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Common haematological emergency. Defined as increase in whole blood viscosity as a result of an increase in either red cells, white cells or plasma components, usually Ig.

Commonest situations arise as a result of

• 4 in red cell volume in polycythaemia rubra vera.

• High blast cell numbers in peripheral blood e.g. AML or ALL at presentation.

• Presence of monoclonal Ig e.g. Waldenstrom's macroglobulinaemia (IgM).

Clinical features—polycythaemia (e.g. PRV)

• Lethargy, itching, headaches, hypertension, plethora, arterial thromboses viz: MI, CVA and visual loss (central retinal artery occlusion).

^ Emergency treatment

Isovolaemic venesection. Remove 500mL blood volume from large bore vein (antecubital usually) with simultaneous replacement into another vein of 500mL 0.9% saline. Repeat daily until PCV <0.45.

Clinical features—high WBC (e.g. AML)

• Dyspnoea and cough (pulmonary leucostasis); confusion, 5 conscious level, isolated cranial nerve palsies (cerebral leucostasis), visual loss (retinal haemorrhage or CRVT).

^ Emergency treatment

• Unless machine leucapheresis can be obtained immediately, venesect 500mL blood from large bore vein and replace isovolaemically with packed red cells if Hb <7.0g/dL—otherwise replace with 0.9% saline to avoid increasing whole blood viscosity.

• Arrange leucapheresis on cell separator machine. Use white cell interface programme to apherese with replacement fluids depending on Hb as above. 2h is usually maximum tolerated.

• Initiate tumour lysis prophylactic protocol (see p560) in preparation for chemotherapy.

• Start chemotherapy as soon as criteria allow (high urine volume of pH>8 and allopurinol commenced). This is crucial as leucapheresis in this situation is only a holding manoeuvre while the patient is prepared for chemotherapy.

• Continue leucapheresis daily until leucostasis symptoms resolved or until WBC <50 x 109/L.

Hypergammaglobulinaemia (e.g. Waldenstrom's)

Lethargy, headaches, memory loss, confusion, vertigo, visual disturbances from cerebral vessel sludging—rarely MI, CVA.

^ Emergency treatment

• Unless immediate access to plasma exchange machine available, venesect 500mL blood from large bore vein with isovolaemic replacement with 0.9% saline unless Hb <7.0g/dL when use packed red cells.

• Arrange plasmapheresis on a cell separator machine using plasma exchange programme (see p584). Replacement fluids on criteria as above. Aim for 1-1.5 x blood volume exchange (usually 2.5-4.0L)

starting at lower end of range initially. Repeat daily until symptoms resolved.

• Maintenance plasma exchanges at 3-6 weekly intervals may be sufficient treatment for some forms of Waldenstrom's macroglobuli-naemia. However, if hyperviscosity due to IgA myeloma or occasionally IgG myeloma, chemotherapy will need to be initiated.

Note

Diseases in which the abnormal Ig shows activity at lower temperature e.g. cold antibodies associated with CHAD (see p118) require maintenance of plasmapheresis inlet and outlet venous lines and all infusional fluids at 37°C. Polyclonal 4 in Ig (e.g. some forms of cryoglobulinaemia) can also rarely cause hyperviscosity symptoms. Management is as above for monoclonal immunoglobulins.

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