Sauna effects on hemorheology and other variables.

Acute sauna induces decreased blood fluidity as quantified by measurements of blood and plasma viscosity, hematocrit, red cell filterability, and aggregation. The effect is far less prominent when sauna treatment is continued regularly for eight weeks. In this case there are only minor changes in native blood viscosity and hematocrit together with slight variations in hematologic measurements, calcium, and serum protein pattern. Thus, from the hemorheology point of view, sauna leads to adverse effects predominantly acutely, while long-term effects seem negligible. Such aspects are worth considering in patients with high cardiovascular risks, and marked hypoperfusion.