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Indian Journal of Surgery, Vol. 65, No. 2, March-April, 2003, pp. 159-162 Deep vein thrombosis in Indian patients undergoing major lower limb surgery Sanjay Agarwala, Abhijit S. Bhagwat, Jagdish Modhe* Departments of Orthopaedics and *Interventional Radiology, P. D. Hinduja National Hospital and Medical Research Centre, Veer
Savarkar Marg, Mahim, Mumbai 400016
Paper Received: April 2002, Paper Accepted: July 2002. Source of Support: Nil Code Number: is03027 ABSTRACT Thromboembolism remains a major preventable cause of postoperative mortality and morbidity in the Western world; very little attention has been given to this condition in the Indian patients. The present study was a prospective randomized study carried out in 104 Indian patients undergoing major orthopaedic lower limb surgery. The aim of the study was to determine the incidence of venographically proved deep vein thrombosis, the distribution of the thrombi and their significance. Group A consisting of patients treated prophylactically with LMWH showed a 43.2% incidence of deep vein thrombosis. Group B consisting of patients without any prophylaxis showed an incidence of 60% postoperatively. The incidence was high in patients undergoing total knee arthroplasty. Majority of the thrombi were distal, involving a short segment of the ipsilateral leg. Clinical signs and symptoms proved unreliable for diagnosing this condition. KEYWORDS: Deep vein thrombosis, low molecular weight heparin, thrombi How to cite this article: Agarwala S, Bhagwat AS, Modhe J. Deep vein thrombosis in Indian patients undergoing major lower limb surgery: Distribution of the thrombi and its significance. Indian J Surg 2003;65:159-62. INTRODUCTION Thromboembolism remains a serious preventable cause of postoperative morbidity and mortality in the western world. It is estimated that 20 million cases of lower extremity deep vein thrombosis occur in the USA alone.1 Routine postoperative venography has shown an incidence of 60% in patients undergoing orthopaedic surgery, with the highest rates seen in patients undergoing total knee arthroplasty.2 Undiagnosed and untreated deep vein thrombosis (DVT) of the lower extremities accounts for the vast majority of the 600,000 cases of pulmonary embolism in the USA each year.1 The true incidence of postoperative DVT and its pattern of distribution in Asian and Indian patients in not well highlighted. A review of literature revealed very few studies mainly from south east Asian countries, all of which have placed the incidence at 6% to 75%.2,3 No such study has been reported from India. It is generally agreed that proximal placed thrombi are potentially more dangerous in their ability to cause pulmonary embolism. The common pattern of distribution of the thrombi in the Caucasian groups is predominantly proximal. The distribution pattern of thrombi in Indian patients is unknown. The aim of the current study was to determine the incidence of DVT in patients undergoing major lower limb surgery, to detect the distribution pattern of the thrombi and to determine if prophylaxis with low molecular weight heparin (LMWH) had any effect on the incidence and distribution of the thrombi. MATERIAL AND METHODS This was a prospective randomized study which included 104 patients enrolled between February 1999 and Jan 2000. Patients undergoing total knee arthroplasty, total hip arthroplasty and fixation for fractures around the femoral neck that satisfied the inclusion criteria (Table 1) were included. All good clinical practice guidelines were observed and the hospital medical research subcommittee approved the study. Patients were included for only one surgical procedure and all cases were randomized to receive LMWH, dalteparin sodium (Fragmin, Pharmacia and Upjohn) or no prophylaxis. Patients randomized to receive LMWH received a dose of 2500IU two hours before surgery followed by a second dose at least six hours after the first dose. On the first and the subsequent postoperative days, a single dose of LMWH was given until contrast venography was performed on day 6+1. All patients were examined clinically on a regular basis for signs of DVT and a contrast venography was performed on suspicion, irrespective of the duration after surgery. No patient remained immobilized beyond 72 hours and a strict mobilization protocol was followed. The contrast venography performed by us was a modification of the conventional venography. By this technique we obtained subtracted images of the veins of both the legs simultaneously, using a lesser volume and concentration of the contrast material. All patients underwent contrast venography in supine position with simultaneous cannulation of the veins of the feet followed by an injection of a bolus chase run of 50cc, 180 mgs/ml Iohexol for each leg. Subtracted pictures of both the legs from the ankles to the abdomen were obtained, clearly showing the leg veins to the inferior vena cava (IVC). A thrombus was defined as a filling defect within the veins and data analysis was interpreted as above knee (proximal), below knee (distal), and as `long segment' or `short segment' deep vein thrombi. The results were interpreted as normal or deep vein thrombosis in one or more leg veins. Venographically diagnosed DVT was the primary endpoint for the determination of efficacy. The criterion for the diagnosis of DVT was a constant intraluminal filling defect seen in more than one projection. A venogram was considered suitable for evaluation if the major deep veins of the lower extremity, including two of the three pairs of calf veins, the popliteal vein, and the superficial femoral vein, could be visualized on two projections. In addition, non-opacification of a vein despite repeated injections of contrast medium was considered to indicate thrombosis. All other test results were classified as inadequate for interpretation. The venograms were classified as completely normal, suggestive of thrombosis or inadequate for interpretation. A positive venogram was always considered adequate. The thrombus was classified as distal if it involved the calf veins only and as proximal if it involved the popliteal or a more proximal vein. Patients who had both a proximal and a distal thrombus were classified as having proximal thrombosis. Thrombi involving muscular or superficial veins were recorded but were not considered deep vein thrombi. A two-tailed t-test for two independent samples was used to compare two means, and an uncorrected Chi-square test of significance was used for categorical data. The significance level was set at 0.05. RESULTS At the completion of the study, 104 patients were enrolled. There were 10 dropouts leaving 94 patients available for analysis. The demographic distribution and patient break-up is shown in Table 2. Group A comprised 44 patients and Group B 50. In group A, 43.2% (19/44) showed venographic evidence of DVT, with a maximum incidence of 55% in patients undergoing total knee arthroplasty. In Group B 60% (30/50) showed venographic evidence of DVT, with 72.7% occurring in patients undergoing total knee arthroplasty (Table 3). The incidence of DVT was statistically significant between the two groups. (P<0.05). Of the 19 cases of DVT in Group A, 19 (100%) were distal in location, 9 occurred in the ipsilateral leg (operated leg), 6 in the contralateral leg and 4 had bilateral involvement. There were 19 short segment and 3 long segment thrombi (Table 4). In Group B, 29 (96.66%) cases were of distal location, 19 of the 30 DVT were ipsilateral, 5 were contralateral and 6 were bilateral. There were 30 short segment and 6 long segment thrombi (Table 4). Individual distribution was as per Table 5. No patient had involvement of iliac veins. Of the 10 dropouts, 9 had inadequate venograms and one died from myocardial infarction in the postoperative period. Totally, 41.4% of the cases showed venographic evidence of thrombi but remained clinically asymptomatic. One patient experienced a complication from the venography. He developed transient swelling of the foot and pain from extravasation of the contrast into the tissue. DISCUSSION Our study has shown a 60% incidence of DVT in patients not receiving prophylaxis and a 43.2% incidence in patients receiving prophylaxis with LMWH. These figures are similar to those seen in the Western world.2,4 They are slightly lower than the incidence of 76.5% quoted by Dhillon et al in a study from an Asian country.3 The incidence was highest in patients undergoing total knee arthroplasty. The highlight of the study has been the striking difference in the distribution of the thrombi as compared to the Western studies. The predominant location of the thrombi in the Caucasians appears to be proximal, whereas in our study 100% of the thrombi in Group A and 96.66% in Group B were distal in location. These findings are similar to those of Wang et al who showed involvement of the distal veins in 95.6%.5 In the present study, a high percentage of cases (41.4%) with venographically demonstrated DVT remained asymptomatic as compared to 30% remaining asymptomatic in the study reported by Wang et al.5 Short segment thrombi accounted for 86.36% in Group A and 83.33% in Group B. Though there was no incidence of pulmonary embolism in this study, Haas et al have suggested a greater risk of symptomatic and asymptomatic pulmonary embolism from calf thrombi.6 In their patients with venographically proved calf thrombi, 6.9% had positive lung scans; in other studies the figure was much higher at 13%-15%.6,7 Kakkar and Doouss found that 6% to 13% of the calf thrombi propagate into the proximal veins increasing the risk of pulmonary embolism.8,9 Maynard showed a 42% incidence of proximal propagation.9,10 Our study found no significant statistical correlation between DVT and medical aliments such as diabetes mellitus, height, weight of the patients and the type of anaesthesia used. Clinical signs and symptoms were found to be unreliable in 41.4% of the cases that had venographically proven thrombi. In conclusion, the incidence of postoperative DVT in Indian patients undergoing major lower limb surgery is as high as seen in the Western world. Though prophylaxis with LMWH helps reduce the incidence, it does not provide complete protection and hence multiple modalities of prophylaxis are best employed. The most common distribution of DVT in Indian patients appears to be distal, similar to their Asian counterparts. This probably explains the lack of reliability of clinical signs in its early detection. Though these distal thrombi appear to be benign, they have a potential for proximal propagation and subsequent embolization. REFERENCES
Copyright 2003 - Indian Journal of Surgery. Also available online at http://www.indianjsurg.com The following images related to this document are available:Photo images[is03027t4.jpg] [is03027t3.jpg] [is03027t2.jpg] [is03027t1.jpg] |
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