Effect of tracheal suction on oxygenation, circulation, and lung mechanics in newborn infants

Transcutaneous PO2, heart rate, and aortic blood pressure were measured i 10 mechanically-ventilated newborn infants to assess the degree and course of hypoxaemia, and to monitor the cardiovascular and respiratory changes during tracheal toilet. Five infants weighed less than 1250 (mean 994), g and 5 infants weighed greater than 1750 (mean 2216) g. During tracheal suction the TcPO2 fell from 68 +/- 27 (mean +/- SD) to 43 +/- 23 mmHg, and the heart rate from 144 +/- 8 to 123 +/- 25 beats/minute, but the blood pressure increased from 44 to +/- 24 to 49 +/- 24 mmHg. Hypoxaemia (TcPO2 less than 50 mmHg) occurred in 7 of 8 initially well-oxygenated infants when suctioned. The decrease in TcPO2 was similar for both groups of infants. It was greater in infants with controlled ventilation and an F1O2 greater than or equal to 0.8 than in infants with intermittent mandatory ventilation and an F1O2 less than 0.8. The TcPO2 fall correlated well with the TcPO2 during the control period but not during the time that the infants were disconnected from the respirator. A critical re-evaluation of routine tracheal toilet is needed.     

Cardiorespiratory response to feeding in newborn infants.

Milk feeds were given through indwelling nasogastric tubes to 14 infants with respiratory distress. Similar cardiorespiratory disturbances were observed when the infants were fed (5 ml/kg per feed) human milk, cow's mild, or distilled water. Pao2 fell after a feed but recovered to the prefeed value at 30 minutes, at which time Paco2 had fallen and the respiratory rate had increased. No changes in pH, heart rate, or blood pressure were observed. Portal sinus pressures rose after feeding in association with an increase in central venous pressure. In contrast, when the ill infants were fed human milk at a volume of 2-5 ml/kg per feed no consistent changes in any of the measurements were found. These studies suggested that the cardiorespiratory effects were related to volume displacement resulting from feeds being introduced into the stomach. The relation of the increase in central venous pressure and the magnitude and direction of shunting in infants with the respiratory distress syndrome is uncertain. Adverse effects may be avoided by giving smaller, and therefore even more frequent, feeds.     

Effects of maternal pethidine on infants' developing breast feeding behaviour

The aim of this quasi-experimental study was to examine the effects of maternal pethidine during labour on the developing breast feeding behaviour in infants in the first 2 h after birth compared with infants not exposed to pethidine. Forty-four healthy infants were observed immediately after birth. They were placed skin-to-skin on their mothers' chests. The development of mouth and sucking movements as well as rooting behaviour and state of sleep/wakefulness were noted. The observer was blind as to the pain relief the mother had received during labour. Of the 44 mothers 18 had received pethidine. The main findings were that infants exposed to pethidine had delayed and depressed sucking and rooting behaviour. In addition, a smaller proportion of infants exposed to pethidine started to suckle the breast. Rooting movements which are expected to be vigorous at 30 min after birth were affected both by administration of pethidine and a longer second stage of labour. It is suggested that the differences found in sucking behaviour may be a central effect of pethidine. Depression of rooting movements in the pethidine group may be caused by exhaustion due to a longer second stage of labour and administration of pethidine. It is recommended that pethidine-exposed mother-infant couples stay together after birth long enough to enable the infant to make the choice to attach or not to attach to the nipple without the forceful helping hand of the health staff.     

Effect of feeding on ventilation and respiratory mechanics in newborn infants.

Measurements of ventilation and respiratory mechanics were made before and after tube feeding in 24 infants. In 12 infants with the respiratory distresssyndrome tidal volume tended to fall after feeding; as the respiratory rate increased after feeding; as the respiratory rate increased after feeding, minute ventilation remained unchanged. Hypoventilation is therefore unlikely to be the cause of hypoxaemia after feeding. Compliance, resistance, and the work of breathing showed no changes after feeding. In 12 healthy infants feeding had no effects on pulmonary function. There was a slight rise in compliance and a tendency for work of breathing to fall after feeding. Respiratory rate, tidal volume, and minute ventilation remained unchanged. There was therefore no evidence of adverse effects of feeding on any of the factors measured. It is suggested that hypoxaemia without hypoventilation after feeding in infants with pre-existing respiratory distress syndrome might be attributable to a reduction in functional residual capacity associated with a greater extent of airways closure than before feeding.     

The analysis of sucking behaviour in newborn infants.

A special video camera devised by the author and a fiberscope were used to film the neonatal sucking response of 50 low-risk full-term newborn infants on the 5th day after birth. Analysis of the sucking behaviour showed that the sucking movements consist mainly of a peristaltic tongue movement and two kinds of negative pressure; that the peristaltic tongue movements are synchronized with the jaw movements; that infants actively adapt to a varying environment; and that the sucking movements change to minimize the energy required.     

Ghrelin and feeding behaviour in preterm infants

The importance of early life events in the development of metabolic diseases is well recognized. Early postnatal environment, including nutrition, is key to future health, and this is particularly true for preterm infants. It is important that these infants receive sufficient nutrients to prevent growth restriction and promote neurodevelopment, while minimizing predisposition to metabolic diseases later in life. Feeding habits are the fundamental elements of nutrition and are influenced by many factors, including personal and familial habits, socioeconomic status, and cultural environment. In the last decades, there has been an important scientific interest toward the comprehension of the molecular and neural mechanisms regulating appetite. In these networks, act many peptide hormones produced in brain or gut, among which ghrelin is important because of its action in the short-term regulation of food intake and the long-term regulation of body weight. Ghrelin stimulates appetite and plays a role in regulating feeding behaviour. Ghrelin levels vary from fetal life through to early adulthood, with the highest levels observed in the very early years. Cord ghrelin levels have been evaluated in term and preterm newborns and high ghrelin levels have been observed in small-for-gestational age newborns and in newborns with intrauterine growth restriction. Moreover, ghrelin has been detected in term and preterm human breast milk, suggesting that it may play a role in the development of neuroendocrine pathways regulating appetite and energy homeostasis in early life. However, more research is required to better define ghrelin's role in breast milk and on feeding behaviour.     

Effects of delivery by caesarean section on lung function in healthy newborn infants

With the aim of extending previous studies showing differences in lung function after birth between infants delivered vaginally (VD) and by Caesarean section (CS) we investigated lung volumes, ventilation, efficiency of ventilation, and lung mechanics in 24 healthy, full term infants with no clinical signs of respiratory disease, 12 after VD and 12 after CS. Measurements were made on two occasions: 2 and 26 hours after birth. At 2 hours no differences in any measured quantity were found between the groups. The only difference found 24 hours later was that the average thoracic gas volume (TGV), was lower in infants after CS than after VD. The difference in functional residual capacity was, however, not significant. This means that the difference in TGV, previously also found by other workers, did not affect the ventilated air space. Our results do not support the theory of general inferiority in lung performance after birth in healthy, full term infants without respiratory disease delivered by CS.     

Effects of exclusive formula or breast milk feeding on oxidative stress in healthy preterm infants.

BACKGROUND: Compared to formula, breast milk is considered to have superior antioxidant properties and consequently may reduce the occurrence of a number of diseases of prematurity associated with oxidative stress. AIMS: To test whether the antioxidant properties of breast milk in healthy premature infants are different to those of formula milk by comparing vitamin E levels in milk and determining the excretion of malondialdehyde (MDA) in urine. METHODS: Vitamin E was measured in the breast milk of 20 mothers who had given birth prematurely. Urinary MDA was measured in 10 exclusively breast milk fed and 10 exclusively formula fed healthy preterm infants receiving no vitamin supplements. MDA was measured after derivatisation with 2,4-dinitrophenylhydrazine and consecutive HPLC with UV detection. RESULTS: Urinary MDA concentrations were consistently very low (0.074+/-0.033 microM/mM Cr and 0.078+/-0.026 microM/mM Cr in breast and formula fed infants respectively) and not significantly different between healthy breast milk and formula fed infants. Both breast and formula milk contained satisfactory levels (0.3-3.0 mg/100 ml) of vitamin E. CONCLUSION: Antioxidant properties of both breast milk and formulae are sufficient to prevent significant lipid peroxidation in healthy premature infants.     

Atrial natriuretic peptide and renin-aldosterone relationship in healthy newborn infants.

Plasma atrial natriuretic peptide (ANP) and aldosterone concentrations, and plasma renin activity (PRA) were measured by radioimmunoassay concurrently in 20 healthy full term infants, in cord blood, at 24 hours after birth and on the 4th day of life. ANP and aldosterone increased significantly at 24 hours and was persistently elevated on the 4th day of life. PRA remained unchanged during the first four days of life. In cord blood, ANP concentrations were correlated with aldosterone concentrations (r = 0.49, p less than 0.05) and hematocrit (r = 0.58, p less than 0.02). At the 24 hours of life, plasma ANP concentrations were correlated with weight loss observed on the 4th day of life (r = -0.70, p less than 0.005), while the percentage changes in plasma aldosterone concentrations were correlated with percentage changes in systolic blood pressure (BP) (r = 0.49, p less than 0.05). These findings suggest that during the early newborn period ANP and aldosterone act as an integrated system which has a role in regulation blood pressure and intravascular volume homeostasis.     

健康新生儿静息能量消耗的研究

目的　检测我国健康新生儿静息能量消耗值 (REE) ,评估不同因素对其的影响。方法通过开放式间接能量测定仪 (DeltatracTMⅡ ,芬兰 )对 15 4例出生体重 2 5 0 0～ 3 999g的健康新生儿 (男75名 ,女 79名 )进行REE检测 ,与Schofield预计公式所得的预计值进行比较 ,同时比较性别和分娩方式对新生儿REE的影响。结果　健康新生儿的REE平均实测值为 ( 2 0 1 8± 2 5 4)kJ/ (kg·d) ,预计值为 :( 2 2 6 1± 4 8)kJ/ (kg·d) ,两者之间差异有显著性 ,预计值比实测值高出 12 0 4%。性别及分娩方式对新生儿REE无影响。结论　现有的预计公式并不适用于临床估算新生儿能量消耗 ,对新生儿进行间接能量测定是了解其能量消耗的较好方法。本研究推荐中国健康新生儿 (出生体重 2 5 0 0～ 3 999g)静息能量消耗值为 ( 2 0 1 8± 2 5 4)kJ/ (kg·d) ,95 %可信区间为 ( 15 2 0～ 2 5 1 6)kJ/ (kg·d)。