PubMed Health⌕ Search

Biomedical subjects

G Simbruner

Publications and source records attributed to G Simbruner.

At least 73 records · Page 4Linked to original sources
PubMed1982

The relationship of prolactin in cord blood, gestational age and respiratory compliance after birth in newborn infants.

In 29 healthy newborns (gestational age 30-41 weeks) and 7 newborns with respiratory distress syndrome (gestational age 28-31 weeks) the prolactin levels in the cord blood and respiratory compliance was measured. Prolactin was determined by radioimmunoassay, the respiratory compliance was measured with the airway occlusion technique in spontaneously breathing newborns and with injection of known volumes and measuring the airway pressure in newborns with ventilatory support. In healthy newborns prolactin and gestational age were significantly correlated (r = 0.62, p less than 0.001), while prolactin did not correlate with respiratory compliance (r = 0.22, n. s.). Comparing 5 healthy newborns and the 7 RDS infants with prolactin values below 170 ng/ml, there was no significant difference in the prolactin levels, but in the compliance values. We conclude that prolactin does not directly influence lung maturation, but is associated with gestational age.

Fetal Blood↗
PubMed1982

[Respiratory mechanics and respiratory regulation in healthy and respiratory-diseased newborn infants of different gestational ages].

The interaction of lung mechanics, peripheral lung reflexes and chemosensitivity of the respiratory center were studied in over 80 newborns. Healthy newborns (gestational age between 30 and 41 weeks) and newborns with respiratory distress syndrome (RDS) (gestational age between 29 and 40 weeks) were studied on the first day of life. Spontaneously breathing newborns were examined using the airway occlusion technique (AOT), and intubated babies using the injection technique (IT) to measure the compliance of the respiratory system (Crs), the strength of the inspiration inhibiting reflex (IIR) and inspiratory time during airway occlusion (Ti occ), and index of chemosensitivity of the respiratory center. Crs in healthy newborns increased only slightly but statistically significant (p less than 0.001) with gestational age. Crs of newborns with RDS had an overwhelming influence on their prognosis. Newborns with Crs of less than or equal to 1 developed respiratory failure and needed ventilatory support. Newborns with a Crs less than or equal to 0.5 died despite respiratory therapy. The activity of the peripheral vagally mediated reflex system also depended on the Crs. Our results indicate that the decrease in reflex activity with gestational age is not brought about by neurologic maturation but is caused by the increasing Crs. We conclude that the peripheral vagally mediated reflexes remain the same throughout life, just the boundary condition Crs, which is given by the lung mechanics, is different for premature or mature newborns and changes with age. The chemosensitivity of the respiratory center for CO2 was characterized by the inspiratory time after an expiratory occlusion (Ti occ) which is not influenced by lung mechanics. Ti occ correlated significantly with pCO2. The relation between Ti occ and pCO2 was similar for premature and mature, healthy and respiratory ill newborns. Consequently, chemosensitivity, expressed as the ratio of Ti occ and pCO2, is independent of gestational age.

Carbon Dioxide↗
PubMed1982

[Determination of serum concentrations of aminoglycosides in the monitoring of therapy in neonates. I. Gentamycin].

We studied the serum concentrations of gentamicin by radio-immuno-assay in 22 sick prematures (birth weight 1713 +/- 469 g, prenatal age 33 +/- 3 weeks, postnatal age 12 +/- 9 days) receiving 2.5 mg/kg bid. Bactericidal concentrations were present in 91% but only 50% had normal serum concentrations and gentamicin half-lives. Gentamicin half-life decreased significantly (p less than 0.01) with postnatal age but there was no statistically significant correlation between gentamicin serum concentration and gestational age or birth weight. We therefore recommend 1. gentamicin serum concentrations to be monitored routinely in therapy of prematures especially in the first week of life, 2. to expand the dosage interval up to 18 hours (which is about the threefold half-life) in prematures during the first week of life.

Gentamicins↗
PubMed1982

[A thermodynamic model to predict oxygen consumption and peripheral blood flow in the newborn infant. II. Its validity under steady-state conditions].

A thermodynamic model, which allows to predict oxygen consumption and peripheral blood flow from temperature measurements, was tested for its validity in newborn infants. This model is based on the close relation between 1) oxygen consumption and heat production and 2) between circulation and heat convection. In this model 3 temperatures on the patient, 2 temperatures in the environment and geometrical variables (weight, length) are measured and known physiological relations used to calculate oxygen consumption (VO2) and peripheral blood flow (pBF). In 15 newborns the VO2 was synchroneously determined by means of the flow-trough method and the thermomodel. The VO2 and the VO2/kg bodyweight respectively correlated significantly (p less than 0.01) with the directly measured VO2 (correlation coefficients r 0.89 and 0.66 respectively). In 12 newborns the peripheral blood flow was synchroneously determined by means of the impedance plethysmography and the thermomodel. The directly measured peripheral blood flow correlated significantly (p less than 0.001) with the peripheral heat flow (r = 0.73, 34 measurements) and with the peripheral blood flow (r = 0.86, 34 measurements) both obtained from the thermomodel. The values of VO2 and pBF obtained by direct measurement and by the thermomodel are as closely correlated as values which were obtained comparing two conventional methods. These results demonstrate the validity of the theoretical model being suitable for clinical use to continuously predict VO2 and pBF.

Humans↗
PubMed1982

[Development and disease in the newborn infant from the viewpoint of the thermodynamics of irreversible processes].

The newborn baby was considered thermodynamically as an open system in stationary state and its rate of entropy production determined. Three groups of newborns were studied: (1) healthy, premature newborns (34 weeks gestational age) at the age of 1, 7, 14, 21 and 28 days, (2) healthy, mature newborns (39 wks GA) and mature newborns with a hypoplastic-left-heart syndrome (39 wks GA), both in their first week of life. The entropy production rate was determined by using a diagnostic procedure, based on temperature measurements and a thermodynamic model. The entropy production rate (EPR) indicates the direction and stadium of development of a system. The results show, that the EPR in prematures increases during the first four postpartal weeks i. e. up to the 38th postconceptual week and then still is lower than in mature newborns. The EPR in prematures after birth develops in the same manner as the EPR of animal organisms before birth and approaches the one of newborns at term. The EPR in newborns with a lethal congenital heart disease was significantly lower (p less than 0.01) than in healthy newborns of the same age and already during the first week of life similar to the EPR of a 70 year old persons. These results support the hypothesis that the rate of entropy production could be used as an index to indicate biological, non-chronological developmental stadium and to assess the severity of a disease respectively its tendency to heat or to deteriorate. This would be especially helpful in patients with a very complex therapeutic regime.

Body Temperature Regulation↗
PubMed1981

[Congenital toxoplasmosis in two newborn infants (author's transl)].

Two newborn infants with congenital toxoplasmosis despite serological testing during pregnancy were observed at our premature and neonatal intensive care unit within a short time of one another. In one case the counter-regulatory late first test, performed only in the 26th week, was positive with a high titre. The immediately recommended treatment was not carried out. Apart from the signs of congenital generalized infection, the newborn infant already manifested chorioretinitis and encephalitis. In the second case the initially serologically-negative pregnant women became infected only during the 35th to 36th week of gestation, around the time of the third serological examination. The child was born with slight signs of general infection, but without CNS involvement. Immediate postnatal treatment resulted in complete cure. This shows that such rare cases which can no longer be detected by serological testing can be treated postnatally with good results.

Adult↗
PubMed1981

[Is the airway-occlusion-technique used in respiratory physiology hazardous for the newborn infant? (author's transl)].

The effect of the airway-occlusion-technique (AOT) on the cardiac- and respiratory frequency, respiratory compliance and pO2 was studied in 5 healthy and 7 cardio-respiratory ill newborns. During a mean study duration of 10.8 minutes (11 occlusions) none of the variables mentioned changed significantly. We conclude that the non-invasive AOT, which informs about lung mechanics and respiratory control, carries no risk for the newborn infant.

Elasticity↗
PubMed1981

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.

Blood Pressure↗
PubMed1981

Heatflux from the fetus during delivery.

A new thermodynamic model for the fetus in utero is introduced. As the fetus is warmer than the mother, heat flows from the fetus to the maternal organism (i. e. uterine muscle, vagina). This heatflux was measured during delivery. The heatflux from the fetal head was 11 +/- 1.6 Watt/m2 (mean +/- SD). It was influenced by the maternal temperature (correlations statistically significant) in two births with pathological heart rate patterns in the cardiotocogram we observed a heatflux which deviated markedly from the norm. In conclusion, heatflux measurements could yield valuable information about the fetal metabolism and circulation of the fetomaternal unit, and could be applied as a additional method for fetal monitoring.

Body Temperature↗
PubMed1981

Hormone-sensitive adenylate cyclase in glomerular cells: possible role for inflammatory diseases of the glomerulus.

Using the adenylate cyclase assay after Ross we examined hormone sensitivity of isolated glomerular cells. cAMP production was increased 1.3--1.6-fold by stimulation with isoproterenol, 1.5--1.8 times by prostaglandin E1 and 1.4--1.5 times by histamine. The isoproterenol reaction could be completely inhibited by propranolol, the histamine effect was abolished by the H2-blocking agent cimetidine. As control we applied sodium fluoride, which directly activates the catalytic adenylate cyclase unit, increasing the activity 1.8--2.7 times (depending on the method of homogenization). These findings could reflect some physiological or pathophysiological implications, which are discussed in the present report.

Adenylyl Cyclases↗
PubMed1981

Performance of neonatal ventilators: the effects of changes in resistance and compliance.

The authors tested the ability of 6 neonatal ventilators (Baby bird, Bourns BP-200, Veriflo, Bourns LS, ServoVent, SI-75) to deliver a preset tidal volume with minimal pressures when the compliance and resistance of test lung were altered. The authors also studied the effects of gas leaks from the system and the effects of PEEP. When the ventilator cycling rates exceeded 28-43/min, gas trapping occurred despite compliances and resistance appropriate for a healthy term infant. With a normal compliance and an elevated resistance, gas trapping occurred above rates of 4-6/min. Under these same conditions (normal compliance, elevated resistance), only 24-46% of the preset tidal volume was delivered. The different ventilators caused the pressure within the test lung to exceed 5, 10, and 15 cm H2O for differing amounts of time (sec)/min.

Airway Resistance↗
PubMed1981

[Prematurity risk according to prematurity risk score and postpartal morbidity of the newborn infants (author's transl)].

Risk of premature birth was evaluated retrospectively in 610 women in the first days after delivery using the prematurity risk score published by Thalhammer 1973. The calculated risk of premature birth was compared than prospectively to postpartal morbidity of the newborn infants as determined by duration of hospital stay, incidence of respiratory distress syndrome, need of artificial ventilation and mortality. A positive correlation could be found between risk of premature birth and postpartal morbidity of the newborn infants especially in small premature infants with birthweights of 2000 grams and less. The same correlation existed also in two groups of infants out of two different obstetric clinics which showed the same distribution of prenatal risks and the same prenatal care frequencies. It clearly becomes evident that infants with the same prenatal risks but good prenatal care during pregnancy had much lower hospital stays, lower respiratory distress frequencies and lower mortality rates than babies delivered from pregnancies badly cared for. These prenatal care related differences in postpartum morbidity again were much more evident in infants out of lower birth weight classes.

Birth Weight↗
PubMed1981

[A thermodynamic model to predict oxygen consumption and peripheral blood flow of the newborn infant (author's transl)].

The continuous evaluation of the oxygen consumption and peripheral blood flow is technically difficult and practically not feasible in the newborn infant. We attempted to assess these two variables by means of a thermodynamic model, where only a set of geometrical variables and a set of temperatures have to be measured. The body is represented by a central cylinder (head, trunk) and a peripheral cylinder (extremities) and the heat flux therein is described by mathematical formulas. Only steady state conditions are considered. From the heat flux "surface leads to environment" the oxygen consumption and from the heat flux "central cylinder leads to peripheral cylinder" the peripheral blood flow is derived. On the patient only one core temperature (rectum) and two skin temperatures--one on the chest and the other one on the calf--have to be measured. The validity of the model was tested in 17 healthy newborns (body weight 1,100-3,850 g) and 6 diseased newborns (body weight 1,500-3,400 g). Comparing the computed oxygen consumption to values from the literature for a similar group showed good agreement. In 7 newborns the calculated oxygen consumption correlated well (r = 0.88, p less than 0.01) with the directly and synchroneously measured oxygen consumption. Indirect proof that the model also gives a reasonable index for the peripheral blood flow was obtained by relating the computed peripheral blood flow a) to values from the literature for a similar group and b) by demonstrating the dependence of the (calculated) peripheral blood flow on the haematocrit (r = -0.58, p less than 0.01).

Humans↗
PubMed1980

[Comparison of the surface tension of the amniotic fluid with the compliance of the respiratory system of the newborn (author's transl)].

In 51 deliveries between the 27th and 41st week of gestation amniotic fluid was collected ante partum and surface tension measured with the Wilhelmy-balance. The values obtained was compared with the respiratory compliance of the newborns determined immediately post partum. A highly significant correlation (r = -0.83, p less than 0.001) was ascertained. This finding permits a precise prediction of the pulmonary function of the newborn, especially of the especially of the severity degree of a respiratory distress syndrome already by means of amniotic fluid analysis. The less significant correlation between surfactant activity in the amniotic fluid and gestational age (r = -0,48, p less than 0.01) permits the conclusion that pulmonary maturation represents a dynamic process depending upon a variety of known and unknown factors besides the duration of gestation. On the basis of the results of this study the intrauterine and extrauterine fetal risks associated with placental insufficiency can now be estimated more accurately.

Amniocentesis↗
PubMed1980

The effect of premature rupture of the membranes on the surface activity of amniotic fluid and on the pulmonary function of the newborn.

In 30 patients with rupture of the membranes at 29 to 37 weeks gestation amniotic fluid was collected immediately and within 72 h. The concentration of lung surfactant was estimated by surface tension measurements in the Wilhelmy-balance. In 19 cases the results of the first surface tension measurement predicted lung immaturity, in 17 of these surfactant concentration increased, the last surface tension measurement being consistent with complete pulmonary maturation. None of these infants developed RDS. However, the two newborn infants, in whom serial surface tension measurements had shown no increase of surfactant concentration developed symptoms of RDS. In 11 patients with apparently mature surfactant values immediately after membrane rupture, further amniotic fluid surface tension measurements showed an increase in the concentration of surface active material. The respiratory compliance was measured in 11 healthy neonates and in the two newborn with RDS. The results reflected those of surfactant concentration obtained in amniotic fluid. Premature rupture of the membranes would seem to constitute a stimulus for fetal lung maturation.

Amniotic Fluid↗
PubMed1980

[Intrapulmonary interstitial emphysema in ventilatorsy supported infants (author's transl)].

Development of intrapulmonary interstitial emphysema together with other forms of extraalveolar air collections following alveolar rupture was investigated retrospectively in 46 term and preterm newborn infants with respect to gestational age severity of pulmonary disease and mode of ventilatory assistance. Intrapulmonary interstitial emphysema was found in 31 of these 46 infants (67%). Development depended on the severity of pulmonary disease, mode of ventilatory assistance and level of inspiratory pressure. Intrapulmonary interstitial emphysema was found at an average age of 1 day (1-6 days) in 2 out of 23 infants (9%) during unassisted spontaneous breathing, in 8 out of 24 infants (33%) during CPAP and in 21 out of 26 infants (81%) during controlled ventilation. 18 out of these 31 infants (58%) additionally developed other forms of extraalveolar air collections but only in 9 from these interstitial emphysema has been found prior to other forms of extraalveolar air. Mortality rate of infants with intrapulmonary interstitial emphysema alone (10 out of 13; 77%) and infants who additionally developed other forms of extraalveolar air collections (16 out of 18; 89%) did not differ significantly. Development of intrapulmonary interstitial emphysema even in he absence of other forms of extraalveolar air collections has therefore to be judged as a severe complication in infants undergoing different forms of ventilatory assistance.

Humans↗