SM 169 Pulmonary Embolism Flashcards
What is the classic presentation for Pulmonary Embolism?
There isn’t one; though typical symptoms can include pleuritic chest pain, hemoptysis, and dyspnea
Why is treating Pulmonary Embolism difficult?
It produces non-specific symptoms, has high morbidity and mortality if missed, but also lends itself towards over-testing and over-treatment
What are the 3 risk factors that fuel Pulmonary Embolism?
Venous stasis, alterations in coagulation, and vascular injury
How does venous stasis promote Pulmonary Embolism?
Immobility from lying in a bed, prolonged ravel, or paralysis can promote clot formation in the legs that dislodges and blocks the Pulmonary circulation
How do alterations in coagulation promote Pulmonary Embolism?
Hereditary thrombophilias (Factor V), estrogen therapy, and malignancy can predispose clot formation which can block the Pulmonary circulation
How does vascular injury promote Pulmonary Embolism?
Surgery, trauma, and childbirth can all injure the vasculature and promote the formation of clots that dislodge and block the Pulmonary circulation
How are the risk factors for Pulmonary Embolism “synergistic”?
The risk factors make eachother worse and increase the likelihood of Pulmonary Embolism
Where do most Pulmonary Embolism arise from?
Deep veins in a proximal lower extremity, such as the Femoral and Popliteal veins, which then break off and block the Pulmonary circulation
What is a Pulmonary Embolism from a deep vein called?
DVT, most common type
What predisposes upper extremity DVT’s?
The use of Peripherally Inserted Central Catheters (PICC’s)
Where are the possible areas for a Pulmonary Embolism to cut off circulation?
"Saddle" = at the intersection of the RPA and LPA "Segmental" = blocking a major Bronchi "Sub-segmental" = blocking a distal branch of Pulmonary Circulation
What type of Hypoxemia results from blocking a Pulmonary Artery?
Dead Space
What type of Hypoxemia results from a Pulmonary Embolism?
V/Q Mismatch
What does a sudden increase in dead space indicate in a patient?
Pulmonary Embolism, due to sudden loss of perfusion to an area of the lung
Does a Pulmonary Embolism result in hypercapnia or hypocapnia?
Pulmonary Embolism results in Hypocapnia, because the loss of blood flow triggers an increase in ventilation to maintain PaO2 leading to decreased PaCO2
Why does Pulmonary Embolism result in hypoxemia?
The blood that is cut off by the embolism is shunted to other areas that are not blocked, leading to an increase in flow that overwhelms regional ventilation, precipitating V/Q mismatch
How does Pulmonary Embolism lead to CV collapse?
A large Pulmonary Embolism increases afterload on the RV, leading to RV dilation and a shift of the IV Septum into the LV, compressing the LV and lowering LV Preload leading to lower Cardiac Output
How is hypotension in the setting of Pulmonary Embolism treated differently?
Normally, acute hypotension is treated by administering fluids; however, in Pulmonary Embolism induced RV failure, pushing fluids increases the strain on the RV by increasing it’s preload, leading to more dilation and worsening Cardiac Output
What sign indicates a Pulmonary Embolism on an echo of the heart?
The “D” sign - due to RV compression of LV
How does Pulmonary Embolism effect the RV?
Vicious cycle; Increased afterload leads to dilation, but dilation causes LV preload to drop and diminishes CO, leading to further dilation. Additionally, increased RV pressure leads to decreased coronary perfusion, in the setting of increased myocardial O2 demand
Why can Pulmonary Embolism rapidly decompensate?
Increased O2 demand by the heart is not met, and actually worsened, by the failing Cardiac Output due to RV dilation and decreased LV Preload
What’s the point of a CXR in a suspected Pulmonary Embolism if it can’t be seen?
CXR can be sued to identify alternative diagnoses and rule out other things, allowing diagnosis of Pulmonary Embolism by exclusion
What results from a CXR would raise suspicion for Pulmonary Embolism?
Normal CXR with respiratory symptom should raise concern for Pulmonary Embolism
Why is angiography no longer the gold standard for diagnosis of Pulmonary Embolism?
Angiography is invasive, requires contrast, specialist involvement, and cannot detect small clots