Instrument for Studying the Oxygen Transport in Capillaries
Keywords:
oximetry, capillaroscopy, capillary oximetry, spatially resolved oximetryAbstract
A possibility has been studied of the process of oxygen transfer to the tissues through the capillaries. The idea of spatially resolved oxymetry to be applied at the microscopic scale was induced due to appalling results of oxygen deficiency problems aroused as a result of the last pandemic of covid-19. A narrow window into the world of capillaries in the human body is the nailfold region which is used for the so-called nailfold capillaroscopy, a practical method for identifying and obtaining morphological description of capillaries, unveiling a bit of information on the health of microcirculation and potential pathological changes. The information assessed in capillaroscopy is based on the analysis of structural details of the capillary images. We decided to check this very narrow window of nailfold for in-vivo studies of a feasibility to get the argumentation for diagnosis and even for the prognosis of the disease.
The instrument, we designed, allows the unveiling of the functional activity of capillaries, the observation of how effi ciently they upload the oxygen to the tissues. We developed several versions of the prototype. The basic part of the instrument is the measuring microscope of the Mir-2 type with the 10× objective. The Hayear digital video camera is mounted on the top of the barrel instead of the eyepiece. In one of the versions, to avoid the reflexes from the oil drops on the nailfold, the tip of the finger is illuminated by light emitting diodes from the bottom of the finger bed. We tested also the light emitting diodes installed in the side walls of the finger holder.
The image of the capillaries is displayed on the 28-inch monitor. The image is registered with the HD resolution on the SD card installed in the video camera. The procedure is controlled by the program upon pushing the “Register” button. Not to touch the camera and not to shift the image accidentally during this procedure, that takes 200 ms, a remote control is used being included in the program loop. Registered images are then transferred to the computer for further processing. In this version of the instrument, we “decolorize” the images and pixel-by-pixel compare their intensities.
A prototype of the device has been designed and manufactured. Proposed and designed is the illumination schematic. The instrument structure is described including its parts, as well as the idea of image processing, the latter being acquired in different sections of the spectrum. In the studies, the narrow-band illumination was used in the regions of spectral lines 527 nm, 585 nm, and 650 nm, that were selected by the interference filters with transmission bandwidths 10-12 nm. As a conclusion, we found the narrow nailfold window into the world of capillaries still open, and hope our findings to be useful to further studies and tests with clinicians.
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