Biomedical subjects

S Bevegård

Publications and source records attributed to S Bevegård.

At least 37 records · Page 2Linked to original sources

PubMed1988

Asthma from childhood to adult age. A prospective study of twenty subjects with special reference to the clinical course and pulmonary function.

Twenty young men with a mean age 24.9 years, who had moderate to severe asthma during childhood, underwent a follow-up examination of their clinical status and pulmonary function. Comparison was made with data obtained at a mean age of 10.9 years. Eight of twenty showed a clinical improvement and 12 no change in their asthma. During childhood 12 of 20 boys had been on longterm ACTH or corticosteroid treatment. In the present study no one was given systemic steroid treatment. The static lung volumes (VC, TLC, FRC RV) were within normal limits for children and adults. In spite of clinical improvement, the expiratory flow rates (FEV1, FEV%) were still significantly reduced (p less than 0.005). Thus, the clinical improvement was not accompanied by a corresponding improvement in expiratory flow rates.

Adult↗

PubMed1988

Responses to carotid sinus stimulation before and after propranolol.

The response to carotid sinus stimulation was studied in nine elderly men (mean age 67) with no history of cardiac disease, dizziness, or syncope. The response to manual carotid sinus pressure (during one of two studies) was positive (an RR interval of greater than 3s) in three men. But seven men showed positive responses after intravenous propranolol (0.1 mg/kg). Similarly, the RR interval was lengthened by greater than 10 ms/mm Hg in two men during neck suction. Neck suction produced a positive result in four men after intravenous propranolol. The detection of hypersensitivity of the carotid sinus in a high proportion of apparently healthy men, especially during beta blockade, suggests that an abnormal response to carotid sinus massage may not be a reliable indicator for pacemaker treatment.

Aged↗

PubMed1988

Evaluation of three simple physiologic tests as predictors of pregnancy-induced hypertension. A pilot study.

In order to try to find a method for predicting pregnancy-induced hypertension (PIH), the roll-over test, isometric handgrip test and cold pressor test were performed on 40 healthy pregnant women in their 29th to 31st week of pregnancy. All these three tests proved positive (rise in diastolic pressure of at least 20 mmHg) in more than 50% of the subjects. None of the women in the study developed PIH (blood pressure 140/90 or more on at least two consecutive occasions). These results indicate that none of these simple physiologic tests is of use as a predictor of PIH.

Adolescent↗

PubMed1988

Effect of exercise on catecholamines and plasma renin activity in pregnant women.

Strenuous muscular exercise is known to induce increases in plasma values of adrenalin (A) and noradrenaline (NA) and a twofold increase in plasma renin activity (PRA) in healthy men and women. The effect in pregnant women is not known. In 36 pregnant women, systolic blood pressure and plasma levels of PRA, A and NA were determined at rest, during an orthostatic test and during submaximal leg exercise on a bicycle ergometer. Eight of these women were re-examined after delivery and served as a non-pregnant control group. The pregnant women had a significantly greater increase in systolic blood pressure than the non-pregnant subjects. PRA showed a sevenfold increase during pregnancy, but exercise caused no further change in plasma values. As expected, the non-pregnant PRA values doubled during exercise. Resting values of A and NA were not altered by pregnancy. Near-maximal exercise caused a significant rise in A and NA, both in pregnant and in non-pregnant women. The results indicate that there is no activation of the sympathetic nervous system either at rest or during strenuous exercise in pregnancy and that the sensitivity of the circulatory system seems to be well adjusted to the increased activity of the renin angiotensin system during pregnancy.

Adolescent↗

PubMed1988

Posture-induced airflow limitation in asthma: relationship to plasma catecholamines and an inhaled anticholinergic agent.

Postural influence on ventilatory function was investigated in thirteen asthmatic subjects on three consecutive days starting at 10.00 am. Lung function was measured in the seated position before and after four hours lying supine. Peak expiratory flow (PEF) was measured every 0.5 h in the supine position. Blood samples for determination of plasma catecholamines were collected before, during and after lying supine. After the initial lung function testing, placebo or ipratropium bromide (0.125 mg) was inhaled. On the third day the whole trial was performed seated, without any drug, as a control experiment. On the placebo day lying supine induced an initial, rapid fall of PEF followed by a progressive decrease during the four hours. The progressive decrease in PEF was apparently caused by bronchoconstriction. Ipratropium bromide prevented this posture-induced bronchoconstriction. On the day seated there was also a tendency towards a decline of PEF though less pronounced than in the supine position on the placebo day. No significant alterations in plasma levels of catecholamines were observed. We conclude that the supine posture is a stimulus to bronchoconstriction in asthma, likely to be involved in nocturnal wheezing. Postural bronchoconstriction is not explained by lowered plasma levels of adrenaline, as has been suggested for nocturnal asthma. The results raise the question of whether cholinergic mechanisms are involved.

Acute Disease↗

PubMed1987

High vascular tone but no obliterative lesions in vibration white fingers.

To study if obliterative lesions in digital arteries are relevant as the pathogenic factor in vibration white finger, finger blood flow was measured in 15 subjects with advanced symptoms and in 15 controls by venous occlusion plethysmography before and after vasodilation. Before vasodilation, the subjects had lower temperature, blood flow, and peak blood flow after arterial occlusion in the fingers than did the controls, while venous tone was increased. In addition, after sympathicolysis, finger blood flow was lower in the study than in the control group, but there was no difference peak blood flow after arterial occlusion or in venous tone. The results indicate that the subjects have a high vascular tone causing a reduction in blood flow during submaximal flow conditions. Obliterative organic lesions in finger arteries do not seem to be present, since the "maximal" flow values of the subjects are similar to those of the controls.

Blood Flow Velocity↗

PubMed1986

Analysis of phenylephrine in plasma: initial data about the concentration-effect relationship.

A simple and sensitive assay for phenylephrine in plasma using HPLC with electrochemical detection is presented. Infusion of phenylephrine hydrochloride 0.5, 1.0, 2.0, and 4.0 micrograms X kg-1 X min-1 for 6 min at each dose level to 9 healthy subjects resulted in mean venous plasma concentrations of phenylephrine of 20, 56, 118 and 308 nM, respectively. The systolic and diastolic blood pressures were increased and the heart rate and venous plasma noradrenaline levels fell with increasing phenylephrine concentrations. There was a more than two-fold interindividual variation in the plasma concentration during infusion of the standardized doses of phenylephrine, with overlap of the concentrations achieved at the different dose levels. Estimates of the sensitivity to phenylephrine showed discrepancies within individuals when expressed as the concentration (PC20) or dose (PD20) required to increase systolic blood pressure by 20 mm Hg. Thus, evaluation of concentration-response curves should be more reliable than of dose-response curves when assessing phenylephrine sensitivity during i.v. infusions.

Adult↗

PubMed1986

Reduced platelet MAO activity during pregnancy.

The kinetics and thermolability of platelet MAO were studied in twenty-three women during and after pregnancy. The maximal velocity of the enzyme (Vmax) was significantly reduced during pregnancy, whereas the apparent, Michaelis constant (Km) was unaltered. The initial velocity of the enzyme (vo) was significantly lowered during the pregnant period compared to after delivery. However, when the enzyme activity was determined in the presence of autologous plasma, no significant difference in deaminating activity between the two occasions could be detected. This was caused by a significantly increased activating capacity of the plasma collected during the pregnant period, expressed as the ratio of MAO activity determined in the presence and absence of plasma. Moreover, pregnant women showed an increased thermal stability of the platelet MAO compared to non-pregnant women.

Adolescent↗

PubMed1983

Comparison of the protective effect of ketotifen and disodium cromoglycate on exercise-induced asthma in asthmatic boys.

Fourteen boys with a mean age of 12.2 years were studied with respect to the protective effect of ketotifen on exercise-induced asthma (EIA) in comparison with disodium cromoglycate (DSCG). All had a positive history of EIA and a post-exercise fall in FEV1 of more than 20%. A double blind cross-over technique was used with a 1 week wash-out period between the two treatment alternatives. Both drugs gave some, but not significant protection for EIA and no differences between the two active substances tested were found. Great individual differences in the response to the two drugs were noted.

Adolescent↗

PubMed1983

Carotid baroreflexes during hemodialysis.

In 9 regular hemodialysis patients, the carotid baroreceptor reflex was studied using standardized carotid sinus stimulation by neck suction. All patients were studied during predialysis conditions (recirculation), and during dialysis using dialyzate sodium concentrations of 145 and 133 mmoles/l. Baroreceptor stimulation was performed during the recirculation period and after 120-266 minutes of combined dialysis and ultrafiltration. Dialysis alone with either sodium concentration tended to decrease blood pressure. Heart rate as well as plasma renin activity increased significantly during dialysis with either procedure. In contrast to the findings in healthy subjects, heart rate was not influenced by neck suction, possibly reflecting a vagal neuropathy in uremic patients. However, carotid sinus stimulation decreased systolic pressure during recirculation to the same extent as has been found in healthy subjects. Furthermore, the blood pressure response to neck suction was enhanced during dialysis. These findings suggest that the blood pressure decrease during dialysis can not be explained by defective blood pressure control by the carotid sinus baroreceptors.

Carotid Sinus↗

PubMed1982

Transient vasodilatation in forearm on stimulation of carotid baroreceptors in man.

Carotid baroreceptor modulation of forearm vascular resistance was examined in 6 healthy subjects, each subject participating in 6 identical experimental runs. Forearm vascular resistance was calculated from simultaneous measurements of blood pressure and forearm blood flow (venous occlusion plethysmography). Carotid baroreceptor activity was modified by neck suction technique. To compare the effects of dynamic and static changes of baroreceptor activity neck suction was increased as a ramp lasting 6 s from -10 mm Hg (control) to -40 mm Hg and then maintained at this level. Measurements were started 15 s before and 9 s ('early') and 30 s ('late') after the onset of the suction ramp. Vascular resistance showed a significant (P less than 0.01) decrease during 'early' suction; but recovered partially and during 'late' suction there was no significant difference from control. The results indicate that carotid baroreceptors do modulate vascular resistance in the forearm and that the effect is more pronounced in response to dynamic than to static changes in baroreceptor input.

Adrenergic Fibers↗

PubMed1981

Circulatory effects of carotid sinus stimulation and changes in blood volume distribution in hypertensive man.

In 8 patients with moderate hypertension and 8 normotensive subjects an attempt was made to study the circulatory effects of high and low pressure baroreceptor stimulation. Intrathoracic low pressure receptors were stimulation by changes in blood volume distribution using lower body negative pressure (LBNP) and lower body positive pressure (LBPP). The carotid sinus was stimulated by sinusoidal neck suction. Blood pressure, central venous pressure, heart rate, cardiac output and forearm blood flow were recorded. During LBNP and LBPP changes in central blood volume, reflected in changes in central venous pressure, induced significantly greater changes in cardiac output and forearm blood flow in the hypertensive subjects. In both normotensive and hypertensive subjects mean arterial blood pressure was essentially unchanged during LBNP and a slight increase was found during LBPP. Heart rate and blood pressure response to stimulation of the carotid sinus decreased with increasing resting mean arterial pressure. The results suggest impairment of reflex adjustments, via arterial baroreceptor, possibly in particular to dynamic stimuli, rather than via intrathoracic "low pressure" baroreceptors in subjects with moderate hypertension.

Adult↗

PubMed1980

Two years' follow-up of asthmatic boys participating in a physical activity programme.

Eleven boys with bronchial asthma, mean age 11.2 years, particpated in a 20-month long physical activity programme. The training was performed in an ordinary indoor gymnasium for one hour twice a week. No drugs were given prior to the training sessions. Cardiorespiratory function and dimensions and maximal aerobic capacity were determined before, during and after the training period. The respiratory and circulatory dimensions increased as expected during and after the training period. The respiratory and circulatory dimensions increased as expected during the observation period and after correction for the influence of growth no changes were seen in the variables studied. Nor did the training group differ significantly in any respect from a group of nine asthmatic boys not trained. There was only a slight but not significant increase in the maximal exygen uptake and the ventilatory coefficient in the training group as compared to the non training group. After a one-week winter-camp with high exercise intensity there was a rise in the total ventilation, the ventilatory coefficient and the maximal work performed but the maximal oxygen uptake was not affected. All boys showed a very good ability to participate in the physical activity programme at approximately the same level as the physical education given at school.

Adolescent↗

PubMed1980

Ventilation and pulmonary gas exchange at rest and during exercise in boys with bronchial asthma.

During symptom-free periods pulmonary ventilation and alveolar gas exchange was determined in 14 boys with bronchial asthma during submaximal and maximal exercise. In six of these boys studies were also made at rest. At rest there was slight hyperventilation as indicated by decreased PCO2. There was also a lowering of the arterial PO2 and all boys had an increased alveolar-arterial oxygen tension difference. During exercise, there was a sharp increase in pulmonary ventilation with values similar to those encountered in trained healthy boys; there was also a tendency towards normalization of the arterial blood gases and alveolar-arterial oxygen tension difference. This indicates either more even pulmonary ventilation and better distribution of pulmonary perfusion or more even distributions of ventilation and perfusion during physical work in sitting position. Thus, boys with bronchial asthma show good respiratory adaptation to heavy exercise. One boy developed a severe asthmatic attack during exercise and, before the symptoms developed, had a dramatic fall in the arterial PO2 with an unchanged PCO2. The possibility of a sudden drop in arterial PO2 should be kept in mind when children with bronchial asthma perform physical exercise.

Adolescent↗

PubMed1979

Cardiac output and blood pressure at rest and during exercise in boys with bronchial asthma.

Cardiac output, using dye-dilution technique, and intra-arterial blood pressure at rest and during exercise on a bicycle ergometer were determined in six boys with bronchial asthma, mean age 11.9 years. Intra-arterial blood pressure was also measured in another group of eight boys with bronchial asthma. Cardiac output, stroke volume, arteriovenous oxygen difference, blood pressure and total peripheral vascular resistance at rest and during exercise up to maximal level were within the normal limits of healthy boys of the same age. At maximal exercise, cardiac output averaged 12.4 l/min, stroke volume 66 ml, systolic, diastolic and mean blood pressures 128, 81 and 107 mmHg, respectively, and total peripheral vascular resistance 10.9 mmHg/l/min. The maximal arteriovenous oxygen difference amounted to 14.1 ml/100 ml blood which is similar to that in healthy adults.

Adolescent↗

PubMed1977

Haemodynamic effects of four months' mefruside therapy in hypertensive patients.

The haemodynamic changes after 4 months' mefruside therapy in 13 patients with essential hypertension have been studied. Intraarterial BP was significantly reduced both at rest supine and during standardized leg exercise in sitting position. The reduction was caused mainly by a decrease in cardiac output in about half of the patients and mainly by a decrease in total peripheral vascular resistance in the remainder. Thus, for the total material there was no significant change in either cardiac output or total peripheral vascular resistance. At rest, however, there was a significant decrease in storke volume (p less than 0.05) and an increase in heart rate (p less than 0.05). On changing from supine to sitting position, the average systolic and diastolic pressures increased before and decreased after therapy, the differences being significant. The results indicate that the hypotensive effect of long-term saluretic therapy is accomplished by a decrease in cardiac output and/or peripheral vascular resistance, with large interindividual variations.

Adult↗

PubMed1977

Haemodynamic effects of saluretic treatment and beta-receptor blockade in patients with essential hypertension.

The long-term haemodynamic effects of treatment with mefruside alone or in combination with alprenolol have been studied in nine patients with essential hypertension. After four months of mefruside therapy alone there was a significant decrease in intraarterial BP both at rest and during standardized leg exercise. Cardiac output and calculated total peripheral vascular resistance (TPVR) showed only minor mean decreases which were not statistically significant. Stroke volume tended to decrease and heart rate to increase. After another four months' treatment with addition of alprenolol there was a further significant decrease in intraarterial BP, related mainly to a further mean decrease in cardiac output which was not statistically significant. Heart rate decreased significantly, stroke volume was not significantly changed. Compared with the pretreatment levels, combination therapy induced a substantial decrease in intraarterial BP and a significant decrease in cardiac output both at rest in supine position and during standardized leg exercise. TPVR decreased slightly both at rest and during exercise but the change was not statistically significant. The results suggest that the decrease in BP after combined therapy with mefruside and alprenolol is mainly related to a decrease in cardiac output, the changes in TPVR being not significant. The additive hypotensive effect of alprenolol seems to be related in part to blocking of the increase in sympathetic activity that was found after treatment with mefruside alone.

Adult↗

PubMed1977

The effects of four months' treatment with spironolactone on systemic blood pressure, cardiac output and plasma renin activity in hypertensive patients.

The effect of spironolactone on BP, cardiac output, plasma renin activity and urinary excretion of electrolytes has been studied in 12 hypertensive patients. After 1 month of spironolactone therapy there was a significant decrease in arterial BP. Urinary sodium excretion was significantly decreased and plasma renin activity increased. After four months of spironolactone therapy there was no further decrease in arterial BP. Cardiac output, heart rate and stroke volume were unchanged in the supine position, but the calculated total peripheral vascular resistance (TPVR) was reduced, indicating that the lower BP was mainly a result of dilatation of the resistance vessels. During exercise there was still a significant decrease in arterial BP but this was related to a decrease in both cardiac output and TPVR.

Adult↗