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Biomedical subjects

U Freyschuss

Publications and source records attributed to U Freyschuss.

At least 37 records · Page 2Linked to original sources
PubMed1988

Cardiovascular and sympathoadrenal responses to mental stress: influence of beta-blockade.

Cardiovascular, sympathoadrenal, and subjective responses to mental stress induced by a color-word conflict test (CWT) were studied in 30 healthy males before and after intravenous administration of either placebo, beta 1-blockade by metoprolol (0.15 mg/kg), or nonselective beta-blockade by propranolol (0.15 mg/kg). CWT responses were reproducible. Mean arterial pressure increased by 20%. A mainly heart rate-dependent 65% increase in cardiac output (thermodilution) was associated with 25% decreases of both systemic (SVR) and calf vascular (CVR) resistances. Arterial plasma epinephrine (Epi) was doubled, and norepinephrine (NE) increased by 50%. Self-evaluated stress score correlated positively with changes in cardiac output and inversely with changes in SVR during CWT. Both metoprolol and propranolol halved heart rate responses; whereas increases in mean arterial pressure, Epi, and NE were uninfluenced. Metoprolol reduced the increase in stroke volume, and propranolol abolished it. SVR and CVR responses were attenuated by metoprolol and abolished by propranolol. The results suggest that mental stress accelerates the heart through neurogenic mechanisms and that peripheral vasodilatation is achieved through the concerted actions of reduced vasoconstrictor activity and elevated circulating Epi.

Adult↗
PubMed1988

Cardiovascular function and arterial blood gases during sham dialysis in healthy man.

Cardiovascular function and alveolar gas exchange were studied in healthy subjects undergoing sham dialysis (SHD)--i.e. the circulation of blood through a cuprophane dialyzer with the dialysate compartment closed to avoid diffusion and convective transport of fluid and solutes. The blood-membrane contact induced complement activation (rise in C3d) and transient leukopenia, as described during clinical hemodialysis. PaO2, PaCO2 and calculated oxygen uptake remained unchanged. Heart rate, cardiac index (thermodilution), systemic vascular resistance index and brachial and pulmonary arterial blood pressures did not change significantly during 150 min of SHD (n = 8). In 12 subjects, in whom more frequent measurements were made during the first 30 min of SHD, pulmonary arterial systolic and diastolic blood pressures decreased significantly while the dialyzer and the tubing set filled with blood, and pulmonary arterial mean blood pressure did not change significantly. Pulmonary capillary wedge pressure fell during the filling phase, but did not change significantly during SHD; pulmonary vascular resistance index remained unchanged. We conclude that in nonuremic subjects sham dialysis with a cuprophane dialyzer does not result in hypoxemia, pulmonary vascular constriction and pulmonary hypertension, in spite of complement activation and marked leukopenia.

Acid-Base Equilibrium↗
PubMed1988

Cardiovascular function and arterial blood gases during isolated ultrafiltration in healthy man.

In order to recognize possible cardiovascular signs of underhydration during isolated ultrafiltration (IUF), we have studied the physiological hemodynamic adaptation to IUF in healthy man both above and below normohydration. In 7 subjects IUF was performed with the subjects in a normohydrated state at the start of IUF. In 8 subjects the IUF was preceded by a 1-hour infusion of Ringer solution equal to 3% of body weight. By invasive techniques, cardiac index (thermodilution), stroke index, heart rate, brachial and pulmonary arterial blood pressures, systemic vascular resistance index, central blood temperature, PaO2 and PaCO2 were measured. Calf vascular resistance was assessed by venous occlusion plethysmography. A recirculation period of 30 min was followed by IUF in both study groups. During IUF with overhydration and normohydration at the start of IUF, cardiac output fell because of a decline in stroke volume and an unchanged heart rate. Blood pressure remained constant because of systemic vascular constriction. PaO2 and PaCO2 remained unchanged. IUF in healthy man is mainly characterized by vascular constriction and an unchanged heart rate. Thus, the cardiovascular adaptation to ultrafiltration was the same whether or not ultrafiltration was performed at overhydration or normohydration at the start of ultrafiltration. Therefore, it is unlikely that monitoring of heart rate or noninvasive recording of blood pressure can predict whether a subject is becoming underhydrated during isolated ultrafiltration. The adaptation to IUF is similar to that observed during the treatment of uremic patients without complications.

Blood Gas Analysis↗
PubMed1988

Effects of antenatal hydrocortisone on tidal volumes in spontaneously breathing preterm newborn rabbits. Possible mediation by adrenal catecholamines.

Rabbit fetuses were injected on day 26 of gestation with hydrocortisone (2 mg) and delivered by hysterotomy 2 days later. The animals were tracheotomized at birth, and tidal volumes and esophageal pressures were recorded during spontaneous ventilation at standardized intervals from the first breath to the age of 2 h. In a subgroup of animals, the catecholamine content was measured in the adrenal glands. In comparison with littermate controls, tidal volumes were enlarged in hydrocortisone-treated neonates at the first breath and 60 min after birth; however, this effect was associated with an increased incidence of intra-alveolar hemorrhage. Hydrocortisone-treated animals also had a significantly increased adrenal content of adrenaline. Our data confirm a modest beneficial effect of antenatal hydrocortisone treatment on the fetal lung and suggest that this might in part be mediated by adrenal catecholamines. Stimulation of beta-adrenergic receptors could thus potentiate the effect induced by direct influence of glucocorticoids on fetal lung maturation.

Adrenal Glands↗
PubMed1987

Exercise-induced changes in renal function and their relation to plasma noradrenaline in insulin-dependent diabetic children and adolescents.

Exercise-induced changes in renal haemodynamics, water homoeostasis, urinary albumin excretion and their possible relation to plasma noradrenaline were studied in seven insulin-dependent diabetic children and adolescents without signs of autonomic or somatic neuropathy. Six age-matched clinically healthy patients in remission from the minimal change nephrotic syndrome served as controls. The diabetic patients had a higher glomerular filtration rate and effective renal plasma flow and a lower venous plasma noradrenaline level in the basal state. They also had a higher systolic blood pressure compared with the controls. During exercise the diabetic patients showed a less marked reduction in glomerular filtration rate and urinary flow and a greater increase in filtration fraction. Their heart rate increase during exercise was lower. An inverse correlation between the percentage changes in noradrenaline and glomerular filtration rate during exercise was noted solely in the diabetic patients. They also showed a less marked increase in the ratio between potassium and sodium clearances during and 20 min after exercise. Albumin excretion did not differ between the two groups. We suggest that the sympatho-adrenergic effects of exercise on heart rate, renal haemodynamics and water homoeostasis are blunted in our diabetic patients. Hence, signs of impaired sympathetic activity might be disclosed in young diabetic patients with a disease of fairly short duration.

Adolescent↗
PubMed1987

Relation between clinical and roentgenological scores and measures of lung function in cystic fibrosis, with special reference to pulmonary Xenon133 elimination.

Regional lung function (RLF) with Xenon133 was investigated in 40 patients with cystic fibrosis (CF) aged 5-28 years (mean 13) at 1-5 occasions during a 3-year period. The RLF was determined with a 4-collimator system and evaluated with a score based on the following parameters: (1) time of elimination of injected isotope and (2) of inhaled isotope, (3) regional ventilation, (4) regional perfusion and (5) ventilation-perfusion ratios. The results were related to spirometry, X-ray score (according to a modification of Chrispin and Norman) and clinical score (according to Shwachman and excluding X-ray), which were all assessed in the same day. RLF correlated to clinical (P less than 0.01) and radiological score (P less than 0.01) and to residual volume (P less than 0.001) and the ratio between one second forced expiratory volume to vital capacity (FEV%) (P less than 0.01), but much higher correlations were found between X-ray score, clinical score and different spirometric variables. We therefore conclude that RLF can be used in patients too young to cooperate in spirometry but that it is of less clinical value in older patients with CF.

Adolescent↗
PubMed1987

Cardiovascular function and alveolar gas exchange during isovolemic hemodialysis with acetate in healthy man.

In order to elucidate the hemodynamic responses and alveolar gas exchange during isovolemic hemodialysis (IHD), without the influence of the uremic state and its complications, 7 healthy men underwent IHD. The dialysate contained acetate (40 mmol/l) and the sodium concentration was adjusted to the individual's predetermined plasma sodium concentration. By invasive techniques cardiac index (thermodilution), stroke index, heart rate, brachial and pulmonary arterial blood pressures, systemic vascular resistance index, central blood temperature, PaO2 and PaCO2 were measured. Calf vascular resistance was assessed by venous occlusion plethysmography. Plasma acetate was determined. A recirculation period of 30 min was followed by 120 min of IHD. During IHD plasma acetate increased to 2.51 +/- 0.30 mmol/l. Acetate provoked vascular dilatation, which was compensated for by a heart rate-dependent increase in cardiac index. Brachial arterial blood pressure and stroke index remained unchanged. PaCO2 and plasma bicarbonate decreased significantly, PaO2 tended to decrease and blood pH were unchanged. Thus, IHD with acetate in healthy man is mainly characterized by vasodilatation, but no cardiodepressive effects or marked hypoxemia. The adaptation to IHD is similar to that observed during treatment of uremic patients without complications.

Acetates↗
PubMed1986

Cardiovascular and metabolic responses to low dose adrenaline infusion: an invasive study in humans.

Cardiovascular and metabolic responses to intravenous infusions of adrenaline (ADR), which raised arterial plasma ADR in a stepwise fashion from 0.3 to 1.3, 2.3 and 6.0 nmol/l, were studied in 11 healthy volunteers. ADR evoked marked and concentration-dependent increases in stroke volume and cardiac output (thermodilution), as well as decreases in the vascular resistances of the systemic circulation, calf and adipose tissue. These changes were significant from 1.3 nmol/l ADR. Less marked effects were found on blood pressure and heart rate. Significant arterial ADR concentration-effect relationships were found for cyclic AMP, glycerol, glucose, lactate and noradrenaline, but not for insulin. Cyclic AMP and glycerol were significantly elevated at 1.3, glucose at 2.3, but lactate not below 6.0 nmol/l ADR. Increases in adipose tissue blood flow and arterial glycerol levels were correlated (P less than 0.001), suggesting a metabolic component in the blood flow response of adipose tissue. Invasive haemodynamic measurements revealed that ADR at arterial concentrations within the lower physiological range had considerable effects on cardiac output and vascular resistances, despite moderate changes in the conventional non-invasive haemodynamic variables blood pressure and heart rate. ADR elicited clear-cut responses at arterial plasma concentrations attained during various kinds of mild to moderate stress.

Adult↗
PubMed1986

Working capacity and pulmonary gas exchange in children with exercise-induced asthma.

Sixteen children aged 10.1-14.3 years with a history of exercise-induced asthma (EIA) were evaluated as to their working capacity both during a maximal exercise test and during submaximal exercise. During submaximal exercise ventilation and alveolar gas exchange were measured. Working capacity was normal with respect to the oxygen uptake and to the maximal load. Arterial blood gases were normal before exercise but PaO2 decreased (p less than 0.01) during the submaximal exercise test. The values were, however, still within the normal limits in all but two of the children. The flow-volume data showed bronchial obstruction in the resting state, before exercise, with lower values of MEF50 and MEF25 (p less than 0.01) than in healthy children. Following exercise, 14 of the 16 children developed clinical symptoms of asthma with increased impairment of the flow-volume curves. Most of them recovered from asthmatic symptoms within 30 min. Flow-volume curves were found to be a sensitive measurement of bronchial obstruction during the symptom-free phase and during EIA although with larger individual variations than FEV1.

Adolescent↗
PubMed1986

Physical activity and self treatment in cystic fibrosis.

A programme of increased physical activity and self treatment based on the forced expiration technique was introduced to 14 adolescent patients with cystic fibrosis, diagnosed since infancy or early childhood, who had gastrointestinal and pulmonary symptoms. Twelve patients who fulfilled the one year programme had unchanged clinical conditions, pulmonary function tests, and chest x ray films. There was a significant improvement in oxygen pressure correlated to the period of increased physical activity. Other blood gas variables, including pH, standard bicarbonate, and base excess, also indicated significant changes, mainly during exercise. The study shows that daily physical activity improves the pulmonary gas exchange and that self treatment combined with physical activity is as efficient as conventional physiotherapy.

Adolescent↗
PubMed1985

Histamine-induced asthma in children: effects on the ventilation-perfusion relationship.

Asthma was provoked by histamine inhalation in five children in order to study the hypoxaemia that might ensue and the underlying ventilation-perfusion (VA/Q) mismatching. The distribution of the VA/Q ratios was measured by a multiple inert gas technique before the provocation, during the asthmatic attack and after salbutamol inhalation. All children displayed a unimodal distribution of ventilation and perfusion under baseline conditions. During asthma they all developed a bimodal distribution, one mode lying within normal VA/Q regions but with increased perfusion to regions with VA/Q ratios of 0.1-1, which correlated with the observed hypoxaemia; the other mode was centered on a VA/Q ratio of approximately 10 and the magnitude of this mode correlated with FEV1 in percent of the predicted value. Salbutamol improved the VA/Q distribution and restored the blood gases to normal. We hypothesize that histamine-induced asthma causes a state of hyperinflation which compromises regional ventilation and blood flow, resulting in a VA/Q mismatching with one normal and one high VA/Q mode, and hypoxaemia.

Adolescent↗
PubMed1985

Effects of blood-dialyser interaction (sham-dialysis) on haemodynamics and oxygen tension in healthy man.

To evaluate the normal haemodynamic and respiratory responses to blood-membrane contact sham-dialysis, i.e. with blood flowing through a dialyser but without dialysate and ultrafiltration, was performed on healthy young men during 150 minutes. Heart rate, cardiac output, arterial blood pressure and pulmonary arterial blood pressure (continuously recorded during the initial 30 minutes) did not change significantly. The white blood cell count fell markedly to a minimum after 20 minutes of blood-membrane contact, then returning to above the baseline values, but PaO2 did not change significantly.

Adult↗
PubMed1984

Cardiac output and blood pressure in asthmatic children before and during induced asthma.

The acute circulatory effects of asthma have been studied in two groups of children, having an average age of 13.2 and 14.7 years, respectively. Asthma was provoked by exercise (EIA group) and histamine inhalation (HIA group). The latter group was also studied after subsequent inhalation of a beta 2 receptor agonist. Cardiac output was measured by dye dilution and intraarterial blood pressure was recorded. During attacks of asthma cardiac output and heart rate increased in both groups (p less than 0.05). The stroke volume decreased in the EIA group (p less than 0.01) but remained unchanged in the HIA group. The systemic vascular resistance (SVR) did not change. After salbutamol inhalation, the cardiac output and stroke volume increased and the SVR decreased (all p less than 0.05). The hemodynamic response during exercise was normal. Thus asthmatic children have normal cardiovascular function during moderate asthma. The decrease in stroke volume in the EIA group depended presumably on the preceding exercise test. The response to the beta 2-stimulation was similar to that seen in healthy adults.

Adolescent↗
PubMed1984

Lung function after repair of congenital diaphragmatic hernia.

To study lung development after repair of congenital diaphragmatic hernia 20 patients operated on between 1960 and 1976 were followed-up at 6-22 years of age. All had had an uneventful postoperative course, had no concomitant disease and were subjectively well with an ordinary physiological performance. The investigation showed a mean increase of residual volume by one third of predicted normal values. Fractional perfusion and ventilation were reduced by 20% on the hernia side compared with the contralateral side. Functional impairment owing to pulmonary hypoplasia was ruled out by the existence of a normal working capacity and maintenance of a normal alveolar gas exchange during exercise on a high work load.

Child, Preschool↗
PubMed1984

Comparison of plasma clearances of polyfructosan and 51Cr-EDTA in children.

Plasma clearances of polyfructosan and 51Cr-EDTA were determined in 38 children with renal diseases and in five healthy children in order to compare the values for the glomerular filtration rate (GFR) obtained by single injection procedures. Both one-compartment (Cr-EDTA-1) and two-compartment (Cr-EDTA-2) analyses were made of the isotope decay curve. The children were divided into two age groups: (a) 24 children below 6 years, and (b) 19 children between 8 and 16 years of age. In both groups Cr-EDTA-1 GFR and Cr-EDTA-2 GFR correlated significantly with polyfructosan GFR. The correlation coefficients, however, were somewhat lower in the younger (r = 0.74, r = 0.73) than in the older children (r = 0.91, r = 0.93). There were no significant differences between simultaneously obtained polyfructosan GFR and Cr-EDTA-2 GFR based on paired observations while Cr-EDTA-1 GFR was somewhat higher (16%) than the simultaneously obtained polyfructosan GFR. We conclude that estimates of GFR from polyfructosan and Cr-EDTA clearances based on two compartment analyses and single injection procedures are interchangeable.

Adolescent↗
PubMed1984

Ventilation-perfusion relationships during exercise-induced asthma in children.

In order to elucidate the mechanisms underlying the hypoxemia associated with exercise-induced asthma (EIA), ventilation-perfusion (VA/Q) relationships were investigated in 11 children with a history of EIA. A virtually continuous distribution of VA/Q ratios was measured by the multiple inert gas technique with the children at rest before and after an exercise test. All children displayed a unimodal distribution before the test. In 4 of the children, the exercise test did not provoke asthma, and the unimodal (VA/Q) distribution was maintained. Of the 7 children who developed asthma, 6 displayed a bimodal distribution. One mode fell within normal VA/Q regions but with increased perfusion to regions with VA/Q ratios of 0.1 to 1, which correlated well to the hypoxemia noted during asthma. The other mode fell within regions with high VA/Q ratios, and the magnitude of the mode correlated to the reduction in FEV1 and PaO2. No one had a shunt or a clearly low VA/Q mode (VA/Q less than 0.1). We hypothesize that the high VA/Q was caused by increased intrathoracic pressure impeding regional blood flow.

Adolescent↗
PubMed1984

Differentiated sympathetic activation during mental stress evoked by the Stroop test.

Sympatho-adrenal and hemodynamic responses to mental stress induced by Stroop's color word test (CWT) were examined in 12 healthy volunteers. CWT increased heart rate and blood pressures by 28 beats/min and 29/14 mmHg, on the average. The pressor response was caused by an increase in cardiac output (from 6.3 +/- 0.3 to 10.9 +/- 0.6 l/min, p less than 0.001), since systemic vascular resistance was reduced by approximately 30% during CWT. Calf vascular resistance (mainly muscle) was also reduced. At rest there was a net production of NA and a net removal of adrenaline (ADR) in the forearm tissues. About 45% of the NA in antecubital venous plasma appeared to be derived from the forearm tissues. During CWT arterial NA increased (from 1.53 +/- 0.20 to 2.13 +/- 0.15 nM, p less than 0.001), but antecubital venous NA levels remained unchanged. There was removal of ADR (about 19%) and a calculated production of NA by the lungs at rest, both of which disappeared during stress. CWT caused a "defence reaction"-like hemodynamic response with cardiac activation, but unchanged or reduced peripheral sympathetic nerve activity. This explains the lack of increase in antecubital venous NA, which is markedly influenced by sympathetic activity in the forearm tissues. Arterial plasma catecholamine measurements provide better information concerning sympatho-adrenal activity in the body as a whole than do peripheral venous measurements. Regional sympathetic activity is preferably studied by NA outflow determinations from the target organs.

Adult↗