The microcirculation
The microcirculation, i.e. the blood flow of the smallest vessels in the body, is an essential part of the circulation in the body. The larger vessels ensure that the blood can be transported from the heart to all parts of the body, but it is in the smallest vessels that oxygen and nutrients are released from the blood to the cells and waste products from the cells enters the blood. Since the microcirculation is close to all cells in the body, the need of oxygen and nutrients of each cell can be met. When the cells have an increased oxygen demand, a special type of cells in the vessel walls, endothelial cells, can release substances that create a dilatation of the vessel, which then increases blood flow in the vessel and thus also the amount of available oxygen to the cells in the particular area
Some diseases impair endothelial function
Several diseases, e.g. diabetes mellitus, hypertension and peripheral vascular disease are associated with an impaired microcirculation and endothelial function. This means, that in these diseases the blood flow in the microcirculation is affected, which may cause the cells to have a reduced amount of available oxygen. An impaired endothelial function is also known as a cardiovascular risk factor. Today there is knowledge that cardiovascular disease and diabetes lead to changes in the microcirculation. But changes in the microcirculation could also be the first sign of cardiovascular disease and diabetes.
Optical technique for microcirculatory measurement
At the Department of Biomedical Engineering at Linköping University, in collaboration with Perimed AB, we have developed a new biooptic system called EPOS, Enhanced Perfusion and Oxygen Saturation system, which quickly and easily measures skin microcirculation. By illuminating the skin with different types of light, it is possible to measure blood flow, the amount of blood and oxygen saturation in the microcirculation. The technique is based on diffuse reflectance spectroscopy and laser Doppler flowmetry measurements, where the characteristic way that hemoglobin absorbs light and the frequency change that occurs when light hits a moving blood cell are used. By using mathematical models and simulations of light scattering in the skin, microcirculation can be quantified in real time.
Relationship between microcirculation and cardiovascular disease
In our additional study to SCAPIS, SCAPIS micro, the aim is to explore the association between skin microcirculatory function and cardiovascular disease and diabetes. Microcirculatory function or endothelial function is assessed by blocking the blood flow in the forearm for a short period of time, creating an increased oxygen demand in the tissue which in turn leads to activation of the endothelial cells and an increased blood flow when the occlusion is released. In SCAPIS micro, the goal is to include about 4000 individuals of the total 5000 included in SCAPIS Linköping. By combining measurements of the smallest vessels with investigations of the large vessels, hearts and lungs of such a large group of individuals, we get a unique opportunity to study the relationship between impaired microcirculation and cardiovascular disease and diabetes, which has never been done in this way. In the long run, we hope to find new risk markers for cardiovascular disease and diabetes.
