Perinatal bacterial infection after prolonged rupture of amniotic membranes: an analysis of risk and management.

Chi-square and logistic stepwise multiple regression analysis of perinatal determinants of infant bacterial infection following prolonged rupture of amniotic membranes for 24 hours or more prior to delivery was applied in 33 infected infants and 66 matched control infants from the NINCDS Collaborative Project. In order of statistical significance, the most important variables were placental inflammation (P = 0.002), gestational age less than 34 weeks (P = 0.008), gestational age 34 to 37 weeks (P = 0.013), male sex (P = 0.015), Apgar score less than 6 at 5 minutes (P = 0.023), and clinical amnionitis (maternal fever, fetal tachycardia, or amniotic or gastric fluid leukocytes or bacteria) (P = 0.044). Duration of labor during PROM, race, and maternal age and parity were insignificant. Using these predictive variables, identification of infected infants for either microbial surveillance (superficial and systemic cultures) or microbial surveillance and anticipatory antibiotic therapy (discontinued after 3 days of negative cultures) was highly significant (P = 0.0001). Incorporating these variables and derived coefficients from multivariate analysis, a mathematical model was used for evaluation and prediction of perinatal bacterial infection with a sensitivity of 82% and specificity of 70%. Analysis of 46 infants prior to and 310 infants after implementation of this process at Harbor-UCLA Medical Center indicated significant improvement in the appropriate management of these infants at risk (from 59% to 87% of the population, P less than 0.05). Inappropriate antibiotic therapy decreased from 35% to 10% (P less than 0.05). In the absence of a shift in the median days of hospitalization of non-PROM infants, determination of the grand median days of PROM infant hospital stay showed a decrease (P less than 0.01) after initiation of this evaluation and management scheme.

Plasma catecholamine concentrations in infants at birth and during the first 48 hours of life.

A radioenzymatic assay was used to measure plasma concentrations of the catecholamines, norepinephrine, and epinephrine in the perinatal period. Samples were obtained at birth from the umbilical artery and vein of infants born by vaginal and by cesarean section delivery; from peripheral venous samples of normal infants during the first 48 hours of life; and from peripheral venous samples of mothers prior to delivery. Concentrations of NE and E were elevated in umbilical samples, with umbilical artery levels exceeding umbilical venous concentrations. Umbilical plasma CAT concentrations were similar in vaginal and cesarean section delivered infants. Plasma concentrations of NE consistently predominated over E in all samples from neonates. Plasma CAT concentrations rapidly fell from cord levels within 15 minutes of delivery and remained at a lower plateau during the first three hours of life. By 12 hours of age plasma CAT concentrations fell to the levels of supine adult resting concentrations. Maternal plasma CAT concentration prior to delivery demonstrated a predominance of E over NE. These elevations of plasma CAT in the early neonatal period may play a rola in nonshivering heat production as well as in cardiovascular alterations associated with birth.

The effects of large volume intravenous fluid infusion on neonatal renal function.

Twenty healthy infants weighing less than 2,000 gm were studied at low (3.6 ml/kg/hr) or high (10.3 ml/kg/hr) rates of intravenous infusion. Inulin clearance determined by the constant infusion method was greater at the high rate of infusion (p = less than 0.05). Inulin clearance in two groups of infants over 2,000 gm studies at the same low or high rates of infusion did not increase at the higher rate of infusion. Since the GFR in infants less than 2,000 gm depends partially on the rate of intravenous infusion, small, healthy preterm infants may benefit from a rate of fluid administration greater than the low rate. When studies at low and high rates of infusion were compared in the 20 infants less than 2,000 gm, the fractional urinary sodium excretion increased with the increased fluid load. Delivery of fluid from the proximal tubule (CH2O =Na per dl GFR) increased (p less than 0.005). Free-water clearance and the absolute volume of urine increased at the high rate of infusion. These data indicate that the healthy preterm infant less than 2,000 gm, like the adult, compensates by increasing free-water clearance and urine volume when challenged with a large fluid load. Although fluid changes of short duration are appropriately handled, the effect of continuous rapid infusion on water and sodium balance in infants of this size remains to be determined.