Haemorheology and the inflammatory process

Many forms of tissue injury, whether due to physical or infectious sources, lead to the inflammatory response. During its course a wide variety of events takes place, including alterations in vascular contraction, in vascular permeability, in leucocyte activity and the initiation of the acute phase response. The last results in a leucocytosis and changes in the concentrations of a number of plasma proteins, including fibrinogen. They all cause alterations in haemodynamics, due in part to alteration in geometric resistance, but also to alterations in viscometric resistance as a result of changes in the haemorheological properties of the blood components locally and systemically. While some of these inflammation-induced changes are useful on a local level and assist in the resolution of the damaging factor and in tissue repair, the systemic haemorheological effects may lead to deleterious haemodynamics. Many of the effects are well documented but two new possibilities arise. One is the potential effects of fibrinogen heterogeneity on blood rheology, and the other the possible effects of leucocyte protease release on the aggregability of the red cell.