DVT Flashcards
Where do arterial thrombi typically occur and initiated
In areas of rapid blood flow, often initiated by spontaneous or mechanical rupture of atherosclerotic plaques.
What are the main components of venous thrombi?
Fibrin and erythrocytes (red blood cells).
Where are venous thrombi most commonly found and what ‘re provocations for VTE
found primarily in the venous circulation
provoked by: Prolonged immobility and vascular injury.
In what type of patients is VTE most frequently seen?
Patients hospitalized for serious illness, trauma, or major surgery.
What are the possible outcomes of a formed venous thrombus?
- Remain asymptomatic (cause no symptoms)
- Spontaneously lyse (dissolve)
- Obstruct the venous circulation
- Circulate to other veins and embolize (break off and travel)
- Slowly incorporate into the vessel wall
VTE Impact & avoiding treatment
VTE can be debilitating or fatal, avoid treatment if diagnosis is not confirmed because treatment may cause major bleeding which might be equally harmful
DVT Presentation
Unilateral leg swelling (often starting after sleep), warmth, local tenderness/pain, and skin cyanosis.
What percentage of DVT patients are asymptomatic?
Over 50%.
What are the common symptoms of PE?
Nonspecific symptoms like dyspnea, pleuritic chest pain, anxiety, cough, and sometimes hemoptysis.
DVT precede PE inc80% or more of cases.
Clinical probability of PE:
low
moderate
high
low: 0-1
moderate: 2-6
high: 7 or more thn 7
D-dimer Test in DVT Diagnosis
- Used to rule out DVT in low clinical probability cases
- Quantitative measure of fibrin breakdown in serum
- Indicates acute thrombotic activity
- Sensitive but not specific for VTE
Contrast Venography in DVT Diagnosis
If the D-dimer test is positive , Contrast venography allows visualization of the entire venous system in the lower extremities.
* Venography is the most accurate and reliable method for diagnosis of DVT
* Venography is an expensive, invasive procedure that is technically difficult to perform and evaluate.
* Severely ill patients may be unable to tolerate the venography, and many develop hypotension and cardiac arrhythmias
* The contrast media used is irritating to vessel walls and toxic to the kidneys
What’s the preferred non-invasive DVT diagnosis method?
Duplex ultrasonography.
What imaging methods are used for PE diagnosis?
CT, MRI, and Ventilation/Perfusion scans
VTE risk factors according to Virchow triad
- Stasis in blood flow (circulatory stasis)
- Vascular endothelial injury
- Inherited or acquired changes in blood constituents causing hypercoagulation states(hypercoagulability)
Other risk factors for vte
Age: Risk doubles with each decade after age 50
History of VTE: Strongest known risk factor for DVT & PE
Drug therapy
* Estrogen-containing oral contraceptive pills
* HRT / ERT
* Chemotherapy
Fatality in VTE
DVT: Rarely fatal
PE: Death can occur within minutes of symptom onset
Complications of VTE?
- Post-thrombotic syndrome (PTS)
- Chronic thromboembolic pulmonary hypertension (CTPH)
PTS: a problem that can develop in nearly half of all patients after DVT.
PTS symptoms include chronic leg pain, swelling, redness, and ulcers
non pharmacological treatment of dvt
1- abmulation
2- GCS (graduated compression stocking)
3-(IPC) intermittent pneumatic compression
4- inferior vena cava filters
5-thrombectomy
abmulation and its adv
it is walking as soon after surgery
to increase the blood blow - decrease the incidence of vte
promote flow of natural thromobolytic factors into lower extremes
GCS adv and disadv
gcs is graduated compression stocking is socks that cause pressure help prevent thrombosis.
- in low moderate patients when pharmacological is contraindicated
- addictive effect when combine with pham
- uncomfortable to some patient, sue to leg shape n size, and hot
ipc adv and dis
intermittent pnematic compression
increase velocity of blood flow to lower extremes.
its used in surgical patient to prevent vte, it inflate and deflate in 1-2 min cylce
might be hot, uncomfortable, expensive, difficult sleeping
Inferior Vena Cava (IVC) filters
Greenfield filters,
short-term protection against PE in high risk patients
long term use cause thrombogenic themselves and increase the long-term risk of recurrent DVT
last choice
thromboctomy
surgically or mechanically
be considered in patients with massive iliofemoral DVT when there is a risk of limb gangrene due to venous occlusion.
Anticoagulant Drugs for vte
- Unfractionated heparin (UFH)
- Low molecular weight heparins (LMWHs) like dalteparin, enoxaparin
- Fondaparinux
- Warfarin
orthopadic surgey drugs
low dose ufh and warfin used in orthopedic surgery patient
fondaparinux is more effective than LMWH in orthopedic patient but has high risk of bleeding
aspririn modest reduction in vte after othopedic
thrombolytic uses and only used in?
- restore venous patency more quickly
- reserved for patients who present with shock, hypotension, or massive DVT with limb gangrene
FDA-approved thrombolytics for VTE: streptokinase, alteplase & urokinase
- reserved for patients who present with shock, hypotension, or massive DVT with limb gangrene
UFH should not be used during thrombolytic therapy.
UFH use
will not dissolve a formed clot but prevent its propagation and growth
UFH monitoring
appt baseline, 6 hour after infusion and 6 hours after each dose change. cuz css
therapeutic appt should be achived in 24 hours after initiating ufh
hb, hematocrit, platelet and bp shuld be monitro
bleeding risk 1-5% should be monitored sign and symptoms
bleeding and SE of UFH
if bleeding occur stop ufh, treat source of bleeding and give protamine sulphate
se: thrombocytopenia: top the drug & use another anticoagulant (not LMWH)
long term use of ufh and cautions
lonterm use >1mnth cause increased bone loss
pregnancy cat C
safe in breast feeding women
caution in peripartum period due to risk of maternal hemorrhage.
LMWH vs. Heparin Differences
- molecular weight, SE, monitoring, pk
- unlike heparin, lmwh have SC bioavailability: predictable dose response and longer pharmacodynamic effect.
- routine monitoring of appt doesnt require
- less side-effect compared to UFH
- bleeding risk less ( less than 3%)
- Heparin-induced thrombocytopenia less than ufh but still platlet monitoring needed 1st days
- do not cross placenta and is safe in preg
LMWH Dosage Determination
patient’s weight
(1.5mg/kg) or twice daily (1mg/kg).
bleeding risk high: 1.5mg/kg
bleeding risk low: 1 mg twice
Monitoring with LMWH
antifactor Xa activity measurement in specific situations
* Morbidly obese patients (weight greater than 150 kg)
* Patients <50 kg
* Significant renal impairment
* Children and pregnant women
