I realize the image above may not be familiar to you, but our audiences come from varying backgrounds of medicine and may include critical care providers, nurses, and even physician extenders. On occasion we will post something that caters to a more advanced skill set. To set the stage on this week's topic, the image represents a peripheral blood smear. A drop of blood is placed and then smeared on a microscope slide. It is allowed to air dry and finally it is stained for viewing under a microscope at 50-100x magnification. Each cell lineage will stain differently. Red blood cells, various white blood cells, and platelets are all represented here.
The RBC's cover most of the background, the WBC's are larger, present in less quantity and stain more boldly. The platelets are stained deep purple and appear as pinpoint dots in the center of the field. This image has some immature WBC's in an increased quantity. Further testing would be necessary to determine if this represents an acute or chronic leukemia (blood cancer) Most of the time in a disease-free state your WBC should be between 3.7-10.3 x 10^3/ul. If an infection is present this count can be increased but will rarely exceed 50 x 10^3/ul. While this count is elevated during infections, it usually doesn't cause much problem with overall blood viscosity or its ability to flow within the vessels. The same cannot be said when the patient has certain types of acute or chronic leukemia. In rare instances, the WBC count can climb to over 350-400 x 10^3/ul.
As you can imagine when more and more WBC's are getting released from the bone marrow, it can cause some complications and crowd out the healthy cells. One obvious problem is called sludging. This sludging can be evident in the capillaries throughout the body as well as the microvasculature. The blood in these vulnerable areas becomes thick, sticky and flow can become very static. Neurological, pulmonary, and vision related symptoms are the most common areas/organs systems for concern. Leukostasis may cause various complications, including hyper viscosity syndrome, vascular occlusion resulting in intracranial hemorrhages and respiratory failure. WBC due to their size and nuclear complexity are not as pliable as RBC's so as you can imagine they are more likely to aggregate.
The fix besides systemic chemotherapy could be leukapheresis. While chemotherapy is the standard treatment for leukemia and can help reduce the number of leukemic cells, it can take several days after the first treatment for this effect to occur. In leukapheresis (aka: leukodepletion) your blood is taken from your body by a specialized apheresis machine, the WBC are separated and removed while the other remaining constituents of whole blood are given back to you. The process takes about 2-4 hours depending on the institution and the equipment they have. This relatively rapid treatment can provide some relief and reduce the risk of cardiovascular or cerebrovascular problems from blood clogging and subsequently compromising the smaller peripheral vessels/capillaries. The right chemo combination can certainly be started later. Leukapheresis provides a timely stop gap.
The treatment can be used on children and adults suffering from profound leukocytosis. The side effects are usually benign and transient -or- short term. If you have ever donated blood - the symptoms you experienced, then would be very similar with this treatment modality. A single leukapheresis can reduce the WBC by 20% to 50%... this can be significant.
As this sludging complication is a true emergency...I must note that more research is still needed on the efficacy of this particular treatment. There are no prospective, randomized studies, and retrospective studies report conflicting results, the role of leukapheresis for cell reduction is still very much unclear. Although patients often experience symptomatic relief, there appears to be no effect on long-term survival.
December 30, 2024
Author: Joshua Ishmael, MBA, MLS(ASCP)CM, NRP
Pass with PASS, LLC
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