A prospective randomized trial comparing continuous versus intermittent feeding methods in very low birth weight neonates.

OBJECTIVE: To compare the effects of continuous versus intermittent feedings on physical growth, gastrointestinal tolerance, and macronutrient retention in very low birth weight infants ( < 1500 gm). STUDY DESIGN: Very low birth weight neonates stratified by birth weight were randomly assigned to either continuous (24-hour) or intermittent (every 3 hours) nasogastric feedings. Feedings with half-strength Similac Special Care formula were initiated between day 2 and 3 and were advanced isoenergetically to goal. Daily weights, volume/caloric intakes, weekly anthropometric and dynamic skin-fold thickness measurements, and data on feeding milestones and clinical complications were collected. Nitrogen, carbohydrate, and fat balance studies were performed on a subset of male subjects. RESULTS: Eighty-two neonates with birth weights between 750 and 1500 gm who were born between 27 and 34 weeks of gestation were randomly assigned to continuous (n = 42) and intermittent (n = 40) feeding groups. There were no significant differences in baseline demographics and severity of respiratory distress between groups. There were no significant differences in days to regain birth weight, days to full enteral feedings, days to discharge, and discharge anthropometric measurements between continuously fed and intermittently fed infants, both when evaluated together and according to 250 gm weight intervals. Retention rates of nitrogen, fat, total carbohydrate, and lactose were comparable in the continuously fed (n = 17) and intermittently fed (n = 13) male neonates. Very low birth weight neonates who were fed continuously did not have feeding-related complications. CONCLUSION: Very low birth weight infants achieve similar growth and macronutrient retention rates and have comparable lengths of hospital stay whether they are fed with continuous or intermittent feedings.

Total body electrical conductivity measurements: an evaluation of current instrumentation for infants.

Quantitation of the body's fat and learn masses is an important component of nutritional assessment. Such measurements, however, are difficult to conduct routinely in infants due to the numerous limitations of traditional methods. The application of total body electrical conductivity measurements for quantitating fat-free mass (FFM) overcomes many of these limitations. The instruments required to perform these measurements in pediatric patients (HP-2) have recently become commercially available, but their measurement performance has not been evaluated. In these studies, we compared the precision, day-to-day variability, and magnetic field profile of three HP-2 instruments. We also derived a new calibration equation that relates the FFM to the total body electrical conductivity measurement in piglets, and compared it with an equation (provided currently by the manufacturer) derived on a prototype instrument. The performance of the instruments was generally similar, although a significant difference in the magnetic field of one instrument was identified. The coefficient of variation of inanimate phantom measurements varied from +/- 0.2 to +/- 0.5%, and the day-to-day variability was generally similar. Such measurement error is significant (+/- 0.035 to +/- 0.078 kg FFM) for small subjects. The new calibration equation was similar to the original equation; therefore, all the data were pooled to generate a new equation that is linear at least to 10 kg. Thus, the HP-2 total body electrical conductivity instruments, which can be safely and easily used to measure FFM and fat in infants through 1 y of age, proved to be reliable and precise, and results obtained from different instruments can be confidently compared.

Neonatal morphometry. Relation to obstetric, pediatric, and menstrual estimates of gestational age.

OBJECTIVE: To determine gestational age-dependent neonatal morphometrics based on last menstrual periods (LMPs), Ballard examinations, and obstetric estimates of gestational age. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional survey of 38,818 live-born neonates at a tertiary care center in Detroit, Mich. SELECTION PROCEDURES: Consecutive sample of all viable, structurally normal, singleton neonates delivered at Hutzel Hospital from 1984 through 1991. MEASUREMENTS/MAIN RESULTS: Neonatal weights, lengths, and head circumferences were recorded at birth. Gestational age-dependent morphometrics were based solely on LMPs and compared with those based on obstetric estimates (using LMPs corrected by fetal ultrasound). Ballard examination had an 85.4% concurrence (within 14 days) with obstetric estimates of gestational age, but only a 69.9% (P less than .0001) agreement with LMP. Dating only by LMP significantly overestimated the prevalence of prematurity (odds ratio [OR], 1.3; 99% confidence interval [CI], 1.3 to 1.4) and postmaturity (OR, 5.0; 99% CI, 4.6 to 5.4), distorting apparent growth patterns, especially for preterm neonates. In contrast to previous studies based solely on LMPs, morphometric measurements increased beyond 40 weeks when dated by obstetric estimates. CONCLUSIONS: Gestational age-dependent neonatal morphometrics should not be based solely on LMPs.

Determination of body composition in growing rats by total body electrical conductivity.

Total body electrical conductivity (TOBEC), measured with an Em-Scan SA-1 analyzer, was evaluated as a means of estimating fat-free mass and total body water content noninvasively in small laboratory animals. Ninety-four rats whose weight ranged from 5.53 to 170.84 g at 0-50 days of age were studied. The animals were killed by intraperitoneal injection of a pentobarbital overdose. After weight, crown-rump length (CRL) and TOBEC were measured, and the animals were minced with scissors and desiccated to constant weight in a convection oven. Fat was extracted by multiple bathings in petroleum ether followed by Soxhlet extraction. Fifty-four rats were used to determine the relation between fat-free mass (FFM), total body water (TBW), and TOBEC# (E) by regression analysis. The best correlations were observed between FFM and (E x CRL)1/2 (r = 0.995, p less than 0.0001). Forty rats were used to determine the predictive value of TOBEC estimates. With this instrument, TOBEC tended to underestimate FFM by an average of 3.9% and TBW by 5.3%. Accuracy was questionable for animals smaller than 13 g and TOBEC did not provide useful estimates of total body fat. Subject to these limitations, TOBEC instruments should prove to be useful for sequential in vivo estimations of body composition during growth and development of small animals.

Effects of thiazide diuretics on the lipid profile of infants with bronchopulmonary dysplasia.

Hyperlipidemia has been reported in some infants with bronchopulmonary dysplasia (BPD) who received thiazides for extended periods. In this prospective, controlled trial, we studied 17 infants with BPD who received diuretic therapy and 26 control infants who did not receive diuretics. Plasma triglycerides, total cholesterol and high-density lipoprotein (HDL) cholesterol were measured enzymatically prior to onset of diuretic therapy in the study group of infants and on the day of recruitment into the study in control infants, and every 2 weeks thereafter. Plasma low-density lipoprotein cholesterol concentrations were calculated. At the end of 4 weeks, plasma lipid concentrations were comparable in both groups of infants except for significantly higher plasma HDL cholesterol concentrations observed in infants who received chlorothiazide (39 +/- 15 vs. 30 +/- 6 mg/dl, p less than 0.05). Short-term administration of chlorothiazide to infants with BPD is not associated with clinically significant changes in plasma lipid concentrations.

Estimation of extracellular fluid volume by bromide dilution in infants less than 1000 grams birth weight.

We measured extracellular fluid volume by bromide dilution within 12 h of birth in 32 infants less than 1000 g birth weight. Mean (+/- S.D.) birth weight and gestational age were 763 +/- 123 g and 26 +/- 1 week, respectively. Mean extracellular fluid volume was 360 +/- 86 ml (477 +/- 107 ml/kg). These results are similar to extracellular fluid volume estimates from previous carcass analysis data. Wide variability is observed with both methods suggesting that biologic variability may be important.

Biomedical technology: to use or not to use?

The past 30 years have seen tremendous advances in biomedical technology that have changed dramatically the practice of medicine in general, of neonatology in particular. All changes have not been for the best, however. The price tag has been especially steep, but there have been adverse effects on the quality of medicine as well. The reasons we rely on high technology, its risks and pitfalls, and our future handling of decisions regarding using or not using biotechnology deserve careful consideration, including financial factors that physicians have been loath traditionally to address. If the medical profession is to avoid becoming enslaved to technology, our future decisions must be better informed, more rational, and based on more scientific facts than they have been in the past. Above all, physicians must avoid becoming mere technicians at the expense of the traditional humanistic approach to patient care.

Serial estimates of body water content and distribution during the first postnatal month in baboons.

Water content of the various body compartments was estimated serially during the first postnatal month in six term baboon neonates. In absolute volumes (mL), total body water, intracellular water, and plasma volume all increased linearly with body weight and postnatal age, although the effect of weight was predominant. In proportion to body weight (mL/kg), total body water, intracellular water, and plasma volume increased linearly with postnatal age whereas extracellular water and red cell volume decreased. There was no linear relation between the proportions of any of the water volumes and body weight.

Autospec: computerized processing of the data output from a spectrophotometer in a biochemical laboratory.

Autospec was designed to acquire data output from a Beckman DU series 60 spectrophotometer and to process these data with an IBM or IBM-compatible computer. It functions in conjunction with the Beckman DU Data Capture and Lotus 1-2-3 softwares. Autospec automatically stores data produced by the spectrophotometer, determines standard curves and calculates unknown concentrations of the substance being assayed. The principal features of Autospec are simplicity of use, adaptability and flexibility, minimal intervention from the operator, standardized print-outs of all data in tabular and graphic forms, accuracy of computations, speed of operation, and ease of storage and back-up of data files.

Dexamethasone effects on the hospital course of infants with bronchopulmonary dysplasia who are dependent on artificial ventilation.

A randomized double-blind placebo-controlled trial was conducted to evaluate the effects of enterally administered dexamethasone on the hospital course of infants with bronchopulmonary dysplasia. A total of 23 infants with a birth weight less than 1500 g who were dependent on artificial ventilation 3 to 4 weeks of age received dexamethasone (n = 12) or saline placebo (n = 11). Dexamethasone (0.5 mg/kg per day) was given in tapering doses for 7 days followed by hydrocortisone (8 mg/kg per day) which was progressively reduced for a total of 17 days of therapy. Infants who received dexamethasone required less oxygen on days 8 and 17 (P less than .05) and were more likely to extubate 8 days after therapy than infants in the control group (respectively 8/12 vs 3/11 infants, P less than .05; P = .12 after Yates correction). The use of dexamethasone significantly shortened median duration of mechanical ventilation (4 vs 22 days, P less than .05) but had no effect on length of oxygen therapy, hospitalization, home oxygen therapy, occurrence and severity of retinopathy of prematurity, rate of growth, and mortality. No significant complications resulted from dexamethasone therapy. Measurements of plasma dexamethasone levels confirmed the absorption of drug from the gastrointestinal tract (23.7 ng/mL in dexamethasone vs 4.6 ng/mL in the control group, P less than .05). Dexamethasone administration resulted in short-term improvements in pulmonary function but did not ameliorate the hospital course of infants with bronchopulmonary dysplasia.

Deuterium enrichment of plasma determined by nuclear magnetic resonance spectroscopy: dilution kinetics of 2H2O and estimation of total body water.

We demonstrate the feasibility of quantifying the abundance of 2H in plasma by nuclear magnetic resonance (NMR) spectroscopy. After adding internal standard (tert-butyl-d9 alcohol) to deproteinized plasma samples containing 2H2O, we determined the ratio of NMR peak areas for 2H2O and tert-butyl-d9 alcohol. This peak-area ratio was directly proportional to the exogenous 2H enrichment of plasma (difference between measured and naturally occurring 2H) between 0 and 0.272 atom % (r = 0.999). The coefficient of variation was 1.34% at an exogenous enrichment of 0.136 atom %. We applied this method to a study of the dilution kinetics of 2H2O to determine the optimal time and method of blood sampling for estimation of total body water content. The 2H enrichment of plasma stabilized by 4 h after intravenous injection of 2H2O, 1 g/kg of body weight, and fluctuated within 2-4% of the 4- to 8-h mean thereafter.

Effect of extracorporeal membrane oxygenation on body water content and distribution in lambs.

Water content of the various body compartments were estimated immediately after beginning extracorporeal membrane oxygenation (ECMO), and daily thereafter for 3 days, in seven healthy 2-month-old lambs. Total body water, extracellular water, and plasma volume were estimated simultaneously by 18O, bromide, and T-1824 dilution, respectively. Volumes of intracellular water, interstitial water, blood, and red cells were calculated from the experimental estimates. No statistically significant changes occurred in the water content of the various body compartments in relation to duration of ECMO. The data suggest that water retention, clinically noted in human neonates treated with ECMO for persistent pulmonary hypertension, may be related to the primary disease process and/or its medical management, rather than to ECMO.

Tolerance of fat emulsions in very low birthweight neonates: effect of birthweight on plasma lipid concentrations.

Plasma concentrations of various lipid fractions (total lipids, free glycerol, true triglycerides, free fatty acids, and cholesterol) were studied in 20 normally grown neonates ranging in birthweight from 820 to 1500 gm and in gestational age from 28 to 34 weeks. They were subdivided into three weight categories: 750 to 999, 1000 to 1249, and 1250 to 1500 gm. A lipid emulsion was infused at a constant rate over 24 hours, beginning with an hourly infusion rate of 0.04 gm/kg and increasing each day by 0.04 gm/kg up to a maximum of 0.16 gm/kg. Neonates who weighed less than 1000 gm had higher mean plasma concentrations of total lipids and free glycerol at hourly infusion rates of 0.08 and 0.16 and of triglycerides and free fatty acids at hourly infusion rate of 0.16 gm/kg than their heavier peers. These data suggest that extreme caution be used when administering parenteral fat emulsions to neonates who weigh less than 1000 gm and that we need to monitor plasma closely for signs of hyperlipemia.

Placental transfer of vitamin K1 in preterm pregnancy.

Seventy-eight women at earlier than 35 weeks' gestation with premature rupture of membranes and/or preterm labor were randomly assigned to receive either 10 mg vitamin K1 intramuscularly (IM) or no treatment. If delivery did not occur within 4 days, the dose of vitamin K1 was repeated. Women whose pregnancies continued beyond 8 days received 20 mg of vitamin K1 orally every day until the end of the 34th week or until delivery, whichever occurred earlier. The median maternal plasma vitamin K1 level was significantly higher in treated than in untreated subjects (11.592 versus 0.102 ng/mL; P less than .001). The median cord plasma levels were 0.024 ng/mL in the treated group and 0.010 ng/mL in the controls, a significant difference (P = .046). Median plasma vitamin K1 levels were comparable in mothers receiving the drug by the IM route only and by both the IM and oral routes (10.533 versus 11.928 ng/mL; P = .460). The infants of the latter group, however, had significantly higher median cord plasma levels (0.42 versus 0.017 ng/mL; P less than .001). There was no correlation between cord plasma vitamin K1 levels and gestational age or duration of maternal supplementation with vitamin K1. We conclude that, in preterm pregnancies, vitamin K1 crosses the placenta slowly and to a limited degree.

Effect of uncomplicated pregnancy on body water content and distribution in baboons.

Body water content and distribution were estimated before, during, or after 32 pregnancies in baboons. Water content of the various compartments (in liters) correlated with body weight in both nonpregnant and pregnant baboons, and with length of gestation in pregnant baboons. In proportion to body weight (in ml/kg), most water compartments did not change significantly with length of gestation. Mean plasma volume and blood volume were higher during pregnancy than before or after.

Correlation of commonly used measures of intrauterine growth with estimated neonatal body fat.

Several morphometric measures have been used to identify infants at greatest risk from aberrant intrauterine growth. 119 near-term infants were studied to answer the more basic question of how well measures, such as birthweight percentile, ponderal index, the body mass index and the weight/length ratio reflect body fat in the neonate. Skinfold thicknesses were measured as an estimate of fat stores. Multiple regression analysis revealed that the weight/length ratio showed the strongest correlation with relative adiposity, explaining 52% of the variance. Further, sequential exponentiation of the crown-heel length in body mass index and ponderal index decreased the correlation with estimates of body fat. The simple weight/length ratio, exhibiting both a close correlation with body fat and independence of gestational age, race and sex, in near-term infants may be the best morphometric measure of the nutritional component of intrauterine growth in the neonate.

Maternal blood pressure and fetal ultrasonography in normal baboon pregnancies.

Pregnancy in baboons is characterized by lower systolic, diastolic, and mean blood pressures than in the nonpregnant state. As pregnancy progresses, diastolic and mean pressures tend to increase whereas systolic pressure remains low. Sonographic measurements of fetal growth follow a sigmoid pattern, but their increase in relation to length of gestation approximates a straight line between 6 and 21 weeks of gestation (23 to 84% of term).

Simultaneous estimation of neonatal total body water by antipyrine and H2(18)O dilution.

Total body water was estimated simultaneously by dilution of antipyrine (antipyrine space; APS) and H2(18)O (18O-space; 18OS) in 5 baboon neonates and 2 two-month-old lambs (total of 14 studies). Calculations of 18OS were made either from a single plasma delta 18O measured 4 h after injection of the marker (18OS4) or by extrapolation to time zero of several plasma delta 18O obtained at precisely timed interval (18OS0). Mean (+/- SD) 18OS4 was on the average 23% lower than mean 18OS0 (796 +/- 70 ml/kg vs. 650 +/- 67 ml/kg, p less than 0.001). Mean APS was not statistically different from mean 18OS0 (664 +/- 127 ml/kg vs. 658 +/- 57 ml/kg), but APS ranged from 41% lower to 30% higher than 18OS0. These data and information from the literature suggest that antipyrine is of doubtful reliability and should be abandoned as a marker for total body water.

Maternal administration of vitamin K does not improve the coagulation profile of preterm infants.

The effect of maternal administration of vitamin K1 on cord blood prothrombin time, activated partial thromboplastin time, activity of factors II, VII, and X, and antigen levels of factors II and X in infants less than 35 weeks' gestation was evaluated. Pregnant women in preterm labor were randomly assigned to receive 10 mg of vitamin K1 intramuscularly or no injection. If delivery did not occur in 4 days, the dose of vitamin K1 was repeated. Women who continued their pregnancy 4 days beyond the second dose received 20 mg of vitamin K1 orally daily until the end of the 34th week of gestation. The birth weights of infants ranged from 370 to 2550 g and gestational age ranged from 22 to 34 weeks. The prothrombin time, activated partial thromboplastin time, factors II, VII, and X activity, and factors II and X antigen levels were not statistically different in either group of infants. Intraventricular hemorrhage occurred in 25 of 51 control infants and 25 of 47 vitamin K-treated infants. More control infants had grade III intraventricular hemorrhage on day 1 (P = .032), but on day 3 and 14 of life, the severity of intraventricular hemorrhage was comparable in both groups. Infants in whom an intraventricular hemorrhage developed were significantly smaller, younger, and more critically ill than infants without intraventricular hemorrhage. Administration of vitamin K1 to pregnant women at less than 35 weeks' gestation does not improve the hemostatic defects nor does it reduce the incidence or severity of intraventricular hemorrhage in their infants.