Initial Management of Pulmonary Embolism

Risk Stratification and Hemodynamic Assessment

The American Thoracic Society defines high-risk (massive) PE by hemodynamic instability, including systolic blood pressure <90 mmHg, shock, or cardiac arrest with collapse, unexplained hypoxia, engorged neck veins, and often right ventricular gallop 1, 2, 3
The European Society of Cardiology recommends that non-high-risk PE includes hemodynamically stable patients (systolic BP ≥90 mmHg without vasopressor support) 3, 4

The American College of Chest Physicians recommends starting anticoagulation with low molecular weight heparin (LMWH) at weight-based dosing (enoxaparin 1 mg/kg subcutaneously twice daily or 1.5 mg/kg once daily) for hemodynamically stable patients 3, 4
The European Heart Journal suggests that unfractionated heparin should be considered in specific scenarios, including massive PE with hemodynamic instability, high bleeding risk, severe renal dysfunction, or extreme obesity 5, 3

The American Heart Association recommends administering 50 mg alteplase IV bolus immediately for patients in cardiac arrest or with severe hemodynamic compromise 1, 2
The European Society of Cardiology suggests that thrombolysis should be undertaken in high-risk PE unless absolute contraindications exist 4

The Fleischner Society recommends that CTPA is the preferred initial imaging modality for non-massive PE 5, 3

The American College of Cardiology recommends starting warfarin only after VTE is confirmed on imaging, with an initial dose of 5-10 mg daily for 2 days, then adjusting to a target INR of 2.0-3.0 5, 3, 6

The Society of Critical Care Medicine recommends continuous ECG and oxygen saturation monitoring during initial stabilization, as well as oxygen supplementation to correct hypoxemia 3

The European Respiratory Society suggests that outpatient management may be considered for carefully selected stable patients if they are not unduly breathless, have no medical or social contraindications, and an efficient outpatient protocol is in place 5, 3

The American Thoracic Society recommends avoiding delays in anticoagulation while awaiting diagnostic confirmation in high-probability patients, and not withholding anticoagulation while awaiting imaging in patients with intermediate or high clinical probability 7, 5

The British Thoracic Society recommends starting anticoagulation as soon as pulmonary embolism (PE) is suspected with intermediate or high clinical probability, without waiting for diagnostic confirmation, as the risk of delayed treatment outweighs the risk of unnecessary anticoagulation in patients with reasonable clinical suspicion 8, 9

Before initiating anticoagulation, it is essential to assess clinical probability using validated criteria, as recommended by the British Thoracic Society 8
In the absence of all three findings—tachypnea, pleuritic pain, and arterial hypoxemia—PE can be excluded and anticoagulation withheld, according to the British Thoracic Society guidelines 9

The British Thoracic Society guidelines establish low molecular weight heparin (LMWH) as the standard of care for non-massive PE, having equal efficacy and safety to unfractionated heparin (UFH) while being easier to use 8
LMWH compares favorably with UFH in efficacy, unwanted effects, and allows for outpatient management, as demonstrated in multiple trials 10

Absolute contraindications to heparin include recent hemorrhage, acute stroke, and current gastrointestinal bleeding, as stated by the British Thoracic Society 11
Relative contraindications to heparin include peptic ulcer disease, surgery within 7 days, and prolonged cardiopulmonary resuscitation, according to the British Thoracic Society guidelines 11