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.     

An in vitro evaluation of an automatic clamp for use with centrifugal pumps

The risk of air emboli is a concern for all perfusionists. A new clamping device for use with centrifugal pumps is designed to clamp both the arterial and venous lines at the first indication of air or retrograde flow, thereby allowing the perfusionist to evaluate the situation and correct the problem before entraining air into the arterial pump head. After evaluating this device in our lab, we conclude that this new safety device should be added to the heart lung machine by all perfusionists using centrifugal pumps.     

Initial Clinical Experience with the Baylor-Nikkiso Centrifugal Pump

Abstract: Recently, a newly developed centrifugal pump, the Baylor-Nikkiso pump, was approved for clinical use in the United States. This pump is the most compact centrifugal pump with a priming volume of only 25 ml. Although it is small, this pump can provide a flow of 4 L/min against a total pressure head of 300 mm Hg at 3,000 rpm. In vitro and in vivo validation of the Baylor-Nikkiso pump has proved that this pump could effectively reduce blood trauma even under high total head pressure. In addition, 48-h durability tests with biventricular bypass using calves verified the reliability of shaft sealing and anti-thrombogenicity. Clinical trials of the Baylor-Nikkiso pumps have been initiated in our department. This pump provides flows of 60–70 ml/kg/min with stable hemody-namic conditions. No leakage or thrombus formation was observed. The results of the initial clinical experience of the Baylor-Nikkiso pump suggest that it is suitable for cardiopulmonary bypass surgery.     

Centrifugal pumps: description of devices and surgical techniques.

BACKGROUND: Because of simplicity of application, universal access, and low cost, centrifugal pumps are commonly used for short-term mechanical cardiac assist. Indications and techniques for application of this technology continue to evolve. METHODS: The clinical experience with 151 patients undergoing centrifugal mechanical cardiac assist at the University of Missouri-Columbia has been reviewed. We have compared commonly available centrifugal pumping systems in vitro and in vivo for characteristics that might distinguish them. RESULTS: Centrifugal pumps have been found to be well suited for use in surgery on the thoracic aorta, for extracorporeal membrane oxygenation and for postcardiotomy cardiac mechanical assist. Complications associated with centrifugal mechanical assist are predictable and common but potentially can be reduced by improved surgical techniques and anticoagulation strategies. In vitro and in vivo experimentation with available centrifugal pumps reveals nuances characteristic of each of the devices. CONCLUSIONS: All centrifugal pumps presently available are less destructive to blood cellular elements compared with roller pumps. With familiarity, all can function satisfactorily for short-term mechanical assist with no compelling evidence that favors any particular centrifugal pump system clinically available. Centrifugal pumps are ideally suited for left heart bypass during surgery on a thoracic aorta and for short-term application as may be required for postcardiotomy mechanical assist. Centrifugal pump technology should be part of the armamentarium of all cardiothoracic surgeons.     

主动脉内球囊反搏联合离心泵左心辅助治疗严重低心排血量综合征

目的：总结主动脉内球囊反搏(IABP)联合离心泵左心辅助治疗严重低心排血量综合征(LCOS)的经验。方法：2000～2004年,于北京大学第一医院心脏外科行冠状动脉旁路移植(CABG)术后出现严重的LCOS5例,在大量应用血管活性药物治疗无效情况下,应用IABP联合离心泵行左心辅助。离心泵经右上肺静脉和升主动脉插管连接。结果：所有患者血流动力学明显改善,联合辅助4～7d后均顺利脱离离心泵。辅助期间5例均出现了不同程度的血液细胞破坏和急性肾功能不全,其中3例在离心泵撤除后肾功能逐渐恢复正常,痊愈出院;1例死于急性肾功能衰竭;1例死于多脏器功能衰竭。5例均需补充全血或浓缩红细胞,4例需补充血小板。结论：IABP联合离心泵进行左心辅助,能明显改善CABG术后大剂量血管活性药物无效的严重LCOS的血流动力学,副作用为血液细胞破坏和急性肾功能不全。     

History of extracorporeal circulation: the invention and modification of blood pumps

The first roller pump was patented in 1855 by Porter and Bradley and was hand operated. A modification first named "surgical pump", designed and manufactured by E. E. Allen in 1887, was intended for direct blood transfusion. Truax, who also distributed and promoted the Allen pump with one roller, developed the first double roller pump in 1899. In the following decades, several researchers, including Beck, Van Allen, Bayliss and Müller as well as Henry and Jouvelet, refined the apparatus and recommended the use of roller pumps for blood transfusion and other applications. After further modifications made by DeBakey in 1934, and application of this pump in one of the first heart-lung machines constructed by Gibbon, DeBakey's name became inseparably attached to this type of pump. For perfusion experiments, an electrically powered roller pump was first used by Fleisch in 1935. Today, the roller pump is the most frequently used blood pump for cardiopulmonary bypass worldwide, having prevailed against the early pulsatile tube compression pumps and ventricular pumps. In recent years, centrifugal pumps have increasingly competed with roller pumps as systemic blood pumps for cardiopulmonary bypass and have become the preferred arterial pump in a variety of centers. Application of mechanical cardiac assistance has evolved from nonpulsatile roller pump support, followed by an era of pulsatile ventricular pumps to the rediscovery of the nonpulsatile flow mode with modern axial flow pumps.     

Computational modeling of the Food and Drug Administration’s benchmark centrifugal blood pump

In order to simulate hemodynamics within centrifugal blood pumps and to predict pump hemolysis, CFD simulations must be thoroughly validated against experimental data. They must also account for and accurately model the specific working fluid in the pump, whether that is a blood-analog solution to match an experimental PIV study or animal blood in a hemolysis experiment. Therefore, the Food and Drug Administration (FDA) benchmark centrifugal blood pump and its database of experimental PIV and hemolysis data were used to thoroughly validate CFD simulations of the same blood pump. A Newtonian blood model was first used to compare to the PIV data with a blood analog fluid while hemolysis data were compared using a power-law hemolysis model fit to porcine blood data. A viscoelastic blood model was then incorporated into the CFD solver to investigate the importance of modeling blood’s viscoelasticity in centrifugal pumps. The established computational framework, including a dynamic rotating mesh, animal blood-specific fluid properties and hemolysis modeling, and a k-ω SST turbulence model, was shown to more accurately predict pump pressure heads, velocity fields, and hemolysis compared to previously published CFD studies of the FDA centrifugal pump. The CFD simulations were able to match the FDA pressure and hemolysis data for multiple pump operating conditions, with the CFD results being within the standard deviations of the experimental results. While CFD radial velocity profiles between the impeller blades also compared well to the PIV velocity results, more work is still needed to address the large variability among both experimental and computational predictions of velocity in the diffuser outlet jet. Small differences were observed between the Newtonian and viscoelastic blood models in pressure head and hemolysis at the higher flow rate cases (FDA Conditions 4 and 5) but were more significant at lower flow rate and pump impeller speeds (FDA Condition 1). These results suggest that the importance of accounting for blood’s viscoelasticity may be dependent on the specific blood pump operating conditions. This detailed computational framework with improved modeling techniques and an extensive validation procedure will be used in future CFD studies of centrifugal blood pumps to aid in device design and predictions of their biological responses.     

Initial experience with the Nikkiso centrifugal pump during thoracoabdominal aortic aneurysm repair

Purpose: Several centers use atriodistal bypass (ADB) as a protective adjunct against distal ischemia during extensive thoracoabdominal aortic aneurysm (TAAA) repair. Most current ADB circuits use indirect-drive centrifugal pumps. The purpose of this report is to describe our initial clinical experience with the Nikkiso pump, a more compact direct-drive centrifugal pump recently developed at Baylor, for ADB during TAAA repair. Methods: The Nikkiso pump was used for ADB perfusion in 10 consecutive patients during graft repair of TAAAs (six Crawford extent I and four extent II). Two patients had aortic dissection. In the four patients who had extent II repairs, selective renal and visceral perfusion was also performed with the Nikkiso pump. Results: No mechanical pump malfunctions or adverse events related to the device occurred. All 10 patients survived and were discharged from the hospital. No patient had paraplegia after surgery. Two patients had delayed lower extremity weakness after undergoing extent I repairs; both recovered and were ambulating at the time of discharge. No complications were associated with bleeding or cerebral, respiratory, renal, or hepatic function. Conclusions: Our initial experience with the Nikkiso centrifugal pump during TAAA repair demonstrated excellent pump function that provided sufficient flow for both distal aortic and selective organ perfusion. The prevention of permanent spinal cord injury and distal organ failure was successful in this group. (J Vasc Surg 1998;27:378-83.)     

Clinical Evaluation of a New Type of Centrifugal Pump

Abstract: The major problems with existing centrifugal pumps are leakage, mechanical trauma, and thrombus formation. In consideration of these problems, a new compact centrifugal pump system was developed. The purpose of this study was to evaluate the new centrifugal pump system clinically. Ten patients underwent open heart surgery with a centrifugal pump or a roller pump. During surgery, hemodynamic and hematological data were obtained. A pulsatile assist device in the pump circuit was used in patients with severe heart disease. There was neither operative death nor hospital mortality, and there was no difference with regard to hemodynamic data between the two groups. The centrifugal pump group, however, had significantly lower hemolysis, especially during prolonged cardiopulmonary bypass. This centrifugal pump could also create sufficient pulsatile flow with a pulsatile assist device. Postoperative macroscopic and microscopic findings demonstrated the smooth surface of the pump without thrombus formation. This centrifugal pump system might be useful for prolonged cardiopulmonary bypass.     

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.     

Significant safety advantages gained with an improved pressure-regulated blood pump

A prototype of a non-occlusive pressure-regulated blood pump (M-pump) was evaluated in-vitro for safety in a comparative study with the roller and centrifugal pumps. The M-pump consists of collapsible tubing of unique design wrapped under tension around a rotor without a stator. The prototype M-pumps were tested in vitro to evaluate performance with respect to flow/ pressure characteristics, hemolysis, bubble generation (cavitation) and durability. The M-pump and centrifugal pump did not overpressurize at any RPM when the pump outlet was occluded, but the roller pump reached pressures in excess of 1000 mmHg. The M-pump did not generate negative pressures upon occlusion of the inlet, whereas the roller and centrifugal pumps produced near-vacuum pressures. Furthermore, the M-pump was unable to empty a blood reservoir when the height of the pump inlet was placed slightly above the reservoir outlet. The levels of microbubbles in the M-pump were significantly lower than the roller and centrifugal pumps upon sudden restriction of the pump inlet as determined with an ultrasonic bubble detector. The results of our in-vitro evaluation of the M-pump have shown it to have lower hemolysis than the centrifugal pump and lower or comparable hemolysis to roller pumps at flowrates of 0.1, 0.5, 4.0 and 6 L/min. We determined that the M-pump design possesses important safety advantages over roller and centrifugal pumps for cardiopulmonary bypass applications.     

Acute experimental study of Abiomed BVS5000 as a V-A bypass to cardiogenic shock models.

PURPOSE: Abiomed BVS5000 is generally used as a ventricular assist device, and there have been no reports of its application to a veno-arterial bypass (V-A bypass). In the present study, we developed a new V-A bypass system using this pump and examined its usefulness experimentally. MATERIALS AND METHODS: Pigs (n=21; 37.4+/-2.2 kg) with cardiogenic shock were divided into the following three groups: (1) Abiomed group (Abiomed BVS5000); (2) nonpulsatile pump (NP)+intra-aortic balloon pump (IABP) group (centrifugal pump and IABP); and (3) NP group. In all three groups, assisted circulation using the pumps was performed for 3 h after the shock. Hemodynamic data and blood specimens were measured before and immediately after the shock, and again at 1, 2, and 3 h after. The individual variations were reduced by evaluation of the measured value/preshock value ratio, not by evaluation of the absolute values. RESULTS: The coronary arterial blood flows at 3 h after the shock were significantly larger in the Abiomed and NP+IABP groups than in the NP group (1.32+/-0.34 and 1.24+/-0.05 vs. 1.05+/-0.11, P<0.05), and the renal arterial and renal cortical tissue blood flows were significantly larger in the Abiomed group than in the NP+IABP and NP groups (renal artery: 1.30+/-0.17 vs. 0.89+/-0.20 and 0.68+/-0.10, P<0.05; renal cortical tissue: 0.74+/-0.25 vs. 0.62+/-0.05 and 0.43+/-0.18, P<0.05). The lactate/pyruvate ratios were significantly lower in the Abiomed groups than in the NP group (25.2+/-1.6 vs. 36.0+/-3.1, P<0.05). CONCLUSION: The results suggest that a V-A bypass using an Abiomed BVS5000 is a useful treatment for organ blood flow redistribution after shock.     

Assisted venous drainage presents the risk of undetected air microembolism

OBJECTIVES: The proliferation of minimally invasive cardiac surgery has increased dependence on augmented venous return techniques for cardiopulmonary bypass. Such augmented techniques have the potential to introduce venous air emboli, which can pass to the patient. We examined the potential for the transmission of air emboli with different augmented venous return techniques. METHODS: In vitro bypass systems with augmented venous drainage were created with either kinetically augmented or vacuum-augmented venous return. Roller or centrifugal pumps were used for arterial perfusion in combination with a hollow fiber oxygenator and a 40-micrometer arterial filter. Air was introduced into the venous line via an open 25-gauge needle. Test conditions involved varying the amount of negative venous pressure, the augmented venous return technique, and the arterial pump type. Measurements were recorded at the following sites: pre-arterial pump, post-arterial pump, post-oxygenator, and patient side. RESULTS: Kinetically augmented venous return quickly filled the centrifugal venous pump with macrobubbles requiring continuous manual clearing; a steady state to test for air embolism could not be achieved. Vacuum-augmented venous return handled the air leakage satisfactorily and microbubbles per minute were measured. Higher vacuum pressures resulted in delivery of significantly more microbubbles to the "patient" (P <.001). The use of an arterial centrifugal pump was associated with fewer microbubbles (P =.02). CONCLUSIONS: Some augmented venous return configurations permit a significant quantity of microbubbles to reach the patient despite filtration. A centrifugal pump has air-handling disadvantages when used for kinetic venous drainage, but when used as an arterial pump in combination with vacuum-assisted venous drainage it aids in clearing air emboli.     

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.     

In Vitro Investigation of the St. Jude Medical Isoflow Centrifugal Pump: Flow Visualization and Hemolysis Studies

Abstract: Centrifugal blood pumps have become valuable therapeutic tools for cardiopulmonary bypass surgery. In addition, surgeons have used them as temporary ventricular assist devices, and this type of pump is also being developed for use as a permanent assist device and total artificial heart. However, centrifugal pumps create flow patterns that are significantly different from those the blood experiences physiologically. The St. Jude Medical Isoflow centrifugal pump has been used clinically during cardiopulmonary bypass surgery, yet no experimental results have been reported that describe the flow patterns within this pump or that quantify the hemolysis generated over a range of operating conditions. The purpose of this study was to investigate the flow patterns and hemolysis during 4 operating conditions. The experimental operating conditions included the design condition (6 L/min, 2,500 rpm, 350 mm Hg), a high flow condition (10 L/min, 2,500 rpm, 330 mm Hg), a low flow condition (2 L/min, 2,500 rpm, 370 mm Hg), and a near surge condition (2 L/min, 3,000 rpm, 550 mm Hg). The flow visualization results demonstrated that the flow within the impeller was well aligned with the impeller blades except near the inlet at the high flow condition. In contrast, the flow through the outlet was well aligned at the high flow condition while there was evidence of particle impact at the design condition, and the flow was disturbed at the low flow and near surge conditions. The indices of hemolysis (IH) for the 3 operating conditions at 2,500 rpm were 0.0082 ± 0.0026 (mean ± SD) for the design condition, 0.0035 ± 0.0014 for the high flow condition, and 0.0326 ± 0.0050 for the low flow condition. The indices for high and low flow were significantly different from that for the design condition (p < 0.05). The IH for the near surge condition (0.0748 ± 0.0039) was significantly higher than that for all other conditions (p < 0.05). In addition to de scribing the flow patterns within the Isoflow, this study independently validated St. Jude Medical's reported IH at the design condition and showed how that IH significantly changed based on operating conditions.     

A Compact Centrifugal Pump for Cardiopulmonary Bypass

A majority of the cardiopulmonary bypass (CPB) systems still utilize bulky roller pumps. A direct-drive small centrifugal pump intended for second-generation CPB pump has been developed. The pump has a 50 mm diameter impeller and provides a 6 L/min flow at 3,000 rpm against 300 mm Hg. A flexible drive shaft allows us to separate the pump head from the console resulting in easier manipulation. An in vitro study showed that the pump generated less hemolysis (index of hemolysis = 0.0011, comparable to the value for Bio-medicus BP-80). To improve blood flow around the shaft-seal region and to reduce thrombus formation around the shaft, six holes were drilled through the impeller. In biventricular bypass experiments using calves, our pump demonstrated excellent antithrombogenicity and durability for 48 h. And the compact and atraumatic centrifugal pump system showed excellent performance and easy manipulation under actual CPB conditions in animal.     

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.     

A Straight Path Centrifugal Blood Pump Concept in the Capiox Centrifugal Pump

Abstract: This article describes comparative studies of a newly developed "straight path" centrifugal pump (Capiox centrifugal pump) targeted for open-heart surgery and circulatory support. A unique straight path design of the rotor was very effective in reducing the pump's rotational speed and prime volume. This pump was evaluated for hydraulics, hemolysis, depriming characteristics, cavitation, and heat generation. Two commercially available centrifugal pumps, the Biomedicus cone-type pump and the Sarns 3M impeller-type pump, were used as controls. The new pump required the lowest pump speed to produce the same flow rates under the same pressure loads and demonstrated the lowest hemolysis and the lowest temperature rise with the outlet clamped. The air volume required to deprime the new pump was one-third to one-half that for the other pumps, and no sign of cavitation was observed even if a small amount of air was introduced to the pump inlet under a negative pressure of 200 mm Hg.     

Evaluation of HL-20 roller pump and Rotaflow centrifugal pump on perfusion quality and gaseous microemboli delivery

The purpose of this study was to compare the HL‐20 roller pump (Jostra USA, Austin, TX, USA) and Rotaflow centrifugal pump (Jostra USA) on hemodynamic energy production and gaseous microemboli (GME) delivery in a simulated neonatal cardiopulmonary bypass (CPB) circuit under nonpulsatile perfusion. This study employed a simulated model of the pediatric CPB including a Jostra HL‐20 heart‐lung machine (or a Rotaflow centrifugal pump), a Capiox BabyRX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Capiox pediatric arterial filter (Terumo Corporation), and ¼‐inch tubing. The total volume of the experimental system was 700 mL (500 mL for the circuit and 200 mL for the pseudo neonatal patient). The hematocrit was maintained at 30% using human blood. At the beginning of each trial, a 5 mL bolus of air was injected into the venous line. Both GME data and pressure values were recorded at postpump and postoxygenator sites. All the experiments were conducted under nonpulsatile perfusion at three flow rates (500, 750, and 1000 mL/min) and three blood temperatures (35, 30, and 25°C). As n = 6 for each setup, a total of 108 trials were done. The total number of GME increased as temperature decreased from 35°C to 25°C in the trials using the HL‐20 roller pump while the opposite effect occurred when using the Rotaflow centrifugal pump. At a given temperature, total GME counts increased with increasing flow rates for both pumps. Results indicated the Rotaflow centrifugal pump delivered significantly fewer microemboli compared to the HL‐20 roller pump, especially under high flow rates. Less than 10% of total microemboli were larger than 40 µm in size and the majority of GME were in the 0–20 µm class in all trials. Postpump total hemodynamic energy (THE) increased with increasing flow rates and decreasing temperatures in both circuits using these two pumps. The HL‐20 roller pump delivered more THE than the Rotaflow centrifugal pump at all tested flow rates and temperature conditions. Results suggest the HL‐20 roller pump delivers more GME than the Rotaflow centrifugal pump but produces more hemodynamic energy under nonpulsatile perfusion mode.     

Characteristics of a Nonocclusive Pressure‐Regulated Blood Roller Pump

For decades, extracorporeal life support (ECLS) systems have relied on pumps designed for short‐term cardiopulmonary bypass. In the past, occlusive roller pumps were the standard. They are being progressively replaced by centrifugal pumps and devices developed specifically for ECLS. However, the ideal pump for long‐term bypass is yet to be created. One interesting alternative is the Rhône‐Poulenc 06 pump that is a nonocclusive pressure‐regulated blood pump developed in France in the 1970s. This pump is composed of a double‐stage rotor with three rollers at each level. The raceway tubing is stretched on the roller and pump occlusivity depends on the tension of the chamber on the rotor. The pump is able to deliver physiological blood flow values without generating dangerous negative or positive pressures. The specific design of the chamber allows the pump to generate a pulsatile flow, inducing minimal blood trauma, and to act as a bubble trap, making it inherently safe. This pump has been used for cardiopulmonary bypass, extracorporeal lung support, and more specifically single‐lumen single‐cannula venovenous membrane oxygenation for neonates, left‐heart or right‐heart assist, and venovenous bypass during liver transplant. In conclusion, this old‐fashion pump is perfectly adapted for any kind of short‐ or long‐term bypass.