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Biomedical subjects

R Cronestrand

Publications and source records attributed to R Cronestrand.

13 recordsLinked to original sources
PubMed1979

Conversion of arachidonic acid to prostaglandins in homogenates of human skeletal muscle and kidney.

The capacity of human skeletal muscle and kidney homogenates to synthetize prostaglandins (PGs) from exogenous precursor was investigated. Low-speed supernatants of muscle as well as renal medullary and cortical homogenates were incubated with 14C-labelled arachidonic acid (14C-AA) prepared as a sodium salt. 14C-PGs in the incubates were extracted, separated with thin-layer chromatography (TLC) and quantified by radioscanning. In the skeletal muscle incubates 14C-AA was converted into 14C-PGs with a time-dependent yield, most effectively after 10--15 min incubation. Well-defined radiopeaks parallel to unlabelled standards of PGD2, PGE2, PGF2 alpha and 6-keto-PGF1 alpha were obtained in the chromatograms. PGE2 was the main PG formed, constituting over 50% of 14C-activity, whereas 6-keto-PGF1 alpha, PGD2 and PGF2 alpha were found in considerably lower proportions. In the renal medullary incubates, PGE2 likewise accounted for the largest part of 14C-PGs formed, but significant relative amounts of PGF2 alpha and PGD2 were also found. A minor peak, corresponding to 6-keto-PGF1 alpha and thus indicating formation of PGI2, was also obtained. In contrast to the medulla, no 14C-PGs could be found in the renal cortical incubates. The results demonstrate the existence of a considerable tissue specificity in the quantitative and qualitative expression of PG biosynthesis in man.

Adult↗
PubMed1979

LEg venous oxygen saturation in the evaluation of intra-operative blood flow during arterial reconstructive surgery.

In twenty-four patients, undergoing a femoro-popliteal saphenous vein bypass graft for symptomatic atherosclerotic occlusion of the superficial femoral artery, oxygen saturation values for the femoral and popliteal veins were compared to the directly measured blood flows in the common femoral artery and in the bypass graft, respectively. Blood flow and venous oxygen saturation increased significantly after transfusion of 900 ml of blood. Pharmacological vasodilation caused a significant increase in blood flow both before and after transfusion, whereas the changes in venous oxygen saturation were significant only before blood transfusion. A close statistical relationship was found between initial femoral venous oxygen saturation and initial blood flow in the common femoral artery as well as between initial popliteal venous oxygen saturation and initial byapss blood flow. However, especially at low saturation values, the evaluation of blood flow was very uncertain. Whole leg and lower leg oxygen uptakes were not altered by intraoperative changes in blood volume. It is concluded that blood flow in the common femoral artery and the bypass graft can be roughly estimated from analysis of oxygen saturation in the femoral and popliteal veins, respectively. Furthermore, by determining leg venous oxygen saturation both before and after flow augmentation, induced by pharmacological vasodilation, a conception of the load on the vascular system may be obtained.

Aged↗
PubMed1979

Prognostic significance of intra-operative blood transfusions and flow measurements in reconstructive vascular surgery.

Intra-operative measurement of leg blood flow is useful not only for the detection of a technical fault. It has also proved to be a sensitive method to disclose hypovolaemia. Thus, if the blood volume is not restored, the peripheral vasoconstrictor tone remains elevated. In such a state, the basal leg blood flow is low, but increases markedly on pharmacological vasodilation. In a normovolaemic situation, however, the basal blood flow is higher with a less pronounced increase following vasodilation. In the present study, intra-operative measurements of graft blood flow using an electromagnetic flowmeter have been employed to evaluate the blood substitution needed during 114 consecutive reconstructions with femoro-popliteal reversed saphenous vein bypass grafts. The measurements resulted in a blood transfusion therapy that was, on an average, 38% higher that it would have been, if substitution had been based simply on a calculation of blood losses from volume measurements in the suction apparatus and from the drapes and swabs. Only three graft thromboses developed within the first month. The flow rate of these grafts was much lower than the grafts remaining open. The low early thrombosis frequency (2.8%) compares favourably with previous reports, which might partly be explained by generous intra-operative blood transfusion.

Adult↗
PubMed1978

Leg blood flow and central circulation at varying blood volumes. An intra-operative study of nine patients undergoing a femoro-popliteal vein bypass graft.

Common femoral arterial and bypass blood flows, cardiac output, brachial arterial and central pressures were measured in nine patients undergoing a femoro-popliteal vein bypass graft for intermittent claudication. The measurements were performed during neuroleptanesthesia before the operation, after the operation before blood substitution and then after transfusions of 450,900 and 1350 ml of blood. The leg blood flows were measured before and during local vasodilatation induced by intra-arterial injection of bamethane (Vasculat). The bypass flow was only 55 ml/min before blood substitution but was increased to 215 ml/min after the blood transfusions. The corresponding values for the common femoral artery were 100 ml/min and 430 ml/min, respectively. The maximal flow in the bypass vein during vasodilatation with bamethane (Vasculat) was 145 ml/min before blood substitution and 270 ml/min after the transfusions. This implies that the flow response to vasodilatation was more pronounced before than after blood substitution. The leg blood flow increased proportionally more than cardiac output on blood substitution. It is concluded that leg blood flow is very sensitive to hypovolemia and can be increased considerably by adequate blood substitution. The flow response to local vasodilatation is proportionally higher during hypovolemia.

Adult↗
PubMed1978

Estimation of femoral arterial blood flow from femoral venous oxygen saturation.

In six patients in whom a femoro-popliteal vein bypass graft was performed for intermittent claudication, the relationship between the haemodynamic state of the leg and the femoral venous oxygen saturation before and after local vasodilatation was investigated. The study was undertaken with special reference to the known influence of hypovolaemia on the leg blood flow. It is concluded that a femoral venous oxygen saturation below 70%indicates that the leg blood flow is less than 200 ml/min and that the bypass flow is less than 100 ml/min and thus within a range in which the incidence of early thrombosis is high. Furthermore, an increase in femoral venous oxygen saturation of 10% or more on local vasodilatation indicates a state of hypovolaemia, necessitating further blood substitution.

Arteriosclerosis Obliterans↗
PubMed1977

Leg blood flow and central circulation at various blood volumes: a peroperative study of nine patients with varicose veins.

1. In a group of nine middle-aged patients undergoing varicose vein surgery, cardiac output, right atrial, pulmonary arterial and capillary pressures, and leg blood flow were measured after induction of general anaesthesia but before operation, and also during operation before and after blood substitution. 2. Under anaesthesia, the mean pre-operative blood flows in the superficial and common femoral arteries were 160 ml/min and 280 ml/min respectively. These flows are comparable with those obtained in other studies under similar conditions but lower than values obtained in conscious subjects. During the operation the leg blood flow decreased by 24%. As cardiac output remained unchanged, the fractional leg blood flow fell. After transfusion of 900 ml of blood the leg blood flow doubled. 3. It is concluded that anaesthesia, surgical trauma and variations in blood volume greatly influence the leg blood flow and that an adequate substitution of operative blood loss is of utmost importance to achieve an optimum peripheral circulation.

Adult↗
PubMed1977

The cardiovascular effects of neuroleptanaesthesia.

Oxygen uptake, cardiac output, stroke volume and arterial and central blood pressures were measured before and after induction of neuroleptanaesthesia in 27 subjects. Nine were elderly patients operated on for obliterative arteriosclerotic disease, and the other 18--nine elderly and nine younger patients--underwent operation for varicose veins. Cardiac output, stroke volume and systolic arterial blood pressure decreased significantly with a corresponding decrease in oxygen uptake. The changes were most pronounced in the patients with arteriosclerotic disease. The arterio-venous oxygen difference was unchanged in the arteriosclerotics and decreased in the other two groups. The central pressures remained unchanged in all groups. It is concluded that the cardiovascular changes induced by neuroleptanaesthesia are due to a decrease in oxygen uptake and not to myocardial depression.

Adult↗
PubMed1977

Leg blood and central circulation at varying blood volumes. A peroperative study of nine young patients with varicose veins.

Cardiac output, central pressures and leg blood flow wre studied in a group of nine young individuals undergoing surgery for varicose veins. These subjects did not differ from older ones in an earlier, corresponding study in respect of central or femoral blood flow. The haemodynamic affects of peroperative variations of the blood volume were also the same. Thus, the common femoral arterial blood flow decreased by 40% from a mean of 450 to 260 ml/min during the operation. After transfusion of 900 ml of blood the flow increased to 575 ml/min. As a low blood predisposes to thrombosis, it is concluded that, irrespective of age, adequate peroperative volume substitution is of great importance in counteracting such a risk.

Adult↗
PubMed1975

Leg blood flow and muscle metabolism in occlusive arterial disease of the leg before and after reconstructive surgery.

1. Leg blood flow, uptake of oxygen and glucose and release of lactate by the leg and changes in intramuscular concentrations of metabolites were studied at rest and during exercise of increasing work loads in thirteen patients with occlusive disease of the iliac or superficial femoral arteries. 2. Leg blood flow (dye-dilution technique) and oxygen uptake during exercise were low and levelled with increasing work load. Considerable increases were noted in muscle lactate concentration and in the net release of lactate from the exercising leg. Muscle content (needle-biopsy technique) of ATP and creatine phosphate decreased during exercise, with an almost complete depletion of creatine phosphate in three patients. The decrease in muscle glycogen during work did not differ significantly from that of control subjects. 3. Repeated exercise after reconstructive surgery showed a considerable improvement in physical working capacity. Leg blood flow and oxygen uptake during exercise were significantly higher than before surgery and increased linearly in relation to work intensity. The decrease in creatine phosphate and lactate concentration of the thigh muscle during exercise was less pronounced and the release of lactate was lower than before vascular reconstruction. 4. It is suggested that the onset of the severe muscle symptoms during exercise in patients with occlusive arterial disease of the leg may be related to a low concentration of ATP and creatine phosphate in the affected muscles.

Adenosine Triphosphate↗