Radiologic Observations in Severe Neonatal Respiratory Distress Syndrome Treated with the Isolated Phospholipid Fraction of Natural Surfactant

Ten newborn babies with severe respiratory distress syndrome, all dependent on artificial ventilation, were treated via the airways with the isolated phospholipid fraction of bovine or porcine surfactant. After treatment with surfactant at a median age of 10.5h, there was in all patients a striking improvement of lung aeration in chest films, with a decrease in parenchymal fluid retention and in distension of bronchioli. These radiologic findings were associated with a dramatic improvement of oxygenation and a significant reduction of the right-to-left shunt. In spite of the rapid therapeutic response, four patients died from cerebral hemorrhage. One of the surviving patients developed bronchopulmonary dysplasia. Our findings document efficacy of this new surfactant preparation in the neonatal respiratory distress syndrome, but the long-term effects need to be further tested in randomized clinical trials.

Concentrations of copper, zinc and selenium in brain and kidney of second trimester fetuses and infants

The concentrations of copper (Cu), zinc (Zn) and selenium (Se) in the brain and kidneys of second trimester fetuses (abortion cases) and infants (deceased before three months of age) were determined. Concentrations of Cu in brain, 0.31-1.6 mg/kg wet weight, increased with age, and were, on the average, three times higher in the brains of infants than of fetuses. In kidneys, Cu concentrations ranged between 0.34 and 2.9 mg/kg, and increased with age after birth. Concentrations of Zn in the brain decreased significantly with age in the fetuses, from about 7 mg/kg at post-conceptional week 12 to less than 5 mg/kg at week 20, but increased again postnatally. In kidneys, Zn concentrations (12-37 mg/kg) increased in parallel with the increase in tissue density. Concentrations of Se in brain, 0.072-0.14 mg/kg, decreased with age in the fetuses, but increased with age postnatally. Kidney Se concentrations (0.16-0.55 mg/kg) did not change significantly with age during the fetal period, but increased about 2.5 times during the postnatal period. There was a significant association between the concentrations (on molar basis) of Zn and Cu in kidneys, but not in brain. There was no correlation between the concentrations of Cu, Zn or Se and those of mercury, cadmium and lead, previously determined in the same samples, with the exception of mercury and Se in kidneys.

Effect of extreme prematurity on renal dopamine and norepinephrine excretion during the neonatal period

Dopamine (DA), produced in proximal tubular cells, is believed to be an important intrarenal natriuretic hormone. Experimental studies have shown that the natriuretic effect of DA is less pronounced in the fetal kidney. We have evaluated renal DA and norepinephrine (NE) in the neonatal period, using urinary excretion as an indicator of renally produced/released-catecholamines. In very low-birth-weight infants (25-30 weeks gestational age) there was an increase in urinary DA (pmol/mumol urinary creatine) and NE (pmol/mumol urinary creatinine) from 1 to 13 days postnatal age, despite a decrease in sodium excretion. Urinary NE correlated with plasma NE, whereas plasma DA was undetectable. In summary, NE excretion parallels plasma levels and could reflect the general sympathoadrenal activity, whereas DA is primarily of renal origin. Renal DA and NE increase in the first 2 weeks of life in immature infants. We conclude that the catecholamine system of the human kidney undergoes maturational changes postnatally.

Endogenous nitric oxide in the upper airways of healthy newborn infants

The endogenous production of nitric oxide (NO) in the upper airways was studied in healthy newborn infants within the first minutes after delivery (N = 2) and at postnatal ages of 1 and 24 h (N = 13). Measurements were made in infants born vaginally or by cesarean section and at various times after the rupture of membranes. Gas was sampled from the nose and pharynx, and NO concentrations were determined by a fast response chemiluminescence analyzer. Sampling from the nose at a constant flow of 20 mL/min gave 0.27 +/- 0.01 parts per million (mean +/- SEM, ppm) of NO, independent of age and mode of delivery (vaginal delivery and cesarean section). Allowing NO to accumulate in the nose for 15-120 s yielded peak concentrations up to 4.6 ppm. A 30% increase was noted between 1 and 24 h of age. We conclude that nasal peak NO concentrations in the ppm range can be demonstrated in the healthy newborn infant within the first hour after birth. Consequently autoinhalation of endogenously produced upper airway NO may play a role in the adaptation of the respiratory system to postnatal life in the human.

Concentrations of mercury, cadmium and lead in brain and kidney of second trimester fetuses and infants

The concentrations of mercury (Hg), cadmium (Cd) and lead (Pb) in brain (cerebrum) and kidney during fetal (second trimester terminations or abortions, n = 20) and postnatal (infants deceased before three months of age, n = 15) development have been studied. Information on possible sources of exposure was obtained from the mothers of the fetuses, but not from those of the infants. The median concentration of Hg in the brain was 4 micrograms/ kg wet weight in both fetuses and infants (total range < or = 2-23 micrograms/kg). The concentrations of Hg in the kidneys were significantly higher than in brain, median of Hg 6 micrograms/kg (range < or = 5-34 micrograms/kg) in fetuses and 10 micrograms/kg (< or = 7-37) in infants. There was a tendency of increasing concentration of Hg in the fetal kidney, but not in the brain, with increasing number of amalgam fillings in the mothers. The concentration of Cd in the brain was less than 1 microgram/kg in most cases, both in fetuses and infants. The concentration of Cd in the kidneys was significantly higher, with a median of about 2 micrograms/kg (1-8 micrograms/kg) in both groups. There was no detectable association between tissue Cd concentrations and the smoking habits of the mothers. The concentration of Pb in brain was below 10 micrograms/kg in most cases. In the kidneys, the concentrations of Pb were significantly higher, with a median of 12 micrograms/kg in the fetuses (range < or = 6-20 micrograms/kg) and 15 micrograms/kg (< or = 9-36 micrograms/kg) in the infants. In general, the concentrations of Cd and Pb were lower than in previously reported studies.

Sodium, potassium and chloride needs in low-birth-weight infants

A review of the daily requirements of sodium, potassium and chloride in preterm infants with particular emphasis on very low-birth-weight (VLBW) infants is given against the background of our present knowledge of the homeostatic regulation of these electrolytes during early postnatal life. Particular attention has been given to the importance of balanced fluid and electrolyte homeostasis in the control of compartment volumes and tonicity. The risk of rapid changes of extracellular fluid osmolality for many organs, and particularly for the brain, has been stressed. In order to obtain an adequate sodium and fluid balance during the first postnatal weeks in preterm infants of varying gestational age, recommendations for sodium intake during the first 4-5 postnatal weeks are given.

Nosocomial calicivirus gastroenteritis in a pediatric hospital

At St. Göran's Children's Hospital (a tertiary center), we perform electron microscopy of feces in most cases of nosocomial gastroenteritis. From September 1987 through April 1992 we identified 32 episodes of calicivirus infection, 25 of which were nosocomial and, except for one outbreak, sporadic. Systematic study of the nosocomial outbreak of calicivirus gastroenteritis from November 1991 to January 1992, revealed calicivirus in the stools of 8 of 23 children with diarrhea and 0 of 10 without diarrhea. In 3 of 7 sampled after cessation of diarrhea, calicivirus excretion continued for 3 to 6 days. We found no calicivirus in 42 staff members or 9 members of infected patients' families. Nosocomial transmission of calicivirus can occur among infants.

Neonatal kidney, fluids, and electrolytes

Numerous clinical studies during the past two decades have indicated that kidney function and regulation of electrolyte and fluid balance undergo profound changes in the neonatal period. The genetic mechanisms behind these developmental changes have recently been the topic for many investigations and has led to the identification of factors, reviewed here, that seem to be of extraordinary importance for the induction of kidney differentiation and maturation. For a long time it has been debated whether immaturity of renal function might have any clinical consequences. It now seems clear that at least one aspect of renal immaturity, namely the high urinary sodium excretion in preterm infants, which often results in negative sodium balance, should be paid more attention to because it might interfere with growth. Two recent review articles discuss this issue. The profound changes in fluid and electrolyte homeostasis that occur in the neonatal period, involves most tissues. This is exemplified with some recent exciting studies on the changes in ion transport that occur in the lung around birth.

Renal function in sick, very low-birth-weight infants

Renal immaturity is pronounced in very low-birth-weight infants with a gestational age < or = 30 weeks. We attempted to elucidate if conditions requiring mechanical ventilation, including patent ductus arteriosus, might further compromise renal function due to decreased renal perfusion. Forty infants studied between 4 and 28 days of age were divided into four groups: Control with no patent ductus or mechanical ventilation (n = 8); PDA+MV, with both patent ductus and mechanical ventilation (n = 17); PDA, with patent ductus (n = 6); MV, with mechanical ventilation (n = 9). The groups PDA+MV and MV had significantly lower creatinine clearances and significantly higher fractional sodium excretions than controls. Mean arterial pressure was significantly lower in all groups compared to controls and correlated significantly with creatinine clearance (r = 0.47, p < 0.02). In conclusion, low renal function in these infants is further compromised by a patent ductus arteriosus and/or the use of mechanical ventilation.

Skin microcirculation in neonatal polycythaemia and effects of haemodilution. Interaction between haematocrit, vasomotor activity and perfusion

The cutaneous microcirculation was investigated before and 2-4 h after haemodilution in 13 newborn infants with polycythaemia. Skin microvascular perfusion was related to the haematocrit and to the presence of rhythmical changes in blood flow, reflecting vasomotor activity. The microcirculation was studied with a laser Doppler fluxmeter in a superficial microvascular bed represented by the dorsal hand skin. In five subjects, it was possible to combine laser Doppler flux measurements with microscopic quantitations of blood cell velocity in single, nailfold capillaries. In neonates less than 12 h postnatal age (n = 6), microvascular perfusion was only one-third that of the equally polycythaemic, but older infants (n = 7, p < 0.01). The higher perfusion in the older neonates with polycythaemia was associated with rhythmical variations in blood flow (3-5 cycles/min). There was no difference in skin temperature, blood pressure or heart rate between the two age groups. After haemodilution, the younger infants had developed rhythmical blood flow variations with the same characteristics as in the older group, in which the flow pattern was unchanged. In association, the laser Doppler flux had increased 304% in the younger and 73% in the older group (median values, p < 0.05 versus pretreatment values). The post-treatment change in laser Doppler flux corresponded to an increase in nailfold capillary blood cell velocity from 0.08 (0.02-0.23) mm/s prior to haemodilution to 0.21 (0.07-0.32) mm/s after treatment (n = 5, p < 0.05). Skin microcirculatory effects of neonatal polycythaemia and haemodilution vary in relation to vasomotor activity.

Respiratory insufficiency as a cause of neonatal death (with aspects on the potential need for ECMO treatment)

In order to identify children with fatal outcome in a neonatal intensive care unit in which only outborns are admitted, a retrospective study over a 10-year period was undertaken. The study was limited to respiratory disorders. The aim of the study was to identify lethal risk factors and thereby the need for improving therapeutic tools. Diagnoses, perinatal history, ventilator settings, blood gases, medical treatment, X-ray findings, head ultrasounds, echocardiograms, laboratory tests, surgical procedures and autopsy findings were evaluated. Severe respiratory insufficiency requiring mechanical ventilation was found in 777 patients and of these babies, 207 (27%) died while still on the ventilator. Fifty-eight patients were excluded for various reasons and thus 149 patients were included in the study. It is concluded that the mortality rate from respiratory insufficiency in the material studied was consistently high over the 10-year period. New therapeutic modalities, one of which is ECMO, are offered nowadays in clinical practice and may improve mortality and morbidity rates.

Renal function in very low birth weight infants: normal maturity reached during early childhood

Development of glomerular and tubular renal function is delayed in preterm infants. To study the pattern of maturation during infancy and childhood, we re-evaluated renal function in 22 very low birth weight infants--in 14 of the infants at 18 months postconceptional age (9 months corrected age) and in the remaining 8 infants at 8 years of age. The glomerular filtration rate remained lower at 9 months corrected age than in term infants of the same postconceptional age: 82 +/- 23 versus 125 +/- 18 ml/min per 1.73 m2 (p < 0.001). At 8 years of age the glomerular filtration rate did not differ from that of healthy control subjects. Effective renal plasma flow, filtration fraction, albumin excretion, maximal concentrating ability, and kidney size determined by ultrasonography were all normal at 8 years of age. We conclude that renal function, which is markedly reduced during the neonatal period in very low birth weight infants, reaches normal maturity by 8 years of age but not by 9 months corrected age.

Effects of neonatal polycythemia and hemodilution on capillary perfusion

The effects of neonatal polycythemia on nutritive capillary perfusion were investigated by a television microscopy technique. The capillary blood flow velocity in skin was measured in 12 neonates with polycythemia before and after treatment with hemodilution, and in 13 healthy control infants. The capillary blood flow velocity in the patients was 0.11 (0.02 to 0.34) mm/sec and in the healthy control infants 0.30 (0.17 to 0.44) mm/sec (p less than 0.01, median and range values). In relation to the absolute hematocrit change after treatment range, -20% to 0%), the capillary blood flow velocity increased nonlinearly (range, +733% to -14%; r = -0.98; p less than 0.001). The postnatal age was found to contribute significantly to the variation in results--the neonates with polycythemia studied during the first day of life had a very slow skin capillary circulation and responded to treatment with a more pronounced increase in capillary blood flow velocity than did the older patients. This in vivo model for capillary perfusion indicates that an insufficient microcirculation may be involved in the pathophysiology responsible for the morbidity associated with neonatal polycythemia.

An evaluation of skin capillary blood flow determinations in neonates using a computerized videophotometric method

Dynamic capillaroscopy has been shown to give valid measurements of skin capillary blood flow in adults. The aim of this investigation is to evaluate the accuracy of the method when applied to studies in newborn infants. A computerized videophotometric technique was used to measure the skin capillary blood cell velocity (CBV) and the capillary erythrocyte column diameter at 64 standardized locations in 16 nailfold capillaries in five subjects. To estimate the method's reliability, we calculated the coefficient of variation (CV = 1 SD/mean x 100%) for repeated measurements at each location. The CV for CBV determinations was found to be 3.4% (0.9-13%) and the corresponding value for capillary diameter measurements was 6.7% (0.5-12%) (median and range). Although the CBV and diameter values were found to vary along the course of the capillary, the volume flow of blood cells was assumed to be the same in simultaneously studied but different sections of the capillary. The paired CBV and diameter observations were therefore used to calculate blood cell flow values at an average of four different intracapillary locations. To estimate the method's validity, the CV for these repeated flow calculations was determined and found to be 7.5% (3.2-26%). We conclude that the age-specific characteristics in neonates, mainly a high hematocrit and short, irregular skin capillary loops, do not limit the feasibility and accuracy of videophotometric microscopy for dynamic microcirculatory studies in neonates.

Reactive hyperemia in term neonates and adults--a laser Doppler fluxmetry study of skin microcirculation

The reactivities of neonatal and adult microcirculation have been studied and compared. The cutaneous reactive hyperemia after 1 and 4 min of arterial occlusion (AO) was measured with a laser-Doppler fluxmeter in 21 healthy neonates and 10 adults. Local skin temperature, mean arterial blood pressure (MAP), and skin prick hematocrit were also determined at the same time. The magnitude of neonatal reactive hyperemia was approximately one-third that of the adult response regardless of the duration of AO. In both groups, with age-specific regressions, the hyperemic blood flow response after 4 min of AO developed more slowly in subjects with low MAP and was of low magnitude in subjects with high hematocrit values. In response to a prolongation of AO, from 1 to 4 min, the magnitude and duration of hyperemia increased significantly and similarly in both neonates and adults. We conclude that compared to adults neonates have a less pronounced ability to increase skin microcirculation in response to local ischemia. The normally low blood pressure and high hematocrit in newborn infants contribute further to this conclusion.

Electrolyte balance

The kidney is structurally and biochemically immature at birth. As a consequence, renal function is low (3;10;ll;18). Glomerular filtration rate (related to body surface area or to body weight) is approximately 25% of that in adults. The capacity of several different tubular transport systems is lower in the infant than in the adult (2;5;13;21;28). A low transporting capacity of the neonatal kidney will sometimes result in undesired losses of electrolytes, amino acids, and peptides. The capacity to concentrate urine is low (7;29), and disturbances of serum tonicity, therefore, are common. The low concentrating capacity can be attributed to renal immaturity. The capacity of the newborn fullterm as well as preterm infant to release antidiuretic hormone is normal 7;31).

Gentamicin-resistant Klebsiella spp. and Escherichia coli in a neonatal intensive care unit

A case of septicemia in a 7-day-old infant with a gentamicin-resistant strain of Klebsiella oxytoca prompted an epidemiological survey in a neonatal unit. Within a 3-month period 7 patients presented with symptomatic infection with gentamicin-resistant gram-negative bacilli. Another 3 patients were asymptomatic and only harboured the organisms in the stool. The aminoglycoside modifying enzyme ANT(2")-a was identified with a probe technique in different gram-negative species indicating the spread of a plasmid. After the replacement of gentamicin with amikacin and the adherence to proper barrier precautions the gentamicin-resistant strains disappeared from the ward.

Ovine fetal response to water deprivation: aspects on the role of vasopressin

The effect of maternal hyperosmolality as created by an acute mannitol infusion was evaluated in eight chronic sheep preparations. Fetal osmotic and haemodynamic responses were compared to those achieved during an arginine vasopressin (AVP) infusion into the fetus (approximately 400 microU/(min kg]. To assess the AVP sensitivity of the fetal kidney the urine osmolality was determined. The activity of adenylate cyclase was measured in placental cotyledons as an indicator of AVP receptors affecting water permeability. The maternal mannitol infusion induced an increase in fetal serum AVP levels from 1.18 +/- 0.25 up to 13.76 +/- 2.11 pg/ml. During the fetal AVP infusion the AVP levels were approximately 22 pg/ml, somewhat higher when given concurrently with a mannitol infusion to the ewe (peak value: 26.13 +/- 2.80 pg/ml). Fetal heart rate increased significantly during maternal hyperosmolality while this effect was blunted by exogenous AVP given to the fetus. The AVP infusion did not affect fetal or maternal serum osmolality. During the mannitol infusion fetal serum osmolality increased to peak values which were not significantly different whether or not AVP was infused into the fetus (from 298.0 +/- 0.85 to 309.0 +/- 0.90, and from 297.7 +/- 1.47 to 307.9 +/- 0.90 mosmol/kg, respectively). Similarly, there were no differences in the effect of mannitol infusion upon fetal urine osmolality with or without AVP infusion (increments: + 149.7 +/- 34.12 and + 148.7 +/- 31.30 mosmol/kg, respectively). Adenylate cyclase activity in the placenta was unchanged before and after AVP stimulation. The data suggest an unresponsiveness of placental water permeability to fetal AVP infusion. We also conclude that a maximal urine osmolality was reached already at AVP levels obtained after an osmotic maternal load whereas at AVP levels more than twice as high the cardiovascular effects were still AVP dose-dependent.

Intracranial arterial blood flow velocity and brain blood flow during hypocarbia and hypercarbia in newborn lambs: a validation of range-gated Doppler ultrasound flow velocimetry

A transfontanellar range-gated ultrasound Doppler technique for recording blood flow velocity in an artery on the base of the skull was validated in eight anesthetized newborn lambs during hypo-, normo-, and hypercarbia. Blood flow velocity was linearly related to PaCO2 from 20 to 80 mm Hg; mean blood flow velocity (Vmean) (r = 0.86, p less than 0.001), peak systolic blood flow velocity (r = 0.83, p less than 0.001), and end-diastolic blood flow velocity (r = 0.87, p less than 0.001). Vmean changed 2.0% per mm Hg of PaCO2. A linear relationship was demonstrated between brain blood flow (BBF), as determined by the microsphere method, and PaCO2 (r = 0.91, p less than 0.001), with BBF changing 3.6%/mm Hg of PaCO2. Blood flow velocity was linearly related to BBF in the PaCO2 range studied; Vmean (r = 0.89, p less than 0.001), peak systolic blood flow velocity (r = 0.87, p less than 0.001), and end-diastolic blood flow velocity (r = 0.87, p less than 0.001). However, Vmean predicted only approximately 55% of the change in BBF, which suggests a concomitant change in the cross-sectional area of the artery being studied. Despite this limitation, these data suggest that blood flow velocity, recorded by a transfontanellar range-gated Doppler technique from one of the two main arteries perfusing the brain, provides qualitative information on changes in BBF.

Capillary blood cell velocity in full-term infants as determined in skin by videophotometric microscopy

In order to study the neonatal microcirculation, the capillary hemodynamics in skin was investigated in 43 full-term infants 2-7 days after birth. The nailfold capillaries of the thumb were visualized by means of television microscopy and the capillary blood cell velocity (CBV) was videophotometrically quantified in 107 microvessels. The skin temperature, mean arterial blood pressure, and heel puncture hematocrit were measured simultaneously to evaluate any relation with the CBV. The mean CBV in all infants was 0.38 +/- 0.21 mm/s, with a range of 0.04 to 1.2 mm/s in individual capillaries. There was no correlation between CBV and skin temperature (27-33 degrees C), mean arterial blood pressure (44-68 mm Hg), or postnatal age. However, a significant correlation was found between the log CBV and the skin prick hematocrit (r = -0.64, p less than 0.001). It is concluded that the mean CBV during the 1st wk of life is not significantly different from the capillary velocity reported in adults. Normal variations in skin temperature and mean arterial blood pressure, as well as age differences 2-7 days after birth, do not significantly influence the neonatal skin capillary blood flow. However, the hematocrit is of major importance for skin capillary perfusion in the newborn infant.

Kidney function in adults born with unilateral renal agenesis or nephrectomized in childhood

We have evaluated the long-term prognosis in an unselected group of adult patients either uni-nephrectomized in childhood because of hydronephrosis or born with unilateral renal agenesis. Thirty-six patients aged 7-47 years were followed for 7-40 years. In 23 control subjects aged 20-47 years the glomerular filtration rate (GFR) and the p-aminohippuric acid clearance (CPAH) did not change significantly with age. In patients with a single kidney the size of that kidney was larger and GFR and CPAH were higher than single kidney values in control subjects. However, in patients with a single kidney since childhood the GFR and the CPAH declined slowly but significantly during the follow-up period. Significant microalbuminuria occurred in 47% of the patients with a single kidney and was more frequent with a longer follow-up period. No patient had renal insufficiency or a marked increase in arterial blood pressure. We conclude that in patients with a single kidney since childhood the long-term prognosis is good, but the late decrease in GFR and increase in albumin excretion may indicate a moderate risk for premature renal damage.

Postnatal development of renal function in very low birthweight infants

The postnatal development of renal function was compared in infants with a gestational age of 25-30 weeks, mean 27.8 weeks (GA 28), and in infants with a gestational age of 31-34 weeks, mean 32.5 weeks (GA 32). The infants were comparable with regard to postnatal course, fluid, caloric and salt intake. Observations were made during the 1st, 2nd and 4th-7th (mean 5th) postnatal weeks. From the 1st to the 5th postnatal week the creatinine clearance (CCr ml/min/1.73 m2), increased from 11 to 20 in GA 28 and from 15 to 30 in GA 32. At 2 weeks of age CCr was significantly lower in GA 28 than in GA 32. During the first week of life diuresis was lower in GA 28 than in GA 32 but thereafter was the same in both groups. We interpret this as a sign of dehydration in GA 28. Serum arginine vasopressin (S-AVP) concentrations were high in both groups at all ages. Mean urine osmolality was low (less than 300) regardless of postnatal age and S-AVP. Urinary sodium excretion was high at 1 week of age in both groups and decreased with increasing postnatal age. Na excretion was slightly higher in GA 28 than in GA 32 at 1 but not at 2 and 5 weeks. UK/UNa was below 1 in both groups during the first week of life and increased with postnatal age. Urinary aldosterone excretion was high in both GA 28 and GA 32 at all ages. Serum sodium levels were lower in GA 28 than in GA 32 at all ages.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe neonatal respiratory distress syndrome treated with the isolated phospholipid fraction of natural surfactant

Ten newborn infants (795-1680 g) with severe respiratory distress syndrome (RDS) were treated with the isolated phospholipid fraction of bovine or porcine surfactant, which was administered via the airways (dose 200 mg/kg), at a median age of 10.5 h. Before receiving surfactant, all the infants were on artificial ventilation (FiO2 0.6-1.0). Within 2 h after surfactant replacement, the arterial-to-alveolar PO2 ratio increased from 0.1 to 0.35. There was a concomitant improvement in lung aeration on the chest roentgenograms and a significant reduction in the right-to-left shunt. Four patients died of cerebral hemorrhage; two of them also had a patent ductus arteriosus. One surviving infant developed bronchopulmonary dysplasia, and another succumbed 8 months later to the sudden infant death syndrome. No antibodies against surfactant were detected in the sera of the survivors. Since our results show a significant improvement in lung function after replacement therapy, the efficacy of this new surfactant preparation should be further tested in randomized clinical trials.

Radiologic observations in severe neonatal respiratory distress syndrome treated with the isolated phospholipid fraction of natural surfactant

Ten newborn babies with severe respiratory distress syndrome, all dependent on artificial ventilation, were treated via the airways with the isolated phospholipid fraction of bovine or porcine surfactant. After treatment with surfactant at a median age of 10.5 h, there was in all patients a striking improvement of lung aeration in chest films, with a decrease in parenchymal fluid retention and in distension of bronchioli. These radiologic findings were associated with a dramatic improvement of oxygenation and a significant reduction of the right-to-left shunt. In spite of the rapid therapeutic response, four patients died from cerebral hemorrhage. One of the surviving patients developed bronchopulmonary dysplasia. Our findings document efficacy of this new surfactant preparation in the neonatal respiratory distress syndrome, but the long-term effects need to be further tested in randomized clinical trials.

Studies in renal response to various protein intakes in preterm infants

The renal effects of two diets--breast-milk and breast-milk with extra human protein (7 g/l breast-milk)--were compared in very low birth weight infants with a gestational age of 26 to 30 weeks. When the infants were given the high protein diet for one week the glomerular filtration rate (GFR) increased significantly more than when breast-milk alone was given. Sodium clearance showed a similar increase in proportion to the GFR during the two diets. The high protein diet raised the urine osmolality moderately in all individuals, while the diuresis remained unchanged. The data in the present study indicate that the function of the immature kidney is influenced by the amount of protein in the diet. However, the long-term renal effects in preterm infants maintained on a high protein intake remain unknown.

Changes in intracranial arterial blood flow velocities during surgical ligation of the patent ductus arteriosus

A combined continuous and range-gated Doppler instrument was used to assess intracranial arterial blood flow velocity changes in infants and neonates undergoing surgical ligation of the Ductus Arteriosus (DA). Continuous recordings during DA closure in six infants (3.5-10 months old), showed an abrupt increase in diastolic blood flow velocity simultaneous with an increase in systolic and diastolic arterial blood pressure. In five infants, these changes were followed by a rapid fall in systolic and diastolic blood pressure without a concomitant change in blood flow velocity, which may be secondary to a rapid fall in intracranial vascular resistance. The mean blood flow velocity increase following DA closure was 27% (8-43%) and the changes in diastolic and mean blood flow velocity were significant (p less than 0.01). In seven preterm neonates (24-28 weeks) studied before and after surgery, a mean blood flow velocity increase of 50% (14-115%) (p less than 0.01), mainly due to an increase in diastolic blood flow velocity (p less than 0.01), was recorded. These rapid intracranial hemodynamic changes during surgical DA closure should be taken into consideration when selecting techniques for DA closure.

Herpes zoster in a 2-week-old premature infant with possible congenital varicella encephalitis

This report concerns a case of neonatal herpes zoster associated with maternal gestational varicella. The child developed skin lesions at 18 days of age virologically confirmed to be varicella-zoster. The baby also had encephalitis and aspiration probably due to bulbar paralysis. Multiple small necrotic areas were found in the thalamus at post-mortem examination.

Regulation of renal water excretion in newborn full-term infants

The renal response to low (45 ml/kg) and high (73 ml/kg) fluid intake was studied during an 8-hour period in healthy 3-4-day-old full-term infants. 20 infants received low fluid (LF) intake and 15 infants received high fluid (HF) intake. HF significantly increased urine flow and significantly decreased urine osmolality but did not influence glomerular filtration rate measured as the clearance of creatinine. Serum arginine vasopressin (s-AVP) was not different in the LF and HF groups and did not correlate to urine osmolality. Urinary sodium excretion was significantly correlated to the diuresis.

CONCLUSION

Following high fluid intake full-term infants are capable to adaptively excrete larger urine volumes and more dilute urine by mechanisms independent of AVP. S-AVP appears to relate differently to the state of hydration and to urine osmolality in infants than in adults.

Role of arginine vasopressin in blood pressure control in young rats

We investigated the importance of arginine-vasopressin (AVP) for blood pressure control in young and adult rats. Most of the studies were performed on Brattleboro rats with complete diabetes insipidus (DI). In some protocols, Sprague-Dawley rats (SD) were also used. The rats were age 20-24 days (young) or 50-80 days (adult). Adult DI rats have a significantly higher mean arterial pressure (MAP) than adult SD rats. The studies were performed during normovolemia and hypovolemia. Hypovolemia was created by the rapid withdrawal of blood, 0.5-1.5% of body weight. Following bleeding 0.5% of the body weight, young DI rats had a significantly larger decrease in MAP than adult DI and young and adult SD rats. Continuous infusion of AVP (2000 pg X 100 g-1 min-1) blunted the hemorrhagic hypotension in the DI rats. In all groups of rats studied, AVP had little effect on the MAP during normovolemia. The effect of AVP (given in a bolus dose of 20 or 2000 pg X 100 g-1) on the MAP was in DI rats significantly related to the MAP immediately prior to the AVP administration. No effect on MAP was observed when the initial MAP was 105-112 mm in the young DI rats and 148-157 mm in the adult DI rats. The effect of AVP (20 pg X 100 g-1) appeared to be submaximal to maximal. In anaesthetized SD rats, the basal AVP production was higher in the young than in the adult animals. Following bleeding, serum AVP increased in both young and adult rats but the increase was significant only in the adult rats.

Glomerular tubular balance in preterm and fullterm infants

The development of glomerular and tubular function was studied in preterm and fullterm infants of varying gestational and postnatal age. The results indicate that glomerular functional development precedes tubular functional development until the 34th postmenstrual week. After the 34th week the tubular transport capacity seems to be more vulnerable than the glomerular filtration rate in states of disease. The release of a postulated renal vasoconstriction could account for the rapid changes in renal function after birth. The purpose of such a vasoconstriction could be to protect the tubules from an overload.

Postnatal control of water and electrolyte homeostasis in pre-term and full-term infants

A review is given of the progress which has been made during the last decade within the field of renal control of water and sodium homeostasis in newborn infants of varying gestational age. Both preterm and full-term infants have a low capacity for rapid excretion of a salt load. The natriuretic response improves gradually up to the age of 15 months. The capacity to excrete a load of sodium bicarbonate is higher than to excrete a load of sodium chloride. Under basal conditions preterm infants of a gestational age below 35 weeks have a higher renal sodium excretion than full-term infants. They also appear to be unable to retain sodium when in negative balance. The capacity to concentrate the urine is low in newborn infants, the maximal osmolality being only slightly above that of plasma. The concentrating capacity increases relatively fast during the first 4-6 postnatal weeks in full-term as well as in pre-term infants but does not reach the adult level until the second year. Water loaded newborn infants are able to excrete a urine with a osmolality as low as 30-50 mOsm per kg. In full-term infants free water clearance per unit filtered water is higher than in adults. Water-loaded pre-term infants with a gestational age of more than 30 weeks also have a supernormal diluting capacity.

Renal function in dogs with chronic moderate unilateral ureteral obstruction

Partial obstruction of the left ureter was created in seven dogs. Renal function was studied 3 weeks later. Total renal blood flow (RBF) and intrarenal blood flow distribution were studied using the microsphere technique. Glomerular filtration rate (GFR), effective renal plasma flow (CPAH) and the excretion of sodium and osmolar substances were determined using the clearance technique. RBF, GFR and CPAH in the hydronephrotic kidney were reduced to approximately 30% of the same parameters in the contralateral kidney. Urinary sodium excretion was consistently lower in the hydronephrotic than in the contralateral kidney. Volume expansion with isotonic saline solution revealed that this reduction of sodium excretion from the hydronephrotic kidney was out of proportion to the extent of GFR reduction. The contralateral unobstructed kidney did not compensate for this salt retention by increasing its sodium excretion.

The effect of prostaglandin inhibition on renal function in the developing anesthetized lamb

The importance of prostaglandin (PG) compounds for renal function in the developing kidney was studied by comparing renal blood flow (RBF), glomerular filtration rate (GFR) and fractional sodium (Na) excretion in control lambs and lambs treated with a PG synthesis inhibitor, indomethacin. The lambs were 1-2 and 4-6 weeks old and they were studied either during hydropenia (HP) or volume expansion (VE). Indomethacin significantly decreased Na excretion in both groups of hydropenic lambs. Indomethacin also completely blunted the natriuretic response to VE in the older lambs but had no effect on Na excretion in the volume expanded younger lambs. It is concluded that partial lack of PG inhibiting action on tubular Na transport will contribute to the poor natriuretic response to VE in neonatal lambs. Since PG will act locally rather than being blood-borne messengers, The divergent PG action in younger and older lambs might be explained by local differences in maturation of PG metabolism as well as by local differences in the maturation of PG sensitivity.

Postnatal development of renal function in pre-term and full-term infants

This study has been designed to examine the effect of gestational age (GA) on the postnatal development of renal function and has been performed in pre-term (PT) infants (GA=30-34 weeks) and in full-term (FT) infants (GA=39-41 weeks). Postnatal age has ranged from 1-35 days. From 8 hour urine samples collected after spontaneous voiding and a capillary blood sample, determinations have been made of the clearance of creatinine (CCr), the fractional excretion of beta 2-microglobulin (FE beta 2) and the fractional excretion of sodium (FENa). In some infants receiving fluid parenterally, simultaneous determinations were made of the clearance of creatinine and inulin. As judged from this study, CCr is a reliable indicator of the glomerular filtration rate (GFR). GFR was almost the same in newborn PT and FT, but from 0.3--1 week of age GFR increased significantly more rapidly in FT than in PT. From 1--5 weeks of age GFR increased at approximately the same rate in PT and FT infants. The absolute value for GFR in 3--5 weeks old infants was lower in PT than in FT. FE beta 2 was higher in PT than in FT infants during the entire first month of life and FENa was higher in PT than in FT infants during the first week of life, suggesting a glomerular tubular imbalance at least at the level of the proximal tubule in PT infants. It is concluded that different stages of maturation will alter the preconditions for the renal adaptation to extrauterine life during at least the first month of life. Therefore special attention must be paid to the limited renal function in PT during their entire first month of life.

Cytotoxic treatment in children with idiopathic nephrotic syndrome

The purpose of this retrospective study was to investigate the therapeutic value of steroids and cytotoxics in children with idiopathic nephrotic syndrome which developed during the period 1968-1977. Thirty-eight patients were followed. They were divided into three morphological groups based on renal biopsy findings, i.e., minimal changes (MCNS, n = 34), focal segmental glomerulosclerosis (FSGS, n=2) and atypical undefined changes (Undef., n=2). In the latter two groups therapy was less successful than in the MCNS-group. This study conclusively demonstrates that cytotoxic therapy is of value in prolonging the duration of the remission and increasing the responsiveness to steroids in children with MCNS.

Effect of isotonic volume expansion on glomerular filtration rate and renal hemodynamics in the developing rat kidney

Young rats (20-24 days) and adult rats (40-45 days) were studied during hydropenia and volume expansion with regard to glomerular filtration rate (GFR) and the determinants of GFR. During hydropenia, GFR and renal blood flow (RBF) were significantly lower in younger than in adult rats both in absolute terms and when related to bodyweight. Equivalent degrees of volume expansion (6% of b.wt.) resulted in a much more pronounced increase in GFR and RBF in younger than in older rats. This suggests that the high renal vascular resistance in hydropenic young rats is primarily due to vasoconstriction. The relationship between the filtration rate of superficial nephrons and the total GFR was the same in hydropenic and volume expanded rats in both age groups. The tubular stop flow pressure, the calculated hydrostatic glomerular capillary pressure and ultrafiltration pressure in the afferent part of the glomerular capillaries was slightly lower in hydropenic young rats than in hydropenic adult rats. The pressures did not rise after volume expansion. It is concluded that the marked increase in GFR in volume expanded young rats is mainly due to increased renal plasma flow.

Sodium excretion in relation to sodium intake and aldosterone excretion in newborn pre-term and full-term infants

The importance of aldosterone for the control of salt balance has been examined in pre-term infants (gestational age 28--34 weeks) and in full-term infants. The post-natal age has varied from 2--21 days. Eight-hour urinary specimens have been analysed with regard to sodium, potassium and aldosterone. The daily sodium intake has been recorded following determination of milk intake and analyses of sodium in breast milk. Due to variations of sodium content of breast milk, the daily sodium intake in pre-term infants was lower than in full-term infants during the first 10 days of life. The sodium excretion was significantly higher in pre-term infants than in full-term infants during the first six days of life. During the first week of life the sodium balance is negative in pre-term infants and positive in full-term infants. Aldosterone excretion is high during the first week of life and increases further from the 2nd to the 3rd week of life in both pre-term and full-term infants. The correlation between aldosterone excretion and urinary potassium/sodium quotient is 0.87 in full-term infants, 0.57 in pre-term infants aged 13--20 days and does not exist in pre-term infants aged 2--10 days. It is suggested that the high sodium excretion in newborn pre-term infants can in part be explained by an unresponsiveness to aldosterone at this developmental stage.

Renal sodium excretory capacity in infants under different dietary conditions

An evaluation of dietary effects on sodium (Na) homeostasis was performed in 28 healthy infants 7--13 weeks of age. Each infant received during one week an ordinary formula where either the Na and/or the protein content was increased twice. The high Na diets induced a significant elevation of the natriuretic response to an oral Na load. The response was most pronounced in those infants receiving a high Na as well as a high protein diet. The diet that was only high in protein resulted in an increased osmotic load to the kidneys but did not affect the Na excretion. The maturation of renal Na excretion thus seems to be accelerated by a high Na intake and further potentiated by a high protein intake. The Na excretory capacity was, even after the period of a high Na diet, well above the level of Na then given.

A comparative study of the response to an oral NaCl and NaHCO3 load in newborn preterm and full term infants

Previous recommendations on salt tolerance of newborn infants have mainly been based on knowledge of the capacity of newborn infants to excrete NaCl. Since tolerance to NaHCO3 can hardly be predicted from knowledge of tolerance of NaCl, a comparative study of Na+ excretion following equivalent doses of NaCl and NaHCO3 has been carried out. Forty-nine full term infants aged 0-2 days and 3-7 days were given either an oral load of NaCl or NaHCO3. Ten preterm infants (gestational age 30-35 weeks, postnatal age 2-18 days) were given both NaCl and NaHCO3 after a 2-day interval. The average urinary Na+ excretion 1-5 hr after the load was higher in all full term infants studied, but the difference was significant only in 3-to 7-day-old infants. In 7 of the 10 preterm infants the urinary Na+ excretion was higher following the NaHCO3 load than following the NaCl load. The mean difference between the tests averaged 1 mmol Na+/1.73 m2/hr and was significant. A somewhat higher daily allowance of NaHCO3 (15 mmol/kg/24 hr) than of NaCl (12 mmol/kg/24 hr) is therefore recommended.

Renal hemodynamics in the perinatal period. A study in lambs

The perinatal changes in renal hemodynamics have been studied in lambs. Eleven of the lambs were exteriorized, but maintained on placental circulation (fetal lambs). Eight of the lambs were delivered with cesarean section and studied immediately after clamping of the cord (newborn lambs). Nine lambs were delivered spontaneously and studied during the first 9 days of life. Renal blood flow (RBF) was determined by the microsphere method using a sample drawn from the iliac artery as the reference flow. The filtering capacity of the nephrons was evaluated after ferrocyanide injection and dissection of the nephrons. Total RBF did not seem to change much at birth but increased in relation to kidney weight during the first postnatal week. Clamping of the cord did, however, result in a change in intrarenal blood flow distribution, so that in the newborn lambs relatively more of the blood flow was perfusing the outer cortical region. During the first postnatal week there was a slight, but insignificant further relative increase in outer cortical blood flow. The relative increase in outer cortical blood flow at birth was accompanied by an increased frequency of filtering superficial nephrons from 22 to 77%. Practically all juxtamedullary nephrons were filtering before birth. Three days postnatally 98% of the superficial and 100% of the juxtamedullary nephrons were filtering.

Effect of arterial blood pressure reduction on renal hemodynamics in the developing lamb

The relationship between pressure and flow in the kidney has been examined in 2-9 and 31-48 day old lambs. Renal blood flow (RBF), determined by the microsphere technique, and glomerular filtration rate (GFR) were first studied under control conditions. The abdominal aorta was then constricted above the renal arteries until the pressure ranged between 60 and 70 mmHg, i.e. just below the normal autoregulatory range, and the hemodynamic recordings were repeated. During control conditions the arterial pressure was lower in the younger (93 mmHg) than in the older lambs (107 mmHg). During aortic constriction total RBF and GFR were reduced. In both age groups GFR was reduced out of proportion to RBF. The sodium excretion fell around 60% in both age groups. The fall in perfusion pressure resulted in a more pronounced blood flow reduction to the outer than to the inner cortical glomerular capillaries. This pressure-induced blood flow redistribution was found in both age groups. The consequences of the pronounced effect of reducing the perfusion pressure to 60-65 mmHg for the young lambs with their basally low arterial blood pressure are discussed.

Changes in renal hemodynamics and sodium excretion during saline infusion in lambs

The renal response to a progressive isotonic extracellular volume (ECV) expansion was studied in 13 lambs of two age groups (5-28 days and 48-57 days). Changes in renal hemodynamics induced by the ECV expansion were followed. Intrarenal blood flow was determined by the microsphere method. For determination of the glomerular filtration rate (GFR) standard clearance techniques were used. Recordings were made during control conditions and when normal saline had been infused in amounts up to 4.5% of the body weight. During the infusion there was an increase in sodium excretion both in absolute values and in relationship to GFR. The increase was, however, much less pronounced in the younger lambs. The GFR did not change significantly during saline infusion. The cortical blood flow increased only in the older lambs. As a consequence the quotient between GFR and cortical blood flow decreased in the older lambs. The possibility of a causal relationship between the fall in filtration fraction so obtained and the more pronounced natriuretic response in the older lambs is discussed. The inner to outer cortical blood flow ratio increased more in the younger lambs during saline infusion. The functional significance of an age related blood flow redistribution is, however, not clear.

Development of glomerular perfusion rate and nephron filtration rate in rats 17-60 days old

The development of filtration rate and perfusion rate in superficial nephrons has been studied in 17- to 60-day-old rats with micropuncture and microsphere techniques. Recordings have also been made of total renal blood flow (RBF), cardiac output (CO), arterial blood pressure, and hematocrit. Sincle-nephron glomerular filtration rate (SNGFR) as well as glomerular perfusion rate (GPR) and RBF described a similar developmental pattern with a slower rise from 17 to 30 days of age and a faster rise thereafter. No plateau was observed. The quotient between SNGFR and GPR was constant from at least 22 days of age. Since the hematocrit was also constant after 22 days this implies a constant filtration fraction. On the basis of those findings it is suggested that GPR is the main determinator for the development of GFR. The fraction of cardiac output perfusing the kidneys increased continuously in 17- to 60-day-old rats, suggesting that the increase in RBF and GPR is due to intrarenal factors: renal vasodilatation and increase in renal vascular volume.