Thromboelastometry versus free-oscillation rheometry and enoxaparin versus tinzaparin: an in-vitro study comparing two viscoelastic haemostatic tests’ dose-responses to two low molecular weight heparins at the time of withdrawing epidural catheters from ten patients after major surgery

Table 1 Rotational thromboelastometry (ROTEM) and free-oscillation rheometry (FOR) results at varying concentrations of enoxaparin and tinzaparin

	Manufacturer’s reference range	0 IU/mL	Enoxaparin	Enoxaparin	Enoxaparin	Tinzaparin	Tinzaparin	Tinzaparin	Enoxaparin vs Tinzaparin	Enoxaparin	Tinzaparin
	Manufacturer’s reference range	0 IU/mL	0.5 IU/mL	1.0 IU/mL	1.5 IU/mL	0.5 IU/mL	1.0 IU/mL	1.5 IU/mL	ANOVA❖	Spearman (Rho, P)	Spearman (Rho, P)
ROTEM
CT (s)	100-240	178 ± 38	191 ± 89	214 ± 109	249 ± 94	223 ± 53	289 ± 84	326 ± 125	P < 0.01	0.62, P < 0.01	0.70, P < 0.01
CFT (s)	30-110	77 ± 23	87 ± 21	85 ± 16	83 ± 22	74 ± 27	84 ± 45	80 ± 21	P < 0.05	N/S	N/S
Angle (°)	70-83	75 ± 4	74 ± 4	75 ± 3	73 ± 4	75 ± 5	73 ± 5	73 ± 4	N/S	N/S	N/S
MCF (mm)	50-72	62 ± 5	61 ± 7	63 ± 5	63 ± 6	68 ± 7	64 ± 8	65 ± 6	N/S	N/S	N/S
ML (%)	<15	8 ± 4	6 ± 3	5 ± 4	2 ± 5	5 ± 4	6 ± 4	2 ± 4	N/S	−0.36, P < 0.05	N/S
FOR (ReoRox)
COT1 (s)	20-35	30 ± 5	35 ± 7	39 ± 8	38 ± 11	36 ± 4	45 ± 9	48 ± 15	P < 0.01	0.58, P < 0.01	0.77, P < 0.01
COT2 (s)	30-90	65 ± 11	76 ± 13	82 ± 14	85 ± 20	74 ± 5	91 ± 16	108 ± 29	N/S	0.54, P < 0.01	0.84, P < 0.01
COT2-COT1 (s)	10-55	34 ± 13	41 ± 8	43 ± 9	46 ± 10	38 ± 4	46 ± 11	51 ± 15	P < 0.05	0.47, P < 0.01	0.79, P < 0.01
Slope (Pa/min)	45-145	99 ± 87	121 ± 82	126 ± 88	132 ± 76	118 ± 90	138 ± 94^*	109 ± 88	P < 0.01	N/S	N/S
G’max (Pa)	770-2180	1629 ± 617	1777 ± 662	1831 ± 701	1612 ± 612	1656 ± 692	2069 ± 665	1615 ± 641	N/S	N/S	N/S
Clot SR (%)	10-25	17 ± 4	14 ± 5	16 ± 4	13 ± 6	15 ± 5	13 ± 6	11 ± 7	N/S	N/S	−0.41, P < 0.05

Results are presented as median ± SD. The significances of differences between individual concentrations, and between enoxaparin and tinzaparin at equal concentrations, are shown in Figs. 2 and 3, which display the results diagrammatically. ❖The significance of differences between results for enoxaparin and tinzaparin, corrected for concentration and individual, were assessed by Friedman’s analysis of variance (ANOVA). A brief explanation of the above tests follows. Measures of clot initiation: ROTEM-CT (clot time) and FOR-COT1 and -COT2. Measures of clot propagation: ROTEM-CFT and –alpha angle; and FOR-(COT2-COT1) and –Slope. Measures of clot structure: ROTEM-MCF and FOR-G’max. Measures of fibrinolysis: ROTEM-ML and FOR-Clot SR
*indicates a significant inter-class difference with p < 0.05

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