Occlusive impedance phlebography. A test done with special equipment that uses external electrodes and an inflatable pressure cuff (wrapped around the thigh) to detect blood clots or a risk for developing blood clots in each leg. The test can also assess the possibility of such clots in the lungs. The graphs obtained from the blood volume-measuring machine (plethysmograph) are then interpreted to obtain the results of the test. A slow rise or drop may indicate a blocked vein.
A device that uses gas-to-tissue ratio to set an alarm or measure a volume.