Assuntos
Mortalidade Infantil , Recém-Nascido de Baixo Peso/fisiologia , Surfactantes Pulmonares/uso terapêutico , Síndrome do Desconforto Respiratório do Recém-Nascido/prevenção & controle , Displasia Broncopulmonar/epidemiologia , Causas de Morte , Feminino , Seguimentos , Humanos , Recém-Nascido , Masculino , Prevalência , Estudos Prospectivos , Análise de Regressão , Taxa de SobrevidaRESUMO
We hypothesized that parenteral delivery of calcium and phosphorus in a ratio of 1.7:1 would promote retention of these minerals and decrease urinary phosphorus excretion, and that delivery of increased amounts of this ratio would result in higher retentions. Serum levels and retention of calcium and phosphorus were measured as calcium intake was increased from 36 to 76 mg/kg/day in 10 mg increments and as phosphorus intake was adjusted to maintain the 1.7:1 ratio. Five different infants were studied at each of the five levels. The amounts of calcium and phosphorus retained increased steadily and at level 5 were 71.8 +/- 1.2 mg/kg/day and 40.9 +/- 1.7 mg/kg/day, respectively. Over the five levels the average percent calcium retention was 91.4 +/- 4.2 and the average percent phosphorus retention was 89.1 +/- 7.7. The provision of parenteral calcium and phosphorus in a 1.7:1 ratio resulted in a balanced retention of both minerals over the range studied. The use of this calcium/phosphorus ratio appears to be appropriate for the preterm infant receiving total parenteral nutrition.
Assuntos
Cálcio/administração & dosagem , Recém-Nascido Prematuro , Nutrição Parenteral Total , Fósforo/administração & dosagem , Cálcio/farmacocinética , Humanos , Recém-Nascido de Baixo Peso/metabolismo , Recém-Nascido , Recém-Nascido Prematuro/metabolismo , Fósforo/farmacocinéticaRESUMO
The pharmacokinetics of furosemide were studied longitudinally during long-term administration in 10 very low birth weight infants with bronchopulmonary dysplasia. Mean birth weight of the infants was 829 +/- 217 g, mean gestational age at birth was 26.6 +/- 2.9 weeks, and mean postnatal age at the start of therapy was 2.4 +/- 1.0 weeks. Serial determinations of furosemide pharmacokinetic parameters were performed during 2 weeks to 3 months of long-term therapy. Plasma half-life was prolonged in infants less than 31 weeks postconceptional age (gestational + postnatal age), frequently exceeding 24 hours. All infants less than 29 weeks postconceptional age whose dosing schedule was once every 12 hours accumulated furosemide to potentially ototoxic levels. Furosemide renal clearance increased and plasma half-life decreased in association with increasing postconceptional age. Furosemide secretory clearance was very low in patients less than 31 weeks postconceptional age, resulting in a reliance on glomerular filtration to deliver drug to its main site of action within the lumen of the loop of Henle. Thus elevated plasma levels may be required to ensure adequate luminal delivery and adequate diuresis in these infants with low secretory clearance. Nevertheless, the current dosing schedule (once every 12 hours) of furosemide should be modified to once every 24 hours in infants of low postconceptional age to avoid possible toxic effects.
Assuntos
Displasia Broncopulmonar/tratamento farmacológico , Furosemida/farmacocinética , Recém-Nascido de Baixo Peso/metabolismo , Fatores Etários , Displasia Broncopulmonar/metabolismo , Furosemida/administração & dosagem , Meia-Vida , Humanos , Recém-Nascido , Rim/metabolismo , Taxa de Depuração MetabólicaRESUMO
Sodium balance was studied in 17 consecutively admitted neonates weighing less than 1,200 gm at birth. Infants whose gestation was less than or equal to 30 weeks were sicker and were in markedly negative sodium balance on day 3 (-9.25 mEq/kg day), despite a high sodium intake (7.22 mEq/kg/day). This negative balance was the result of a high fractional sodium excretion and resulted in hyponatremia in six (50%) of the patients. By day 8 these immature infants were in positive sodium balance, although fractional sodium excretion and daily sodium requirements remained high. More mature infants (greater than 30 weeks gestational age) were in positive sodium balance on both days 3 and 8. Creatinine clearance did not differ significantly between groups on either day 3 or 8 but increased within each group during the study period. These data suggest that the daily sodium requirement of immature sick infants may be much higher than was previously suggested.