Hemolysis in Different Centrifugal Pumps

Abstract: Different types of centrifugal pumps cause different amounts of hemolysis based on shear stress and blood exposure time. However, the hemolytic characteristics of centrifugal pumps in each clinical condition are not always clear. We compared the hemolytic characteristics of one cone-type centrifugal pump (Medtronic Bio-Medicus BP-80) and 2 impeller-type centrifugal pumps (Nikkiso HMS-12 and Terumo Capiox) under experimental conditions simulating their use in cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and percutaneous cardiopulmonary support (PCPS) as well as their use as left ventricular assist devices (LVADs). The normalized indexes of hemolysis (NIHs; grams free plasma hemoglobin per 100 L blood pumped) during use as LVADs were not significantly different among the 3 pumps. The BP-80 pump produced almost 3–fold more hemolysis than the HMS-12 and Capiox pumps during CPB, 3– to 4–fold more hemolysis during ECMO, and 5.5–fold more hemolysis during PCPS. The 2 impeller-type centrifugal pumps will therefore cause less hemolysis under high flow, high pressure difference (as in CPB) and low flow, high pressure difference (as in ECMO and PCPS) conditions than the cone-type pump.     

Less Blood Damage in the Impeller Centrifugal Pump: A Comparative Study with the Roller Pump in Open Heart Surgery

Abstract: A centrifugal pump with an impeller (Nikkiso Centrifugal Pump, Model HPM15; Nikkiso Co. Ltd.) was applied to cardiopulmonary bypass (CPB) in 14 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin level, platelet count, and serum p-thromboglobulin (pTG) level were measured during CPB. The results were compared with those obtained in a comparative roller pump (RP) group (n = 10). There was no difference in the time on CPB between the NP (109 min) and RP (121 min) groups. The serum pTG level (ng/ ml) was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB). The plasma-free hemoglobin level also was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB, 120 min after the initiation of CPB, immediately after the termination of CPB, 3 h after termination of CPB; p < 0.01). There was no significant difference in platelet depletion. The HPM15 pump showed excellent hemodynamic performance with less blood trauma compared with the roller pump in its clinical application to open heart surgery.     

Cardiopulmonary Bypass with Nikkiso and BioMedicus Centrifugal Pumps

Abstract: In our department, a new compact and atraumatic centrifugal pump, Nikkiso, was developed as a second-generation cardiopulmonary bypass pump. To assess and confirm the function and controllability of this pump, comparative studies of cardiopulmonary bypass with Nikkiso and BioMedicus centrifugal pumps were performed using calves. Both pumps provided pump flows of 60–70 ml/kg/min without incidence. The hemodynamics of both groups were stable and within the normal range, and no leakage or thrombus formations were observed in either pump. All hematology and biochemistry data showed no significant differences between the two groups. Plasma free hemoglobin values of the Nikkiso pump tended to be lower than those of the BioMedicus pump. The Nikkiso pump was easy to handle because of its smaller size, and air removal was easily performed because of its low priming volume. The Nikkiso pump demonstrated easy manipulation and good controllability. This compact, atraumatic centrifugal pump meets the requirements for a second-generation cardiopulmonary by-pass pump.     

Clinical Comparative Study of Cardiopulmonary Bypass with Nikkiso and BioMedicus Centrifugal Pumps

Abstract: The Nikkiso centrifugal pump was evaluated in elective adult open heard surgery in comparison with the BioMedicus pump. Ten patients using the Nikkiso pump (Group N), and 10 patients using the BioMedicus pump (Group B) were examined for (or to determine) hemato-biologic parameters and patient outcome data as well as pump controllability. During cardiopulmonary bypass (CPB), both pumps maintained systemic perfusion satisfactorily without any mechanical adverse event. Rotation speed of the Nikkiso centrifugal pump (3,580 ± 100 rpm) was significantly higher than that of the BioMedicus pump (3,170 ± 100 rpm; p < 0.05) whereas changes in free plasma hemoglobin, platelet count, blood urea nitrogen, and creatinine levels showed no significant differences between the two groups. Urine output in Group N for 30 min after the initiation of CPB (7.10 ± 1.50 ml/kg/h) was significantly higher than that in Group B (3.23 ± 0.46 ml/kg/h; p < 0.05). Patient outcome data were similar in both groups, such as duration of intensive care unit stay, hospital stay, postoperative intubation time, amount of postoperative bleeding, and amount of blood transfused. These equivalent results with the BioMedicus pump suggested that the Nikkiso pump can be used in open heart surgery as a reliable and atraumatic CPB pump.     

Clinical Experience with Nikkiso Centrifugal Pumps for Extracorporeal Circulation

Abstract: A comparative study of a newly developed impeller–type centrifugal pump, Nikkiso HMS–15, was made to assess the effects on hemolysis, platelet function, and renal function for extracorporeal circulation (ECC) during open heart surgery. The Bio–pump (cone–type, Medtronic) and the roller pump were used as controls. The increase of serum hemoglobin level in the Nikkdiso pump was significantly lower than that in the other pumps. The decrease of platelet counts was recognized after the initiation of ECC in the three pumps whereas the levels of platelet factor 4 and β–thromboglobulin in the Nikkiso pump group increased by far less than in the other two groups. Moreover, renal function was better maintained in the Nikkiso pump group; in particular, a significantly higher urine output was recorded during ECC and for 1 h after the termination of ECC. The results of our clinical studies suggest that the Nikkiso centrifugal pump is suitable for ECC during open heart surgery.     

Clinical Evaluation of the Centrifugal Pump in Open Heart Surgery: A Comparative Study of Different Pumps

Abstract: The centrifugal pump is now widely used in open heart surgery for its clinical benefits related to the blood elements and the coagulation system. The purpose of this study was to compare the clinical performances of and the outcomes offered by 4 types of centrifugal pumps. For each pump, we investigated the effects on the blood elements, coagulation system, complements, and immunoglobulins during open heart surgery. Four types of centrifugal pumps were used: the HPM-15 (Nikkiso Co.), the Capiox (Terumo Co.), the Lifestream (St. Jude Medical Co.), and the BP-80 (Medtronic, BioMedicus Co.). The platelet count, lactate dehydrogenase (LDH), antithrombin III (AT III), thrombin-antithrombin complex (TAT), complements (C3, C4, and CH₅₀), and immunoglobulins (IgG, IgA, and IgM) were measured before and after cardiopulmonary bypass (CPB). The platelet count was decreased more significantly by the HPM-15 than by any of the other pumps. The other parameters showed no difference among the 4 pumps. In clinical use, each of the 4 types of centrifugal pumps was safe.     

Percutaneous cardiopulmonary support with heparin-coated circuits in postcardiotomy cardiogenic shock. Efficacy and comparison with left heart bypass.

OBJECTIVE: Percutaneous cardiopulmonary support, a simplified form of venoarterial bypass, using totally heparin-coated circuits, has recently come into clinical use. To clarify its efficacy in postcardiotomy cardiogenic shock to aid weaning from cardiopulmonary bypass, we compared results of percutaneous cardiopulmonary support with those of left heart bypass using a centrifugal pump. METHODS: We reviewed 18 patients treated between 1991 and 1998 who could not be weaned from cardiopulmonary bypass. Nine were aided by totally heparin-coated percutaneous cardiopulmonary support (PCPS group), and 9 supported by left heart bypass using a centrifugal pump (LHB group). In both groups, activated clotting time was controlled at 150-200 seconds using minimal doses of heparin as needed. RESULTS: Weaning and survival rates were higher in the PCPS group than in the LHB group (100% vs 55.6%, and 66.7% vs 22.2%). The PCPS group had a smaller amount of blood loss and needed a smaller amount of blood components in the immediate postoperative period. One percutaneous cardiopulmonary support patient required surgical re-exploration for postoperative bleeding (11.1%), but no clinical thromboembolic event occurred in the PCPS group. In the LHB group, 5 patients underwent surgical re-exploration for postoperative bleeding (55.6%), and 2 underwent thrombus extirpation in the left ventricle (22.2%). CONCLUSIONS: Although this study was retrospective and historical backgrounds could have been involved, our data suggest that totally heparin-coated percutaneous cardiopulmonary support system appears more effective as an aid to weaning from cardiopulmonary bypass and in short-term circulatory support for patients in postcardiotomy cardiogenic shock.     

Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass

The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.     

Hematologic and endocrinologic effects of pulsatile cardiopulmonary bypass using a centrifugal pump]

The effects of pulsatile and nonpulsatile flow during cardiopulmonary bypass (CPB) with of centrifugal pump (Sarns) and membrane oxygenator, on blood cells, hemodynamics, and hormonal response were studied. In the pulsatile group (group P) in which pulsatile flow was generated by centrifugal pump and a 20 Fr arterial cannula was used, hemolysis and reduction of platelet count during CPB were more marked than in the nonpulsatile group (group NP), in which the same type of circuit was used. When the 20 Fr arterial cannula was replaced with a 24 Fr cannula (group Pc), the rate of hemolysis during CPB was significantly reduced compared with that in group P (p less than 0.05). The rate of rise in plasma free hemoglobin from 10 to 70 minutes CPB in group Pc was 15.0 mg/dl/hr, this value did not exceed that in either group NP or in group Pr, in which a roller pump rather than centrifugal pump was used to generate pulsatile flow. These findings show that pulsatile CPB with a centrifugal pump produces no deleterious hematologic effect in clinical use. The rise in the level of angiotensin II in group P was significantly smaller than that in group NP (p less than 0.05), and the rise in plasma renin activity and levels of angiotensin I, adrenalin and noradrenaline were smaller than those in group NP, although these differences were no significance. These findings indicate that the centrifugal pump generates pulsatile flow effectively, although not so effectively as to prevent the rise in peripheral vascular resistance. During CPB, there was no change in levels of thyroid hormones, including free T3, free T4 and reverse T3, in either pulsatile groups P and Pc or nonpulsatile group. TSH level in group Pc was significantly elevated in contrast with that in the nonpulsatile group (p less than 0.05), in which no change in TSH level was seen. It is suggested that pulsatile perfusion using a centrifugal pump might maintain sufficient hypothalamic-pituitary function to permit secretion of TSH in response to various stimuli.     

The Hemolysis Test of the Gyro C1E3 Pump in Pulsatile Mode

Abstract: While a centrifugal pump is generally used for nonpulsatile blood flow, it can also produce a pulsatile flow by alternating the impeller rotational speed (rpm) periodically. However, there is concern that this centrifugal pump pulsatile mode may induce added hemolysis as a result of the repeated acceleration and deceleration of rpm. Thus, a hemolysis study of the pulsatile modes of the Gyro C1E3 centrifugal pump (Gyro-P) was conducted. The results were then compared with the nonpulsatile mode of the same Gyro pump (Gyro-N) and the nonpulsatile BioMedicus BP-80 (Bio-N) pump. Three different conditions were simulated: left ventricular assist device (LVAD), cardiopulmonary bypass (CPB), and percutaneous cardiopulmonary support (PCPS). The beating rate of the Gyro-P was set at 40 bpm, with repetition of 2 different impeller speeds (the lower rpm being 70% of the higher speed). The 2 impeller speeds were set to obtain the same average flow as that of the nonpulsatile mode. The hemolysis results of the Gyro-P were comparable to or better than those of the Bio-N, and no excessive hemolysis was observed, compared to the Gyro-N. In conclusion, the Gyro-P had an excellent hemolytic characteristic and generated no excessive hemolysis in most clinical usage conditions. With the concern of hemolysis eliminated, this pulsatile mode may have various possible advantages.     

Clinical Experiences of Percutaneous Cardiopulmonary Support: Its Effectiveness and Limit

In recent years, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB) and postcardiotomy cardiac support. From April 1990 to March 1997, a percutaneous cardiopulmonary support (PCPS) system was used in 20 patients with an average age of 58 years (13 males and 7 females). They comprised 11 ischemic, 6 valvular, 2 aortic, and 1 congenital heart disease patients. Our PCPS system consists of a centrifugal pump (BioMedicus BP-80), an oxygenator, and a reservoir. The entire blood contacting surface, including that of the thin wall cannulas, is coated by heparin bonded materials. As a result of this new technology, this system can be used for the long term without systemic heparinization. No major critical thrombi were revealed inside the pumps or circuits. Of the 20 patients, 7 (35%) (Group 1) could be weaned from PCPS, and the remaining 13 (Group 2) could not. In Group 1 although 2 patients suffered from renal failure and pneumonia, respectively, both were discharged from our hospital. The long-term survival rate was 35%. In Group 2 cerebral vascular damage was recognized in 3 patients, renal failure in 4, multiple system organ failure in 4, bleeding in 2, arrhythmia in 1, and leg ischemia in 2. Pulse pressure was significantly elevated due to the recovery of the native heart in Group 1, 2 days after support. However, in Group 2, it did not elevate, and the left ventricular ejection fraction was less than 30 %, associated with high left atrial pressure. In conclusion, this heparin coated PCPS system was very simple and easy to control. It demonstrated long-term biocompatibility and was very effective in recovering deteriorated cardiac function. Quicker application of this system can play an important role in preventing severe complications and obtaining better clinical results. If long-term support is necessary, a ventricular assist device (VAD), which is more powerful, durable, and biocompatible, has to be applied instead of PCPS.     

Development of the Terumo Capiox Centrifugal Pump and Its Clinical Application to Open Heart Surgery: A Comparative Study with the Roller Pump

Abstract: We have developed the Terumo Capiox centrifugal pump (CXP), which consists of a rotor having a unique straight-path design to reduce pump rotational speed without decreasing hydraulic efficiency. The CXP was tested in vitro for blood trauma with a specially designed test circuit using fresh bovine blood. The Biopump (BP) (Medtronic, Minneapolis, MN, U.S.A.) and the roller pump (RP) were used as controls. The CXP demonstrated the smallest elevation of free plasma hemoglobin compared with the BP and the RP. The CXP was then applied to cardiopulmonary bypass (CPB) in 10 patients (CXP group) who underwent elective coronary artery by-pass grafting (CABG), and the results were compared with those for a comparable roller pump group (RP group). Free plasma hemoglobin level, platelet count, and serum β -thromboglobulin ( β -TG) level were measured during CPB. There were no CXP-related complications nor hemodynamic abnormalities during CPB. The CXP group demonstrated less hemolysis and less platelet depletion than the RP group. Furthermore, the serum β -TG level was significantly lower in the CXP group than in the RP group. The CXP showed excellent hemodynamic performance with less blood trauma both in vitro and in clinical application to open heart surgery. Thus, the CXP has significant potential to be safely applied to CPB for open heart surgery and circulatory support.     

Comparison of the Gyro C1E3 and BioMedicus Centrifugal Pump Performances During Cardiopulmonary Bypass

Abstract: The compact eccentric inlet port (ClE3) centrifugal blood pump was developed as a cardiopulmonary bypass (CPB) pump. The C1E3 pump incorporated a seal-less design with a blood stagnation free structure. The pump impeller was magnetically coupled to the driver magnet in a sealless manner. To develop an atraumatic and antithrombogenic centrifugal pump without a shaft seal junction, a double pivot bearing system was introduced. Recently, a mass production model of the C1E3 was fabricated and evaluated. The ratio of the normalized index of hemolysis (NIH) of the C1E3 was 0.007 g/ 100 L, in comparison to the NIH of the BP-80, 0.018 g/ 100 L, each in a CPB condition of 5 Limin against 325 mm Hg. Both pumps were compared in identical in vitro circuits. To further evaluate the pumps during cardio pulmonary bypass for reliability and function, 6 h of CPB was performed on each of 8 bovines using either the C1E3 or BP-80 centrifugal pump. The BP-80 and C1E3 provided pump flows of 5MO ml/kg/min without incident. The hemodynamics were stable, and the hematology and biochemistry data were within normal ranges. There were no statistically significant differences between the 2 groups. Concerning the plasma free hemoglobin values. a mass production model of the C1E3 pump had the same hemolysis levels as the BP-80. Our preliminary studies reveal that the C1E3 pump is reliable. Also, the C1E3 will satisfy clinical requirements as a cardiopulmonary bypass pump.     

A Miniaturized Centrifugal Pump for Assist Circulation

Abstract: The newly developed Nikkiso HMS–15 is a miniaturized centrifugal pump. It has an impeller diameter of only 50 mm and a priming volume of only 25 ml. A totally new approach was applied to develop this very small pump. The new pump showed comparable hemolysis with pumps twice as big (e. g., the most widely used coneshaped centrifugal pump [index of hemolysis, 0. 005]). This finding refutes the belief that the pump diameter must be sufficiently large in size. Clinical application for cardiac assist was performed for 48 h without any thrombus formation despite low heparin dosage. Also, the pump showed quite favorable blood trauma when applied as a pump for cardiopulmonary bypass during open heart surgery. The compactness, the high controllability, and the system versatility proved to be very effective for clinical application. This pump is considered very reliable for its highly optimized design.     

Development of Design Methods for a Centrifugal Blood Pump with a Fluid Dynamic Approach: Results in Hemolysis Tests

The purpose of this study was to examine the relationship between local flow conditions and the hemolysis level by integrating hemolysis tests, flow visualization, and computational fluid dynamics to establish practical design criteria for centrifugal blood pumps with lower levels of hemolysis. The Nikkiso centrifugal blood pump was used as a standard model, and pumps with different values of 3 geometrical parameters were tested. The studied parameters were the radial gap between the outer edge of the impeller vane and the casing wall, the position of the outlet port, and the discharge angle of the impeller vane. The effect of a narrow radial gap on hemolysis was consistent with no evidence that the outlet port position or the vane discharge angle affected blood trauma in so far as the Nikkiso centrifugal blood pump was concerned. The radial gap should be considered as a design parameter of a centrifugal blood pump to reduce blood trauma.     

Cytokine and Endothelial Damage in Pulsatile and Nonpulsatile Cardiopulmonary Bypass

Recently, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB). However, according to the results of our experimental studies, after cardiogenic shock, pulsatile flow was effective in maintaining the functions and microcirculations of end organs, especially those of the liver and kidney. To estimate the effectiveness of pulsatility during CPB, cytokine and endothelin and other metabolic parameters were measured in clinical pulsatile and nonpulsatile CPB cases. From March to May 1997, CPB was performed in 18 elective cases (14 ischemic and 4 valvular disease). In 9 cases, pulsatile perfusion was achieved by the Jostra HL20, which is a newly developed CPB pump (Group P). A nonpulsatile centrifugal pump was used in 9 patients (Group NP). In both groups, as chemical and metabolic mediators, interleukin-8 (IL-8), endothelin-1 (ET-1), and plasma free hemoglobin were measured before and during CPB, and 0.5, 3, 6, 9, 18 h after weaning from CPB. This pulsatile CPB pump could be very simply and easily controlled and could easily produce pulsatile flow. There were no significant differences in CPB time (CPBT), aortic cross clamp time (ACCT), mean aortic pressure, or pump flow during CPB between the both groups. The ET-1 level of Group P was significantly (p < 0.05) lower than that of Group NP 9 h after CPB weaning. The IL-8 level of Group P also showed a lower value than that of Group NP. As for plasma free hemoglobin, there were no significant differences between the groups. These results suggested that even in conventional CPB, pulsatility was effective to reduce endothelial damage and suppress cytokine activation. It may play a important role in maintaining the functions and microcirculations of end organs during CPB.     

Less Platelet Damage in the Curved Vane Centrifugal Pump: A Comparative Study with the Roller Pump in Open Heart Surgery

Abstract: The centrifugal pump with the curved vane (Lifestream Centrifugal Pump [LCP]) was applied to cardiopulmonary bypass (CPB) in 10 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin levels, platelet counts, and serum β–thromboglogulin (β–TG) levels were measured during CPB. The results were compared with those for a comparative roller pump (RP) group (n = 10). There was no difference in CPB time between LCP (112 ± 22 min) and RP (121 ± 22 min) groups. Serum β–TG levels (ng/ml) were lower in the LCP group than in the RP group (34 ± 9 vs. 101 ± 80, 5 min; 81 ± 33 vs. 236 ± 112, 30 min; 120 ± 53 vs. 314 ± 100, 60 min after initiation of CPB; p < 0. 05). There were no significant differences in hemolysis and platelet depletion. The LCP showed excellent hemodynamic performance with less blood trauma in clinical application to open heart surgery.     

Development of an All-in-One Percutaneous Cardiopulmonary Support System

Abstract: This paper deals with development of an all-inone percutaneous cardiopulmonary support (PCPS) system. In recent years, PCPS has been used for the treatment of acute myocardial infarction. A prototype of a compact all-in-one PCPS system was developed. The system contains a centrifugal pump and an extra-capillary flow-type membrane lung in one body. The system has a priming volume of 250 ml, which allows for PCPS with no additional blood. The in vitro tests and an ex vivo test were conducted. The system produces 1.6–5 L/min of flow in the experiments. The O₂ transfer rate was 310 ml/min, and the CO₂ transfer rate was 300 ml/min at a blood flow rate of 5 L/min. This device is compact, requires less priming volume than a standard system, and is easy-to-handle in the experiments. The system is considered applicable to percutaneous cardiopulmonary support.     

Clinical Experience of Percutaneous Cardiopulmonary Support

Abstract: Recently, percutaneous cardiopulmonary support (PCPS) combined with femoro-femoral bypass without reservoir has become valued because of its quick and easy application. We developed a fully preconnected compact integrated cardiopulmonary bypass (CPB) unit (priming volume of 250 ml) with a blind pore membrane oxygenator (Kuraray Menox) for PCPS. From 1990 to 1995, PCPS was performed in 49 patients of whom 26 were weaned from support. In most cases, we applied this CICU in patients with no active bleeding (22 patients); in patients with active bleeding (n = 13), we used Medtron-ic's heparin-bonded close chest support pack (CCSP). Of these, PCPS was performed uneventfully for 2 h (median) in 8 elective cases; all of these patients were weaned or were switched to a left ventricular assist system (LVAS). In 8 urgent cases, such as those with low cardiac output syndrome, PCPS was performed for 4 days (median), 1 was weaned, and 2 CICU were cases switched to other procedures. In 32 cases of shock, 5 CICU patients were weaned, and 3 of them survived. Eight patients including 5 CICU patients and 1 CCSP patient were switched to operation or LVAS, and 2 CICU patients remain alive. From these data, PCPS has been shown to support the patient's circulation in the acute phase and earn time to switch to operation or LVAS; the quick and easy set-up of the CICU can improve the clinical results. The use of the Medtronic device broadened the indication for PCPS. The CCSP enlarged the indication of PCPS but could not improve the results. To improve the results, a heparin-bonded surface is desired.     

Comparative Hemolysis Study of Clinically Available Centrifugal Pumps

Abstract
Centrifugal pumps have become important devices for cardiopulmonary bypass and circulatory assistance. Five types of centrifugal pumps are clinically available in Japan. To evaluate the blood trauma caused by centrifugal pumps, a comparative hemolysis study was performed under identical conditions. In vitro hemolysis test circuits were constructed to operate the BioMedicus BP-80 (Medtronic, BioMedicus), Sams Delphin (Sarns/3M Healthcare), Isoflow (St. Jude Medical [SJM]), HPM-15 (Nikkiso), and Capiox CX-SP45 (Terumo). The hemolysis test loop consisted of two 1.5 m lengths of polyvinyl chloride tubing with a 3/8 -inch internal diameter, a reservoir with a sampling port, and a pump head. All pumps were set to flow at 6 L/min against the total pressure head of 120 mm Hg. Experiments were conducted simultaneously for 6 h at room temperature (21^oC) with fresh bovine blood. Blood samples for plasma-free hemoglobin testing were taken, and the change in temperature at the pump outlet port was measured during the experiment. The mean pump rotational speeds were 1,570, 1,374, 1,438, 1,944, and 1,296 rpm, and the normalized indexes of hemolysis were 0.00070, 0.00745, 0.00096, 0.00066, 0.00090 g/100 L for the BP-80, Sarns, SJM, Nikkiso, and Terumo pumps, respectively. The change in temperature at the pump outlet port was the least for the Nikkiso pump (1.8^oC) and the most with the SJM pump (3.8^oC). This study showed that there is no relationship between the pump rotational speed (rpm) and the normalized index of hemolysis in 5 types of centrifugal pumps. The pump design and number of impellers could be more notable factors in blood damage.