The rheological properties of blood are influenced by red blood cell (RBC) mechanics and cell-cell aggregates, which yield important clinical information; however, measurement of rheological parameters is often not possible at phlebotomy-sites. We investigated the effect of short-term storage on the stability of RBC aggregation and deformability. Blood was obtained from apparently healthy volunteers and anticoagulated with lithium heparin or ethylenediaminetetraacetic acid (EDTA). Samples were stored either at ambient (22 °C) or cold (4 °C) temperature for up to 48 h. Aggregation and deformability were measured utilising light transmission and laser backscatter methods, and laser diffractometry, respectively. EDTA significantly lowered aggregation when compared with heparin-anticoagulated blood. During ambient temperature storage, EDTA preserved baseline RBC aggregation for up to 4 h, while lithium heparin-anticoagulated blood showed significant changes within 1 h. Deformability was altered after 8 h of storage, irrespective of anticoagulant. Cold storage extended stability most effectively in EDTA. It remains that EDTA should be the anticoagulant of choice to preserve blood physical properties. Even short-term storage of blood has a remarkable impact on physical properties; when unavoidable, however, EDTA blood should be stored at 4 °C for same day testing without negative effect.
Kuck et al. (Tue,) studied this question.