Typical – Fever – cough with sputum – infiltrates on CXR Treatment – beta agonist – empiric antibiotics – steroids Clinical response Improvement Continue treatment D–dimer negative positive Creatinine > 1.5 <1.5 PE excluded Doppler US No improvement VTE confirmed treatment positive negative High or low clinical probability V/Q scan Moua and Wood Respiratory Decompensation in Patients with Established COPD Pre – test probability for PE Low Intermediate High PE excluded Low clinical probability– Low scan probability High clinical probability – High scan probability Figure 1 Respiratory decompensation in patients with established COPD. Abbreviations: COPD, chronic obstructive pulmonary disease; PE, pulmonary embolism;V/Q, ventilation/perfusion ratio. 282 International Journal of COPD 2008:3(2) Atypical – absence of fever – abrupt presentation – no cough or sputum change – clear CXR Intermediate clinical probability Negative–PE excluded Positive–PE confirmed Spiral CT High or low clinical probability – Intermediate scan probability PE confirmed – treatment