Fig 1.
Laser speckle rheology (LSR) instrument and coagulation parameters.
(A) The schematic diagram of the LSR instrument used for blood coagulation assessment. Polarized light (690 nm, 9 mW) from a diode laser (Newport Corp., LPM690-30C) was focused (spot size 100 μm) on the imaging chamber containing 127 μl of kaolin-activated blood. Cross-polarized laser speckle patterns were acquired at 180° back-scattering geometry via a beam-splitter using a high speed CMOS camera (Basler AG, acA2000-340km) equipped with a focusing lens (Edmund Optics, NT59-872)[14]. The captured speckle patterns were transferred to a computer for further processing. (B) Representative clot viscoelasticity profile derived using LSR. The relative change in clot viscoelasticity (G) is measured during coagulation and plotted as a function of time to retrieve the LSR coagulation parameters, R, K, α-angle and MA. Reprinted from [Tripathi MM, Hajjarian Z, Van Cott ME, and Nadkarni KS. Assessing blood coagulation status with laser speckle rheology. Biomed. Opt. Express. 2014. 5: 817–831] under a CC BY license, with permission from [The Optical Society], original copyright [2014].
Table 1.
LSR coagulation parameters: Descriptions and definition.
Fig 2.
Effect of warfarin treatment on correlations between LSR and aPTT, PT, INR and TEG parameters.
Coagulation profiles of 12 patients on warfarin therapy were evaluated using LSR and TEG, and with aPTT and PT/INR assays. LSR clotting time (R+K) parameter was compared to aPTT (A), PT (B), INR (C), and TEG R+K time (D). Furthermore LSR and TEG parameters angle (E) and MA (F) were compared. In Figs (B-F) data from all 12 patients is reported. For Fig (A), N = 11 patients are reported as aPTT was not obtained for one patient.
Fig 3.
Dose-dependent clot viscoelasticity profiles measured by LSR and TEG.
Clot formation of recalcified and kaolin-activated citrated whole blood was measured in the presence of heparin (0.3 USP/ml), argatroban (15.2μM) or rivaroxaban (2.29 μM) and compared with control samples (samples without anticoagulants). In all cases, dose-dependent changes in clot viscoelasticity profiles are noted by both LSR (solid curves) and TEG (dashed curves). The LSR profile trends closely mirror those measured by standard TEG.
Fig 4.
Effect of heparin on LSR and TEG coagulation parameters.
Blood coagulation parameters including the clotting time (R+K), the clot progression (angle) and the maximum amplitude (MA) were measured using LSR and TEG for 20–60 minutes following kaolin-activation of swine whole blood samples spiked with heparin at concentration 0 (control), 0.1, 0.2, 0.25, 0.3 USP/ml (A-C). Linear regression analysis between TEG and LSR coagulation parameters at each concentration was performed (D-F). Each data point represents the mean of three replications ± standard deviation (SD) (histograms) or standard error of the mean, SEM (linear regression). Values were compared between control samples (without treatment) and heparin treated samples using ANOVA followed by the Tukey’s method for multiple comparisons post-tests. * p<0.05,** p<0.01, *** p<0.001, **** p<0.0001.
Fig 5.
Effect of argatroban on LSR and TEG coagulation parameters.
Kaolin-activated swine blood spiked with 0 (control), 3.8, 5.7, 7.6, 15.2 μM argatroban was measured for 20–50 minutes and blood coagulation parameters including the clotting time (R+K), the clot progression (angle) and the maximum amplitude (MA) were extracted for each concentration (A-C). Correlation between LSR and TEG was evaluated using linear regression analysis (D-F). Each data point represents the mean of three replications ± SD (histograms) or standard error of the mean, SEM (linear regression). Values were compared between control samples (without treatment) and argatroban treated samples using ANOVA followed by the Tukey’s method for multiple comparisons post-tests. * p<0.05, ** p<0.01, *** p<0.001, **** p<0.0001.
Fig 6.
Effect of rivaroxaban on coagulation parameters extracted from LSR and TEG.
Kaolin-activated swine blood spiked with 0 (control), 0.46, 1.15, 1.73, 2.29 μM rivaroxaban was measured for 30–45 minutes and blood coagulation parameters including the clotting time (R+K), the clot progression (angle) and the maximum amplitude (MA) were extracted at these concentrations (A-C). Linear regression analysis was performed to analyze correlation between TEG and LSR (B-F). Each data point represents the mean of three replications ± SD (histograms) or standard error of the mean, standard error of the mean, SEM (linear regression). Values were compared between control samples (without treatment) and rivaroxaban treated samples using ANOVA followed by the Tukey’s method for multiple comparisons post-tests. * p<0.05, ** p<0.01, *** p <0.001, **** p<0.0001.
Fig 7.
Effect of haemodilution on LSR and TEG clot viscoelasticity profiles and parameters.
Recalcified and kaolin-activated swine whole blood diluted at 0 (undiluted blood sample) 40, 50, 60 or 70% were measured using LSR (A) and TEG instruments (B) and blood coagulation parameters such as the clotting time (R+K) (C), the clot progression (angle) (D) and the maximum amplitude (MA) (E) were extracted at various haemodilution concentrations. Linear regression analysis comparing blood coagulation parameters R+K (F) angle (G), and MA (H) between LSR and TEG are presented. Each data point represents the mean of three replications ± SD (histograms) or standard error of the mean, SEM (linear regression). Comparisons were done using ANOVA followed by the Tukey’s method for multiple comparisons. (*, 0%-…); ($, 40%-…); (&, 50%-…); (#, 60–70%). * p<0.05, ** p<0.01, *** p<0.001, **** p<0.0001.