DEVELOPMENT OF A COMPUTER-AIDED THERMOELECTRIC PELTIER DEVICE FOR LOCAL COLD PROVOCATION TESTS WITH AN INTEGRATED PHOTOPLETHYSMOGRAPHIC SENSOR FOR THE NONINVASIVE EVALUATION OF ACRAL SKIN PERFUSION

Local cold provocation tests are an important, non-invasive diagnostic tool for collecting information about skin perfusion during exposure to cold. In patients suffering from vasospastic circulatory disorders such as Raynaud's phenomenon, it is of particular importance to be abl e to collect data about acral circulation during the cooling test in t he asymptomatic intervals between naturally occurring attacks. By carr ying out a series of cold provocation tests, for example, patient resp onse to a newly initiated therapy can be assessed. Here we present a r ecently developed, computer-aided thermoelectric Peltier device with a n integrated finger holder for carrying out local cold provocation tes ts. The electronic control unit of the Peltier element make it possibl e to cool or heat to predefined temperatures. At the same time, the te mperature of both the finger holder and the skin can be measured. A ph otoplethysmographic sensor is also integrated within the device, enabl ing the response of the pulse waves to the controlled temperature chan ges to be monitored accurately. It is also possible to measure simulta neously laser Doppler flux and capillary pressure in the nailfold and to perform nailfold capillaroscopy to-determine red blood cell velocit y. The new device provides us with the technical means to study the in terrelationship between acral skin perfusion and the thermal regulatio n of the skin.