Deep venous thrombosis in orthopaedic patients. Improving the specificity of diagnosis.
ABSTRACT The diagnosis of deep vein thrombosis after total joint arthroplasty is difficult. The most widely used method of detection is physical examination and selective venography, which are unreliable and expensive even when symptoms and signs are prominent. This study employed computerized strain gauge plethysmography (CSGP) to select symptomatic patients for venography. The incidence of detection by CSGP was increased from 16% to 81.7%. Repeated CSGP also was investigated, but although specificity was further enhanced, it was at the expense of sensitivity. The negative predictive value of the CSGP screening was high and comparable to that of venography and indicates that CSGP is useful in the management of patients with symptoms suggestive of deep vein thrombosis. Computerized strain gauge plethysmography results emphasize the low specificity and poor feasibility of clinical examination and venography. Computerized strain gauge plethysmography is strongly advocated as a selection procedure for invasive venography in total joint arthroplasty patients.
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ABSTRACT: To investigate the incidence of deep vein thrombosis (DVT) among elderly Hong Kong Chinese patients suffering from acute hip fracture and to analyse the risk factors associated with DVT. A total of 100 consecutive Chinese hip fracture patients with a mean age of 80 years were investigated serially using duplex ultrasound scans preoperatively and at 1 week, 3 to 6 weeks, and 3 months postoperatively. No chemoprophylaxis or prophylaxis against DVT was given. 95 patients completed 3 duplex scans during hospitalisation; 5 (5.3%) of them were found to have developed DVT over the ilio-femoral venous segment. Of the 90 patients who had no DVT, 73 were reassessed 3 months after operation; one of them was found to have developed calf DVT. Older patients, chairbound or dependent patients, and patients living in institutions carried a higher risk of developing DVT. This prospective study shows that the incidence of DVT developing after acute hip fracture in Chinese geriatric patients was low. We therefore do not recommend routine chemoprophylaxis for elderly patients with hip fracture.Journal of orthopaedic surgery (Hong Kong) 01/2005; 12(2):178-83.
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ABSTRACT: Strain gauge plethysmography (SGP) is a non-invasive method used in the detection of deep venous thrombosis (DVT). The technique is based on the measurement of calf volume changes in response to venous occlusion by a thigh cuff, the volume changes reflecting the rates of arterial inflow and venous outflow. A numerical model of the blood circulation within the limb and the response of this to a SGP test has been derived, based on treating the different parts of the circulatory system in the leg as resistance and capacitance elements. The simulation results were compared with clinical studies and support the ability of SGP to detect non-occlusive clots of more than 50-60% of the lumen, as well detecting calf vein occlusion. The non-linear behaviour of the venous compliance with intra-luminal pressure appears to be a particularly important factor within the model. In addition, increases in venous tone due to post-operative venospasm were shown to be a potential source of false positive results.Medical & Biological Engineering & Computing 06/2000; 38(3):348-55. · 1.79 Impact Factor
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ABSTRACT: The effect of surgery for femoral neck fracture on lower limb venous blood flow and its relationship to deep vein thrombosis was investigated in 179 patients. Blood flow was measured using strain gauge plethysmography before surgery, in the 1st week after surgery, and at 6 week review. There was a significant reduction in both venous outflow and venous capacitance, affecting both fractured and non-fractured legs but significantly greater in the fractured leg. Venous function remained significantly impaired in both lower limbs 6 weeks after surgery. There was a significant correlation between the reduction in venous function and the development of deep vein thrombosis.Injury 02/2002; 33(1):33-9. · 1.93 Impact Factor