Serial Measurements of Cerebral Blood Flow Velocity in Preterm Infants during the First 72 Hours of Life

ABSTRACT. Serial measurements of cerebral blood flow velocity (CBFV) were made in 29 preterm infants, using continuous wave Doppler ultrasound. CBFV was measured in both anterior cerebral arteries and quantitative measurements of CBFV were determined using the area under the velocity curve. In all ventilated infants, CBFV increased significantly during the first 6 hours of life and continued to increase until 16 hours of age. Thereafter, CBFV remained relatively constant. This increase in CBFV was primarily the result of increased diastolic flow. Three infants who had evidence of intraventricular haemorrhage on cranial ultrasound, had similar CBFV compared with the infants with no evidence of haemorrhage. Two infants died and both demonstrated areas of periventricular leukomalacia at autopsy. These infants had a prolonged period of low CBFV. These measurements provide normal data for ventilated, preterm infants. As previously suggested in term infants, the initial rise in CBFV may be secondary to closure of the ductus although a generalized decrease in peripheral vascular resistance could also be a contributing factor. Fluctuations in CBFV rather than individual readings are probably more important in the genesis of IVH. An episode of significantly reduced CBFV is a poor prognostic sign.     

Does Caffeine Affect Cerebral Blood Flow in the Preterm Infant?

ABSTRACT. Caffeine, used for treatment of idiopathic apnea in preterm infants, may have a vasoconstrictive effect on cerebral vessels. The ensuing reduction in cerebral blood flow may play a role in the pathogenesis of ischemic brain damage. In 25 preterm infants possible changes in cerebral blood flow due to caffeine administration were assessed using Doppler ultrasound. During caffeine treatment PaCO₂ was reduced. However, no changes were found in cerebral blood flow velocity suggesting absence of major changes in cerebrovascular resistance and actual cerebral blood flow following caffeine medication.     

Cerebral Blood Flow, PaCO2 Changes, and Visual Evoked Potentials in Mechanically Ventilated, Preterm Infants

ABSTRACT. Two estimations of global cerebral blood flow (CBF) using 133-Xenon clearance were done with an interval of about one hour in 16 mechanically ventilated, newborn infants, of less than 33 weeks gestational age. In eight infants CBF was estimated just before a change in ventilator settings, and again when the Pa_co2 was stable. In the remaining eight infants small spontaneous changes in Pa_co2 occurred. The CBF-CO₂ reactivity was similar in the two groups (+67%/kPa (95% confidence interval 13–146) and 52%/kPa (24–86)) and considerably higher than the CBF-CO₂ reactivity estimated from the interindividual variation of flow and Pa_co2 (+19%/kPa (4–36)). There were no significant relations between CBF and arterial blood pressure. Flash evoked potentials (VEP) were recorded during the 133-Xenon clearances in 8 of the infants. VEP showed no relation to changes in CBF, even when the blood flow rose from the lowest levels. CBF and VEP were obtained once in 9 other infants. Among the 17 infants, the latency of the first negative wave of the VEP was not related to the CBF level. Mean CBF in the 25 infants was 12.3 ml/100 g/min (range 4.3 to 18.9), mean Pa_co2 was 4.2 kPa (range 2.3 to 6.4). Thus, CBF-CO₂ reactivity appeared to be normal in these clinically stable, mechanically ventilated, preterm infants, suggesting that their low cerebral blood flow was well regulated. The absence of a relation of CBF with VEP suggested that cerebral blood flow was not critically decreased.     

Influence of Behavioural State on Blood Pressure in Preterm Infants during the First 5 Days of Life

ABSTRACT. The influence of behavioural state on neonatal blood pressure was studied in 19 healthy preterm infants. During the first five days of life every three hours a series of oscillometric blood pressure measurements was made. During the measurements the behavioural state was scored. The predominant states were quiet and active sleep. We confirmed the age-dependency of blood pressure with a steep increase during the first day of life. After the first day blood pressure and heart rate were slightly higher when the infant was awake than when asleep. Paired comparison ( t -test) before and after spontaneous state transitions showed significant differences in median heart rate and ranges of heart rate and blood pressure, but not in median blood pressure. We conclude that especially movements influence oscillometric determination of blood pressure and heart rate.     

Postnatal Changes in Intracranial Blood Flow Velocity in Preterm Infants

ABSTRACT. Postnatal changes in intracranial arterial blood flow velocity, were studied in preterm infants of less than 34 weeks of gestation. The blood flow velocity was measured in an artery on the base of the skull, using a range-gated Doppler ultrasound velocimeter. Ten healthy infants (mean gestational age 32.5 weeks), and ten infants with transitional respiratory disease (mean gestational age 31.3 weeks) were studied at 1, 2, 5, 24 h, and 2, 3, 5 and 10 days after birth. The healthy infants showed a consistent pattern of changes on the first day, with an average reduction in mean flow velocity of 29% between 1 and 5 h. At 24 h after birth, mean flow velocity had almost returned to the level of the 1 h recording. After 24 h there was a gradual increase in systolic and mean flow velocity until 10 days, while diastolic flow velocity remained unchanged. In the infants with respiratory disease there were no systematic changes in mean flow velocity on the first day, although large individual changes were seen. After 24 h no differences were seen between the healthy infants and the infants with respiratory disease. These findings indicate a transient decrease in cerebral perfusion during early circulatory transition in healthy preterm infants, and that mild to moderate respiratory disease causes larger individual variations in intracranial blood flow velocity.     

Blood Pressure Responses to Care Procedures in Ventilated Preterm Infants

ABSTRACT. Responses of mean aortic blood pressure to sequences of routine care procedures in 22 ventilated, preterm infants were studied daily for the first 3 days of life. In the first 11 infants standard care procedures were used, whereas the next 11 infants were preoxygenated by a preceding 10% increase in inspired oxygen concentration; in these infants, chest physiotherapy was entirely omitted while the frequency of endotracheal suctioning was reduced. A total of 259 blood pressure responses were recorded. In general, responses were biphasic, consisting of an initial blood pressure drop followed by a greater blood pressure rise of longer duration. Baseline blood pressure, as well as the minimum and maximum blood pressure during the care procedures, increased with gestational age and with postnatal age. The blood pressure drop was most pronounced in the infants requiring the most intensive ventilatory support and was reduced by modifying the care procedures. The blood pressure rise was the least in the infants receiving pancuronium and phenobarbitone. Eight infants, 4 in each group, had intraventricular haemorrhage; in these infants, the care procedures induced more pronounced blood pressure drops in the first day of life when compared to the infants without haemorrhage.     

早产儿和足月儿脑性瘫痪的临床特征

目的探讨早产儿和足月儿脑性瘫痪(CP)的临床特征,确定脑损伤的病因与时间,为病因预防提供依据。方法回顾性分析2005年9月-2007年8月在安徽医科大学第一附属医院小儿神经康复中心住院的267例CP患儿的围生期脑损伤高危因素、临床特点、头颅CT和MRI表现。早产儿组102例。28周≤胎龄<37周;出生体质量1000～4000g,平均2228.82g。足月儿组165例。37周≤胎龄<42周;出生体质量2100～4600g,平均3250.18g。计量资料采用频数分布及中位数,计数资料采用频数分布、百分构成比及χ2检验进行描述与分析。结果早产儿组痉挛型双瘫高于足月儿组(χ2=7.93P<0.01),足月儿组偏瘫型(χ2=8.17P<0.01)和共济失调型(χ2=4.21P<0.05)高于早产儿组。高危因素主要顺位依次为窒息、低出生体质量、黄疸、颅内出血和双胎。早产儿组并2种以上高危因素,病理性黄疸,双胎,低出生体质量的情况较多;而足月儿组并窒息、颅内出血较多。早产儿组癫高于足月儿组(χ2=10.37P<0.01)。除癫癎外,早产儿和足月儿并发症的差异均无显著性意义(Pa>0.05)。头颅影像学方面早产儿组CP集中表现为脑室周围白质软化,足月儿CP影像学异常分布范围较广。结论早产儿和足月儿在CP类型构成、高危因素、并发症和头颅影像学方面均有差异。对早产儿早期随访、早期干预,有利于CP的早期诊断和治疗。     

Cerebral Blood Flow Reactivity in Spontaneously Breathing, Preterm Infants Shortly after Birth

ABSTRACT. In 18 spontaneously breathing, preterm infants (mean gestational age 30.3 weeks) cerebral blood flow (CBF) was investigated twice, 2 and 3 hours after birth when spontaneous changes in arterial carbon dioxide tension (P_aCO₂) and mean arterial blood pressure (MABP) were expected. Transcutaneous oxygen tension (TcO₂) was kept normal by adjusting the inspiratory oxygen fraction. In 12 infants, plasma adrenaline and noradrenaline were constant throughout the study. Changes in CBF infinity (CBF_∞) were significantly related to changes in P_aCO₂ (p=0.0001) whereas neither changes in MABP nor TcO₂ reached a significant association to changes in CBF (p=0.67 and p=1.0, respectively). The calculated CBF-CO₂ reactivity of 28.9% per kPa P_aCO₂ (95% confidence interval 16.1–43.0) is comparable to findings in older newborns and healthy adults. Only one of 18 infants developed germinal layer haemorrhage (grade I) in spite of the hypercapnic state which was observed during the first hours of life. Periventricular leucomalacia was not detected. It is suggested that the cerebral blood flow is well regulated within physiological variations of P_aCO₂ and MABP in the healthy, preterm newborn even shortly after birth.     

Cerebral Blood Flow in Preterm Infants:

No abstract available for this article.     

Compensatory Increase of CBF in Preterm Infants during Hypoglycaemia

ABSTRACT. Cerebral blood flow (CBF₀₀) was investigated in 24 preterm infants (mean 30.8 weeks of gestational age) by use of intravenous 133-Xe clearance technique while screening simultaneously for low blood glucose after birth (mean 3 hours). CBF was significantly increased in 10 infants with blood glucose lower than 1.7 mmol/l compared to normoglycaemic infants and tended to decrease rapidly after treatment. Nine of the 10 hypoglycaemic infants were monitored for cerebral function. Well defined visual evoked cortical potentials were elicit-able in all and the aEEG was not less active during the hypoglycaemic episode. Therefore, it is suggested that compensatory increase of CBF may have supported the cerebral metabolism during uncomplicated hypoglycaemia.     

Cerebral and Abdominal Arterial Hemodynamics in Preterm Infants with Patent Ductus Arteriosus

Using Doppler echocardiography we evaluated the effect of ductal shunt flow on the cerebral and abdominal arterial blood flow in 25 preterm infants. Eligible for inclusion in this study were healthy preterm newborn infants. They were divided into two groups based on their gestational age: group A, 33-36 weeks (15 infants) and group B, 28–32 weeks (10 infants). Two-dimensional Doppler echocardiograms were obtained in each infant during the first 8 hours of life and repeated every 6–12 hours until no ductal shunt flow could be detected. Flow in the ductus arteriosus, the basilar artery and the coeliac artery were examined. Closure of the ductus arteriosus occurred significantly later(p< 0.05) in group B than in group A. Pulsatility indices of flow in the basilar and coeliac arteries were high when the ductus was patent, decreasing to a fixed level with closure. This study suggests that a shunt of the patent ductus arteriosus (PDA) adversely influences the cerebral and abdominal blood flow in preterm infants.     

成比例辅助通气治疗早产儿呼吸窘迫综合征的疗效

目的观察成比例辅助通气(PAV)治疗早产儿呼吸窘迫综合征(ARDS)的疗效。方法使用Stephanie3.3型呼吸机PAV模式,采用自身前后对照,对2007年8月-2009年3月收住本科首先使用持续呼吸道正压通气(CPAP)疗效不佳且符合病例纳入标准的18例ARDS患儿改用PAV治疗,参数:呼气末正压(PEEP)为0.29～0.59kPa;后备通气设计呼吸暂停最长允许时间为10s,呼气压峰值为1.77～2.45kPa,PEEP为0.29～0.59kPa,呼吸频率(RR)为30～50次·min-1,吸气时间(TI)为0.3～0.5s,流量(FR)为8～12L·min-1;弹性阻力卸载值为50～150kPa·L-1,呼吸道黏性阻力卸载值为2.45～7.35kPa·L-1·s-1;呼出潮气量的最低容量为患儿体质量×5mL,呼出最高容量限制为患儿体质量×10mL,PIP限定为2.94kPa,最长吸气时间限定为0.7s。对比其前后1h的平均血压、RR、心率、血气分析,观察治疗效果。结果18例患儿使用PAV前后平均血压变化不明显(t=0.78,P>0.05),RR、心率明显减慢(t=11.80、8.80,Pa<0.05)...     

Perinatal Growth Retardation in Preterm Infants

Greisen, G. and Petersen, M. B. (Department of Neonatology, Rigshospitalet, Copenhagen, Denmark). Perinatal growth retardation in preterm infants. Acta Paediatr Scand Suppl 360: 43, 1989.
Perinatal and 4-year follow-up data were analysed for 137 children born after 26 to 35 weeks of gestation. All were free of severe prenatal or neonatal illness and of major handicaps. Infants who were light-for-gestation at birth were approximately 0.6 SDS smaller at 4 years than the appropriate-for-gestation infants as regards height, weight, and head circumference (p< 0.005). The McCarthy general cognitive score was reduced (p = 0.03). Motor scores, standardised for cognitive function, were also reduced (p = 0.02) indicating that motor—perhaps cerebellar—function is particularly vulnerable to perinatal growth retardation.     

Severe Hypocarbia in Preterm Infants and Neurodevelopmental Deficit

ABSTRACT. We report significant neurological abnormality at 18 months of age in 3 of 7 very low birth weight infants (≤ 1500 g), who during mechanical ventilation inadvertently became severely hypocarbic (arterial carbondioxide tension less than 2.0 kPa (15 mmHg)) at some time during the first 24 h of life. Although the number is small the outcome was significantly worse than the outcome in two fairly similar groups of infants selected as controls ( p =0.026). The infants in one of the control groups were also mechanically ventilated but remained normocapnic. Germinal layer haemorrhage (GLH) was more frequent among these infants compared with the severely hypocarbic infants ( p =0.022). The infants in the other control group was not mechanically ventilated. In all the severely hypocarbic infants the Bayley mental developmental index uncorrected for prematurity was at or below the median for the total sample ( p =0.01). The results suggest that neonatal cerebral ischaemia, for instance due to hypocarbia, is of greater prognostic significance than GLH.     

晚期早产儿研究进展

晚期早产儿以往称为近足月儿,指胎龄34～36+6周的早产儿,约占早产儿的70％,近年来晚期早产儿出生人数逐年增加,其病死率、患病率、神经发育及再入院率等均明显高于足月儿.因此,有必要加强产前保健,减少早产儿出生,并针对此类人群制定相应的监护措施,以提高整体人口素质.     

Normal Plasma-Urine Osmolality Relationship in Preterm Infants on Positive Pressure Mechanical Ventilation

ABSTRACT. Mechanical ventilation with positive pressure has been implicated in the inappropriate release of vasopressin. To examine whether such a phenomenon occurs in infancy, 26 preterm neonates with Respiratory Distress Syndrome were studied. Simultaneous urine and plasma were collected for osmolality determination during mechanical ventilation with positive end expiratory pressure of 4-8 cmH₂O. Results were plotted onto our previously described nomogram. The data show normal distribution of plasma to urine osmolality ratio in 25 out of 26 infants. These results do not support the common belief that positive pressure mechanical ventilation in the newborn with RDS provokes inappropriate secretion of vasopressin.     

Phenobarbital Prophylaxis for Hyperbilirubinemia in Preterm Infants

Phenobarbital (PB) has been used at several pediatric centers for prophylaxis against neonatal hyperbilirubinemia. However, few attempts have been made to evaluate this procedure quantitatively, and a variety of dose schedules has been proposed. Therefore, a randomized, controlled clinical trial was performed in which the effects on bilirubin disposition and on neonatal behavior was quantitated. Forty-three preterm infants were randomized into one of four dose groups and given 0, 4, 8, or 12 mg of PB per kg in a single dose within the first few hours after birth (mean 2.2 h). The total serum bilirubin disappearance rate was found to be significantly increased ( p < 0.01) only in the 12 mg/kg group. This effect was not evident until postnatal day 7. The 4 and 8 mg/kg groups were not significantly different from the control group at any time. Infant behavior was monitored by a non-invasive time-lapse filming technique. The time spent in quiet sleep was found to be proportional to the plasma PB concentration at one day of age ( r = 0.61). The infants in the 12 mg group spent a larger proportion of time in quiet sleep than the other groups ( p < 0.05). The plasma half-lives, plasma clearances and volumes of distribution of PB were similar in the three dose groups. No correlation was found between the pharmacokinetics and the gestational age of the infant. It is concluded that in order to enhance the bilirubin disappearance rate, PB has to be administered in doses that will affect behavior.     

促红细胞生成素治疗早产儿脑损伤的效果

目的探讨促红细胞生成素(EPO)在防治早产儿脑损伤中的作用。方法早产儿30例。男23例,女7例;随机分为常规治疗组、EPO治疗组,各15例。EPO治疗组于生后即开始予EPO治疗。所有患儿随诊至1岁,定期行脑电图、脑干诱发电位(ABR)检查及头颅B超等影像学检查,并于纠正胎龄40周行新生儿行为神经检测(NBNA)。结果1.EPO治疗组NBNA评分正常者占73.33%,明显高于常规治疗组(26.67%),差异有显著性(P<0.05);2.纠正胎龄1个月时二组患儿ABR异常率比较差异无统计学意义(P>0.05),随访至3~6个月时,EPO治疗组ABR异常率明显小于常规治疗组(P<0.05)。EPO治疗组后期ABR的异常程度较前明显减轻。结论早期使用EPO可改善早产儿预后,减少或减轻早产儿脑损伤。