Artificial Organs 14(6):413415, Raven Press, Ltd., New York 0 1990 International Society for Artificial Organs
Usefulness of Thrombelastography for Dosage Monitoring of Low Molecular Weight Heparin and Unfractionated Heparin During Hernodialysis Toshio Shinoda, Hideo Arakura, Masafumi Katakura, Toshihide Shirota, and "Seinosuke Nakagawa Shinshu University Hospital, Matsumoto, and *Tokyo Metropolitan Tama Geriatric Hospital, Tokyo, Japan
Abstract: Low molecular weight heparin (LMH) acts as an anticoagulation agent mainly through its anti-activated coagulation factor X (X,) activity. Thrombelastography (TEG) is expected to be useful to monitor the dosage of LMH during hemodialysis because reaction time on TEG (TEG-r) is considered to reflect blood thromboplastin formation time, which depends on the formation of X,. To test this possibility, we compared the usefulness of TEG, activated coagulation time (ACT), activated partial thromboplastin time (APTT), and anti-X, activity in 28 hemodialysis patients using both conventional unfractionated heparin (UFH) and LMH on separate dialysis procedures. Anti-X, activity of LMH was comparable to that of UFH when it was measured using both LMH and UFH as standards. Anti-X, activity, which theoretically depended on the heparin concentration in blood samples, did not correlate with the degree of dialyzer clotting. The
APTT correlated well with anti-X, activity in patients using LMH ( r = 0.686, p < 0.01) and UFH (r = 0.906, p < 0.01), but not with the degree of dialyzer clotting. The TEG-r correlated well with the degree of dialyzer clotting both in patients using LMH and those using UFH (measurements of samples obtained from the venous side of the extracorporeal circuit) and weakly correlated with anti-X, activity in patients using LMH (r = 0.402, p < 0.05). The ACT did not correlate with the degree of dialyzer clotting or anti-X, activity. These results suggest that TEG-r reflects the efficacy of heparin in the extracorporeal blood circuit, whereas APTT mainly reflects heparin concentration of the blood samples. It appears TEG is useful for dosage monitoring of LMH as well as UFH during hemodialysis. Key Words: Thrombelastography-Low molecular weight heparin-Anti-X, activityDialyzer clotting.
In the case of conventional unfractionated heparin (UFH), the major component of the anticoagulation effect consists of antithrombin and anti-activated coagulation factor X (X,) actions, whereas low molecular weight heparin (LMH), one of the constituents of UFH, possesses little antithrombin action. Reaction time on thrombelastography (TEG-r) has been considered to correspond to blood thromboplastin formation (1). Therefore, it is possible that the anti-X, effect of heparin can be monitored by prolongation of TEG-r. If this is the case, thrombelastography is especially useful for
dosage monitoring of LMH, because LMH causes little change in ordinary coagulation tests such as partial thromboplastin time and thrombin time (2). This point was investigated in patients receiving hemodialysis (HD). PATIENTS AND METHODS
Coagulation tests were carried out in 28 patients (18 men and 10 women, 50.7 ? 10.9 SD years) with chronic renal failure during HD using hollow-fiber dialyzers with regenerated cellulose membrane. The FR-860 (KabiVitrum AB, Sweden, kindly offered by Kissei Pharmaceutical Corporation Ltd., Matsumoto, Japan) was used as LMH, and Caprocin (Mitsui Pharmaceuticals Inc., Tokyo, Japan) as UFH. Heparin doses were from 300 to 1,620 anti-X, dose at the injection Of the units'h after a initiation.
Received February 1990; revised April 1990. Address correspondence and reprint requests to Dr. T. Shinoda, Hernodialysis Unit, Shinshu University Hospital, 1-1, Asahi 3-chome, Matsumoto 390, Japan. This work was presented in part at the VIIth World Congress of the International Society for Artificial Organs, Sapporo, Japan.
413
T . SHINODA ET AL.
414
Activated coagulation time (ACT) and activated partial thromboplastin time (APTT) were determined by the standard methods. The TEG was examined with Thrombelastrograph D (Hellige GMBH, F.R.G.). Anti-X, activity was measured by an amidolytic method using synthetic substrate S2222 (Testzym “Heparin” kit, Daiichi Pure Chemicals Co., Ltd., Tokyo, Japan), and both FR-860 and Caprocin were the standards. Blood samples were obtained from three points of the extracorporeal blood circuit (A, and A,, preheparin and postheparin infusion lines, respectively; V, postdialyzer) during HD. Dialyzer clotting was semiquantitively classified into five grades according to the number of clotted fibers after HD (0, a few; 1, up to several; 2, up to several dozens; 3, up to half of fibers; and 4, over half of fibers). Heparin dosage was gradually reduced until the dialyzer clotting became grade 3 or more.
RESULTS Anti-X, activities of blood samples obtained from patients given LMH, assayed with UFH and LMH themselves as standards, correlated well with each other (r = 0.986, p < 0.01). This was also the case when samples from those given UFH were analyzed (r = 0.987, p < 0.01). The ACT did not correlate with anti-X, activity in patients given LMH and UFH. The APTT correlated well with anti-X, activity in patients using LMH ( r = 0.686, p < 0.01) and UFH (r = 0.906, p < 0.01) (Fig. 1). When extremely high TEG-r values (over 100) were omitted, TEG-r correlated with anti-X, activity in those receiving LMH (r = 0.402, p < 0.05) (Fig. 2). It did not correlate with anti-X, in those using UFH. Dialyzer clotting was minimal (grades 0 and 1) when the TEG-r of V samples was kept longer than 20 min irrespective of the TEG-r of A, and A, samples in patients using LMH and UFH (Fig. 3). The ACT, APTT, and anti-X, activity of either A,, A,, or V samples did not show such cut-off points. CONSIDERATION
Anti-X, activity indicates heparin concentration of samples expressed as anti-X, units/ml because it is determined with sufficient amounts of exogenous factor X, and antithrombin 111. In this study, the anti-X, activities of LMH and UFH are considered equivalent, in contrast to a previous report (3). The difference might come from the difference in standards used. Anti-X, activity and APTT did not show a cut-off
Ariif Organs. Vol. 14, N o . 6 , 1990
*0°/ 150 -
0’ 0
’
‘
‘
’
’ ’ 0.5
*OOi t
’
’
”
1.0
150 t = 0.686
100
“0
0.5
1.0
anti - factor Xa (U/ml) FIG.1. Correlation between anti-activated coagulation factor X (antifactor X,) and activated partial thromboplastin time. Top and bottom panels depict the correlation between these two parameters in cases of unfractionated heparin (UFH, r = 0.906, p < 0.01) and low molecular weight heparin (LMH, r = 0.686, p < 0.01),respectively.
point to minimize dialyzer clotting, which is considered to reflect actual coagulability in the blood circuit, in either LMH or UFH usage. The APTT is mainly determined by heparin concentration of samples, as evidenced by the excellent correlation between anti-X, activity and APTT. Therefore, these results suggest that the concentration of heparin does not necessarily reflect its efficacy in the blood circuit. On the contrary, TEG-r did not correlate well with anti-X, activity but did show the cut-off point. Accordingly, it is suggested that the TEG-r of V samples is a useful parameter to minimize heparin dosage without increasing dialyzer clotting. It appears TEG-r reflects the efficacy of heparin in the blood circuit because it is measured under condi-
THROMBELASTOGRAPHY FOR HEPARIN DOSAGE IN HEMODIAL YSIS
.
200
h
[UFH I
-
100
.-C E 100 v
v
f Q (I
L
L
aI
l3
0 Y
v)
a
a,
n E
?
I I-
C 0
E"
.-
I-
C 0
.-+ u
Grade of Dialyzer Clotting 0- 1 2-3
200
.-C E
d
415
0 0
0.5
1.O
*1
t-
0 FIG. 3. Reaction time on thrombelastography (TEG-r) in two groups of dialyzer clotting. The A, and V denote samples from the points at preheparin infusion line and postdialyzer of the blood circuit, respectively. Open circles denote TEG-r values in patients given low molecular weight heparin, and closed circles those given unfractionated heparin. In group 1 (minor dialyzer clotting, grades 0 and 1).TEG-r values were significantly higher in V samples than in A, samples (68.3 2 44.7 versus 27.0 13.9 SD rnin, p < 0.01). In group 2 (moderate dialyzer clotting, grades 2 and 3), there was no difference in TEG-r values between V samples and A, samples (19.3 5 14.9 versus 11.8 rt 2.3 min). Heparin doses were not different between the two groups (765 i 196.1 versus 630.8 rt 186.6 U/ml).
100
*
(I
a, L1: w
0
w
0.5
1.0
a n t i - f a c t o r Xa (U/ml) FIG. 2. Correlation between anti-activated coagulation factor X (antifactor X), and reaction time on thrombelastography (TEG-r). Top and bottom panels depict the correlation between these two parameters in cases of unfractionated heparin (UFH) and low molecular weight heparin (LMH), respectively. These two parameters positively correlated ( r = 0.402, p < 0.05)in the case of LMH, when extremely high TEG-r values (over 100) were omitted. No correlation was observed in the case of UFH.
The correlation between TEG-r and anti-X, activity in patients given only LMH but not UFH may suggest that prolongation of TEG-r is mainly attributable to anti-X, action rather than antithrombin action of heparin.
CONCLUSION It appears TEG is useful for dosage monitoring of LMH as well as UFH during HD. REFERENCES
tions similar to the in vivo, using whole blood without exogenous activators of coagulation. There have been no previous reports on the usage of TEG for dosage monitoring of heparin during HD to our knowledge. On the other hand, ACT is considered not sensitive to both the concentration and the efficacy of heparin.
1. Von Kaulla KN. Quantitative methods for recording blood coagulation: theoretical and practical aspects. Progress in Hematology 1962;3:218-93. 2. Schrader J, Rieger J , Muschen H, et al. Anwendung von niedermolekularem Heparin bei Harnodialysepatienten. Klin Wochenschr 1985;63:49-55. 3. Barrowcliffe TW, Curtis AD, Tornlinson TP, Hubbard AR, Johnson EA, Thomas DP. Standardization of low molecular weight heparins: a collaborative study. Thromb Haemost 1985$4: 675-9.
Artif Organs, Vol. 14, N o . 6 , 1990
Usefulness of Thrombelastography for Dosage Monitoring of Low Molecular Weight Heparin and Unfractionated Heparin During Hernodialysis Toshio Shinoda, Hideo Arakura, Masafumi Katakura, Toshihide Shirota, and "Seinosuke Nakagawa Shinshu University Hospital, Matsumoto, and *Tokyo Metropolitan Tama Geriatric Hospital, Tokyo, Japan
Abstract: Low molecular weight heparin (LMH) acts as an anticoagulation agent mainly through its anti-activated coagulation factor X (X,) activity. Thrombelastography (TEG) is expected to be useful to monitor the dosage of LMH during hemodialysis because reaction time on TEG (TEG-r) is considered to reflect blood thromboplastin formation time, which depends on the formation of X,. To test this possibility, we compared the usefulness of TEG, activated coagulation time (ACT), activated partial thromboplastin time (APTT), and anti-X, activity in 28 hemodialysis patients using both conventional unfractionated heparin (UFH) and LMH on separate dialysis procedures. Anti-X, activity of LMH was comparable to that of UFH when it was measured using both LMH and UFH as standards. Anti-X, activity, which theoretically depended on the heparin concentration in blood samples, did not correlate with the degree of dialyzer clotting. The
APTT correlated well with anti-X, activity in patients using LMH ( r = 0.686, p < 0.01) and UFH (r = 0.906, p < 0.01), but not with the degree of dialyzer clotting. The TEG-r correlated well with the degree of dialyzer clotting both in patients using LMH and those using UFH (measurements of samples obtained from the venous side of the extracorporeal circuit) and weakly correlated with anti-X, activity in patients using LMH (r = 0.402, p < 0.05). The ACT did not correlate with the degree of dialyzer clotting or anti-X, activity. These results suggest that TEG-r reflects the efficacy of heparin in the extracorporeal blood circuit, whereas APTT mainly reflects heparin concentration of the blood samples. It appears TEG is useful for dosage monitoring of LMH as well as UFH during hemodialysis. Key Words: Thrombelastography-Low molecular weight heparin-Anti-X, activityDialyzer clotting.
In the case of conventional unfractionated heparin (UFH), the major component of the anticoagulation effect consists of antithrombin and anti-activated coagulation factor X (X,) actions, whereas low molecular weight heparin (LMH), one of the constituents of UFH, possesses little antithrombin action. Reaction time on thrombelastography (TEG-r) has been considered to correspond to blood thromboplastin formation (1). Therefore, it is possible that the anti-X, effect of heparin can be monitored by prolongation of TEG-r. If this is the case, thrombelastography is especially useful for
dosage monitoring of LMH, because LMH causes little change in ordinary coagulation tests such as partial thromboplastin time and thrombin time (2). This point was investigated in patients receiving hemodialysis (HD). PATIENTS AND METHODS
Coagulation tests were carried out in 28 patients (18 men and 10 women, 50.7 ? 10.9 SD years) with chronic renal failure during HD using hollow-fiber dialyzers with regenerated cellulose membrane. The FR-860 (KabiVitrum AB, Sweden, kindly offered by Kissei Pharmaceutical Corporation Ltd., Matsumoto, Japan) was used as LMH, and Caprocin (Mitsui Pharmaceuticals Inc., Tokyo, Japan) as UFH. Heparin doses were from 300 to 1,620 anti-X, dose at the injection Of the units'h after a initiation.
Received February 1990; revised April 1990. Address correspondence and reprint requests to Dr. T. Shinoda, Hernodialysis Unit, Shinshu University Hospital, 1-1, Asahi 3-chome, Matsumoto 390, Japan. This work was presented in part at the VIIth World Congress of the International Society for Artificial Organs, Sapporo, Japan.
413
T . SHINODA ET AL.
414
Activated coagulation time (ACT) and activated partial thromboplastin time (APTT) were determined by the standard methods. The TEG was examined with Thrombelastrograph D (Hellige GMBH, F.R.G.). Anti-X, activity was measured by an amidolytic method using synthetic substrate S2222 (Testzym “Heparin” kit, Daiichi Pure Chemicals Co., Ltd., Tokyo, Japan), and both FR-860 and Caprocin were the standards. Blood samples were obtained from three points of the extracorporeal blood circuit (A, and A,, preheparin and postheparin infusion lines, respectively; V, postdialyzer) during HD. Dialyzer clotting was semiquantitively classified into five grades according to the number of clotted fibers after HD (0, a few; 1, up to several; 2, up to several dozens; 3, up to half of fibers; and 4, over half of fibers). Heparin dosage was gradually reduced until the dialyzer clotting became grade 3 or more.
RESULTS Anti-X, activities of blood samples obtained from patients given LMH, assayed with UFH and LMH themselves as standards, correlated well with each other (r = 0.986, p < 0.01). This was also the case when samples from those given UFH were analyzed (r = 0.987, p < 0.01). The ACT did not correlate with anti-X, activity in patients given LMH and UFH. The APTT correlated well with anti-X, activity in patients using LMH ( r = 0.686, p < 0.01) and UFH (r = 0.906, p < 0.01) (Fig. 1). When extremely high TEG-r values (over 100) were omitted, TEG-r correlated with anti-X, activity in those receiving LMH (r = 0.402, p < 0.05) (Fig. 2). It did not correlate with anti-X, in those using UFH. Dialyzer clotting was minimal (grades 0 and 1) when the TEG-r of V samples was kept longer than 20 min irrespective of the TEG-r of A, and A, samples in patients using LMH and UFH (Fig. 3). The ACT, APTT, and anti-X, activity of either A,, A,, or V samples did not show such cut-off points. CONSIDERATION
Anti-X, activity indicates heparin concentration of samples expressed as anti-X, units/ml because it is determined with sufficient amounts of exogenous factor X, and antithrombin 111. In this study, the anti-X, activities of LMH and UFH are considered equivalent, in contrast to a previous report (3). The difference might come from the difference in standards used. Anti-X, activity and APTT did not show a cut-off
Ariif Organs. Vol. 14, N o . 6 , 1990
*0°/ 150 -
0’ 0
’
‘
‘
’
’ ’ 0.5
*OOi t
’
’
”
1.0
150 t = 0.686
100
“0
0.5
1.0
anti - factor Xa (U/ml) FIG.1. Correlation between anti-activated coagulation factor X (antifactor X,) and activated partial thromboplastin time. Top and bottom panels depict the correlation between these two parameters in cases of unfractionated heparin (UFH, r = 0.906, p < 0.01) and low molecular weight heparin (LMH, r = 0.686, p < 0.01),respectively.
point to minimize dialyzer clotting, which is considered to reflect actual coagulability in the blood circuit, in either LMH or UFH usage. The APTT is mainly determined by heparin concentration of samples, as evidenced by the excellent correlation between anti-X, activity and APTT. Therefore, these results suggest that the concentration of heparin does not necessarily reflect its efficacy in the blood circuit. On the contrary, TEG-r did not correlate well with anti-X, activity but did show the cut-off point. Accordingly, it is suggested that the TEG-r of V samples is a useful parameter to minimize heparin dosage without increasing dialyzer clotting. It appears TEG-r reflects the efficacy of heparin in the blood circuit because it is measured under condi-
THROMBELASTOGRAPHY FOR HEPARIN DOSAGE IN HEMODIAL YSIS
.
200
h
[UFH I
-
100
.-C E 100 v
v
f Q (I
L
L
aI
l3
0 Y
v)
a
a,
n E
?
I I-
C 0
E"
.-
I-
C 0
.-+ u
Grade of Dialyzer Clotting 0- 1 2-3
200
.-C E
d
415
0 0
0.5
1.O
*1
t-
0 FIG. 3. Reaction time on thrombelastography (TEG-r) in two groups of dialyzer clotting. The A, and V denote samples from the points at preheparin infusion line and postdialyzer of the blood circuit, respectively. Open circles denote TEG-r values in patients given low molecular weight heparin, and closed circles those given unfractionated heparin. In group 1 (minor dialyzer clotting, grades 0 and 1).TEG-r values were significantly higher in V samples than in A, samples (68.3 2 44.7 versus 27.0 13.9 SD rnin, p < 0.01). In group 2 (moderate dialyzer clotting, grades 2 and 3), there was no difference in TEG-r values between V samples and A, samples (19.3 5 14.9 versus 11.8 rt 2.3 min). Heparin doses were not different between the two groups (765 i 196.1 versus 630.8 rt 186.6 U/ml).
100
*
(I
a, L1: w
0
w
0.5
1.0
a n t i - f a c t o r Xa (U/ml) FIG. 2. Correlation between anti-activated coagulation factor X (antifactor X), and reaction time on thrombelastography (TEG-r). Top and bottom panels depict the correlation between these two parameters in cases of unfractionated heparin (UFH) and low molecular weight heparin (LMH), respectively. These two parameters positively correlated ( r = 0.402, p < 0.05)in the case of LMH, when extremely high TEG-r values (over 100) were omitted. No correlation was observed in the case of UFH.
The correlation between TEG-r and anti-X, activity in patients given only LMH but not UFH may suggest that prolongation of TEG-r is mainly attributable to anti-X, action rather than antithrombin action of heparin.
CONCLUSION It appears TEG is useful for dosage monitoring of LMH as well as UFH during HD. REFERENCES
tions similar to the in vivo, using whole blood without exogenous activators of coagulation. There have been no previous reports on the usage of TEG for dosage monitoring of heparin during HD to our knowledge. On the other hand, ACT is considered not sensitive to both the concentration and the efficacy of heparin.
1. Von Kaulla KN. Quantitative methods for recording blood coagulation: theoretical and practical aspects. Progress in Hematology 1962;3:218-93. 2. Schrader J, Rieger J , Muschen H, et al. Anwendung von niedermolekularem Heparin bei Harnodialysepatienten. Klin Wochenschr 1985;63:49-55. 3. Barrowcliffe TW, Curtis AD, Tornlinson TP, Hubbard AR, Johnson EA, Thomas DP. Standardization of low molecular weight heparins: a collaborative study. Thromb Haemost 1985$4: 675-9.
Artif Organs, Vol. 14, N o . 6 , 1990
