Thromboprophylaxis in surgical patients

Surgical Biology for the Clinician
Biologie chirurgicale pour le clinicien
Thromboprophylaxis in surgical patients
Martin O’Donnell, MB; Jeffrey I. Weitz, MD Venous thromboembolism is the most common preventable cause of death in surgical patients. Throm-boprophylaxis, using mechanical methods to promote venous outflow from the legs and antithromboticdrugs, provides the most effective means of reducing morbidity and mortality in these patients. Despitethe evidence supporting thromboprophylaxis, it remains underused because surgeons perceive that therisk of venous thromboembolism is not high enough to justify the potential hemorrhagic complicationsof anticoagulant use. The risk of venous thromboembolism is determined by patient characteristics andby the type of surgery that is performed. In this paper we identify the risk factors for venous throm-boembolism and provide a scheme for stratifying surgical patients according to their risk. We describethe mechanism of action of the various forms of thromboprophylaxis and outline the evidence support-ing thromboprophylaxis in different surgical settings. Finally, we recommend optimal forms ofthromboprophylaxis in patients who undergo various types of surgery. Intermittent pneumatic compres-sion, with or without elastic stockings, can be used for thromboprophylaxis in patients who undergoneurosurgical procedures; for patients who undergo vascular or cardiovascular procedures, long-termacetylsalicylic acid should be used for thromboprophylaxis. Low-molecular-weight heparin (LMWH) orwarfarin is the choice for patients with spinal cord operations and all patients with major trauma who donot have contraindications to anticoagulation should receive thromboprophylaxis with LMWH.
La thromboembolie veineuse est la cause de décès évitable la plus courante chez les patients en chirurgie.
La thromboprophylaxie pratiquée par des moyens mécaniques pour promouvoir l’écoulement veineuxdes jambes et l’administration d’antithrombotiques constitue le moyen le plus efficace de réduire la morbidité et la mortalité chez ces patients. En dépit des données probantes à l’appui de la thrombo-prophylaxie, elle est toujours sous-utilisée parce que les chirurgiens croient que le risque de thrombo-embolie veineuse n’est pas assez important pour justifier les complications hémorragiques que pourraitentraîner l’utilisation d’anticoagulants. Le risque de thromboembolie veineuse est déterminé par lescaractéristiques du patient et par le type d’intervention chirurgicale pratiquée. Dans cette communication,nous décrivons les facteurs de risque de thromboembolie veineuse et présentons un programme de strati-fication des patients en chirurgie en fonction du risque. Nous décrivons le mode d’action des diversesformes de thromboprophylaxie et présentons un aperçu des données probantes qui appuient la thrombo-prophylaxie dans différents contextes chirurgicaux. Nous recommandons enfin des formes optimales dethromboprophylaxie chez les patients qui subissent divers types d’interventions chirurgicales. On peut recourir à la compression pneumatique intermittente, avec ou sans bas élastiques, comme thrombo-prophylaxie chez les patients qui subissent des interventions neurochirurgicales. Dans le cas de ceux quisubissent une intervention vasculaire ou cardiovasculaire, il faudrait utiliser l’acide acétylsalicylique à longterme comme thromboprophylaxie. L’héparine de faible poids moléculaire (HFPM) ou la warfarinereprésentent le traitement de choix dans le cas des patients qui subissent une intervention chirurgicale à lamoelle épinière et tous les patients qui ont subi un traumatisme majeur et qui ne présentent pas de contre-indication à l’anticoagulation devraient recevoir une thromboprophylaxie à l’HFPM.
Venous thromboembolism (VTE), talized patients. It is estimated that highlighting the fact that fatal PE From the Henderson Research Centre and McMaster University, Hamilton, Ont.
Accepted for publication June 11, 2002.
Correspondence to: Dr. Jeffrey Weitz, Henderson Research Centre, 711 Concession St., Hamilton ON L8V 1C3; fax 905 575-2646;
jweitz@thrombosis.hhscr.org
O’Donnell and Weitz
erative disorders, particularly essential addition to this list is synthetic penta- laxis in high-risk orthopedic patients.
Anticoagulants
Risk stratification for venous
thromboembolism
Thromboprophylactic measures
and their mechanism of action
Risk factors for venous
thromboembolism in surgical
patients
illnesses, obesity, risk factors such asprevious VTE, cancer, age over 60 Venous Thromboembolism (VTE) Risk Stratification in Surgical Patients
lower limb paralysis, use of hormonaltherapy (oral contraceptives or hor- Minor surgery in patients < 40 yr old without risk factors Minor surgery in patients with risk factors Minor surgery in patients 40–59 yr without risk factors Major surgery in patients < 40 yr or with risk factors Major surgery in patients > 40 yr or with risk factors DVT = deep vein thrombosis, PE = pulmonary embolism.
Thromboprophylaxis in surgical patients
General surgery
UFH, and LMWH has a longer Normalized Ratio (INR) of 2–3.
Antiplatelet drugs
persist for the lifetime of the platelets.
and accelerates its rate of Factor Xa in- tiplatelet effect of acetylsalicylic acid is ticlopidine and clopidogrel, irreversibly tion. Because at least half the chains of complications of clopidogrel therapy.
tivity against Factor Xa and thrombin.
given once daily and it is less likely to patients allergic to acetylsalicylic acid.
alyzes Factor Xa inhibition by an-tithrombin but has no effect on the Thromboprophylaxis in various
Subcutaneous Heparin and Low-
Molecular-Weight Heparin
clinical settings
Thromboprophylaxis Dosage
Regimens for Surgical Patients
*Heparin is given in international units (U), whereas low-molecular-weight heparins are given in antifactor Xa units (U).
†Although the dose is in mg, enoxaparin has a specific activity of 100 antifactor Xa U/mg‡When started postoperatively, twice-daily low-molecular-weight heparin or regimens are often prescribed. In contrast, if started preoperatively, once-daily postoperativedosing may be sufficient.
O’Donnell and Weitz
shown the opposite effects. These suitable alternative to parenteral anti- bleeding at the surgical site is slightly General surgery in cancer patients
of LMWH can be given 2 hours without cancer.2 Low-dose UFH and Major orthopedic surgery
laxis in these patients is controversial, of the individual trials included in this tended prophylaxis may be beneficial.
be an effective form of prophylaxis.
the use of warfarin in this setting.
Thromboprophylaxis in surgical patients
Vascular and cardiothoracic
distal DVT in knee surgery patients.
able choices for thromboprophylaxis.
prophylaxis in knee surgery patients.
high risk for postoperative bleeding.
long-term acetylsalicylic acid therapy.
generalized atherosclerotic disease.
with acetylsalicylic acid intolerance.
their clinical relevance is uncertain.
tant trigger for DVT in both settings.
after elective hip or knee arthroplasty.2 quently, there is a trend toward used more often than anticoagulants O’Donnell and Weitz
Recommendations
General recommendations
death in spinal cord injury patients.
Specific recommendations
Thromboprophylaxis in surgical patients
heparin versus standard heparin in general and orthopedic surgery: a meta-analysis.
Lancet 1992;340:152-6.
8. Amarigiri SV, Lees TA. Elastic compres- sion stockings for prevention of deep vein thrombosis. Cochrane Database Syst Rev 9. Antiplatelet Trialistsí Collaboration. Col- laborative overview of randomized trials ofantiplatelet therapy: III. Reduction in ve- nous thrombosis and pulmonary em-bolism by antiplatelet prophylaxis among Acknowledgements: We are indebted to Mrs.
surgical and medical patients. BMJ 1994; S. Crnic for her help preparing the manuscript. Dr. O’Donnell is the recipient of the R.K.
10. Hull R, Raskob G, Pineo G, Rosenbloom Fraser Fellowship in Thrombosis. Dr. Weitz is a Career Investigator of the Heart and StrokeFoundation of Canada and holds the Heart and Stroke Foundation of Ontario/J.F. Mus- tard Chair in Cardiovascular Research and the laxis against deep vein thrombosis after hip or knee implantation. N Engl J Med 1993; References
(PEP) trial [see comments]. Lancet 2000;355:1295-302. Comments in: ACP Journal Club 2001;134:13; Lancet 2000; mortality in hospitalized patients. JAMA 12. Eikelboom JW, Quinlan DJ, Douketis JD.
2. Geerts W, Heit JA, Clagett GP, Pineo GF, Extended-duration prophylaxis against ve- randomised trials. Lancet 2001;358:9-15.
Caprini J, Comerota A, Haines ST, et al.
Szalai JP, Saibil EA, et al. A comparison of weight heparin as prophylaxis against VTEafter major trauma. N Engl J Med 1996; for Surgical Patients. Arch Intern Med 4. Hirsh J. Heparin. N Engl J Med 1991; 14. Agnelli G, Piovella F, Buoncristiani P, Sev- eri P, Pini M, DíAngelo A, et al. Enoxa- 5. Weitz JI. Low-molecular-weight heparin.
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