Developmental patterns of heart rate and variability in infants with persistent apnea of infancy

During periods of regular breathing, heart rate is slower and more variable in healthy (no history of respiratory distress syndrome) prematurely born infants with persistent apnea, relative to full-term control infants of comparable post-conceptional ages. We tested the hypothesis that the cardiovascular differences may be linked to the persistent apnea, rather than premature birth, by assessing heart rate and variability in full-term infants with persistent apnea. Thus, resting heart rate and variability were compared in full-term infants with apnea of infancy, prematurely born infants with persistent apnea, and full-term control infants. Full-term infants with persisting apnea showed slower heart rates than control infants, beginning at 4 months after birth, and enhanced heart rate variability beginning at 6 months. Healthy prematurely born infants with persistent apnea showed cardiovascular alterations similar to those of full-term infants with apnea; these alterations differed from those observed in very premature infants with histories of respiratory distress. The postnatal development of cardiovascular aberrations in infants with persistent apnea suggests that mechanisms accompanying apneic events may contribute to long-term alterations in autonomic control.     

早产儿生后早期血清降钙素原生理变化规律的研究

目的探讨生后不同时间和不同胎龄的早产儿血清降钙素原(PCT)生理变化规律。方法无感染新生儿217例,其中足月儿115例,早产儿102例,后者依据胎龄分为3个亚组:30～32周(30例)、33～34周(35例)、35～36周(37例),分别研究其生后0～12 h、13～24 h、25～36 h、37～48 h、49～72 h、73～96 h、97～120 h、121～144 h PCT水平变化规律。结果新生儿生后随着时间推移,PCT逐渐升高,24 h左右达高峰,其后逐渐下降,生后96 h左右降至儿童正常值。早产儿组PCT峰值晚于足月儿组,约在生后36 h出现,此后缓慢下降,96 h左右降至和足月儿数据相当。30～32周早产儿生后PCT数值维持低浓度水平,37～48 h逐渐升高,升高时间晚于33～34周及35～36周早产儿。结论新生儿在生后早期PCT有一个先增高后下降的动态变化过程,其中早产儿分泌高峰要迟于足月儿。32周以前早产儿生后36 h之内PCT水平较低。     

早产儿血清表皮生长因子测定的临床意义

目的：表皮生长因子与胎儿器官发育和功能成熟密切相关,该研究探讨早产儿窒息及早产儿坏死性小肠结肠炎患儿血清中表皮生长因子含量及其临床意义。方法：采用放射免疫方法检测10例足月新生儿和35例早产儿生后血清表皮生长因子浓度。结果：35～37周和28～34周早产儿血清表皮生长因子含量0.617±0.22μg/L,0.540±0.31μg/L明显低于足月新生儿0.723±0.18μg/L,差异有显著性(P<0.01);窒息早产儿与足月儿相比血清表皮生长因子水平降低更为明显0.446±0.24μg/Lvs0.723±0.18μg/L;坏死性小肠结肠炎早产儿与足月儿比较血清表皮生长因子浓度没有明显降低0.771±0.44μg/Lvs0.723±0.18μg/L,差异无显著性。结论：血清表皮生长因子水平与胎龄有关;窒息可使表皮生长因子水平降低。     

Maturation of cardiac control in full-term and preterm infants during sleep

ECG and respiration were recorded from 13 full-term and 8 preterm infants at 2–5-week intervals during sleep at home in the first year of life. Average pulse interval in both quiet and active sleep was minimum at postnatal ages between 4 and 10 weeks, with the minimum during quiet sleep being significantly smaller for preterm (409 ±22 (SE) msec) than for full-term (445 ±9 msec) infants. The minimum average pulse interval of preterm infants was smaller than the pulse interval of full-term infants at any postconceptional age, and a smaller average pulse interval and smaller variations in pulse interval in preterm infants during quiet sleep persisted until a postnatal age of 7 months. The pulse interval variations attributable to respiration varied substantially with age. The results indicate that developmental changes in cardiac rate control are functions of both postnatal and postconceptional age, with the post-conceptional age at birth setting the mean level of pulse interval, a level which is then altered by development linked to postnatal age.     

晚期早产儿健康状况及其影响因素探讨

目的 研究北京市海淀区妇幼保健院1年内,晚期早产儿的出生率、病死率、各系统并发症及早产相关因素等,为进一步建立系统、有效的临床防治方案提供依据.方法 前瞻性统计2007年1月1日至12月31日,北京市海淀区妇幼保健院出生的全部新生儿.胎龄35-37周的晚期早产儿为观察组,生后24 h内检查血、尿、便常规、血气分析、血电解质、监测微最血糖、胸片、头颅B超及心脏彩超;随机选每月1日出生的足月新生儿为对照组,详细记录两组并发症.并对观察组母亲年龄、孕期感染、妊高征、糖尿病、贫血、胎膜早破、羊水异常、脐带异常、胎盘异常、双胎进行分析比较.结果 晚期早产儿333例,出生率为2.71%(333/12 286);并发症以高胆红素血症发生率最高(33.6%),其次为呼吸系统疾病发生率(16.8%)、低血糖(9.0%)、颅内出血(8.1%)、贫血或红细胞增多症(5.7%)、消化系统疾病(5.4%),较足月儿组明显增高(P<0.05);妊高征、贫血、胎膜早破、双胎妊娠是导致晚期早产儿早产的主要高危因素;其病死率为1.20%(4/333),明显高于足月新生儿的0.08%,差异有统计学意义(P<0.05);晚期早产儿住院时间(5.1 d±3.90 d)明显高于足月新生儿(3.2 d±1.61 d)(P<0.05).结论 北京市海淀区妇幼保健院晚期早产儿的出生率为2.71%;其并发症发生率、病死率高于足月新生儿,住院时间也较足月新生儿长;高胆红素血症为最常见并发症;妊高征、贫血、胎膜早破、双胎妊娠是导致晚期早产儿的主要早产因素.儿科医生应重视晚期早产儿,常规收人新生儿科观察治疗.     

Temperament characteristics of premature infants in the first year of life

Parenting preterm infants in the first months after hospital discharge is challenging. Although preterm infants are considered to be difficult, preterm temperament at less than 3 months is unknown empirically. The purpose of this analysis was to investigate the 6-week temperament characteristics of preterm infants in comparison with standardized norms of full-term infants. The sample of 74 infants with gestational ages at birth between 24 and 32 weeks were enrolled in a study of preterm infant neurobehavioral outcomes. Mothers rated temperament at 6 weeks, 6 months, and 12 months of age (adjusted for prematurity). At 6 weeks the premature infants were significantly less rhythmic (regular), more distractible (soothable), less approaching (more withdrawing), and less intense than standardized norms for full-term infants. From these data we conclude that premature infants may be initially more challenging to parent. Temperament moderated over time but remained significantly lower in persistence at 12 months. Considerable change in temperament in the first 12 months of life may be influenced by biological and environmental factors common to the premature birth experience.     

Bone measurements of infants in the first 3 months of life by quantitative ultrasound: the influence of gestational age, season, and postnatal age

Background: There are a few quantitative ultrasound (QUS) studies of bone status for Chinese children. Objective: To evaluate the clinical application and to investigate the bone status of neonates and young infants with QUS. Materials and methods: An ultrasound bone sonometer was used to measure the bone speed of sound (SOS) of the tibia in 542 neonates within 3 months of birth. Results: At birth, no significant difference of SOS was found between boys and girls, but there was a significant difference of SOS between premature infants and full-term infants. The SOS in neonates born during spring and summer was significantly lower than those born during autumn and winter. There were significant correlations between SOS and gestational age, and between bone SOS and birth weight in appropriate for gestational age (AGA) infants. Multiple regression analysis found that gestational age and infant birth season were two important factors influencing SOS. During the first 3 months, there was no significant difference in SOS between sexes. The SOS of infants showed an inverse correlation with postnatal age, and the decrease of bone SOS with age in premature infants was more marked than in full-term infants. Conclusions: QUS is suitable for evaluating bone status in infants with high precision. The study offers some basic data for neonates and young infants.     

TRANSEPIDERMAL WATER LOSS IN NEWBORN INFANTS

Abstract. Using a method described earlier, the evaporation rate (ER) was studied at different humidities in 12 newborn infants born after 25 to 30 weeks of gestation and 10 infants born after 32 to 35 weeks. Transepidermal water loss (TEWL) was estimated in 32 infants born after 25 to 39 weeks of gestation. The ER values were highest in the infants with the lowest gestational age and the susceptibility to changes in ambient humidity was also greater at lower gestational ages. An exponential relationship was found between TEWL and gestational age, TEWL being 15 times higher in infants born after 25 weeks of gestation than in full-term infants.     

Influence of the mode of delivery on perinatal mortality in infants less than 32 weeks gestational age

Survival rate of 96 low-birth-weight infants less than 32 weeks post-conceptional age at birth was studied in relation with the mode of delivery. Twenty-two infants were delivered by elective cesarean section because of abnormalities during pregnancy with 3 neonatal deaths. Seventy-four infants were born after untreatable premature onset of labor with 9 intrapartum and 7 neonatal deaths. Poor prognosis was associated with gestational age (less than 29 weeks), non cephalic vaginal delivery and multiple births. In these cases, cesarean section should be discussed.     

组织多普勒成像对早期新生儿心室功能的评价

目的 应用组织多普勒成像（TDI）检测新生儿房室环运动，探讨不同胎龄早期新生儿左右心室功能的特点。方法 采用TDI技术检测生后3—7d的36例胎龄32～36周早产儿（早产儿组）和33例足月新生儿（足月儿组）二、三尖瓣环运动，测量收缩期峰值速度（Sa）、舒张早期峰值速度（Ea）及舒张晚期峰值速度（Aa），以脉冲多普勒显像测量舒张期二、三尖瓣口血流E峰及A峰峰值速度。结果 早产儿组各部位Ea、Sa均显著低于足月儿组，早产儿组三尖瓣环Ea／Aa显著低于足月儿组，两组Aa及E／Ea无显著差异；各部位Ea、Sa与胎龄及出生体质量均呈正相关。结论 早产儿左、右室收缩及舒张功能均低于足月儿，早期新生儿心室功能与其出生前成熟程度有关，早产儿及足月新生儿生后早期左室舒张功能均明显增强。     

Cardiorespiratory events recorded on home monitors: the effect of prematurity on later serious events

OBJECTIVE: To describe severe alarms on home-documented monitoring in infants born prematurely. METHODS: In infants born at a post-menstrual age (PMA) less than 35 weeks, a polysomnography was performed before discharge. A heart rate less than 50 beats per minute (bpm) for more than 3 seconds or an apnea lasting for more than 15 seconds with a heart rate less than 60 bpm were defined as abnormal. These babies were given cardiorespiratory home monitoring with memory. Serious alarms on the home monitor were defined as heart rate less than 50 bpm for more than 3 seconds. RESULTS: Of 1058 infants, 96 infants needed cardiorespiratory home monitoring. Sixty-one infants showed alarms at home. The mean post-conceptional age (PCA) when alarms stopped was 46 weeks. Seventeen patients had serious alarms above the PCA of 50 weeks. There was a significant negative correlation (r = -0.46 and p = 0.0002 by Spearman's rank correlation) between the PMA at birth and the PCA at which the last alarm was noted CONCLUSION: Prematurely born infants with an abnormal polysomnography at discharge are at high risk for developing acute events at home. A younger PMA at birth correlates with a higher risk of alarms at a later PCA.     

Early growth and development in low-birthweight infants following treatment in an intensive care nursery.

Sixty-seven appropriate-for-date infants with gestations less than 33 weeks were followed for 12 months after their term dates. All had been born after September 1970. None received hypercaloric alimentation as neonates. Growth from the expected date of delivery was compared with that of 24 normal full-term infants and with accepted growth standards. The boys did not differ from the controls or the standard in mean weight, length, and head circumference, in weight and height indices, or in velocity of weight and linear growth. The girls had a slower velocity of weight growth for the first six months and had significantly lower weight indices at 12 months than did their controls. Velocity of linear growth, height indices, and mean length and head circumference for the girls were similar to those of the control standards. Gross central nervous system defects occurred in 22.5% of the boys but in none of the girls. More than one half of the abnormalities were hydrocephaly. The mean post-conceptional developmental quotient was 110 for the girls and 108 for the boys.     

Breathing patterns and heart rates at ages 6 weeks and 2 years.

Forty-two randomly selected, full-term, healthy infants underwent 24-hour electrocardiographic recordings and breathing movements at about ages 6 weeks (median age, 43 days; range, 34 to 61 days) and 2 years (median age, 26 months; range, 21 to 35 months). The number and duration of apneic pauses of 3.6 seconds or longer were analyzed. Periodic apnea was defined as a sequence of three or more apneic pauses, each separated by fewer than 20 breaths. All other apneic pauses were defined as isolated. Median heart rates and respiratory rates, which were measured during regular breathing, decreased from 137/min and 35/min to 98/min and 21/min, respectively. The total duration of periodic apnea remained unchanged (median, 0.06 min/h vs 0.05 min/h). Although the median frequency of all isolated apneic pauses decreased from 3.6/h to 2.5/h, the number of those that were longer than 6 seconds increased from 0.37/h to 0.80/h, leading to an increase in the proportion of these pauses, among all isolated apneic pauses, from 10% at age 6 weeks to 32% at age 2 years. Only one apneic pause in one infant at age 6 weeks, but eight pauses in six children at age 2 years, were longer than 15 seconds. A knowledge of such normal variability in the duration of apneic pauses in older infants and young children is essential for the interpretation of pneumograms and alarms while monitoring breathing movements.     

Neonatal resuscitation and preventive continuous positive pressure ventilation]

One of the aspects of prematurity in neonates is the respiratory distress syndrome. Although treatment with mechanical ventilation reduced the mortality rate, bronchopulmonary dysplasia still develops in many neonates. We have attempted to reduce intubation and mechanical ventilation by using, in the delivery room, humidified and warmed gas with fractional inspired oxygen as low as possible to obtain SaO2 between 85 and 95%. The gas was administered with a face mask using continuous positive air pressure 3-5 cm H2O. Seventeen out of 66 premature neonates born before the 35th week of gestation were ventilated immediately (n = 11) or subsequently (n = 6). Seven out of 26 infants (27%) born between 30 and 32 weeks required mechanical ventilation. In contrast, ventilation was necessary for eight out of 16 premature neonates born before the 29th week of gestation. Mortality rate was 6% (4/66) in the latter group (< 29 weeks), and only one neonate developed bronchopulmonary dysplasia.     

Renal control of sodium and fluid balance in newborn infants during intravenous maintenance therapy.

Changes in accumulated fluid and sodium balance during intravenous maintenance fluid therapy has been studied in 38 newborn infants with different clinical disorders and gestational ages 28-42 weeks. The results from the infants born before 36 weeks of gestation (preterm) have been compared with the result from infants born after 36 weeks. Three different saline infusions 10, 20 and 40 mEq Na1/2/1000 ml 5.5% glucose have been given. The infusion rate has in preterm neonates been 3.3 ml/kg and hour and in the more full-term neonates been 3.6 ml/kg and hour. The study lasted for 5-8 hours. Urine was collected by spontaneous voidings in plastic bags. The balances were calculated as the difference between the amount given intravenously, and the amount excreted in the urine. In the more full-term neonates Na1/2 balance became increasingly negative with the 10 mEq solution, just balanced with the 20 mEq solution and increasingly positive with the 40 mEq solution. A different response was found in the preterm neonates. The natriuresis was higher and the sodium balances were increasingly negative with both the 10 and 20 mEq solutions. With the 40 mEq solution the negative balance tended to level off. The fluid balances were fairly well maintained in all infants regardless of the sodium concentration in the infusate.     

Immunogenicity of hepatitis B vaccine in term and preterm infants

Some studies have suggested that decreased seroconversion rates might be found in premature infants with low birthweight (< 2000 g) following administration of hepatitis B vaccine at birth. The aim of the present investigation was to evaluate possible differences in seropositive rates between full-term and preterm infants after primary vaccination, in particular when gestational age or birthweight is very low. Two-thousand and nine neonates born to HBs Ag-negative mothers were vaccinated with 10 μg of recombinant hepatitis B virus (HBV) vaccine, from May 1991 to October 1994. Children with infections, congenital malformations or serious illnesses were excluded. HBV vaccine was administered intramuscularly, on the fourth day of life and again at 1 and 6 months of age. A 1-ml blood sample was drawn from each infant 1 month after the third vaccine dose for determination of the level of anti-HBs antibody. The response to HBV vaccination was evaluated in 241 preterm (gestational age < 38 weeks) infants and 1727 term neonates. No statistical difference was observed in the distribution of anti-HBs antibody level, either between preterm infants (< 38 weeks) and newborns of normal gestational age, or between low birthweight (< 2500 g) and normal weight infants. The results suggest that preterm and low birthweight infants (< 2500 g) respond to HBV vaccine in the same measure as normal-term infants.     

Breath amplitude modulation of heart rate variability in normal full term neonates

The relationship between heart rate variability and respiration patterns was investigated using spectral analysis techniques in nine full-term infants whose ages ranged from 39-75 h. All the infants were studied during sleep, although no attempt was made to classify rapid eye movement or nonrapid eye movement states prospectively. The data obtained were examined to determine which aspects of neonatal breathing patterns are correlated with heart rate variability. Three spectral regions of heart rate variability could be identified: a very low frequency region below 0.02 Hz; a low frequency region from 0.02-0.20 Hz; and a high frequency region above 0.20 Hz. The dominant heart rate variability activity in these neonates was seen in the very low and low frequency regions, with little activity in the high frequency regions. In contrast to older infants and adults, respiration and heart rate variability were not strongly related through a high frequency region respiratory sinus arrhythmia but rather through a breath amplitude sinus arrhythmia which occurs in the low frequency region of the spectrum. The prominent very low frequency activity and the low frequency activity ascribed to breath amplitude modulation may result from autonomic nervous system mediation of chemoregulation.     

惠州地区不同胎龄早产儿甲状腺功能检测及影响因素分析

目的 探讨不同胎龄早产儿甲状腺功能特点及其影响因素。方法 选择本院新生儿科2012年1~12月收治的早产儿为研究对象。按胎龄分为28~31周组、32~34周组及35~36周组,选取同期本院产科出生的健康足月新生儿30名为对照组。分别在生后第1天和第14天检测新生儿静脉血血清游离三碘甲状腺原氨酸（FT3）、游离甲状腺激素（FT4）以及促甲状腺激素（TSH）,并分析其影响因素。结果 各组新生儿生后14天血清FT3、FT4、TSH水平均显著低于生后第1天（P〈0.05）。35~36周组和对照组生后第1、14天血清FT3、FT4水平均高于28~31周组和32~34周组,32~34周组高于28~31周组（P〈0.05）。TSH水平生后第1天35~36周组和对照组高于28~31周组和32~34周组,生后第14天28~31周组和32~34周组高于35~36周组和对照组（P〈0.05）。早产儿生后第1天影响甲状腺功能的因素为胎龄、出生体重及窒息、缺氧缺血性脑病、呼吸窘迫征综合征、休克等严重疾病;生后第14天影响因素为胎龄和出生体重。结论 早产儿下丘脑-垂体-甲状腺轴发育不成熟,生后14天检测甲状腺功能具有重要临床意义。     

Postnatal changes in blood spot 17-hydroxyprogesterone level in healthy preterm and full-term neonates

Blood spot 17OH-P concentrations were determined in 14 healthy premature (mean birthweight 1439 g, mean gestational age 30 weeks) and full-term newborn infants (mean birthweight 3532 g, mean gestational age 39.2 weeks) during the first five weeks of life to provide reference data for infants with various gestational and postnatal ages. It was demonstrated that with advancing age there was an abrupt fall in 17OH-P from 296.2 +/- 84.1 nmol/l on the first day to 101.2 +/- 19.5 nmol/l on the 7th day (p less than 0.001) and 75.7 +/- 8.7 nmol/l (p less than 0.05) on the 14th day in premature infants. In full-term neonates its initial value is much lower (90.1 +/- 12.5 nmol/l) and its fall during the first week is much less pronounced (51.5 +/- 6.5 nmol/l, p less than 0.01). Comparing the postnatal changes in 17OH-P in the two groups it proved to be significantly higher in premature than in full-term infants at all ages except for the 4th week. When blood spot 17OH-P values were studied as a function of gestational age at the age of 5 days a significant inverse relationship was found between the two parameters. It is assumed that in addition to placental 17OH-P production and perinatal stress, renal salt wasting may also account for the long lasting elevation of 17OH-P plasma level seen in premature infants.     

初产足月儿与经产足月儿宫内生长水平差异的研究

目的 制定不同胎龄初产足月儿与经产足月儿宫内生长百分位曲线,研究分娩产次对宫内生长潜力的影响。方法 采用整群取样法于2013年4月至2015年9月对深圳市两家医院出生的胎龄37~41周单胎足月儿进行体格生长现场测量。曲线拟合应用Lambda-Mu-Sigma（LMS）法。结果 获得了14 529例胎龄37~41周初产、经产足月儿各胎龄出生体重、身长、头围、胸围、顶臀长均值,并制定了其10th、25th、50th、75th、90th百分位曲线。经产足月儿上述5项指标的百分位曲线的形态和增长趋势与初产足月儿一致,但37~41周各胎龄经产足月儿上述5项指标的均值及百分位曲线值均高于初产足月儿。除胎龄41周组初产与经产组顶臀长比较差异无统计学意义外,其余各胎龄组5项指标均值比较差异均有统计学意义（P < 0.05）。结论 胎龄37~41周经产足月儿各胎龄体重、身长、头围、胸围、顶臀长5项指标宫内生长水平均高于初产足月儿,提示分娩产次是宫内生长潜力重要的影响因素。