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Biomedical subjects

B Lindblad

Publications and source records attributed to B Lindblad.

At least 109 records · Page 6Linked to original sources
PubMed1992

Effect on primary haemostasis of prophylactic regimens of low molecular weight heparin, unfractionated heparin, dextran and their combinations. An animal experimental study.

The aim of the study was to determine whether an impairment of the haemostasis could be observed experimentally when thromboprophylactic substances, which act differently on the haemostatic mechanism, were given single or in combination in prophylactic doses. In 36 rabbits we measured the primary haemostatic plug formation time (PHT), rebleedings and total haemostatic plug formation time (THT) after transection of venules and arterioles using an intravital microscope. We combined unfractionated heparin (UH) and low molecular weight heparin (LMWH) in low dose with either dextran 70 or polygeline (placebo volume expander) in a randomized double-dummy set up. In the placebo group (NaCl and polygeline) the median PHT was 55 and 101 seconds for arterioles and venules respectively, which are well-comparable to earlier results from our group. Most prolonged PHT and THT for arterioles were seen for dextran+NaCl, actually less prolongation was seen for UH+dextran. We did not observe any differences, except for a prolongation of THT for venules in rabbits given dextran+NaCl (p less than 0.05). Thus, in thromboprophylactic doses used, there does not seem to be an impaired or additive effect between heparins and dextran 70 in primary haemostasis in rabbits.

Animals↗
PubMed1992

Preoperative assessment of the risk for cardiac death following thrombo-embolectomy for acute lower limb ischaemia.

Cardiac monitoring and the selective use of initial non-operative management is reported to reduce the high mortality rate in patients with acute lower limb ischaemia. Early estimation, prior to selection of initial therapy, of the risk for intraoperative or postoperative cardiac death following thrombo-embolectomy is therefore important. The aim of this prospective multi-centre study was to develop a simple and clinically useful index for assessment of the risk of post-operative cardiac death. Patients judged to need thrombo-embolectomy for acute lower limb ischaemia were evaluated on admission for routine clinical, cardiac and limb ischaemia parameters that could be related to cardiac function and these parameters compared to postoperative cardiac outcome. Sixteen per cent of the 117 patients died from intraoperative or postoperative cardiac complications. Analysis revealed five admission parameters that significantly and independently predicted a high risk for cardiac death: mean arterial blood pressure below 90 mmHg, clinical sign(s) of cardiac decompensation, ischaemia affecting the thigh, haemoglobin concentration exceeding 140 gl-1, and a history of a myocardial infarction in the previous 4 weeks. Definition of risk points for each risk factor allowed a simple classification of each patient into one of three significantly different cardiac risk classes with cardiac death rates of 6 +/- 3%, 27 +/- 8% and 75 +/- 16%, respectively. More than two thirds of the patients belonged to the low risk group. The described risk index provides a tool for preoperative assessment of the cardiac death risk associated with early thrombo-embolectomy in patients with acute lower limb ischaemia.

Aged↗
PubMed1992

The acute thrombogenicity of an infection-resistant rifampicin-soaked Dacron graft: an experimental study in sheep.

Every effort to reduce synthetic graft infection is welcome and when designing antibiotic-bonded grafts it is important not to increase graft thrombogenicity. In order to study the acute thrombogenicity of rifampicin-soaked gelatin-sealed Dacron grafts compared with untreated gelatin-sealed Dacron grafts, an experimental carotid artery sheep model was used. Twenty sheep were anaesthetised and 7-cm-long 5-mm-wide externally supported gelatin-sealed knitted Dacron grafts were sutured end to end into each carotid artery after excising a portion of that vessel. Test grafts had previously been immersed for 15 min in a rifampicin solution (1 mg ml-1) while control grafts were immersed in physiological saline for 15 min. There were two groups with 10 sheep in each. In one group the blood flow through the grafts was unrestricted but in the second the flow was restricted to 25 ml min-1. Platelets from sheep labelled with 111In and sheep fibrinogen labelled with 125I were injected intravenously. The isotope activities were continuously measured proximally and distally over the grafts for 4 h. With unrestricted flow 4 out of 10 rifampicin-soaked grafts occluded compared with 2 out of 10 control grafts (N.S.). Time to occlusion, thrombus weight, platelet and fibrinogen activity did not differ. In the restricted flow group 9 out of 10 rifampicin-soaked grafts occluded compared with 6 out of 10 control grafts (N.S.). The time to occlusion did not differ. The thrombus weight in the rifampicin group was significantly higher compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The effect of a combined thromboxane receptor- and synthesis-antagonist on platelet, fibrinogen and leucocyte uptake in ePTFE grafts: an experimental study in sheep.

Arterial expanded polytetrafluoroethylene (ePTFE) grafts were interpositioned in the common carotid arteries of 20 adult sheep. This model was used to study the effect of a combined thromboxane receptor- and synthesis-antagonist, Ridogrel (R 68070), on acute graft patency and platelet, fibrinogen and leucocyte uptake. The animals were randomised to treatment (n = 10) or control groups (n = 10). Treatment was given as an intravenous injection with Ridogrel of 8 mg kg body weight-1. The flow in one of the two inserted grafts was restricted to 25 ml min-1. Autologous 111In-labelled platelets, 125I-labelled fibrinogen and 99m-Tc-labelled leucocytes were injected intravenously and the radioactivity over the vessels measured before and after graft insertion using the gamma scintillation technique. After graft insertion the measurements continued for 4 h at two separate points over the proximal and distal anastomosis areas. In the treatment group six out of 10 grafts with restricted flow remained patent compared with nine out of 10 grafts with flow reduction in the control group (N.S.). The median thrombus weights did not differ significantly. There was no difference in the platelet and fibrinogen activities at the proximal anastomosis but distally the animals receiving treatment had a significant reduction during the first 2 h of the experiment. The leucocyte activity in the treatment group compared to the control group did not differ proximally but distally the activity was significantly higher during the last 3 h of the experiment. In the group with unrestricted flow all grafts in both groups remained patent. The thrombus weight was significantly lower in the treatment group compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Prostacyclin is produced from endothelial cell-seeded grafts: an experimental study in sheep.

Endothelial cell seeding might be of value in reducing the thrombogenicity of small-diameter vascular grafts. We investigated the capacity of endothelial cell-seeded grafts to produce prostacyclin and compared this with that of the unseeded graft as well as the native artery. Twelve sheep were operated on with carotid interposition of externally supported knitted dacron grafts. On one side of the neck the graft was seeded with endothelial cells, enzymatically harvested from the left jugular vein. After 3 weeks, three out of 12 seeded grafts, and one out of 12 unseeded grafts were occluded (N.S.). After excision, the grafts were mounted and perfused ex vivo for five 15-min periods. During the last period, arachidonic acid (4 micrograms/ml) was added to the perfusate. The resected carotid artery was used as a control. Prostacyclin was determined as the stable degradation product 6-keto-PGF1 alpha using radio-immunoassay, and expressed as pg mm-2 luminal surface. The native artery had a significantly higher release of prostacyclin than the seeded graft, which in turn had a significantly higher release than the unseeded graft. Histological examination showed weakly positive staining for factor VIII-related antigen on the luminal surface of seeded grafts. Scanning electron microscopy showed endothelial cells with typical endothelial tufts and was evaluated blindly from 10 areas of each graft. The extent of endothelial cell coverage was evaluated and scored from 0 to 2.5. The median score for the unseeded grafts was 0.3 and for the seeded grafts 1.5 (p = 0.008). Prostacyclin production was higher in seeded than unseeded grafts, but did not influence patency in this model.

Animals↗
PubMed1992

A prospective study of the incidence of deep-vein thrombosis within a defined urban population.

In a prospective study all positive phlebographies within the well-defined population of the city of Malmö, Sweden, during 1987 were studied in order to determine the incidence of deep venous thrombosis (DVT). Epidemiological data were analysed for the detection of patient groups at increased risk of DVT. The incidence was found to be equal for both sexes, i.e. 1.6 per 1000 inhabitants a year. Risk factors were found to be in accordance with earlier studies. The median age for men was 66 years, compared to 72 years for women. At diagnosis of DVT, 19% of subjects had a known malignancy and within 1 year 5% (19 cases) developed a new malignancy. Of the men, 29% had postoperative or post-traumatic (fracture) DVT, compared to 46% of the women. Fewer patients with DVT than expected (39%) belonged to blood group 0 (31%) (P less than 0.005). Pulmonary embolism (PE) was clinically suspected in only 5% of cases, and diagnosis was verified scintigraphically in 2% of cases. None of these died of PE, but of 6 patients who were found to have PE at autopsy, four died about 4 weeks after the DVT was diagnosed.

Adolescent↗
PubMed1992

Low molecular weight heparin for thromboprophylaxis and epidural/spinal anaesthesia--is there a risk?

This article reviews the problem of bleeding in connection with epidural/spinal anaesthesia, with special emphasis on the use of low molecular weight heparins for thromboprophylaxis. There are methodological difficulties to studying the problem in a scientifically correct way because of the rarity of the complication. However, from the data in the literature there are no indications of an increased risk in using the combination of low molecular weight heparin in prophylactic doses and epidural/spinal anaesthesia. So far, there is only a single case report, of spinal haematoma, although low molecular weight heparins have been used in combination with epidural/spinal anaesthesia in at least 1,000,000 patients. In controlled studies, at least 10,000 patients have been given the combination without complications.

Anesthesia, Epidural↗
PubMed1992

Time-related effects of heparin sulfate on regional and systemic anticoagulation.

Optimal timing of vascular clamping to anticoagulation during cardiovascular surgical procedures is poorly defined. This study uses a canine model to determine the effectiveness of three different methods of heparin administration. Heparin sulfate (150 IU/kg) was administered by: injection into the jugular vein 5 minutes before infrarenal aortic clamping (Group 1), injection into the terminal aorta immediately after infrarenal aortic clamping (Group 2), and injection into the jugular vein immediately after infrarenal aortic clamping (Group 3). Thrombin clotting times and partial thromboplastin times were measured in venous blood from the upper and lower extremities before (baseline) heparin administration, and 1, 3, and 5 minutes following heparin administration. Activated clotting times were assessed in lower extremity blood at baseline, and at 1 and 5 minutes after heparin injection. Significant differences existed between groups in both upper and lower extremities. Systemic anticoagulation occurred within 1 minute after intravenous heparin administration in Groups 1 and 2 in the lower extremity, and Groups 1 and 3 in the upper extremity. Delayed anticoagulation in the lower extremity was noted with systemic injection after aortic clamping in Group 3, and after regional intra-aortic administration in the upper extremity of Group 2 subjects. Complete anticoagulation was noted by 5 minutes in all groups in both the upper and lower extremities. These results suggest that the safe time period between heparin administration and vascular clamping varies with the route and the timing of its administration. Intravenous administration prior to aortic cross-clamping provided adequate anticoagulation in this canine model in both the upper and lower extremity blood after 1 minute of heparin circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Collagen and gelatin-impregnated vascular grafts--is their thrombogenicity enhanced? An experimental study.

The early thrombogenicity of dacron vascular grafts with and without impregnation with collagen (n = 7) or gelatin (n = 7) was evaluated in a sheep carotid artery interposition model. Autologous platelets were labelled with 32P and reinjected. Flow was reduced to 25 ml/min to mimic a situation with poor run-off and the graft thrombogenicity was studied for 4 hours. The results showed no difference as regards patency, thrombus-free surface, or uptake of 32P-labelled platelets between collagen- or gelatin-impregnated grafts and their parent dacron grafts. Thus, no difference in early graft thrombogenicity could be documented.

Animals↗
PubMed1991

Incidence of venous thromboembolism verified by necropsy over 30 years.

OBJECTIVE: To determine the incidence of venous thromboembolism in all necropsy reports over 30 years. DESIGN: Study of all necropsies in one hospital in 1987 and longitudinal analysis of results of necropsy in 1957, 1964, 1975, and 1987. SETTING: Departments of general surgery, infectious diseases, internal medicine, oncology, and orthopaedics in a Swedish general hospital. MAIN OUTCOME MEASURE: Number of cases of venous thromboembolism. RESULTS: About a third of all necropsies showed venous thromboembolism. In 1987, 260 of 347 necropsies showing venous thromboembolism found pulmonary embolism, of which 93 were classified as fatal, 90 as contributory, and 77 as incidental. Only 21 contributory or fatal postoperative pulmonary emboli were seen. In only 106 of 260 patients with pulmonary embolism did routine necropsy not show the source of embolism. Calf veins were not routinely examined. Deep venous thrombosis was seen in 239 patients in 1987. The incidence of venous thromboembolism in the four years studied was remarkably stable except in the department of orthopaedics, where the proportion fell from 60.7% in 1975 to 32.2% in 1987 (p less than 0.05), although there were only a few patients. CONCLUSIONS: The overall incidence of venous thromboembolism has not changed over 30 years. During this period the proportion of the population aged over 65 has doubled, and this may have masked the beneficial effects of prophylaxis and early mobilisation. Prevalences corrected for age are needed.

Aged↗
PubMed1991

Autopsy-verified pulmonary embolism in a surgical department: analysis of the period from 1951 to 1988.

A retrospective analysis was undertaken of all surgical patients in Malmö, Sweden, during the period from 1951 to 1988 in whom pulmonary emboli were found at autopsy. The analysis included a comparison with the earlier analysed and reported time period from 1951 to 1980. A continued high frequency of pulmonary embolism at autopsy was seen during the 1980s (20.3 per cent of deaths, 31.7 per cent of autopsies). Of the 391 autopsy-verified pulmonary emboli found between 1981 and 1988, 113 (28.9 per cent) were considered fatal, 104 (26.6 per cent) contributed to death and 174 (44.5 per cent) were incidental. Few patients had symptomatic deep vein thrombosis or pulmonary embolism before death. The overall frequency of major pulmonary embolism in surgical patients remained unchanged (0.3 per cent). The frequency of major postoperative pulmonary embolism showed an increase during the 1950s and 1960s (maximum 0.4 per cent) but a decrease in the last 5-year period of the 1970s (0.3 per cent), which has earlier been reported upon. This decrease continued during the 1980s (0.2 per cent) (P less than 0.05). An increase was found in the number of patients operated on who had autopsy-proven pulmonary embolism and who received thromboprophylaxis. Pulmonary embolism continues to be a major cause of death in surgical patients; however, postoperative major pulmonary embolism has shown a reduction in the last 15-year period.

Adult↗
PubMed1991

The effect of a thromboxane receptor antagonist on acute ePTFE arterial graft thrombogenicity--an experimental study in sheep.

ePTFE interposition grafts in the common carotid arteries of 16 adult sheep were used to study the effect of a thromboxane receptor antagonist. Vapiprost (GR 32191, Glaxo research group, London, UK). After insertion of the grafts the sheep were randomised to treatment (n = 8) or control (n = 8). Treatment was given as an intravenous injection with GR 32191 of 1 mg/kg body weight. The flow in one of the two inserted grafts was restricted from normal (190 ml/min) to 25 ml/min. Autologous 111-In labelled platelets and human 125-I labelled fibrinogen were injected intravenously. The radioactivity over each graft was measured for 4 h at two separate points with a gamma scintillation technique. Due to technical complications immediately before the start of the measurements one sheep in each group was excluded from the study. In the treated group three out of seven grafts with restricted flow occluded compared to all seven grafts with a flow reduction in the control group (p less than 0.05). The grafts with unrestricted flow occluded in two of seven in both groups. In the open grafts with unrestricted flow the fibrinogen activity was significantly reduced in the treated group compared to the control group. The platelet activity was not significantly reduced. It is concluded that GR 32191 significantly reduced the fibrinogen uptake as well as graft occlusions of ePTFE grafts in a low flow situation.

Acute Disease↗
PubMed1991

Abdominal aortic aneurysm with perianeurysmal fibrosis: experience from 11 Swedish vascular centers.

Case records of 2026 patients operated on because of abdominal aortic aneurysms from 11 Swedish Vascular Centers were reviewed and revealed 98 cases (4.8%) of inflammatory abdominal aortic aneurysm. Also included in this case-control study was an analysis of a randomized group of 82 patients from the same centers who had noninflammatory abdominal aortic aneurysms. Four inflammatory aneurysms were ruptured, compared with 16 in the noninflammatory group (p less than 0.01). A higher proportion of patients with inflammatory abdominal aortic aneurysms had symptoms that led to radiographic investigations. The median erythrocyte sedimentation rate was 39 mm versus 19 mm (26% of patients with inflammatory abdominal aortic aneurysms had erythrocyte sedimentation rates greater than 50 mm; p less than 0.001), and the serum creatinine level was increased in 27 and 8 patients (p less than 0.01) in the inflammatory and noninflammatory groups, respectively. Preoperative investigations revealed ureteral obstruction in 19 patients with inflammatory abdominal aortic aneurysms, of whom 12 had preoperative nephrostomy or ureteral catheter placement. At operation, 20 additional patients exhibited fibrosis around one or both ureters. Although ureterolysis was performed in 19 patients, preoperative and postoperative creatinine levels did not differ between these patients and the conservatively treated ones. Duration of surgery (215 vs 218 minutes), intraoperative blood loss (2085 vs 2400 ml) and complications did not differ significantly between the groups. Overall operative (30-day) mortality was equal (11% vs 12%) but was increased for patients undergoing elective surgery for inflammatory abdominal aortic aneurysms (9% vs 0%; p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗