DVT and PE

Pathophysiology, prophylaxis, treatment

Anton Sharapov

Cases to consider 38 yom for elective IHR 65 yom for elective IHR 65 yom, obesity/CHF/prev DVT for IHR 25 yof post severe head injury 25 yom post trauma/abdo/chest 75 yof post hip # 65 yom post THA, obese

Scope of the problem

PCommon postop complicationPAsymptomatic > symptomaticPDifficult to studyPMost studies evaluate asymptomatic pts

Epidemiology VTE 48:100,000 PE 69:100,000 Incidence – 20-70% surgery pts ½ begin in OR

Epidemiology DVT and PE – different stages of same

disease process 10% proximal DVTs progress to

symptomatic PE 25% distal DVTs become proximal

OutcomesP Most asymptomatic VTE recover

sans treatment and complicationsP Less then 1 in 8 confirmed clots

progress to symptomatic thromboembolic disease

P Important to observe clots over a period of time

Outcomes of PE Outcomes of PE are difficult to assess Registry estimates are always higher

then in clinical studies (7% vs 2%) Mortality is a function of RV function,

clot burden, and comorbidities Risk of fatal PE greatest 3-7 postop Asymptomatic PE are common

40% of asymptomatic prox DVTs

AssessmentP Assess risk of DVT and risk of

bleedingP Assess duration of prophylaxisP Assess Virchov triad

P Venous stasisP Endothelial injuryP hypercoagulability

Risk factors: venous stasisPImmobility & tourniquet applicationPInstitutionalizationPCVAPParalysisPCHFPTravel >4 hoursPObesityPRespiratory failurePVaricose veinsPDuration/extent of postop immobilization

Risk factors: endothelial injury Trauma Atherosclerosis Perioperative Malignancy Post-phlebitic syndrome Prior DVT CV catheter Inflamatory condition Hyperhomocysteinemia

Risk factors: hypercoagulability, Acquired

Post op Malignancy Hormone replacement Estrogen therapy

Risk factors: hypercoagulability, Acquired: Antiphospholipid antibody Lupus anticoagulant – 5-10 fold risk Myeloproliferative d/o Paroxysmal nocturnal

hemoglobinuria Nephrotic syndrome Pn loosing enteropathy

Risk factors: hypercoagulability, Inherited:

Factor V leiden – APC resistanceB Absolute risk post op VTE is small - 1/100B Relative risk increased (3-5 fold)B Screening not recommended

Antithrombin, pn C/S deficiency Fibrinogen/TPA defects Prothrombin gene mutation

Risk factors: MiscelaneousP Use/nonuse of thrombopophylactic measures Age - rises linearly after 40

P Ethnicity: Asian/South Pacific - threefold lower African American - slightly higher Latin - slightly lower

Site/extent traumatic injury Knee/spine=major trauma>hip>uro/gyny>

neuro>general/thoracic

Risk of DVT, miscellaneousP Surgical procedure - most important

Neurosurgery & ortho - 6% & 3%

Major vascular

Bowel, bladder, gastric bypass and kidney transplant

Radical neck, IHR, lap chole (0.3%),TURP, thyroid/parathyroid - lowest risk

Need for global integrative assessment American College of Chest

Physicians Risk stratification tool Problems:

What defines major vs minor surgeries? No weighting of Risk Factors Why age 40 and 60 important?

Patient RF Surgical procedure

DVT PE

low Age<40No RF

minor 2% 0.2%

mod

Age>40ImmobilizationObesityMalignancy

GeneralNeuroUro/gyn

20%30%40%

2-3%

high

Hx of DVTThrombophilia

HipKneeSpineTrauma

50%60%60%60%

5%

Risk of bleeding

PBleeding d/oPUse of antiplatelet medsPPrevious GI bleedPCancerPHepatic/renal insufficiencyP?age

VTE prophylaxis: what’s available? Intermittent compression devise Stockings ASA 80-325 mg UF heparin 5000 bid, tid LMW bid Warfarin Anti – Xa pentasaccharide

(fondaparinix)

Efficacy of mechanical VTE prophylaxis

Mode ↧ VTE ↥bleeding

StockingsIPC bootsIVC filter

50-60%50-60%↧PE,↥DVT

NoneNoneProcedure related

Early ambulation Routine for all pts Acceptable as sole mode for low

risk Useful adjunct esp post knee/hip

surgery

Elastic stockings First shown to work in 1952 Decrease venous pooling Evidence of benefit for mod/high

risk, but used only as adjunct Harmful if not work correctly

ICD Work very well Not useful form BMI >25 Only effective if used correctly and

continuously when pt not ambulating Have potential to reduce ambulation Recommended in mod-high risk gyn surgery

as solo Not recommended as sole mode in

Highest risk – except neurosurgery High risk urological Hip and knee surgery

IVC For absolute contraindication of

anticoagulation For life-threatening hem on AC For failure of AC Used to prevent fatal PE Temporary filters preferred If left in place, cause DVTs

Efficacy of pharmacological VTE prophylaxis

mode ↧ VTE ↥bleeding

ASAUF heparinLMW heparinWarfarin

0-50%40-75%50-75%20-60%

50%60-70%50-100%<10%

Aspirin Not recommended as sole

prophylaxis Beneficial post hip-fracture

160 mg OD, 5/52, 13,000 pts Combined with routine prophylaxis PE – 0.7 vs 1.2 Fatal PE 18 vs 43

UF heparin Good for moderate risk gen

surgery Modest increase in bleeding

Compared to LMWH (2.65% vs 1.8%) Additive effect of stockings and

ICD] Risk of HIT

warfarin For very high risk with lower extremity

orthopedic and neuro surgery For gen surgery other methods work just

as well… Good for extended prophylaxis Delayed onset of action, may start preop! Recommended for

Hip #, THA, TKA

LMW heparin and Pentasaccharideds Preferential inhibition of factor Xa FDA approved for DVT prophylaxis Not FDA approved as of yet for

DVT prophylaxis in pregnancy, spinal cord injury, trauma, neurosurgery… but are being used

LMW heparin and Pentasaccharideds cont’d Effective for mod risk general surgery Gyn/obs

second line to mechanical Trauma

Method of choice only if risk of bleeding is not significant. If it is – stocking+/-ICD

Recommended for ortho lower extremity surgery

Fondoparinix reduces asymptomatic DVTs only…

LMW heparin and Pentasaccharideds cont’d

Risk of epidural hematoma Strategies

Avoid regional anesth in those prone to bleed Needle in 12 h after onset of LMWH Single dose anesthetic better then infusion D/c cath in 12 h No dosing of LMWH within 2 h of cath d/c

Direct thrombin inhibitors Effective in initial studies Comparable to LMWH For HIT pts

Duration of prophylaxis Start immediately after or prior to

surgery 7-10 days post Warfarin may be started 10/7 prior but

INR should be less then 1.5 Argument for prolonged (30 day)

prophylaxis for high risk. DVT incidence sympt – 3% vs 1% on treatment Asympt – 19% vs 9% on treatment

Prolonged prophylaxis Orthopedics

Post THA for 4-6 weeks with LMWH or warfarin, especially with Risk Factors

Obesity, sedentary, prior DVT General surgery

Prolonged treatement with LMWH prevents out-pt DVTs but at a marginal cost that was deemed inappropriate

Screening for DVT? Not in the asymptomatic pts….

Diagnostic strategy of DVT Suspect Dupplex For proximal or ANY symptomatic –

treat For distal AND asymptomatic –

follow with serial duplex US

Accuracy of Tests for Diagnosis of PE Clinical suspicion is paramount

test sensitivity specificityHigh Prob VQ

41% 97%

Spiral CT 91% 93%D-Dimer 90-100% 25-60%

Diagnostic strategy for PE Suspect VQ If normal AND D-Dimer low – ruled

out If high probability – start treatment If indeterminate/nondiagnostic –

angio, angio CT

Treatment IV heparin, aPTT 1.5- 2.3 normal 5/7 May use LMW Coumadin INR 2-3 Overlap heparin and warfarin 4/7 On warfarin 3-6/12 Consider ECHO/trop to evaluate RVF

for PE to id High Risk pts.

Treatment Hemodynamically unstable PE may

require pressure support, fluid status monitoring, and/or thromolysis / surgery

Cases to consider 38 yom for elective IHR

None, low risk 65 yom for elective IHR

Moderate risk, Consider UN heparin pre-op, ambulation, stockings post op

50 yom, obesity/CHF/prev DVT for IHR High risk, consider LMWH preop/post op. Conisder

warfarin

Cases concluded 25 yof post severe head injury

High risk, mechanical, 25 yom post trauma/abdo/chest

High risk, mechanical initially, consider LMWH when risk of bleeding is low

75 yof post hip # High, consider LMWH periop, warfarin or aspirin post op

65 yom post THA, obese High, consider LMWH periop, warfarin or aspirin post op