ASTM F1841-97
(Practice)Standard Practice for Assessment of Hemolysis in Continuous Flow Blood Pumps
Standard Practice for Assessment of Hemolysis in Continuous Flow Blood Pumps
SCOPE
1.1 This recommended practice covers a protocol for the assessment of the hemolytic properties of continuous flow blood pumps used in extracorporeal or implantable circulatory assist. An assessment is made based on the pump's effects on the erythrocytes over a certain period of time. For this assessment, a recirculation test is performed with a pump for 6h.
1.2 The values stated in both inch-pound and SI units are to be regarded as the standard. The SI units given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:F1841–97
Standard Practice for
Assessment of Hemolysis in Continuous Flow Blood
Pumps
This standard is issued under the fixed designation F 1841; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The goal of blood pump development is to replace or supplement the function of the human heart.
As a result, continuous flow blood pumps, including roller pumps and centrifugal pumps, are
commonly used in clinical extracorporeal circulation. They are used not only for cardiopulmonary
bypass in routine cardiac surgery but also for ventricular assist, percutaneous cardiopulmonary
support, and extracorporeal membrane oxygenation.
Many investigators have attempted to develop an atraumatic blood pump. Hemolysis is one of the
most important parameters of blood trauma induced by blood pumps. However, comparative in vitro
evaluation of the reported results of hemolysis are difficult due to the lack of uniformity of the test
methods employed. Thus, it is necessary to standardize the method of performing in vitro hemolysis
tests for the evaluation of continuous flow blood pumps.
1. Scope 3.1.1 continuous flow blood pump—a blood pump that
produces continuous blood flow due to its rotary motion.
1.1 This recommended practice covers a protocol for the
3.1.2 free plasma hemoglobin—the amount of hemoglobin
assessment of the hemolytic properties of continuous flow
(iron or heme-containing protein) in plasma.
blood pumps used in extracorporeal or implantable circulatory
3.1.3 hemolysis—damage to erythrocytes resulting in the
assist. An assessment is made based on the pump’s effects on
liberation of hemoglobin into the plasma.
the erythrocytes over a certain period of time. For this
3.1.4 Index of Hemolysis
assessment, a recirculation test is performed with a pump for 6
3.1.4.1 normalized index of hemolysis—added grams of
h.
plasma free hemoglobin per 100 l of blood pumped, corrected
1.2 The values stated in both inch - pound and SI units are
for plasma volume using hematocrit and normalized by flow
to be regarded as the standard. The SI units given in parenthe-
rate and circulation time.
ses are for information only.
3.1.4.2 normalized milligram index of hemolysis— normal-
1.3 This standard does not purport to address all of the
ized index of hemolysis expressed by milligram value of free
safety concerns, if any, associated with its use. It is the
plasma hemoglobin.
responsibility of the user of this standard to establish appro-
3.1.4.3 modified index of hemolysis—mass of hemoglobin
priate safety and health practices and determine the applica-
released into plasma normalized by the total amount of
bility of regulatory limitations prior to use.
hemoglobin pumped through the loop.
2. Referenced Documents
4. Formulas
2.1 ASTM Standards:
4.1 Normalized Index of Hemolysis (N.I.H.) (1,2,3,4) :
F 1830 Practice for Selection of Blood for In Vitro Evalu-
ation of Blood Pumps 100 – Ht 100
N.I.H. g/100l5DfreeHb 3 V 3 3 (1)
100 Q 3 T
3. Terminology
3.1 Definitions:
Dfree Hb = increase of plasma free hemoglobin concentra-
tion (g/L) over the sampling time interval,
This practice is under the jurisdiction ofASTM Committee F-4 on Medical and
Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.30 on Cardiovascular Standards.
Current edition approved Dec.10, 1997. Published June 1998. The boldface numbers given in parentheses refer to a list of references at the
Annual Book of ASTM Standards, Vol 13.01. end of the text.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1841
port. The primed blood volume is 450 6 45 mL. A screw
where:
clamp,thatispositionedattheoutletside,isappliedtoproduce
V = circuit volume (L),
Q = flow rate (L/min), the required conditions for the left heart assist application (5
Ht = hematocrit (%), and
L/min against 100 mm Hg pressure head (that is, with the
T = sampling time interval (min).
pressure sampling ports at the same vertical height, the
4.2 Normalized Milligram Index of Hemolysis. (mg.N.I.H.)
pressure in the outlet line of the pump is 100 mm Hg greater
(2,3,4):
than in the inlet line)) and for the cardiopulmonary bypass
100 – Ht 100 application (5 L/min against 500 mm Hg pressure head).
2mg.N.I.H.mg/100l5DfreeHb 3 V 3 3 (2)
100 Q 3 T
(Optional testing at 350 or 700 mm Hg is also advisable.) To
monitor such pressure heads, the pressure monitoring lines are
4.3 Modified Index of Hemolysis (M.I.H.):
incorporated into the test loop both at the inlet and outlet tubes.
4.3.1 Modifiedindexofhemolysis(M.I.H.)(5,6)thatcanbe
An ultrasonic or electromagnetic flow probe is placed at the
written with no units or as (milligram of hemoglobin released
outlet side of the pump between the clamp and the reservoir to
into plasma/mg of total hemoglobin pumped through the loop):
monitor the flow rate. A thermistor is connected to the loop,
100 – Ht 10
M.I.H.5DfreeHb3 V 3 3 (3) and the blood temperature is measured using a corresponding
100 Q 3 T 3 Hb
thermometer.
where:
5.3 Pump Conditions— Pump flow rate is set at 5 6 0.25
Hb = total blood hemoglobin concentration at time
L/min at the circulating blood temperature of 37 6 1°C. The
zero (mg/L), and
total pressure head is set at 100 6 3 mm Hg for the left heart
Dfree Hb = increase of plasma free hemoglobin concentra-
assist application and 500 6 15 mm Hg for cardiopulmonary
tion (mg/L) over the sampling time interval.
bypass application. However, additional testing temperatures
4.3.2 Among these indices, M.I.H. is recommended as an
canbechosenfrom0to42°Caccordingtotheintendedclinical
index to express the degree of hemolysis caused by a blood
use of the pump (for example, cardiopulmonary bypass may
pumpinarecirculatingsystem.N.I.H.wasproposedtoaccount
include cooling and warming during surgery.)
for the plasma volume based on the hemotocrit. Recent
5.4 Evaluation—The free plasma hemoglobin is determined
development of less hemolytic blood pumps has since made it
by a clinically approved assay method (see 9.3). The free
convenient to use mg. N.I.H. rather than N.I.H. However, both
plasma hemoglobin is standardized by calculating the M.I.H.
the N.I.H. and the mg N.I.H. vary with hematocrit of the blood
(6). M.I.H. is the recommended index to express the degree of
6. Significance and Use
hemolysis caused by a blood pump in a recirculating system.
The M.I.H. equation corrects for differences in blood hemo-
6.1 The objective of this practice is to standardize the
globin concentration and hematocrit directly (5).
evaluation method for detecting the hemolytic effect of a
4.4 Testing Blood— Because the level of trauma-induced
continuous flow blood pump used in extracorporeal circulation
hemolysis is different based on the source of blood, it is
and circulatory assistance.
necessary to identify the source of blood and its respective
index of hemolysis. Human, bovine, or porcine blood are
7. Preparation of Hemolysis Test
recommended as the primary sources of testing blood (see
7.1 Blood—The blood is obtained from human volunteers
Practice F 1830). It is preferable that the blood collected at a
having normal body temperature, exhibiting no physical signs
standard slaughter house not be used due to the risk of being
of disease and having hematological profiles in the normal
contaminated with fluids other than blood, unless the blood is
acceptable range. (Donors are subjected to standard blood
obtained by controlled venipuncture.Although animal blood is
used in the development stage of a pump, it is suggested that donor screening procedures.) The donor should be fasted for 8
h or more to avoid additional hemolysis due to a high
pre-clinical evaluation tests be repeated with human blood.
concentration of lipids in the blood.The delay in the collection
5. Summary of Practice of the blood and the hemolysis test should not exceed 48 h of
refrigerated storage with the blood temperature kept between 2
5.1 Blood—The blood is obtained from human volunteers,
and 8° C or more than2hat ambient condition. As an
cattle or pigs having normal body temperatures, no physical
alternative source of blood, animal blood can be used, but it is
signs of disease, including diarrhea or rhinorrhea, and an
necessary that the source of blood is identified. The preferred
acceptable range of hemotological profiles. The blood should
animal blood is bovine and porcine (See Practice F 1830).
be collected by vascular puncture using a needle (14G or
Since the use of completely fasted animals is impractical, it is
larger) and collected into the standard 500–2000 mL bags
recommended that the animals be subjected to a 12-h fasting.
containing citrate phospate dextrose adenine (CPDA-1) anti-
As a quality control measure, any blood having free plasma
coagulant solution (See Appendix X2) or heparin sulfate (See
hemoglobin of more than 20 mg/dLshould not be used for this
Appendix X3). The blood from a slaughterhouse can typically
be used if it is obtained by controlled venipuncture. test. In order to standardize the blood trauma testing, the blood
5.2 Test Loop (4) (See Fig. 1)—The test loop consists of a subjected to the test should have the hematocrit value adjusted
to be within the range 30 6 2% by hemodilution (with
total of 6.6 ft (2 m) of 3/8 in. (9.5 mm) ID polyvinylchloride
tubing and a
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