Year : 2005 | Volume
: 39 | Issue : 1 | Page : 55--58
Pre and postoperative DVT in Indian patients - Efficacy of LMWH as a prophylaxis agent
S Agarwala, AS Bhagwat, Raju Wadhwani
Department of Orthopedics, PD Hinduja National Hospital & Medical Research Centre, Mumbai, India
PD Hinduja National Hospital & Medical Research Centre, Veer Savarkar Marg, Mahim, Mumbai - 400 016
Background: DVT incidence in Southeast Asian countries has been presumed to be low.
Method: The current article is based on a prospective study carried out on 130 patients of Indian origin. All patients were to undergo surgeries for fractures around the hip, THA or TKA. A pre operative CCDS was carried out to screen all the patients for pre existing DVT, followed by a postoperative CCDS at end of one week. All 100 enrolled patients received LMWH (Dalteparin Sodium) as a prophylaxis till CCDS.
Results: 31/90 (34.44%) showed signs of postoperative DVT with a predominantly distal presentation. 29/130 (22.3%) of the screened patients showed signs of pre-existing DVT. DVT incidence was highest in TKA patients.
Conclusion: Postoperative DVT is as common in the Indian population as any other parts of the world, significant number of patients have pre-existing DVT. LMWH helps reduce the rate and extent of postoperative DVT but does not give full protection. It is a safe and effective method for prophylaxis.
|How to cite this article:|
Agarwala S, Bhagwat A S, Wadhwani R. Pre and postoperative DVT in Indian patients - Efficacy of LMWH as a prophylaxis agent.Indian J Orthop 2005;39:55-58
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Agarwala S, Bhagwat A S, Wadhwani R. Pre and postoperative DVT in Indian patients - Efficacy of LMWH as a prophylaxis agent. Indian J Orthop [serial online] 2005 [cited 2013 May 19 ];39:55-58
Available from: http://www.ijoonline.com/text.asp?2005/39/1/55/36900
Incidence of postoperative deep vein thrombosis (DVT) within the western unprotected patient population ranges between 45 to 80%, about 1-2% of these develop fatal pulmonary thrombo embolism (PTE) ,2] . While this is a well recognized, extensively studied and published, the picture in the Indian subcontinent remains unknown. It has been always presumed that Indian and to an extent Asians have a very low incidence of deep vein thrombosis ,. DVT incidence in southeast asian countries has now been shown to be equal to that of their western counterparts ,, . Despite extensive search we found minimal published data from the Indian sub continent with exception of our own earlier study  . The present article is based upon a study conducted to reflect the true nature of the problem in Indian patients undergoing total knee arthroplasty, total hip arthroplasty & surgeries for fixation of fractures around the hip.
A study was undertaken to determine the extent of preexisting deep vein thrombosis prior to surgery and the incidence of postoperative deep vein thrombosis in Indians patients undergoing major orthopaedic surgeries on the lower limbs and to evaluate the thromboprophylactic efficacy and safety of low molecular weight heparin (LMWH) ( Dalteparin sodium; Pharmacia).
Materials and Methods
The study comprised of 130 patients selected in an open, prospective, nonrandomized method. All patients undergoing total knee, total hip arthroplasty and fixation surgery for fractures around the femoral neck from June 2000 to December 2001 were included. Patients were selected based on strict inclusion and exclusion criteria's [Table 1]. All good clinical practice guidelines were followed and the prior approval of the hospital medical research sub committee was obtained. Each patient was included for one operative procedure only and in all cases a prior well informed consent was obtained. For each case a complete protocol included demographic details, nature and duration of surgery, type of anesthesia and risk factor. Clinical signs of deep vein thrombosis (DVT) and colour contrast Doppler Sonography (CCDS) results were recorded. All patients were examined daily for a positive Homann's sign, prominence of superficial veins, leg and ankle swelling, skin discoloration and fever. All patients irrespective of the surgical procedure underwent a preoperative CCDS to look for DVT. Those patients with positive CCDS were excluded from the study, but the findings were recorded. This procedure of pre operative screening allowed the detection of preexisting preoperative DVT and exclusion of these patients left us with a more exacting population to study the post operative DVT. At any time patients were allowed to withdraw from the study.
Patients were discontinued from the study if they had excessive bleeding or complications related to the same or allergic reaction to Dalteparin detected to have or developed any of the exclusion criteria's during the study period.
Thromboprophylaxis with a low molecular weight heparin
On the day of surgery (Day 0), enrolled patients received 2500 international units (IU) of LMWH Dalteparin sodium two hours prior to surgery. A second similar dose was given subcutaneously on the evening of the day of the operation, at least six hours after the preoperative dose. On the first and subsequent postoperative days until CCDS was performed on day 7+1, 5000 international units of dalteparin were administered daily as a single subcutaneous (Sc) dose.
Post operatively, patients were observed closely for signs of DVT or pulmonary embolism. Patients were monitored for changes in haematocrit and hemoglobin levels, blood sugar levels, renal profile, and change in liver function parameters on postoperative days 1, 4 and on the day of the CCDS (Day 7 +/- 1 or earlier if needed).
Bleeding was assessed on the basis of intraoperative blood loss by mop weight and suction bottle volume, transfusion requirements, a decrease in haematocrit, and clinically identified bleeding complications. Throughout the study period drugs and other modalities for prevention of deep vein thrombosis (DVT) such as Aspirin, pressure stockings and drugs known to interact with thrombosis were avoided. Bilateral CCDS was performed on all patients on Day 7+ 1. When clinical DVT or pulmonary embolism was suspected, the CCDS was done earlier.
CCDS and Efficacy end points
All CCDS examinations were performed using a logic 500GE colour Doppler machine with 7.5 MHz linear phased array transducers or 3.5MHz convex transducers. Colour sensitivity was maximized. The examination consisted of venous compression, colourflowimaginingandaugmentation methods. Bilateral examination was performed in all patients. All major veins of the lower limbs including the illiac veins were examined. The active calf examination in the sitting position was not always possible in post operative patients and examination was done in supine position in these patients. In view of the calf veins not being examined in the sitting position we used the augmentation technique in the supine position, whereby giving distal augmentation in the calf, the proximal position of calf veins were evaluated for presence of colour flow. A positive CCDS was defined by the detection of non-compressible intraluminal thrombus, diminished augmentation and lack of or poor flow. Lack of spontaneous flow was noted especially when the vein was not well visualized (Distal femoral vein in adductor canal).
The primary end point was a CCDS demonstrable DVT. The results were classified as completely normal, suggestive of thrombus or inadequate for interpretation. The thrombi were classified as distal if they involved the calf veins only, proximal if it involved the popliteal or a more proximal vein. Patients who had both proximal and distal thrombus were considered as having proximal thrombus.
Assessment of safety
Objective measures of bleeding included intraoperative blood loss as estimated by the anesthesiologist, postoperative blood loss as measured from drains, blood transfusion requirements, and changes in hemoglobin and haematocrit. Decisions regarding transfusion were based on standard clinical practice and were made by the attending surgeon. Clinically identified bleeding complications were considered major if they were fatal, if they required a transfusion, reoperation, or prolonged hospitals stay. Woundrelated complications and minor bleeding were also recorded.
A two-tailed t-test for two independent samples was used to compare two means, and an uncorrected chi-squared test of significance was used for categorical data. The significance level was set at 0.05.
A hundred thirty patients were screened with pre operative CCDS of which 100 patients were finally enrolled into the study. Twenty-nine were excluded on the basis of positive pre operative CCDS for pre existing DVT, a single patient was excluded due to inadequate visualization. There were 26 males and 74 females within the enrolled group with average age of 58 years (range 28-88 years). There were 61 total knee arthroplasty, 27 total hip arthroplasty and 12 fixations for fractures around the femoral neck. All except one patient underwent the procedure under general anaesthesia. There were 10 dropouts (3 on patient's request, 7 due to high postoperative serum creatinine >1.7mg/dl) leaving 90 patients finally to complete the study. All 90 patients underwent CCDS on post-operative 7day + 1 day. In the study group concomitant illnesses like hypertension (16), diabetes (14), rheumatoid arthritis (13) and few like RHD, CABG, bronchial asthma etc were noted.
Incidence of DVT
Of the 90 patients 31 (34.44%) showed signs of post operative DVT while 59 (65.55%) had no DVT findings on CCDS. There were 29 distal and two proximally located thrombi. The predominant limb involved was the ipsilateral operated limb in 25 and bilateral and contralateral limb involvement in 3 cases each [Table 2]. Proximal thrombi involved the popliteal and the femoral veins; there were no illiac vein involvement. Within the groups, patients undergoing TKA had the highest rate of post operative DVT at 40.90% followed by the THA group at 22.22%. No DVT was seen in the fracture fixation group. Only 11 (35.48%) of the 31 patients with post operative DVT showed any clinical signs of DVT, while CCDS was confirmatory in only 9 cases. The preoperative CCDS showed predominant distal thrombi location in 24 cases (82.75%) with equal distribution with respect to the side of limb involved.
Thirty-five patients required post operative blood transfusions. On an average 1.4 transfusions were required. Mean haemoglobin levels were 11.85 gm% at basal in all cases. After the surgery, at day 1 mean Hb level had significant reduction i.e. reduction of 19.5% from basal. At day 7th, mean Hb level were 9.31 gm%. Mean haemoglobin levels had same trend among the DVT and no DVT cases and if you compare the difference was not statisticaly significant.
All except one patient was examined clinically between the 5th and the 7th week for signs of DVT, 11 patients showed some positive clinical signs.
Contrary to well-established belief of post operative DVT not occurring in Indian patients this study has helped establish otherwise. Not only has it established that postoperative DVT is as common in our patients as in the Caucasian's, but it also highlights the fact of pre-existing DVT. Twenty-nine of the 130 patients screened showed preexisting DVT. A total of 34.44% of patients developed DVT despite prophylaxis with LMWH. This highlights the need for active and at times aggressive prophylaxis.
The incidence of DVT in patients undergoing total knee arthroplasty was higher than in patients undergoing total hip arthroplasty which is similar to published literature ,, . There was no DVT in patients operated with fixations for fractures of the femoral neck, but this may be due to the very small number of patients as compared to the other two groups.
Large majority of the thrombi were distally located, but about 23% of these can propagate proximally increasing the chances of pulmonary thrombo-embolism (PTE) , . The predominant distal location of the thrombi reflects a contrary pattern of deep vein thrombosis in the Asian/ Indian populations , . This study has shown that LMWH reduce the incidence and the extent of DVT, a finding earlier put forward by Dahl and Scharwz , . Involvement of the ipsilateral limb is as per expectation and published literature, but the contralateral limb involvement points towards the need to extend the prophylactic measures to that limb also. Patients with pre-existing DVT probably need additional prophylactic attention to prevent propagation and PTE.
The fact that a significant number of patients developed DVT despite prophylaxis points to the fact that no single method gives complete protection and hence other modalities may help further reduce the incidence  . The duration of antithrombotic therapy remains controversial but one thing remains clear that postoperative DVT can occur as late as 57 weeks. Though the patients in this study were followed up clinically upto 7 weeks into the postoperative period no repeat CCDS was built into this study protocol. What significance delayed DVT has in the Indian patients' remains to be seen  . We found LMWH (Dalteparin sodium) a safe and easy to administer thromboprophylactic agent, but agree that the problems related to excessive bleeding and the cost of the prophylaxis are probably a major hurdle to its wide acceptance. The use of pressure stockings and early mobilization may be worthwhile in cases where LMWH cannot be used ,. Since all but one patient underwent surgery with general anesthesia no relation could be drawn between the type of anesthesia and DVT  .
Probable explanation for low prevalence of DVT in Indian population could be that the total number of arthroplasty surgeries carried out is less than those in the western developed countries. Secondly importance is given to clinical signs which can serve only as a guiding measure towards investigating for DVT but have proven unreliable , .
Acknowledgment: The study was supported by a grant from Pharmacia & Upjohn India Pvt. Ltd.,,
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