ABSTRACT
In most cases, a clinical concern about hypoxemia stems from a reading generated by a peripheral device, the pulse oximeter. Chest X-ray can indicate cardiac or pulmonary pathology and may be done at the bedside if the patient is unstable for transport or if oxygenation cannot be maintained despite supplemental oxygen. Cardiomegaly, hyperinflation, pulmonary edema, pneumothorax, pleural effusion, and pneumonia are all easy to diagnose on a chest X-ray. Treatment should be directed toward the most likely cause. If there is a clinical suspicion of pulmonary embolus, it is prudent to anticoagulate the patient while awaiting diagnostic testing. The cascade of testing will vary from institution to institution. Clinical suspicion plus abnormal lower extremity compression ultrasound studies are probably enough to assume pulmonary embolus, but negative lower extremity studies are insufficient to rule out pulmonary embolus: a V/Q scan or chest computed tomography (CT) scan will be required.
