What is the major abnormality and what is its significance?
CXR: Oligaemia of left lung field - signifying less blood perfusing that lung. (Westermark's sign)
Trick: Stand back sometimes to see things clearer on xrays
Dx: Pulmonary embolus (affecting main left arterial trunk)
Rx: O2, fluids, heparin, CT to confirm, consider thrombolytics