Diagnosing And Treating Pulmonary Embolism

Pulmonary Embolism:
Pulmonary Embolism (PE) is when a blood clot becomes lodged in an artery in
the lungs, obstructing blood flow and impairing oxygen exchange.
A pulmonary embolus refers to the blockage of the pulmonary artery or one of
its branches by material (e.g., thrombus, tumour, air, or fat) originating
elsewhere in the body. This disrupts blood flow and gas exchange in the lungs.
Pulmonary embolism can be unilateral or bilateral.

Pulmonary Embolism is classified as follows:

1. Pattern of Presentation:

• Acute Pulmonary Embolism: Symptoms develop immediately after the
  obstruction of an artery.
• Subacute Pulmonary Embolism: After the initial event, the patient presents
  with symptoms days or weeks later.
• Chronic Pulmonary Embolism: Ongoing or persistent symptoms without
  resolution.

2. Presence or Absence of Hemodynamic Instability:

• Hemodynamically Unstable Pulmonary Embolism: Massive or high risk. It is
  defined as systemic hypotension <90 mmHg or a drop of <40 mmHg for at
  least 15 minutes (not caused by arrhythmia) or shock.
• Hemodynamically Stable Pulmonary Embolism: Submassive or intermediate
  risk.

3. Anatomic Location:

• Saddle: Lodged at the bifurcation of the pulmonary artery.
• Lobar: Affecting the lobar branches of the pulmonary artery.
• Segmental/Subsegmental: Affecting smaller branches.

4. Presence or Absence of Symptoms:

• Sinus tachycardia.
• Hemodynamic status.
• Physical signs such as shortness of breath

Diagnostics:
The most common finding is sinus tachycardia.

1. Perform an ECG and Chest X-ray:
   Chest X-rays are usually normal.
   ECG may show right heart strain with S1Q3T3 (though not always).
2. Simplified Wells Score:
   Based on the score, the evaluation is modified.

• If the score is <2 (Low Probability), perform the Pulmonary Embolism Rule-out Criteria (PERC). If PERC = 0: PE is ruled out. If PERC >1, get D-dimers.
• With a low score <2, performed D-Dimers.
• If D-dimers <500, exclude PE.
• If D-dimers >500, perform a CTPA or V/Q scan.
• If the Wells score is >6, proceed directly to CTPA or V/Q scan. If negative,
  exclude PE.
• If PE is confirmed, differentiate submassive/low-risk PE from massive PE
  using an echocardiogram.
• If no RV dilation or dysfunction, it is a low-risk PE.
• If RV dilation/dysfunction is present, it is submassive/massive PE.
• If low BP is present, it is massive PE; if normal BP, it is submassive PE.

Treatment:
Is the patient hemodynamically unstable?

• No: Administer anticoagulation. If contraindicated, use an IVC filter.
• Yes: Administer TPA (tissue plasminogen activator). If contraindicated,
  perform an embolectomy.

Follow-up:

1. Prevention of PE:

• Pharmacological: LMWH, subcutaneous heparin.
• Mechanical: Pneumatic compressions.

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