A new laser Doppler flowmeter prototype for depth dependent monitoring of skin microcirculation

Potential of Laser Doppler Flowmetry in the Medical Needle Insertion Procedures

Medical needle insertion procedures possess the risk of life-threatening blood vessel rapture. Here we report a compact laser Doppler Flowmetry (LDF) based system that has a potential of blood vessel detection in the vicinity of the moving needle. The developed LDF system comprises two optical fibers inserted into the needle (the probe), a laser unit and a photodetector. The latter collects the signal produced by photons, scattered from the moving red blood cells that is further converted into perfusion value. Using LDF system, we have been able to detect the flow independently from the needle penetration angle, site or depth. Moreover, we showed that the blood vessel can be identified inside the tissue phantom while the probe is moving. Our results demonstrate that the developed LDF system is flexible and compatible with different types of needles and thus has a potential in the needle insertion procedures.

Variability of microcirculation detected by blood pulsation imaging

The non-invasive assessment of blood flow is invaluable for the diagnostic and monitoring treatment of numerous vascular and neurological diseases. We developed a non-invasive and non-contact method of blood pulsation imaging capable of visualizing and monitoring of the two-dimensional distribution of two key parameters of peripheral blood flow: the blood pulsation amplitude and blood pulsation phase. The method is based on the photoplethysmographic imaging in the reflection mode. In contrast with previous imaging systems we use new algorithm for data processing which allows two dimensional mapping of blood pulsations in large object's areas after every cardiac cycle. In our study we carried out the occlusion test of the arm and found (i) the extensive variability of 2D-distribution of blood pulsation amplitude from one cardiac cycle to another, and (ii) existence of the adjacent spots to which the blood is asynchronously supplied. These observations show that the method can be used for studying of the multicomponent regulation of peripheral blood circulation. The proposed technique is technologically simple and cost-effective, which makes it applicable for monitoring the peripheral microcirculation in clinical settings for example, in diagnostics or testing the efficiency of new medicines.