization of plasma bromide concentrations did not occur earlier after intravenous injection. In the past, we chose to use 1 h as a convenient time of sampling in both human and baboon neonates (24,(35)(36)(37)(38)(39)(40)(41).…”

Section: Discussionmentioning

confidence: 99%

Dilution Kinetics of Chemicals Used for Estimation of Water Content of Body Compartments in Perinatal Medicine

et al. 1989

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PAH, p-aminohippurateNumerous studies of perinatal physiology, metabolism, nutrition, and pathologic conditions require estimation of the fluid content of various body compartments. As direct volumetric determinations are not possible in vivo, less direct methods must be relied upon to obtain an acceptable estimate. The most commonly used techniques involve a principle developed by Fick. Fick's principle states that the fluid content (V) of a given space may be calculated following the administration of a dye or chemical into that space if the exact amount (Q) of substance injected and its concentration (C) in the fluid of the space are Rece~ved August 15, 1988; accepted November 22, 1988 known, or V = Q/C. The dye or chemical must have five main properties: It must I ) be harmless to the organism; 2) be easily measurable; 3) diffuse evenly and within a predictable period of time throughout its vol of distribution; 4) have no effect on fluxes of fluids across membranes; and 5 ) neither be metabolized nor leave the space for which the vol is being measured for the duration of the study. This last requirement is seldom met. If, however, the decrease in dye concentration with time follows a straight line, extrapolation of that line to time 0 (y-intercept or Co) still allows a vol determination to be made, or V = Q/Co. In that case, the rate at which the substance escapes from its vol of distribution, be it by metabolism or excretion, may be also calculated (slope of the concentration versus time line).In cases where all four criteria are met, the marker diffuses as soon as it is administered to reach an even concentration throughout its vol of distribution. In cases where the fourth criterion is not met, two phenomena occur simultaneously as soon as the marker is administered. First, the marker diffuses to reach an even concentration throughout its vol of distribution; second it is being cleared from its assigned space. To interpret the data correctly, it is important to determine at what point in time equilibration is complete and the behavior of the marker concentration thereafter, i.e. the kinetics of the marker. Yet kinetic data have often been disregarded or remained buried in the investigators' laboratory data books and are scarce in the relevant literature. Also, in human perinatal medicine, there are ethical and practical limitations on the number and vol of body fluid samples that may be obtained. In this report, we have made use of the baboon (Papio cynocephalus), whose fetoplacentouterine unit and neonatal physiology and metabolism are very similar to those of Homo sapiens, to determine the kinetics of six markers: PAH (amniotic fluid vol), inulin (amniotic fluid vol), antipyrine (total body water), H2'" (total body water), bromide (extracellular water) and T-1824 (plasma vol). From these kinetics, precise recommendations may be made regarding optimal time and method of amniotic fluid or blood sampling. MATERIALS A N D METHODSPAIf and inulin dilution. The kinetics of PAH and inulin dilution in amniotic f...

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Water Metabolism in the Fetal-Placental Unit

Wintour¹

1991

Principles of Perinatal-Neonatal Metabolism

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Increased extracellular water volume associated with hyponatremia at birth in premature infants

Cited by 23 publications

References 13 publications

Mineral Balance Studies in Sick Preterm Intravenously Fed Infants during the First Week after Birth

Mineral Balance Studies in Sick Preterm Intravenously Fed Infants during the First Week after Birth

Dilution Kinetics of Chemicals Used for Estimation of Water Content of Body Compartments in Perinatal Medicine

Water Metabolism in the Fetal-Placental Unit

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