Ronald S. Adler, MD, PhD (Radiology)
Anne R. Bass, MD (Medicine)
Theodore R. Fields, MD (Medicine)
Steven B. Haas, MD (Orthopedics)
Michelle Horvath, RN (Patient Care and Quality Management)
Richard L. Kahn, MD (Anesthesia)
Jacqueline Kostic, RN (Nursing)
Steven K. Magid, MD (Medicine)
Stephen A. Paget, MD (Medicine)
Eduardo A. Salvati, MD (Orthopedics)
Andrew Sama, MD (Orthopedics)
Nigel E. Sharrock, MD (Anesthesia)
Geoffrey H. Westrich, MD (Orthopedics)
The establishment of the Committee on DVT/PE Prophylaxis was triggered by an increase in the incidence of in-hospital postoperative pulmonary emboli (PE) from approximately 0.3% to 0.97% of inpatient surgeries in the third quarter of 2002 at the Hospital for Special Surgery (HSS). The increase in incidence occurred equally among knee, hip, and spine patients.
Creation of this committee was also motivated by a lack of consensus among the HSS medical and surgical attending staff as to the best approach to prophylaxis of venous thromboembolism (VTE) following orthopedic surgery. The committee was therefore asked to make evidence-based recommendations regarding VTE prophylaxis for patients hospitalized at HSS who are at high risk for VTE.
Support for the committee’s mandate has not been unanimous (although there is universal agreement that every person undergoing major orthopedic surgery should receive some form of prophylaxis). Some physicians have expressed concern that firm guidelines might be misused in a medico-legal setting. Others have argued that rates of VTE are so low at HSS that changes in the system are not necessary. The committee did find that rates of postoperative VTE at HSS are low, and comparable to those in the published literature from other institutions. Nonetheless, the recent increase in PE incidence necessitated an examination of the problem. In addition, surgeons at HSS who perform a small volume of joint arthroplasties, or manage a small number of fracture patients, for example, will benefit from the establishment of guidelines for VTE prophylaxis. There are also a number of "special instances" such as bilateral or staged arthroplasties, or complex spine cases, where the risk of VTE may be high and guidelines will be beneficial. Guidelines can also be helpful medico-legally. For example, these guidelines, supported by the published experience at HSS, allow for the use of aspirin alone as VTE prophylaxis in certain instances where the outside medical literature recommends warfarin or low molecular weight heparin (LMWH).
These guidelines are meant to provide a consistent, and evidence-based approach to the management of VTE prophylaxis at HSS. Guidelines are not meant to supersede clinical judgment, however, and may at times require tailoring to an individual patient. Thus, for example, an elderly patient undergoing joint arthroplasty who is felt to be at unacceptably high risk for bleeding on warfarin or LMWH, might be have to be treated with aspirin (assuming it is not contraindicated).
(Note: The dosages below may need to be modified for pediatric patients.)
IPC should be applied promptly in the recovery room following surgery and should be used continuously at all times when patients are in bed. All members of the HSS staff should know how to put on compression stockings and all members of the staff (including physicians, physical therapists and nursing staff) are responsible for replacing IPC stockings when patients return to bed.
The use of hypotensive epidural anesthesia is widespread at HSS and lowers the risk of postoperative VTE. The use of LMWH in conjunction with epidural anesthesia has been associated with the development of epidural hematomas, a potentially catastrophic complication. The following guidelines apply to the use of LMWH in patients who are to undergo, or have undergone epidural anesthesia, and to those who have an epidural catheter in place for the administration of continuous anesthesia postoperatively:
The rate of pulmonary embolism (PE) occurring in hospital following hip arthroplasty (THR) at HSS has been in the 0.2%-1.4% range over the last year (mean 0.7%). In published retrospective and prospective studies of hip arthroplasty performed at HSS over the last decade, the rate of PE has ranged from 0.5% to 1.7% and proximal DVT has been detected in approximately 4% of patients (range 1.7-22%, the high end detected by MRV)    . Patients in these studies have been treated using a "risk stratification" approach in which "high risk" patients receive warfarin, and "low risk" patients receive aspirin. All surgeries were performed under hypotensive epidural anesthesia. (Intra-operative heparin administration before femoral preparation, minimization of femoral vein occlusion, and preheating of the femoral stem to shorten cement polymerization time are other techniques used by surgeons at HSS to lower the rate of postoperative VTE.) These rates are comparable to those found in the outside literature in which all patients are treated with either warfarin or LMWH postoperatively. Therefore, "low risk" patients undergoing unilateral hip arthroplasty under hypotensive epidural anesthesia at HSS can be given aspirin, warfarin, or LMWH as VTE prophylaxis postoperatively. "High risk" patients (defined below) should receive warfarin or LMWH. Intermittent pneumatic compression (IPC) is recommended as an adjunctive measure in all patients. Future studies will investigate reliable means of stratifying patients into high and low VTE risk groups, incorporating our growing understanding of the genetics and functional characteristics of thrombophilia and hypofibrinolysis.
Suggestions for VTE prophylaxis following THR:
The lowest rates of proximal DVT following TKR are seen in patients treated with either IPC or LMWH 5. In uncomplicated unilateral TKR, the rate of postoperative proximal DVT in patients treated with IPC may be as low as 0%  . This modality is not associated with excess bleeding complications, and it can be used with an epidural catheter in place. Therefore, IPC should be the cornerstone of VTE prophylaxis following TKR. Because IPC cannot be continued after discharge from the hospital, however, concomitant pharmacological anticoagulation of some type is recommended in all patients. In addition, the efficacy of IPC is related to its proper use. It is imperative that all involved in the care of patients understand the central role of IPC as it relates specifically to VTE prophylaxis following TKR.
Suggestions for VTE prophylaxis following TKR:
Given that aspirin and warfarin are not therapeutic options during the time between surgeries in patients undergoing staged bilateral arthroplasty (who are at high risk for VTE), LMWH is the treatment of choice during that period. IPC should be used immediately postoperatively. LMWH should then be started 12-24 hours following the first surgery (assuming adequate surgical hemostasis). There should be clear communication between the physician ordering LMWH and the anesthesiologist, so that the patient’s epidural catheter is removed at least two hours prior to institution of LMWH. LMWH should be discontinued 24 hours prior to the second surgery so as to avoid the risk of epidural hematoma (see guidelines under "Regional Anesthesia"). Following the second surgery, patients should receive either warfarin or LMWH, along with IPC.
In the absence of pharmacological prophylaxis, the rate of PE following hip fracture is 4-24%, and fatal PE 3.6-12.9%. These numbers improve dramatically when any form of pharmacological prophylaxis is used. Aspirin is less efficacious than warfarin or LMWH as VTE prophylaxis following hip fracture . In a study of 13,356 hip fracture patients randomized to aspirin or placebo (in addition to usual care, which included heparin in 44% of patients), aspirin did significantly reduce the risk of clinical VTE, and caused a 50% reduction in fatal PE compared to placebo. Other vascular deaths were higher in the aspirin treated group, however, so total mortality was not reduced .
Factors that add to risk for VTE in hip fracture patients, in addition to those listed previously (i.e. age over 65 with comorbidity, stroke/paralysis, prior DVT, family history VTE, cancer and its treatment, obesity (BMI greater than 30), venous insufficiency, cardiac dysfunction, indwelling central venous catheters, nephrotic syndrome, estrogen/SERM, smoking, thrombophilia/hypofibrinolysis) include:
Elderly patients with hip fracture represent a particularly debilitated cohort. Many are admitted from nursing facilities, and many suffer from dementia. As a consequence, some physicians consider them poor candidates for anticoagulation.
Unfortunately, these same patients are at high risk for VTE by virtue of their age and comorbidity. Most debilitated elderly patients are discharged to a supervised facility, however, where they can continue to be monitored closely by a physician while receiving either warfarin or LMWH. Patients who are felt to be at high risk for bleeding on warfarin or LMWH can be given aspirin as an alternative if it is not contraindicated. Those patients with hip fracture who cannot receive any form of pharmacological prophylaxis should receive an IVC filter.
Patients with hip fracture in whom surgery is delayed are at very high risk for VTE. They may also be at increased risk for bleeding, however, secondary to recent trauma. If it is known in advance that there will be a greater than 24-hour delay before surgery then patients with hip fracture should be treated with LMWH prior to surgery (assuming there are no contraindications to anticoagulation). Because a fresh fracture site may be prone to bleeding, both the injured limb and the hemoglobin level should be monitored carefully when LMWH is used preoperatively. LMWH should be discontinued 24 hours prior to surgery if it is to be done under epidural anesthesia (see guidelines under "Regional Anesthesia").
Suggestions for VTE prophylaxis in patients with hip fracture:
Spine Surgery (Modified June 4, 2004)
Patients undergoing complex spine surgery represent a group at high risk for VTE in whom anticoagulation in the early postoperative period is generally contraindicated because of the risk of epidural hematoma. Patients undergoing spine surgery at HSS experience PE at a rate similar to that seen in patients undergoing hip or knee arthroplasty who are receiving prophylaxis. Doppler studies may be insensitive to clot in these patients since they may occur preferentially in the veins of the pelvis. IPC may be relatively ineffective in these patients for the same reason. At present there is insufficient data on which to base recommendations for the optimal management of these patients. Studies are planned at HSS to address this issue. Meanwhile, recommendations for adult spine patients include the following:
Knee Arthroscopy (formulated March 26, 2004)
The prevalence of deep vein thrombosis (DVT) following knee arthroscopy is approximately 8%. Ninety-nine percent of these clots are distal     . Clinically evident postoperative pulmonary embolism (PE) following knee arthroscopy is rare, but does occur. Because of the relatively low rate of postoperative VTE, prophylaxis cannot be mandated in all cases. Studies suggest, however, that there are surgical and clinical risk factors that can be used to identify patients at higher than average risk for postoperative VTE following knee arthroscopy     .
The term "knee arthroscopy" encompasses a wide variety of surgical procedures ranging from simple knee "washout", or meniscectomy, to ligament repairs and other procedures involving bone drilling. These differences in surgical invasiveness, as well as differences in tourniquet use/duration, type of anesthesia, and duration of postoperative immobility, are important "surgical" risk factors to consider, in addition to clinical "patient" risk factors, in assessing the likelihood of postoperative VTE.
There is a paucity of data on effective VTE prophylaxis for patients undergoing knee arthroscopy. Two studies suggest that postoperative low molecular weight heparin (LMWH) reduces the risk of postoperative DVT by 78-90%  Warfarin has not been studied as VTE prophylaxis following arthroscopy, and is impractical for short-term use in the outpatient setting. There are no studies of aspirin for VTE prophylaxis following knee arthroscopy. Aspirin can, however, be efficacious in reducing the risk of VTE following other orthopedic procedures. 
Suggestions for VTE prophylaxis in patients undergoing knee arthroscopy:
Patients on the medicine service should receive VTE prophylaxis if risk factors are present, including:
The risk of VTE is elevated for up to 12 weeks following orthopedic surgery. Our current system of data collection documents only those PE that occur in the hospital or that randomly come to the attention of the patient care department. In future, a system should be implemented to better capture clinical VTE events occurring in patients during the three months following their discharge from HSS.
When pulmonary embolism occurs in a patient after discharge from the hospital, the event should be reported to the Patient Care Quality Management Department by calling (212) 774-2917. We hope to simplify reporting by establishing an electronic link to that department through the HSS website.
The Committee on DVT/PE Prophylaxis will continue to meet periodically to monitor the rate of VTE at HSS, and to review newly available literature on VTE prophylaxis. The committee will recommend changes in policy when and if new data warrants it.
Finally, because guidelines are only useful if they are followed, a program of ongoing education directed toward physicians (attending and resident staff), nurses and patients is recommended in order to implement the recommendations made above.
 Huo, Salvati, Sharrock, et al. Intraoperative Heparin Thromboembolic Prophylaxis in Primary Total Hip Arthroplasty. Clin Ortho Rel Research 274:35-46, 1992.
 Westrich, Farrell, Bono et al. The Incidence of Venous Thromboembolism After Total Hip Arthroplasty. J Arthroplasty 14:456-463, 1999.
 DiGiovanni, Restrepo, Della Valle et al. The Safety and Efficacy of Intraoperative Heparin in Total Hip Arthroplasty. Clin Ortho Rel Research 379:178-185, 2000.
 Ryan, Westrich, Potter, et al. Effect of Mechanical Compression on the Prevalence of Proximal Deep Venous Thrombosis as Assessed by Magnetic Resonance Venography. J Bone Joint Surg 84-A:1998-2004, 2002.
 Geerts, Heit, Clagett et al. Prevention of Venous Thromboembolism. CHEST 119:132S-175S, 2001.
 Haas, Insall, Scuderi et al. Pneumatic Sequential-Compression Boots Compared with Aspirin Prophylaxis of Deep-Vein Thrombosis after Total Knee Arthroplasty. J Bone Joint Surg 72-A:27-31, 1990.
 Westrich, Sculco. Prophylaxis against DVT after TKR: Pneumatic Plantar Compression and Aspirin Compared with Asprin Alone. J Bone Joint Surg 78-A:826-834, 1996.
 Todd, Freeman, Camilleri-Ferrante et al. Differences in Mortality after Fracture of Hip: the East Anglian Audit. BMJ 31:904-908, 1995.
 Pulmonary Embolism Prevention (PEP) Trial Collaborative Group. Prevention of Pulmonary Embolism and Deep vein Thrombosis with Low Dose Aspirin: Pulmonary Embolism Prevention (PEP) Trial. Lancet 355:1295-1302, 2000.
 Williams JS et al. Incidence of Deep Vein Thrombosis After Arthroscopic Knee Surgery: A Prospective Study. Arthroscopy (1995) 11:701-705.
 Durica S: Abstract presented at Thrombosis and Haemostasis meeting in Milan 1997. Unpublished. Cited in Muntz, JE. The Risk of Venous Thromboembolism in Non-Large-Joint Surgeries. Orthopedics (2003) 26:s237-s242.
 Demers C et al. Incidence of Venographically Proved Deep Vein Thrombosis After Knee Arthroscopy. Arch Intern Med (1998) 158:47-50.
 Jaureguito JW et al. The Incidence of Deep Venous Thrombosis After Arthroscopic Knee Surgery. Am J Sports Med (1999) 27:707-710.
 Delis KT et al. Incidence, Natural History and Risk Factors of Deep Vein Thrombosis in Elective Knee Arthroscopy. Thromb Haemost (2001) 86:817-821.
 Wirth T, et al. Prevention of Venous Thromboembolism After Knee Arthroscopy With Low-Molecular weight Heparin (Reviparin): results of a Randomized Controlled Trial. Arthroscopy (2001) 17:393-399.
 Michot M et al. Prevention of Deep-Vein Thrombosis in Ambulatory Arthroscopic Knee Surgery: A Randomized Trial of Prophylaxis With Low-Molecular Weight Heparin. Arthroscopy (2002) 18:257-263.
Originally published July 2003.