Prone and supine positioning effects on energy expenditure and behavior of low birth weight neonates

The effect of body position (supine v prone) on energy expenditure and behavior of 42 healthy low birth weight (920 to 1,760 g) infants was evaluated in 66 studies. Each infant was randomly assigned to the supine or prone position for the first three-hour epoch; the position was reversed for the second three-hour epoch. The difference in energy expenditure and the percentage of time in active sleep, quiet sleep, and wakefulness between the two positions was computed. The median difference (supine minus prone) in overall energy expenditure between positions was +3.1 kcal/kg/d (interquartile range 0.6 to 6.5; P less than .001). When only periods of active sleep were analyzed, the median difference in energy expenditure remained significant, the supine position being higher than prone by +2.6 kcal/kg/d (interquartile range 0.1 to 4.8; P less than .001). In the supine position, the time awake was 5.7% higher (interquartile range 1.8 to 17.4; P less than .001) than in the prone position. The percentage of time in active sleep was not significantly different between the positions, hence quiet sleep decreased in the supine position. In summary, when low birth weight infants are changed from the supine to the prone position, energy expenditure decreases, time spent in quiet sleep increases, and time spent awake decreases. These data suggest that prone is the position of choice for the low birth weight infant.     

Whole body protein synthesis and energy expenditure in very low birth weight infants

The aim of the present work was to study whole body protein synthesis and breakdown, as well as energy metabolism, in very low birth weight premature infants (less than 1500 g) during their rapid growth phase. Ten very low birth weight infants were studied during their first and second months of life. They received a mean energy intake of 114 kcal/kg X day and 3 g protein/kg X day as breast milk or milk formula. The average weight gain was 15 g/kg X day. The apparent energy digestibility was 88%, i.e. 99 kcal/kg X day. Their resting postprandial energy expenditure was 58 kcal/kg X day, indicating that 41 kcal/kg X day was retained. The apparent protein digestibility was 89%, i.e. 2.65 g/kg X day. Their rate of protein oxidation was 0.88 g/kg X day so that protein retention was 1.76 g/kg X day. There was a linear relationship between N retention and N intake (r = 0.78, p less than 0.001). The slope of the regression line indicates a net efficiency of N utilization of 67%. Estimates of body composition from the energy balance, coupled with N balance method, showed that 25% of the gain was fat and 75% was lean tissue. Whole body protein synthesis and breakdown were determined using repeated oral administration of 15N glycine for 60-72 h, and 15N enrichment in urinary urea was measured. Protein synthesis averaged 11.2 g/kg X day and protein breakdown 9.4 g/kg X day. Muscular protein breakdown, as estimated by 3-methylhistidine excretion, contributed to 12% of the total protein breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)     

Domiciliary care of low birth weight neonates

A WHO sponsored prospective community based study of ‘Risk Approach and Intervention Strategy in MCH Care’ was started in a rural field practice area attached to B.J. Medical College, Pune, catering for 47,000 population spread over 22 villages. For implementation of risk approach strategy from pregnancy to early childhood, information about biological and sociocultural factors was collected. Birth weight of every newborn child was recorded to identify ‘at risk’ baby weighing less than 2500 gm. Relative risk and community attributable risk for these low birth weight neonates were computed. Domiciliary care given to the new-, born can reduce the risk by preventing infections, maintaining adequate nutrition and protecting the baby from adverse environmental influences, by simple measures feasible at village level by supporting beneficial, traditional cultural practices and introducing new techniques.     

Vancomycin pharmacokinetics in very low birth weight neonates

The pharmacokinetics of vancomycin hydrochloride was studied in 12 very low birth weight infants. The gestational age (mean +/- SD) was 25.9 +/- 1.3 weeks and body weight was 769.2 +/- 151.5 g at the time of initiation of the study. Vancomycin was infused over a period of 60 minutes in a dosage of 14.2 +/- 3.2 mg/kg once daily in 10 patients, twice daily in 1 patient and every 36 hours in 1 patient for a mean of 10.5 +/- 4.9 days. Serial blood samples were obtained and the concentration time data were fitted to a one-compartment open model using the ADAPT computer program. A significant positive correlation was found between postconceptional age and vancomycin clearance (P less than 0.005) and between vancomycin elimination half-life and plasma creatinine (P less than 0.01). A negative correlation existed between plasma creatinine and vancomycin clearance (P less than 0.005), between postconceptional age and plasma creatinine (P less than 0.005) and between vancomycin half-life and postconceptional age (P less than 0.01). On the basis of these findings a vancomycin dosage of 15 mg/kg every 24 hours for infants less than 1000 g should yield concentrations within the accepted therapeutic range. This susceptible population requires frequent monitoring of vancomycin concentrations because of the high degree of interpatient variability and the continuous maturation of renal function.     

Cefotaxime and desacetylcefotaxime pharmacokinetics in very low birth weight neonates

The single-dose pharmacokinetics of cefotaxime (CTX) and desacetylcefotaxime (dCTX) after a 50.0 mg/kg intravenous dose were evaluated in 18 very low birth weight neonates (13 male; 1015.6 +/- 349.8 gm; 28.4 +/- 2.4 weeks gestational age) during the first week of life. Microanalytic high-performance liquid chromatography was used to quantitate both CTX and dCTX from serum. A two-compartment open model best characterized the disposition of CTX during a 24-hour post-dose period. The disposition of dCTX was adequately characterized by a one-compartment model. The elimination half-life, apparent steady-state volume of distribution, and total body clearance of CTX (mean +/- SEM) were 4.44 hours, 0.461 +/- 0.027 L/kg, and 0.074 +/- 0.003 L/hr/kg, respectively. Peak concentrations (mean +/- SD) of dCTX (17.96 +/- 5.54 mg/L) occurred at 0.6 to 8.3 hours (5.9 +/- 1.9 hours) after CTX administration, and the apparent elimination half-life of dCTX was 9.36 hours. Comparison of CTX and dCTX pharmacokinetic parameters between very low birth weight neonates who weighed less than 1000 gm (n = 9; 703.3 +/- 46.6 gm; 27.0 +/- 0.8 weeks gestational age) and greater than or equal to 1000 gm (n = 9; 1328.8 +/- 48.6 gm; 29.8 +/- 0.5 weeks gestational age) revealed no significant differences, but significant linear correlations were found between gestational age and weight versus CTX half-life and total body clearance. Because of the prolonged clearance of both CTX and dCTX in the very low birth weight neonate, a CTX dose of 50 mg/kg every 24 hours may provide effective serum concentrations for susceptible infections outside the central nervous system.     

Pharmacokinetics of intravenous immunoglobulin in very low birth weight neonates

We studied the pharmacokinetics of single doses of intravenous immunoglobulin (IVIG) of 1000, 750 and 500 mg/kg administered to 21 neonates with birth weights from 750 to 1500 g. No adverse effects were detected. Mean pharmacokinetic values for the large, intermediate and small dose groups, respectively, were: elimination half-life, 19.6, 28.7 and 22.1 days; clearance, 5.2, 5.6 and 3.7 ml/kg/day; volume of distribution, 151, 255 and 130 ml/kg. Mean peak IgG concentrations in serum were 1826, 1476 and 1257 mg/dl for the large, intermediate and small dose groups, respectively. Mean IgG on post-infusion Days 1 to 28 were similar for the intermediate and small dose groups but were higher in the larger dose group. Both large and intermediate doses achieved larger increases in IgG over preinfusion values (delta IgG) than the small dose. The differences in delta IgG between the large and intermediate doses were less notable. The wide variability observed indicates that individualization of intravenous immunoglobulin dosage will be required in these patients.     

Persistent bacteremia due to coagulase-negative staphylococci in low birth weight neonates

During a 6-month period in 1987, 13 low birth weight neonates without indwelling central intravascular catheters had persistent (positive blood cultures for greater than or equal to 6 days) coagulase-negative staphylococcal bacteremia despite adequate antibiotic therapy. Daily blood cultures remained persistently positive for a mean of 13 days (range 6 to 25 days). This group of infants was compared with other low birth weight infants with similar birth weights and nonpersistent coagulase-negative staphylococcal bacteremia, defined as two or more positive blood cultures accompanied by supporting clinical manifestations of sepsis. During this period, coagulase-negative staphylococcal represented 29% of all bacteremias, and 33% of coagulase-negative staphylococcal bacteremias were persistent. Other than soft tissue abscesses, none of the infants with persistent coagulase-negative staphylococcal bacteremia had a defined focus of infection. Abdominal distention (P = .001) and thrombocytopenia (P less than .03) occurred significantly more frequently in the patients with persistent coagulase-negative staphylococcal bacteremia than in those with nonpersistent bacteremia. Of the 13 patients with persistent coagulase-negative staphylococcal bacteremia, 2 received methicillin and 11 received vancomycin. No antibiotic tolerance to either antibiotic could be demonstrated. Serum concentrations of vancomycin far exceeded the minimum bactericidal concentration in all cases in which vancomycin was prescribed. No in vitro differences could be demonstrated between persistent and nonpersistent coagulase-negative staphylococcal strains for slime production, biotype, proteins from modified whole cell lysates developed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and opsonophagocytosis by adult neutrophils in the presence of pooled human sera. Additionally, plasmid profile analysis and phage typing revealed no common strain causing the persistent bacteremia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selenium deficiency in low birth weight neonates: an unrecognized problem

To determine whether selenium deficiency is common among low birth weight infants in our neonatal intensive care unit, we surveyed blood samples from healthy full-term and preterm infants born in our hospital over a 3-month period. Selenium was measured by electrothermal atomic absorption spectrometry. Glutathione peroxidase was measured in plasma by an automated method. Baseline (less than 72 hours postnatal) selenium concentration and glutathione peroxidase activity were significantly lower in low birth weight infants than in full-term babies. Sequential selenium analyses were obtained in 16 sick low birth weight neonates who remained in the intensive care nursery for up to 6 weeks because of lung disease. All were fed parenterally without supplemental selenium, with or without oral intake, for periods varying from 3 to 60 days. All had a marked decrease from baseline selenium levels, and values below the detection limit of our assay were found in seven infants. Selenium deficiency is much more common in small infants than is generally realized, but the clinical significance in neonates is poorly understood.     

T-tube ileostomy for intestinal perforation in extremely low birth weight neonates

To evaluate the results of use of T-tube ileostomy in selected cases of intestinal perforation in extremely low birth weight (ELBW) neonates. The records of 288 ELBW neonates treated at author’s institution, from 1998 to 2003 were retrospectively reviewed to identify neonates operated for intestinal perforation with T-tube placement. T-tube was inserted into the bowel through the site of perforation or proximally to the perforated gut via separate stab incision. T-tubes were used in five ELBW neonates (BW 600–900 g, gestational age 25–27 weeks) with intestinal perforation, in four of them at the time of primary surgery and in one neonate 8 days after primary anastomosis. All patients survived and there were no serious complications related to the T-tube insertion. Median duration of T-tube placement was 4 weeks (range 3–8 weeks), full enteral feeding after T-tube insertion was achieved in 4 weeks (range 1–6 weeks). All sites of T-tube insertion closed spontaneously. T-tube ileostomy is an effective and safe technique for treatment of selected cases of intestinal perforation in ELBW neonates. With respect to the hypoperistalsis of immature bowel, we recommend the use of T-tube in all cases of isolated intestinal perforation in ELWB neonates.     

Liver vitamin A reserves of very low birth weight neonates

This study assessed the liver vitamin A concentrations at birth in a group of very low birth weight neonates (n = 25) (less than 1500 g birth weight, less than 32 wk gestation), dying within 24 h of birth, prior to possible changes in vitamin A status induced by postnatal intervention. Serum concentrations of vitamin A and retinol-binding protein were also measured in 16 of these neonates. The mean (+/- SD) liver vitamin A concentration was 30.0 +/- 12.9 micrograms/g (range 2.0-49.0 micrograms/g). The mean (+/- SD) serum vitamin A concentration was 13.0 +/- 4.7 micrograms/dl (range 6.7-22.8 micrograms/dl). The mean (+/- SD) serum retinol-binding protein concentration was 2.2 +/- 0.8 mg/dl (range 1.5-4.8 mg/dl). Liver vitamin A, serum vitamin A, and serum retinol-binding protein concentrations did not correlate significantly with gestational age or birth weight. Linear regression analysis did not show a significant correlation between liver vitamin A, and serum vitamin A or retinol-binding protein concentrations. This study provides reference values for vitamin A concentrations at birth in very low birth weight neonates, which may be helpful in future studies designed to evaluate postnatal changes in the vitamin A status of these high-risk neonates.     

Energy expenditure, energy balance, and composition of weight gain in low birth weight infants fed diets of different protein and energy content

The effect of energy and protein intakes on energy expenditure, energy balance, and amount and relative rate of both protein and fat deposition in new tissue was investigated in 19 low birth weight infants whose mean protein and energy intakes, respectively, were 2.24 g/kg/d and 113 kcal/kg/d (formula A, n = 8), 3.6 g/kg/d and 115 kcal/kg/d (formula B, n = 5), and 3.5 g/kg/d and 149 kcal/kg/d (formula C, n = 6). The higher energy intake (formula C) but not the higher protein intake (formula B) resulted in greater energy expenditure. Both the higher protein (formula B vs formula A) and higher energy intakes (formula C vs formula B) resulted in greater weight gain secondary, in group B, to a greater absolute rate of protein deposition and, in group C, to a greater absolute rate of fat deposition. The relative composition of the new tissue deposited reflected the proportional intakes of protein and energy. The numerical value of the protein/fat ratio (g/g) of the new tissue deposited by infants fed formulas A and C, the protein contents of which were low relative to energy contents, were similar and significantly lower than the numerical value of the protein/fat ratio of the new tissue deposited by infants fed formula B, which had a higher protein content relative to energy content. These findings suggest that the composition of weight gain is related to both the absolute amounts and the proportions of dietary protein and energy; thus, both must be considered in formulation of nutritional regimens for LBW infants.     

Early predictors of mortality in very low birth weight neonates.

OBJECTIVE: To evaluate early predictors of mortality in very low birth weight neonates. SETTING: Teaching hospital. DESIGN: Case control study. METHODS: Hospital born very low birth weight newborns (500-1500 g) enrolled for study and followed up till death or 28 days. Infants' birth data and data on physiologic alterations, investigation and interventions in the first 24 hours of life and CRIB score were analyzed for their ability to predict neonatal mortality. RESULTS: 115 subjects were enrolled into the study of which 47 died in the neonatal period. The factors significantly associated with early neonatal mortality included birth weight, gestation, low Apgar scores, need for assisted ventilation at birth, need for supplemental oxygen and mechanical ventilation in the first 24 hours, presence of shock, hypoxia and acidosis (p < 0.05). The factors associated with late neonatal mortality were birth weight and gestation only. Multivariate analysis of these factors showed that besides low birth weight, shock, need for mechanical ventilation, acidosis and high alveolar-arterial oxygen gradients were significant predictors of neonatal mortality. When compared with the CRIB score, birth weight <1200g proved to be an equally good predictor of mortality risk. CONCLUSION: VLBW neonates with disturbed cardio-pulmonary physiology during the first 24 hours of life, especially those in need of mechanical ventilation, are at an increased risk of early neonatal mortality.     

Oral probiotics prevent necrotizing enterocolitis in very low birth weight neonates

OBJECTIVE: To test the hypothesis that normalizing the intestinal flora by administration of prophylactic probiotics would provide a natural defense, thereby reducing both the incidence and severity of necrotizing enterocolitis (NEC) in preterm neonates. STUDY DESIGN: Neonates < or =1500 g birth weight were randomized to either receive a daily feeding supplementation with a probiotic mixture (Bifidobacteria infantis, Streptococcus thermophilus, and Bifidobacteria bifidus; Solgar, Israel) of 10(9) colony forming units (CFU)/day or to not receive feed supplements. NEC was graded according to Bell's criteria. RESULTS: For 72 study and 73 control infants, respectively, birth weight (1152 +/- 262 g vs 1111 +/- 278 g), gestational age (30 +/- 3 weeks vs 29 +/- 4 weeks), and time to reach full feeds (14.6 +/- 8.7 days vs 17.5 +/- 13.6 days) were not different. The incidence of NEC was reduced in the study group (4% vs 16.4%; P=.03). NEC was less severe in the probiotic-supplemented infants (Bell's criteria 2.3 +/- 0.5 vs 1.3 +/- 0.5; P=.005). Three of 15 babies who developed NEC died, and all NEC-related deaths occurred in control infants. CONCLUSION: Probiotic supplementation reduced both the incidence and severity of NEC in our premature neonatal population.     

不同出生体重对新生儿静息能量消耗影响研究

为观察不同出生体重对新生儿静息能量消耗的影响,采用音接能量测定（DeltatracTM II,芬兰产）成功检测180例健康新生儿,其中男孩95例,女孩85例,按出生体重分成3组,即＜3000g组,3000g-3999g组,和≥4000g组,结果显示：体重＜3000g的新生儿能量消耗与体重在3000g-3999g之间的新生儿能量消耗无差异,而体重≥4000g的新生儿能量消耗与他们差异均有显著性,提示出生体重≥4000g的新生儿静息能量消耗明显低于体重在4000g以下的新生儿。