Regimen

Use clinical decision rules (Pretest Probability of Pulmonary Embolism) to determine pre-test prob. of PE. If high prob., start anti-
coagulation before imaging study. Determine
d-dimer from 1st drawn blood to minimize
false 1.

Hemodynamically stable

Heparin 80U/kg IV bolus, then 18U/kg/h IV; or enoxaparin 1 mg/kg SC Q 12h or 1.5 mg/kg
SC QD; or tinzaparin 175 U/kg SC QD; or dalteparin 200U/kg SC QD or 100U/kg SC Q 12h). Consider thrombolytics (below) if echo shows RV dysfunction.

Massive with hemodynamic instability/persistent
hypoxia

Alteplase 10 mg IV bolus, then 90 mg IV over 2h;
or reteplase 10U IV over 2 min, repeat dose in 30 min; or streptokinase 250,000U IV over 30 min, then infusion of 100,000U/h for 24h; or urokinase 4400U/kg IV over 10 min, then infusion of 4400U/kg/h for 12h. Risk of intracranial
hemorrhage ~1-2%. Hold anticoagulation
during thrombolytic treatment; at completion, check PTT, start UFH or LMWH once PTT < 2.5x control.