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Biomedical subjects

O Thulesius

Publications and source records attributed to O Thulesius.

At least 37 records · Page 2Linked to original sources
PubMed1997

Gallbladder motility in laparoscopic cholecystectomy specimens.

In vitro contractility of human and sheep gallbladders to cholinergic stimulation with carbachol and the effects of indomethacin on abnormal rhythmic activity were studied. Once hundred and thirty-two gallbladders were obtained at laparoscopic cholecystectomy, 38 from patients with acute and 94 with chronic cholecystitis. In addition, 27 specimens of sheep gallbladders served as controls. Fundal preparations from patients with cholecystitis exhibit hypocontractility: no response in 72% or in the remainder a significantly reduced maximal contraction to carbachol. Regionally graded motor responses favoring propulsion of bile were abnormal in 44% of the gallbladders studied with more forceful contractions of the duct compared to the fundus. Abnormal early rhythmic activity (ERA) of fundal preparations was only detected in gallbladders of patients (in 33%) but never in controls. In 80% of these, ERA was blocked or reduced by indomethacin which can be interpreted as evidence for a prostaglandin-mediated inflammatory response. We conclude that gallbladder motility in cholelithiasis secondary to muscarinic stimulation is reduced and regionally graded motor responses favoring bile expulsion are impaired. ERA can be blocked by indomethacin.

Acute Disease↗
PubMed1996

Valvular function of peripheral veins after hyperemic dilation.

PURPOSE: We wanted to answer the question of whether physiological dilation of normal extremity veins can induce temporary valvular leakage and reflux. METHODS: Directional flow was recorded in 22 forearm and popliteal veins by Doppler duplex scanning after distal compression. Reflux was assessed by valve closure time and calculation of a "reflux index," the ratio of backward to forward flow areas. RESULTS: Hyperemia and enhanced flow did not increase but lowered reflux. During control conditions the mean reflux ratio (backward/forward flow area) of 21 veins was 0.058 and decrease to 0.028 (p < 0.05). Reflux was slightly longer in patients in the erect position in the popliteal vein, compared to forearm veins (with the patients in the sitting position). Significantly increased reflux occurred during hyperemia in only one deep forearm vein (valve closure time 0.92 seconds). CONCLUSIONS: Most veins of the upper (forearm) and lower extremity (popliteal vein) were competent even after a maneuver that induced venodilation and an increase in blood flow (exercise hyperemia or postocclusion reactive hyperemia). Veins with an inherent valvular weakness can be identified by a hyperemia test with duplex flow analysis.

Adolescent↗
PubMed1996

Cardiac output and blood pressure during active and passive standing.

The present study compared the haemodynamic pattern of active and passive standing. We used non-invasive techniques with beat-to-beat evaluation of blood pressure, heart rate and stroke volume. Seven healthy subjects, aged 24-41 (mean 30) years were examined. Finger blood pressure was continuously recorded by volume clamp technique (Finapres), and simultaneous beat-to-beat beat stroke volume was obtained, using an ultrasound Doppler technique, from the product of the valvular area and the aortic flow velocity time integral in the ascending aorta from the suprasternal notch. Measurements were performed at rest, during active standing and following passive tilt (60 degrees). Active standing caused a transient but greater reduction of blood pressure and a higher increase of heart rate than passive tilt during the first 30s (delta mean blood pressure: -39 +/- 10 vs. -16 +/- 7 mmHg, delta heart rate: 35 +/- 8 vs. 12 +/- 7 beats m-1 (active standing vs. passive tilt; P < 0.01). There was a significantly larger increase in cardiac output during active standing (37 +/- 24 vs. 0 +/- 15%, P < 0.01) and a more marked decrease in total peripheral resistance (-58 +/- 11 vs. -16 +/- 17%, P < 0.01). A precipitous rise in intra-abdominal pressure (43 +/- 22 mmHg) could be observed upon rising only in active standing. This was interpreted as an indication of translocation of blood to the thorax. There was no significant difference in haemodynamic changes during the later stage of standing (1-7 min) between both manoeuvres. These results suggest that active standing causes a marked blood pressure reduction in the initial phase which seems to reflect systemic vasodilatation caused by activation of cardiopulmonary baroreflexes, probably due to a rapid shift of blood from the splanchnic vessels in addition to the shift from muscular vessels associated with abdominal and calf muscle contraction. Moreover, the ultrasound Doppler technique was found to be a more adequate method for rapid beat-to-beat evaluation of cardiac output during orthostatic manoeuvres.

Abdomen↗
PubMed1996

Cardiovascular effects of dobutamine stress testing in women with suspected coronary artery disease.

OBJECTIVE: To investigate the central and peripheral haemodynamic response to dobutamine stress testing in women with suspected ischaemic heart disease and to seek an explanation for the hypotension phenomenon. DESIGN: 18 women aged 54-73 years were investigated with Doppler echocardiography and venous occlusion plethysmography during intravenous infusion of dobutamine 5-10 d after an episode of unstable angina. RESULTS: An average peak dose of 33 (SD 9.7) micrograms/kg/min was given. Heart rate and cardiac output increased by 49% and 59%, respectively (P < 0.001). Total and leg peripheral vascular resistance decreased by 44% and 26%, respectively (P < 0.001). Four patients developed hypotension (decrease in systolic blood pressure > 10 mm Hg), one of whom had a paradoxical bradycardia and two a low increase in cardiac output. Patients with hypotension had a more pronounced decrease in total peripheral vascular resistance but a similar change in leg peripheral vascular resistance compared with patients without hypotension. CONCLUSIONS: Dobutamine infusion leads to marked peripheral vasodilatation and an increase in cardiac output. Some patients experience hypotension during the test for reasons which include paradoxical vasovagal reactions and diminished capacity for adequate increase in cardiac output. There is also a disparity between the pattern of total and leg peripheral vascular resistance in patients with hypotension which might reflect a baroreceptor mediated compensatory increase in vasoconstrictor tone of muscle vessels not matched in other vascular territories.

Aged↗
PubMed1996

The venous wall and valvular function in chronic venous insufficiency.

The present paper is an overview taking into account the four most important etiological factors which can be involved in the development of chronic venous insufficiency (CVI): (1) weakness of the vascular wall including connective tissue and smooth muscle, (2) dysfunction and damage of the venous endothelium, (3) damage of the venous valves and (4) disturbancies of the microcirculation. The first three can be implicated in the development of reflux and venous hypertension and it is difficult to pin-point one single factor as being the most important. Disturbancies of the microcirculation eventually lead to the typical complications of CVI. With better understanding of the disease process it is possible to attack the causative factors leading to CVI and prevent and heal complications.

Capillary Permeability↗
PubMed1995

Cardiovascular effects of dobutamine stress testing in healthy women.

Dobutamine echocardiography is frequently used for detection of coronary artery disease. The circulatory response in patients is known to some extent, but studies in normals are lacking. Hypotensive response during the test is a common side effect, the cause of which is unclear. The aim of this study was, therefore, to investigate the hemodynamic response to dobutamine in women without cardiovascular disease and interfering medications. Eleven healthy women, age 53-71 years, were investigated with Doppler echocardiography and venous occlusion plethysmography during intravenous infusion of increasing doses of dobutamine according to a standardized protocol. An average peak dose of 22 +/- 7.5 micrograms kg-1 min-1 was administered. Cardiac output increased by 93%, heart rate by 68%, and stroke volume by 15%, while peripheral vascular resistance decreased by approximately 50%. Systolic blood pressure remained unchanged and diastolic blood pressure decreased by 21%. One subject demonstrated a decreased systolic blood pressure exceeding 10 mmHg. Outflow obstruction from the left ventricle was seen in two subjects, one of whom had a slight decrease of 10 mmHg in systolic blood pressure. Subjects > 65 years demonstrated a less pronounced increase in heart rate, cardiac output, and decrease in peripheral vascular resistance compared with those < 65 years.

Adrenergic beta-Agonists↗
PubMed1995

The effect of forskolin on blood flow, platelet metabolism, aggregation and ATP release.

UNLABELLED: Forskolin, a diterpene obtained from coleus forskolii, is a potent cAMP stimulator. We have evaluated the effects of forskolin on blood flow, platelet aggregation and metabolism. It was found that forskolin has a dose dependent vaso-relaxing effect in an in vivo sheep model, when infused intra-arterially. Furthermore forskolin, in a dose-dependent fashion reduced whole blood platelet aggregation and ATP release. Pretreatment of PTFE grafts with Forskolin significantly reduced platelet consumption 3 hours postoperatively and on the first postoperative day. The overall platelet metabolism, measured by a microcalorimetric technique after treatment with forskolin in vitro and ex-vivo postoperatively was significantly increased. IN CONCLUSION: Forskolin affects blood flow and platelet parameters favourably in the setting of occlusive arterial disease and reconstructive arterial surgery.

Adenosine Triphosphate↗
PubMed1995

Tilting enhances visualization of lower extremity veins with duplex colour flow imaging.

The present paper presents the results of a comparative analysis of the number veins and of the ease of visualisation of below the knee as displayed by colour Duplex scanning in both legs of 10 normal individuals in the horizontal and 40 degrees foot down tilted position. Foot-down tilting improves the ease of visualisation of lower leg veins by 38% and the number of visible branches by 28%. Therefore, this technique should preferably be employed in the diagnosis of deep vein thrombosis in order to improve diagnostic accuracy.

Adolescent↗
PubMed1994

Blood pressure responses in Japanese and Swedish children in the supine and standing position.

We investigated the cardiovascular responses to active standing in Swedish and Japanese pre-pubertal children using non-invasive continuous beat-to-beat finger blood pressure (BP) monitoring. Seventy-eight Swedish (7-12 years) and 53 Japanese children (6-12 years) were examined. There were no significant differences in body weight or height between the two groups (total group). Finger blood pressure and heart rate were continuously recorded in the supine position and during standing. Supine BP was significantly higher in Swedish compared to Japanese children (115/65 vs 98/50 mmHg, P < 0.001), and Swedish children showed a significantly larger initial BP drop upon rising (-28/15 vs - 14/ -10 mmHg, P < 0.05) and a larger increment of heart rate (39 +/- 10 vs 29 +/- 8 beats. min-1, P < 0.05). There were, however, no differences in the blood pressure and heart rate changes in the following steady state period (2-3 min) between the two groups. These results suggest that Swedish pre-pubertal children have a higher basal blood pressure and enhanced cardiovascular autonomic responses, such as pronounced baroreflex receptor sensitivity and vasoconstrictor mechanisms. These differences in the two cohorts were not related to body dimensions or degree of maturation, indicating that autonomic functions in the cardiovascular system largely depend on genetic factors and environmental variables.

Anthropometry↗
PubMed1994

The contractile response of thiopental in large and small ovine airways.

The present study addresses the question of bronchial reactivity towards thiopental using pharmacological assay and ultrastructural analysis with transmission electron-microscopy in sheep airways. Smooth muscle strips of the upper, middle and lower trachea and small size bronchial rings of sheep were investigated using organ bath technique with monitoring of isometric tension in response to thiopental (10(-7)-10(-4)M), histamine (10(-4)M) and carbachol (10(-8)M). Thiopental elicited contractile responses in the large airways, with most marked contractions in the upper trachea. In the small lobar bronchi thiopental caused a biphasic response with predominant relaxation. Similar reactions could be elicited by histamine. Ultrastructural studies showed a large number of mast cells with equal distribution throughout the bronchial tree. Histamine release from bronchial tissue was detected by bioassay after thiopental challenge. It can be concluded that thiopental at a concentration of 10(-4)M releases histamine from mast cells within the airways with consequent constriction in the trachea and mainly dilatation in the smaller intralobular airways. Under these conditions therefore, one does not necessarily expect a net change of airflow resistance with thiopental anaesthesia.

Animals↗
PubMed1994

Stretch-induced myogenic responses of airways after histamine and carbachol.

The purpose of the study described here was to determine the possible role of a myogenic response of bronchial smooth muscle in deep inspiration (DI)-induced bronchoconstriction. Model experiments were performed on sheep tracheal strips. The effect of sudden stepwise elongation on isometric tension of tracheal muscle was studied in the absence and presence of the bronchoconstrictors carbachol (10(-8) M) and histamine (10(-4) M). In control strips tension increased rapidly with stretch and was followed by stress relaxation which corresponds to creep or bronchial dilatation. In histamine- and carbachol-treated strips a reactive contraction with a rhythmic pattern interrupted the process of stress relaxation. These responses appeared after only 20% elongation and were characteristic of a myogenic contraction which in the in vivo situation would correspond to a bronchoconstriction. These findings are interpreted as a functional transformation of multiple- to single-unit smooth muscle due to the influence of carbachol and histamine. This suggests that stretching (DI) of bronchial smooth muscle in the presence of carbachol and histamine induces a protracted myogenic contraction, which may explain bronchoconstriction after DI in severe asthma.

Animals↗
PubMed1994

Continuous non-invasive finger blood pressure monitoring in children.

We evaluated the performance of continuous non-invasive finger arterial pressure measurement using the volume-clamp technique (Finapres). This study was designed to compare finger arterial pressure with brachial blood pressure estimated by the auscultatory method in 217 children (90 boys and 127 girls) aged 4-16 years and in 38 adults (aged 18-45 years). Finger and brachial artery pressure readings were obtained consecutively from the ipsilateral side in the supine position. Finger arterial pressure waveforms were recorded in all children except 4 with small and thin fingers. There was good agreement for systolic pressure with only a slight underestimation of 1.9 mmHg and 5.1 mmHg lower for diastolic pressure. This difference most probably reflects inaccuracy of the auscultatory cuff method rather than an error in the Finapres. There was large inter-individual variability in Finapres recordings which might be due to differences in vasomotor tone, as demonstrated by systolic amplification in 5 patients with anorexia. However, Finapres showed a small within-subject variability (3.8 mmHg for systolic and 4.1 mmHg for diastolic pressure) determined in 5 patients during phenylephrine infusion, and as good reproducibility as the auscultatory method. These results suggest that finger arterial pressure measurement in children older than 6 years of age has similar accuracy as that in adults, and that this method is useful for clinical applications in children, especially for the non-invasive evaluation of autonomic control and cardiovascular reflexes involving transient and rapid blood pressure changes.

Adolescent↗
PubMed1994

Circulatory responses in children with unexplained syncope evaluated by continuous non-invasive finger blood pressure monitoring.

Cardiovascular responses on active standing in children with unexplained syncope were investigated with continuous non-invasive finger artery pressure monitoring (Finapres). We examined 34 symptomatic patients (13 boys and 21 girls), aged 8-16 years, and 24 age-matched controls. Finger blood pressure and heart rate were monitored continuously for 5 min in the supine position and for 10 min while standing. Ten of 34 patients developed fainting symptoms with hypotension during upright posture (fainters). In the initial standing phase (0-30 s), two prominent abnormal blood pressure responses were found in patients: a marked decrease 45 +/- 18/23 +/- 8 mmHg and a prolonged recovery time (16.5 +/- 2.9 versus 27.7 +/- 13.6 s), which appeared to be based on impaired vasoconstriction. Either or both abnormalities were observed in 21 (62%) of the 34 patients and in 2 (8%) of the controls. In addition, fainters also had a more marked increase in heart rate during standing compared with non-fainters. Our findings suggested that more than half of children with syncope had abnormal cardiovascular reflexes in the initial phase which appeared to be associated with vasodepressor syncope. The active standing test with a continuous beat-to-beat blood pressure recording has a high sensitivity in detecting abnormalities of autonomic function in patients with unexplained syncope.

Adolescent↗
PubMed1994

[The pathophysiology of post-thrombotic syndrome].

The acute stage of venous thrombosis is characterized by an inflammatory process, therefore the term phlebitis is often erroneously equated with venous thrombosis. In most cases, however, the inflammatory reaction or phlebitis is a secondary phenomenon, associated with the process of fibrinolysis and phlebitis as a primary cause is rare. Postthrombotic sequelae such as edema, varicose veins and ulcers usually are late complications and can take a long time to develop. The primary cause of the postthrombotic syndrome is related to an injured venous wall, including damaged valves or stenosis due to incomplete recanalisation. The amount of damage is dependent on the extent of the primary thrombosis and the degree and rapidity of thrombolysis. When postthrombotic changes are suspected, functional evaluation can be performed with ambulatory venous pressure measurement in a foot vein or with the aid of non-invasive methods such as volumetry.

Humans↗