Re-Evaluation of Trapped Plasma in the Microhematocrit Determination

摘要

Trapped plasma is that amount of intracellular plasma remaining in the packed cell column of the microhematocrit after centrifugation. It artificially increases the packed cell column constituting a positive bias to the hematocrit. The amount of trapped plasma varies as a function of cell packing. Foremost are the physical forces applied in the microhematocrit determination. The speed of the centrifuge and length of time of centrifugation are the major contributors. Cell packing is also dependent on the deformability of the cell, an intrinsic property of the erythrocyte. To a lesser extent, trapped plasma is affected by factors such as the anticoagulant used and plasma osmolality.