Biomedical subjects
Publications and source records attributed to N Rutter.
gamma-Glutamyltransferase activity was measured serially in newborn infants. Median activity was 94 units/l, with the 95th centile at 243 units/l. It was unrelated to gestation. Significant increases occurred after treatment with phenobarbitone and with the introduction of oral feeding after parenteral nutrition. It was a poor indicator of total parenteral nutrition (TPN) liver damage.
Skin permeability to drugs was assessed in the newborn infant using an in vitro method. Excised skin samples were studied in a Franz-type cell, and permeability to 0.1 M sodium salicylate was measured. Fourteen samples were studied, from infants of 25-41 weeks gestation and up to 8 days old. Gestation markedly affected skin permeability to salicylate, absorption being 10(2)-10(3) times greater in infants of 30 weeks gestation or less than in term infants. There are important implications for the high permeability of the preterm infant's skin; accidental poisoning from absorption of topically applied agents can easily occur, and the percutaneous route offers an alternative method of therapeutic drug administration.
Changes in transepidermal water loss were used to measure skin damage caused by removal of electrocardiograph electrodes in 20 preterm infants. Electrodes secured by conventional adhesive damaged the skin, leading to a potentially dangerous increase in skin permeability. In contrast, those secured by karaya gum caused no skin damage.
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Teenage sisters were found to have hereditary spherocytosis when they presented in aplastic crisis associated with otherwise asymptomatic parvovirus infection. Such patients may present a source of cross-infection to others at risk.
Percutaneous respiration was studied in 32 newborn infants between 25 and 41 weeks gestation, using a closed skin cell attached to the abdomen. Gas exchange rates in the first few days of life were 6-11 times faster in infants below 30 weeks gestation than in term infants (mean O2 absorption 25.0 vs. 206.5 ml/m2/h, and CO2 excretion 26.0 vs. 294.6 ml/m2/h), but rates were similar by 3 weeks of age. Increasing the ambient oxygen concentration resulted in a non-linear increase in oxygen absorption, particularly in the most immature infants. Below 30 weeks gestation, O2 absorption increased from a mean of 206.5 ml/m2/h in air, to 357.2 ml/m2/h in 40% oxygen and 573.5 ml/m2/h in 90% oxygen. We estimate that an infant below 30 weeks gestation, nursed naked in 90% oxygen, would obtain up to 20% of resting oxygen requirements percutaneously.
The newborn infant's skin is not a complete barrier to the absorption of externally applied agents, particularly if it is damaged, diseased, or immature. Immaturity is the most important factor that determines percutaneous absorption. Very immature infants in the early neonatal period have a poorly developed epidermis, which is readily permeable to drugs. The main consequences of percutaneous absorption are hazardous. Topically applied agents are absorbed, causing toxic systemic effects that may result in illness and even death without the cause being recognized. No drug or antiseptic agent should be applied to the premature infant's skin without consideration of the effects that might result from percutaneous absorption. On a more optimistic note, the relatively permeable skin could be an advantage to the preterm infant by providing an alternative method of drug administration. The drug theophylline for example can be absorbed and produce therapeutic blood levels for up to 3 days after a single topical application. There is a need for the development of transdermal drug delivery systems for the newborn infant similar to those currently used for therapy in adults.
The effect of alternating night and day on sleep, feeding, and weight gain in 41 healthy preterm infants was examined in a randomised controlled trial. Twenty infants from a night and day nursery, where the intensity of light and noise was reduced between 7 pm and 7 am, spent longer sleeping and less time feeding and gained more weight than 21 infants from a control nursery, where the intensity of light and noise was not reduced. Differences were significant and became apparent only after discharge home; they were still present three months after the expected date of delivery, when infants from the night and day nursery were an average of 0.5 kg heavier (p less than 0.02). These findings suggest that physical environment has an effect (either direct or indirect) on the subsequent behaviour of preterm infants and that exposure to night and day is beneficial.
Echo planar imaging (EPI) is that form of magnetic resonance imaging which provides very short image acquisition times. EPI also provides very rapid sequential imaging. The EPI method is ideal for imaging the heart and thoracic content because images are devoid of cardio-respiratory motion artefact. Previously an analysis of transectional images has been presented. This paper is concerned with the study of the heart by the use of EPI constructions in the sagittal and coronal planes. Defining connections between ventricle and great artery is of cardinal importance in paediatric cardiology. EPI constructions in the normal heart, transposition, truncus arteriosus and right heart hypoplasia are presented and discussed.
Echo planar imaging is that form of magnetic resonance imaging which gives very short image acquisition times. The method has been used to produce images of the infant heart which are free of cardiorespiratory motion artefact, despite tachypnoea and tachycardia. EPI transections of the normal heart are compared with transections in truncus arteriosus, tetralogy of Fallot, right heart hypoplasia and transposition of the great arteries. The diagnosis of the cause of cyanosis in these infants was established by the noninvasive EPI method and validation of the findings may be found in transectional postmortem analyses reported in the literature.
Urinary epidermal growth factor (EGF) excretion was studied serially in 36 newborn infants, from 26 to 40 weeks gestation, from birth to three months of age. All infants excreted EGF from birth. Excretion was significantly higher in term infants than in preterm infants at birth; in term infants excretion rose steadily in early infancy and there was a similar but delayed rise in EGF excretion by preterm infants. Urinary EGF excretion appears to be related to age from conception and birth does not influence it. There was no correlation between urinary EGF excretion and the rapid maturation of the lungs and skin which occurs in preterm infants in the early neonatal period.
Percutaneous respiration was studied in 27 newborn infants (birth weight 0.96 to 4.43 kg, gestation 27 to 40 weeks) using a closed skin cell attached to the upper abdomen into which saturated air at 37 degrees C was introduced. Gas exchange across the skin was found to be strongly related to gestational age. Term infants had lower rates of gas exchange than found across adult skin (mean O2 absorption 32.0 vs 62.0 ml/m2/hr, mean CO2 excretion 40.5 vs 86.5 ml/m2/hr). In the first few days of life infants of less than 31 weeks gestation had rates of gas exchange five to six times higher (mean O2 absorption 178.4 ml/m2/hr, mean CO2 excretion 214.8 ml/m2/hr) than those in term infants, but these fell rapidly toward term levels by 2 weeks of age. Gas exchange correlated well with skin water loss, suggesting that the epidermal barrier limits both processes. There was a linear increase in skin O2 absorption as the O2 concentration in the skin cell increased. We estimate that if in the early neonatal period an infant of less than 31 weeks gestation were nursed naked in 40% oxygen, about 13% of total resting oxygen requirements could be obtained through the skin. Under certain limited circumstances, percutaneous oxygen delivery might be clinically useful.
The possibility that placentally-transferred labetalol might cause sympathetic blockade in the newborn infant was examined by measuring systolic blood pressure, heart and respiratory rates, palmar sweating, blood glucose and the metabolic and vasomotor responses to cold stress. Measurements were made serially over the first 72 h of life in 22 term infants, 11 born to mothers treated with labetalol and 11 carefully matched controls. Infants of mothers treated with labetalol showed a mild transient hypotension which had disappeared within 24 h [mean systolic blood pressure at 2 h, 58.8 (SEM 2.4) mmHg compared with 63.3 (SEM 3.0) mmHg for controls, P less than 0.05]. There were no other significant differences between the two groups. It is concluded that labetalol does not cause clinically important sympathetic blockade in the mature newborn infant.
Two hundred very low birthweight infants were prospectively scanned to ascertain the incidence of periventricular leucomalacia (PVL) and haemorrhage. Before collection of data, clear definitions of ultrasound abnormalities believed to represent PVL and intraventricular haemorrhage were described. These referred to small and moderate intraventricular haemorrhage, paenchymal haemorrhage, and PVL, including prolonged flare (echoes in the periventricular region lasting for two weeks or more and not becoming cystic). Sixty nine infants (34%) had no abnormality on ultrasound scans. Intraventricular haemorrhage occurred in 107 babies (37 grade I and 62 grade II), and only eight infants were thought to have true parenchymal haemorrhage. Ultrasound appearances of PVL were seen in 27 infants, 19 of whom developed cysts and eight died in the precystic stage. Prolonged flare occurred in another 25 babies. Unilateral parenchymal haemorrhage occurred in four infants who subsequently developed cystic PVL in the contralateral hemisphere. Twenty one infants developed ventricular dilatation, 12 of whom had associated parenchymal lesions. Haemorrhage, PVL, and flare occurred commonly in infants of 30 weeks' gestation and below and became markedly less common in more mature infants. We believe prolonged flare represents a form of PVL, and in this study a total of 52 (26%) infants had an ultrasound appearance of periventricular leucomalacia, an incidence considerably higher than previously reported.
Serum albumin concentration was measured in 195 infants of 25 to 42 weeks' gestation during the neonatal period. Concentrations were significantly lower in preterm infants, rising from a mean of 19 g/l at 26 weeks to 31 g/l at term. There was a 15% increase in albumin concentrations in the first three weeks of life. Oedema in the early and late neonatal period was common in preterm infants but correlated poorly with hypoalbuminaemia. Measurement of serum albumin concentrations in preterm infants either routinely or because of oedema is not clinically useful.
A spray on, copolymer acrylic dressing (Op-Site) was used to limit the skin damage caused by a transcutaneous oxygen electrode and its adhesive ring. Two identical electrodes were applied to the abdominal skin of 10 preterm infants, one on untreated skin, the other after application of Op-Site. It was found that Op-Site prevented the epidermal damage (as measured by transepidermal water loss) that occurs when the adhesive ring is removed from untreated skin. It did not interfere with transcutaneous oxygen measurements; absolute values and response times were unchanged. Op-Site is therefore useful in preventing the skin trauma that occurs when transcutaneous oxygen monitoring is being performed in preterm infants below 30 weeks' gestation in the first week of life. Care must be taken, however, to prevent a build up of Op-Site--it should be applied as a single layer, allowed to dry, and removed after use.
Histological development of the epidermis was studied on skin samples from 169 infants (gestation 24-40 weeks, age up to 1 year). Gestation markedly influenced epidermal development. Before 30 weeks, the epidermis is thin, has few cell layers and a poorly formed stratum corneum, but by 34 weeks it has largely matured. Postnatal influence on epidermal development is marked in the preterm infant, so that histologically the epidermis of the most immature infant resembles that of a term infant by 2 weeks of age. These changes in histology exactly parallel the development of the barrier properties of newborn skin.
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