Micro-vibrational erythrocyte sedimentation rate (ESR) for sensitive measurement of erythrocyte aggregation

Abstract

The erythrocyte sedimentation rate (ESR) can act as a useful index of nonspecific disease activity in the diagnosis of inflammatory conditions. However, there are several drawbacks, including long time measurement. To promote ESR tendency, a micro-vibrational erythrocyte sedimentation rate (MV-ESR) was proposed. By controlling the profile of injecting flow rate into blood sample, air between the syringe pump and bottom of blood column was compressed and released. Micro-vibration (MV) is simple reciprocating flow including motion in both positive and negative directions in a line. It is determined as the edge of the interface between top of blood column and air is pinned under the pressure wave. From that, shear rate generated by determined MV is from 0 to 10–2 (s−1) in this study. Extremely low shear conditions may enhance the probability of erythrocyte aggregation formation. During measurement, a meniscus of separated plasma and sedimented erythrocytes was recorded using a camera. For validation of the proposed MV-ESR method, the effects of hematocrit as well as the frequency and amplitude of flow in the sedimentation tube were investigated. To quantify the enhancement of MV-ESR, the area of relative gradient (ARG) based on a relative gradient of 1 was used. When MV with a maximum flow rate of 1 mL/min and a period of 100 ms was produced until 15 min, MV-ESR exhibited the best performance. Then, the proposed technique was used to diagnose the ESR difference between a normal and periodontitis patient. The characteristic time (λESR), indicating the degree completion of the erythrocyte sedimentation, of the periodontitis patients was lower than that of the control. Based on the experimental demonstrations, λESR of the MV-ESR method has significant potential in the diagnosis of inflammatory conditions and prognosis of non-inflammatory conditions.