DVT

Question 1

Define Virchow’s triad:

Answer 1

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)

Question 2

List states that are associated with hypercoagulability:

Answer 2

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

Question 3

How common are genetic factors in association with hypercoagubility?

Answer 3

20-30% of patients with DVT have a predisposing factor

Question 4

Where do venous thrombi occur?

Answer 4

mostly in the lower extremities in the superficial or deep veins

Question 5

When do venous thrmobi develop?

Answer 5

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

Question 6

Incidence of DVT with total joint arthroplasty?

Answer 6

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

Question 7

Does the type of anesthetic used during surgery affect the incidence of DVT?

Answer 7

Regional epidural anesthesia has been associated with a reduction in overall DVT (around 40-50% reduction) Hypotensive anesthesia may also be beneficial.

Question 8

List the clinical signs and symptoms of a DVT?

Answer 8

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

Question 9

Is DVT easily clinically Dx’ed?

Answer 9

No, difficult with physical examination alone. Most are clinically silent.

Question 10

What is Homan’s sign?

Answer 10

Homan’s sign is calf pain with forced passive foot DF; may be suggestive of DVT

Question 11

Differential Dx for DVT?

Answer 11

muscle strain, cellulitis, superficial thrombophlebitis, chronic venous insufficiency, nerve compression syndromes, lymphedema, arterial occlusion, baker’s cyst

Question 12

most dreaded complication of DVT?

Answer 12

pulmonary embolism

Question 13

Signs and symptoms of a pulmonary embolism (PE)

Answer 13

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.

Question 14

Long term complications of PE?

Answer 14

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

Question 15

Modalities to prevent formation of DVT:

Answer 15

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

Question 16

What actions should a therapist take if a DVT is suspected to be present:

Answer 16

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

Question 17

Discuss the sensitivity and specificity of diagnostic tests for DVT:

Answer 17

Ultrasound for asymptomatic patients 89% sensitive and 100% specific, venography - gold standard but is expensive and potential morbidityI fibrinogen scanning, MRI, D-dimer,

Question 18

DVT confirmed, what Tx is available?

Answer 18

heparin, warfarin, foundaparinux, low molecular wt heparin

Question 19

Mech of heparin and warfarin?

Answer 19

binds antithrombin III, increases inhibitory effect

Question 20

Define: PTT

Answer 20

PPT: partial thromboplastin time - used to monitor anticoagulation while on heparin

Question 21

Define: PT (prothrombine time)

Answer 21

monitor anticoagulation while on warafin

Question 22

Define INR (international normalized ratio)

Answer 22

represents measured PT adjusted by reference thromboplastin, kept between 2-3 for treatment or prevention of DVT