15: DVT and PE - Feilmeier Flashcards
define superficial vein thrombosis
Thrombus in superficial vein
Least serious
define thrombophlebitis
Presence of thrombus within a vein accompanied by inflammation
define thrombus
Clot composed initially of platelets and fibrin
RBC’s get interspersed in fibrin with time
sudden calf pain without other reason is …
DVT until proven otherwise
recurrent DVT rate
1/3 with DVT will have recurrence w/i 10 yrs
post phlebotic syndrome
1/2 long term complications post DVT
- edema
- pain
- induration
- pigment changes due to hemosiderin deposits
- ulceration
where does thrombus usually form?
at the valves
*** virchow’s triad
- HYPERCOAGULABILITY [ factor V leiden, antithrombin III, prtn C and S deficiency, tobacco use, pregnancy]
- STASIS [ microclots form around valves of veins]
- ENDOTHELIAL VASCULAR DAMAGE [exposes subendothelial collagen, promoting platelet aggregation]
review coagulation cascade
watch a youtube video
immobilization risk factors for DVT
- cast immobilization
- prolonged bed rest greater than 3 days
- acute MI
- CHF
- stroke
- long plane or car rides
vascular damage risk factors for DVT
- previous DVT
- trauma
- fx
- hip or knee replacement
- abdominal surgery
hypercoagulable state risk factors for DVT
- cancer
- pregnancy
- estrogen use
- 5-8% genetic risk
- factor V leiden (resistance to activated prtn C)
- antithrombin III, prtn C prtn S deficiency
review VTE risk sheet
found in onenote
pay attention to low, moderate, high risk and appropriate treatment/prophylaxis
Assign 1 risk factor for each of the following:
Operating room time >105 min
Tourniquet time >90 min
Rearfoot or ankle surgery
Assign 2 risk factors for each of the following:
Immobilization in a BK or AK cast for >1 wk
Medical or surgical patients confined to bed for >72 h
Central venous access
Assign 3 risk factors for each of the following:
Ankle/tibia/pilon fracture
Assign 5 risk factors for each of the following:
Multiple trauma
mechanical DVT prophylaxis
- bilateral penumatic sequential compression device (SCD)
- foot pumps
- graduated compression stockings (TED only good for non-ambulatory)
- early mobilization if possible
- active ROM of LE if possible
medical prophylaxis options
LMWH (lovenox/enoxaprin)
ASA
Xarelto/Rivaroxaban
Heparin
MOA LMWH (lovenox/enoxaprin)
factor Xa and II inhibitor
MOA xarelto/rivaroxaban
factor Xa inhibitor
s/s DVT
- symptoms peak at day 3-4 (again at 5-6 wks)
- most common complaint is calf pain
- leg swelling
- positive homan’s sign
- +/- distension of superficial collaterals
- +/- fever/tachycardia
- unilateral leg edema
- posterior calf tenderness and increased warmth
- erythema
- phelgmasia cerulea dolens, phelgmasia alba dolens
second DVT hit
6 wks
first day 3-4 aka ‘walk’
positive homans sign
pain in posterior calf with passive dorsiflexion
describe phlegmasia cerulea dolens and alba dolens
- blue hue due to stagnant deoxygenated blood
- pallor due to interstitial pressure exceeding capillary
palpable cords
more common with superficial thrombophlebitis
______ of thigh DVT will propagate to PE if left untreated.
_______ of calf DVT will propagate to thigh
- 50%
- 20-30%
+ D-Dimer =
+ when greater than 500 ng/ml
- D-dimer is a degradation product of cross-linked fibrin that is released into the blood during fibrinolysis
- Highly sensitive, has low specificity; + with increasing age, infection, inflammation
most common imaging diagnostic for DVT
duplex ultrasound
- 95% positive predictive value for proximal thrombosis
- 50-75% sensitivity in calf due to difficulty in v visualization
historical gold standard for DVT imaging
contrast venogram
Contrast medium injected into superficial vein in foot
- Directed to deep system by tourniquets
- Presence of filling defect
OR
- Absence of filling of deep veins diagnostic
what does gold standard mean?
procedure against which all other procedures are tested
ex: duplex ultrasound results are compared to the contrast venogram
If ultrasound is positive …
If ultrasound negative, but is at high risk*…
If venogram negative …
If moderate risk and the ultrasound is negative …
If ultrasound is positive
= Patient has DVT
If ultrasound negative, but is at high risk*
= Recheck in several days; Consider starting anticoagulation; Consider venogram
If venogram negative
= No DVT
If moderate risk and the ultrasound is negative
= Consider repeating scan in one week and withholding anticoagulation
physical measures DVT treatment
- warm moist heat to increase venous dilation
- adequate hydration
- analgesics
- elevation of extremity
- maybe in hospital watch
why use thrombolytics? what are thombolytics?
- Streptokinase
- Urokinse
- tPA
- Is not more effective in preventing PE but can: Accelerate clot lysis, Preserve venous valves, Decrease chance of developing postphlebitic syndrome
MOA unfractionated heparin
- Binds to antithrombin III which potentiates the inhibition of thrombin (II) and Xa, IXa, XIa, XIIa
- Inactivates thrombin by cofactor II which acts independently of ATIII
- intrinsic pathway
heparin prophylaxis dose
500 U SQ TID
treatment for DVT with heparin
IV bolus of 80 IU/kg
Then infuse at rate of 18 IU/kg/hour
- Titrate until aPTT is 1.5-2.3 times normal
- Monitor the anticoagulant response by using aPTT (activated partial thromboplastin time)
- Start Coumadin ~12-24 hours after induction of heparin therapy ***
- Heparin continued until INR (international normalized ratio) 2.0-3.0
how do you reverse heparin uncontrolled bleeding **
Reversed with protamine zinc sulfate (1mg/100 U of heparin)
Stop heparin immediately
describe thrombocytopenia HIT
- complication of heparin
- Can be accompanied by arterial or venous thrombosis
- Stop heparin immediately
- Consider alternative drugs such as Hirudin, Argatroban, or Danaparoid
- Check platelets after 5 days
how is LMWH different from heparin?
- increased bioavailability
- Prolonged half-life and predictable clearance
- Predictable antithrombic response permitting treatment without lab monitoring
- administered subQ bid/daily
- causes much less bleeding and virtually no thrombocytopenia
dosing lovenox/enoxaparin sodium
1 mg/kg sq q12 for DVT treatment
30 mg sq q12 hours for prophylaxis or 40 mg sq daily (started ~12 hours post-op)
when do you start coumadin?
- Start Coumadin 12-24 hours after starting LMWH until INR between 2 and 3 reached (same for heparin)
- Check platelets after 5 days due to chance of thrombocytopenia
reverse LMWH
- Reverse with protamine zinc sulfate (1mg for 1 mg of Lovenox)
- Bleeding returns to normal in approximately 12 hours
MOA coumadin/warfarin
Inhibits Vit K-dependent carboxylation of coagulation factors II, VII, IX, X, as well as, proteins C and S
coumadin paradox
Proteins C and S have shorter half life than coagulation factors
Get depleted faster leading to potential hypercoaguable state
describe coumadin “bridging”
Heparin/LMWH and Coumadin treatment should overlap by 4 to 5 days when Coumadin treatment initiated for DVT prophylaxis/tx
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
Extrinsic pathway
med interactions of coumadin
*P450 drug
Potentiate effects of
ASA, NSAID’s, Synthroid®, allopurinol, Bactrim
Decrease effects of
oral contraceptives, dicloxacillin, nafcillin
Raises the level of
oral hypoglycemics and anticonvulsants and Levaquin
coumadin dosing
Coumadin administered at initial dose of 5 mg/day for the first 2 days
Daily dose then adjusted according to INR - Usually want INR of 2-3
LMWH discontinued on 4th or 5th day following initiation of Coumadin therapy, provided INR in therapeutic range of 2 to 3
Once anticoagulant effect stable, INR should be monitored every 1 to 3 weeks
Most patients need to be on Coumadin for 3 to 6 months to prevent recurrence (rate of recurrence is 6 to 9%)
Those with a history of idiopathic recurrent DVT, Factor V Leiden mutation, and cancer have poor prognosis and need to be on Coumadin indefinitely
contraindications to anticoagulant therapy
History of PUD or GI or GU bleeding
Injuries or recent surgery to eyes, ears, CNS
Thrombotic stroke within previous 2 weeks
Uncontrolled severe hypertension
Platelet count
who gets thrombectomy?
- patients who can not be on anticoagulation therapy
- extensive proximal thrombus several cm long
who gets an IVC filter?
- Placed at junction of femoral and external iliac
- Acts as a sieve
- May be used for people with recurrent DVT
perioperative management warfarin
- Discontinue warfarin for 3 to 5 days before procedure to allow INR to return to normal and then restarting therapy shortly after surgery
- Treat patient with sub Q LMWH 12 hours before and after the surgical procedure, until Coumadin can be restarted
- Admit and start heparin upon d/c of coumadin
In a healthy individual, _____ of pulmonary vasculature must be occluded before signs of PE are evident
60%
PE effects on heart
Usual cause of death
May see right ventricular dysfunction on ECG
Poor prognosis if seen
As pulmonary resistance increases, right ventricular wall tension rises
Can lead to compression on coronary artery and subsequent MI
Interventricular wall bulges and places pressure on left ventricle
s/s 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%)
triad of PE
dyspnea
hemoptysis
pleuritic chest pain
diagnostic studies to order for PE
d-dimer ECG CXR V/Q scan spiral CT
CXR abnormalities indicative of PE
- peripheral wedged shape density above diaphragm
- enlarged right pulmonary artery
primary tx PE
thrombolytics
pulmonary embolectomy
