Blood-brain barrier permeability in "healthy" infected and stressed neonates.

The assessment of the blood-brain barrier permeability (BBBP) showed that BBBP values were higher in stressed neonates and those with bacterial meningitis than in "healthy" infants or neonates with aseptic meningitis. The BBBP determination may be helpful in differentiating bacterial from aseptic meningitis; the high BBBP should be considered in the management of stressed neonates.     

Polymorphonuclear leukocyte adherence and chemotaxis in stressed and healthy neonates

Defects in polymorphonuclear neutrophil (PMN) adherence and chemotaxis in neonates are thought to be an important cause of their increased susceptibility to overwhelming bacterial infection. Few studies of these functions have been carried out in stressed neonates who are at even greater risk of infection. PMN adherence and chemotaxis were examined in 33 stressed neonates with acute lower respiratory illness, 13 healthy neonates, and 43 healthy adults using whole blood PMN adherence and chemotaxis assays. PMN chemotaxis was significantly decreased in stressed neonates (locomotion index of 38.4 +/- 9.7 micron) compared with that of healthy neonates (48.9 +/- 12.8 micron, p less than 0.01) or adults (61.6 +/- 11.9 micron, p less than 0.001). PMN chemotaxis was studied during illness and recovery in 13 of the 33 stressed neonates and showed significant improvement during recovery (41.6 +/- 9.9 and 53.2 +/- 11.9 micron, respectively, p = 0.012). PMN adherence was decreased in stressed neonates (1.4 +/- 1.6%) compared with that of adults (12.3 +/- 11.4%, p less than 0.01) but was similar to that of healthy neonates (1.1 +/- 1.4%). These findings suggest that further impairment of PMN chemotaxis in stressed neonates helps account for their increased susceptibility to overwhelming bacterial infection.     

Functional analysis of neutrophil granulocytes from healthy, infected, and stressed neonates.

Neutrophil granulocyte function was assessed in 17 well term infants, 14 stressed infants, and eight infants with group B streptococcal infection. Chemiluminescence production elicited by opsonized zymosan or by a wild strain of type III group B streptococci, as well as phagocytosis and killing of streptococci, were measured. Chemiluminescence production by PMNs of term neonates in response to opsonized zymosan or group B streptococci was equal to that of adult controls. In contrast, six of nine stressed or infected neonates had depressed CL responses upon zymosan challenge. When opsonized type III group B streptococci were used to elicit CL, seven of ten stressed or infected infants had markedly depressed responses. Phagocytosis, as determined by a radiolabeled bacterial uptake technique, was normal in the healthy and stressed neonates. Depressed CL production by the PMNs of stressed or infected neonates was associated with impaired intracellular bactericidal activity, however. These studies indicate that stressed or infected neonates have impaired leukocyte metabolic activation that may be associated with depressed bactericidal activity. Such impairment may contribute to the morbidity and mortality observed in serious neonatal infections.     

Hyperglycemia in stressed small premature neonates.

The metabolic responses to a constant glucose infusion were measured in 30 premature infants, 700 to 1,550 gm. The study included 18 stressed premature infants who needed assisted ventilation, and 12 control premature infants. Metabolic measurements were similar in both groups in the cord and preinfusion samples. In the first postinfusion sample, glucose, cortisol, and glycerol values were higher in stressed than in control premature infants. Hyperglycemia was seen in 13 of stressed and in only one of control premature infants. Stressed infants who became hyperglycemic in the first postinfusion sample were then compared to stressed euglycemic infants. Insulin levels were higher, glycerol levels similar, but cortisol levels lower in stressed hyperglycemic than in stressed euglycemic premature infants. The etiology of hyperglycemia in stressed premature infants cannot be attributed to hypoinsulinemia or to hypercortisolemia, and is not associated with increased glycerol levels. There was no difference in mortality between stressed hyperglycemia and stressed euglycemic infants; stress, rather than hyperglycemia, was related to mortality.     

Serial measurements of thoracic impedance and cardiac output in healthy neonates after normal delivery and caesarean section.

Thoracic electrical impedance measurements were serially performed during the 1st, 2nd, 8th and up to the 32nd hour of life in two groups (V and S) of healthy infants. In group V, all 24 infants were delivered vaginally, in group S, all 24 infants were delivered by caesarean section for obstetrical reasons. Basal thoracic impedance (Zo), heart rate (HR), stroke volume (SV) and cardiac output (Q) were determined on each examination. In group V, Zo increased from 31.9 to 34.0 ohm between 2 hours and the last recording between 8 and 32 hours. SV decreased from 4.1 to 3.4 ml between 2 and 4 hours and was accompanied by a decrease of Q from 560 to 450 ml/min. Heart rate slowed from 129 to 115 beats/min between 2 hours and the last recording at greater than or equal to 8 hours. In group S, Zo increased from 32.2 to 35.9 ohm between 2 and 8 hours. Mean SV increased from 3.6 to 4.4 ml between 8 and 32 hours and heart rate slowed from 131 to 113 beats/min between 1 and 8 hours. No significant differences were observed between the groups. The accuracy of the impedance--SV and Q data cannot be validated. For the most part they compare favourably with values previously obtained by soluble gas methods. Serial changes may reflect not only decreasing shunts and/or increasing aeration but also changes in total fluid volume of the lungs, intra- or extravascular. The precision of the measurements is good since reproducibility of single SV and Q determinations is higher than with standard dilution techniques. The data obtained may serve as baseline values for comparison with data in infants of the same age with various anomalies.     

Diminished bactericidal capacity for group B Streptococcus in neutrophils from "stressed" and healthy neonates

This study compared the bactericidal capacity of polymorphonuclear leukocytes (PMNs) from neonates and adults for type Ic group B Streptococcus (GBS), and examined the effect of severe stress on the bactericidal capacity of PMNs from newborn infants. PMNs were obtained from three study groups: 26 adults, 13 healthy neonates (cord blood), and 29 stressed neonates. Stress was defined as an acute respiratory illness or bacterial infection requiring assisted ventilation. Bacterial killing was assessed using a fluorochrome microassay and PMNs adherent to glass coverslips. PMNs from stressed infants killed significantly fewer GBS than PMNs from adults (P less than 0.001 at both time points). PMNs from healthy infants also demonstrated reduced killing compared with adults (P less than 0.01 at 60 min; P less than 0.001 at 90 min). There was no significant difference in bacterial killing between stressed and healthy neonates and no correlation between bactericidal capacity and age at time of study, gestational age, birth weight, peripheral leukocyte count, or Apgar scores. Therefore, the bactericidal capacity for GBS by PMNs from neonates is diminished; however, it is not further compromised by stress.     

Behavioural response to pain in healthy neonates.

A bedside technique for evaluating the behavioural response of healthy neonates to pain was assessed. Thirty six term infants (median gestational age 40 weeks; median postnatal age 4 days) and 31 preterm infants (median gestational age 34 weeks; median postnatal age 4 days) were assessed at the cotside for their response to heel preparation and heel lance for routine blood sampling. The facial actions of brow bulge, eye squeeze, nasolabial furrow, and open mouth were noted, and also the presence or absence of crying. Thirty five (97%) term and 26 (84%) preterm infants showed an increase in the number of behaviours in response to heel lance. Brow bulge and nasolabial furrow were seen most often, and occurred more often than crying in the two groups. There was good interobserver agreement (94%). The consistency of response and the high degree of interobserver agreement makes this method of behavioural assessment of acute pain of use in healthy neonates.     

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.     

Bradycardia and associated respiratory changes in neonates.

Electrocardiogram and patterns of respiration were recorded continuously in 9 newborn infants having episodes of bradycardia. The episodes were not associated with demonstrable apnoea, either by using an apnoea mattress or by visual observation. The ''non-apnoea'' associated bradycardia was always associated with changes in respiratory pattern, of which three different forms could be identified. These were prolonged apnoea if the apnoea alarm failed to trigger, short episodes of respiratory abnormalities associated with body movement (possibly in rapid eye movement sleep), and minor changes in respiratory pattern. It may be appropriate to incorporate a period of delay in heart rate monitoring systems before the alarm sounds, in a similar manner to apnoea alarm systems. We should rely more on heart rate in conjunction with apnoea alarms to detect problems, or produce better systems which detect respiratory flow.     

Brain calcification in severely stressed neonates receiving parenteral calcium

Morphologic evidence for calcium salts within the brains of severely stressed neonates at autopsy correlated to the mean daily parenteral dose of calcium gluconate (P less than 0.01). Survival analysis indicated that parenteral administration of calcium contributed a negative effect to predicted survival (P less than 0.05).     

Exercise-induced electrocardiographic changes in children with congenital aortic stenosis.

The relationship of exercise-induced electrocardiographic changes to severity of obstruction in congenital aortic stenosis was studied in 44 children. Twelve subjects, with ST segment depression of 1 mm or more lasting 0.08 seconds after the J Point, had left ventricular-aortic peak systolic pressure differences (gradients) ranging from 54 to 112 mm Hg. The remaining 32 children had less than 1 mm or no ST segment depression. Thirty-one of these had gradients ranging from 10 to 48 mm Hg and one had a gradient of 52 mm Hg. Vectorcardiograms, electrocardiograms, and chest roentgenograms were not useful in the identification of the severity of the lesion. The study suggests that children with severe gradients develop electrocardiographic ST segment changes with exercise, thereby helping to select those patients who should have catheterization studies to delineate the severity of the lesion. In those with a normal exercise test, cardiac catheterization may be safely delayed, but the exercise test should be repeated to identify those who develop progressive obstruction.     

Sugar malabsorption in healthy neonates estimated by breath hydrogen.

Carbohydrate malabsorption in 110 healthy, term neonates was studied by estimating expired hydrogen (H2) before and after a feed on day 6 or 7. Carbohydrate malabsorption was assumed to be present if the infant excreted > 20 parts per million (ppm) H2. The frequency of carbohydrate malabsorption in 49 breast-fed infants was 25% (n = 12), in 35 infants fed a 7.5% lactose formula it was 31% (n = 11), in 26 infants fed a formula containing 1% lactose and 7.3% maltodextrin it was 15% (n = 4). These differences in frequency were not significant. Peak H2 concentration of the malabsorbers in each group, indicating the degree of carbohydrate malabsorption, was 64, 52, and 32 ppm respectively. The degree of carbohydrate malabsorption did not differ significantly between the breast-fed and the high lactose formula groups, but both groups differed from the low lactose group. H2 excretion was studied for 5 months in an exclusively breast-fed infant. In the first 2 months high concentrations were found and the infant produced 3-5 stools a day. In the next 3 months however, most H2 estimations were normal and only 1-2 stools a week were passed. With the introduction of solids, daily bowel movements promptly reoccurred. Frequency of carbohydrate malabsorption in newborn infants is fairly high and is primarily related to the lactose intake. The frequency and degree of carbohydrate malabsorption were comparable in breast-fed infants and in infants fed on a high lactose formula; this differs from results previously reported.     

Accelerated ventricular rhythm in healthy neonates

Accelerated ventricular rhythm is similar in rate to the original sinus rhythm. Although 19 cases have been reported in healthy neonates without congenital disease, it is seen with some regularity at tertiary care paediatric cardiac centres. Accelerated ventricular rhythm carries good prognosis, but it is frequently misdiagnosed as ventricular tachycardia and is, thus, unnecessarily treated. The present report describes a case of a neonate who was not properly diagnosed after birth and who was inappropriately treated.     

健康新生儿的胃电图研究

目的：研究健康新生儿的胃电图。方法：20个健康足月新生儿胎龄37～39周,男11例,女9例,出生时阿氏评分平均为9.3±0.4分,无窒息,无器质性疾病,母乳喂养。采用体表胃电图,分别于出生后第1（第12小时）,7,14,21,28 天记录空腹和餐后体表胃电图各30 min。计算胃电图的以下参数: 主频、不同慢波节律的百分比、主频不稳定系数、功率比。结果：在所有新生儿均可记录到与成人类似的体表胃电图波形,新生儿出生后第1~28天餐前的正常胃电节律为（38. 2±4.9）%～（39.7±3.5）%,胃动过速节律为（23.7±5.4）%～（23.5±4.3）%,胃动过缓节律为（38.1±5.5）%～（36.8±3.9）%,不同年龄时期餐前与餐后相比无明显差别（P>0.05）。新生儿出生后第1~28天餐前主频为2.38±0.5 cpm～2.59±0.1 cpm ,餐后与餐前相比差异无显著性（P>0.05）,第14,21,28天餐前、餐后的主频较第1,7天高(P<0.05);生后第21,28天餐前、餐后的主频不稳定系数较第1,7,14天低(P<0.05),餐后与餐前相比差异无显著性（P>0.05）,生后第1～28天餐后餐前功率比差异无显著性（P>0.05）。结论：健康新生儿的胃电图参数与健康成人、儿童明显不同,胃电主频、正常胃电节律百分比较低,胃电主频随年龄增长逐渐升高。［中国当代儿科杂志,2007,9（4）：364-366］     

Blood pressure in full-term healthy neonates

The blood pressure (BP) of 46 healthy full-term infants was studied in the first 6 consecutive days of life using the Dinamap. The BP gradually increased with age to peak at 4 or 5 days of age before subsiding a little at 6 days. There was a significant increase in BP values from the second to the third day of life in both the systolic and diastolic pressures during the waking state but not during sleep. The waking and sleeping BP, almost identical in the first day, diverged with increasing age, although no significant difference could be demonstrated between the respective values during the 6 days of study in systolic, diastolic, or mean arterial pressure. BP values obtained in the left and right upper limbs and right lower limb were similar for the respective days, with minor variations in pattern. The waking and sleeping heart rate, identical on the first day, also diverged with increase in age but again no significant difference was observed on the first 6 days. There was no correlation between the BP and heart rate on any of the 6 days. However, a positive correlation between the daily mean systolic pressure and heart rate only in the waking state was observed over the course of the 6-day study period.