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Biomedical subjects

A Okken

Publications and source records attributed to A Okken.

At least 73 records · Page 4Linked to original sources
PubMed1989

Postocclusive reactive hyperaemia of cutaneous blood flow in premature newborn infants.

Reactive hyperaemia, which occurs after a period of arterial occlusion is the result of an autoregulatory mechanism, involving local factors and autonomic nerve system control. To determine this autoregulatory mechanism in cutaneous blood flow in premature newborns measured the cutaneous reactive hyperaemia response after a 1 min occlusion, using a diode laser Doppler flowmeter applied to the skin. Twenty-four infants with a gestational age ranging from 25 to 37 weeks and a postnatal age of 0.3 to 72 days were studied. The reactive hyperaemia response is described by the parameters maximal cutaneous blood flow (Vmax), the time to reach maximal flow (tmax), the time taken for blood flow to return to baseline following Vmax (t(end)) and the % increase in cutaneous blood flow above preocclusional level (overshoot). A cutaneous reactive hyperaemia response could be elicited in all infants. Following occlusion the Vmax was 2,640 +/- 1,050 mV (mean +/- SD), the tmax was 7.6 +/- 3.9 sec (mean +/- SD), the t(end) was 35.6 +/- 14.6 sec (mean +/- SD) and the overshoot was 74.6 +/- 34% (mean +/- SD). A negative correlation was found between hematocrit and tmax (r = -0.62, p less than 0.01). No influence of postconceptional age, postnatal age, skin and rectal temperature, incubator temperature, weight, and transcutaneous oxygen tension on the reactive hyperaemia parameters could be found. We conclude that reactive hyperaemia of cutaneous blood flow can be elicited in premature newborn infants irrespective of postconceptional age, and that the hematocrit is inversely related to the time to reach maximal flow after occlusion.

Age Factors↗
PubMed1989

[Obstructive disorders of the urinary tract in the unborn child].

The history of a patient with signs of urinary tract obstruction in utero is presented. After this presentation pathophysiologic, diagnostic and therapeutic aspects of prenatal detected obstructive malformations of the urinary tract are discussed. Obstructions of the fetal urinary tract may cause damage to the developing renal parenchyma, impairment of the normal lung development and fetal growth retardation. The seriousness of obstruction and the time of appearance during pregnancy determine the severity of the damage to the unborn child. Optimum management in case of prenatal detected obstructive uropathies needs good information about renal function of the fetus, the presence of other structural defects or chromosomal abnormalities and also the maturity and state of development of the lungs. Besides careful ultrasonography of the fetus invasive methods of investigation may be necessary. In case of fetal obstructive uropathy intrauterine decompression or extrauterine decompression after an induced premature delivery can be considered. However a good renal function and the absence of other severe structural or chromosomal malformations are necessary. When the gestational age has come to 32 to 34 weeks and the lungs are mature enough decompression of the urinary tract after an induced premature delivery can be done. When pregnancy is less than 32 weeks of gestational age and the lungs are immature intrauterine decompression is possible. The most used technique of intrauterine decompression so far is insertion of a percutaneous amniotic-bladder catheter. Antenatal detected obstructive abnormalities of the fetal urinary tract need optimum perinatal care besides good information and support of the parents.

Abnormalities, Multiple↗
PubMed1988

Surfactant replacement therapy in surfactant-deficient rabbits: early effects on lung function and biochemical aspects.

Lung-surfactant-deficient rabbits (n = 6) requiring artificial ventilation were subjected to a weaning-off regimen following surfactant replacement therapy. Surfactant-deficient rabbits (n = 6) that did not receive surfactant but underwent the same procedure served as controls. All surfactant-treated rabbits survived (i.e., reestablished spontaneous air breathing) whereas all the control animals died. In the surfactant-treated animals lung function improved in such a way that during the weaning period PaCO2 did not increase and the level of PaO2 remained significantly higher than in the control animals. The static lung compliance and the stability and expansion indices in vitro were significantly higher in the surfactant-treated rabbits. The lamellar body fraction of the lungs of surfactant-treated animals contained a significantly higher amount of surfactant phospholipids than those of the control animals. It is concluded that the animal model used in this study is an excellent tool for testing early effects of different surfactant preparations.

Animals↗
PubMed1988

Forehead skin blood flow in normal neonates during active and quiet sleep, measured with a diode laser Doppler instrument.

Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter with-out light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep states could be distinguished in 17 recordings. The mean skin blood flow values during active sleep were significantly higher (p less than 0.01) than those during quiet sleep, the mean increase being 28.1%. The variability of the flow signal, expressed as the coefficient of variation, changed significantly from 23.1% during active sleep to 18.2% during quiet sleep.

Forehead↗
PubMed1987

The missing pericallosal artery on sonography: a sign of agenesis of the corpus callosum in the neonatal brain?

The sonographic findings in five newborn infants with agenesis of the corpus callosum are reported. Besides abnormal shape and position of the lateral and third ventricles of the brain, it was noted that echoreflections from the pericallosal artery were missing in all infants. Normally the pericallosal artery, which follows the surface of the corpus callosum, can be easily detected in the midline sagittal scanplane on sonography through the anterior fontanelle. It is suggested that a missing pericallosal artery is an easily detectable sign of agenesis of the corpus callosum in newborn infants.

Agenesis of Corpus Callosum↗
PubMed1987

Fat absorption in preterm infants fed a taurine-enriched formula.

An adapted cow's milk infant formula without or with extra taurine (350 mumol/l) was fed to four and five infants, respectively. The infants, born after 28-32 weeks gestation, and initially fed with a starting formula for preterms, were switched to one of the two above-mentioned formulae at approximately the 16th day of life. Each infant was studied during 4 consecutive weeks. The faecal excretion of fat, energy and total bile acids was determined from 3-day stool collections each week. The addition of taurine to the infant formula neither improved the uptake of fat and energy nor changed the faecal bile acid excretion. Growth velocity was similar in both groups of infants. Based on these results there is no rationale for adding taurine to adapted cow's milk infant formula to obtain a better fat absorption.

Dietary Fats↗
PubMed1987

Reliability of sonography in non-hemorrhagic periventricular leucomalacia.

Sonographic pictures of the brain of 19 newborn infants who died at a mean age of 4.2 days after birth (range 1-23 days) were examined independently by five experienced sonographers. In all infants information on postmortem brain pathology was available. Diagnoses made by the sonographers based on the sonographic pictures were compared with the gross postmortem findings. The results of the study show that except for one infant with a subarachnoid hemorrhage all cerebral hemorrhages were diagnosed accurately by all sonographers. Non-hemorrhagic periventricular leucomalacia (PVL), however, was missed on sonography in 2 of the 3 cases. Surprisingly, PVL was diagnosed on sonography in 1 (8%) to 6 (50%) of 12 infants in which postmortem examination of the brain revealed no PVL. It is concluded that non-hemorrhagic PVL cannot be diagnosed accurately using sonography in the first days of life, if a 5 MHz transducer is used.

Diagnostic Errors↗
PubMed1986

Persistent low plasma vitamin E levels in premature infants surviving respiratory distress syndrome.

Plasma vitamin E levels were determined serially in preterm infants surviving respiratory distress syndrome (RDS) and in premature infants without RDS (control). Vitamin E intakes of the RDS and control infant group were not significantly different. The results of the study show that preterm infants surviving RDS have a persistent low plasma vitamin E level throughout the first 8 weeks of life. In contrast, in premature infants without RDS the plasma vitamin E level gradually increases to the adult level throughout the first 8 weeks of life. It is concluded that data on plasma vitamin E levels in premature infants with and without RDS should not be pooled together to obtain reference values. It is further suggested that premature infants with RDS might need more supplemental vitamin E than premature infants without RDS.

Humans↗
PubMed1986

Body composition at birth of growth-retarded newborn infants demonstrating catch-up growth in the first year of life.

Total body, extracellular, and intracellular water volume and solids, determined at birth in a group of newborn infants small for date (n = 10) who demonstrated catch-up growth in the first year of life, were compared to similar measurements in newborn infants appropriate for date (n = 11). No significant differences with regard to body water compartment volumes and solids could be found between the 2 groups. It is concluded that intrauterine growth retardation in infants who are capable of catching up in growth after birth is the result of a proportional reduction of the daily increments in fetal solids and body water.

Body Composition↗
PubMed1985

Composition of postnatal weight loss and subsequent weight gain in small for dates newborn infants.

Using a sucrose and deuterium oxide dilution technique body water compartments and solids were serially determined in small for dates newborn infants at birth, at the moment of maximum postnatal weight loss and on recovery of birth weight. Compositions of weight loss and subsequent weight gain were calculated from the differences in body water compartments and solids between the first and the second and the second and the third study, respectively. Birth weight of the infants was 1.55 +/- 0.46 kg (mean +/- SD) (N = 7), gestational age was 35.7 +/- 3.1 weeks. Results show that despite changes in extra- and intracellular water volumes during weight loss, total body water volume and solids per unit of body weight remained remarkably constant throughout the study. Compositions of weight loss and subsequent weight gain were similar to body composition. This suggests that in small for dates newborn infants postnatal weight loss is the result of catabolism rather than dehydration and subsequent weight gain is the result of growth rather than rehydration.

Body Fluid Compartments↗
PubMed1982

Effects of forced convection of heated air on insensible water loss and heat loss in preterm infants in incubators.

To assess the effect of forced convection of heated air exchange in preterm infants in conventional incubators, we measured insensible water loss and total heat loss in preterm infants in a conventional forced convection incubator (air velocity 15 to 25 cm/second) and in a specially constructed still-air incubator (air velocity 0 to 2 cm/second) at equal operative temperature and humidity. Under the forced conditions, insensible water loss in the preterm infants increased by a mean 52% from 1.04 +/- 0.24 (mean +/- SD) to 1.58 +/- 0.51 ml/kg/hour (P less than 0.001). The ensuing increase in evaporative heat loss was partly reflected in the small but significant increase in total heat loss from 1.65 +/- 0.47 to 1.80 +/- 0.44 kcal/kg/hour (P less than 0.02). In the forced convection incubator, the increased evaporative heat loss in preterm infants was apparently partly compensated by a decreased nonevaporative heat loss. If reduction of insensible water loss is required, preterm infants should not be subjected to forced convection in incubators.

Air↗