Venous thromboembolic disease prophylaxis among general surgeons in Malaysia

OBJECTIVE: The aim of this study was to analyse the current practice of venous thromboembolism (VTE) prophylaxis among general surgeons in Malaysia. METHODS: A questionnaire survey was conducted among general surgeons attending the annual Malaysian College of Surgeons meeting in 2002. A total of 110 questionnaires were distributed to specialist-grade general surgeons with varying subspecialty interests. RESULTS: Seventy-seven (70%) surgeons returned the questionnaire. Of these, 43% were of the opinion that VTE was as common in Asian patients as in the West. Selective VTE prophylaxis was used by 99% in their practice. The indications for use, in order of frequency, were: previous VTE disease, risk grading, prolonged surgery, obesity, malignancy and age. Low molecular weight heparin was the most common type of prophylaxis used. VTE-related morbidity was reported by 44 surgeons (57%) over the past year, and 39% of these cases were fatal. CONCLUSION: The high incidence of VTE-related complications indicates that the use of thromboprophylaxis is either insufficient or not matched to the level of risk. Updated guidelines on VTE prophylaxis should be used so that a standardized approach can ensure that patients receive adequate prophylaxis where indicated.     

Anaesthesia and the prophylaxis of thromboembolic diseases

Within the last 10 years or so, studies in groups of patients known to be at high risk of postoperative thromboembolism have revealed that choice of anaesthetic technique can influence the incidence of these complications. When measured by an accurate, objective method such as venography, the incidence of deep venous thrombosis (DVT) is of the order of 50% after hip or knee replacement and as high as 75% after repair of hip fracture.The use of lumbar epidural or subarachnoid spinal anaesthesia is associated with a significant reduction in the number of patients who develop DVT after these types of surgery. There is also evidence that the incidence of pulmonary embolus is reduced.However, long term outcome does not appear to be altered by the use of regional techniques. Since pulmonary embolus appears now to be a minor cause of death after hip replacement, a significant reduction in mortality would seem unlikely if epidural, rather than general, anaesthesia were used, although no such information is available at present.Current recommendations for the widespread use of low dose heparin prophylaxis, and the lack of consensus as to the safety of spinal and epidural block in these circumstances, add to the dilemma of whether the theoretical benefits of such techniques in the prophylaxis of thromboembolic diseases translate into actual benefits for patients.The exact status and role of the new low molecular weight heparins has yet to be decided. Thus, despite the fascinating evidence of the effects and mechanisms of anaesthetic technique on the incidence of thromboembolic disease, it seems as if the information may prove of only theoretical value, at least until much further consideration and work has been done, to address the issues of safety, and of effect on outcome. The author makes no apology therefore, for quoting again the epithet of the late Professor Mitchell on the general topic of thromboembolic prophylaxis: ‘What we have is not what we want; what we want is not what we need; what we need is not what we can obtain.’²⁸     

Meta-analysis of thromboembolic prophylaxis after total knee arthroplasty

We performed a meta-analysis of the English literature to assess the efficacy of four common regimes for thromboembolic prophylaxis after total knee arthroplasty: aspirin, warfarin, low-molecular-weight heparin (LMWH) and pneumatic compression. We reviewed 136 articles and abstracts published between January 1980 and December 1997. Papers not using routine venography and a lung scan or angiography to detect deep-venous thrombosis (DVT) and pulmonary emboli (PE) respectively, were excluded. Of the 136 studies, 23 with 6,001 patients were selected. The incidence of DVT was 53% (1,701/3,214) in the aspirin group, 45% (541/1,203) in the warfarin group, 29% (311/1,075) in the LMWH group, and 17% (86/509) in the pneumatic compression device group. Intermittent pneumatic compression devices and LMWH were significantly better than warfarin (p < 0.0001) or aspirin (p < 0.0001) in preventing DVT. The incidence of asymptomatic PE was 11.7% in the aspirin group (222/1,901), 8.2% (101/1,229) in the warfarin group and 6.3% (24/378) in the pneumatic compression group. No studies with LMWH used routine lung scans. Warfarin and pneumatic compression were significantly better than aspirin in preventing asymptomatic PE (p < 0.05). The incidence of symptomatic PE was 1.3% (23/1,800) in the aspirin group, 0.4% (2/559) in the warfarin group, 0.5% (2/416) in the LMWH group and 0% (0/177) in the pneumatic compression group. No statistically significant difference was noted between the above prophylactic regimes due to the very small incidence of symptomatic PE. Prophylaxis for thromboembolic disease in TKA may have to include a combination of some of the above regimes to incorporate their advantages.     

Nonpharmacologic thromboembolic prophylaxis in total knee arthroplasty.

Deep venous thrombosis is the most common complication in patients having elective total knee replacement. Pneumatic compression devices play an important role in the prophylaxis of deep venous thrombosis and effectively decrease the risk of distal deep venous thrombosis. The combination therapy with pharmacologic agents has the benefit of decreasing the rate of proximal deep venous thrombosis and therefore is recommended. In the absence of clinical data, recent in vivo flow studies suggest that calf or combined foot and calf compression are superior to foot compression alone. Epidural anesthesia in comparison with general anesthesia decreases the incidence of thromboembolic disease after total knee arthroplasty. Although hypotensive anesthesia and intraoperative heparin have been proven to substantially lower the incidence of deep venous thrombosis after total hip arthroplasty, the current literature does not support its application during the implantation of a total knee replacement. Pneumatic compression devices are an important part of deep venous thrombosis prophylaxis especially in the early postoperative period considering that pharmacologic anticoagulation is contraindicated in the first 12 hours after spinal anesthesia and in the presence of an epidural line.     

A meta-analysis of thromboembolic prophylaxis in total knee arthroplasty

Deep venous thrombosis (DVT) is common in total knee arthroplasty (TKA). Because of the rarity of the most serious outcomes, most randomized controlled trials lack the power to analyze these outcomes. A meta-analysis was performed for agents used in DVT prophylaxis in TKA employing a Medline literature search. Study inclusion criteria were randomized controlled trials comparing prophylactic agents in elective TKA with mandatory screening for DVT by venography. Fourteen studies (3,482 patients) met inclusion criteria. For total DVT, all agents except dextran and aspirin protected significantly better than placebo (P < .0001). For proximal DVT rates, low-molecular-weight heparin was significantly better than warfarin (P = .0002). There was a trend that aspirin was better than warfarin (P = .0106). No significant difference was found for symptomatic pulmonary embolism, fatal pulmonary embolism, major hemorrhage, or total mortality.     

A meta-analysis of thromboembolic prophylaxis following elective total hip arthroplasty

BACKGROUND: Although several agents have been shown to reduce the risk of thromboembolic disease, there is no clear preference for thromboembolic prophylaxis in elective total hip arthroplasty. The purpose of this study was to define the efficacy and safety of the agents that are currently used for prophylaxis against deep venous thrombosis -- namely, low-molecular-weight heparin, warfarin, aspirin, low-dose heparin, and pneumatic compression. METHODS: A Medline search identified all randomized, controlled trials, published from January 1966 to May 1998, that compared the use of one of the prophylactic agents with the use of any other agent or a placebo in patients undergoing elective total hip arthroplasty. For a study to be included in our analysis, bilateral venography had to have been performed to confirm the presence or absence of deep venous thrombosis. Fifty-two studies, in which 10,929 patients had been enrolled, met the inclusion criteria and were included in the analysis. The rates of distal, proximal, and total (distal and proximal) deep venous thrombosis; symptomatic and fatal pulmonary embolism; minor and major wound-bleeding complications; major non-wound bleeding complications; and total mortality were determined for each agent in each study. The absolute risk of each outcome was determined by dividing the number of events by the number of patients at risk. A general linear model with random effects was used to calculate the 95 percent confidence interval of risk. A crosstabs of study by outcome was performed to test homogeneity (ability to combine studies). The risk of each outcome was compared among agents and between each agent and the placebo. RESULTS: With prophylaxis, the risk of total (proximal and distal) deep venous thrombosis ranged from 17.7 percent (low-molecular-weight heparin) to 31.1 percent (low-dose heparin); the risk with prophylaxis with any agent was significantly lower than the risk with the placebo (48.5 percent) (p < 0.0001). The risk of proximal deep venous thrombosis was lowest with warfarin (6.3 percent) and low-molecular-weight heparin (7.7 percent), and again the risk with any prophylactic agent was significantly lower than the risk with the placebo (25.8 percent) (p < 0.0001). Compared with the risk with the placebo (1.51 percent), only warfarin (0.16 percent), pneumatic compression (0.26 percent), and low-molecular-weight heparin (0.36 percent) were associated with a significantly lower risk of symptomatic pulmonary embolism. There were no significant differences among agents with regard to the risk of fatal pulmonary embolism or of mortality with any cause. The risk of minor wound-bleeding was significantly higher with low-molecular-weight heparin (8.9 percent) and low-dose heparin (7.6 percent) than it was with the placebo (2.2 percent) (p < 0.05). Compared with the risk with the placebo (0.28 percent), only low-dose heparin was associated with a significantly higher risk of major wound-bleeding (2.56 percent) and total major bleeding (3.46 percent) (p < 0.0001). CONCLUSIONS: The best prophylactic agent in terms of both efficacy and safety was warfarin, followed by pneumatic compression, and the least effective and safe was low-dose heparin. Warfarin provided the lowest risk of both proximal deep venous thrombosis and symptomatic pulmonary embolism. However, there were no identifiable significant differences in the rates of fatal pulmonary embolism or death among the agents. Significant risks of minor and major bleeding complications were observed with greater frequency with certain prophylactic agents, particularly low-molecular-weight heparin (minor bleeding) and low-dose heparin (both major and minor bleeding).     

Audit of thromboembolic prophylaxis in hip and knee surgery.

An audit of the departmental policy for thromboembolic prophylaxis was undertaken, examining the use of TED stockings, administration of subcutaneous low-dose heparin and inclusion into a multicentre pulmonary embolism prevention (PEP) trial for fractured neck of the femur. The results showed that despite an established unit policy, only 43% of patients undergoing primary hip replacement and 14% undergoing revision replacement received subcutaneous heparin. All patients undergoing primary and revision total knee replacement received subcutaneous heparin, but 75% of these patients received an incorrect dose. Use of TED stockings in patients who had sustained a fractured neck of the femur, ranged from 0% to 70% depending on the type of fixation. Use of subcutaneous heparin in these patients ranged between 0% and 20% and inclusion into the PEP trial from 0% to 20%. The results of this study were presented to the clinicians working in the orthopaedic department and 3 months later the audit cycle was completed by repeating the study. It was found there was a statistically significant improvement in the administration of subcutaneous heparin and in the wearing of TED stockings in the joint arthroplasty group as well as in the inclusion of hip fracture patients into the PEP trial. This study demonstrates that established protocols are of little value unless audited and that completion of the audit cycle is essential. It does not attempt to show that one prophylactic method is better than another.     

Postoperative thromboembolic complications despite heparin prophylaxis in major abdominal surgery

181 patients who received low-dose heparin prophylaxis in connection with major abdominal surgery were screened for postoperative thromboembolism by means of the 125 I-fibrinogen uptake test, venography and ventilation/perfusion lung scans. Among a number of potential risk factors analyzed only colonic surgery and preoperative anaemia were associated with significantly increased risk of postoperative thromboembolism.     

Pathogenesis and prophylaxis of venous thromboembolic complications at large ventral hernias

Overall 188 patients undergone surgical treatment due to large postoperative ventral hernias are analyzed. It is demonstrated that venous hemodynamics at these patients before surgery is characterized by disorders of "abdominal-caval pump" function due to anterior abdominal wall destruction and low mobility of diaphragm's cupula. The recovery of their functions is the key point in prophylaxis of thromboembolic complications.     

Intraoperative adjusted-dose heparin thromboembolic prophylaxis in primary total hip arthroplasty.

Intraoperative, fixed, intermittent, low-dose intravenous heparin prophylaxis has been reported to significantly reduce the incidence of thromboembolic disease from 24.3% to 8.3% after primary total hip arthroplasty (THA). This study examined the potential efficacy of adjusted-dose intraoperative heparin administration, keeping the activated clotting time at 30%-50% greater than normal. It was hypothesized that prolongation of clotting parameters in a uniform manner would further decrease the incidence of thromboembolic disease postoperatively. Sixty-one patients completed the protocol. The overall incidence of thromboembolic disease was 9.8%. Five patients had a positive postoperative venogram: four in the calf and one in the proximal deep thigh vein. One patient had a symptomatic nonfatal pulmonary embolus diagnosed by ventilation-perfusion scan. There were no complications related to heparin administration. This approach was therefore equally as effective as the fixed-dose regimen, and it further confirmed the efficacy and safety of an intraoperative heparin prophylaxis regimen. The extra efforts required to maintain a constant intraoperative level of anticoagulation did not prove advantageous over the simpler, fixed-dose regimen in reducing the incidence of thromboembolic disease after primary THA.     

Venous thromboembolic complications in abdominal and vascular surgery. The risk factors and measures of prophylaxis

There were analyzed 4675 histories of cases of patients, who were operated on for disease of the digestion organs (3349) and for obliterating atherosclerosis of abdominal aorta and peripheral arteries (1326). The risk factors of occurrence were established, the prophylaxis methods for venous thromboembolic complications (TEC) in postoperative period were elaborated. High efficacy of application of fraxiparine in the venous TEC prophylaxis in abdominal and vascular surgery was noted.     

Antibiotic prophylaxis in clean general surgery

Objective: To find out the incidence of surgical site infection in clean general surgery cases operated without prophylactic antibiotics. Design: A comparative study. Place and Duration of Study: The study was carried out in Combined Military Hospital, Pano Aqil Cantonment, from July 2003 to December 2004. Patients and Methods: One hundred and twenty-four clean surgical cases operated without antibiotic prophylaxis between July 2003 and December 2004, were studied and these were compared with similar number of cases who received antibiotics. The data was collected and analyzed using software SPSS (version 10.0). Chi-square and student "t" test were used to analyze the association between antibiotics and wound infection. Results: The most frequent operation was repair of various hernias, 69.3% in group A and 75% in group B. More operations were carried out between 21-30 years, 38.7% in group A and 41.9% in group B. Surgical site infection occurred in one patient (0.8 %) in each group. Chi- square test (0.636) applied to group A and B showed no association of infection and administration/ no administration of antibiotics (p > 0.25). The "t" test applied on group A and B (t=0) also showed no significant difference between administration of antibiotics/ no antibiotics and infection (p > 0.25). Conclusion: The use of prophylactic antibiotic in clean, non implant and elective cases is unnecessary.     

Antimicrobial prophylaxis in general surgery.

When used appropriately, antimicrobial prophylaxis is highly beneficial and cost effective. Antibiotics are not indicated for "clean procedures" such as hernia and breast surgery. A single preoperative dose will suffice, followed by an intraoperative dose if the operation takes more than 3 hours. For vascular (prosthesis or groin wound), head and neck (pharynx entered), thoracic (gastrointestinal or respiratory entrance) and high-risk gastroduodenal and biliary procedures, cefazolin, 1 g intravenously, is indicated. For procedures involving small intestine, appendix or penetrating abdominal trauma, cefoxitin or cefotetan, 2 g intravenously, is indicated. For colorectal procedures, either oral neomycin plus erythromycin or intravenous aminoglycoside plus clindamycin (or metronidazole) are effective. If valvular heart disease is present, endocarditis prophylaxis should be administered.     

Aspirin prophylaxis of venous thromboembolic disease following fracture of the upper femur.

In a prospective study of 51 patients with fractures of the femoral neck, aspirin was used as a prophylactic measure against thromboembolic disease. Thrombi were detected by cuff impedence plethysmography, Doppler ultrasonography and ascending venography. Thrombi were identified in 20 (39.2%) of the patients. There was no significant difference between the frequency with which thrombi occurred in men and in women. Blood salicylate values were the same for patients who had and who did not have thrombi. There were no instances of pulmonary embolism. The frequency of deep vein thrombosis was comparable to that in a previous series of untreated patients from the same centre. It appears from this study that in these cases prophylaxis against venous thromboembolism using aspirin in a dosage of 600 mg bid is ineffective.     

Application of clexane for prophylaxis of thromboembolic complications in surgery of morbid obesity

The results of comparative clinical application of low-molecular heparin Clexan vs heparin for the thromboembolic complications prophylaxis in surgical treatment of morbid obesity were summarized.