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Biomedical subjects

M Midttun

Publications and source records attributed to M Midttun.

15 recordsLinked to original sources
PubMed2006

Smokers have severely disturbed peripheral micro-circulation.

AIM: The aim of this study was to determine the effect of smoking a single cigarette on the blood flow rates in capillaries and arteriovenous anastomoses (AVAs) in light and heavy smokers in: a) the skin fold between the first and second fingers, and b) the pulp of the thumb. METHODS: Five light (10-12 cigarettes/day) and 5 heavy (>20 cigarettes/day) chronic smokers participated (4 men and 6 women, median age 40.5 years). The blood flow rates were measured by the (133)Xenon local washout method (capillaries, skin fold) and the heat washout method (AVAs, thumb pulp), respectively, before, during, and after smoking of a single Prince cigarette (0.9 mg nicotine). RESULTS: The blood flow rate (f) in mL(100 g(min)(-1) [standard error, SE] in skin capillaries of light smokers was 24.4 [9], 8.9 [1.8], and 10.4 [3.3] before, during, and after smoking of one cigarette; in heavy smokers, f was 23.6 [10.9], 16.1 [5.3], and 7.1 [2.9]; f in pulp AVAs of light smokers was 130.6 [14.9], 49.2 [24.8], and 119.7 [20.9] before, during, and after smoking; in heavy smokers, the corresponding results were 134.4 [19.1], 136.2 [13.5], and 143 [15.3]. Thus, the blood flow rate in capillaries of both light and heavy smokers was higher before smoking the test cigarette than previously observed in non-smokers. In light smokers blood flow rate in AVAs decreased during smoking with a factor of 2.6, and it returned to the pre-smoking level immediately after the end of smoking the cigarette. In heavy smokers, f remained unchanged before, during, and after smoking. CONCLUSIONS: Smokers have severely disturbed peripheral microcirculation.

Adult↗
PubMed2000

Blood flow rate in arteriovenous anastomoses: from the cradle to the grave.

Blood flow rate was measured in the arteriovenous anastomoses (AVAs) in the cutaneous tissue of the pulp of the first toe in 15 children between 3 and 15 years old, and in the pulp of the thumb and the first toe in 16 adults between 27 and 93 years old (two subjects from each decade) by the heat-washout method. The examinations showed that AVA-blood flow rate decreased with increasing age, and the difference between children and adults was highly significant (P=0.001). Blood flow rate in the finger pulp was higher than in the toe pulp (P=0.025). No significant difference in blood flow rate was found in either thumb pulp or toe pulp between men and women.

Adolescent↗
PubMed2000

Is non-specific aneurysmal disease of the infrarenal aorta also a peripheral microvascular disease?

OBJECTIVES: to examine whether aneurysmal disease of the aorta has a functional component in the peripheral microIvasculature. MATERIALS: ten normal persons; and 15 patients who had been operated on for ruptured non-specific infrarenal aortic aneurysm months to years previously were studied. METHODS: blood flow rates were measured: (a) in the subcutaneous adipose tissue of the forefoot by the(133)xenon local washout method (perfusion through nutritive capillaries supplied by arterioles with elastin in the tunica media); and (b) in the arteriovenous anastomoses of the pulp of the first toe as measured by the heat washout method (perfusion predominantly through thick-walled tubes without elastin). Perfusion rates were measured in supine subjects at heart level, at 30 cm above and at 30 cm below heart level. RESULTS: in subcutaneous adipose tissue, the capillary blood flow rate was four times higher in patients with aneurysmal disease than in normal subjects. Both groups exhibited autoregulation of blood flow and a normal veno-arteriolar sympathetic axon reflex. Blood flow rates in the arteriovenous anastomoses of the pulp did not differ between aneurysm patients and normal subjects. Autoregulation and the axon reflex were absent in the arteriovenous anastomoses of normal subjects as well as in aneurysm patients. CONCLUSIONS: non-specific aneurysmal disease of the infrarenal aorta has a peripheral functional component affecting arterioles but not arteriovenous anastomoses.

Adipose Tissue↗
PubMed1999

Peripheral blood flow rates and microvascular responses to orthostatic pressure changes in claudicants before and after revascularisation.

OBJECTIVES: To study the effect of arterial reconstruction for occlusive atherosclerotic disease with intermittent claudication on blood flow rate during rest and on microvascular responses to orthostatic pressure changes in the pulp skin of the first toe where arteriovenous anastomoses are numerous. MATERIAL: Eleven patients with Fontaine IIa claudication (ankle blood pressure index > 0.30) before and 7 (range: 2-11) months after intervention. METHODS: Blood flow rate was measured by the heat washout method with the toe at heart level and after passive lowering to 50 cm below this level using a Clark type electrode with thermostatically controlled cap that was fixed to the pulp of the first toe by adhesive tape. RESULTS: At heart level, blood flow rate was lower in claudicants before reconstruction as compared to a group of previously published control subjects (p = 0.0076, Wilcoxon), blood flow rate increased in claudicants from before to after intervention (p = 0.0128), and postoperative blood flow rate was like that of normals (N.S.). Before surgery, blood flow rate in claudicants increased in median with a factor of 1.79 during lowering (p < 0.0051). CONCLUSIONS: The disturbance of the microcirculatory responses to orthostatically induced pressure changes in claudicants reverted towards normal after arterial reconstruction.

Aged↗
PubMed1998

Cutaneous blood flow rate in areas with and without arteriovenous anastomoses during exercise.

In 10 healthy subjects, skin blood flow rate was measured in the thumb pulp by the heat-washout method, and in the skin fold between the thumb and the forefinger by the 133Xe-washout method. The former but not the latter skin area contains arteriovenous anastomoses (AVAs). In response to 10 min moderate bicycle exercise, an instantaneous decrease in flow was seen in the thumb pulp followed after about 4.6 min by an increase to resting levels. Blood flow in the skin fold remained constant. The results indicate that the initial reduction in blood flow rate and later increase observed in the finger at the onset of moderate exercise take place in the AVAs and not in the capillaries.

Adult↗
PubMed1997

Blood flow rate during orthostatic pressure changes in the pulp skin of the first toe.

OBJECTIVES: Determination of the local regulation of cutaneous blood flow through nutritive capillaries and through arteriovenous anastomoses of the pulp of the first toe in response to passively induced orthostatic blood pressure changes in normal subjects and in patients with occlusive atherosclerotic disease. MATERIAL: Six normal subjects, seven patients with unilateral, crural intermittent claudication and six patients with unilateral, chronic critical ischaemia. METHODS: Blood flow rates were measured in supine subjects by the heat washout method (the sum of blood flow rate in arteriovenous anastomoses and blood flow rate in nutritive capillaries) and by the 133Xenon washout method (blood flow rate in nutritive capillaries) after local, atraumatic labelling. Measurements were made with (a) the toe passively elevated to 50 cm above heart level, (b) at heart level and (c) passively lowered to 50 cm below heart level. RESULTS: Autoregulation of nutritive blood flow was present in normal subjects and in claudicants, but the local sympathetic veno-arteriolar axon reflex was absent in both groups. In patients with critical ischaemia blood flow rate was the same in the supine position and during lowering in arteriovenous anastomoses and in nutritive capillaries. The arteriovenous anastomoses had distinct and characteristic reaction patterns in response to lowering in each of the three examined groups and to elevation in normal subjects and in patients with intermittent claudication (not measured in patients with critical ischaemia). CONCLUSIONS: The microvascular responses to changes of orthostatic blood pressure differed among the three groups (normal subjects, patients with intermittent claudication, patients with critical chronic leg ischaemia). The heat washout method may be used to detect the functional significance of occlusive atherosclerotic disease.

Adult↗
PubMed1997

Lyme carditis: a clinical presentation and long time follow-up.

The acute disease and a follow-up carried out up to 7 years after definite Lyme carditis in 6 patients is described. At the time of diagnosis all 6 patients had 2-3 degrees AV block, 4 patients presented with syncopes, and 1 revealed episodes of non-sustained ventricular tachycardia. The diagnosis of Lyme carditis was confirmed by Borrelia burgdorferi-specific IgM and IgG antibody determinations in consecutive serum samples. All patients were treated with antibiotics. At follow-up, a clinical examination, a 2D and M-mode echocardiogram, and an exercise test did not reveal sequelae to Lyme carditis.

Adult↗
PubMed1996

Heat-washout: a new method for measuring cutaneous blood flow rate in areas with and without arteriovenous anastomoses.

A new method, the heat-washout method, for measuring total cutaneous blood flow rate is introduced. The measurements were performed with a transcutaneous (tc) PO2-electrode that is capable of heating and measuring local temperature, and it is constructed with a thermostatically controlled cap. The probe was heated electrically to a selected temperature 2-10 degrees above normal skin temperature. When the temperature was stable, the heating element was turned off, and the temperature was registered every 10 s until a stable baseline temperature, Tb, was obtained. Tb was subtracted from the registered temperatures giving deltaTs that were plotted in a semilogarithmic diagram. The heat-washout was monoexponential, and the slope was used for calculating blood flow rate in accordance with the principle of Kety, using a known partition coefficient. The method was applied to the forearm in two subjects, and the results were compared to blood flow rates obtained simultaneously by the 133Xe-washout method in the same area. The equation of the regression line was y = 2.5 + 0 x 968X and the correlation coefficient was 0 x 986 at temperature levels of 37-45 degrees C. In the pulp of the thumb, blood flow rates, in arteriovenous anastomoses, were estimated in two subjects by subtracting the capillary blood flow rate, measured by 133Xe-washout, from the total cutaneous blood flow rate, measured by heat-washout. Due to a relatively low diffusions coefficient for 133Xe compared to heat, 133Xe cannot be used for measurement of blood flow rate in arteriovenous anastomoses.

Adult↗
PubMed1996

Blood flow rate in arteriovenous anastomoses and capillaries in thumb, first toe, ear lobe, and nose.

Measurements of blood flow rate in the pulp of the thumb, the first toe, the ear lobe, and the nose were performed using the heat-washout method, and the 133Xe-washout method under orthostatic changes in humans. Blood flow rate measured by the heat-washout method in the thumb was about 127.5 ml (100 g x min)-1 at heart level in two subjects, (n=10), and in the pulp of the first toe in 6 subjects (n=12) 49.3 ml (100 g x min)-1 at heart level. Above heart level blood flow rate decreased with the falling pressure head, and 50 cm below heart level blood flow remained unchanged compared to heart level. The arterioles supplying the capillaries in this region showed autoregulation of blood flow to 50 cm above heart level, but a veno-arteriolar reflex was not present. Blood flow rate in the ear lobe and on the side of the nose showed a similar pattern of reaction, with a blood flow rate in the arteriovenous anastomoses of about 100 ml (100 g x min)-1 in sitting position.

Adult↗
PubMed1994

The Bullard laryngoscope. Reports of two cases of difficult intubation.

The Bullard laryngoscope is a new combination of a fibreoptic light source and an anatomically shaped rigid blade, to aid visualization of the larynx. We present two patients with expected severe difficult endotracheal intubation and describe their anaesthetic management. Our experience confirms previous observations which showed that the Bullard laryngoscope provides an excellent view of the vocal cords in patients with severe difficult airways.

Epiglottis↗
PubMed1993

[Serious arrhythmias in Borrelia infections].

Carditis is seen in about 4-10% of cases of Lyme's disease. It is usually dominated by varying degrees of atrioventricular block, and implantation of a temporary pacemaker may be necessary. Ventricular and supraventricular tachycardias seem to be less frequent than block, and as far as we know ventricular tachycardia provoked by bradycardia has not been reported previously. Third degree AV-block after oral penicillin treatment of erythema migrans is unusual in Europe. When an atrioventricular block of unknown origin is diagnosed, Lyme carditis must be considered, especially among young patients.

Adult↗
PubMed1993

[Noisy pneumothorax. Clicking pneumothorax mimicking pericarditis].

A clicking, crackling, or crunching sound over the cardiac apex, sometimes followed or accompanied by left-sided chest pain, is usually thought to be caused by pericarditis. It is frequently ignored that these symptoms can be due to a small left-sided pneumothorax, called noisy pneumothorax. The pneumothorax can be visualized on X-ray taken in full expiration. Noisy pneumothorax can be followed by various electrocardiographic changes, thus simulating myocardial infarction and other serious heart diseases. Therefore, it is important to have this differential diagnosis in mind as a possibility when healthy, young people are admitted to the hospital with heart symptoms. Two cases of noisy pneumothorax simulating pericarditis are described.

Adult↗
PubMed1990

[Thrombocyte aggregation and serum thromboxane in patients with acute myocardial infarction].

Treatment with acetylsalicylic acid reduces the mortality following acute myocardial infarction (AMI). The mode of action is unknown but studies of patients with unstable angina pectoris have revealed that acetylsalicylic acid inhibits the platelet aggregating and vessel-constricting metabolite thromboxane B2. In the present investigation, we have examined ten patients with AMI. Platelet aggregation induced by arachidonic acid and serum thromboxane B2 were compared with findings in patients with unstable angina pectoris and healthy control persons. The investigation reveals that the platelet aggregateability is increased significantly already on the first day after AMI and increases in all cases for 14 days (p less than 0.001). Serum thromboxane B2 concentration is normal on the first day and increases gradually in the course of 14 days (p less than 0.05) to values which are not significantly different from those observed in patients with unstable angina pectoris. Patients with AMI have significantly increased platelet aggregation and increasing concentrations in the blood of thromboxane B2. Acetylsalicylic acid inhibits platelet aggregation and lowers thromboxane B2 concentration in the blood which may explain the effect of this preparation in reducing the mortality after AMI.

Aged↗