Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
36 Cards in this Set
- Front
- Back
|
Where doss DVT originate?
|
Originate in deep calf veins
|
|
|
What is pulmonary thromboembolism?
|
Movement of a blood clot from a systemic vein through the right side of the heart to the pulmonary circulation
Lodges in one or more branches of the pulmonary artery |
|
|
What is the etiology of pulmonary thromboembolism?
|
90% of cases - lower extremities are source of thrombi that embolize to the lungs
10% source are: arms, pelvis, right-sided heart chamber |
|
|
What is Virchow's Triad?
|
Risk factors for VTE
1. Venous stasis 2. Hypercoagulability 3. Vessel wall damage |
|
|
What is the genetic predisposition for hypercoagulability?
|
Deficiency of protein with antithrombotic activity (Protein C, Protein S)
Abnormal variant in coagulation cascade (Factor V Leiden) |
|
|
What causes venous stasis?
|
Prolonged immobility
Hospitalization for serious medical illness Long-distance air travel Spinal cord injury/paralysis |
|
|
What causes vessel wall damage?
|
Lower extremity trauma/fractures
Lower extremity orthopedic surgery Central venous catheter placement |
|
|
What are other risk factors for VTE?
|
History of prior thromboembolism
Malignancy - procoagulant activity Obesity Pregnancy, oral contraceptives |
|
|
What are factors affecting lung injury?
|
Location of occluded pulmonary artery
Presence of other cardiopulmonary disorders |
|
|
What are pathologic consequences of VTE?
|
Rapid clot dissolution
Thrombus quickly lyses with smaller fragments moving distally into the pulmonary artery circulation Usually lung is uninjured due to sufficient oxygen supply from other sources |
|
|
What is pulmonary hemorrhage?
|
Tissue distal to the obstructed artery may demonstrate hemorrhage and edema
|
|
|
What is pulmonary infarct?
|
Necrosis of lung tissue occurs if minimal or no other oxygen supply reaches parenchyma
|
|
|
How are physiologic problems caused?
|
Mechanical obstruction of pulmonary artery
Release of various mediators from the thrombus itself |
|
|
How do you get dead space with a thrombus?
|
Perfusion of pulmonary capillaries ceases as a result of thrombus
If ventilation to corresponding alveoli continues then the ventilation is wasted = dead space |
|
|
How is pulmonary vascular resistance affected by VTE?
|
Pulmonary vascular bed normally capable of recruitment and distention of vessels
~50% of vascular bed must be occluded before resistance or pressure increases Release of chemical mediators also contributes to vasoconstriction |
|
|
How does heart failure occur with VTE?
|
Vascular bed is severely compromised, the pulmonary vascular resistance becomes so high that the right ventricle cannot cope with the acute increase in workload
|
|
|
What are secondary effects of VTE?
|
Release of histamine, serotonin, prostaglandins
Resulting bronchoconstriction |
|
|
What are symptoms of VTE?
|
May be asymptomatic
Shortness of breath Plueritic chest pain Hemoptysis Cough Syncope |
|
|
What is found on the physical exam of a patient with VTE?
|
Tachycardia
Tachypnea Rales on chest exam Cardiac exam - increased P2 Lower extremity swelling |
|
|
How is the arterial blood gas in VTE?
|
Respiratory alkalosis and hypoxemia
Occasionally PO2 is normal |
|
|
What is D-dimer?
|
Produced clot breakdown
Elevated in presence of clot Many causes for false-positive Negative D-dimer test appears to reliably exclude the diagnosis |
|
|
How is DVT most commonly detected?
|
Doppler ultrasound
Sensitive and specific |
|
|
What is seen on EKG for VTE?
|
Non-specific and insensitive
Most common: sinus tach, nonspecific changes Classic finding is S1Q3T3 |
|
|
What is Westermark's Sign?
|
Enlarged left hilum on CXR
Left lung hyperlucent from poor perfusion |
|
|
What is Hampton's Hump?
|
Infarction appears as opacified region on CXR
Density shaped like truncated cone |
|
|
What are the problems with ventilation-perfusion scans?
|
Actual emboli not visualized
May have false positive scan - decrease in blood flow may result from primary lung or airway disease Often not diagnostic |
|
|
T/F: Spiral CT scans are not very sensitive and specific.
|
False
Beneficial even if patient has other pulmonary disease |
|
|
What was previously known as the "gold standard" for diagnosing VTE?
|
Pulmonary angiogram
Negative angiogram > 90% certainty in exclusion of PE Increased risk in performing procedure |
|
|
What are the short and long term treatment goals?
|
Short - present formation of new thrombi, present propagation of old clots, lysis of clots in some cases
Long - prevent recurrent event |
|
|
What is initial anticoagulation therapy?
|
Heparin (LMWH) - start immediately
Continuation of therapy with coumadin (Vit K antagonist) for minimum of 3 months |
|
|
How does thrombolysis work?
|
Dissolves thrombi by activating plasminogen to plasmin
Plasmin degrades fibrin into soluble peptides Beneficial in massive PE; slightly higher risk of bleeding |
|
|
What is the function of an Inferior Vena Cava Filter?
|
Trap thrombi from lower extremities en route to pulmonary circulation
Useful if contraindication to anticoagulation Main complication - leg swelling |
|
|
What is obstructive sleep apnea?
|
5 or more obstructed breathing events per hour of sleep
Repetitive obstructions of the upper airway during sleep |
|
|
What are signs of obstructive sleep apnea?
|
Chronic, disruptive snoring
Witnessed apnea Gasping/choking during sleep Excessive daytime hypersomnolence Motor vehicle or work-related accidents Personality changes/cognitive defects Family history |
|
|
How is obstructive sleep apnea diagnosed?
|
Gold standard: formal polysomnography with full-time technical attendance
Nocturnal oximetry: sensitive, not specific (only useful if completely normal - excludes OSA) |
|
|
What is the mechanical therapy for obstructive sleep apnea?
|
Orthodontics
Nasal CPAP - first line treatment |
