Pump-induced haemolysis: a comparison of short-term ventricular assist devices

A comprehensive comparison of the in vitro hemocompatibility of extracorporeal centrifugal blood pumps

Purpose: Blood damage has been associated with patients under temporary continuous-flow mechanical circulatory support. To evaluate the side effects caused by transit blood pumping, in vitro hemocompatibility testing for blood damage in pumps is considered a necessary reference before clinical trials. Methods: The hemocompatibility of five extracorporeal centrifugal blood pumps was investigated comprehensively, including four commercial pumps (the Abbott CentriMag, the Terumo Capiox, the Medos DP3, and the Medtronic BPX-80) and a pump in development (the magAssist MoyoAssist^®). In vitro, hemolysis was tested with heparinized porcine blood at nominal operating conditions (5 L/min, 160 mmHg) and extreme operating conditions (1 L/min, 290 mmHg) using a circulation flow loop. Hematology analyses concerning the blood cell counts and the degradation of high-molecular-weight von Willebrand factor (VWF) during 6-h circulation were also evaluated. Results: Comparing the in vitro hemocompatibility of blood pumps at different operations, the blood damage was significantly more severe at extreme operating conditions than that at nominal operating conditions. The performance of the five blood pumps was arranged in different orders at these two operating conditions. The results also demonstrated superior hemocompatibility of CentriMag and MoyoAssist^® at two operating conditions, with overall low blood damage at hemolysis level, blood cell counts, and degradation of high-molecular-weight VWF. It suggested that magnetic bearings have an advantage in hemocompatibility compared to the mechanical bearing of blood pumps. Conclusion: Involving multiple operating conditions of blood pumps in in vitro hemocompatibility evaluation will be helpful for clinical application. In addition, the magnetically levitated centrifugal blood pump MoyoAssist^® shows great potential in the future as it demonstrated good in vitro hemocompatibility.

The Roles of Membrane Technology in Artificial Organs: Current Challenges and Perspectives

The recent outbreak of the COVID-19 pandemic in 2020 reasserted the necessity of artificial lung membrane technology to treat patients with acute lung failure. In addition, the aging world population inevitably leads to higher demand for better artificial organ (AO) devices. Membrane technology is the central component in many of the AO devices including lung, kidney, liver and pancreas. Although AO technology has improved significantly in the past few decades, the quality of life of organ failure patients is still poor and the technology must be improved further. Most of the current AO literature focuses on the treatment and the clinical use of AO, while the research on the membrane development aspect of AO is relatively scarce. One of the speculated reasons is the wide interdisciplinary spectrum of AO technology, ranging from biotechnology to polymer chemistry and process engineering. In this review, in order to facilitate the membrane aspects of the AO research, the roles of membrane technology in the AO devices, along with the current challenges, are summarized. This review shows that there is a clear need for better membranes in terms of biocompatibility, permselectivity, module design, and process configuration.

Performance characteristics of the new Eurosets magnetically suspended centrifugal pump

OBJECTIVE

The aim was to evaluate the performance of a newly developed magnetically suspended centrifugal pump head intended for use as a ventricular assistance device with a newly developed extracorporeal membrane oxygenator setup.

METHODS

In an experimental setup, an extracorporeal membrane oxygenator circuit was established in three calves with a mean weight of 68.2 ± 2.0 kg. A magnetically levitated centrifugal pump was tested, along with a newly designed extracorporeal membrane oxygenator console, at three different flow ranges: (a) 0.0 to 5.2 L/min, (b) 0.0 to 7.1 L/min, and (c) 0.0 to 6.0 L/min. For each setup, the animals were supported by a circuit for 6 h. Blood samples were collected just before caridiopulmonary bypass (CPB) after 10 min on bypass and after 1, 2, 5, and 6 h of perfusion for hemolysis determination and biochemical tests. Values were recorded for blood pressure, mean flow, and pump rotational speed. Analysis of variance was used for repeated measurements.

RESULTS

Mean pump flows achieved during the three 6 h pump runs for the three pump heads studied were as follows: (a) flow range 0.0 to 5.2 L/min, 3.6 ± 1.5 L/min, (b) flow range 0.0 to 7.1 L/min, 4.9 ± 1.3 L/min, and (c) flow range 0.0 to 6.0 L/min, 3.8 ± 1.5 L/min. Blood trauma, evaluated by plasma hemoglobin and lactate dehydrogenase levels, did not help in detecting any significant hemolysis. Thrombocytes and white blood cell count profiles showed no significant differences between the groups at the end of the 6 h perfusion. At the end of testing, no clot deposition was found in the oxygenator, and there was no evidence of peripheral emboli.

CONCLUSION

The results suggest that the newly developed magnetically suspended centrifugal pump head provides satisfactory hydrodynamic performance in an acute perfusion scenario without increasing hemolysis.

Haemolysis induced by mechanical circulatory support devices: unsolved problems

Since the use of continuous flow blood pumps as ventricular assist devices is standard, the problems with haemolysis have increased. It is mainly induced by shear stress affecting the erythrocyte membrane. There are many investigations about haemolysis in laminar and turbulent blood flow. The results defined as threshold levels for the damage of erythrocytes depend on the exposure time of the shear stress, but they are very different, depending on the used experimental methods or the calculation strategy. Here, the results are resumed and shown in curves. Different models for the calculation of the strengths of erythrocytes are discussed. There are few results reported about tests of haemolysis in blood pumps, but some theoretical approaches for the design of continuous flow blood pumps according to low haemolysis have been investigated within the last years.

Analysis of Haematological and Biochemical Blood Parameters After Electrical Cardioversion of Atrial Fibrillation in Dogs

Introduction

Electrical cardioversion is a therapeutic procedure used to convert various types of arrhythmias back to sinus rhythm. It is used to restore the sinus rhythm in dogs with atrial fibrillation. The effect of the electrical energy used during cardioversion on red blood cells (RBC) is not fully understood. Studies on humans reported lysis of RBC following electrical cardioversion. Similar studies have not been carried out on dogs. The aim of the study was to assess the effect of electrical cardioversion on chosen RBC parameters.

Material and Methods

The study was carried out on 14 large and giant breed dogs weighing from 30 to 84 kg with lone atrial fibrillation (lone AF). Electrical cardioversion was carried out under general anaesthesia by biphasic shock with 70-360 J of energy. Blood was collected at T0 - during atrial fibrillation, prior to cardioversion, and at T1 - 30 min after electrical cardioversion. Complete blood counts as well as total and direct bilirubin concentrations were evaluated. A maximum output of 360 J was used.

Results

In all cases, electrical cardioversion was effective, and no significant changes in the number of RBC and RBC indices were noted. Similarly, there were no statistically significant differences in the levels of total and direct bilirubin.

Conclusion

Electrical cardioversion in dogs led neither to statistically nor clinically significant RBC lysis.

Analysis of haematological and biochemical blood parameters after electrical cardioversion of atrial fibrillation in dogs

Introduction

Electrical cardioversion is a therapeutic procedure used to convert various types of arrhythmias back to sinus rhythm. It is used to restore the sinus rhythm in dogs with atrial fibrillation. The effect of the electrical energy used during cardioversion on red blood cells (RBC) is not fully understood. Studies on humans reported lysis of RBC following electrical cardioversion. Similar studies have not been carried out on dogs. The aim of the study was to assess the effect of electrical cardioversion on chosen RBC parameters.

Material and Methods

The study was carried out on 14 large and giant breed dogs weighing from 30 to 84 kg with lone atrial fibrillation (lone AF). Electrical cardioversion was carried out under general anaesthesia by biphasic shock with 70–360 J of energy. Blood was collected at T0 – during atrial fibrillation, prior to cardioversion, and at T1 – 30 min after electrical cardioversion. Complete blood counts as well as total and direct bilirubin concentrations were evaluated. A maximum output of 360 J was used.

Results

In all cases, electrical cardioversion was effective, and no significant changes in the number of RBC and RBC indices were noted. Similarly, there were no statistically significant differences in the levels of total and direct bilirubin.

Conclusion

Electrical cardioversion in dogs led neither to statistically nor clinically significant RBC lysis.

Evaluation of oxygenators and centrifugal pumps for long-term pediatric extracorporeal membrane oxygenation

Objective: Two extracorporeal membrane oxygenation (ECMO) circuits for children under 10 kg were evaluated and compared for plasma leakage, hemolysis, blood transfusions, and durability. Methods: Group A ( n = 20) was supported by ECMO circuits with the Minimax oxygenator and the Biomedicus centrifugal pump. Group B ( n = 10) was supported by ECMO circuits with the Lilliput 2 ECMO oxygenator and the Rotaflow centrifugal pump. Results: ECMO circuit durability, as measured by oxygenator lifespan, was significantly better in Group B than in Group A (p = 0.04). There was significantly lower hemolysis, measured by plasma free hemoglobin, in Group B ( p = 0.019), and patients in Group B had significantly less need for antithrombin III transfusion ( p = 0.004). No plasma leakage was observed in Group B oxygenators, but plasma leakage was observed in all Group A oxygenators. Conclusion: The combination of a Rotaflow centrifugal pump and Lilliput 2 ECMO oxygenator in pediatric ECMO circuits improved durability and reduced circuit-induced hemolysis. This improvement may be due to the low priming volume, the oxygenator's plasma leakage resistance, the suspended rotor of the centrifugal pump, or a combination of these factors. Perfusion (2007) 22, 323—326.

Plasma Free Hemoglobin Is an Independent Predictor of Mortality among Patients on Extracorporeal Membrane Oxygenation Support

Background

Hemolysis is common in all extracorporeal circuits as evident by the elevated plasma free hemoglobin (PFHb) level. We investigated whether increased hemolysis during extracorporeal membrane oxygenation (ECMO) is an independent mortality predictor.

Methods

We performed a retrospective observational study of consecutive subjects who received ECMO at a tertiary care facility from 2007-2013 to investigate independent predictors of in-hospital mortality. We examined variables related to patient demographics, comorbidities, markers of hemolysis, ECMO characteristics, transfusion requirements, and complications. 24-hour PFHb> 50 mg/dL was used as a marker of severe hemolysis.

Results

154 patients received ECMO for cardiac (n= 115) or pulmonary (n=39) indications. Patients’ mean age was 51 years and 75.3% were males. Compared to nonsurvivors, survivors had lower pre-ECMO lactic acid (p=0.026), lower 24-hour lactic acid (p=0.023), shorter ECMO duration (P=0.01), fewer RBC transfusions on ECMO (p=0.008) and lower level of PFHb 24-hours post ECMO implantation (p=0.029). 24-hour PFHb> 50 mg/dL occurred in 3.9 % versus 15.5% of survivors and nonsurvivors, respectively, p=0.002. A Cox proportional hazard analysis identified PFHb> 50 mg/dL 24-hours post ECMO as an independent predictor of mortality (OR= 3.4, 95% confidence interval: 1.3 – 8.8, p= 0.011).

Conclusion

PFHb> 50 mg/dL checked 24-hour post ECMO implantation is a useful tool to predict mortality. We propose the routine checking of PFHb 24-hours after ECMO initiation for early identification and treatment of the cause of hemolysis.

Pumps in wearable ultrafiltration devices: pumps in wuf devices

The wearable artificial kidney (WAK) is a device that is supposed to operate like a real kidney, which permits prolonged, frequent, and continuous dialysis treatments for patients with end-stage renal disease (ESRD). Its functioning is mainly related to its pumping system, as well as to its dialysate-generating and alarm/shutoff ones. A pump is defined as a device that moves fluids by mechanical action. In such a context, blood pumps pull blood from the access side of the dialysis catheter and return the blood at the same rate of flow. The main aim of this paper is to review the current literature on blood pumps, describing the way they have been functioning thus far and how they are being engineered, giving details about the most important parameters that define their quality, thus allowing the production of a radar comparative graph, and listing ideal pumps' features.

Venoarterial extracorporeal membrane oxygenation for cardiogenic shock and cardiac arrest: a meta-analysis

OBJECTIVE

To evaluate the effect of extracorporeal membrane oxygenation (ECMO) on survival and complication rates in adults with refractory cardiogenic shock or cardiac arrest.

DESIGN

Meta-analysis.

SETTING

University hospitals.

PARTICIPANTS

One thousand one hundred ninety-nine patients from 22 observational studies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Observational studies published from the year 2000 onwards, examining at least 10 adult patients who received ECMO for refractory cardiogenic shock or cardiac arrest were included. Pooled estimates with 95% confidence intervals were calculated based on the Freeman-Tukey double-arcsine transformation and DerSimonian-Laird random-effect model. Survival to discharge was 40.2% (95% confidence intervals [CI], 33.9-46.7), while survival at 3, 6, and 12 months was 55.9% (95% CI, 41.5-69.8), 47.6% (95% CI, 25.4-70.2), and 54.4% (95% CI, 36.6-71.7), respectively. Survival up to 30 days was higher in cardiogenic shock patients (52.5%, 95% CI, 43.7%-61.2%) compared to cardiac arrest (36.2%, 95% CI, 23.1%-50.4%). Concurrently, complication rates were particularly substantial for neurologic deficits (13.3%, 95% CI, 8.3-19.3), infection (25.1%, 95%CI, 15.9-35.5), and renal impairment (47.4%, 95% CI, 30.2-64.9). Significant heterogeneity was detected, although its levels were similar to previous meta-analyses that only examined short-term survival to discharge.

CONCLUSIONS

Venoarterial ECMO can improve short-term survival in adults with refractory cardiogenic shock or cardiac arrest. It also may provide favorable long-term survival at up to 3 years postdischarge. However, ECMO also is associated with significant complication rates, which must be incorporated into the risk-benefit analysis when considering treatment. These findings require confirmation by large, adequately controlled and standardized trials with long-term follow-up.

A multicenter analysis of clinical hemolysis in patients supported with durable, long-term left ventricular assist device therapy

BACKGROUND

Despite the beneficial effects of mechanical circulatory support (MCS), the majority of patients ultimately will have an adverse event. Although hemolysis is common among temporary devices, the incidence and clinical significance of hemolysis in patients managed with long-term, durable left ventricular assist device (LVAD) therapy is largely unknown.

METHODS

Data were obtained from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). All adults who received a continuous-flow LVAD (CF-LVAD) between June 2006 and March 2012 were included. A hemolytic event was defined as a plasma-free hemoglobin >40 mg/dl in association with clinical signs of hemolysis occurring at least 72 hours after LVAD implant. Descriptive statistics, time-dependent analyses and multivariable modeling were employed for statistical purposes.

RESULTS

A total of 4,850 patients followed for a mean of 11.1 months comprised the final study population. There were 340 hemolytic events in 260 patients. Freedom from hemolysis was 97% at 3 months, 94% at 1 year and 91% at 2 years. Mean time from implant to first hemolysis event was 7.4 months. Younger age (<60 years) was independently associated with greater hemolysis (p < 0.001). Thrombotic device malfunction, device exchange and mortality were all significantly higher after hemolysis, with the greatest risk for each occurring within 6 months.

CONCLUSIONS

Hemolysis is not a rare event after CF-LVAD implantation and is associated with an early increase in morbidity and death. Future study should focus on other device and implant characteristics that may lead to hemolytic events, as well as appropriate strategies for managing affected patients.

Mechanical circulatory support

The role for temporary and durable mechanical circulatory support is rapidly expanding. As the use of these technologies continues to grow, the emergency physician has an increasing opportunity to participate in the advancement of these potentially life-saving technologies. This review discusses the current role of the intra-aortic balloon pump in cardiogenic shock, describes the complications and management strategies for the critically ill patient with a left ventricular assist device, and explores the emerging role of ECMO in the emergency department for patients presenting in refractory cardiogenic shock and cardiac arrest.

A comparison study of haemolysis production in three contemporary centrifugal pumps

One challenge in providing extracorporeal circulation is to supply optimal flow while minimising adverse effects, such as haemolysis. To determine if the recent generation constrained vortex pumps with their inherent design improvements would lead to reduced red cell trauma, we undertook a study comparing three devices. Utilizing a simulated short-term ventricular assist circuit primed with whole human blood, we examined changes in plasma free haemoglobin values over a six-day period. The three pumps investigated were the Maquet Rotaflow, the Levitronix PediVAS and the Medos Deltastream DP3.This study demonstrated that all three pumps produced low levels of haemolysis and are suitable for use in a clinical environment. The Levitronix PediVAS was significantly less haemolytic than either the Rotaflow (p<0.05) or the DP3 (p<0.05). There was no significant difference in plasma free haemoglobin between the Rotaflow and the DP3 (p=0.71).

Comparison of hemolysis between CentriMag and RotaFlow rotary blood pumps during extracorporeal membrane oxygenation

The purpose of this investigation was to compare the hemolysis levels for patients on extracorporeal membrane oxygenation (ECMO) incorporating two different rotary blood pumps (CentriMag [CMAG] and RotaFlow [RF]) in identical circuits otherwise. The difference between the two pumps is the cost. One is 20-30 times less expensive than the other. A retrospective analysis of all patients placed on ECMO from June 2008 through May 2012 was done to evaluate hemolysis. Daily plasma hemoglobin (pHb), lactate dehydrogenase (LDH), and lactate levels were collected on all patients. Values were compared between those patients who received a CMAG and those who received an RF. Patients had to be on ECMO for more than 2 days to be included in the study. Linear mixed effects models were fit to the data to assess differences over time for each continuous outcome. Forty patients were placed on ECMO incorporating CMAG, whereas 40 patients received an RF. There were no significant statistical differences between CMAG and RF groups when comparing days on support (8.7 ± 5.0; 8.4 ± 5.7), age (44.8 ± 18.3; 46.1 ± 16.0), body surface area (2.03 ± 0.36; 1.96 ± 0.31), gender (male: 58%, female: 42%; male: 55%, female: 45%), etiology, type of support (veno-arterial [VA)]: 78%, veno-venous [VV)]: 22%; VA: 82%, VV: 18%) and pre-ECMO LDH levels (4004.0 ± 3583.2; 3603.7 ± 3354.1). There were also no significant differences between the CMAG and RF groups when comparing the mean values for daily pHb levels (5.7 ± 3.6; 5.7 ± 4.2), lactate levels (2.8 ± 1.9; 3.0 ± 2.1), and LDH levels (2656.3 ± 1606.8; 2688.6 ± 1726.1) or daily lactate, LDH, and pHb levels for the first 10 days of support. From our investigation, there is no difference between the CMAG and the RF blood pumps in regard to the creation of hemolysis during ECMO. The difference in cost of the devices does not correlate with the performance and outcomes.

New generation extracorporeal membrane oxygenation with MedTech Mag-Lev, a single-use, magnetically levitated, centrifugal blood pump: preclinical evaluation in calves

We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, MedTech Mag-Lev, in a 3-week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio-Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH-R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio-Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200-240 s. All the MedTech ECMO calves completed the study duration. However, the Bio-Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the MedTech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO2 of the oxygenator outlet was higher than 400 mm Hg with the PCO2 below 45 mm Hg. Hemolysis and thrombus were not seen in the MedTech ECMO circuits (plasma-free hemoglobin [PFH] < 5 mg/dL), while severe hemolysis (PFH > 20 mg/dL) and large thrombus were observed in the Bio-Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three-week cardiopulmonary support was performed successfully with the MedTech ECMO without circuit exchanges. The MedTech Mag-Lev could help extend the durability of ECMO circuits by the improved biocompatible performances.

Have changes in ECMO technology impacted outcomes in adult patients developing postcardiotomy cardiogenic shock?

Extracorporeal membrane oxygenation (ECMO) technology has undergone several advancements over the last decade. We sought to compare current ECMO technology to older ones to determine how these technological improvements have impacted outcomes in patients suffering from postcardiotomy cardiogenic shock (PCS). Between 2005 and 2010, 49 patients received ECMO as support for PCS following elective cardiac surgery. Patients were divided into three groups. Group 1 (Gp 1, n = 11) patients received a Biomedicus pump with an Affinity oxygenator, Group 2 (Gp 2, n = 11) patients received a Biomedicus pump with a Quadrox D oxygenator, and Group 3 (Gp 3, n = 27) patients received a Rotaflow pump with a Quadrox D oxygenator. Groups were compared with regards to adverse events and ability to wean. Adverse event analysis showed no statistically significant difference between groups in incidence of stroke (p = 0.08), renal failure (p = 0.88), or bleeding requiring reexploration (p = 0.10). Changes in technology did little to improve weaning rates from ECMO (Gp 1 = 63.6%, Gp 2 = 45.5%, and Gp 3 = 55.6%). Similar trends were detected in hospital survival (Gp 1 = 27.3%, Gp 2 = 27.3%, and Gp 3 = 33.3%). Technology did impact oxygenator durability with Gp 1 requiring seven (63.6%) oxygenator exchanges compared to zero (0.0%) in Gp 2 and two (7.4%) in Gp 1. While advancements in ECMO technology have resulted in improved oxygenator durability, outcomes in patients requiring such support for PCS continue to be poor.

Retrieval of critically ill adults using extracorporeal membrane oxygenation: an Australian experience

PURPOSE

A retrieval program was developed in New South Wales (NSW), Australia to provide extracorporeal membrane oxygenation support (ECMO) for the safe transport of adults with severe, acute respiratory or cardiac failure. We describe the development and results of this program and the impact of the 2009 H1N1 epidemic on this service.

METHODS

An observational study of all patients who were retrieved on ECMO support in NSW, from March 1, 2007 to June 1, 2010, was carried out.

RESULTS

Forty adult patients were retrieved on ECMO support (median age 34 years). The indications for retrieval were respiratory in 38 patients (of whom 16 were confirmed or suspected H1N1 cases) and cardiac in 2 patients. Two other patients died after referral but before ECMO support could be established. Patients were transported by road (n = 26, 65%), medical retrieval jet (n = 10, 25%) and helicopter (n = 4, 10%). The median retrieval distance was 250 km (range 12-1,960 km). Thirty-four patients (85%) survived to hospital discharge. Survival for respiratory indications was 87% (33/38 patients) and 50% (1/2 patients) for cardiac indications. There were no deaths or major morbidity associated with these retrievals.

CONCLUSIONS

Patients with very severe respiratory failure, which was considered to preclude conventional ventilation for safe transfer to tertiary centres, were managed by an ECMO referral and retrieval program in NSW and had a high rate of survival. This program also enhanced the capacity of the state to respond to a surge in demand for ECMO support due to the H1N1 epidemic, although the role of ECMO in respiratory failure is not yet well defined.

Mechanical support in childhood heart failure

Despite optimization of standard medical therapy, some patients with chronic heart failure will deteriorate to the point that they require hospitalization for intravenous therapies and inpatient monitoring. Once the condition is recognized, the therapeutic goals are to reverse hemodynamic derangements, correct metabolic abnormalities, and provide symptomatic relief. Achievement of these goals requires individualized care and a familiarity with the risks and benefits of particular therapies.

An investigational study of minimum rotational pump speed to avoid retrograde flow in three centrifugal blood pumps in a pediatric extracorporeal life support model

During extracorporeal life support with centrifugal blood pumps, retrograde pump flow may occur when the pump revolutions decrease below a critical value determined by the circuit resistance and the characteristics of the pump. We created a laboratory model to evaluate the occurrence of retrograde flow in each of three centrifugal blood pumps: the Rotaflow, the CentriMag, and the Bio-Medicus BP-50. At simulated patient pressures of 60, 80, and 100 mmHg, each pump was evaluated at speeds from 1000 to 2200 rpm and flow rates were measured. Retrograde flow occurred at low revolution speeds in all three centrifugal pumps. The Bio-Medicus pump was the least likely to demonstrate retrograde flow at low speeds, followed by the Rotaflow pump. The CentriMag pump showed the earliest transition to retrograde flow, as well as the highest degree of retrograde flow. At every pump speed evaluated, the Bio-Medicus pump delivered the highest antegrade flow and the CentriMag pump delivered the least.

Mechanical performance comparison between RotaFlow and CentriMag centrifugal blood pumps in an adult ECLS model

Introduction: Centrifugal blood pumps have been widely adopted in conventional adult cardiopulmonary bypass and circulatory assist procedures. Different brands of centrifugal blood pumps incorporate distinct designs which affect pump performance. In this adult extracorporeal life support (ECLS) model, the performances of two brands of centrifugal blood pump (RotaFlow blood pump and CentriMag blood pump) were compared.

Methods: The simulated adult ECLS circuit used in this study included a centrifugal blood pump, Quadrox D membrane oxygenator and Sorin adult ECLS tubing package. A Sorin Cardiovascular® VVR® 4000i venous reservoir (Sorin S.p.A., Milan, Italy) with a Hoffman clamp served as a pseudo-patient. The circuit was primed with 900ml heparinized human packed red blood cells and 300ml lactated Ringer’s solution (total volume 1200 ml, corrected hematocrit 40%). Trials were conducted at normothermia (36°C). Performance, including circuit pressure and flow rate, was measured for every setting analyzed.

Results: The shut-off pressure of the RotaFlow was higher than the CentriMag at all measurement points given the same rotation speed (p < 0.0001). The shut-off pressure differential between the two centrifugal blood pumps was significant and increased given higher rotation speeds (p < 0.0001). The RotaFlow blood pump has higher maximal flow rate (9.08 ± 0.01L/min) compared with the CentriMag blood pump (8.37 ± 0.02L/min) (p < 0.0001). The blood flow rate differential between the two pumps when measured at the same revolutions per minute (RPM) ranged from 1.64L/min to 1.73L/min.

Conclusions: The results obtained in this experiment demonstrate that the RotaFlow has a higher shut-off pressure (less retrograde flow) and maximal blood flow rate than the CentriMag blood pump. Findings support the conclusion that the RotaFlow disposable pump head has a better mechanical performance than the CentriMag. In addition, the RotaFlow disposable pump is 20-30 times less expensive than the CentriMag.

Extracorporeal cardiopulmonary resuscitation in refractory pediatric cardiac arrest

The purpose of this article is to discuss the indications for extracorporeal cardiopulmonary resuscitation (ECPR), physiologic and mechanical issues that arise in patients managed with ECPR, and optimal patient selection for ECPR. ECPR can provide very good outcomes for some children who, in all likelihood, would otherwise have died. Having the capability to routinely offer ECPR represents an enormous institutional commitment of people and resources. For ECPR to be successful, it must be rapidly deployed, patients must be selected with care, and consistently excellent conventional CPR must take place while awaiting ECPR.

Use of a ventricular assist device as a bridge to transplantation in a patient with single ventricle physiology and total cavopulmonary anastomosis

Mechanical circulatory support can be used to manage acute and chronic cardiac failure in both adult and pediatric patients. Traditionally, extracorporeal membrane oxygenation (ECMO) has been the most common form of mechanical circulatory support in children. However, more recently, in cases of pure ventricular dysfunction, ventricular assist devices (VADs) have offered specific advantages over ECMO, including better ventricular recovery, reduced anticoagulation requirements, decreased use of blood products and decreased cost. We present the use of a VAD in an adolescent with single-ventricle physiology, who could not be weaned from cardiopulmonary bypass (CPB) after undergoing a revision of a modified Fontan operation. Gas exchange was provided by the patient's lungs while the centrifugal VAD was used successfully to support the circulation as a bridge, first to a totally implantable pulsatile VAD and subsequently to heart transplantation.

Postoperative support with the centrifugal pump ventricular assist device (VAD)

Centrifugal pump left ventricular assist device is a useful adjunct in pediatric cardiac surgery, as a bridge to recovery, or in some cases, to transplantation. This form of circulatory support may not have the universal applicability of extracorporeal membrane oxygenation, but it is equally or more effective in properly selected patients. The technology for centrifugal pump support is now quite standardized, and the advantages well documented. In this chapter we discuss the problems of indications, case selection, technical aspects of the circuit, and general clinical management. Results since 1989 are also presented.

Comparison of a Tubular Pulsatile Pump and a Volumetric Pump for Continuous Venovenous Renal Replacement Therapy in a Pediatric Animal Model

We compare the efficacy of a tubular pulsatile pump and a conventional volumetric pump (IVAC 571), connected to a neonatal hemofiltration circuit with an FH22 filter, for continuous renal replacement therapy in 54 Maryland pigs weighing 8-16 kg. Three different flow rates (30 ml/min in 12 cases, 15 ml/min in 22 cases, and 5 ml/min in 20 cases) were used over a 2-hour period. Hemofiltration and hemodiafiltration were performed, and measurements of ultrafiltrate flow, circuit pressures, heart rate, blood pressure, temperature, urea, creatinine, total proteins, Na, K, Cl, hematocrit, and hemolysis parameters (aspartate transaminase, lactic dehydrogenase, haptoglobin, indirect bilirubin, free hemoglobin) were made. There were no differences in ultrafiltrate flow between the two pumps. Ultrafiltrate volume was significantly higher with higher flows (p < 0.01). The technique was well tolerated by all pigs. When each blood flow was analyzed separately, cross-filter pressure drop was significantly higher in the volumetric pump than in the tubular pulsatile pump (p < 0.05). No significant differences in heart rate, blood pressure, or analytical determinations were seen between the two pumps. We conclude that pulsatile and volumetric pumps can be uses as an alternative to roller pumps for continuous venovenous renal replacement therapy in neonates and infants.