A rapid and accurate method for estimating the erythrocyte sedimentation rate using a hematocrit-corrected optical aggregation index

Abstract

Although both the erythrocyte sedimentation rate (ESR) and optically measured erythrocyte aggregation parameters are affected by the hematocrit, this interaction is not considered by the method used to estimate ESR that considers aggregation parameters. In this study, we investigated the relationship between the ESR obtained by the Westergren method and that obtained with an aggregation parameter, namely, the aggregation index (AI) of multiple hematocrit values and fibrinogen-spiked samples with an analysis time of 5–60 s, and attempted to develop a rapid and accurate ESR estimation method. The AIs obtained from 5- and 10-s optical measurements with a fixed hematocrit were highly correlated with the erythrocyte sedimentation velocity. Furthermore, the rate of the AI increase with an increasing hematocrit was not significantly affected by the fibrinogen concentration at these measurement times. On the basis of these results, we defined the hematocrit-corrected aggregation index (HAI). The exponential function of the HAI obtained from the 5-s measurement agreed well with the sedimentation velocity calculated to eliminate the effect of hindered settling, and the HAI and hematocrit could be used to calculate the time constant of the sedimentation curve with a linear regression equation. The ESR value at 1 h was calculated based on the modified Stokes’ law and the HAI obtained from the 5-s measurement and showed an excellent correlation (R = 0.966) with the ESR value obtained by the Westergren method over a wide range of hematocrit and fibrinogen concentrations.

Determination of the erythrocyte sedimentation rate using the hematocrit‐corrected aggregation index and mean corpuscular volume

“…The Ht‐corrected HAI of the erythrocyte aggregation parameter AI obtained from the 5‐s syllectogram measured by our instrument was defined by Equation ( 6 ). 18 We reported that V s , obtained by dividing the observed V e by the hindered settling coefficient, agrees well with the value expressed in the following regression equation (Equation ( 7 )) using HAI. Here, a and b are coefficients and c is the settling velocity in the absence of aggregation, that is, V s .…”

“… 6 , 18 The other is that ESR is Ht dependently decreased due to the effect of hindered settling. 19 , 20 In our previous report, 18 we investigated the effect of Ht and analysis time on an aggregation parameter, namely the aggregation index (AI) determined from the syllectogram, and demonstrated that the effect of Ht on the AI measured over a 5‐s interval could be corrected as the Ht‐corrected AI (HAI) for samples with added fibrinogen. The sedimentation velocity obtained by eliminating the effect of hindered settling could be expressed by the exponential function of the HAI obtained from the 5‐s syllectogram.…”

“…Moreover, an accurate sedimentation curve could be obtained by calculation based on the modified Stokes' law and HAI. 18 However, that study used a limited number of fibrinogen concentration‐ and Ht‐adjusted blood samples from healthy volunteers, and the method has not been validated for clinical samples with various plasma proteins and varying mean corpuscular volumes (MCVs). Although ESR increases with an increasing MCV at fixed conditions of Ht and plasma, 21 no study has quantitatively evaluated the impact of MCV on the sedimentation rate equation for a variety of Ht values.…”

Novel blood typing method by discrimination of hemagglutination and rouleaux using an erythrocyte aggregometer

“…A previously reported device (MEK-1305; Nihon Kohden Corporation, Tokyo, Japan) was used to measure the syllectogram [17]. To dissociate aggregated RBCs, 60 L of blood was flowed at a shear rate of 335 s -1 through a glass cell (cross-sectional inner dimension, 0.8 × 0.8 mm) at 37 • C, and then the flow was abruptly stopped.…”

Biosensing of Haemorheological Properties Using Microblood Flow Manipulation and Quantification

“…The AI is estimated from the intensity of the blood flow image during the turn-off blood flow period [ 23 ]. More recently, Watanabe et al suggested hematocrit-corrected aggregation index for comparative study of erythrocyte sedimentation rate [ 27 ]. Kakei et al suggested an electrical impedance spectroscopy for monitoring RBC sedimentation in T-shaped container [ 28 ].…”