Measurements of bone turnover markers in premature infants

We determined the levels of circulating bone turnover markers in preterm infants during the first weeks of life. Twenty premature infants (mean gestational age 27+/-2.2 weeks, mean birth weight 894+/-231 g) hospitalized in the neonatal intensive care unit (NICU) at the Meir General Hospital, Israel, participated in the study. Measurements of bone turnover markers were performed at birth, and every week thereafter for an average follow-up of 11.2+/-0.7 weeks. Bone osteoblastic activity was assessed by measurements of circulating osteocalcin, bone-specific alkaline phosphatase (BSAP) and the C-terminal procollagen peptide (PICP) levels. Bone resorption was assessed by measurements of serum levels of the carboxy-terminal cross-links telopeptide of type I collagen (ICTP). All three markers of osteoblastic activity increased markedly and significantly during the first three weeks of life, and then continued to increase gradually until week 10 (p<0.01). Circulating ICTP levels increased in the first week of life and then decreased gradually throughout the follow-up (p<0.01). The study participants were divided into premature infants born at extremely low birth weight (ELBW: <1000 g, n=12) and very low birth weight (VLBW: 1000-1250 g, n=8). Osteocalcin (in weeks 2-5 of life), PICP (weeks 3-5), and ICTP levels (weeks 2-3) were significantly higher in VLBW preterms. These results suggest increased bone formation in premature infants in the first three months of life. The increased bone turnover in VLBW compared to ELBW premature infants may be the result of a generally higher morbidity in ELBW preterm infants in early stages of life.     

Effect of recombinant human erythropoietin on transfusion needs in preterm infants

OBJECTIVE: To study the efficacy, safety and cost effectiveness of recombinant human erythropoietin (r-HuEPO) in reducing erythrocyte transfusion needs in very low birthweight (VLBW) infants. METHODS: We conducted a non-blind randomized controlled trial and assigned 100 VLBW infants, less than 33 weeks gestation, to receive either r-HuEPO 750 U/kg per week subcutaneously from day 5 to day 40 or no erythropoietin (EPO). Infants received oral iron 3-6 mg/kg per day from day 10. Transfusion needs were analysed for all enrolled infants and in five weight subgroups: birthweight of less than 600 g, 600-799 g, 800-999 g, 1000-1199 g and infants more than 1200 g. RESULTS: VLBW infants on r-HuEPO attained higher reticulocyte counts and haematocrit than control infants but the mean number of transfusions and volume of erythrocyte transfused per infant were not statistically different. Of infants 800-999 g at birth, the mean number of transfusions per infant was 2.1 compared with 3.5 transfusions per control infant (P = 0.04). Volume of erythrocytes transfused was 34.9 +/- 32.1 mL/kg in r-HuEPO-treated infants and 56.6 +/- 25.8 mL/kg in control infants (P = 0.03). The cost per patient for transfusion and EPO was S$388 for r-HuEPO recipient and S$438 for control infant. Blood pressure, neutrophil count, platelet count and complications of prematurity were not significantly different in both groups of VLBW infants. CONCLUSION: r-HuEPO at 750 U/kg per week stimulates erythropoiesis in VLBW infants but significantly reduces the need for erythrocyte transfusion only in infants weighing 800-999 g at birth.     

Visual development in very low birth weight infants

Extremely preterm infants are at risk for neurodevelopmental problems and the visual system is particularly vulnerable. However, development of visual function in preterm infants with little or no retinal or neurologic injury has not been well defined. This study compared development of visual function in preterm infants without severe retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) to that of term infants at 5-7 mo corrected age. Twenty-one very low birth weight (VLBW) preterm infants (24-32 wk gestational age, weighing < 1500 g), and 22 healthy term infants were tested at 5-7 mo corrected age. Infants with any IVH/PVL and > Stage II ROP or Plus disease were excluded. Contrast sensitivity, grating acuity, and vernier acuity were measured using swept-parameter visual evoked potentials. Thresholds and maximum amplitudes were compared between groups. VLBW and term infants showed no differences in sensitivity for contrast (67.5 versus 63.8), grating resolution (12.4 versus 12.5 cpd) or vernier acuity (1.2 versus 1.0 arcmin). However, the amplitudes for swept contrast (p < 0.03) and swept vernier offset (p < 0.04) stimuli were higher in VLBW infants. Visual thresholds in VLBW infants without serious retinal or neurologic abnormalities were not significantly different from those of term infants, suggesting that increased visual experience does not influence visual sensitivity. The higher amplitudes in VLBW infants, suggests that visual experience may affect responses to suprathreshold stimuli.     

Impact of early dietary intake and blood lipid composition of long-chain polyunsaturated fatty acids on later visual development

BACKGROUND: In contrast to human milk, current infant formulas in the United States do not contain omega3 and omega6 long-chain polyunsaturated fatty acids. This may lead to suboptimal blood lipid fatty acid profiles and to a measurable diminution of visual function in developing term infants. The need for docosahexaenoic acid and arachidonic acid supplementation in the infant diet was evaluated in a double-blind, randomized clinical trial. METHODS: Healthy term infants were randomized to diets of (1) commercial formula, (2) docosahexaenoic acid-enriched formula (0.35% of total fatty acids), or (3) docosahexaenoic acid- (0.36%) and arachidonic acid- (0.72%) enriched formula. Eighty-seven infants completed the 17-week nutritional trial, and 58 were observed until 52 weeks of life. A reference group was exclusively breast fed for at least 17 weeks (n = 29). Outcome measures included electroretinographic responses, visual evoked potentials, and blood fatty acid analysis in infants at birth and at 6, 17, and 52 weeks of age. RESULTS: Commercial formula-fed infants had 30% to 50% lower content of docosahexaenoic acid in total red blood cell lipids during the 17-week feeding trial compared with breastfed infants. Significant differences persisted at the 1-year follow-up. Arachidonic acid content was consistently reduced in the commercial formula group by 15% to 20%. Infants fed long-chain polyunsaturated fatty acid-enriched formulas had docosahexaenoic acid and arachidonic acid blood lipid profiles resembling those of human milk-fed infants. Infants receiving this enriched formula had more mature electroretinographic responses than commercial formula-fed infants at 6 weeks of age. Human milk-fed and docosahexaenoic acid-enriched formula-fed infants had better visual acuity than commercial formula-fed infants at both 17 and 52 weeks of age. Early (17-week) fatty acid profiles in blood lipids were correlated with later (52-week) visual function development in study infants. CONCLUSIONS: Results from this clinical trial demonstrate that long-chain polyunsaturated fatty acid supplementation of formula in term infants produces blood lipid fatty acid profiles that are similar to those observed in breast-fed infants. This supplementation leads to better visual function later in life (i.e., 1 year of age) than that shown by infants fed commercial formula.     

Bone mineralization outcomes in human milk-fed preterm infants.

We evaluated bone mineralization by single photon absorptiometry at 2 y in a cohort of preterm infants studied since birth. Infants were fed human milk fortified with Ca [to achieve 80 mg/dL (19.96 mmol/L)] and P [40 mg/dL (12.91 mmol/L)] from wk 2 through 8 after birth. After hospital discharge, infants were divided into two groups (HM and F) determined by the timing of the introduction of cow milk-based formula. Mid-radius bone mineral content (BMC) was assessed in 10 infants who were breast-fed (HM) for a minimum of 2 mo after hospital discharge and 11 who were bottle-fed (F). The mean duration of human milk-feeding differed by design between HM and F groups (31 +/- 15 versus 11 +/- 3 wk, respectively). Although we had observed previously that group F had significantly greater BMC values at 16, 25, and 52 wk compared with values in group HM, we found similarities in BMC values (180 +/- 30 mg/cm) between groups at 2 y. The 2-y cohort comprised healthy infants and the groups had similar birth weights, lengths of gestation, and values for weight (10.8 +/- 1.1 kg), length (82 +/- 2 cm), and bone width (7.8 +/- 1.1 mm). Follow-up outcomes at 2 y in preterm infants fed fortified human milk in hospital suggest that if they continue to receive human milk after hospital discharge, radius BMC will "catch-up" to that of similar infants given formula in the posthospitalization period.     

Growth and neurodevelopmental outcome of VLBW infants at 1 year corrected age

Objectives

To evaluate growth and neurodevelopmental outcome of very low birth weight infants (VLBW) and compare with term normal birth weight infants (NBW) till 12 months corrected age.

Design

A prospective cohort study

Setting

Tertiary care neonatal unit in northern India

Subjects

37 VLBW infants and 35 NBW infants born between January 2007 and December 2007.

Interventions

Anthropometric measurements were recorded and Z-scores were computed serially at birth, discharge, 40 weeks post menstrual age (PMA), and at 1, 3, 6 and 12 months of corrected age. Developmental quotient (DQ) at 12 months corrected age was assessed.

Results

Z-scores for weight, length and head circumference (HC) at birth were ?1.21(±0.92), ?0.98(±1.32) and ?0.70(±1.14), respectively for VLBW infants and ?0.37(±0.72), ?0.11(±0.96) and 0.05(±0.73) respectively for NBW infants. VLBW infants had a significant drop in all Z-scores by discharge (P<0.001). There was a catch up to birth scores by 12 month age. VLBW infants had significantly lower Z-scores for weight, length and HC at one year corrected age as compared to NBW infants (P =0.01, 0.04 and 0.001, respectively). DQ at 12 months was significantly lower in VLBW infants (91.5+7.8) than NBW infants (97.5±5.3) (P <0.001). DQ of small for gestational age (SGA) and appropriate for gestational age (AGA) VLBW infants was comparable.

Conclusion

VLBW infants falter in their growth during NICU stay with a catch-up later during infancy. In comparison to NBW infants, they continue to lag in their physical growth and neurodevelopment at 1 year of corrected age.     

Plasma gastrin and somatostatin levels in newborn infants receiving supplementary formula feeding

Plasma gastrin and somatostatin concentrations were measured by radioimmunoassay in exclusively formula-fed infants and in breast-fed infants receiving supplementary formula during the first five postnatal days. Infants exclusively formula fed had a progressive increase in mean plasma gastrin concentration from 109±42 pmol/l (mean±SD) on the first day to 236±103 pmol/l on the fifth day after birth ( p = 0.0001). Breast-fed infants receiving supplementary formula had similar hormone concentrations as formula-fed infants of corresponding postnatal age and they also had a significant increase in hormone levels from the first to the fifth day ( p = 0.0001). A positive relationship was found between gastrin concentration and ingested milk volume: Rs = 0.51, n = 105, p = 0.0001. The high gastrin concentrations most probably reflect enhanced hormonal release from the gastrin-producing cells in response to increasing volumes of milk ingested by the infant. The mean plasma somatostatin concentration on the first day after birth was 18 ± 6 pmol/l. No significant change occurred during the first five postnatal days, independent of feeding type.     

Multicenter study to assess safety and efficacy of INH-A21, a donor-selected human staphylococcal immunoglobulin, for prevention of nosocomial infections in very low birth weight infants

BACKGROUND: Prophylactic administration of intravenous immunoglobulin has been inconsistent in reducing the risk of sepsis in very low birth weight (VLBW) infants presumably because of varying titers of organism specific IgG antibodies. INH-A21 is an intravenous immunoglobulin from donors with high titers of antistaphylococcal antibodies. This dose-ranging study explored safety and preliminary activity of INH-A21 for prevention of staphylococcal sepsis in VLBW infants. METHODS: This was a multicenter, double blind, group-sequential study. Infants with birth weights 500-1250 g were randomized to receive up to 4 doses of placebo, 250 mg/kg, 500 mg/kg or 750 mg/kg INH-A21. Safety and frequencies of sepsis were compared across treatment groups. RESULTS: All treatment groups had similar mean gestational age, birth weight, Apgar score and maternal use of antibiotics. Randomizations to 250 mg/kg (N = 94) and 500 mg/kg (N = 96) doses were terminated after interim analyses demonstrated a low probability of finding a difference when compared with placebo. Infants randomized to the INH-A21 750 mg/kg group (N = 157) had fewer episodes of Staphylococcus aureus sepsis [relative risk (RR), 0.37; 95% confidence interval (CI), 0.12-1.12; P = 0.14], candidemia (RR 0.34; 95% CI 0.09-1.22; P = 0.09) and mortality (RR 0.64; 95% CI 0.25-1.61; P = 0.27) when compared with the placebo-treated cohort (N = 158). No dose-related trends were observed for adverse events or morbidities associated with prematurity. CONCLUSIONS: INH-A21 750 mg/kg demonstrated potential to reduce sepsis caused by S. aureus, candidemia and mortality in VLBW infants. Although statistical significance was not reached, based on the magnitude of the estimated differences, the efficacy and safety of INH-A21 750 mg/kg should be evaluated in an adequately powered, well-controlled study.     

Does type of feeding affect body composition in very low birth weight infants? – A prospective cohort study

Background

The aim of the study was to analyse body composition of preterm infants fed with either breast milk or formula compared to a control group of full-term newborns.

Variables affecting apolipoprotein B measurements in 3- to 5-day-old babies: a study of 4491 neonates

To investigate the feasibility of establishing a neonatal screening program for familial type II hypercholesterolemia, we assayed apolipoprotein B (Apo B), using a radial immunodiffusion assay, in dried blood spot samples from 4491 consecutively born, 3- to 5-day-old neonates. We explored factors influencing levels at the time of sampling and factors associated with the handling of the dried blood spot samples before assay which could affect the assayed value. Assayed Apo B levels were distributed continuously and decreased with increasing delay and temperature of storage of the samples before assay. Female neonates had significantly higher mean Apo B levels than males (p less than 0.0001), with their respective means +/- SD being 0.246 +/- 0.085 g/liter (n = 2086) and 0.225 +/- 0.079 g/liter of whole blood (n = 2390). In both sexes mean Apo B levels were significantly lower in low birth weight (less than or equal to 2.5 kg) and in low gestational age (less than or equal to 36 wk) neonates. For neonates with birth weight greater than 2.5 kg and gestational age more than 36 wk, Apo B levels increased with increasing birth weight and gestational age. Sex, birth weight, and gestational age could account for 5.7% of the variability of Apo B. After adjustments for these variables, the neonate's age at sampling did not influence Apo B levels significantly. Apo B levels were not affected by different dietary regimens, whether breast-fed, formula-fed, or breast-fed with formula complement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Physical growth and retinopathy in preterm infants: involvement of IGF-I and GH.

GH and IGF-I are important for physical growth. We measured serum levels of these factors in preterm infants. The study population (n = 81) was divided into three groups according to the gestational age. We evaluated differences in serum GH and IGF-I levels among groups with regard to physical growth and development of retinopathy of prematurity. Serum GH levels in extremely preterm infants born at <28 wk of gestational age were significantly higher than levels in those born between 28 and 34 wk at 1 and 2 mo of age. In contrast, serum IGF-I levels in extremely preterm infants remained low, whereas those in the other two groups gradually increased. Evaluation of the effects of GH and IGF-I on physical growth in very low birth weight infants (<1500 g) showed that IGF-I concentrations were positively related to physical growth for several months after birth, whereas no relationship was observed between GH and physical growth. Multivariate analysis demonstrated that high GH concentration at 1 mo of age was significantly associated with development of severe retinopathy of prematurity. In conclusion, persistent low serum IGF-I levels may explain the slow physical growth during neonatal life, and exposure of high GH may cause, at least in part, severe retinopathy of prematurity in preterm infants.     

Plasma amino acid differences in very low birth weight infants fed either human milk or whey-dominant cow milk formula

Midmorning plasma amino acid levels were measured in 31 healthy, very low birth weight infants (mean age 16 days, mean birth weight 1180 g, gestation 29 wk) during 96-h balance studies. All infants received continuous enteral infusion of isonitrogenous, isocaloric preparations of either human milk fortified with pasteurized, lyophilized fractions of mature human milk (n = 18) or whey-dominant cow milk-based formula (n = 13). Weight gain (15 g/kg/day), nitrogen retention (303 mg/kg/day), and metabolizable energy (104 kcal/kg/day) were similar between groups. Plasma levels of threonine, valine, and the sum of essential amino acids were significantly greater in the whey-dominant formula-fed infants (p less than 0.01). Taurine and cystine were measured in significantly greater concentrations in the fortified human milk and threonine, valine, methionine, and lysine in the whey-dominant cow milk formula (p less than 0.01). Relationships between plasma amino acid levels and indices of nitrogen utilization differed between groups. These differences suggest that further modifications of whey-dominant formulas may be indicated.     

Serum growth hormone-binding proteins in the human fetus and infant.

Growth hormone-binding protein (GH-BP) levels were studied in cord serum of 69 human infants born after 24 to 41 wk of gestation and in serum of 14 infants aged 1 to 3 mo. GH-BP levels were measured by HPLC-gel filtration of serum incubated overnight with 125I-hGH. The radioactive elution profile revealed two small 125I-hGH peaks of high molecular weight and a large peak, corresponding to monomeric 125I-hGH. The first peak of high molecular weight was variable, showed some of the characteristics (high molecular weight, displaceability by a large excess of unlabeled hGH) of the described low affinity, high capacity GH-BP, and did not correlate with gestational age or birth weight (peak I-BP). The second peak was identified as 125I-hGH bound to the high affinity, low capacity GH-BP (peak II-BP). Mean +/- SD specific binding of 125I-hGH to this peak was significantly (p less than 0.0001) different between preterm infants (3.1 +/- 1.1%; n = 51), term infants at birth (4.2 +/ 1.1%; n = 18), and 1- to 3-mo-old infants (8.5 +/- 1.6%; n = 14). To evaluate the effect of intrauterine nutritional state, the ponderal index (weight/lengths) was calculated. Peak II-BP levels were lower (p less than 0.05) in infants with the ponderal index less than 2.35 (2.8 +/- 1.0%; n = 20) than in those with the ponderal index between 2.35 and 2.65 (3.4 +/- 1.2%; n = 29) or greater than 2.65 (3.8 +/- 1.2%; n = 20).(ABSTRACT TRUNCATED AT 250 WORDS)     

Deletion allele of angiotensin-converting enzyme is associated with increased risk and severity of bronchopulmonary dysplasia

OBJECTIVE: To explore whether the deletion (D) allele of angiotensin-converting enzyme (ACE) is associated with the risk or severity of bronchopulmonary dysplasia (BPD) among very low birth weight (BW) infants. STUDY DESIGN: Infants with a BW < or = 1250 g were prospectively recruited. The D and I (insertion) alleles of ACE were determined using a polymerase chain reaction followed by restriction fragment length polymorphism analysis. RESULTS: Infants with DD/DI genotype of ACE had a (mean +/- SD) birth weight (938 +/- 204 g vs 925 +/- 196 g) and gestational age (28 +/- 3 weeks vs 28 +/- 2 weeks), similar to infants with II genotype of ACE (P > .05). Infants with DD/DI genotype of ACE were more likely to have BPD than infants with II genotype (47% vs 22%, P = .025). Among infants with BPD, ACE DD/DI genotype was more common among infants with moderate or severe BPD compared with infants with mild BPD (74% vs 26%, P = .012). The number of D alleles of ACE correlated directly and positively with the severity of BPD (R = 0.23, P = .045). CONCLUSION: The D allele of ACE is associated with an increased risk and severity of BPD among preterm infants.     

Continuous gastric pH measurement in young and older healthy preterm infants receiving formula and clear liquid feedings

Gastric pH was recorded with an intragastric pH electrode for 12 h in two groups of healthy, preterm infants with similar birth weights (range 1.4 to 2.0 kg). Group I infants (n = 13) were less than 7 days old and Group II infants (n = 10) were 7-15 days old. Infants were fed three formula feedings and one clear liquid feeding during the study. In Group I, mean gastric pH measured at 15-min intervals was above 4.0 for 3 h after either feeding. In Group II mean gastric pH was lower particularly after clear liquid feedings, where it remained below pH 4.0 for the entire 3-h postprandial period. The percent of monitored time at gastric pH less than 4.0 was low in Group I--15.2 +/- 4.2% and 20.6 +/- 6.4% after formula and clear liquid, respectively. The percent time was greater in Group II--42.7 +/- 8.0% and 61.9 +/- 7.3% after formula and clear liquid, respectively. In the younger preterm infant, gastric pH does not appear sufficiently low to support peptic activity.     

Immune status of infants fed soy-based formulas with or without added nucleotides for 1 year: part 2: immune cell populations

BACKGROUND: Infants fed a soy protein isolate-based formula have immunization responses similar to breast-fed infants. However, cellular aspects of the immunologic development of soy-fed infants have not been studied extensively. Nucleotides added to milk-based formula benefit infant immune status, but reports of the immunologic effects of adding nucleotides to soy-based formula are not available. This study examines immune cell populations of infants fed soy protein isolate formulas with and without added nucleotides for 1 year. METHODS: Newborn, term infants studied in a masked 12-month feeding trial were assigned randomly to soy formula groups with and without added nucleotides (n = 94, n = 92). A nonrandomized human milk/formula-fed cohort (n = 81), was concurrently enrolled. Blood samples were collected at 6, 7, and 12 months. Thirty-two immune cell populations were characterized using three-color flow cytometry. Cellular markers were chosen to assess general pediatric immune status, emphasizing maturation and activation of B, T, and NK lymphocytes. RESULTS: All cell populations, number and percentages, were within age-related normal ranges. The only significant difference found between soy formula and human milk/formula-fed infants was the percentage of CD57 + NK T cells at 12 months (human milk/formula > soy formula, P = 0.034). There were significant differences at some time points between human milk/formula-fed and nucleotide-supplemented soy formula-fed infants in populations of lymphocytes, eosinophils, total T, helper T, naive helper, memory/effector helper, CD57 - T, and CD11b + CD8 + NK cells. None of the cell populations differed between infants fed soy formula versus soy plus nucleotides. CONCLUSIONS: Infants fed this commercial soy formula demonstrated immune cell status similar to human milk/formula-fed infants, consistent with normal immune system development. The addition of nucleotides to soy formula did not significantly change specific individual immune cell populations but tended to increase numbers and percentages of T cells and decreased numbers and percentages of NK cells.     

Abnormalities in zinc homeostasis in young infants with cystic fibrosis

Low plasma zinc concentrations have been reported in approximately 30% of young infants with cystic fibrosis identified by newborn screening. The objective of this study was to examine zinc homeostasis in this population by application of stable isotope methodology. Fifteen infants with cystic fibrosis (9 male, 6 female; 7 breast-fed, 8 formula-fed) were studied at a mean (+/-SD) age of 1.8 +/- 0.7 mo. On d 1, 70Zn was administered intravenously, and 67Zn was quantitatively administered with all human milk/formula feeds during the day. Three days later, a 3-d metabolic period was initiated, during which time intake was measured and complete urine and fecal collections were obtained. Fractional zinc absorption, total absorbed zinc, endogenous fecal zinc, and net absorbed zinc were measured; fecal fat excretion was also determined. Fractional absorption was significantly higher for the breast-fed infants (0.40 +/- 0.21) compared with the formula-fed group (0.13 +/- 0.06) (p = 0.01), but with the significantly higher dietary zinc intake of the formula-fed group, total absorbed zinc was higher for those receiving formula (p = 0.01). In 1 infants with complete zinc metabolic data, excretion of endogenous zinc was twofold greater for the formula-fed infants (p < 0.05); net absorption (mg zinc/d) was negative for both feeding groups: -0.04 +/- 0.52 for breast-fed; -0.28 +/- 0.57 for formula-fed. Endogenous fecal zinc losses correlated with fecal fat excretion (r = 0.89, n = 9, p = 0.001), suggesting interference with normal conservation of endogenously secreted zinc. These findings indicate impaired zinc homeostasis in this population and suggest an explanation for the observations of suboptimal zinc status in many young infants with cystic fibrosis prior to diagnosis and treatment.     

Esophageal atresia in infants with very low birth weight

Infants with esophageal atresia (EA), with or without a tracheoesophageal fistula (TEF) frequently are of low birth weight. With advances in neonatal, respiratory, surgical, and anesthetic care, more infants with very low birth weight (VLBW; birth weight less than 1.5 kg) are surviving. The therapy of the VLBW neonate with EA is not longer automatically staged. Primary or delayed primary anastomosis can be performed safely if the patient is stable. This report will review the epidemiology, pathophysiology, treatment, and prognosis of EA in VLBW infants. The authors present their own experience in dealing with the VLBW with EA and review the world literature.     

极/超低出生体重儿生后早期腹部局部组织氧饱和度变化趋势的前瞻性研究

目的 探讨极/超低出生体重儿（very/extremely low birth weight infant,VLBWI/ELBWI）出生后的腹部局部组织氧饱和度（abdominal regional oxygen saturation,A-rSO₂）变化趋势。 方法 选取2019年9月至2021年5月在新生儿重症监护室住院的VLBWI/ELBWI作为研究对象。利用近红外光谱技术,从出生后第1天开始每天监测A-rSO₂,共监测4周。并根据出生胎龄分为较低胎龄组（<29周组）及较高胎龄组（≥29周组）,对两组VLBWI/ELBWI生后4周内的A-rSO₂进行比较分析。 结果 共纳入VLBWI/ELBWI 63例,其中<29周组30例,≥29周组33例。63例VLBWI/ELBWI生后2周内A-rSO₂呈现波动变化：生后第1天为最低值（47.9%）,后逐渐升高,第4天达最高峰（67.4%）,第5~9天逐渐下降,然后再次上升,至出生2周后趋于稳定。≥29周组出生后第1周及第2周A-rSO2均高于<29周组,差异有统计学意义（P<0.05）。出生第3周及第4周两组A-rSO₂均值比较差异无统计学意义（P>0.05）。 结论 VLBWI/ELBWI的A-rSO₂在出生后最初2周随日龄增加存在波动变化,2周后趋于稳定;生后2周内的A-rSO₂与胎龄相关。     

Role of plasma and urinary calcium and phosphorus measurements in early detection of phosphorus deficiency in very low birthweight infants

Aim: To analyse the role of serum and urinary calcium and phosphorus levels in early detection of mineral deficiency in very low birthweight (VLBW) infants born appropriate (AGA) and small for gestational age (SGA). Methods: 64 VLBW infants were included in a cohort study and divided into two groups: AGA (n = 30) and SGA infants (n = 34). Then, they were divided according to the presence of radiological signs of metabolic bone disease (MBD): with MBD (n = 21) and without MBD (n = 34). Blood samples and 6 h urine collections were obtained for calcium, phosphorus, alkaline phosphatase activity and creatinine determinations between 3 and 5 wk of life. Results: There were no biochemical differences between AGA and SGA. Higher values of urinary calcium (MBD = 31.9 3 20.2, without MBD = 19.8 3 15.4; p = 0.017), calciuria (MBD = 2.3 3 0.3, without MBD = 1.4 3 0.8; p = 0.037) and alkaline phosphatase activity (MBD = 369 3 114, without MBD = 310 3 93; p = 0.04) were found in infants who developed MBD. Both groups showed high tubular phosphorus reabsorption indicating mineral deficiency. Conclusion: Serum calcium and phosphorus levels are not good markers in early detection of mineral deficiency. However, the monitoring of calcium urinary levels may be helpful in early detection of mineral deficiency.