DVTDVTCurrent ConceptsCurrent Concepts

Dr Saeed Al-ShomimiKing Fahad Hospital of University

Khobar – Saudi Arabia2005

Venous Thromboembolism

StasisStasis

Activation of CoagulationActivation of Coagulation

Vessel DamageVessel Damage

Virchow's Triad

Etiology

FREQUENTLY ENCOUNTEREDFREQUENTLY ENCOUNTERED

Prolonged fever + recumbency Lengthy major surgery Orthopaedic / Urologic Massive trauma Pregnancy Long standing v.vs hepatitis

ETIOLOGY

Obscure ZonesObscure Zones

AnesthesiaAnesthesia

general anesthesia have a 5X increased risk of DVT compared with patients receiving epidural anesthesia for the same surgical procedure.

Blood surface antigensBlood surface antigens

Type A blood is associated with lower levels of antithrombin III and higher levels of factor VIII than type O blood.

Women of reproductive age with type A blood are 4 times as likely to develop DVT.

This association of risk with blood type A does not extend to older men or to women past reproductive age

CancerCancer

Malignancy is an important risk factor for DVT, and spontaneous DVT without an obvious cause is an important marker for possible occult malignancy.

In 38% of cases of concomitant cancer and DVT, the DVT is detected first.

The relative risk for cancer is 19 times higher for patients younger than 50 years who have had DVT than for those without a history of DVT.

16% of patients with angiographically proven PE are diagnosed with cancer within 2 years.

Strokes and neurotraumaStrokes and neurotrauma

common after stroke or neurological trauma.

Without prophylaxis, half the patients develop acute DVT within 5 days following a stroke.

Head trauma may cause disseminated intravascular coagulation, and DVT.

40% of postoperative neurosurgical patients develop DVT.

Stroke patients with a single paretic leg develop DVT in 60% of the paralyzed legs but in only 7% of the nonparalyzed ones.

ChemotherapyChemotherapy

Many types of chemotherapy increase the risk of DVT and PE

↓ the levels of circulating anticoagulants such as antithrombin III or protein C or S

↑procoagulants such as von Willebrand factor

depress fibrinolytic activity.

Coagulopathy Coagulopathy

Protein C Protein S Antithrombin III

15% of the cases of DVT

Heart diseaseHeart disease Acute MI and CHF increase the likelihood of

DVT and PE, independent of bed rest or immobilization.

Patients with acute MI who are not receiving anticoagulation have a 26-38% rate of DVT.

Inflammatory bowel diseaseInflammatory bowel disease

Patients with ulcerative colitis or Crohn disease are at increased risk for DVT and PE because of increased fibrinogen, factor VIII, and platelet activity and depressed levels of antithrombin III and alpha2-macroglobulin.

Prior DVTPrior DVT Patients with a prior episode of DVT are 5 times

more likely to develop new DVT compared with patients with no prior episodes of DVT.

Prior DVT increases the risk of new postoperative DVT from 26% to 68%.

A history of prior clinically apparent PE increases the risk of new postoperative DVT to nearly 100%.

Autoimmune VasculitisAutoimmune Vasculitis

Behcet’s disease Lupus antibodies Anticardiolipin AB Antiphospholipid AB ASMC AB

Especially in young with no

apparent cause

INVESTIGATIONS

LABLAB

PT ,PTT , INR ESR D-dimer ABG Protein C , S Antithrombin III

RADIOLOGYRADIOLOGY

ULTRASOUND (Duplex) VENOGRAPHY (rarely used) MRV ventilation-perfusion scanning ( for PE ) Nuclear venography

MANAGEMENT

GENERAL MEASURESGENERAL MEASURES

1- Complete bed rest

2-The affected extremity should be elevated above the level of the heart until the oedema and tenderness subside .

Anticoagulants Thrombolytics Prophylaxis

I-AnticoagulantsI-Anticoagulants

Anticoagulants prevent thrombous propagation & allow endogenous lytic system to operate.

Aim :prevention of pulmonary embolism , since in the early stages the thrombus maybe loose & poorly adherent to the vessel wall.

ContraindicationContraindication

1-recent surgery, especially to eye or CNS.2-Pre_existing hemorrhagic state e.g. Liver ds Renal Failure Hemophilia Thrombocytopenia3-Pre_existing structural lesions e.g. Peptic Ulcer4-Recent cerebral hemorrhage.5-Uncontrolled HPN.

11--HeparinHeparin

Mech. Of actionMech. Of action Standard Heparin (SH)Standard Heparin (SH)

produces its anticoagulant effect by potentiating the activity of anti-thrombin which will inhibit procoagulant enzymatic activity of factors IIa ,VIIa ,IXa ,Xa ,XIa.

LMWH LMWH augment anti-thrombin activity against factor Xa.

Advantages of LMWH over SHAdvantages of LMWH over SH

1-LMWH has a high bioavailability after SC injection so its given either as a fixed or weight-related dose .Therefore ,The plasma LMWH level does not need to be measured.

2-The incidence of thrombocytopenia is less with LMWH than SH.

3-LMWH is reported to be as effective as or better than SH in preventing extension or recurrence of venous thrombosis.

Route of Admn. & Dose

Heparin…(IV) as an initial bolus of 7500 to 10,000 IU followed by a continuous infusion of 1000 to 1500 IU/h.

The rate of heparin infusion should be adjusted so that the active aPTT is approximately twice the control value.

S/E…in less than 5% of patients ,heparin therapy may cause thrombocytopenia. Infrequently ,these pt develop arterial thrombosis & Ischemia

22--WARFARINWARFARIN

Mech. Of action.. Warfarin inhibit vit K-dependant

carboxylation of factors II ,VII ,IX ,X in the liver.

Warfarin is administered during the 1st wk of treatment with heparin &maybe started as early as the 1st day of heparin treatment if the aPTT is therapeutic.

Why to overlap Heparin ttt with oral anticoagulant therapy??

This because of the delayed effect of warfarin.

SO…Overlap is important for at least 4-5 days

Dose of warfarin should be adjusted to maintain the thrombin time at an INR of 2-3

Duration of anti-coagulant therapy

1st attack 3 M

2nd attack 1 year

3rd attack Life

BUT…What if treatment with anti-BUT…What if treatment with anti-coagulant is contraindicatedcoagulant is contraindicated??????

IVC filter.

II-ThrombolyticsII-Thrombolytics

StreptokinaseUrokinaseTissue Plasminogen

Activator

There is no evidence that thrombolytic therapy is more effective than anti-coagulants in preventing pulmonary embolism!!

HOWEVER…early administration of thrombolytic drugs may accelerate clot lysis .

III-ProphylaxisIII-Prophylaxis

ALL PATIENTS ADMITTED TO HOSPITAL SHOULD BE ASSESSED FOR THEIR RISK OF VENOUS THROMBOSIS.

Mechanical:Mechanical: -early mobilization

-leg raising.

- graduated compression (TED) stocking.

DrugsDrugs (anti-coagulants).

Moderate risk of DVTHigh risk of DVT

Major surgery in patient>40 years or with other risk factorMajor medical illness

e.g. heart failure

chest infection

malignancy

inflammatory bowel disease

Hip or knee surgery Major abdominal or pelvic surgery for malignancy or with history of DVT

Category Frequency of Calf Vein Thrombosis

Frequency of Proximal Vein Thrombosis

Frequency of Fatal PE

High-risk 40-80% 10-30% >1%

Moderate-risk

10-40% 1-10% 0.1-1%

Low-risk >10% >1% >0.1%

Anti-coagulantsAnti-coagulants

Heparin(5000 units 2h prior to surgery then 5000 units every 8-12h post operatively) reduces the risk of DVT ass. With thoracic & abdominal surgery & with prolonged bed rest.

LMWHs have been shown to prevent DVT in pt undergoing general or orthopedic surgery.

Warfarin in a dose that yields apt equivalent to an INR of 2-3 is effective in preventing DVT ass. With bone fractures & orthopedic surgery.

Warfarin is started the night before surgery & continued.

BUT..WHAT IF THE ANTICOAGULANT IS C/I???

External pneumatic compression devices applied to the legs are used to prevent DVT when even low doses of heparin or warfarin might cause serious bleeding ,as during neurosurgery or transurethral resection of the prostate

What Is New ?

PREVENTION AND TREATMENT OF VENOUS

THROMBOEMBOLISM

International Consensus Statement

(Guidelines according to scientific evidence)

(Int. Angiol., June 2006)

64 international vascular experts 52 major centers worldwide DVT Registry 2001 – 2005 Meta – analysis of 116 studies Prevention and treatment policies

International Consensus Statement

Reviewed/modified

GENERAL AND VASCULAR SURGICAL PATIENTS

THE RISKTHE RISK

Known clinical risk factors allow for classification of patients into high, medium or low risk of developing VTE

the risk continues after discharge from hospital.

Despite the use of intra-operative heparin or other perioperative antithrombotic substances, vascular surgical patients are at moderate risk

The incidence of postoperative asymptomatic DVT is of the order of 18% in patients having abdominal vascular

surgery 15% for those having peripheral vascular

reconstruction The risk of VTE in patients undergoing

laparoscopic surgery appears to be low.

Obesity is an independent risk factor for sudden post-operative fatal PE.

Bariatric surgery is associated with clinical VTE in 1.2% of cases and with fatal PE in 0.3%.

ProphylaxisProphylaxis

low dose unfractionated heparin (LDUH) (5000 IU 8 or 12 hourly subcutaneously) was

found to reduce both DVT and fatal PE LMWH

not only reduces the incidence of fatal PE but also the overall surgical mortality as compared to controls without prophylaxis.

dextrandextran The preventive effect of dextran on fatal PE

has been updated and verified. It appears that fibrin formed in the presence of dextran is not cross-linked so that it is easily lysed by the body’s natural fibrinolytic activity.

fluid overload and anaphylactoid reactions

Graduated elastic compression (GEC) Graduated elastic compression (GEC) stockings reduce the incidence of

asymptomatic DVT by approximately 50-60%

Intermittent pneumatic compression Intermittent pneumatic compression (IPC)(IPC) reduces the incidence of asymptomatic DVT

by approximately 69%

AspirinAspirin reduces DVT by 30% and PE by 50%

Combined modalities.Combined modalities. Evidence from randomized controlled

studies shows that combinations of prophylactic methods are more effective than using each method

RecommendationsRecommendations

Low-risk patientsLow-risk patients (without risk factors undergoing minor

surgery.)

GEC stockings early ambulation adequate hydration

Moderate-risk patientsModerate-risk patients

(over the age of 40 years undergoing major

surgery for benign disease ( LDUH 5000 units commenced pre-

operatively and continued 2X -3X daily

OR LMWH initiated and dosed according to

manufacturers

If Bleeding Risk: IPC with GEC compression used

continuously until the patient is ambulant

High- risk patientsHigh- risk patients (aged over 60 years with additional risk

factors( LDUH (5000 units commenced two hours

before operation and continued post-operatively three times a day)

OR LMWH initiated and dosed according to the

manufacturer’s recommendations

Laparoscopic surgery for major prolonged procedures will reduce venous flow in the legs and activate blood coagulation.

Prophylactic subcutaneous LDUH, LMWH, or IPC with GEC are recommended only in patients with additional risk factors

BURNS

THE RISKTHE RISK

The incidence of DVT using routine screening with duplex scanning in the absence of prophylaxis varies between 6% and 27%

Symptomatic VTE occurs in in 2.4% to 7.0% of patients.

RecommendationsRecommendations

Drug: LMWH

Initiation: as soon as it is considered safe to

do so Duration:

as long as the patient remains at risk

CANCER PATIENTS

THE RISKTHE RISK

The risk of thromboembolic disease varies by type of malignancy 120 per 10,000 patients for ovarian

malignancy 117 per 10,000 for primary brain

malignancy 110 per 10,000 for pancreatic cancer

In OR the risk is 2X compared to Normal Patient

patients receiving chemotherapy appear to have a therapy-associated increased rate of VTE

tumor and stage-dependent. Patients who received radiotherapy had a

higher frequency of VTE within three months of therapy and surgery compared with those who did not

PROPHLAXISPROPHLAXIS

Surgical patients LDUH reduces the risk of DVT and fatal PE

in patients with malignancy having surgery LMWH is at least as effective as LDUH. Continuation of LMWH for four weeks after

discharge home reduces the risk of asymptomatic DVT as demonstrated by venography from 13.8% to 5.5%

Medical cancer patients LMWH is effective for preventing

thromboembolic disease associated with acute medical illness

in 311 patients with metastatic breast cancer receiving chemotherapy randomised to low dose warfarin (INR between 1.3 and 1.9)

Patients receiving radiotherapy Although patients who receive radiotherapy

have a higher frequency of VTE within three months of therapy and surgery compared with those who do no

there are no studies on the value of routine thromboprophylaxis in those receiving radiotherapy. Such studies need to be performed

with central venous catheters cancer patients with central venous catheters

have a high frequency for development of VTE

The use of LMWH (Dalteparin sodium 2500 units once daily) has been shown to be effective in reducing venographic thrombosis from 62% to 6%

Warfarin (1mg per day) has been shown to be effective in reducing all venographic thrombosis from 37% to 9.55

RecommendationsRecommendations

Surgical: LDUH (5000 IU 8-hourly commenced prior

to operation) LMWH

For patients at high risk for development of thromboembolic disease in the post-discharge period those with large volume residual malignant

disease previous history of venous thromboembolic

disease) prolonged thromboprophylaxis with

enoxaparin 40mg once daily for up to 4 weeks after operation should be considered

In ambulant non-surgical cancer patients, data are available only for those with advanced breast cancer receiving chemotherapy In these patients,

use of vitamin K antagonists to maintain an INR of between 1.3 and 1.9 may be considered

For cancer patients hospitalised with acute medical illness, thromboprophylaxis should be based on the risk for VTE determined by the acute medical co-morbidity. LMWH LDUH should be used (5000 IU 8-hourly)

For cancer patients with central venous catheters, routine use of thromboprophylaxis to prevent central venous catheter associated thrombosis is not recommended

MULTIPLE TRAUMA

THE RISKTHE RISK

The incidence of DVT in patients who have sustained major trauma is in excess of 50%

PE is the third leading cause of death in those who survive beyond the first day

The risk is particularly high in patients with spinal cord injury, pelvic fracture and those needing surgery

RecommendationsRecommendations

LMWH starting as soon as bleeding risk is acceptable

or IPC in the presence of contraindications to LMWH and continued until full ambulation.

THANK YOUTHANK YOU