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ORIGINAL ARTICLE |
Department of Surgery, Kurume University School of Medicine Kurume, Japan
Shinichi Hiromatsu, MD Tel: +81 942 35 8967 Fax: +81 942 35 8967 Email: kaeru{at}med.kurume-u.ac.jp, Department of Surgery, Kurume University School of Medicine, 67 Asahi-machi, Kurume-shi, Fukuoka-ken, 830-0011 Japan.
ABSTRACT
Venous thromboembolism is the most preventable illness among patients in hospital. We prepared guidelines for the prophylaxis of venous thromboembolism, based on previous experience of perioperative risk factors. The aim of this study was to evaluate the effectiveness of these guidelines. All 1,467 patients who underwent surgery for thoracic or cardiovascular disease between April 2002 and July 2004, before the prophylactic guidelines were implemented, were assigned to group A. Another 1,389 patients who had surgery between August 2004 and December 2006, after the guidelines had been implemented, formed group B. The incidences of venous thromboembolism perioperatively in the 2 groups were compared. Six (0.4%) patients in group A developed deep vein thrombosis or pulmonary embolism, whereas no patient in group B experienced thromboembolism. The difference between groups was significant, so we consider our guidelines for venous thromboembolism prevention in the perioperative period to be clinically useful.
Key Words: Intermittent Pneumatic Compression Devices • Pulmonary Embolism • Stockings • Compression • Venous Thromboembolism • Venous Thrombosis
INTRODUCTION
Venous thromboembolism (VTE), which includes deep venous thrombosis (DVT) and pulmonary embolism (PE), is an important complication after general surgery, particularly in patients having major surgery, serious trauma, certain medical conditions, or prolonged immobility from any illness. Previous reports have demonstrated that DVT occurs in >20% of patients who have major surgery, and in >40% of those undergoing major orthopedic surgery.1 PE is associated with 1%–10% of hospital deaths in Western countries.2–7 Until recently, VTE was considered rare in Japan, but its incidence has been increasing, presumably because the Japanese diet is becoming Westernized, specifically, the fat content is rising. VTE prophylaxis is required in specific patients, and several guidelines have been developed, including those of the American College of Chest Physicians. In Japan, the first guidelines for the prevention of VTE were published in February 2004; however, they were not easy to use because detailed methods for preventing VTE in the perioperative period were not given. We concluded that it was necessary to establish guidelines that suited our department. Thus we drew up new guidelines to reduce the risk of VTE perioperatively. The aim of this study was to evaluate the effectiveness of our prophylactic guidelines for VTE.
PATIENTS AND METHODS
Between April 2002 and December 2006, 2,856 patients underwent surgical treatment under general or spinal anesthesia for thoracic or cardiovascular disease in our department. The 1,467 patients who underwent the surgery between April 2002 and July 2004, before our departmental prophylactic guidelines had been implemented, were assigned to group A; the other 1,389 patients who underwent surgery between August 2004 and December 2006, after our guidelines were implemented, formed group B. Our guidelines were prepared on the basis of findings in group A. The patients who developed VTE in group A had some risk factors perioperatively (Table 1
). The risk factors for perioperative PE were cancer, varicose veins, body mass index (BMI) 
25 kg·mm–2, a central venous catheter, and long periods of being bed-ridden. We added thrombophilia, previous history of PE, congestive heart failure, and chronic respiratory dysfunction to this list. The risk factors for perioperative VTE were previous VTE, thrombophilia, long-term confinement to bed, long-term central venous catheterization, varicose veins, BMI 25 kg·mm–2, congestive heart failure or chronic respiratory dysfunction, lung cancer, and benign lung disease (undergoing surgery without heparin). Surgery without heparin was included among the risk factors because heparin is used in many operations in our department, except those for lung disease and varicose veins. Contrast computed tomography (from the episternum to the tibial tuberosity) was performed preoperatively in all patients who had prior history of VTE. After hospitalization, lower limb venous ultrasonography (IPC-1530; Aloka, Japan) was performed in patients who had these risk factors.
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. Patients at low risk had early mobilization and graduated compression stockings during hospitalization. It is unnecessary to use intermittent pneumatic compression (IPC) during operations in low-risk patients because we always use heparin in cardiovascular surgery (except for varicose veins). If patients cannot walk early on, they perform self-activated foot joint movements on the bed. In those at moderate risk, IPC is added during the operation. IPC is also used regardless of risk category when the foot cannot be moved actively (e.g., unconscious patient). Postoperative anticoagulant therapy is added to the prophylaxis for high-risk patients. The prophylaxis for grade 4 patients does not include IPC during hospitalization because of the presence of thrombus. The fundamental prophylaxis for grade 4 patients is IVC filter placement and anticoagulation therapy; however, during surgery, anticoagulation therapy is suspended. In addition, we brief all patients on VTE and explain that the risk increases because they move less while in hospital compared to normal daily life, and the foot joint can be moved even when resting on a bed and should be moved for 10 minutes every hour.
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RESULTS
There were no significant differences between the 2 groups in terms of demographics and clinical characteristics, with the exception of duration of hospital stay (Table 3). Of the 6 patients who developed VTE in group A, 2 experienced it a few days after first ambulation. Patient no. 6, who underwent surgery for varicose veins, suffered PE when leaving the hospital after discharge. She was found at the entrance in cardiopulmonary arrest, so we immediately transported her to our ward and performed appropriate intervention, including percutaneous cardiopulmonary support. Although we were able to save her life, she suffered serious brain damage and is currently bedridden. In this series, no patient with lower limb swelling developed DVT. The patients who developed PE did not have peripheral phlebothrombosis on computed tomography, and we believed the PE all came from veins in which the thrombi first originated. Anticoagulant therapy was applied in all 6 patients, and 5 of them had thrombolysis. One underwent thrombectomy of the pulmonary artery, and 2 had inferior vena caval (IVC) filter placement; the rest improved on anticoagulant therapy (Table 4).
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). Prophylactic management appropriate for the risk category was carried out perioperatively. No patient in group B developed VTE after the prophylactic guidelines were applied. The difference between the 2 groups in terms of prevention of VTE was statistically significant. Because PE is a complication that must be avoided at all costs, we are currently continuing to use the present guidelines.
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Hill and colleagues1 reported that DVT occurred in over 20% of patients who underwent major surgery and the postoperative risk of PE can be as high as 5% in the highest risk groups. However, many patients probably do not receive adequate prophylactic management.8–9 The American College of Chest Physicians, the Surgical Care Improvement Project, the International Union of Angiology, and the National Comprehensive Cancer Network have issued specific guidelines for prophylaxis.10–12 The risk evaluation and prevention aspects of each set of guidelines, including ours, are the same.
Previous reports have generally recommend graduated compression stockings and IPC for low-risk patients, and anticoagulant administration for high-risk patients. Approximately 25% of all VTE cases are associated with hospitalization, and 50%–75% of VTE in hospitalized patients occur perioperatively.13 The risk of VTE rises because hospitalized patients are less mobile that in normal daily life. DVT is asymptomatic in most cases, probably because patients walk less than normally. Hospitalization may be one of the greatest risk factors for VTE. Riber and colleagues14 reported that the incidence of VTE after day surgery was a modest 0.04%. Patients who undergo outpatient surgery under local anesthesia are relatively low-risk because they can walk soon after the operation. However, there have been few reports of PTE after cardiopulmonary bypass. In our department, although many operations are prolonged, we believe there is a lower risk of PE because most are performed using heparin. In group A, 4 of 6 patients who developed PE underwent surgery for lung disease without heparin; PE after coronary artery bypass grafting (CABG) is uncommon. Compared with patients undergoing general surgery, those in our department have a higher risk of PE in the postoperative period because they may be immobilized for longer, for example, if prolonged ventilation is required. The incidence of DVT and PE after CABG depends on postoperative thromboprophylaxis, the presence of an indwelling central venous catheter, and early ambulation. Heparin-induced thrombocytopenia, which is generally associated with a high incidence of DVT and PE, occurs in approximately 3.8% of cardiac surgery patients on high-dose intravenous unfractionated heparin postoperatively. Sequential compression devices have not been effective in reducing the incidence of DVT in ambulating CABG patients when added to routine use of compression stockings. Very large clinical trials are necessary to prove the effectiveness of early ambulation, mechanical and pharmacologic interventions (compression stockings, aspirin) in reducing the incidence of PE after cardiac surgery.
IVC filters are not mentioned in detail in the Japanese guidelines for prevention of VTE. In the guidelines we developed, an IVC filter should be inserted in grade 4 patients. We inserted an IVC filter in 2 patients in group B: one had suffered femoral vein thrombus after replacement of the ascending aorta due to acute dissection, and was scheduled for abdominal aortic aneurysm repair the following week; the other had lung cancer and history of DVT, with a thrombus detected in the popliteal vein by preoperative ultrasonography, which was captured by the IVC filter. However, further experience is necessary before recommending IVC filter insertion perioperatively because of the small number of cases in this series.
Although most postoperative PE occurs when a patient walks for the first time after an operation, in our series, 2 of 6 patients developed PE a few days after first ambulation. VTE prophylaxis should not be stopped until the patient can walk normally because most are only slightly ambulant in the early postoperative period. A systematic review and 2 meta-analyses have shown that graduated compression stockings reduce the risk of DVT after general surgery.15,16 Compression stockings are the easiest form of prophylaxis, so patients should be strongly encouraged to wear them and exercise their lower limbs as much as possible until they can resume normal daily activities. VTE is a serious complication, but our new prophylactic guidelines have been useful in reducing the incidence in our department.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:505-509
© 2009 by SAGE Publications
DOI: 10.1177/0218492309348639
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