Oncology nurses need to be aware of hyperviscosity syndrome (HVS), a rare but life-threatening oncologic emergency that can occur in patients with multiple myeloma (MM). HVS is most common in newly diagnosed patients with a high tumor burden, but it can also occur in patients experiencing relapse. As a result, all patients with MM are at risk for severe complications. Oncology nurses may be the first to identify the classic triad of HVS symptoms.
What Is Viscosity?
Viscosity is a measure of fluid’s resistance to flow. For blood, viscosity refers to its “thickness.” Normal blood flow relies on the balance between:
- Plasma (fluid portion) and
- Cellular components (most often red or white blood cells)
Blood flows easily with low viscosity. As the blood thickens, viscosity changes. Blood flow can become stagnant, a condition called “stasis.” Clots (thrombi) can form mainly in the microcirculation (arterioles, capillaries, and venules), leading to inadequate tissue perfusion.
How Does MM Cause HVS?
Cancer can affect blood viscosity in 2 main ways: (1) by increasing the number of blood cells (eg, in leukemia) or (2) by altering plasma with abnormal serum proteins (eg, in MM). Approximately 85% of HVS cases are caused by Waldenström macroglobulinemia (WM), a form of non-Hodgkin lymphoma (NHL). WM leads to the production of a large, abnormal, star-shaped immunoglobulin monoclonal protein called macroglobulin. Although rare, MM can also cause HVS.
In MM, the cancerous plasma cells make one specific type of antibody rather than a variety of immunoglobulins. This abnormal, nonfunctional monoclonal immunoglobulin (an M-protein or paraprotein) lacks infection-fighting ability. The type of MM depends on the abnormal immunoglobulin (paraprotein). IgG kappa is the most common type of MM, followed by IgA. Because these monoclonal proteins are much larger than usual, the kidney cannot effectively clear them from the bloodstream. These proteins thicken the blood, leading to increased viscosity.
What Is the HVS Triad of Symptoms for Early Recognition?
Decreased blood flow from increased viscosity leads to platelet aggregation, resulting in clot formation. Without platelets, bleeding becomes the most common symptom. In addition, blood stasis causes higher pressure and shear forces within blood vessels that can damage fragile vessel walls, resulting in spontaneous bleeding.
Symptoms vary, but the classic triad of HVS symptoms is:
- Mucosal bleeding: epistaxis, gingival, vaginal area, or skin manifestations (eg, excessive bruising), with potential cerebral or gastrointestinal (GI) bleeding
- Neurologic abnormalities: headaches, light-headedness, confusion, poor concentration, memory loss, tinnitus, hearing loss, vertigo, or in severe cases, stroke-like symptoms, seizures, somnolence, or coma.
- Visual disturbances: blurred vision, diplopia, or complete vision loss
Not every patient experiences the triad of symptoms. In a retrospective cohort study of 39 patients with newly diagnosed MM with HVS, 23% of patients had no symptoms, 59% had mild clinical signs (43% epistaxis, 33% blurred vision, and 23% headache), and 18% had severe neurologic symptoms.
A significant decrease in blood flow can lead to cardiopulmonary symptoms such as dyspnea, pulmonary edema, chest pain, or congestive heart failure. Without prompt recognition and treatment, HVS can lead to multi-organ system failure.
How Do Providers Diagnose HVS?
The diagnosis of HVS requires a combination of clinical and laboratory findings. Diagnosing HVS using a viscosity blood test can be challenging. Some patients may exhibit HVS symptoms with only slightly elevated viscosity levels, whereas others may have high viscosity but be asymptomatic. Therefore, a viscosity test primarily confirms suspected HVS. Ophthalmic exams often reveal dilated retinal veins resembling “sausages” or “box cars.”
How Do Providers Manage HVS?
Patients start therapeutic plasma exchange (TPE) immediately to prevent severe complications, such as thrombosis or GI or cerebral bleeding. During TPE, the patient’s plasma, which contains excess proteins, is rapidly replaced with fresh plasma or a plasma substitute to lower blood viscosity.
Overall, the goal is to treat the MM that is causing HVS. Treatment consists of rapid-acting high-dose steroids and systemic therapy.
HVS becomes an emergency when impaired circulation leads to potentially life-threatening inadequate tissue perfusion to vital organs. Without prompt treatment, HVS may cause multi-organ failure. Oncology nurses have a critical role in promptly communicating assessment findings to assist with an accurate diagnosis, early intervention, and appropriate treatment.
References
Microcirculation: Physiology, Pathophysiology, and Clinical Application
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