Analysis of Heparinization Methods during Hemodialysis
INGEBRIGT TALSTAD, M.D. AND KARSTEIN KJELBY, B.SC.
The ideal iriethod of heparinization should achieve therapeutic
concentrations (0.2-0.5 IU/mL) in the artificial kidney and
the least possible amount of heparin in the patient. Total
heparinization using a bolus dose (8400 IU) followed by
continuous infusion of heparin (20 IU/min), initially showed
1.4-2.4 IU/mL in the artificial kidney and the patient, but
unpredictable slopes. High-dose regional heparinization (120144 IU/min) and neutralization showed sustained heparin
concentrations (0.4-0.6 IU/mL) in the artificial kidney, and
<0.2 IU/mL in the patient. Low-dose regional heparinization
(25 IU/min) initially showed 0.25-0.45 IU/mL in the artificial
kidney, but unpredictable slopes in the patient. Low-dose
regional heparinization (25 IU/min) and neutralization showed
sustained heparin concentrations (0.15-0.35 IU/mL) in the
artificial kidney and <0.I5 IU/mL in the patient. (Key words:
Heparin; Hemodialysis; Kidney failure) Am J Clin Pathol
1985; 84: 317-322
THE ANTICOAGULANT used in hemodialysis may
exaggerate the bleeding tendency;12 however, some kind
of anticoagulation is needed to avoid clotting of the
artificial kidney. Heparin is the commonly used anticoagulant, but still there is no agreement as to which
heparinization method is preferable. The following heparinization methods have been recommended: total heparinization using a bolus injection of 2,500-8,000 IU
heparin followed by continuous 4 Or intermittent 5 ' 913,22
infusion of 1,200-1,500 IU heparin/hour. High-dose
regional heparinization combined with neutralization6
is riot widely used because of technical difficulties in
balancing heparin versus protamine sulfate.14 Intermittent, low-dose heparinization based on bedside
heparin monitoring, has been widely used in recent
years.8'913,19,20'22 Hemodialysis using prostacyclin without
heparin, has been used in a few patients.23,24
The ideal method of heparinization should prevent
clotting of the artificial kidney and not increase the
bleeding tendency of the patient. The present study
analyzes which of the heparinization methods may be
preferable based on heparin kinetics. The suggested
therapeutic range for heparin is 0.2-0.5 IU/mL." However, the minimal heparin-concentrations needed to
avoid clotting of the artificial kidney, may be as low as
0.1 iU/mL. Even less heparin has been used, but clotting
of the artificial kidney may occur.13 The therapeutic
Received October 2, 1984; received revised manuscript and accepted
for publication February 25, 1985.
Address reprint requests to Dr. Talstad: N-5016 Haukeland Hospital,
Bergen, Norway.
317
Divisions of Hematology and Nephrology, Medical
Department, Haukeland Hospital, University of Bergen,
Bergen, Norway
ranges of heparin that may prevent local platelet adhesion
and fibrin deposits2 have not been defined.
Materials and Methods
Theoretic Approach
Predicted Heparin Concentrations (Hp). Heparin is
distributed in the plasma volume of whole blood, which
in the mean, equals 42 mL/kg body weight (w).17 The
heparin concentration (H p ) following a bolus injection
of heparin (H), can be predicted as follows:
H p = H/(42 w + 300[1 - PCV])
where 300(1 — PCV) is the volume of the dialysis unit
corrected for the packed cell volume (PCV).
The H p at a constant regional infusion rate of heparin
(h IU/min), can be predicted:
H p = h/F(l - PCV)
where F is the blood flow rate (mL/min).
Heparin Neutralization in Vitro. The neutralization
of heparin with protamine sulfate, performed as described
for polybrene elsewhere,15 resulted in neutralization of
heparin at the ratio 7.63 mg protamine sulfate/1,000 IU
heparin.
Heparin Neutralization in Vivo. This was studied in
six patients by injecting 100 mg protamine sulfate;
protamine sulfate was assayed indirectly by the capacity
of plasma to neutralize heparin. Heparin 1 IU/mL
plasma was obtained by mixing 0.1 mL 10 IU/mL
heparin solution with 0.9 mL plasma. Heparin, not
being neutralized by protamine sulfate, was measured
by the S-2222 assay. The mean half-life of protamine
sulfate in vivo was 5.3 min (Fig. i). Because of the rapid
clearance and the great dilution of protamine sulfate in
the patient, recirculation should be negligible. There is
no loss of heparin across the dialysis membrane. 3 The
neutralization of heparin by protamine sulfate administered at the venous side of the artificial kidney (after
the bubbling chamber), is presumed to follow the in
vitro neutralization kinetics, since neutralization takes
place before protamine sulfate reaches the patient.
TALSTAD AND KJELBY
318
A.J.C.P. • September 1985
Heparin ( U / m l )
p H N - S - 2222
1.0- \
FIG. 1. Protamine sulfate kinetics.
Protamine sulfate (100 mg) was
given intravenously to six patients
during 1-2 minutes. Blood samples
were collected every second min,
and protamine sulfate was quantified by measuring the capacity of
plasma to neutralize heparin (see
Methods).
Protaminesulphate
100 mg
mm.
Materials
Patients on routine hemodialysis or hemofiltration
were selected for this study; informed consent was
obtained from the patients. For hemodialysis, the Gambro® AK-10 (Lund, Sweden) was used at a blood flow
rate of 150-200 mL/min using a capillary filter Nephros
Table 1. The Heparin Response
in Hemodialysis Patients
Patient
Number
Heparin
. (IU/mL)
(Theoretical)
Heparin Measured (U/mL)
TCT
APTT
S-2222
1
2
3
4
5
6
7
8
9
10
0.5
"
"
"
"
"
"
"
"
1.10
1.04
0.80
1.00
2.60
0.53
0.38
0.80
0.52
0.52
0.50
0.53
0.21
0.35
(>5 min)
0.29
0.22
0.45
0.29
0.29
0.54
0.51
0.41
0.48
0.94
0.41
0.48
0.50
0.45
0.40
X(CV)
0.5
0.93
(68.6)
0.35 (33.7)
0.51 (31.0)
Type II F 100 (Organon, Teknika, B.V. Boxtel, The
Netherlands) or a membrane filter Gambro Lundia®
plate 11.5 nm (Lund, Sweden). For hemofiltration, the
Hemofiltration monitor AK-10 (Lund, Sweden) at a
blood flow rate of 350-400 mL/min and the Gambro
hemofilter 202 (Lund, Sweden) were used. Before the
start of hemodialysis, the artificial kidney was washed
through with 1,200 IU heparin in 1 L 0.15 M NaCl; the
washing fluid was drained out while filling the artificial
kidney with blood.
Heparin sodium (Nyegaard & Co, Oslo, Norway),
5,000 and 1,200 IU/mL of porcine mucosal origin, was
used. Protamine sulfate (Novo, Copenhagen, Denmark)
10 mg/mL was used.
A Harvard® pump (Harvard Apparatus Company,
Dover, MA) was used for continuous infusion of heparin
or protamine sulfate.
Vacutainer® blood-collecting vials (Terumo, Tokyo;
Japan) were used for blood collection from the arterial
side of the artificial kidney before the heparin connecting
tube (patient values) and from the venous side (artificial
kidney values). Blood was immediately transferred to
plastic vials on ice. Platelet-poor plasma (PPP) was
obtained by centrifugation of blood at 4 °C (1,000 X g,
20 min).
Vol. 84 • No. 3
HEPARINIZATION DURING HEMODIALYSIS
319
Heparin (U/ml]
pHN-S-2222
Heparin (U/ml]
pHN-S-2222
2.0
2.0
1.0
1.0
60
120
180
240
300
60
180
min
120
min
Hemodialysis
Hemofiltration
FlG. 2. Total heparinization. A bolus injection of 8,400 1U followed by | ,200 lU/hour was used. The heparin concentrations
(•
•) were equal in the artificial kidney and in the patient.
Heparinization
Methods
Total Heparinization. A bolus dose of 8,400 IU
heparin was given independent of the body weight (w)
at the start of hemodialysis or hemofiltration, followed
by continuous infusion of 20 IU heparin/min.
High-Dose Regional Heparinization and Neutralization. The regional flow of heparin (X mL/hour of 1,200
U/mL) required to obtain 1 U heparin/mL plasma at a
blood flow rate of F (mL/min), was calculated:
X = F(1 - PCV)5/10 2
Heparin (U/ml)
0.10
0.5 V
Low-Dose Regional Heparinization. The regional flow
of heparin was initially 50 IU/min, but was later standardized to 25 IU/min (5 mL/hour of 300 lU heparin/
mL) for hemodialysis as well as for hemofiltration.
Low-Dose Regional Heparinization and Neutralization. The low-dose regional heparinization method (C)
was used. Neutralization of heparin (25 IU/min) was
done by 0.25% (2.5 mg/mL) protamine sulfate (Z mL/
hour):
Z = 25 X 60 X 7.63/2.5 X 103 = 4.6 mL/hour
Dialysis 3
0.5 -
The corresponding flow of 1% (10 mg/mL) protamine
sulfate (Y mL/hour) required for heparin neutralization,
was calculated:
Y = h 60 X 7.63/104 = F(l - PCV) 4.6/10 2
°
0.0
1 l N
4!-
•-•—•—/
\
§l/
O
0.5'
1
Dialysis 2
Dialysis 1
«*>012
•0.10
^•-.05&O
(O?;/.•&'
o-o-o —
1
5 Hours
FIG. 3. High-dose regional heparinization and neutralization. Heparin
concentrations of the artificial kidney (•
•) and the patient
(O
O) are presented. The heparin flow (mL/min of 1,200 IU/
mL) is marked above curves, and theflowof protamine sulfate (mL/
min of 10 mg/mL) below curves; in patient 3, there was a short stop
of the heparin flow.
320
TALSTAD AND KJELBY
A.J.C.P. • September 1985
Blood flow
(ml/min)
Heparin
(U/ml)
1.0-
©
0.5
^
^
150
0
©
0.5
150
Blood flow
(ml/mm)
200
200
200
60
120
180
240 min
Hemodialysis
60
120
180
mm
Hemofiltration
FIG. 4. Low-dose regional heparinization. Heparin concentrations of the artificial kidney (•
•) and of the patient (O
are shown. The heparinflow(lU/min) is marked above curves. In patient 4, there was a short stop of heparin flow.
Heparin Assays
Heparin monitoring during hemodialysis was done in
whole blood;16 exact measurements were done in PPP.
The Thrombin Clotting Time (TCT). Topostasine
(Hoffmann-La Roche, Basel, Switzerland) containing
3,000 NIH IU thrombin/vial, was diluted with 0.15 M
NaCl to 20 and 30 NIH IU/mL (T 20 and T 30 , respectively). PPP (0.2 mL) was incubated at 37 °C for 3
O)
minutes, after which the thrombin reagent (0.1 mL) was
added and the clotting time measured.
The Activated Partial Thromboplastin Time (APTT).
Cephotest (Nyegaard & Co. Oslo, Norway) (0.1 mL)
was mixed with PPP (0.1 mL), incubated at 37 °C for
6 minutes, after which 0.1 mL 0.020 M CaCl2 was added
and the clotting time measured. The heparin concentrations for the TCT and APTT assays were read from
standard curves.16
HEPARINIZATION DURING HEMODIALYSIS
Vol. 84 . No. 3
The S-2222 assay was done by the Coatest heparin
(Kabi, Stockholm, Sweden). The partial heparin neutralization (pHN)-assays15 were used at high heparin
concentrations (>1.0 IU/mL).
321
Heparin
(U/ml)
Blood flow
(ml/min)
'.0i
400
Results
Heparin Assaying
The in vitro recovery of 0.5 IU heparin/mL plasma
from ten hemodialysis patients, was measured. The
accuracy and precision were in favor of the S-2222 assay
compared with the TCT (T30) and APTT assays (Table 1).
Heparin Kinetics during Heparinization
350
Methods
Total heparinization was done in seven patients with
hemodialysis and four patients with hemofiltration (Fig.
2). The initial heparin-concentrations were 1.4-2.4 (predicted, 1.9-3.5) IU/mL in the artificial kidney and the
patient; the slope of curves differed between patients.
High-dose regional heparinization and neutralization
was performed in three patients (Fig. 3). Sustained
heparin-concentrations between 0.25-0.60 IU/mL were
obtained in the artificial kidney, and <0.10 IU/mL in
the patient. In patient 3 there was a short accidental
stop of heparin flow.
Low-dose regional heparinization was studied in five
patients during hemodialysis and in three patients during
hemofiltration (Fig. 4). The initial heparin concentrations
at heparin flow 25 IU/min were 0.25-0.45 (predicted,
0.09-0.18) IU/mL in the artificial kidney. Patients 3, 4,
6, 7, and 8 showed increasing slopes resulting from an
accumulation of heparin in the patient; in patient 4,
there was an accidental stop of heparin flow.
Low-dose regional heparinization and neutralization
was studied in two patients during hemodialysis and in
three patients during hemofiltration (Fig. 5). The heparin
concentrations at heparin flow 25 IU/min ranged between 0.1-0.35 (predicted, 0.09-0.18) IU/mL in the
artificial kidney, and <0.15 IU/mL in the patient. The
neutralization of heparin was not complete, and explains
the slightly increasing slopes at heparin flow 35 IU/min.
Discussion
Various methods of heparinization during hemodialysis were analyzed by heparin kinetics. Heparin measurements in hemodialysis patients were greatly influenced by the different sensitivities for heparin.1 This
study indicated that the S-2222 assay showed greater
accuracy and precision than the TCT or APTT assays
in these patients. The pHN-assays are preferable at high
heparin concentrations. 15
300
200
-I
1
x>
o
e
0.5200
k
J
2 5
60
120
180
240 (min)
FIG. 5. Low-dose regional heparinization and neutralization. Heparin
concentrations of the artificial kidney (•
•) and of the patient
(O
O) are shown. The heparin flow (IU/min) is marked above
the curves, and heparin (IU/min) neutralized by protamine sulfate (2.5
mg/mL), below curves.
The total heparinization method exceeded the accepted
therapeutic ranges. Only the initial heparin concentrations could be predicted; the different slopes of the
curves result from different distribution volumes and
clearance rates of heparin. 1718 This method, as well as
the intermittent heparinization methods, 8 ' 91319,20,22 cause
equal heparinization of the artificial kidney and the
patient—a not ideal principle in high-risk patients. The
heparinization may be reduced by repeated heparin
monitoring, 7.10.21 but the complications are fewer by
continuous than by intermittent therapy.12
322
TALSTAD AND KJELBY
A.J.C.P. •September 1985
2. Bjornson J, Kierulf P, Eika C, Godal HC: Fibrin deposits in the
The high-dose regional heparinization and neutralizaKiil dialyser. Scand J Haematol 1973; 11:379-382
tion method showed satisfactory heparin concentrations
3. Bjornson J, Godal HC: Impaired anticoagulant effect of heparin
in the artificial kidney, and negligible heparin in the
in the artificial kidney. Scand J Clin Lab Invest 1976; 36:581589
patient. However, the method had the least compliance
4.
Cullmann
W, Glockner WM, Miiller N: Heparin-Wirkung bei
of all the methods studied, i.e., if anything happened
uramischen Patienten wahrend der Hamodialyse. Fortschr Med
that interfered with the heparin or protamine flow, a
1981;99:410-412
5. Ghezzi PM, di Siena F, Palanca R, Dutto A, Cento G: Cinetica
rapid rise or drop of heparin might occur. The highdell anticoagulazione in emodialisi. Minerva Med 1980; 71:
dose regional heparinization method was 10 times more
2987-2991
expensive than the low-dose regional heparinization
6. Gordon LA, Simon ER, Rukes JM, Richards V, Perkins HA:
Studies in regional heparinization. II Artificial-kidney hemodimethod.
alysis without systemic heparinization—Preliminary report of
The low-dose regional heparinization method maina method using simultaneous infusion of heparin and protamine.
tained satisfactory heparinization of the artificial kidney
N Engl J Med 1956; 255:1063-1066
7. Gotch FA, Keen ML: Precise control of minimal heparinization
at a low flow of heparin (25 IU/min). The heparin
for high bleeding risk hemodialysis. Trans Am Soc Artif Int
concentrations in the patient gradually increased until
Organs 1977; 23:168-176
an equilibrium was obtained, depending on the heparin
8. Kjellstrand C-M, Buselmeier TJ: A simple method for anticoagulation during pre- and postoperative hemodialysis, avoiding
flow, distribution volume, and clearance of heparin.
rebound phenomenon. Surgery 1972; 72:630-633
The low-dose regional heparinization and neutraliza9. Kovac A, Hiinicke G, Bierwisch H: Ehrfahrungen mit der minimaltion method was evaluated as a consequence of this
intermittierenden Heparinisierung bei chronischen Dialysepatienten. Z Urol Nephrol 1980; 73:353-359
study. A constant heparinization of the artificial kidney
10. Lopot F: Heparin kinetics and methods of heparinization during
was obtained as for the low-dose regional heparinization
haemodialysis. Cas Lek Cesk 1980; 119:139-144
method, and there was less accumulation of heparin. A
11. Penner JA: Experience with a thrombin clotting time assay for
measuring heparin activity. Am J Clin Pathol 1974; 61:645satisfactory balance between heparinization and neu653
tralization can be obtained at any step between high12. Salzman EW, Deykin D, Shapiro RM, Rosenberg R: Management
dose and low-dose regional heparinization by using the
of heparin therapy. Controlled prospective trial. N Engl J Med
1975;292:1046-1050
same infusion rates of heparin (1,200 IU/mL) and
13. Shapiro WB, Faubert PF, Porush JG, Chou S-Y: Low-dose heparin
protamine sulfate (10 mg/mL), or of equal dilutions of
in routine hemodialysis monitored by activated partial thromthese solutions. The low-dose regional heparinization
boplastin time. Artif Organ 1979; 3:73-77
14. Swartz RD, Port FK: Preventing hemorrhage in high-risk hemoand neutralization method using 25 IU heparin/min
dialysis: Regional versus low-dose heparin. Kidney Int 1979;
seemed satisfactory for hemodialysis as well as for
16:513-518
hemofiltration, obviously because less heparin is needed
15. Talstad 1: A new principle in heparin assaying based on partial
neutralization of heparin with polybrene. Thromb Res 1980;
at high blood flow rates. This method approaches the
18:485-491
ideal method of heparinization not requiring heparin
16. Talstad I: Problems by using whole blood in heparin measurements.
monitoring since heparin-concentrations were not influThromb Haemost 1982; 47:177-181
17. Talstad I: Heparin adjusted for body weight. Am J Clin Pathol
enced by different body weight or clearance of heparin.
1985; 83:378-381
So far we have used this method (5 mL/hour of 300 IU
18. Teien A, Bjornson J: Heparin elimination in uraemic patients on
heparin/mL and 5 mL/hour of 2.5 mg/mL protamine
haemo-dialysis. Scand J Haematol 1976; 17:29-35
19. Vogel GE, Kopp KF: The conflict between anticoagulation and
sulfate) in 50 high-risk patients during hemodialysis or
hemostasis during hemodialysis. Int J Artif Organs 1978; 1:
hemofiltration without clotting of their artificial kidneys
181-186
and without untoward bleeding problems. The method
20. Vogel GE: Hamodialyse ohne Blutungsrisiko. Einfuhrung einer
APTT-Bedside-Methode zur exakten Heparin-Monitorisierung—
is a simple standardized method that can be used
Ein Uberblick. Fortsch Med 1977; 95:2437-2444
routinely, and with which long-term complications of
21. Ward RA, Farrel PC: Precise anticoagulation for routine hemodiheparin therapy (osteoporosis) might be avoided.
alysis using nomograms. Trans Am Soc Artif Int Organs 1978;
24:439-442 .
Acknowledgment. The technical assistance of Agnes Aadnesen is
22. Willimann P, Alig A, Binswanger U: Minimal intermittent hepagratefully acknowledged.
rinization during hemodialysis. Nephron 1979; 23:191-193
23.
Woods
HF, Weston MJ, Bunting S: Haemodialysis without heparin.
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