Plasmapheresis for hyperviscosity syndrome in macroglobulinemia Waldenström and multiple myeloma: influence on blood rheology and the microcirculation.

The efficacy of plasmapheresis in improving blood flow properties in patients with hyperviscosity syndrome was studied during 22 plasmapheresis treatments in four patients with hyperviscosity syndrome (three with macroglobulinemia Waldenström, one with multiple myeloma). Immediately before and after plasmapheresis (exchange volume 3 liters) the following parameters were determined: standard hematologic parameters, serum proteins, plasma viscosity, whole blood viscosity, and blood flow velocity in finger nailfold capillaries by video microscopy. The hematocrit remained unchanged. Paraprotein concentrations were markedly reduced by plasmapheresis (average 35%). Plasma viscosity fell from 5.0 +/- 3.3 cp to 2.1 +/- 1.0 cp (p less than 0.0001, normal range 1.1 to 1.4 cp). Whole blood viscosity changed accordingly. The plasma viscosity before plasmapheresis (x) determined the drop in viscosity after plasmapheresis, according to the following regression: y = 0.97 - 0.77 x; r = 0.962, p less than 0.001. The spontaneous capillary blood cell flow velocity increased from 0.33 +/- 0.14 mm/sec to 0.55 +/- 0.21 mm/sec (p less than 0.01) and the change in spontaneous flow velocity (y) was correlated with the change in plasma viscosity (x): y = 0.02 - 0.05 x; r = 0.833, n = 7, p less than 0.05. We conclude that plasma viscosity is a major determinant of capillary blood flow and that plasmapheresis is an efficient treatment of abnormal microcirculation caused by increased plasma viscosity. Our data make it possible to predict the benefit of plasmapheresis in a given situation and contribute to a better use of this valuable method.