15 - DVT and PE Flashcards
Thrombus
o Clot composed initially of platelets and fibrin
o RBC’s get interspersed in fibrin with time
Thrombophlebitis
o Presence of thrombus within a vein accompanied by inflammation
Superficial Vein Thrombosis
o Thrombus in superficial vein
o Least serious
Deep Vein Thrombosis (DVT)
o Thrombus in deep vein network
Pulmonary Embolus (PE)
o Thrombus in pulmonary artery
o Can be fatal
Statistics
DVT incidence in US is 2 million people/yr, most commonly in the lower extremity
o Of this 2 million, 0.5-3.5% following foot and ankle surgery
o DVT incidence high in hip and knee surgery if not prophylaxed is 35-60%
PE incidence
o 300,000-600,000 people develop DVT/PE each year (1.8-7% of DVT’s from calf)
o 50,000-100,000 people die from DVT/PE each year (0.2-0.7% of DVT’s from calf)
STUDY - Roukis
More patients treated conservatively have DVT than those treated surgically
Study results
o 5.9 % DVT, 0.03% PE- conservative tx (cast immobilization/bed rest)
o 3.3% DVT, 0.12% PE- surgical tx (surgical intervention)
Most distal rather than proximal
o 92.5% of conservative tx, 85.6% asymptomatic or “silent”
o 88.4% of postoperative, 92.9% asymptomatic or “silent”
Postoperative
o 106 DVT’s – 60.4%-no prophylaxis, 39.6%- prophylaxis
REMEMBER
DO NOT FORGET THAT ANY IMMOBILIZATION CAN RESULT IN DVT, NOT JUST SURGERY
Any calf pain is DVT until proven otherwise
STUDY - Solis and Saxby
Incidence of DVT = 3.5%
Risk factors
- Hindfoot surgery
- Immobilization
- Increase TK time
- Increased age
STUDY - Wukich and Waters
Incidence of DVT = 0.4%
Risk factors
- Age 40+
- NWB for more than 1 week
- Obesity
- Concomitant illness
STUDY - Schade and Roukis
Incidence of DVT = 3.3%
Risk factors
- Immobilization
- Age 40+
- NWB requirement
- Severe injury
- Hindfoot surgery
STUDY - Soohoo
Incidence of DVT = 0.05%
Risk factors
- Age 50-75
- PVD
Consequences of DVT
- Pulmonary Embolism – Potentially deadly
- Recurrent DVT – 1/3 with have recurrence within 10 years
- Post Phlebotic Syndrome (Progressively worsens over time – 50% have long term complications
o Edema, pain, induration, pigment changes due to hemosiderin deposits, ulceration
Anatomy
- Blood passes from superficial to deep veins through perforators
- Valves keep blood from retrograding (Thrombus usually forms at valves)
- Vena cava goes to right side of heart and gets pumped into pulmonary arteries
Virchow’s triad
KNOW THIS
CAUSES OF DVT (this is different from risk factors)
Stasis
o Micro clots form around valves of veins
Hypercoagulability
o Factor V Leiden, antithrombin III, Protein C &S deficiency, Tobacco use, Pregnancy
Endothelial vascular damage
o Exposes subendothelial collagen, promoting platelet aggregation
Coagulation cascade
- Important for boards – entire cascade
- For clinic (real life practice) – just know intrinsic, extrinsic, and what drugs work for each/both
Risk factors for stasis
ast immobilization, Prolonged bed rest - >3 days, Acute MI, CHF, Stroke, Long road trip
Risk factors for vascular damage
o Previous DVT , Trauma, Fractures, Hip or knee replacement, Abdominal surgery
Risk factors for hypercoagulale state
o Cancer, pregnancy, estrogen use, 5-8% have genetic risk factor, factor V Leiden (resistance to activated protein C), deficiency of antithrombin III, protein C or S
Other risk factors
o Age over 40, obesity, prolonged surgery
Podiatric specific risk factors
Assign 1 risk factor for each of the following:
o Operating room time >105 min
o Tourniquet time >90 min
o Rearfoot or ankle surgery
Assign 2 risk factors for each of the following:
o Immobilization in a BK or AK cast for >1 wk
o Medical or surgical patients confined to bed for >72 h
o Central venous access
Assign 3 risk factors for each of the following:
o Ankle/tibia/pilon fracture
Assign 5 risk factors for each of the following:
o Multiple trauma
**DVT hand out KNOW LOW, MODERATE, HIGH RISK **
o Use this information to decide what the appropriate prophylaxis would be
o KNOW DOSAGE, KNOW USAGE
Identifying patients at risk – can present very differently
- 80 y/o pt with ankle fracture, 60 y/o obese pt w/ HTN, hyperlipidemia, undergoing bunion surgery, 44 y/o DM pt with triple arthrodesis, 18 y/o female, on BCP, with ankle fracture, 22 y/o smoker with a septic ankle
DVT Risk - Low (
Age
DVT Risk - Moderate (10-40%)
Age 40-60 or duration >60 min or risk factor
Risk: o Calf DVT: 10-20% o Proximal DVT: 2-4% o Significant PE: 1-2% o Fatal PE: 0.1-0.4%
Tx: ASA, LMWH, SCD/foot pumps, Compression
DVT Risk - High (40%)
Age >60
Age 40-60 with additional risk factor Risk: o Calf DVT: 20-40% o Proximal DVT: 4-8% o Significant PE: 1-2% o Fatal PE: 0.4 – 1.0%
Tx: LMWH, SCD/foot pumps, consider prolonged anticoagulation, compression
DVT Risk - Highest Risk (40-80%)
Age >40 with multiple risk factors or THA, TKA, Hip Fx, Major trauma
Risk: o Calf DVT: 40-80% o Proximal DVT: 10-20% o Significant PE: 4-10% o Fatal PE: 0.2-5%
Tx: Long term anticoagulation, compression
Recommendations
- May need prophylaxis, may not need prophylaxis – those at higher risk may need prophylaxis
WHAT DO YOU DO??????
o Evaluate each patient carefully, develop protocol, and DOCUMENT
o Seek opinion of PCP, internist
DVT Prophylaxis
Mechanical
o Bilateral pneumatic sequential compression device (SCD)
o Foot pumps, graduated compression stockings
o Early mobilization if possible
o Active range of motion of lower extremities if possible
Medical
o LMWH (Lovenox/enoxaprin) – Factor Xa and II inhibitor
o ASA
o Xarelto (Rivaroxaban) – Factor Xa inhibitor (selective)
o Heparin
What to tell patients at risk (“we already went through this”)
- EDUCATE-Watch for signs of DVT postoperatively, discuss ways they can reduce risk of DVT
- Alternative treatment options*
- Mechanical prophylaxis*
- Chemical prophylaxis*
- Review reasons for tx or no tx and DOCUMENT
Signs and symptoms of DVT
- Symptoms peak at day 3-4 (again at 5-6 weeks***) – know that there is a SECOND HIT
- Most common complaint is calf pain (Squeeze calf – might just be normal calf pain from sx)
- Leg swelling
- Positive Homan’s sign??? (passive dorsiflexion, pain in calf, commonly done/pimped on)
- +/- distention of superficial collaterals
- +/- fever/tachycardia
- Unilateral leg edema (calf 2-2.5 cm greater than opposite lower extremity)
- Posterior calf tenderness and increased warmth, generally erythema present
- May get
o Phelgmasia cerulea dolens – Blue hue due to stagnant deoxygenated blood
o Phelgmasia alba dolens – Pallor due to interstitial pressure exceeding capillary - Positive Homan’s sign (pain with passive dorsiflexion of foot, unreliable)
- Pain with calf or thigh compression
- Occasionally get palpable cords (more common with superficial thrombophlebitis)
Differential diagnosis
- Postoperative edema/pain
- Ruptured Baker’s cyst (crepitus on flexing the knee, history of arthritis)
- Muscle or bone pathology ( especially in calf or Achilles tendon)
- PVD, Hematoma, Lymphedema, CHF
Diagnosis of DVT
- More concerned with thigh than calf DVT – 50% of thigh DVT will propagate to PE if untreated
o 20-30% of calf DVT will propagate to thigh - Bedside diagnosis is often inaccurate and unreliable
- The degree of physical signs and symptoms does not correlate with size or extent of clot.
- Must correlate risk factors, history and physical exam, and diagnostic testing
- If any concern, WORK THEM UP!
Laboratory tests
- D-dimer
- Imaging
D-dimer
D-dimer is a degradation product of cross-linked fibrin that is released into the blood during fibrinolysis
Highly sensitive
o Has low specificity
o + with increasing age, infection, inflammation
+ When > 500 ng/ml (but can still be a grey area)
o If it is less than 300 and you have low suspicion, confident that it is NOT a DVT
o If it is 500-700 and you have a low suspicion, keep working it up
o Anything higher, treat it as a DVT and keep working it up
Imaging
Most common = Duplex Ultrasound
Less Common
o Contrast Venogram (historical “gold standard”)
- It is an invasive exam that is NOT done very commonly done
- The test by which everything else is tested against (the best we have)
- Ultrasound can give us the same answer as venogram X amount of time
o Impedance plethysmography (not common)
o MRI, CT , I-125 fibrinogen (not common)
Venous duplex ultrasound
- Thrombus can be visualized by direct visualization or interference when vein does not collapse with compression
- Positive predictive value, 95% for proximal thrombosis, 50-75% sensitivity in calf (due to difficulty with visualization)
Blood work
Platelets – used to assess the platelets if using LMWH or heparin
Coagulation factors – need to figure out if they have a coagulopathy o Factor V Leiden o Protein C and S o Antithrombin III o Plasminogen o Homocysteine o Antiphospholipid antibodies
Internal Med/Hematology Consult for further tests for coagulopathy
Color venous Doppler
Uses standard ultrasound methods to produce image of blood vessel
Computer converts sounds into colors that are overlaid on the image of the vessel
o Represent speed and direction of blood flow
o Flow traveling toward the transducer is red, away is blue
o Faster velocities are displayed in brighter colors
Diagnostic imaging
If ultrasound is positive, patient has DVT
If ultrasound negative, but is at high risk*
o Recheck in several days, consider starting anticoagulation, consider venogram
If venogram negative
o No DVT
If moderate risk and the ultrasound is negative
o Consider repeating scan in one week and withholding anticoagulation
High risk: physical signs and history strongly suggest DVT
DVT treatmetn - physical measures
o Warm, moist heat to increase venous dilation
o Adequate hydration, analgesics, elevation of extremity
DVT treatment - hospitalization
o May require in-patient hospitalization to watch for PE, pharmacologic anticoagulation
o Multi-drug therapy to reach therapeutic dose, may use thrombolytics
o Patients who cannot be anticoagulated may need IVC filter
DVT treatment - anticoagulatns or thrombolytics
Anticoagulants
o Unfractionated Heparin
o Low molecular Weight Heparin (LMWH)
o Coumadin(warfarin)
Thrombolytics
o Streptokinase, Urokinse, tPA
o Is not more effective in preventing PE but can accelerate clot lysis, preserve venous valves, decrease chance of developing postphlebitic syndrome
Pathway for unfractionated heparin (regular heparin)
* INHIBITS INTRINSIC PATHWAY*
Action of heparin
Action
o Binds to antithrombin III which potentiates the inhibition of thrombin (II) and Xa, IXa, XIa, XIIa
o Inactivates thrombin by cofactor II which acts independently of ATIII
Response to heparin varies widely, bleeding returns to normal very quickly upon d/c
Prophylaxis: 500 U SQ TID
Treatmetn with heparin
Treatment: IV bolus of 80 IU/kg then infuse at rate of 18 IU/kg/hour
o Titrate until aPTT is 1.5-2.3 times normal
o Monitor the response by using aPTT (activated partial thromboplastin time)
o Start Coumadin ~12-24 hours after induction of heparin therapy
o Heparin continued until INR (international normalized ratio) 2.0-3.0
Complications of heparin
Uncontrolled bleeding
- Reversed w/ protamine zinc sulfate, stop heparin immediately
Thrombocytopenia (HIT)
- Can be accompanied by arterial or venous thrombosis
- Stop heparin immediately, consider alternative drugs, check platelets 5 days
Low molecular weight heparin (LMWH) – Lovenox
Also known as fractionated heparin (portion of heparin molecule)
Differs from heparin by
o Increased bioavailability, prolonged half-life and predictable clearance
o Predictable antithrombic response permitting treatment without lab monitoring
Most common brands o Lovenox (enoxaparin sodium) o Fragmin (dalteparin sodium) – not common
Interacts only with factor Xa, not thrombin, so pharmacokinetics are predictable
Advantages of lovenox over heparin
o Administered subQ bid/daily, causes much less bleeding and virtually no thrombocytopenia, no lab monitoring
Clinical use of LMWH or lovenox
o Can’t be used in patient wtih heparin-induced thrombocytopenia )cross-reactivity)
o Has virtually replaced heparin in treating DVT and PE
o Start Coumadin 12-24 hours after starting LMWH until INR between 2 and 3 reached
o Check platelets after 5 days due to chance of thrombocytopenia
o Reverse with protamine zinc sulfate (1mg for 1 mg of Lovenox) – return to normal 12 hrs
Coumadin (warfarin) pathway
INHIBITS EXTRINSIC PATHWAY ***
Action of coumadin
Action
o Inhibits Vit K-dependent carboxylation of coagulation factors II, VII, IX, X, as well as, proteins C and S
Produces paradox:
o Proteins C and S have shorter half-life than coagulation factors
o Get depleted faster leading to potential hypercoaguable state
*Bridging therapy
o Heparin/LMWH and Coumadin treatment should overlap by 4 to 5 days when Coumadin treatment initiated for DVT prophylaxis/tx
Other details on coumadin
Peak effect does not occur for 24 to 72 hours after administration
Start treatment at 5 mg/day po
Bleeding takes ~3-5 days to return to normal - NEED to plan ahead for another surgery
Extrinsic pathway
Over 150 drugs interact with Coumadin (metabolized by P 450 enzyme system)
o Potentiate effects of ASA, NSAID’s, Synthroid®, allopurinol, Bactrim
o Decrease effects of oral contraceptives, dicloxacillin, nafcillin
- Raises the level of
o Oral hypoglycemics and anticonvulsants (metabolism or excretion problem)
o Levaquin (kidney clearance problem)
Dosing of coumadin
o Coumadin administered at initial dose of 5 mg/day for the first 2 days
o Daily dose then adjusted according to INR – Usually want INR of 2-3
o LMWH discontinued on 4th or 5th day following initiation of Coumadin therapy, provided INR in therapeutic range of 2 to 3
o Once anticoagulant effect stable, INR should be monitored every 1 to 3 weeks
o Most patients need to be on Coumadin for 3 to 6 months to prevent recurrence (rate of recurrence is 6 to 9%)
o Those with a history of idiopathic recurrent DVT, Factor V Leiden mutation, and cancer have poor prognosis and need to be on Coumadin indefinitely
Complications
- Bleeding (more of a problem than with heparin)
o 10 % of patients on Coumadin for 1 year have a bleeding complication - 1 % have a fatal hemorrhage (need to keep INR
Contraindications of coumadin
o History of PUD (peptic ulcer disease) or GI or GU bleeding
o Injuries or recent surgery to eyes, ears, CN
o Thrombotic stroke within previous 2 weeks
o Uncontrolled severe hypertension
o Platelet count
Surgery for DVT
Thrombectomy rarely done – Reserved for:
o Cannot be on anticoagulants, have extensive proximal thrombus (several cm)
Filters
o Placed at junction of femoral and external iliac, acts as a sieve
o May be used for people with recurrent DVT
Perioperative management
- Patients on long term anticoagulants (most commonly for a fib)
- **Always work with physician managing anticoagulants to see whether it is safe to temporarily D/C meds for surgery – consult on this
- Discontinue warfarin for 3 to 5 days before procedure to allow INR to return to normal and then restarting therapy shortly after surgery
Pulmonary embolism
- About half of patients with pelvic or proximal DVT will develop PE
- Risk of PE from calf or upper extremity vein, but much lower
o Veins are smaller, therefore clot is smaller - In a healthy individual, 60% of pulmonary vasculature must be occluded before signs of PE
- Etiology same as for DVT
PE effects on the heart
- Progressive right heart failure
Signs and symptoms of PE
- Sudden death in approximately 25%
- Dyspnea (shortness of breath) most frequent symptoms
- Tachypnea (increased respirations) most frequent sign
- ***Classic triad of dyspnea ,[most common symptom (73%)], hemoptysis (15%), pleuritic chest pain occurs (66%)
Differential diagnosis
- PE known as the “great masquerader”
- Presents similarly to Pneumonia, MI, Heart failure, Bronchitis, COPD, Pericarditis, Rib fracture or costochondritis, Asthma
Diagnostic studies for PE
KNOW THIS
- ***D-dimer
- ***ECG
- ***Chest x-ray
- ***V/Q scan (maybe)
- ***Spiral CT
D-dimer for PE
o Level >500 ng/mL present in 90% of patients with PE – typically elevated (like with DVT)
Chest x-ray for PE
***Chest x-ray is first imaging procedure that is obtained when patient presents with dyspnea
A normal or near normal x-ray in dyspneic patient highly suggestive of PE
Abnormalities indicative of PE
o Peripheral wedged shape density above the diaphragm
o Enlarged right pulmonary artery
V/Q Scan
If history, physical exam, and radiograph suggest PE, a ventilation/perfusion scan (V/Q scan) is ordered
o Normal = Ventilation and perfusion scan shows even distribution of tracer in both lungs
o High probability = At least one lobe or two or more segmental mismatches (ventilated, but not perfused) which is diagnostic for PE in 90% of cases, or
o Non-diagnostic = Majority of cases fit into this category
***Spiral CT (maybe)
o The table remains stationary while the CT ring rotates around the patient and the patient is continuously advanced through the slip-ring
o Done with contrast, good at detecting large thrombus but may miss smaller thrombi
Treatment of PE
We wont’ be treating this
Primary therapy
o Thrombolytics
o Pulmonary embolectomy
Secondary therapy
o Anticoagulation (Heparin, LMWH, Coumadin)
o Vena cava filter
Duration of anticoagulation
o Usually recommend at least 6 months
o Recurrence rate high after stopping therapy
Adjunctive therapy
o Pain medication, O2, Dobutamine to treat right heart failure
o Careful use of IV fluids – Don’t want to volume overload
Case study
- HPI - 58 year old female, slipped on ice, Left ankle pain and edema
- PMH - Hypothyroidism, osteopenia, hyperlipidema, HTN
- PSH - ORIF right arm, with later removal of symptomatic hardware
- FH - Osteoporosis with difficulty of fx healing
- Meds - Vicodin, simvasatin,levoxyl, estrogen and progesterone compounds, vit D, ASA, magnesium, Ca+, CoQ10
- SH - Smokes ½ pack/day, Denies alcohol, or illicit drug use, Works as a secretary, Very active and rides motorcycle recreationally
- ROS - Edema left ankle, none on right, Right shoulder and hand pain after fall
- Physical exam
o NVSI, Edema and ecchymosis to left foot and ankle, Pain with palpation of fibula
o Xrays (Non displaced left oblique fibula fx) - Assessment - Left fibula fx
- Plan - Discussed surgical vs surgical options, Patient wanted to start conservatively
o Short leg cast and strict nonweightbearing
o Risk factors for DVT? What do you want to do? - Result
o Went home, had severe SOB and chest pain, Went to ED and dx with massive PE, how can this be worked up?
Case study conclusion
Incidence of DVT and PE may be higher than once thought in foot and ankle surgery????
MUST HAVE LOW LEVEL OF SUSPICION
Keep DVT and PE in the back of your mind if patient comes in with
o Increased calf pain
o Red, edematous extremity
o Shortness of breath and chest pain
Document, Document, Document
