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Biomedical subjects

B Fagrell

Publications and source records attributed to B Fagrell.

At least 73 records · Page 4Linked to original sources
PubMed1987

Skin microvascular blood flow control in long duration diabetics with and without complications.

The integrity of the regulation of skin microvascular blood flow has been studied in Type 1 diabetic patients with and without clinical evidence of microvascular complications after a long duration of diabetes. 13 uncomplicated patients with a mean duration of diabetes of 38 +/- 6 (SD) yr were compared with 10 patients with proliferative retinopathy and a group of healthy control subjects. Using laser Doppler flowmetry 2 distinct microvascular responses were examined in the skin of the finger: (a) reactive hyperaemia following the release of one minute's digital arterial occlusion, a response that is independent of neural mechanisms, and (b) the fall in skin blood flow on venous occlusion that occurs due to the veno-arteriolar reflex, a response that depends upon intact local sympathetic nervous function. The duration of reactive hyperaemia was longer in the complicated patients than either the group without complications (69 +/- 38: 23 +/- 17 s, p less than 0.01) or the healthy controls (27 +/- 20 s, p less than 0.05). In contrast the percentage fall in laser Doppler blood flow on venous occlusion was significantly less (p less than 0.01) in both diabetic groups than that achieved in healthy controls, (50 +/- 14% controls; 26 +/- 12% uncomplicated group; 28 +/- 12% patients with retinopathy). There was no difference in current or recent diabetic control in the 2 diabetic groups. These results suggest that some degree of sympathetic neuropathy is almost inevitable after a long duration of Type 1 diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1986

Clinical studies of skin microcirculation.

In this survey several methods for studying skin microcirculation are presented. The technical characteristics and the clinical applicability of vital capillary microscopy, laser doppler flowmetry, skin fluorescein angiography and transcutaneous pO2 measurement are described.

Capillaries↗
PubMed1986

Microcirculatory methods for the clinical assessment of hypertension, hypotension, and ischemia.

New techniques are now available for studying skin microcirculation non-invasively in humans. The clinically most useful ones are laser Doppler flowmetry, vital capillaroscopy, dynamic capillaroscopy and fluorescence microscopy. Some of these techniques have now been used in clinical practise for studying the reactivity of the skin microcirculation in patients with hypertension, hypotension and ischemia. It was found that the reactivity to stress in patients with hypertension can be quite different in the skin microvascular bed as compared to the total circulation of the region. In patients with local hypotension due to an arterial obstruction the postocclusive reactive hyperemia response is significantly changed compared to normals. The vasomotion activity is also decreased in the low pressure area. A marked decrease in the local blood pressure may lead to tissue ischemia. In these patients the risk of skin necrosis can be evaluated by microscopic classification of the structural changes of the capillaries in the area of ischemia. When the skin capillaries are void of erythrocytes the risk of necrosis is imminent.

Biomedical Engineering↗
PubMed1986

Acrodermatitis chronica atrophicans Herxheimer can often mimic a peripheral vascular disorder.

During the past few years five patients have been referred to the angiology section at Danderyd Hospital under the diagnosis of chronic venous insufficiency but who were instead suffering from acrodermatitis chronica atrophicans (ACA). The typical case of ACA starts with a limited inflammatory lesion, which is gradually replaced by atrophy and the skin shows a bluish, red discoloration. Late changes may be subluxation of joints in hands or feet and periosteal thickening. Capillary microscopy often reveals a clear picture of atrophy and a prominent, dilated subpapillary venular plexus. If localized to the leg the blood flow of the foot and lower leg may be increased, skin temperature elevated and venous capacity and return augmented. All these variables can consequently mimic venous insufficiency of the leg. ACA is caused by a Borrelia infection and serological testing will always show a significantly elevated titer to Borrelia. The disease is most often easily cured by 2-3 g of penicillin daily for two to three weeks.

Acrodermatitis↗
PubMed1986

The relationship between macro- and microcirculation clinical aspects.

A large number of methods are today available for the clinical evaluation of the arterial blood supply to an extremity or part of an extremity. However, these methods are not sensitive enough for determining the nutritional status of a tissue in the extremity affected by vascular disorders. This is especially true for the skin where most of the blood is used for thermoregulation and only a small fraction goes through the nutritional capillaries. Blood may enter the subpapillary vascular network through AV-shunts and bypass the nutritional skin capillaries. Therefore microcirculatory methods has to be used in order to be able to evaluate the nutritional status of a certain skin area. One of the clinically most useful methods for this purpose is vital capillary microscopy. By classifying structural changes of the nutritional capillaries in an area susceptible to ischemia, the risk of necrosis can be evaluated. Marked discrepancies between the total circulation of the are and the nutritional status of the tissue can be seen especially in patients with peripheral vascular disorders and/or diabetes. The total circulation may be markedly reduced but necrosis does not occur until the nutritional circulation of the ischemic skin area is completely abolished for a certain period of time. On the other hand it is sometimes seen in clinical practise that ischemic skin necrosis may develop in a region with rather good macrocirculation. These findings are of utmost importance when the effect of a certain treatment should be evaluated. The effect has to be studied directly in the target organ, and that is the nutritional vascular bed of the ischemic area.

Arteriosclerosis↗
PubMed1986

Microcirculatory methods for evaluating the effect of vasoactive drugs in clinical practice.

Microcirculatory methods have to be used in order to be able to evaluate the effect of vasoactive drugs in ischemic skin areas. During the past two decades several new such techniques for studying the microcirculation in man have been developed. These techniques have shown to be of great value for evaluating drug effects in patients with disturbed peripheral circulation. One such method is the non-invasive Laser Doppler technique. It measures both the nutritional and the non-nutritional thermoregulatory vascular bed of the skin. The data achieved are only semiquantitative, but the method has been shown to be clinically very useful for studying the dynamics of total skin microcirculation in a specific area. In order to be able to study directly what happens in the nutritional capillaries microscopical methods have to be used. Two such techniques are available in clinical practice. By an ordinary light microscope the capillaries can be directly visualized. A specific classification system can be used to evaluate the degree of ischemic damage to an area. The effect of different kinds of therapeutic procedures for improving the microcirculation in an ischemic area can be easily evaluated. By the combination of a light microscope and a sensitive TV-camera the blood flow in single skin capillaries can be measured at a magnification of 250-1 000 times. This method is well suited for testing the immediate effects of vasoactive substances on the nutritional skin circulation both in healthy subjects and in patients with different kinds of cardiovascular diseases.

Capillaries↗
PubMed1986

Testicular microcirculation in the rat studied by videophotometric capillaroscopy, fluorescence microscopy and laser Doppler flowmetry.

Testicular capillary blood flow was studied in rats using laser Doppler flowmetry, in vivo fluorescence microscopy and videophotometric capillaroscopy. All the methods revealed rhythmical oscillations in testicular microcirculation with a periodicity of 4-10 c.p.m. In arterioles, capillaries and small post-capillary vessels, periods of continuous blood flow alternated with periods of no or very low flow. No visible leakage of dextran-150 was observed from the testicular blood vessels. Four, 8 and 16 h after an s.c. injection of 200 IU hCG the blood flow was continuous and there was leakage of dextran-150 from the microvessels to the interstitial tissue. Twenty-four and 32 h after hCG the blood flow pattern was again rhythmical, and at 32 h there was no leakage of dextran-150. This suggests that hCG induces changes in blood flow and transvascular fluid exchange in the testis, perhaps by altering smooth muscle activity at the arteriolar-level.

Animals↗
PubMed1986

Skin capillary blood cell velocity in man. Characteristics and reproducibility of the reactive hyperemia response.

Measurements of human skin capillary blood cell velocity (CBV) were performed by videophotometric capillaroscopy using a crosscorrelation technique. Mean resting (r) CBV in a group of 64 healthy subjects (age 20-82; 33 men) was 0.60 +/- 0.51 (SD) mm/s at a skin temperature of 30.9 +/- 3.2 degrees C. Skin temperature, but not rCBV, was significantly higher in the men. rCBV showed a weak positive correlation with skin temperature with a marked increase of high rCBV values when skin temperature was more than 31 degrees C. During the postocclusive reactive hyperemia (PRH) after a one-minute arterial occlusion, CBV reached a maximal velocity of 1.17 +/- 0.66 mm/s at 7.8 +/- 2.4 s after cuff release. This PRH response was reproducible with regard to peak velocity (pCBV) and the time to pCBV. The percentage increase of CBV during PRH was inversely correlated to skin temperature (r = -0.69). The results of the present study are proposed as a basis for further studies of human skin capillary circulation in health and disease.

Adult↗
PubMed1985

Dynamics of skin microcirculation in humans.

The human cutaneous microcirculation has so far been studied by rather crude methods, such as plethysmography and 133Xn clearance. New sophisticated and noninvasive techniques are now available, with which the microcirculation of the skin can be continuously studied and measured for hours. With two such methods, i.e., Laser-Doppler flowmetry and dynamic capillaroscopy, fast dynamic fluctuations of the microcirculation can be followed. Under resting conditions, the total skin flow of a small area (1-2 mm2) varies consistently with time. These variations are caused by the arterial pulse, but also by active vasomotion with a frequency of about 4-8 cycles/min. These fluctuations can also be seen in single skin capillaries, but with a somewhat faster frequency: 6-10 cycles/min. The reaction of the cutaneous microcirculation to provocation tests, such as postocclusive reactive hyperemia response and venous occlusion (50 mm Hg), can also be studied. The time to peak during postocclusive reactive hyperemia is very consistent. In response to venous congestion, capillary flow rate falls drastically, whereas Laser-Doppler flow is much less dramatically reduced. These discrepancies suggest that the Laser-Doppler flowmeter records blood flow in skin vessels in addition to the superficial, nutritional capillaries. The dynamic pattern of the skin microcirculation is altered in patients with hypertension, diabetes, and obstructive arterial disease.

Blood Flow Velocity↗
PubMed1985

One-month versus six-month therapy with oral anticoagulants after symptomatic deep vein thrombosis.

The length of time for which deep vein thrombosis (DVT) should be treated with oral anticoagulants (OA) is controversial. In this study, 135 patients with symptomatic first period DVT (83% with proximal DVT) were randomly allocated to OA for one or six months. The diagnosis of initial and recurrent DVT was confirmed by phlebography or plethysmography and thermography, or by a combination of all these methods. Pulmonary emboli were confirmed by lung scans or at autopsy. The patients were followed for at least one year. One patient had to discontinue OA prematurely because of haemorrhage. Seventeen patients left the project for other reasons, ten during and seven after therapy; in one of these DVT recurred. The recurrence rate during the first year was high (17% symptomatic recurrences) irrespective of whether OA had been given for one or six months.

Adult↗
PubMed1985

Skin capillary blood cell velocity in patients with arterial obliterative disease and polycythaemia: a disturbed reactive hyperaemia response.

Nailfold skin capillary blood cell velocity (CBV) was studied at rest and during post-occlusive reactive hyperaemia after a 1 min arterial occlusion (PRH1) in: (i) both hands of patients with arterial obliterative disease (AOD) of one arm, (ii) patients with polycythaemia, before and after a moderate haemodilution and (iii) healthy controls. CBV was analysed by videophotometric cross-correlation utilizing the different optical densities produced by the passage of erythrocytes, leucocytes and plasma gaps through the monitored capillary. Resting CBV in the patients with unilateral AOD was similar in equivalent fingers of both hands. However, the time to peak (p)CBV during PRH was significantly prolonged in the low-pressure arm as compared to the contralateral arm. pCBV was also delayed in the patients with polycythaemia as compared to the healthy controls. This delay was not affected by the replacement of 500-750 ml of blood with the same amount of a 6% Dextran 70 solution. The mean capillary blood cell velocity during rest (rCBV) did not differ between controls and patients before or after the haemodilution. The prolonged time to pCBV in the polycythaemic patients may be attributed to increased blood viscosity that is presumably not significantly influenced by a moderate haemodilution using Dextran 70. The marked delay to pCBV observed distal to the arterial obstruction in patients with AOD probably is an effect of the lower arterial pressure, presumably involving an alteration of vascular smooth muscle function.

Aged↗
PubMed1985

Skin microvascular autoregulatory responses in type I diabetes: the influence of duration and control.

We have studied skin microvascular autoregulatory responses in healthy control subjects (n = 11) and three subgroups of uncomplicated Type 1 diabetics. Group 1 (n = 10) had a duration of diabetes of less than one year. Group 2 (n = 10) had a mean duration of diabetes of 11 years. Group 3 (n = 9), of similar duration to group 2, were selected on the basis of having HbAl values persistently below 9%. To assess autoregulatory capacity we determined time to peak capillary flow velocity (CBV) in single nailfold capillaries following release of 60 s arterial occlusion by videophotometric capillaroscopy, and the percentage fall in finger skin rest flow measured by laser Doppler flowmetry when 50 mm Hg venous occlusion was applied. Time to peak CBV was prolonged in groups 1 and 2 compared to controls, (controls 7.7 +/- 1.4 s, mean +/- ISD, group 1 10.7 +/- 2.9 s, p less than 0.01; group 2 11.6 +/- 3.0 s, p less than 0.002) but not in group 3 (9.3 +/- 3.0 s, NS). The percentage fall in resting microcirculatory flow in response to venous occlusion was reduced in groups 1 and 2 compared to controls (controls 57 +/- 16%, group 1 40 +/- 19%, p less than 0.05; group 2 22 +/- 16%, p less than 0.002). In group 3 the response was significantly different from the control value (group 33.7 +/- 20%, controls 57 +/- 16%, p less than 0.05). Thus skin microvascular autoregulatory responses are disturbed within the first year of diabetic life and after 10 years disease duration the impairment is more marked.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

The effects of intravenous insulin infusion on skin microcirculatory flow in Type 1 diabetes.

The effects of insulin infusion (1.5 u/h and 15 u/h) on finger nailfold capillary diameter, microcirculatory resting flow and microvascular reactivity were studied in eleven Type 1 diabetics. Blood glucose was maintained at pre-infusion values by intravenous glucose infusion as necessary. Venous limb capillary diameter was significantly wider on 15 u/h compared with pre-infusion values (14.3 +/- 4.5 micron pre, 16.9 +/- 5.1 micron 15 u/h, p less than 0.01. Resting blood flow measured by laser doppler flowmetry increased on the low dose infusion compared with pre-infusion values (2.6 +/- 1.7 V pre, 3.3 +/- 1.9 V 1.5 mu/h, p less than 0.05) but fell on high dose infusion (2.5 +/- 1.9 V, p less than 0.02). Dynamic measurement of capillary blood flow velocity in single capillaries suggested that insulin infusion increased the circulatory debt repayment following 60 s arterial occlusion. The high dose infusion caused a significant impairment of the reflex rise in precapillary resistance that normally accompanies venous congestion. It is concluded that insulin has effects on skin microvascular haemodynamics that are independent of the hormone's hypoglycaemic action.

Adult↗