dvt current concept
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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
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