Measurement Methods Overview

• Impedance Plethysmography (IPG) - noninvasive technique to measure the changes in blood volume of a segment. A low amount of high frequency alternating current is passed through sensors and the changes in electrical resistance (impedance) caused by the blood volume changes are measured. Using impedance plethysmography it is possible to measure changes in venous blood volume as well as the pulsations of the arteries.

  The rheoscreen® compact is based on impedance plethysmograhpy technology.

• Venous Occlusion Plethysmography (VOP) - a specific, and the most common, application of Impedance Plethysmography. Generally, a pressure cuff is used to temporarily close the veins. Then the rate at which the veins fill or empty is measured to diagnose blood flow disturbances or occlusions.

  The rheoscreen® compact excels at the VOP technique.

• Pulse wave analysis (also called Rheography) - is another application of Impedance Plethysmography. The shape and size of the arterial pulse changes with every disease. Therefore, the measurement and analysis of the arterial pulse wave is a simple and powerful diagnostic tool for any kind of arterial disease.

  The rheoscreen® compact has the latest technology to enable pulse wave analysis.

• Photo Plethysmography (PPG, also known as Light Reflection Rheography or LRR) - noninvasive technique where non-visible infrared light is emitted into the skin. Depending on the blood volume in the skin, more or less light is absorbed. By measuring the non-absorbed light, the changes in blood volume can be measured. As with impedance plethysmography the changes in venous volume (venous test) can be measured as well as the arterial pulse wave (photopulse).

  The rheoscreen® light uses a modern kind of photoplethysmography technology.

• Peripheral Venous Pressure (PVP, also known as phlebodynametry) - the direct measurement of the peripheral venous pressure and is, therefore, the best method to use to acheive an exact diagnoses. This is the gold-standard reference of techniques that all others are compared to. This method is minimally invasive, requiring only a needle inserted into a vein on the back of the foot.

  The rheoscreen phlebo device works with phlebodynametry.

• Vascular Doppler - is a standard method in vascular diagnostics for measuring the blood flow in selected vessels by ultrasound.

  The rheoscreen doppler utilizes this Doppler technology.

• Impedance Cardiography (ICG) - a noninvasive monitoring technique, which is especially known for the noninvasive measurement of cardiac output. Similar to IPG, ICG measures the impedance (resistance of an AC circuit) changes of the thorax caused from the pumping heart to monitor cardiac parameters. The common ECG shows the electrical activity of the heart. But with ICG you see "the heart beating".

  The cardioscreen pages describe the monitoring equipment in more detail.