不同胎龄早产儿早期凝血指标的变化及其临床意义

目的:研究不同胎龄早产儿早期凝血指标的变化及其临床意义。方法:选取2012年1月至2017年7月期间我院出生的新生儿392例为研究对象。根据新生儿胎龄的不同分为早期早产儿组(胎龄27~31周)78例、中期早产儿组(胎龄32~33周)102例、晚期早产儿组(胎龄34~36周)116例以及足月新生儿组(胎龄37~42周)96例。四组新生儿出生后2h内抽取静脉血检测凝血指标,包括凝血酶原时间(PT)、活化部分凝血酶原时间(APTT)、纤维蛋白原(FIB),并应用Pearson相关性分析分析新生儿胎龄与上述各项凝血指标水平的相关性。结果:早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组的出生体重以及胎龄呈逐渐上升趋势,不同组别新生儿的出生体重以及胎龄差异均有统计学意义(P0.05)。早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组PT、APTT均呈逐渐下降趋势,FIB呈逐渐上升趋势,不同组别新生儿PT、APTT、FIB差异均有统计学意义(P0.05)。Pearson相关性分析显示,新生儿胎龄与PT、APTT呈负相关(r=-0.567、-0.691,P=0.000、0.000),而新生儿胎龄与FIB水平呈正相关(r=0.623,P=0.000)。结论:不同胎龄早产儿早期凝血功能存在异常变化,新生儿胎龄与PT、APTT均呈负相关关系,与FIB呈正相关关系,临床应予以重视,及时检测其凝血指标,必要时应予以干预治疗。     

Does Thermoregulatory Feeding Occur in Newborn Infants? A Novel View of the Role of Brown Adipose Tissue Thermo genesis in Control of Food Intake

The physiological significance of the extensive deposits of brown adipose tissue (BAT) in newborn human infants has been the subject of much experimentation and discussion. Because of its large thermogenic capacity, its function has usually been viewed as preparing the infant for producing heat in response to cold exposure at birth. Newborn infants are indeed capable of precise thermoregulation for a limited time over a rather limited range of ambient temperatures, from thermoneutrality (32–34°C) down to common “room” temperatures (24–28°C). During such mild “cold-exposure”, in response to a decrease in their skin temperature, their sympathetic nervous system activity increases, and they can more than double their resting metabolic rate, principally by thermo genesis in their BAT. This review puts forward an entirely new role for BAT thermo genesis in the cyclic feeding pattern of newborn infants during their first months of life. BAT thermo genesis is proposed to be an integral element in a physiological thermoregulatory feeding control mechanism in which extended periods of very gradual cooling are interspersed with episodes of increased sympathetic nervous system activity, increased heating via BAT thermo genesis, arousal, and feeding. The cry with which the baby attracts its mother's attention is an integral part of the mechanism, as is the nutritive suckling reflex and the behavior of the mother. Initiation of feeding is attributed to a transient dip in blood glucose concentration that is due to stimulation of glucose utilization in the BAT. Termination of feeding is attributed to the high temperature brought about by the stimulated BAT thermo genesis. The duration of the urge to feed extends from the time of the cry to the time of the peak rise in temperature, when feeding stops. There is no clear Orcadian rhythm in core temperature in newborn infants, and meals occur at fairly frequent intervals both day and night in infants that are fed on demand. These physiological mechanisms are consistent with the limited information on phenomena attending spontaneous feeding in the newborn human infant and with what is known about the physiological control of feeding in rats. In rats, thermoregulatory feeding is defined as a feeding episode that occurs during a transient but marked increase in sympathetic nervous system activity that has several consequences. It stimulates BAT thermo genesis and increases body temperature. It produces a transient decline in blood glucose concentration secondary to the increased uptake of glucose by the stimulated BAT; this signals the initiation of the feeding episode. Subsequently the high temperature induced by BAT thermo genesis signals termination of the feeding episode. The size of the meal is determined by the balance between the capacity for BAT thermo genesis (heat production) and ambient temperature (heat loss). BAT thermo genesis is here viewed as an integral part of a physiological feeding control mechanism that links thermal balance with energy balance. The phenomenon is referred to as thermoregulatory feeding to distinguish it from feeding originating from other causes. As applied to human infants, the thermoregulatory feeding hypothesis supports the current practice of “feeding-on-demand”, i.e., entirely in accordance with the physiological oscillations in body temperature generated by the baby, determined by its thermal environment, mediated by oscillations in its BAT thermo genesis, and signaled by its demand for food. Whether the hypothesis has implications for feeding premature infants housed in incubators, usually fed on schedule rather than on demand, requires investigation.     

Iodine in contrast agents and skin disinfectants is the major cause for hypothyroidism in premature infants during intensive care

In 51 sick newborns the influence of two different nonionic, iodine-containing contrast agents, Amipaque (group 1) and Omnipaque (group 2) and of long-term treatment with polyvinylpyrrolidone-iodine (PVP-I) (group 3) on thyroid function was studied. In the dose given, freshly dissolved Amipaque releases roughly 100 micrograms 'free' iodide/kg body weight; this release may be even higher in the solubilized agent Omnipaque because of increased breakdown. Urinary iodine excretion was elevated in all groups on day 5 after iodine exposure. In group 1, which included 17 term newborns, the median TSH level was normal after 5 days and 2 weeks, only 1 case of transient hypothyrotropinemia was observed; T4 and T3 median levels were in the lower range of normal. In groups 2 and 3, which included 8 preterm infants of 15 newborns and 9 preterm infants of 19 newborns, respectively, the median TSH values were elevated and T4 and T3 levels were very low. Hypothyroidism was diagnosed in 6 of the 8 preterm and in 1 of the 7 term newborns of group 2. In group 3, 7 of the 9 preterm and 3 of the 10 term newborns reacted with hypothyroidism. Eight preterm and 3 term newborns had to be substituted with thyroxine. The thyroid function of term newborns was less affected by Amipaque or Omnipaque than by PVP-I. The data show that preterm infants are very sensitive to an iodine load.     

Iron release in erythrocytes and plasma non protein-bound iron in hypoxic and non hypoxic newborns

Iron is released in a desferrioxamine (DFO)-chelatable form (DCI) when erythrocytes are challenged by an oxidative stress. In β-thalassemic erythrocytes, both DCI content and release (after aerobic incubation for 24 h) are increased and correlated with the fetal hemoglobin (HbF) levels. Since erythrocytes from newborns have an extremely high content of HbF and are exposed to conditions of oxidative stress, the release of iron in these erythrocytes was investigated. The erythrocyte DCI content was increased in preterm but not in term newborns as compared to adults, while the release was increased in both preterm and term erythrocytes. The level of plasma non protein-bound iron (NPBI), which was not detectable in adults, was much higher in preterm than in term newborns. When term plus preterm newborns were divided in two groups, normoxic and hypoxic, according to cord blood pH, it was found that both iron release and NBPI were markedly higher in the hypoxic newborns compared to normoxic ones. Similar results were also obtained when the preterm and term infants were considered separately on the basis of cord blood pH. Therefore, iron release and NPBI are higher when conditions of hypoxia occur. In fact, when the values for iron release and NPBI were separately plotted against cord blood pH values, significant negative correlations were seen in both cases. NPBI was correlated with iron release seen in all the newborns and a significant part of the released iron could be recovered into the incubation medium at the end of the incubation.     

Iron Release in Erythrocytes and Plasma Non Protein-bound Iron in Hypoxic and Non Hypoxic Newborns

Iron is released in a desferrioxamine (DFO)-chelatable form (DCI) when erythrocytes are challenged by an oxidative stress. In &#103 -thalassemic erythrocytes, both DCI content and release (after aerobic incubation for 24 h) are increased and correlated with the fetal hemoglobin (HbF) levels. Since erythrocytes from newborns have an extremely high content of HbF and are exposed to conditions of oxidative stress, the release of iron in these erythrocytes was investigated. The erythrocyte DCI content was increased in preterm but not in term newborns as compared to adults, while the release was increased in both preterm and term erythrocytes. The level of plasma non protein-bound iron (NPBI), which was not detectable in adults, was much higher in preterm than in term newborns. When term plus preterm newborns were divided in two groups, normoxic and hypoxic, according to cord blood pH, it was found that both iron release and NBPI were markedly higher in the hypoxic newborns compared to normoxic ones. Similar results were also obtained when the preterm and term infants were considered separately on the basis of cord blood pH. Therefore, iron release and NPBI are higher when conditions of hypoxia occur. In fact, when the values for iron release and NPBI were separately plotted against cord blood pH values, significant negative correlations were seen in both cases. NPBI was correlated with iron release seen in all the newborns and a significant part of the released iron could be recovered into the incubation medium at the end of the incubation.     

Oxidative stress and autologous immunoglobulin G binding to band 3 dimers in newborn erythrocytes

Since birth-induced oxidative stress (OS) results in the removal of erythrocytes from the blood stream, we studied the binding of autologous IgG to erythrocyte band 3 dimers (the 170-kDa band, which marks the erythrocytes for removal) in preterm and term newborns and in adults. The 170-kDa band was present in as much as 74% of preterm, in 21% of term newborns, and in 10% of adults. During erythrocyte ageing "in vitro" (0, 24, and 48 h aerobic incubation), the appearance of the band occurred much faster with erythrocytes from newborns (particularly preterm) than with those from adults. When the blots for the 170-kDa band were quantified by scanning densitometry, it was seen that the 0 time values were significantly higher in preterm compared to term and adult values. After aerobic incubation a progressive increase in the optical density was observed in each group and the densities were higher in preterm than in the other groups. The course of iron release during the various incubations was analogous to that of the 170-kDa band blots, and significant correlations were found at 0 and 48 h. Methemoglobin formation roughly paralleled iron release. Esterified F(2)-isoprostanes (markers of OS) and O(2)(-) production in the nonincubated (0 time) erythrocytes were much higher in newborn (preterm and term) than in adult erythrocytes. Plasma free F(2)-isoprostanes were significantly higher in preterms than in terms and in terms than in adults. Plasma non-protein-bound iron (NPBI) was higher in preterm than in term newborns and not detectable in adults. In conclusion dimers of band 3 with autologous IgG are found under conditions in which OS can be detected in erythrocytes or in plasma: namely in newborns or in aged erythrocytes.     

Hormone synthesis and storage in the thyroid of human preterm and term newborns: effect of thyroxine treatment.

Iodine and thyroglobulin concentrations, as well as iodine, T3, T4 and sialic acid contents of thyroglobulin, were measured in thyroid glands collected postmortem from 42 human premature or term newborns and infants. Three groups were considered: very preterm newborns (24-32 postmenstrual weeks, < 5 days postnatal life), preterm and term newborns (34-41 postmenstrual weeks, < 5 days postnatal life) and infants (born at term, postnatal age 1-8 months). Five very preterm and seven preterm newborns received a daily dose of 10 microg/kg L-T4 for at least 3 days. Thyroid weight and sialic acid content of thyroglobulin progressed with maturation. Intrathyroidal concentrations of iodine and thyroglobulin did not increase significantly before the 42nd week of postmenstrual age. The level of thyroglobulin iodination increased during the postnatal life, except in the very preterm neonates. T4 and T3 content of thyroglobulin was directly proportional to its degree of iodination and positively related to its sialic acid content. L-T4 treatment of preterm newborns increased thyroglobulin iodination and T4-T3 content, without increasing thyroglobulin concentration in the thyroid. It was concluded that the storage of thyroglobulin and iodine in the thyroid develops around term birth. This, associated with the resulting rapid theoretical turnover of the intrathyroidal pool of T4 in Tg, could be an important factor of increased risk of neonatal hypothyroxinemia in the premature infants. The L-T4 treatment of preterm newborns does not accelerate the maturational process of the thyroid gland.     

Influence of postconceptual age on the electromyographic characteristics in newborns

The purpose of the study was to investigate the neuromuscular state in the preterm infants using surface electromyography (EMG). Ten preterm (gestational age, 31–32 weeks) and ten term infants (gestational age, 38–39 weeks) participated in the study in the second, fourth and sixth postnatal weeks. Linear and novel nonlinear parameters were used for the treatment of the interference EMG (iEMG) in four muscles (mm. bic. br. dext., trie. br. dext, tib. ant. sin., and gastr. sin.). In the preterm infants aged 33–37 weeks, both linear and nonlinear iEMG parameters were significantly lower in comparison to the term infants. Thus, the iEMG of the preterm infants was characterized by a more primitive time-domain structure and lower amplitude and spectrum frequency. In addition, unlike in term newborns, the lifetime dynamics of the iEMG parameters in the preterm infants was retarded. Thus, the motor system of a preterm infant is likely to be less prepared for postnatal life due to the shorter stay in utero. Nonetheless, the iEMG of the preterm infants may be characterized as more complex in comparison to the term newborns of the same postconceptual age. This may be attributed to the new postnatal sensory stimuli.     

Longer Gestation among Children Born Full Term Influences Cognitive and Motor Development

Children born preterm show persisting impairments in cognitive functioning, school achievement, and brain development. Most research has focused on implications of birth prior to 37 gestational weeks; however, the fetal central nervous system continues to make fundamental changes throughout gestation. Longer gestation is associated with reduced morbidity and mortality even among infants born during the period clinically defined as full term (37–41 gestational weeks). The implications of shortened gestation among term infants for neurodevelopment are poorly understood. The present study prospectively evaluates 232 mothers and their full term infants (50.4% male infants) at three time points across the first postnatal year. We evaluate the association between gestational length and cognitive and motor development. Infants included in the study were full term (born between 37 and 41 weeks gestation). The present study uses the combination of Last Menstrual Period (LMP) and early ultrasound for accurate gestational dating. Hierarchical Linear Regression analyses revealed that longer gestational length is associated with higher scores on the Bayley scales of mental and motor development at 3, 6 and 12 months of age after considering socio-demographic, pregnancy, and infant-level covariates. Findings were identical using revised categories of early, term, and late term proposed by the Working Group for Defining Term Pregnancy. Our findings indicate that longer gestation, even among term infants, benefits both cognitive and motor development.     

Streptococcus group B in meningitis and infection of newborn infants

Streptococci were isolated from the liquor or blood of 102 newborn infants and 16 infants in the first month of their life, suspected of having purulent meningitis, in 22 cases (18,5%). 5 isolated streptococcal strains were classified with group B on the basis of their cultural, biochemical and serological features. All of these strains were isolated from newborn infants during the first 3-4 days of their life. The occurrence of group B streptococci among all examined newborn infants was 4.8%; among the newborns with the positive results of bacteriological examination (73 infants) this figure was as high as 6.8%. The authors emphasize the necessity of producing, on an industrial scale, diagnostic preparations for the identification of group B streptococci playing a significant role in septic diseases and meningitides in newborns.     

Prospective means of decreasing suppurative-septic diseases in puerperae and newborn infants

The comparative analysis of the occurrence of purulent septic diseases in mothers during the puerperal period and in newborns, observed in a maternity hospital before and after the introduction of the system of keeping newborns together with their mothers, showed a considerable decrease in the morbidity rate among newborn infants (6 times) and in occurrence of mastitis among puerperae (30 times). This is attributed to a decrease in the frequency of the colonization of newborns and mothers in the puerperal period by the hospital strains of staphylococci belonging to epidemic phagotypes. The gradual elimination of staphylococci of phagotype 80, which dominated for several years, from the hospital was observed. To decrease the morbidity rate, the introduction of the system of keeping newborn infants with their mothers in all maternity hospitals of the USSR is proposed.     

Neonatal animal models of opiate withdrawal

The symptoms of opiate withdrawal in infants are defined as neonatal abstinence syndrome (NAS). NAS is a significant cause of morbidity in term and preterm infants. Factors, such as polysubstance abuse, inadequate prenatal care, nutritional deprivation, and the biology of the developing central nervous system contribute to the challenge of evaluating and treating opiate-induced alterations in the newborn. Although research on the effects of opiates in neonatal animal models is limited, the data from adult animal models have greatly contributed to understanding and treating opiate tolerance, addiction, and withdrawal in adult humans. Yet the limited neonatal data that are available indicate that the mechanisms involved in these processes in the newborn differ from those in adult animals, and that neonatal models of opiate withdrawal are needed to understand and develop effective treatment regimens for NAS. In this review, the behavioral and neurochemical evidence from the literature is presented and suggests that mechanisms responsible for opiate tolerance, dependence, and withdrawal differ between adult and neonatal models. Also reviewed are studies that have used neonatal rodent models, the authors' preliminary data based on the use of neonatal rat and mouse models of opiate withdrawal, and other neonatal models that have been proposed for the study of neonatal opiate withdrawal.     

Bilirubin and oxidative stress in term and preterm infants

Hyperbilirubinemia is the most frequent clinical problem neonatologists must deal with during the newborn period. It has been suggested that bilirubin is involved in the balance between antioxidant and pro-oxidant agents due to its antioxidant properties. However, the relevance of these effects in vivo in term and preterm infants is still debated. We performed a literature review of studies that investigated the association between total serum bilirubin (TSB) and oxidative stress in newborn infants. We found that studies in term infants give contradictory results, while studies in preterm infants suggest that the TSB increase is associated with an oxidative stress increase due to concurrent factors other than bilirubin level, such as heme oxygenase (HO) activity. Moreover, it could be speculated that low physiologic TSB values are associated with antioxidant effects, while high pathologic TSB values are associated with pro-oxidant effects. Literature data do not allow the establishment of whether if the antioxidant properties of bilirubin are important from a clinical point of view and can affect the outcome in ill infants.     

Glucose regulation in preterm newborn infants

After birth, continuous transplacental transfer of glucose is interrupted. Neonates have to provide brain and vital organs with sufficient glucose. In term newborn infants, this is accomplished through well-coordinated hormonal and metabolic adaptive changes. During the first week of life, preterm infants are at high risk of abnormal glucose homeostasis. They are at risk of hypoglycemia due to limited glycogen and fat stores that should have occurred in the third trimester. Continuous glucose infusion is always required soon after birth to maintain the glucose level. However, under such conditions, many preterm infants develop hyperglycemia. Defective islet beta-cell processing of proinsulin is likely related to hyperglycemia. There is also evidence that preterm infants are partially resistant to insulin. By contrast with adults, hepatic glucose production is not suppressed during parenteral glucose infusion. Exogenous insulin infusion partially reduces endogenous glucose production in preterm newborn infants. This treatment is efficient and safe when used with caution. More research is needed to understand the specificity of glucose homeostasis in preterm infants and to evaluate the long-term consequences of metabolic and nutritional support during early life.     

Ventilation Onset Prior to Umbilical Cord Clamping (Physiological-Based Cord Clamping) Improves Systemic and Cerebral Oxygenation in Preterm Lambs

BackgroundAs measurement of arterial oxygen saturation (SpO₂) is common in the delivery room, target SpO₂ ranges allow clinicians to titrate oxygen therapy for preterm infants in order to achieve saturation levels similar to those seen in normal term infants in the first minutes of life. However, the influence of the onset of ventilation and the timing of cord clamping on systemic and cerebral oxygenation is not known.AimWe investigated whether the initiation of ventilation, prior to, or after umbilical cord clamping, altered systemic and cerebral oxygenation in preterm lambs.MethodsSystemic and cerebral blood-flows, pressures and peripheral SpO₂ and regional cerebral tissue oxygenation (SctO₂) were measured continuously in apnoeic preterm lambs (126±1 day gestation). Positive pressure ventilation was initiated either 1) prior to umbilical cord clamping, or 2) after umbilical cord clamping. Lambs were monitored intensively prior to intervention, and for 10 minutes following umbilical cord clamping.ResultsClamping the umbilical cord prior to ventilation resulted in a rapid decrease in SpO₂ and SctO₂, and an increase in arterial pressure, cerebral blood flow and cerebral oxygen extraction. Ventilation restored oxygenation and haemodynamics by 5–6 minutes. No such disturbances in peripheral or cerebral oxygenation and haemodynamics were observed when ventilation was initiated prior to cord clamping.ConclusionThe establishment of ventilation prior to umbilical cord clamping facilitated a smooth transition to systemic and cerebral oxygenation following birth. SpO₂ nomograms may need to be re-evaluated to reflect physiological management of preterm infants in the delivery room.     

Factors that increase the contractile tone of the ductus arteriosus also regulate its anatomic remodeling

Permanent closure of the full-term newborn ductus arteriosus (DA) occurs only if profound hypoxia develops within the vessel wall during luminal obliteration. We used fetal and newborn baboons and lambs to determine why the immature DA fails to remodel after birth. When preterm newborns were kept in a normoxic range (Pa(O(2)): 50-90 mmHg), 86% still had a small patent DA on the sixth day after birth; in addition, the preterm DA wall was only mildly hypoxic and had only minimal remodeling. The postnatal increase in Pa(O(2)) normally induces isometric contractile responses in rings of DA; however, the excessive inhibitory effects of endogenous prostaglandins and nitric oxide, coupled with a weaker intrinsic DA tone, make the preterm DA appear to have a smaller increment in tension in response to oxygen than the DA near term. We found that oxygen concentrations, beyond the normoxic range, produce an additional increase in tension in the preterm DA that is similar to the contractile response normally seen at term. We predicted that preterm newborns, kept at a higher Pa(O(2)), would have increased DA tone and would be more likely to obliterate their lumen. We found that preterm newborns, maintained at a Pa(O(2)) >200 mmHg, had only a 14% incidence of patent DA. Even though DA constriction was due to elevated Pa(O(2)), obliteration of the lumen produced profound hypoxia of the DA wall and the same features of remodeling that were observed at term. DA wall hypoxia appears to be both necessary and sufficient to produce anatomic remodeling in preterm newborns.     

Behavioral arousal in newborn infants and its association with termination of apnea

Arousal is an important protective mechanism that aids in the resolution of obstructive sleep apnea in adults and children, but its role in neonatal apnea has not been investigated. The primary aim of the present study was to determine the role of arousal in the termination of apnea in preterm infants. Videorecording was used to identify spontaneous behavioral arousal in a group of healthy full-term (n = 7) and preterm (n = 10) infants before and during polygraphic monitoring of cardiorespiratory variables and in a group of preterm infants with apnea (n = 10) during similar polygraphic monitoring. Spontaneous arousal rates (mean +/- SE) in full-term infants before and during polygraphic monitoring were 0.18 +/- 0.03 and 0.23 +/- 0.07 episodes/min, respectively. Corresponding values in nonapneic preterm infants were 0.24 +/- 0.03 and 0.24 +/- 0.02 episodes/min. In apneic preterm infants, mean spontaneous arousal rate during polygraphic recording was 0.26 +/- 0.02, but it was considerably higher during apneic sleep periods (0.59 +/- 0.17) than during nonapneic sleep periods (0.25 +/- 0.01). The frequency of occurrence of arousal was significantly higher (P less than 0.005) in long vs. short apnea, mixed vs. central apnea, and severe vs. mild apnea. Although a clear association between arousal and apneic resolution was observed in preterm infants, lack of arousal responses in a large number of apneic episodes suggests that behavioral arousal is not essential for the termination of apnea in these infants.     

A chronobiological study on the relation between heart rate and QT interval duration in newborn infants

The relation between heart rate and QT interval is the result of the autonomic nervous system control on cardiac function in healthy adults; accordingly, chronobiological studies have shown that adult subjects have circadian rhythms of heart rate (expressed as R-R interval) and QT interval in phase. We have employed chronobiological methods to study heart rate and QT interval relation in 10 newborn infants, who are known to have an immature cardiac control. Findings from this study indicate that not all the newborns show circadian rhythms of heart rate and QT interval and that when both rhythms are present they do not correlate like in the adults. Likely, this lack of relationship between heart rate and QT interval in newborns is due to different maturational stages of the newborns studied. As a practical implication, in newborn infants, mathematical correction of QT interval by heart rate is not a reliable method.     

Cerebral oxygenation is highly sensitive to blood pressure variability in sick preterm infants

Objectives

The significance of blood pressure variability (BPV) for cerebral oxygenation in extremely preterm infants has not been explored, though BPV may well be associated with end organ injury. We hypothesized that increased BPV in sick preterm infants, by exceeding the cerebral autoregulatory capacity, is associated with cerebral oxygenation changes which closely follow the blood pressure fluctuations. We assessed the autoregulatory capacity in the early postnatal period, by determining the correlation between BPV (mmHg²) and coherence of mean arterial blood pressure (MABP mmHg) and cerebral oxygenation (tissue oxygenation index, TOI %).

Study Design

Thirty-two preterm infants of mean gestational age of 26.3 (±1.5) weeks were studied on the first 3 postnatal days. Spectral analysis (Coherence and transfer-function gain analysis) was used to calculate coherence of MABP and TOI; BPV was quantified using power spectral density of MABP.

Results

Overall, maximum Coherence showed a trend for positive correlation with BPV (n = 32, p = 0.06). Infants identified as clinically unstable with documented brain injury (n = 7) had high Coherence values at low BPV. Separate analysis of stable infants (excluding the 7 critically ill infants) revealed a significant association between maximum Coherence and BPV (n = 25, p = 0.006).

Conclusions

Fluctuation in cerebral oxygenation is closely associated with increased BPV in preterm infants undergoing intensive care. Moreover, in the critically sick preterm infant, blood pressure-dependent variations in cerebral oxygenation occur even with relatively lower BPV, suggesting they have severely impaired autoregulation, and placing them at greater vulnerability to cerebral injury arising from blood pressure fluctuations.     

益生菌制剂治疗极低出生体重儿喂养不耐受的临床研究

目的探讨益生菌制剂对极低出生体重儿（very low birth weight infant,VLBW）喂养不耐受的影响。方法将56例极低出生体重儿随机分成治疗组和对照组,每组28例。2组均予静脉营养及早产儿配方奶喂哺,治疗组在早产儿配方奶喂哺时添加益生菌制剂,每次0．5g,3次／d,2组同时记录恢复出生体重时间、达全胃肠喂养时间及黄疽消退时间。结果治疗组恢复出生体重时间、达全胃肠喂养时间均显著短于对照组（P〈0．01）,治疗组黄疸消退时间也明显缩短（P〈0．05）。微生态制剂治疗过程中无不良反应发生。结论益生菌制剂可改善极低出生体重儿喂养不耐受,促进患儿体重增长,缩短达到全胃肠喂养时间,值得推广应用。