Characteristics of arterial stiffness in very low birth weight premature infants

Premature birth is a factor of increased blood pressure in adulthood. Little is known about the physiologic characteristics of the arterial bed in neonates. The aim of this study was to characterize in vivo the arterial compliance in neonates and its maturation profile in very low birth weight (VLBW) premature infants. A group of stable, VLBW premature infants was compared with a control group of near term neonates. The abdominal aortic wall distensibility coefficient (DC) and whole-body arterial compliance (WBAC) were determined using specifically designed noninvasive methods, based on ultrasonic measurements in combination with synchronous, beat-to-beat recording of aortic pulse pressure (PP). On the fifth day of life, WBAC and the CD were lower in VLBW premature infants than in controls. Furthermore, WBAC and the DC remained unchanged in VLBW premature infants 7 wk after birth. In conclusion, VLBW premature infants are characterized as early as the fifth day of life by high arterial stiffness, which persists when they reach their theoretical term. It can be speculated that early alteration of arterial elastic properties may pave the way for long-term elevation of arterial pressure in VLBW premature infants.     

Prolonged ventilation and intact survival in very low birth weight infants

A requirement for prolonged ventilation (>28 days) has been associated with a poor outcome in infants. We postulated that in the present population of infants who usually receive antenatal steroids and post-natal surfactant, prolonged ventilation in discrete episodes, i.e. discontinuous intermittent positive pressure ventilation (IPPV), would have a better outcome than a requirement for prolonged ventilation continuously from birth (continuous IPPV) and, in addition, that an abnormal ultrasound scan appearance would be a reliable predictor of poor outcome in infants requiring prolonged ventilation. All very low birth weight (VLBW) infants ventilated for at least 28 days (prolonged ventilation) were identified from a prospectively maintained database. At 1 year of age, neurodevelopmental status was assessed and abnormal neurodevelopmental outcome diagnosed if the infant's Griffiths developmental quotient was at least two standard deviations below the mean and/or they had impairment with disability. Of 417 VLBW infants, 41 required prolonged ventilation (30 continuous and 11 discontinuous). In the continuous IPPV group, 18 and one in the discontinuous IPPV group died or had abnormal neurodevelopmental outcome ( P<0.01). All eight infants with major cranial ultrasound abnormalities died or had abnormal outcome ( P<0.01). CONCLUSION: prolonged ventilation can be associated with intact survival, but not in very low birth weight infants with evidence of significant brain injury.     

Hyperkalemia in very low birth weight infants.

PURPOSE: To assess the frequency and pathogenesis of hyperkalemia in the very low birth weight infant. METHODS: Infants who weighed less than 1000 gm at birth were prospectively entered into the study within 12 hours of birth. Potential risk factors for hyperkalemia were assessed. Body weight, fluid and electrolyte balance, serum levels of sodium and potassium, creatinine clearance, fractional sodium excretion, and urine sodium/potassium ratio were measured every 8 hours for 72 hours. Measurements of plasma renin, serum aldosterone, and plasma atrial natriuretic factor were made at study entry and repeated when hyperkalemia (serum potassium greater than 6.5 mmol/L) occurred or at 72 hours. Infants in whom hyperkalemia developed were compared with those in whom it did not. RESULTS: Thirty-one infants completed the study; hyperkalemia developed in 16 (51.6%). The only difference in the occurrence of perinatal complications was the more frequent occurrence of pH less than 7.20 in infants with subsequent development of hyperkalemia. Creatinine clearance, urine output, and potassium excretion were significantly lower in the hyperkalemia group during the first 24 hours. Serum potassium concentration at 24 hours was inversely related to urine output in the prior 24 hours. Fractional sodium excretion, urine sodium/potassium ratio, and levels of renin, aldosterone, and atrial natriuretic factor did not differ between groups. CONCLUSIONS: Hyperkalemia is a frequent complication in very low birth weight infants. Infants with low urinary flow rates during the first few hours after birth are at greatest risk for the development of hyperkalemia.     

Six-year follow-up of early physiotherapy intervention in very low birth weight infants

Eighty very low birth weight infants assigned to neurologically normal or at-risk groups on the basis of a neurodevelopmental score were previously described. Infants were assigned to physiotherapy or control groups, and the effect of physiotherapy was assessed at 1 year. At-risk infants had a significantly lower developmental quotient than the normal group and no beneficial effect of physiotherapy was shown. Of the original 80 subjects, 49 were reassessed at a mean age of 74.7 months. As observed previously, physiotherapy until 1 year did not influence subsequent outcome in either normal or at-risk children. At-risk and normal children had similar mean developmental quotients at 6 years, but the locomotor score of at-risk children was significantly below that of normal children. Cerebral palsy occurred in 6 of 24 at-risk vs 0 of 25 normal subjects (P less than .01) and remedial therapy was recommended in 17 of 24 at-risk subjects vs 6 of 25 normal subjects (P less than .001). These results confirm that the neurodevelopmental score predicts a risk for either cerebral palsy or soft neurological problems, and early physiotherapy is of questionable benefit in preventing such problems.     

极低体重儿呼吸暂停的有关问题

早产儿呼吸暂停 (ａｐｎｅａｏｆｐｒｅｍａｔｕｒｉｔｙ ,ＡＯＰ)常发生于矛盾睡眠期 ,与呼吸中枢调节功能不成熟有关 ;呼吸暂停发生的频率及严重程度常与胎龄成反比。当呼吸暂停 >15～ 2 0ｓ ,或呼吸显著不规则时 ,可影响组织的氧合状态 ,尤其是在极低体重儿 ,呼吸暂停与发生     

Bone growth with low bone mineral content in very low birth weight premature infants

We report serial measurements of bone mineral content (BMC), bone width (BW, a measure of appositional bone growth), and the ratio of BMC:BW by photon absorptiometry of the left radius through the first 10 wk of life in 38 very low birth weight premature infants (birth weight less than 1300 g, gestational age less than 32 wk). Fifteen of 38 infants developed bronchopulmonary dysplasia (BPD) and as a group they could not be distinguished from the 23 infants without BPD, despite the high association between BPD and metabolic bone disease. As BPD occurred in the smaller patients, the BPD group had a significantly lower mean birth weight and mean gestational age as compared to controls (950 +/- 125 g versus 1119 +/- 149, and 28.0 +/- 0.8 versus 29.0 +/- 1.3 wk). For both control and BPD groups, BMCs did not differ and remained relatively unchanged throughout the first 10 wk of life, lagging significantly behind the intrauterine rate as defined by measuring BMC in 175 infants of varying gestational ages during the first few days of life. BW also did not differ during this period between groups. BW did increase significantly in both groups (from 3.2 +/- 0.3 to 3.9 +/- 0.4 mm in the controls and from 3.0 +/- 0.3 to 3.8 +/- 0.4 mm in the BPD group), but remained significantly delayed compared to the intrauterine rate. In both groups, BMC remained relatively constant despite increasing BW and thus BMC/BW decreased during the first 10 wk of life (from 11.5 +/- 1.3 to 10.2 +/- 1.9 in the controls and from 11.0 +/- 1.3 to 8.6 +/- 2.2 in the BPD group).(ABSTRACT TRUNCATED AT 250 WORDS)     

极低出生体质量儿视网膜病变筛查和高危因素分析

目的研究出生体质量≤1500g的早产儿视网膜病(ROP)发生率和临床高危因素,探讨预防小早产儿视网膜病的有效措施。方法回顾性分析2006年8月1日—2008年7月31日期间,在新生儿重症监护室住院的107例出生体质量≤1500g早产儿ROP筛查的结果,以发病组为观察组,非ROP为对照组,进行统计学分析。结果早产儿ROP的发生率为33.64%,Ⅰ期11例,Ⅱ期13例,Ⅲ期12例,检出时间为(245.36±12.85)d。妊娠并发症胎盘早剥和严重的早产儿并发症,增加了ROP的发病率;ROP的发生率与胎龄及出生体质量成反比,双胎及多胎妊娠不影响ROP的发生;对ROP的病因进行单因素分析发现,胎龄、出生体质量、抗生素使用时间、吸氧时间、血氧分压、肺表面活性物质的使用、支气管肺发育不良、机械通气、呼吸暂停与ROP有关(P<0.05);通过Logistic回归分析发现呼吸暂停、血氧分压和出生体质量是高危因素(P均<0.05)。结论呼吸暂停、血氧分压和出生体质量是ROP的高危因素,避免血氧波动有助于降低ROP的发生率。     

Educational status and school-related abilities of very low birth weight premature children

Eighty-eight premature children with birth weights less than or equal to 1500 g were evaluated at ages between 7 and 8 years old to determine their academic status in comparison with those of a matched full-term group. Results showed that a much higher proportion of the premature children required special educational interventions (48%) than either the full-term children (15%) or the New York State public elementary school population (10%). More than half of the premature children who received educational intervention were neurologically impaired or had below normal intelligence. The entire group of premature children differed significantly from the matched full-term group on IQ score and on tests of verbal ability, school achievement, and auditory memory. Lower socioeconomic status children performed significantly less well on each type of these measures and on a measure of attention than children of the higher socioeconomic status group. There was an interaction of prematurity and social class on Full Scale IQ, verbal tests, academic achievement, and attention, with lower socioeconomic status premature children scoring lowest on these measures. The subset of premature children normal in both IQ and neurologic status did not differ significantly from a matched normal full-term group on any cognitive measures other than arithmetic ability, but they continued to have significantly lower academic achievement scores.     

Effect of a bovine surfactant in very low birth weight premature infants with congenital pneumonia

15 VLBW-infants, who were classified to suffer from congenital pneumonia, were treated with a bovine surfactant. Mean gestational age was 25.5 weeks (range 23-27 weeks), mean birth weight was 700 g (range 530-930 g). Surfactant was instilled intratracheally at a mean dose of 41 mg/kg body weight (b.w.) (range 30-50 mg) 8 h after birth (range 6-12 h), if the fraction of inspired oxygen (FiO2) was greater than 0.5 or the peak inspiratory pressure (PIP) was greater than 22 cm H2O (b.w. less than 750 g) or greater than 25 cm H2O (b.w. 751-1000 g). Retreatment up to a total maximum of 4 doses of surfactant was permitted. Surfactant treatment reduced FiO2 from a pretreatment value of 0.79 to 0.50 one hour after application, however, 12 h later FiO2 had increased again to 0.75. Ventilation pressures showed a slight decrease during 12 h after surfactant treatment. 6 infants received 1 dose, multiple doses were given to 9 infants. 5 infants survived, 4 infants died from respiratory failure, 4 from sepsis and 2 from severe intracranial haemorrhage.     

238例极低出生体重早产儿的生长速率和影响因素

目的 观察极低出生体重早产儿住院期问的生长速度及营养支持情况,研究影响其生长的因素.方法 采用回顾性调查的方法,收集2005年1月1日至2006年6月30日我国不同地区10所三甲医院檄低出生体重早产儿的临床资料,对影响早产儿生长的因素进行分析.结果 共有238例符合条件的极低出生体重早产儿,出生胎龄为(30.9±1.9)周,出生体重(1313±129)g.生后第1周～第6周平均体重生长速率分别为-7.2、14.2、13.6、13.7、14.2、14.8 g/(kg·d).肠内、外营养开始平均时间分别为(3.4±2,3)d和(3.1±1.7)d,总热卡达120 kcal/(kg·d)平均时间为(21.3±11.6)d,喂养奶量达150 ml/(kg·d)平均时间为(23.4±10.8)d.恢复出生体重后平均生长速率为(13.8±3.5)g/(kg·d),平均住院时间(39.8±13.9)d.出生时小于胎龄者较适于胎龄者恢复出生体重后的平均生长速率快[14.4 vs 13.2 g/(kg·d),t=2.703,P<0.05].结论 平均生长速率较快组[≥15 g/(kg·d)]与较慢组[<15g/(kg·d)]相比,出生胎龄差异无显著性,但出生体重低、接受肠内肠外营养早.大多数极低出生体重早产儿在住院期间不能达到正常胎儿在官内的生长速率.更积极的肠内肠外营养,可能有利于极低出生体重儿生后的早期牛长.     

Successful direct extubation of very low birth weight infants from low intermittent mandatory ventilation rate

It is common practice to use endotracheal continuous positive airway pressure for various time periods up to 24 hours before attempting extubation in infants who are mechanically ventilated. A few studies in newborns have indicated that airway resistance is increased through small endotracheal tubes. This increases the work of breathing and the likelihood of subsequent ventilatory failure. In this study, 27 very low birth weight infants who were 1/2 to 28 days old at the time of extubation were randomly divided into two groups. One group of 13 study infants were extubated directly from intermittent mandatory ventilation rates of six to ten per minute, and the other 14 control infants were placed on continuous positive airway pressure through endotracheal tubes for six hours prior to an attempt to extubate. There was no difference between the two groups in gestational age, postnatal age, weight, or severity of lung disease at the time of extubation. All 13 study infants were successfully extubated without significant apnea or respiratory acidosis. Of the 14 control infants, only seven were successfully extubated; six infants had significant apnea and in one infant respiratory acidosis with pH 7.13 and PCO2 65 developed while receiving continuous positive airway pressure (13/13 v 7/14, P less than .005). The seven infants who failed the preextubation trial of continuous positive airway pressure were later extubated from low intermittent mandatory ventilation rates without significant apnea or respiratory acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Severe pre-eclampsia and infants of very low birth weight.

The effect of severe pre-eclampsia on the outcome of infants of very low birth weight was studied in a prospective case control study of 35 pairs of infants of comparable gestation. Significantly more infants were delivered before the onset of labour and by caesarean section in the group with pre-eclampsia. These babies tended to be smaller and had a higher incidence of hyaline membrane disease, patent ductus arteriosus, pulmonary air leak, and hypotension. They also required more intensive treatment with oxygen and mechanical ventilation. The significant difference in birth weight was still apparent at 2 years of age. Although the mean psychomotor developmental index and the incidence of specific neurodevelopmental impairments were not significantly different between the two groups, survivors in the group born to pre-eclamptic mothers had a significantly lower mean mental developmental index, and significantly more of these children had one or more impairments compared with the control group at 2 years of age.     

Physiology of infants with very low birth weight

Advances in neonatal management have resulted in dramatic increases in survival in infants with birth weights less than 1,500 g. Extensive basic science and clinical research has led to a more comprehensive understanding of the physiological differences between the VLBW infant and larger neonates. Meticulous attention must be paid to appropriate fluid, electrolyte, nutrition, and temperature maintenance to achieve homeostasis and growth. Additionally, the clinician must be aware of the diagnostic and treatment modalities for the common complications seen in the premature infant to minimize mortality and long-term morbidity.     

有关极低出生体重儿的几个问题

1　何谓极低出生体重儿 ?出生体重≤ 15 0 0 ｇ的新生儿称为极低出生体重儿 (ｖｅｒｙｌｏｗｂｉｒｔｈｗｅｉｇｈｔｉｎ ｆａｎｔ ,ＶＬＢＷＩ)。此类新生儿胎龄应在33周以下 ,若超过 33周 ,则此极低出生体重儿为小于胎龄儿。2　极低出生体重儿发生率如何 ?哪些原因可以引起 ?