Define Virchow's triad:
Classic triad for the pathogenisis of venous thrombosis: 1.) endothelial injury - surgical trauma or indirectly by hematoma formation, thermal injury from electrocautery or cement polymerization 2.) Alteration in blood flow: arterial turbulence or venous stasis (operating table/ post op secondary to immobilization or impaired ambulation) 3.) hypercoagulability (normal reponse to surgery)
List states that are associated with hypercoagulability:
genetic: antithrombin C deficiency, protein C deficiency, protein S deficiency, factor V leiden deficiency Aquired: post-op, post partum, prolonged bed rest or immobilization, severe trauma, cancer, oral contraceptives, malignancy, congestive heart failure, advanced age, nephrotic syndrome, obesity, prior thromboembolism
How common are genetic factors in association with hypercoagubility?
20-30% of patients with DVT have a predisposing factor
Where do venous thrombi occur?
mostly in the lower extremities in the superficial or deep veins
When do venous thrmobi develop?
DVT may begin during the surgical procedure, may present 24-48 hrs post surgically, late post op risk of DVT can continue up to 3 months
Incidence of DVT with total joint arthroplasty?
If no prophylaxis is used DVT occurs in 40-80% of patients and a proximal DVT occurs in 15-50% of these patients. Utilizing thromboembolic prophylaxis, early mobilization, and modern surgical technique reduced the incidence of fatal pulmonary embolism to
Does the type of anesthetic used during surgery affect the incidence of DVT?
Regional epidural anesthesia has been associated with a reduction in overall DVT (around 40-50% reduction) Hypotensive anesthesia may also be beneficial.
List the clinical signs and symptoms of a DVT?
calf pain, swelling, calf cramping, warmth, erythema, pain along the course of a vein, engorged veins, edema, low grade fever, palpable cord along the course of the involved vein
Is DVT easily clinically Dx'ed?
No, difficult with physical examination alone. Most are clinically silent.
What is Homan's sign?
Homan's sign is calf pain with forced passive foot DF; may be suggestive of DVT
Differential Dx for DVT?
muscle strain, cellulitis, superficial thrombophlebitis, chronic venous insufficiency, nerve compression syndromes, lymphedema, arterial occlusion, baker's cyst
most dreaded complication of DVT?
Signs and symptoms of a pulmonary embolism (PE)
Signs are nonspecific: pleuritic chest pain and dyspnea, cough, diaphoresis, apprehension, altered mental status, hemoptysis, tachypnea, tachycardia (most common), rales, fever bulging neck veins (30% of patient), pleural friction rub. A massive PE can result in syncope or sudden death. 2/3 of fatal PEs die within 30 min of symptoms.
Long term complications of PE?
chronic venous insufficiency secondary to venous dilation and valvular incompetence is a typical long-term DVT complication. At 5 yrs: night pain, pigmentation changes, pain with prolonged standing, venous ulceration, and edema can occur
Modalities to prevent formation of DVT:
Heparin: subcutaneously administered perioperatively, low molecular weight heparin post operatively, warafin, aspirin, fondaparinux, dextran (potential for heart failure and renal issues), mechanical - external pneumatic compression devices and compression stockings
What actions should a therapist take if a DVT is suspected to be present:
Hold off on interventions and inform the physician, keep affected limb NWB, diagnostic test may be ordered (by physician normally) and bed rest may also be prescribed
Discuss the sensitivity and specificity of diagnostic tests for DVT:
Ultrasound for asymptomatic patients 89% sensitive and 100% specific, venography - gold standard but is expensive and potential morbidityI fibrinogen scanning, MRI, D-dimer,
DVT confirmed, what Tx is available?
heparin, warfarin, foundaparinux, low molecular wt heparin
Mech of heparin and warfarin?
binds antithrombin III, increases inhibitory effect
PPT: partial thromboplastin time - used to monitor anticoagulation while on heparin
Define: PT (prothrombine time)
monitor anticoagulation while on warafin
Define INR (international normalized ratio)
represents measured PT adjusted by reference thromboplastin, kept between 2-3 for treatment or prevention of DVT