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Biomedical subjects

L Norgren

Publications and source records attributed to L Norgren.

At least 91 records · Page 5Linked to original sources
PubMed1995

The effect of graduated elastic compression stockings on femoral blood flow velocity during late pregnancy.

The effect on femoral vein flow velocity of graduated compression was studied in ten women during late pregnancy. The maternal heart rate increased significantly when the position was changed from supine to vertical. This orthostatic increase was significantly reduced when graduated compression exerting 25 mmHg at the ankle level was applied. Closely related to these findings was a significantly decreased femoral vein flow velocity in the vertical position, less pronounced when graduated compression was used. The flow velocity was also significantly higher with compression than without in the standing position. These findings support the use of graduated compression during late pregnancy.

Adult↗
PubMed1995

Vascular injuries in Sweden 1986-1990: the result of an enquiry.

In order to review the management of vascular trauma in Sweden all surgical and orthopedic departments were asked to report retrospectively vascular injuries occurring between 1986 and 1990. There were 294 injuries reported from 55 departments. The majority (approximately 80%) of the injuries were confined to the extremities. In the arms the injuries of the vessels were mostly simple, whereas in the legs they were more complex and correct treatment demanded extensive experience in vascular surgery. No less than 20% of the injuries were iatrogenic and half of them required reconstructive surgery. 55% of the iatrogenic injuries occurred during angiological examinations and treatments. Complex vascular injuries are often combined with fractures and soft tissue damage and required close cooperation between vascular and orthopedic surgeons. Advanced angiological examinations and treatments should only be performed in hospitals with vascular surgery facilities.

Arteries↗
PubMed1995

Metabolic response of blood cells to synthetic graft-materials with special reference to a Fluoromer Passivated Dacron graft. An in vitro study using microcalorimetry.

Microcalorimetry was used to study in vitro the metabolic response from human platelets and leukocytes when incubated with three different synthetic graft-materials. The graft to be studied primarily was Fluoromer Passivated Dacron (FPD) which was compared with ePTFE and with a knitted Teflon graft. A rapid increase in the metabolic activity of platelets was observed, followed by a steady-state for more than one hour, while the platelet metabolism did not differ among the various graft-materials. Leukocytes incubated with FPD showed a high initial metabolism, with a peak after about 15 minutes. After 60 minutes the metabolic response had reached control values. ePTFE and Teflon grafts differed significantly from FPD, without causing any peak metabolic activity. It may be concluded that FPD and ePTFE grafts, as evaluated in vitro, activate platelets to the same extent, while FPD causes a more extensive leukocyte activation. Whether these findings can be interpreted as differences in thrombogenicity and inflammatory responses has not been proven, but seems probable. This in vitro method should make it possible to further study human responses to synthetic materials a method possibly more reliable than animal experiments.

Biocompatible Materials↗
PubMed1994

Vascular surgical audit during a 5-year period. Steering committee on behalf of the Swedish Vascular Registry (Swedvasc).

UNLABELLED: The objective was to explore possible time trends in the indications for peripheral vascular surgery in Sweden. DESIGN: Analysis of data from the Swedvasc vascular registry 1987-1991. SETTING: Routine vascular surgery in university, county and district hospitals within the Swedish public hospital system. The registry is independent of local administration, run by the surgeons themselves and financed by national authorities. MATERIALS: 4950 procedures registered in the 17 original centres 1987-91 and 1892 procedures registered in 16 new centres 1991. CHIEF OUTCOME MEASURES: Distribution of indications, mortality within 30 days and clinical outcome at one year. MAIN RESULTS: During the first 5 years of the registry (1987 to 1991) the proportion of procedures performed for acute ischaemia significantly decreased from 20% to 14.3%. Simultaneously procedures for critical leg ischaemia significantly increased from 24.8 to 30.3%. Changes in the proportions treated for aortic aneurysms, carotid artery stenosis, claudication, vascular access or other indications were less striking or nonsignificant. The 30-day mortality decreased in patients operated on for acute ischaemia but did not change in other groups. The proportion of elective/emergency operation for aortic aneurysm changed from 1.2 to 2.0 leading to a minimal decrease in overall aneurysm mortality. The proportion of patients treated for claudication who were alive and improved at one year changed from 77.2% to 72.9% which was not statistically significant, while the proportion of patients treated for critical ischaemia who were alive with an intact leg after one year increased from 65.2% to 80.2% which was a significant improvement. CONCLUSIONS: Decision making among vascular surgeons in Sweden appears to have improved as proportionally fewer patients are operated on for acute ischaemia, more for critical ischaemia with possibly an improved outcome.

Humans↗
PubMed1994

Iodixanol in femoral arteriography. A randomized, double-blind, phase III, parallel study with iodixanol 270 mg I/ml and iohexol 300 mg I/ml.

Two contrast media, iodixanol (Visipaque, Nycomed) 270 mg I/ml and iohexol (Omnipaque, Nycomed) 300 mg I/ml, were compared in femoral arteriography, in 147 patients. Both contrast media were diagnostically effective for use in femoral arteriography, without any significant difference. Pain was reported in connection with injection of iohexol by 36% of the patients, after injection of iodixanol none reported pain. Seventy-two percent of the patients in the iodixanol group reported a sensation of warmth in connection with contrast injection versus 90% in the iohexol group. The average intensity of the warmth was greater with iohexol than with iodixanol. Fourteen percent of patients in the iodixanol group and 1% in the iohexol group reported one or more subjective adverse events.

Aged↗
PubMed1994

To what extent does peripheral vascular disease and hypertension predict renal artery stenosis?

The incidence of renal artery stenosis (RAS) was prospectively evaluated by aortofemoral angiography in 100 patients with peripheral vascular disease (PVD) to find whether RAS was a more common finding in hypertensive than in normotensive patients. For a possible association with RAS, risk factors, clinical and angiographical variables were evaluated. Nephrotoxicity of the contrast medium Iohexol was elucidated. A follow-up of six month was performed in patients with severe stenosis or total occlusion of the renal arteries. Of the 49 patients with a renal artery lesion 26.5% were normotensive and 73.5% hypertensive. Hypertension was significantly correlated to RAS. Reconstructive vascular procedures were during the follow-up performed in 47.3% of the patients with severe RAS or occluded renal arteries, two patients underwent a renal artery revascularization, none of them got a postoperative blood pressure decrease. Hypertension in patients with peripheral vascular disease is predictive for renal artery stenosis and a possible renovascular hypertension should be evaluated. Surgery for renal artery stenosis in peripheral vascular diseased patients should, however, probably be performed firstly to reduce the risk for occlusion. The effect on the blood pressure can not be predicted without a more careful analysis that the blood pressure is renin-dependent. Iohexol showed low nephrotoxicity, also in patients with renal artery disease.

Aged↗
PubMed1994

The role of septic complications in aortic aneurysm surgery.

Out of 229 patients operated due to abdominal aortic aneurysms, 51 (22.3%) had prolonged (> 120 hours) postoperative intensive care stay. The mortality rate in this group was 27% representing 46% of the total mortality. Twenty-five of these 51 patients had postoperative septic complications, meaning positive blood cultures. Clinically wound infections (11), acalculous cholecystitis (9), urinary tract infections (9), septicemia (6), and diffuse peritonitis or abdominal abscess were found (4). Reoperations, time for ventilatory support, incidence of renal failure and dialysis, gastrointestinal complications and mortality were all frequent in patients with septic postoperative complications as compared to those with non-septic complications, the latter mainly of cardiovascular origin. Signs of organ dysfunction should raise a suspicion of a septic complication and prompt insertion of diagnostic procedures and therapeutic interventions are necessary in order to minimize morbidity and mortality.

Abdominal Abscess↗
PubMed1994

Healing characteristics of polymer-coated or collagen-treated Dacron grafts: an experimental porcine study.

The healing characteristics of polymer-coated Dacron grafts with or without heparin-bonding and collagen-coated Dacron grafts are compared with standard knitted Dacron grafts by implanting eight of each graft into pig iliac arteries. The grafts were implanted at random bilaterally with end-to-side anastomoses. The grafts were explanted after 1, 2 and 4 weeks and prepared for histological evaluation by in vivo fixation. Graft segments were investigated by light microscopy, scanning electron microscopy and transmission electron microscopy. The endothelial coverage, intimal thickness and healing characteristics were subjected to one-way analysis of variance. One week after surgery endothelial-like cells appeared close to the anastomoses and after 2 weeks a clear growing endothelial edge was observed in the collagen-coated grafts. After 4 weeks' implantation all grafts were patent and endothelial cells covered the grafts to a various extent. Collagen-coated grafts had significantly greater endothelial cell coverage compared with Dacron and polymer-coated grafts without heparin bonding (P < 0.05). Evaluation by transmission electron microscopy revealed the luminal coverage of the collagen-coated grafts to consist of organized smooth muscle cells and endothelial cells containing Weibel-Palade bodies. The smooth muscle cells in the other grafts were less organized and were covered by endothelial cells to a lesser degree. No differences were noted regarding the inflammatory response of the graft materials and no further positive effects were encountered by the addition of heparin to the polymer coating. The study demonstrates that various coating procedures and surface modulation of knitted Dacron grafts produce a graft which is impervious to blood but still allows tissue incorporation.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1993

The adhesion of labelled neutrophils on synthetic vascular grafts. An experimental porcine study.

The adhesion of neutrophils onto different vascular grafts was studied in vivo in a pig model. In acute experiments autologous 111In-labelled neutrophils were reinfused after end-to-side implantation of 5 cm, 6 mm internal diameter grafts. The dynamic deposition on each graft was determined for 300 min in vivo. Static measurements in vitro concluded the study. The adhesion was greater in Dacron and collagen coated Dacron grafts compared to expanded polytetrafluoroethylene (ePTFE) and to Dacron grafts coated with a polymer. The segmental activity along all the grafts increased towards the distal anastomosis. The results suggest different inflammatory response to various graft materials.

Animals↗
PubMed1993

Acute thrombogenicity and 4 weeks healing properties of a new stretch-ePTFE graft.

Recently a new expanded polytetrafluoroethylene (ePTFE) graft with length compliant characteristics has been developed. The present study compared the acute thrombogenicity and 4 weeks healing characteristics of the stretch ePTFE graft to standard ePTFE grafts in vivo. Grafts of 6 cm length and 8 mm internal diameter were inserted end-to-side into the iliac arteries in pigs. Platelet adhesion was assessed by infusing indium-111-oxine (20 MBq) labelled autologous platelets and dynamically imaging the grafts. Explanted grafts (n = 14) were opened longitudinally and the thrombus-free surface (TFS) and segmental accumulation of platelets were determined. Stretch ePTFE grafts had significantly less platelet deposition when compared to standard ePTFE graft (p < 0.01). The dynamic increase of activity from 10 min after start of measurement was also significantly reduced (p < 0.05) for 170 min as compared to standard ePTFE grafts. TFS was 68 +/- 5% for stretch ePTFE and 37 +/- 5% for standard ePTFE grafts (p < 0.01). After explanation and fixation the grafts were investigated by light microscopy, scanning and transmission electron microscopy. At 1 week after surgery, both kind of grafts were covered by a fibrinous layer containing platelets and leukocytes. After 2 weeks a pseudoendothelial layer was found in the perianastomotic regions. After 4 weeks, two out of four standard ePTFE grafts were occluded due to intimal hyperplasia and subsequent thrombosis in the midportion of the grafts. All stretch ePTFE grafts were patent and covered by a smooth pseudointima. This study thus demonstrates a lower acute thrombogenicity in stretch ePTFE grafts compared to the standard graphs.

Anastomosis, Surgical↗
PubMed1993

Graduated compression stockings in the prevention of deep vein thrombosis in patients with acute myocardial infarction.

Venous volume (venous capacity) of the calf is low in patients with acute myocardial infarction, who also have a high risk of deep vein thrombosis (DVT). The effect of graduated compression stockings on the venous volume and on the incidence of DVT was therefore studied in 80 patients aged 70 years and above with acute myocardial infarction. Graduated compression stockings were randomly fitted to one leg, the other serving as a control, after which the venous volume was measured by strain gauge plethysmography. The incidence of DVT was measured by the 125I fibrinogen uptake test. Venous volume was significantly higher in legs treated with graduated compression stockings compared to control legs. DVT developed in eight control legs but not in any leg treated with graduated compression stockings (P = 0.003). DVT was also significantly more frequent in women compared to men and the majority of DVT developed in legs with very low venous volume values.

Aged↗
PubMed1993

Rebound increase of PAI-1 following local intra-arterial rt-PA infusion, a possible cause of reocclusion.

We studied systemic changes in the plasminogen activating system induced by local intra-arterial infusion of recombinant t-PA (rt-PA) in ten patients with arterial occlusion. The arterial infusion of rt-PA resulted in an immediate increase of t-PA activity and antigen in venous plasma. Concomitantly the plasma was depleted of PAI-1 activity with a moderate decrease of PAI-1 antigen, presumably due to immediate complexing of rt-PA by PAI-1 and gradual elimination of the rt-PA/PAI-1 complex from the circulation. Activation of plasminogen in the circulation was reflected by the occurrence of fibrinogen/fibrin degradation products. This rapid systemic activation of the fibrinolytic system at local intra-arterial administration of rt-PA might be due to the opening of small collaterals or backward flow through open arteries, allowing rt-PA to enter the general circulation. The disappearance of detectable PAI-1 activity during rt-PA infusion was followed by a rebound effect with a significant increase of PAI-1 antigen. As this increase may have contributed to the reocclusion which occurred in four patients, it might be advisable to replace heparin by rt-PA at a lower dosage in the immediate phase following rt-PA infusion.

Aged↗
PubMed1993

Reticuloendothelial system function following acute liver failure induced by 90% hepatectomy in the rat.

Sepsis and bacterial infections are frequent complications of acute liver failure and following major liver resection. The mechanisms underlying this phenomenon are unclear. In this study, RES function and blood clearance of radiolabelled E. coli was immediately impaired following 90% hepatectomy, although the reduction in liver volume resulted in an increase in splenic (temporary) and pulmonary (persisting) uptake. A significant correlation between liver function and host RES function was observed. The uptake capacity of the RES in the liver remnant and spleen did not correlate with subserosal blood flow. The uptake in the brain gradually increased with time, paralleling an increased leakage across the blood-brain barrier. Thus, a significantly impaired RES function resulted from experimental 90% hepatectomy-induced acute liver failure, which might explain the high incidence of septic events in the clinical situation.

Animals↗
PubMed1992

Surgical treatment versus thrombolysis in acute arterial occlusion: a randomised controlled study.

Thrombolytic treatment has been tried in various forms for acute limb ischaemia with varying degrees of success but is also often accompanied by bleeding problems. The present investigation compares the effect of surgical thrombectomy (TE) and thrombolysis (TL) using recombinant tissue plasminogen activator (rt-PA). Twenty patients with a need for intervention owing to ischaemia lasting more than 24 h but less than 14 days were included. Patients randomised to TE were operated under epidural anaesthesia and patients in the TL group received 30 mg rt-PA during a 3 h period through a catheter placed into the thrombus and advanced as lysis was achieved. Thrombectomy resulted in an immediate restitution of blood flow in six out of nine cases, in three cases a bypass procedure was performed, and one of these failed with a resultant amputation. Thrombolysis gave a good primary result in six cases which lasted in four of them. Three had a subsequent percutaneous transluminal angioplasty. Partial lysis was seen in two cases and a further two failed. Five went to surgery with three bypass and two fogarty procedures being necessary. There was no hospital mortality and there were no bleeding complications due to the rt-PA treatment in this series. In 19 out of 20 patients the circulation was re-established. Appropriate handling of acute ischaemic conditions implies the use of both thrombolysis and appropriate surgical procedures, including distal bypass grafts.

Acute Disease↗
PubMed1992

The influence of biliary obstruction and sepsis on reticuloendothelial function in rats.

Obstructive jaundice is frequently associated with septic complications and renal impairment. The present study was performed in order to evaluate reticuloendothelial system (RES) function in obstructive jaundice and the influence of a septic challenge. Male Sprague-Dawley rats were allocated into four groups (laparotomy alone, caecal ligation and puncture (CLP), ligation of the common bile duct (CBD) alone and CBD+CLP, respectively). Mortality, blood clearance and organ distribution of 125I labelled Escherichia coli were determined. Mortality in sepsis (CLP) significantly increased in jaundiced animals (p less than 0.033). Blood clearance of radiolabelled E. coli was significantly impaired in both jaundiced groups. In jaundiced animals, hepatic localisation and renal uptake of E. coli significantly increased (p less than 0.001), while radioactive counts in bile significantly decreased (p less than 0.01). Changes in organ distribution of bacteria did not depend on alterations in blood flow. Thus, RES function was impaired in jaundiced animals and mortality increased in a concomitant septic challenge in jaundiced animals.

Animals↗
PubMed1992

Iodixanol--a new nonionic dimer--in aortofemoral angiography.

In 26 patients iodixanol, a new nonionic dimer, isotonic to blood in all concentrations, was used as contrast medium in aortofemoral angiography. Half of the patients received contrast medium in a concentration of 270 mg I/ml and the other half 320 mg I/ml. The aim of the trial was to evaluate the safety and tolerability of iodixanol and the radiographic efficacy of the two concentrations. The degree of discomfort, adverse events, changes in serum chemistry parameters, and diagnostic information were assessed. There were no changes or trends of clinical importance in serum chemistry parameters. The side effects were mild and consisted mostly of some sensation of warmth of short duration. No other adverse events were seen. The overall radiographic efficacy did not show any significant difference between the two concentrations. This indicates that iodixanol is safe and well tolerated when used in adult femoral angiography.

Adult↗