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Overview :
In severe falciparum malaria there is a microvascular
obstruction due to sequestration of parasitized erythrocytes. In addition, red
blood cell deformability is significantly reduced in severe malaria, which is
due mainly to changes in
unparasitized erythrocytes. Red
cell deformability is particularly low in fatal cases and can be used to
identify those patients at significant risk on admission to the hospital.
Patient Populations: Thai natives >= 14 years of age,
nonpregnant and without a history of previous antimalarial drug treatment within
24 hours of admission.
Test Method and Conditions:
• Technique:
ektacytometry
• Instrument:
laser-assisted optical rotational cell analyzer
• Shear stress
applied: 1.7 Pascal (approximates the shear stress encountered in vivo in the
venules)
• The unit of
deformability is the elongation index (EI).
Interpretation:
• A severely
reduced red cell deformability, as indicated by a red blood cell elongation
index < 0.21 on admission to the hospital, predicts a fatal outcome with a
sensitivity of 100% and specificity of 88%. Patients with fatal outcomes tended
to have EIs in the range of 0.16 to 0.20.
• Healthy
controls had EI of 0.25 to 0.32.
• Patients
with uncomplicated malaria had an EI from 0.22 to 0.32
• Patients
with severe but nonfatal malaria usually had an EI in the range of 0.22 to 0.31,
with a few showing an EI as low as 0.18.
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