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Biomedical subjects

K Alexander

Publications and source records attributed to K Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1998

Sailing without radar: an excursion in resource allocation.

This paper deals with the knowledge base employed in resource allocation. It deliberately distinguishes between 'thick-textured' and 'thin-textured' knowledge. A thick-textured view of change in the health sector accounts for the history, civic goods and variety of human needs and passions which rationalist economics defines out as a thin-textured matter of individual choices in a free market. The narrative material begins with a discussion of health service policy-making in South Australia and elsewhere in the 1980s and 1990s, then proceeds to a discussion of priority-setting literature, which we regard as thin-textured. We offer two accounts of approaches to setting priorities in health care which we think have overcome some of the deficiencies of the thin-textured approach.

Community Participation↗
PubMed1998

Prostaglandin E1 in peripheral vascular disease: a PET study of muscular blood flow.

BACKGROUND: Increase of blood flow in the ischaemic leg is believed to represent the main action of prostaglandin E1 (PGE1) in the therapy of peripheral vascular disease (PVD). There is no reliable data in man concerning the amount of increase in muscular blood flow (MBF) of the calf, and the difference between intra-arterial and intravenous application. PATIENTS AND METHODS: We conducted a positron emission tomography (PET) study of MBF with 15O-water as flow tracer. Fifteen patients with PVD and three healthy volunteers were given 5 micrograms PGE1 intra-arterially over 50 min; PET scans were taken at 0, 25 and 50 min. Additionally, eight of the patients were investigated during an intravenous infusion of 40 micrograms PGE1 over 120 min; PET scans were taken at 0, 30, 60 and 120 min. RESULTS: Increase of muscular blood flow by intra-arterial PGE1 averaged 80%. A steal phenomenon was not observed. The amount of flow enhancement depended on whether or not the femoral artery was patent. During intravenous PGE1, muscular blood flow remained unchanged. CONCLUSIONS: In man, the pharmacodynamic profile of intra-arterial PGE1 differs clearly from intravenous PGE1. The flow-enhancing property is lost during metabolization in the lung. Since no difference exists between the therapeutic efficacy of intraarterial and intravenous PGE1, the impact on muscular blood flow is not as important as suggested previously.

Adult↗
PubMed1998

Aerobic exercise for a patient with chronic multisystem impairments.

Many patients with long-term disabilities have inactive lifestyles that put them at risk for chronic diseases and secondary disabilities. The purpose of this case report is to illustrate the process of aerobic exercise prescription for a patient with chronic multisystem impairments. The patient was a 43-year-old man who incurred a traumatic brain injury and multiple fractures in a motorcycle accident 15 years previously. He subsequently developed heterotopic ossification around the right hip. In addition, the patient had a history of smoking. We chose a "nontraditional" mode of exercise for the patient that we believed would be safe and effective and would accommodate his neurologic and orthopedic impairments. The mode of exercise used was an apparatus in which the upper and lower extremities alternately flexed and extended in a nonreciprocal fashion. The patient attended 12 exercise sessions over a 1-month period, during which he demonstrated acute and chronic physiological responses appropriate for the exercise stimulus.

Activities of Daily Living↗
PubMed1998

Intra-arterial and intravenous administration of prostaglandin E1 cause different changes to skin microcirculation in patients with peripheral arterial occlusive disease.

BACKGROUND: Disturbed skin microcirculation in patients with peripheral arterial occlusive disease (PAOD) might be affected by prostaglandin E1 (PGE1). The purpose of this study was to investigate local skin perfusion at the forefoot and toe of PAOD patients during different modes of administration of PGE1. PATIENTS AND METHODS: In 17 patients with severe PAOD local intradermal haemoglobin oxygen saturation (SHB) and dermal vascular reserve capacity, transcutaneous oxygen pressure (tcPO2) and laser Doppler flux (LDF) were determined during intra-arterial (1.5 ng/kg body weight/min) and intravenous (6 ng/kg body weight/min) infusion of PGE1. RESULTS: SHB significantly increased at both locations during intravenous PGE1; intra-arterial administration significantly increased SHB in the skin of the forefoot only. Reserve capacity increased during intravenous administration and was markedly reduced during intra-arterial infusion. No significant changes were found regarding tcPO2 and LDF. CONCLUSIONS: These data suggest different therapeutic mechanisms for intra-arterial and intravenous administered of PGE1.

Aged↗
PubMed1997

Biochemical evidence for impaired nitric oxide synthesis in patients with peripheral arterial occlusive disease.

BACKGROUND: We studied urinary nitrate and cGMP excretion rates, indices of systemic NO formation, and plasma concentrations of L-arginine and the endogenous NO synthase inhibitor asymmetrical dimethylarginine (ADMA) and its inactive stereoisomer, symmetrical dimethylarginine, in 77 patients with peripheral arterial occlusive disease (PAOD) in Fontaine stages IIb through IV and in 47 young and 37 elderly healthy control subjects. METHODS AND RESULTS: Urinary nitrate excretion was 182.0+/-11.4 micromol/mmol creatinine and cGMP excretion was 186.2+/-13.0 nmol/mmol creatinine in young healthy control subjects. In elderly control subjects, both excretion rates were slightly lower (nitrate, 156.0+/-7.8 micromol/mmol creatinine; cGMP, 150.0+/-8.3 nmol/mmol creatinine; P=NS). In PAOD patients, there was a significant, progressive reduction of urinary nitrate (IIb, 138.4+/-11.9; III, 128.6+/-11.3; and IV, 91.9+/-8.0 micromol/mmol creatinine; P<.05) and cGMP (IIb, 139.9+/-25.2; III, 115.6+/-13.1; and IV, 76.9+/-7.9 nmol/mmol creatinine; P<.05) excretion rates related to the Fontaine stage of PAOD. These changes were independent of changes in renal excretory function. Plasma L-arginine concentrations were not significantly different between the groups, but ADMA concentrations were elevated in PAOD patients (young control subjects, 1.25+/-0.11; elderly control subjects, 1.01+/-0.05 micromol/L; IIb, 2.62+/-0.24; III, 3.06+/-0.48; and IV, 3.49+/-0.26 micromol/L; P<.05 for PAOD versus control subjects). There was a significant linear correlation between urinary nitrate and cGMP excretion rates and a significant negative linear correlation between plasma ADMA concentrations and urinary nitrate excretion. CONCLUSIONS: In PAOD patients, there is a progressive reduction in urinary nitrate and cGMP excretion rates, which may be caused in part by accumulation of ADMA, an endogenous inhibitor of NO synthase.

Adult↗
PubMed1997

Dose-related effect of intravenous L-arginine on muscular blood flow of the calf in patients with peripheral vascular disease: a H215O positron emission tomography study.

1. Endothelium-derived nitric oxide (NO) contributes to the regulation of vascular tone and blood pressure. Infusion of L-arginine produces systemic vasodilatation via stimulation of endogenous NO formation. Vasodilatation is accompanied by an increase in peripheral arterial blood flow. However, it is not known whether capillary nutritive blood flow increases as well. The time course and dose-response pattern of this effect remain to be elucidated. 2. Two groups of ten patients with peripheral vascular disease (PVD) received an intravenous infusion of 8 g or 30 g of L-arginine over a period of 40 min. Blood pressure and heart rate were monitored non-invasively. Muscular blood flow (MBF) of the calf was determined at 0, 20, 40, 60, 80 min by positron emission tomography with H215O as flow tracer. Plasma L-arginine and cyclic GMP (cGMP) levels were determined at the same time points. 3. L-arginine induced a dose-related decrease in blood pressure during the infusion period. MBF and plasma cGMP levels during and after the infusion of 8 g of L-arginine did not change significantly. In the patients receiving 30 g of L-arginine, MBF was enhanced significantly from 1.56 +/- 0.14 to 2.09 +/- 0.21 ml min-1 100 ml-1 at 40 min and 2.23 +/- 0.15 ml min-1 100 ml-1 after 80 min (+43.0%). The increase in MBF was paralleled by an increase in plasma cGMP from 4789.8 +/- 392.2 nmol/l at baseline to 9223.2 +/- 1233.6 nmol/l at 40 min. 4. We conclude that intravenous L-arginine enhances nutritive capillary MBF in patients with PVD via the NO-cGMP pathway in a dose-related manner. This effect might be therapeutically beneficial in patients with PVD.

Aged↗
PubMed1997

Treatment of primary Raynaud's syndrome with traditional Chinese acupuncture.

OBJECTIVE: Evaluation of the effects of a standardized acupuncture treatment in primary Raynaud's syndrome. DESIGN: A controlled randomized prospective study. SETTING: A winter period of 23 weeks, angiological clinic of Hannover Medical School. SUBJECTS: Thirty-three patients with primary Raynaud's syndrome (16 control, 17 treatment). INTERVENTIONS: The patients of the treatment group were given seven acupuncture treatments during the weeks 10 and 11 of the observation period. MAIN OUTCOME MEASURES: All patients kept a diary throughout the entire observation period noting daily frequency, duration and severity of their vasospastic attacks. A local cooling test combined with nailfold capillaroscopy was performed for all patients at baseline (week 1) and in weeks 12 and 23, recording flowstop reactions of the nailfold capillaries. RESULTS: The treated patients showed a significant decrease in the frequency of attacks from 1.4 day-1 to 0.6 day-1, P < 0.01 (control 1.6 to 1.2, P = 0.08). The overall reduction of attacks was 63% (control 27%, P = 0.03). The mean duration of the capillary flowstop reaction decreased from 71 to 24 s (week 1 vs. week 12, P = 0.001) and 38 s (week 1 vs. week 23, P = 0.02) respectively. In the control group the changes were not significant. CONCLUSIONS: These findings suggest that traditional Chinese acupuncture is a reasonable alternative in treating patients with primary Raynaud's syndrome.

Acupuncture Therapy↗
PubMed1997

Ten strategies for creating successful managed care relationships.

Among the many customers providers serve are managed care organizations. The strategic relationships providers develop with these payers greatly influence the long-term success of both organizations. Providers can implement 10 strategies to improve their managed care relationships: focusing on contracting with selected managed care organizations, fostering positive relationships, coordinating contract participation, establishing communication links, educating providers about managed care, providing high-quality customer service; understanding operating costs, demonstrating value, maintaining flexibility, and pursuing alternative competitive relationships with caution. At the same time, managed care organizations can implement the same strategies to develop win/win relationships with providers.

Communication↗
PubMed1997

Oxygen-15-water PET assessment of muscular blood flow in peripheral vascular disease.

UNLABELLED: To assess quantitatively regional nutritive muscular blood flow in patients with peripheral vascular disease (PVD), we evaluated the utility of PET with 15O-water. METHODS: Eight healthy volunteers and 16 patients with angiographically proven PVD were studied. Regional blood flow of the calf was measured with 15O-water PET during rest, after intra-arterial infusion of prostaglandin E1 and during ergometry. The studies were quantified using a one tissue compartment model. RESULTS: Normalized mean tracer uptake from 15-60 sec correlated closely (r = 0.98) with absolute blood flow. Scan times longer than 90 sec were required to determine blood flow reliably. The flow values were overestimated by 2% if arterial blood volume was neglected or if the input function delay was corrected globally for parametric imaging. Mean blood flow of calf muscles at rest did not differ significantly between patients (0.017 +/- 0.006 ml/min/ml) and control subjects (0.018 +/- 0.010 ml/min/ml). In PVD patients, blood flow increased by 100% after intra-arterial infusion of PGE1 in the respective leg. In the control subjects, average flow increased by a factor of six during exercise. The increase was more pronounced in the extensor muscles (0.182 +/- 0.031 ml/min/ml) than in flexor muscles (0.121 +/- 0.045 ml/min/ml). Due to the specific type of ergometry, superficial flexors exhibited higher flow values than the profound ones. CONCLUSION: PET with 15O-water enables reliable determination of regional nutritive skeletal muscle blood flow for research and clinical applications in patients with PVD.

Adult↗
PubMed1997

Non-invasive determination of dermal hemoglobin oxygenation and concentration in patients with peripheral arterial occlusive disease.

BACKGROUND: Oxygen saturation (SHB) and concentration (CHB) of dermal hemoglobin are important parameters for the supply of the skin. They may be non-invasively assessed by means of reflection photometry as hemoglobin is predominantly contributing to the skin reflection spectrum. METHODS AND RESULTS: Dermal reflection spectra from the middle of the forefoot and from the tip of the toe of 20 healthy subjects and 61 patients suffering from peripheral arterial occlusive disease (PAOD) were recorded and compared to transcutaneous oxygen pressure (tcPO2). SHB, and tcPO2 were significantly higher in controls: compared to patients (ankle pressure (AP) > 50 mmHg) SHB in the skin of the forefoot was 63.8 vs. 54.5% (p < 0.05), CHB was 0.89 vs. 0.62 aU (p < 0.01). In the great toe SHB was 92.9 vs. 59.9% (p < 0.001), CHB was 2.21 vs. 0.92 aU (p < 0.001). Heating the skin of the forefoot to 44 degrees C yields local dermal vascular reserve capacity: SHB and CHB increased in all healthy subjects (96.4%; 1.44 aU, respectively). SHB decreased at the forefoot in 14 and at the toe in 18 of 21 patients with AP < 50 mmHg. At the toe decrease was found in 50 of 61 patients (sensitivity 82%, specificity 100%). CONCLUSIONS: Local vascular reserve capacity of dermal perfusion is reduced in patients with PAOD, depending on AP. It should be determined preferably in patients with severe PAOD.

Adult↗
PubMed1996

L-arginine induces nitric oxide-dependent vasodilation in patients with critical limb ischemia. A randomized, controlled study.

BACKGROUND: L-Arginine is the precursor of endogenous nitric oxide (NO), which is a potent vasodilator acting via the intracellular second-messenger cGMP. In healthy humans, L-arginine induces peripheral vasodilation and inhibits platelet aggregation due to an increased NO production. Prostaglandin E1 (PGE1) induces peripheral vasodilation via stimulating prostacyclin receptors. METHODS AND RESULTS: We investigated the effects of one intravenous infusion of L-arginine (30 g, 60 minutes) or PGE1 (40 microgram, 60 minutes) versus those of placebo (150 mL 0.9% saline, 60 minutes) on blood pressure, peripheral hemodynamics, and urinary NO3- and cGMP excretion rates in patients with critical limb ischemia (peripheral arterial occlusive disease stages Fontaine III or IV). Blood flow in the femoral artery was significantly increased by L-arginine (+42.3 +/- 7.9%, P<.05) and by PGE1 (+31.0 +/- 10.2%, P<.05) but not by placebo (+4.3 +/- 13.0%, P=NS). Urinary NO3- excretion increased by 131.8 +/- 39.5% after L-arginine (P<.05) but only by 32.3 +/- 17.2% after PGE1 (P=NS). Urinary cGMP excretion increased by 198.7 +/- 84.9% after L-arginine (P<.05) and by 94.2 +/- 58.8% after PGE1 (P=NS). Both urinary index metabolites were unchanged by placebo. CONCLUSIONS: We conclude that intravenous L-arginine induces NO-dependent peripheral vasodilation in patients with critical limb ischemia. These effects are paralleled by increased urinary NO3- and cGMP excretion, indicating an enhanced systemic NO production. Increased urinary NO3- excretion may be a sum effect of NO synthase substrate provision (L-arginine) and increased shear stress (PGE1 and L-arginine).

Aged↗
PubMed1996

A new method for the assessment of tissue hemoglobin oxygenation in patients with chronic venous insufficiency.

Venous incompetence often leads to ulceration of the skin of the lower limb due to a disturbance of skin microcirculation. We investigated 10 healthy subjects and 18 patients with chronic venous insufficiency by means of a fast scanning reflection photometer and determined noninvasively the hemoglobin oxygen saturation (S(HB)) and the relative concentration of hemoglobin (C(HB)) in the skin of the forefoot and at the calf, 10 cm proximal of the inner malleolus during positional changes. In supine position no significant differences were found. During sitting and standing S(HB) dropped and was significantly lower in patients at both locations (calf, standing, patients 22.2 +/- 10.6% vs controls 48.2 +/- 13.5%, P < 0.001). C(HB) increased in patients during standing from 0.71 to 2.13 +/- 0.33 aU (in controls from 0.69 to 1.49 +/- 0.28 aU, P < 0.001). Activation of the muscle pump decreased C(HB) and increased S(HB) in patients and in controls. After the movements were stopped, S(HB) decreased again and fell to the initial low values eight times faster in patients (7.4 +/- 5.3 vs 57.5 +/- 19.6 sec, P < 0.001). C(HB) increased four times faster in patients (7.2 +/- 6.1 vs 29.9 +/- 13.6 sec). In sitting and standing positions hemoglobin oxygenation in the skin of the lower limb was markedly reduced in patients, but normal perfusion conditions were restored in supine position, indicating reversibility of the changes. Reflection oxymetry seems a valuable tool for the assessment of chronic venous insufficiency. The substantially reduced oxygenation of dermal hemoglobin in standing patients may contribute to the development of venous ulcers.

Adult↗
PubMed1996

Orthostatic vasoconstrictor response in patients with occlusive arterial disease assessed by laser Doppler flux and transcutaneous oximetry.

Posturally induced microvascular constriction normally causes a decrease of transcutaneous oxygen pressure (tcPO2) and laser Doppler flux (LDF) measured on the forefoot at 37 degrees C. The authors used both methods to assess the vasoconstrictor response (VCR) in 31 patients with various degrees of peripheral arterial occlusive disease (PAOD) and analyzed factors that could have influenced the response. Disturbed VCR was indicated by a signal increase following leg dependency, which occurred significantly more often in tcPO2 than in LDF measurements (69% vs 32%, P < 0.001). Correspondingly the median sitting/supine ratio was 2.4 for tcPO2 and 0.7 for LDF (P < 0.0001). Age and clinical stage had no influence on the VCR. With ankle artery pressures below 50 mmHg an increase of LDF was more probable. TcPO2 predominantly increased with ankle artery pressure up to 100 mmHg, though the sitting/supine ratio of tcPO2 was correlated with ankle artery pressure. In nondiabetics the response of tcPO2 but not of LDF was influenced by the values at rest. Differences between the two methods may be explained in part by their different sample volumes. The authors assume that tcPO2 is predominantly monitoring a local myogenic response while LDF is reflecting venoarteriolar response.

Adult↗
PubMed1996

Hypothenar hammer syndrome successfully managed with intravenous prostaglandin E1 and heparin and with correction of the thrombogenic risk profile. A case report.

A fifty-one-year-old man presented with a history, symptoms, and clinical findings typical of a hypothenar hammer syndrome in his dominant hand. A thrombotic obstruction in the distal section of the ulnar artery with multiple downstream occlusions of proper digital arteries were documented angiographically. Coexistence of additional cardiovascular risk factors (smoking-induced polycythemia, obesity, hypercholesterolemia, and hypertension) was identified. Conservative management with intravenous heparin and prostaglandin E1 together with measures directed at controlling the additional risk factors (repeated venesection, immediate smoking cessation, and low-lipid diet) resulted in a striking clinical and angiographic improvement of the digital perfusion, without resort to interventional measures or thrombolysis.

Alprostadil↗
PubMed1996

Untreated arteriovenous fistula after World War II trauma.

A 76-year-old-patient with severe congestive heart failure due to femoral arteriovenous fistula (AVF) after World War II trauma is presented. He was admitted to our clinic because of increasing dyspnea and vertigo during the last years. Moreover he suffered from chronic venous insufficiency on the lower limb distal of the fistula. History revealed a bullet trauma sustained 50 years ago in 1945 while riding on a train that was taken under fire. In 1973 diagnosis of traumatic AVF was first established by arteriography but the patient did not undergo surgical repair. Actual diagnostic procedure included colour Doppler imaging, chest x-ray, and echocardiography. The patient refused invasive treatment, but drug therapy of congestive heart failure was accepted.

Aged↗
PubMed1996

Thrombosis of the terminal aorta, deep vein thrombosis, recurrent fetal loss, and antiphospholipid antibodies. Case report.

The antiphospholipid syndrome (APS) consists clinically of both arterial and venous thrombosis, recurrent fetal loss and thrombocytopenia associated with antiphospholipid antibodies (aPL). Most of these patients were initially found to suffer from systemic lupus erythematosus (SLE). There is an increasing group of patients who exhibit antiphospholipid antibodies and thrombotic complications without clinical features of SLE or related autoimmune disease termed primary antiphospholipid syndrome (PAPS). The case of a 29-year-old woman with thrombosis of the terminal aorta and deep vein thrombosis, recurrent fetal loss, antiphospholipid antibodies and serological support for an underlying connective tissue disease, probably preclinical SLE is reported.

Abortion, Habitual↗
PubMed1995

[How often is thrombolytic therapy of deep pelvic-leg venous thrombosis indicated?].

BACKGROUND: For patients with deep vein thrombosis new thrombolytic regimes are being proposed and demand evaluation in controlled studies. We tested prospectively, how many patients in internal medicine are candidates for thrombolysis. PATIENTS AND METHODS: All available patients with the diagnosis of deep vein thrombosis (DVT) in lower extremities who were admitted to the service of internal medicine in a medium-sized hospital during one year were prospectively evaluated for the indication of fibrinolysis therapy according to the established criteria. RESULTS: A total of 62 patients were enrolled. Fibrinolysis was not proposed in 25 patients aged over 70 years nor in another 9 patients in whom the thrombosis was restricted to calf veins. Nine additional cases had a recurrence of DVT (n = 4) or a history of more than 14 days. Among the remaining 19 patients, fibrinolysis was not performed in 11 because of advanced malignomas (n =4) or other diseases (n = 3) with limited life expectance, enhanced probability of haemorrhage (n = 3) and obvious non-compliance (n = 1). Eight patients were offered thrombolytic therapy, but 5 of them denied consent after being comprehensively informed. CONCLUSION: Obviously by far most of patients admitted to internal medicine for DVT are candidates for standard heparin therapy only.

Adult↗