TOPIC41: pulmonary embolism

Question 1

what is PE?

Answer 1

-Occlusion of one or more arteries by a thrombi that originated elsewhere, typically in the deep veins on the lower extremities/pelvis

Question 2

Etiology of PE

Answer 2

1. DVT (95%)
   - Prolonged bed rest, surgery, severe trauma(burns, fractures), congestive HF, oral contraceptives( high estrogen) or hypercoaguable state
2. upper extremity veins (Central venous catheters)
3. Right sided heart chamber dilation.

Question 3

Risk for PE

Answer 3

1. Venous stasis: immobility, surgery, planes, obstruction, CHF
2. Vein damage: local trauma, previous thrombosis/phlebitis
3. hypercoaguable state

Question 4

heart and lung signs of PE

Answer 4

after the thrombus blockage:
A.lungs:
1. increased pulmonary artery pressure (and resistance)
2.atelectasis
3.decreased surfactant
4.reflex tachypnea
5.hypoxemia

B. heart:

1. diminished CO because the blood cannot flow to the left ventricle
2. blood will back behind causing cor pulmonale

Question 5

Signs and symptoms of PE

Answer 5

SMALL EMBOLI: automatically lysed–> no symp.

LARGER: Dyspnea, chest pain, cough, hemoptysis, altered mental status

MASSIVE: hypotension,reflex tachycardia, cyanosis, syncope, cardiac arrest

if VRF: Distended IJV with or without tricuspid regurgitation

DVT: leg edema, tenderness, erythema, pain on flexing ankle

Question 6

Clinical picture in PE (types according to severity)

Answer 6

1. acute massive
2. subacute: recurrent emboli
3. acute minor: dyspnea, pleuritic pain, hemoptysis, fever
4. chronis: PHTN, chronic cor pulmonale

Question 7

Diagnosis of PE (2 EXCLUSION, 6 SPECIFIC)

Answer 7

A.general for exclusion:

1. MI:
   - ECG–>tachycardia, S1Q3, right heart strain (repolarisation abnormalities due to hypertrophy or dilation)
2. aortic dissection:
   - CXR:normal or effusion, atelectasis, opacity if infarction
   - ABG: decreased pO2, pCO2–> hypoxemia and hypoventillation

B.Specific:

1. CT pulm angio
2. ventillation/ perfusion lung scan–> detect areas that are ventillated but not perfused
3. D-dimer: increased (indicates fibrinolysis)
4. lower extremity US
5. Troponin is increased if there is right ventricular strain
6. BNP: decreased indicates better prognosis than increased (measure level of HF)

Question 8

Therapy for PE

Answer 8

1. Initially:
   - supply oxygen
   - IV saline (hypotension)
   - vasopressors (stop tacchy)
   - anticoagulation (stop further coag)
   - morphine (stop pain)

2.Consider clot elimination:
a. Embolectomy
b. thrombolytic therapy (with tPA, streptokinase, urokinase eg streptokinase infusion for 24hr + hydrocortisone for side effects)
Heparin should always be added

3. Anticoagulation:
   - heparin IV 5000units bolus + 1000-2000 units/hr continuous infusion or LMWH subcutaneously (high dose)
   - Warfarin for long term 3 weeks to 6 months

Question 9

Prophylaxis for PE

Answer 9

• compression stockings
• LMWH
• avoid contraceptive pills if at risk
• vena cava filters of limited use