Study Notes on Pulmonary Embolism

Definition: A pulmonary embolism (PE) occurs when a blood clot (or other material) obstructs a blood vessel in the lungs.

Critical Thinking Question: Investigate why many patients are suspected to have a pulmonary embolism without an official diagnosis.

Figure 20-1: Visual representation of pulmonary embolism demonstrating:
- A) Bronchial smooth muscle constriction
- B) Atelectasis
- C) Alveolar consolidation
- D) Common secondary anatomical alterations of the lungs associated with PE.

Statistics: Over 600,000 annual cases of PE reported in the U.S.
- Resulting in approximately 60,000-100,000 deaths annually.
- Most pulmonary blood clots originate from deep venous thrombi (DVT).

Most Common Cause: Blood clots.
Other Possible Causes:
- Fat
- Air
- Bone marrow
- Tumor fragments.
Activity Questions:
- How often does PE result in sudden death?
- How many DVTs result in a PE?

A blood clot traveling from one part of the body to another is termed:
- A. Deep vein thrombosis (DVT)
- B. Aneurysm
- C. Thrombus
- D. Embolus
Most Common Cause of PE:
- A. Bone marrow
- B. Blood clot
- C. Amniotic fluid
- D. Air or oxygen bubbles.

Box 20-1: Risk factors include the following categories:
- Venous Stasis:
- Inactivity
- Prolonged bed rest (e.g., during pregnancy)
- Prolonged periods of sitting
- Orthopedic procedures (e.g., pelvic/hip/knee replacements)
- Patients lacking prophylaxis
- Presence of varicose veins.
- Hypercoagulation Disorders:
- Use of oral contraceptives
- Pregnancy and childbirth
- Supplemental estrogen, particularly in women over 30 years old
- Conditions such as polycythemia.
- Additional Factors:
- Obesity
- Family history of clotting disorders
- Smoking
- Burns.

Box 20-2: Signs and symptoms commonly associated with PE include:
- Sudden shortness of breath
- Tachycardia
- Weak pulse
- Lightheadedness or fainting
- Anxiety
- Excessive sweating
- Cyanosis
- Cool or clammy skin to the touch
- Chest pain resembling a heart attack
- Coughing up blood-streaked sputum (especially if lung infarction is present)
- Wheezing
- Leg swelling.

Common diagnostic methods:
- Chest X-Rays
- Computerized Tomography (CT) Scan
- Electrocardiogram (ECG)
- Ventilation/Perfusion Scan (V/Q scan)
- Pulmonary Angiogram.
Additional Tests for Detection of Blood Clots:
- D-dimer Blood Test: Detects protein fragments from dissolved blood clots. Normal range: 0.5 mg/L.
- Duplex Venous Ultrasonography.

Vital Signs in PE patients:
- Increased respiratory rate (tachypnea)
- Increased heart rate (tachycardia)
- Systemic hypotension (decreased blood pressure)
- Cyanosis, cough, hemoptysis
Auscultation Findings:
- Crackles
- Wheezes
- Pleural friction rub.
Peripheral Edema and Venous Distention:
- Distended neck veins
- Swollen and tender liver.
Other signs:
- Chest pain and decreased chest expansion
- Syncope, light-headedness, confusion.
Heart sounds may include:
- Increased second heart sound (S2) due to a more forceful closing of the pulmonic valve
- Right ventricular heave (lift) as a result of elevated pulmonary arterial pressure (PAP) or right ventricular hypertrophy.

Abnormal Patterns:
- Sinus tachycardia
- Atrial arrhythmias (e.g., atrial tachycardia, atrial flutter, atrial fibrillation).

Chest Radiograph may show:
- Increased density in infarcted areas
- Hyperradiolucency distal to the embolus
- Dilation of pulmonary arteries
- Pulmonary edema
- Right ventricular cardiomegaly (cor pulmonale)
- Pleural effusion (usually small).
V/Q Scan Interpretation:
- Normal: No perfusion deficit.
- Low Probability: Perfusion deficit with matched ventilation deficit (less than 20% chance of PE).
- Intermediate Probability: Perfusion deficit correlating with parenchymal abnormality on chest x-ray (20%-80% chance of PE).
- High Probability: Multiple segmental perfusion deficits with normal ventilation (more than 80% chance of PE).

Immediate Management:
- Fast-acting anticoagulants:
- Heparin:
  - High-molecular-weight heparin monitored by activated partial thromboplastin time (APTT): Normal range: 24-32 seconds
  - Low-molecular-weight heparins:
  - Enoxaparin
  - Dalteparin
  - Tinzaparin.
- Warfarin administered alongside heparin for 5-7 days:
- Generic names: Coumadin, Panwarfin, Eliquis.
- International Normalized Ratio (INR) values:
  - Normal range: 0.8-1.2)
  - Target range on Warfarin: 2.0-3.0 (less than 2 indicates a higher clotting risk, over 3 increases bleeding disorder risk).
- Prothrombin time normal:12-15 seconds.
Thrombolytic Agents:
- Streptokinase
- Urokinase
- Ateplase (tPA/Tissue plasminogen activator).

Protocol for initiating oxygen therapy: To treat hypoxemia and decrease the work of breathing (WOB) as well as myocardial workload.
Aerosolized Medication Protocol: To alleviate bronchial smooth muscle contraction in cases of wheezing.
Lung Expansion Therapy Protocol: For patients developing significant atelectasis.

The safest and most effective fast-acting anticoagulants include:
- A) Low-molecular-weight heparin
- B) High-molecular-weight heparin
- C) Warfarin
- D) Streptokinase.
General management of a pulmonary embolism includes all of the following methods EXCEPT:
- A) Tight-fitting elastic stockings
- B) Administering a fibrinolytic agent
- C) Bed rest
- D) Administering an anticoagulant agent.