早产儿临床流行病学研究现状

早产是当今新生儿学及围生医学研究的核心问题,近年来,早产儿发生率呈上升趋势.虽然随着现代医疗技术水平的提高,早产儿存活率亦有所提高,但众多并发症使其预后状况不佳.早产儿临床流行病学研究对临床医生提高早产儿诊疗水平有指导性意义,该文就早产发生原因、主要并发症及预防等方面的临床流行病学研究进展进行综述.     

Total energy expenditure, body composition and weight gain in moderately preterm and full-term infants at term postconceptional age

AIM: To assess total energy expenditure (TEE) and body composition, i.e. total body water (TBW) and adipose tissue volume (ATV), at term age in 8 healthy preterm infants, born between gestational weeks 30 and 33, and in 9 healthy full-term newborns. METHODS: Total and subcutaneous ATVs were assessed using magnetic resonance imaging, while TEE and TBW were estimated using doubly labelled water. RESULTS: Total ATV was 272 +/- 21 and 261 +/- 56 ml/kg body weight, while subcutaneous ATV was 88.9 +/- 1.6 and 89.7 +/- 2.0% of total ATV for preterm and full-term infants, respectively. The corresponding figures for TBW (as percentage of body weight) were 67.4 +/- 2.5 and 68.1 +/- 4.1, respectively. A significant correlation between ATV/kg body weight and body weight was found for full-term (p < 0.0001) but not for preterm infants. TEE for preterm infants was 315 +/- 20 kJ/kg body weight/24 h, which was significantly higher (p < 0.05) than TEE for full-term infants (254 +/- 45 kJ/kg body weight/24 h). At the time of investigation preterm infants weighed significantly (p < 0.05) less (540 g) than full-term infants. After the time of investigation, weight gains of preterm and full-term infants were 38 +/- 12 and 24 +/- 14 g/24 h, respectively. CONCLUSION: When compared to full-term newborns, predominantly breastfed healthy preterm infants at term postconceptional age were significantly smaller, had a similar average proportion of body fat and showed catch-up growth. Their higher TEE/kg body weight can be explained by a higher growth rate and possibly also by higher physical activity.     

The effect of a fructo-oligosaccharide supplemented formula on gut flora of preterm infants

AIM: The intestinal flora of breast-fed infants is generally dominated by bifidobacteria which have beneficial properties. Their presence is due to various components of breast milk, including prebiotic substances. This prospective double-blind study compared the numbers of bifidobacteria in the stool flora of bottle-fed preterm infants randomized to receive for 14 days either a formula with prebiotic fructo-oligosaccharides at a concentration of 0.4 g/dL or the same formula with maltodextrin as a placebo. METHODS: Within 0-14 days after birth, 56 healthy bottle-fed infants were enrolled to receive either the prebiotic or placebo. Faecal samples were taken at inclusion day and at study day 7. The number of bifidobacteria in the stools, stool characteristics and somatic growth were recorded during the study. RESULTS: In the group fed fructo-oligosaccharides, both the numbers of bifidobacteria in the stools and the proportion of infants colonized with them were significantly higher as compared to the placebo group (p=0.032 and p=0.030 respectively). There was also a higher number of bacteroids in the fructo-oligosaccharide group as compared to the placebo (p=0.029). At the same time, reduction was noted in the numbers of Escherichia coli and enterococci. (p=0.029, and p=0.025, respectively). Supplementation had also significant influence on stool frequency per day (p=0.0080). CONCLUSION: An infant formula containing a small quantity of prebiotic oligosaccharides is well accepted and leads to rapid growth of bifidobacteria in the gut of bottle-fed preterm infants while decreasing the numbers of pathogenic microorganisms.     

早产儿早期应用静脉营养的研究进展

早产儿的营养问题是近年来新生儿科极为关注的问题.对于三大物质(葡萄糖、蛋白质及脂肪)的代谢及利用,早产儿有其自身的特点.经典的静脉营养方案为了避免其对早产儿产生的不良反应,都是循序渐进地给予脂肪乳及氨基酸,但易使早产儿处于营养缺乏状态.近几年的临床研究表明,生后24h内即给予早产儿足量的静脉营养液不仅为早产儿的生长发育...     

Optimal protein and energy intakes in preterm infants

There is compelling evidence that current nutritional practice fails to provide sufficient dietary protein for preterm infants, especially extremely and very low birth weight infants. Nutrient requirements can be estimated by a variety of techniques, but most suggest that these infants will require a protein intake of 3.5-4.0 g/kg/d. Even when these infants are able to tolerate full enteral feeds, most currently available artificial milk formula or breast milk fortifiers will not ensure these protein requirements are met except when fed at high volumes. Energy requirements on the other hand may be currently met, and evidence from controlled studies suggests that intakes higher than 110-135 kcal/kg/d might not be beneficial. The data from studies on neonatal adiposity outcomes, and from studies examining relationship between early growth and later cardiovascular outcome, also suggest that excess nutrient intake might be harmful. In the light of this data, optimal intakes and protein-energy ratios require re-appraisal.     

Hepatitis B vaccination in preterm infants

Preterm infants, especially those with very low birth weight, are at risk of hepatitis B virus infection. They often require invasive diagnostic methods in their first weeks of life, intensive treatment and long-term hospitalisation. Therefore, hepatitis B vaccination is particularly justified in these patients. Our aim was to determine the reaction of preterm children to hepatitis B vaccination. The study comprised 64 preterm children whose birth weight ranged from 700 g to 2460 g (mean 1776.6 g ± 480.4 g) and whose gestational age was between 25 and 36 weeks. A 10 μg dose of the recombinant vaccine Engerix-B (SmithKline Beecham) was given at intervals of 0, 1, 2 and 12 months. In 49.2% of the children vaccination was administered on the 1st day of life, and in the remaining cases between the 2nd and 119th days post delivery. One month after vaccination completion the levels of anti-hepatitis B surface antigen (HBs) antibodies were evaluated. In 98.4% of the vaccinated preterm infants the level of antibodies was >10 mIU/ml. Mean level of anti-HBs antibodies in the group of children with birth weight ≤ 2000 g was 2431.4 mIU/ml, while in those with birth weight >2000 g it was 4803.9 mIU/ml. In children with a birth weight ≤ 1000 g, the mean level of anti-HBs antibodies was significantly lower than in those with birth weight >2000 g. The level of anti-HBs antibodies in children who started vaccination >1st day of life was significantly lower in preterm children with a birth weight ≤ 2000 g than in those with a birth weight >2000 g. Although vaccination was started on the 1st day of his life, one child with birth weight of 2300 g developed a hepatitis B virus infection. One child did not respond to vaccination (anti-HBs < 10 mIU/ml) and in three cases the response was very poor (11–100 mIU/ml). These patients were given a supplementary booster double dose of Engerix B (20 μg). After 1 month the level of anti-HBs antibodies was evaluated again and high values of 657 mIU/ml to 14520 mIU/ml were observed. In the group of children with a birth weight ≤ 1000 g the response to vaccination was weaker as compared to children with a birth weight >2000 g (P < 0.05). In systematic mass vaccination programmes, monitoring of antibody levels is not recommended unless the patient is at risk. However, in extremely preterm infants (< 1000 g at birth), especially after very serious infections, monitoring the level of anti-HBs antibodies after complete immunisation should be considered. In preterm infants who show very low post-vaccination levels of anti-HBs antibodies, stimulation with an additional double booster dose of vaccine gives positive results. Conclusion The majority of preterm infants (98.4%) responded well to hepatitis B vaccination given at intervals of 0, 1, 2 and 12 months and developed a protective level of antibodies. The level of anti-hepatitis B surface antigen antibodies in children with a birth weight >2000 g was higher than in those with a birth weight ≤ 1000 g. Received: 24 February 1998 / Accepted in revised form: 29 September 1998     

早产儿支气管肺发育不良的防治

随着围生医学的发展,早产儿存活率上升,支气管肺发育不良(bronchopulmonary dysplasia,BPD)发病率也逐年增高.BPD是一种由多因素引发的慢性肺疾病,其病因及发病机制复杂,早期病死率高,晚期伴有呼吸系统,甚至神经系统的不良结局,严重影响早产儿存活率及生活质量.该文就BPD的防治进展作一综述.     

早产儿喂养不耐受的诊治进展

虽然早产儿喂养不耐受的定义及诊断在不断地修改与完善,但迄今为止,仍缺乏统一的定义及诊断标准.有关其干预措施(包括喂养策略、母乳喂养、药物治疗等)的疗效,尚需要大量的临床随机研究去验证和评估.该文将对喂养不耐受定义、喂养策略,药物治疗等进展进行综述.     

早产儿脑室周围白质软化的多因素分析

目的　探讨早产儿脑室周围白质软化 (PVL)的高危因素。方法　对合并PVL与未合并PVL的早产儿(各 2 6例 )进行病例对照研究 ,对 18种危险因素进行Logistic回归分析。结果　胎膜早破 (PROM )、生后 4h内的pH值、动脉氧分压、生后 3d内最低二氧化碳分压、生后第 1周超声发现脑室周围强回声团 (PVE)的OR值分别为 2 383、3 2 77、3 76 9、3 96 5、1 931(P <0 0 1)。建立的早产儿PVL主效应模型为Logit(P) =β0 +0 897PROM - 1 346PaO2 - 1 2 78pH - 1 4 6 7PaCO2 +0 792PVE(χ2 =2 1 378,P =0 0 0 1)。结论　PROM、低氧血症、酸中毒、低碳酸血症、PVE为早产儿PVL的高危因素。     

Altered body composition in preterm infants at hospital discharge

Aim:  To test the hypotheses that body size is reduced and body composition altered in preterm infants at hospital discharge.
Methods:  Preterm infants (≤34 weeks gestation, ≤1750 g at birth) were enrolled. Body weight, length and head circumference were converted to standard deviation or z- scores. Body composition was measured using dual emission X-ray absorptiometry. The results were analysed using standard statistics.
Results:  One hundred and forty-nine infants (birth weight = 1406 ± 248 g, gestation = 31 ± 1.7 weeks) were studied. Postmenstrual age at discharge was 37 ± 1.2 weeks. Z -scores for head circumference, weight and length differed (−0.1 ± 0.6 > −1.4 ± 0.6 > −1.9 ± 0.6; p < 0.0001). Global fat-free mass was less in study infants than the reference infant at the same weight (2062 < 2252 g; p < 0.0001) or gestation (2062 < 2667 g; p < 0.0001). Global fat mass was greater in study infants than the reference infant at the same weight (307 > 198 g, 13 > 8%) or gestation (307 > 273 g; 13 > 9%; p < 0.0001). Changes in central fat mass closely paralleled those in global fat mass (r² = 0.76, p < 0.0001).
Conclusion:  Reduced linear growth and a reduced fat-free mass suggest that dietary protein needs were not met before discharge. A reduced fat-free mass coupled with an increased global and central fat mass echoes concerns about the development of insulin resistance and metabolic syndrome X in these high-risk infants.     

The effect of postnatal age on the early tactile manual abilities of preterm infants

Background

Although preterm infants possess early tactile manual abilities, the influence of the postnatal experience has not yet been systematically examined.

Aims

To investigate whether early tactile manual habituation, discrimination and recognition (following interference) of shape in preterm infants are modified by postnatal age.

Study design

Prospective study.

Subjects

Forty preterm infants were assessed from the post-conceptional age (PCA) of 34 weeks. Two groups were made up according to postnatal age (PNA): low PNA (PNA ≤ 10 days of life) and high PNA (PNA ≥ 12 days of life).

Outcome measures

An object (prism or cylinder) was presented repeatedly in the left hand, and holding times of the object were recorded during each trial.

Results

Holding time was shorter for all preterm infants following successive presentation of the same object irrespective of postnatal age range. In the discrimination phase, the mean holding time for the novel object was longer than holding times in the last two habituation trials, in both PNA groups. Finally, the mean holding time of the familiar object presented in the recognition phase was shorter than the holding time of the novel object presented previously, but only in the low PNA group.

Conclusions

Tactile manual habituation and discrimination of shape information is present in preterm infants at a post-conceptional age of 34 weeks, independently of postnatal age. However, tactile manual recognition of familiar shapes following interference is affected by length of postnatal experience. The significance of this last result is discussed in detail.     

Effects of pre-feeding oral stimulation on oral feeding in preterm infants: A randomized clinical trial

Objective

To evaluate the effect of early oral stimulation before the introduction of oral feeding, over the duration of concomitant tube feeding (“transition period”), the length of hospital stay and the breastfeeding rates upon discharge in preterm infants.

Study design

Preterm infants born between 26 and 33 weeks gestational age (n = 86), were randomized into an intervention and control group. Infants in the intervention group received an oral stimulation program consisting in stimulation of the oral structures for 15 min at least for 10 days, before introduction of oral feeding. Oral feeding was introduced at 34 weeks GA in both groups.

Results

Breastfeeding rates upon discharge were significantly higher in the intervention than in the control group (70% versus 45.6%, p = 0.02). There was no statistical difference between the two groups in terms of the length of the transition period or the length of the hospital stay.The need for prolonged CPAP support (HR = 0.937, p = 0.030) and small size for gestational age at birth (HR = 0.338, p = 0.016) were shown to be risk factors for a prolonged transition period.

Conclusion

A pre-feeding oral stimulation program improves breastfeeding rates in preterm infants. The study results suggest that oral stimulation, as used in our specific population, does not shorten the transition period to full oral feeding neither the length of hospital stay.     

The effect of neutral and acidic oligosaccharides on stool viscosity, stool frequency and stool pH in preterm infants

Aim: To determine the effect of neutral oligosaccharides [small‐chain galacto‐oligosaccharides/long‐chain fructo‐oligosaccharides (scGOS/lcFOS)] in combination with acidic oligosaccharides (pAOS) on stool viscosity, stool frequency and stool pH in preterm infants. Methods: In this explorative RCT, preterm infants with gestational age <32 weeks and/or birth weight <1500 g received enteral supplementation with scGOS/lcFOS/pAOS or placebo (maltodextrin) between days 3 and 30 of life. Stool samples were collected at day 30 after birth. Results: In total, 113 infants were included. Baseline and nutritional characteristics were not different between both groups. Stool viscosity at day 30 was lower in the prebiotics group (16.8N) (3.9–67.8) compared with the placebo group (26.3N) (1.3–148.0) (p = 0.03; 95% CI ?0.80 to 0.03). There was a trend towards higher stool frequency in the prebiotics group (3.1 ± 0.8) compared with the placebo group (2.8 ± 0.7) (p = 0.15; 95% CI ?0.08 to 0.52). Stool pH at day 30 was lower in the in the prebiotics group (5.9 ± 0.6) compared with the placebo group (6.2 ± 0.3) (p = 0.009; 95% CI 0.08 to 0.53). Conclusions: Enteral supplementation of a prebiotic mixture consisting of neutral (scGOS/lcFOS) and acidic oligosaccharides (pAOS) decreases stool viscosity and stool pH with a trend towards increased stool frequency in preterm infants. The inclusion of pAOS in a formula containing a mixture of scGOS/lcFOS does not add specific advantages to the formula in terms of stool viscosity, frequency, pH as well as feeding tolerance.     

Acid oro-pharyngeal secretions can predict gastro-oesophageal reflux in preterm infants

Acid gastro-oesophageal reflux (GOR) is common in preterm infants but there is a lack of a non-invasive technique to establish the diagnosis. The aim of this study was to identify whether the presence of acid in oro-pharyngeal secretions (OPS) was a valid indicator of clinically significant acid GOR in preterm infants. A total of 23 infants with suspected GOR were studied with 24 h lower-oesophageal pH monitoring and during this period the OPS were tested for acid with litmus paper at 6 hourly intervals. Median (range) gestation was 28 weeks (24–31), birth weight 1023 g (480–1750) and age at study 34 days (11–76). Significant GOR was defined as a reflux index >5%. Of the investigated infants, 18 subjects (78%) had significant GOR. Of this group, 16 infants had acid in the OPS on at least one occasion. Five infants did not demonstrate significant GOR and in four of these acid was not detected in the OPS. Our data indicate that as a predictor for significant GOR, litmus-testing OPS for acid has a sensitivity of 89%, specificity of 80%, positive predictive value of 94% and a negative predictive value of 67%. The difference in the incidence of acid OPS between the GOR and the No GOR group was significant (P < 0.03). Conclusion The presence of acid in the oropharyngeal secretions may help in the prediction of acid gastro-oesophageal reflux in preterm infants. The method is simple, inexpensive cheap and involves minimal disturbance. We suggest that it could aid clinical diagnosis and indicate a need for further investigation of gastro-oesophageal reflux. Received: 30 June 1998 / Accepted in revised form: 18 November 1998     

早产儿血流动力学及心功能评估的研究进展

早产儿心功能不全是新生儿重症监护室中常见的急危重症,伴随着较高的病死率,可引起严重的近期和远期后遗症。因此了解早产儿血流动力学的主要特点,并准确应用相应的临床监测方法进行早期心功能的评估至关重要。该文将对早产儿血流动力学的主要问题及心功能评估方法作一综述。     

The effect of in-hospital developmental care on neonatal morbidity,growth and development of preterm Taiwanese infants: A randomized controlled trial

Introduction

Intervention studies of developmental care for preterm infants in Western societies have shown early but unsustainable effects on child outcomes, however only a limited of studies have examined if developmental care interventions produce similar effects in Eastern cultural contexts.

Aims

To examine the effectiveness of in-hospital developmental care on neonatal morbidity, growth and development of preterm infants with very low birth weight (VLBW; birth weight < 1500 g) in Taiwan.

Methods

One hundred and seventy-eight VLBW preterm infants were randomly assigned to the clinical trial during hospitalization at three hospitals in Taiwan; the control group received five sessions of standard child-focused developmental care and the intervention group received five sessions of child- and parent-focused developmental care. Sixty-two normal term infants were also included as a comparison group. Infants were examined for morbidity, growth and developmental outcomes at term age.

Results

At study entry, more infants in the intervention group were twins or multiples than those in the control group (29% vs. 16%, p = 0.05). After adjusting for birth set, the intervention group had lower incidences of stage II–III retinopathy (odds ratio [OR] = 0.34 [95% confidence interval (CI): 0.15–0.79]; p = 0.01) and feeding desaturation (OR = 0.32 [95% CI: 0.10–1.00]; p = 0.05) and had greater daily weight gains (difference = 2.0 g/day [95% CI: 0–4.0 g/day]; p = 0.05) as compared with the control group. However, the intervention and control groups did not differ in any of the neurodevelopmental measures.

Conclusions

In-hospital developmental care has short-term benefits for Taiwanese VLBW preterm infants in reducing the risk of retinopathy and feeding desaturation as well as in enhancing weight gains at term age.     

Measurement of resting energy expenditure in infants

OBJECTIVE: The method for measurement of basal metabolic rate (BMR) using indirect calorimetry in adults is well established but is impractical in infants. METHODS: In this prospective study energy expenditure was measured using indirect calorimetry in 14 infants when sleeping and when lying quietly awake. RESULTS: Sleeping metabolic rate (SMR) was lower than energy expenditure (EE) measured in the same infants in a quiet resting state (mean difference [SD]: 297 [162] kJ/d; P < 0.005; 55 [33.4] kJ/kg per day; P < 0.005). The correlation within individuals suggests that these differences are related to the level of arousal. Awake EE, but not SMR, was significantly greater than estimated BMR using the FAO/WHO/UNU predictive equation. CONCLUSIONS: In infants, the level of arousal during measurement of EE can significantly impact on the interpretation of EE results. A standardized method for the measurement of EE in infants using indirect calorimetry is proposed.     

The ontogeny of sensory perception in preterm infants

The extra- vs intrauterine development of both visual and auditory cortical evoked response patterns was compared at 33, 37 and 40 weeks conceptional age. The maturation of visual cortical evoked responses is retarded in infants at 37 and 40 weeks conceptional age when born with a gestational age of less than 32 weeks, which thus implies a long extrauterine life span. The maturation of the auditory cortical evoked responses is not influenced by premature exposure to the extrauterine environment.The results are explained on the basis of the particular central nervous system growth spurt periods and a thus defined vulnerable period of different brain structures.     

早产儿喂养不耐受

早产儿喂养不耐受可导致早期营养不良、生长受限,对以后的行为和认知产生影响,是目前新生儿科医生面临的重要问题。喂养不耐受与早产儿胃肠功能不成熟、围生期窒息、感染等疾病因素相关。临床治疗常采用微量喂养,促胃肠动力药、口服益生菌等方法,但目前尚无统一的预防和治疗指南。