![]() ![]() Plasma exchange reduces plasma viscosity approximately 20% to 30% per session. Plasmapheresis can be carried out daily initially and then spaced out at longer intervals to keep the viscosity below the symptomatic threshold for that particular patient. 1, 12, 16, 30 However, plasma exchange does not affect the underlying disease process, and so chemotherapy is often begun concomitantly. Some WM patients can be managed predominately with plasmapheresis. 29 Retinal examination findings correlate with symptomatic threshold for HVS in WM patients. 28 Plasmapheresis can reverse HVS-induced retinal changes promptly, including reducing retinal venous diameter and increased venous blood viscosity. Because bleeding is the most common sign of HVS, urgent plasmapheresis using a cell separator should be carried out for patients experiencing visual symptoms to reduce the likelihood of blindness from retinal hemorrhages/retinal detachment. A relatively small reduction in IgM concentration has a significant effect on lowering serum viscosity. 14, 21, 22 This procedure remains effective short-term treatment for HVS in WM because of the demonstrated correlation between IgM levels and serum viscosity and the 80% intravascular location of IgM. Plasmapheresis, first carried out manually for macroglobulinemia in the late 1950s, was demonstrated to reverse retinopathy and other clinical manifestations in most patients with HVS. 12, 14, 16-18 Protein coating also contributes to a platelet functional defect that further accentuates the bleeding tendency. 1, 12, 14-18, 20-22 In addition to raising plasma viscosity, macroglobulin coats red cells, leading to the characteristic stacking appearance (rouleaux) on peripheral blood smear in WM patients. Prompt diagnosis of HVS from the eye examination enables the institution of appropriate therapy (ie, plasmapheresis). Hemorrhages, exudates, microaneurysms, papilledema, and an appearance indistinguishable from central retinal vein occlusion may be seen in later stages. 1, 12, 14-18 The HVS can be diagnosed from the physical examination by the funduscopic finding of marked retinal venous engorgement resembling hot dogs on a string (ie, “sausaging” 12, 14-18, 20 Figure 1). 7, 8 However, viscosity values correlate closely with signs and symptoms in the same patient (“symptomatic threshold”). Such variation is the result, in part, of the previously mentioned wide range of intrinsic viscosity values noted in monoclonal macroglobulins. Viscosity levels in HVS vary significantly between patients. ![]()
0 Comments
Leave a Reply. |