Immediate Management of Suspected Pulmonary Embolism

Start anticoagulation immediately while diagnostic workup proceeds, unless the patient is actively bleeding or has absolute contraindications. 1

Initial Stabilization and Risk Assessment

Assess hemodynamic stability first – this determines your entire management pathway and mortality risk. 1, 2

If hemodynamically unstable (systolic BP <90 mmHg): Perform bedside echocardiography immediately to differentiate high-risk PE from other acute conditions like cardiac tamponade or acute MI. 1, 2
If stable: Proceed with structured diagnostic algorithm using clinical probability assessment. 1

For intermediate or high clinical probability PE, initiate heparin before imaging is completed. 1

Low molecular weight heparin (LMWH) is preferred over unfractionated heparin for stable patients – equal efficacy and safety with easier administration. 1
Unfractionated heparin should be used in massive PE, when rapid reversal may be needed, or as first-dose bolus in unstable patients. 1
Heparin is FDA-approved for prophylaxis and treatment of venous thrombosis and pulmonary embolism. 3

Use validated scoring systems (Wells' criteria or Revised Geneva score) or structured clinical gestalt. 1, 4
Do NOT order D-dimer in high clinical probability patients – proceed directly to imaging. 1

D-dimer <500 ng/mL excludes PE in low or intermediate probability patients (post-test probability <1.85%). 4
Age-adjusted thresholds can be used in patients ≥50 years to reduce unnecessary imaging. 1
Each hospital should provide sensitivity/specificity data for their specific D-dimer assay. 1

CT pulmonary angiography (CTPA) is the recommended initial imaging modality. 1

Timing: Within 1 hour for massive PE, ideally within 24 hours for non-massive PE. 1
A good quality negative CTPA reliably excludes PE – no further investigation needed. 1
V/Q scanning may be considered only if: chest X-ray is normal, no significant cardiopulmonary disease, facilities available on-site, and standardized reporting used. 1

Not diagnostic for PE but helps exclude other causes (MI, pericarditis). 1
May show signs of right heart strain in massive PE but lacks sensitivity/specificity.

Non-specific finding; hypoxemia can occur but is neither sensitive nor specific for PE. 1
Does not change management or diagnostic approach.

Obtain CXR to exclude alternative diagnoses (pneumothorax, pneumonia, heart failure). 1
Required if considering V/Q scan (must be normal). 1
May show Hampton's hump or Westermark sign but these are rare and non-specific. 5

Never delay anticoagulation waiting for imaging in intermediate/high probability patients – PE mortality is 7% within 1 week even with treatment. 1
Do not transfer unstable patients for additional imaging – treat based on clinical grounds if cardiac arrest is imminent. 2, 5
Beware of subsegmental PE on CTPA – discuss with radiologist as false-positives occur; avoid unnecessary anticoagulation. 1
Always consider alternative diagnoses – 16.7% of negative CTPAs show no abnormality, but most reveal other pathology (consolidation, effusion, emphysema). 6

If systolic BP <90 mmHg with RV dysfunction: Thrombolysis is first-line treatment. 1, 2

Alteplase 100 mg IV over 2 hours via peripheral vein (FDA-approved regimen). 2
If cardiac arrest imminent: Give 50 mg alteplase IV bolus immediately. 1, 2, 5
Withhold heparin during alteplase infusion; resume UFH 3 hours after completion. 2
In life-threatening PE, most contraindications to thrombolysis should be ignored given high mortality without treatment. 2, 5