A comparison of capillary and venous blood sampling methods for the use in haemorheology studies

There is accumulating evidence that exercise may improve disturbed haemorheological parameters that are typically observed in various chronic diseases, thus there is a growing interest in exploring the influence of various exercise models for the improvement of haemorheology. Blood sampling using venipuncture, however, can be limiting during exercise and/or in field settings. The purpose of the present study was to investigate whether venous and capillary blood samples yield comparable red blood cell (RBC) deformability and aggregation indices. Twelve healthy volunteers (6 males and 6 females; age 30 +/- 9 yrs; body mass index 24.9 +/- 2.8 kgm(-2)) provided blood samples that were collected simultaneously from: i) a prominent forearm vein by venipuncture; ii) the earlobe using a lancet; iii) the middle finger using a lancet. Haematocrit, RBC deformability (Rheoscan-D, Sewon Meditech Inc., Korea) and RBC aggregation (Myrenne GmbH, Roetgen, Germany) were measured for each sample. Haematocrit and RBC deformability were not different between the three sampling sites, and the group averages of RBC aggregation parameters were not different between the three sampling methods. The time course of RBC aggregation was slower when using blood sampled from the earlobe, and there was stronger agreement between RBC aggregation parameters measured using venous and capillary finger samples compared with venous and earlobe. It is suggested that capillary blood sampling from the finger may provide a reliable alternative to venous blood sampling in clinical and field settings.