The purpose of this study is to prove that bedside Ultrasound Compression is a useful screening tool for the diagnosis of occult deep vein thrombosis in patients presenting to the emergency room with hypoxia.

It is known that 30% of deep vein thrombosis of the extremities is belived to be the precedend of pulmonary emboli; an often fatal disease. It is known that DVT (deep vein thrombosis is often occult.

It is also known that pulmonary embolism is often difficult to diagnose and is often missed especialy in patients with chronic illnesses such as COPD and CHF.

Venous compression ultrsound is an exam that can be preformed bedside. It is preformed by placing a vascular ultrasound transducer on the femoral vein and popliteal and checking its compressibility. If DVT is present in the femoral or popliteal veins the veins will be noncompressible. It has been shown that US compression for DVT can be preformed by physicians in the ER with accuracy and speed.

Presently US compression is not a tool used for detection of occult DVT in the ER. I wish to explore the usefullness of compression US of the lower extremities as a screening tool for DVT In the hypoxic patient.

Inclusion Criteria:

• Patients presenting to the Emergency room
• 18 years or older, saturation 94% and under on room air.

Exclusion Criteria:

• none

patients with saturation under 94% room air