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Laser Doppler Monitoring

Laser Doppler measures the total local microcirculatory blood perfusion including the perfusion in capillaries (nutritive flow), arterioles, venules and shunting vessels. The technique is based on the emission of a beam of laser light carried by a fiber-optic probe.

The light is scattered and partly absorbed by the tissue being studied. Light hitting moving blood cells undergoes a change in wavelength (Doppler shift) while light hitting static objects is unchanged. The magnitude and frequency distribution of these changes in wavelength are directly related to the number and velocity of the blood cells in the sample volume. The information is picked up by a returning fiber, converted into an electronic signal and analyzed.

The measuring depth depends on tissue properties such as the structure and density of the capillary beds, pigmentation, oxygenation, etc. It also depends on the wavelength of the laser light, and on the distance between the sending and receiving fibers in the laser Doppler probe.In normal skin, using Perimed laser Doppler instruments, a probe with standard fiber separation (0.25 mm), and a 780 nm wavelength laser, the measuring depth will be in the order of 0.5-1 millimeter. In blood-rich organs such as the kidney or the liver, the measuring depth is considerably less than one millimeter. When the blood supply to a region is occluded, the "apparent" measuring depth will increase since the lack of blood will permit more passage of light.

No current laser Doppler instrument can provide absolute perfusion values (e.g. ml/min/100 gram tissue). Measurements are expressed as Perfusion Units (PU), which are arbitrary. To enable comparison of results, it is absolutely essential to calibrate the laser Doppler. Perimed was the first company to develop a special Motility Standard for this purpose.

PeriFlux 5000 LDPM

The PeriFlux System 5000 is an adaptable instrument with capacity of up to 4function units af free combination. Choose between PF 5010 LDPM unit, PF 5020 Temp unit, PF 5040 tcpO2/tcpCO2 unit and PF 5050 Pressure unit.

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Improving quality of life since 1981

Perimed AB, established in 1981, provides instruments, software and expertise to enable assessment of the microcirculation. We utilize laser Doppler, laser speckle (LASCA) and transcutaneous oxygen (tcpO2 or TCOM), to accurately monitor and quantify blood perfusion and tissue oxygenation in real-time. Our modular PeriFlux System 5000 and PeriFlux 6000, the latest generation of our PeriFlux System, are excellent choices for diagnosing Peripheral Arterial Disease (PAD) and Critical Limb Ischemia (CLI) or for assessing wound healing potential in your vascular patients. Our blood perfusion imagers PeriScan PIM 3 System and PeriCam PSI System, allow you to investigate spatial distribution, for example during cortical spreading depression.