Comparison of Coagulation Parameters,Anticoagulation, and Need for Transfusion in Patients on Interventional Lung Assist or Veno‐Venous Extracorporeal Membrane Oxygenation

Clinical data on anticoagulation needs of modern extracorporeal membrane oxygenation (ECMO) and its impact on coagulation are scarce. Therefore, we analyzed coagulation‐related parameters, need for transfusion, and management of anticoagulation in adult patients with severe acute respiratory failure during treatment with either pumpless interventional lung assist (iLA) or veno‐venous ECMO (vv‐ECMO). Sixty‐three patients treated with iLA and 192 patients treated with vv‐ECMO at Regensburg University Hospital between January 2005 and May 2011 were analyzed. Data related to anticoagulation, transfusion, and coagulation parameters were collected prospectively by the Regensburg ECMO registry. Except for a higher, sequential organ failure assessment (SOFA) score in the ECMO group (12 [9–15] vs. 11 [7–14], P = 0.007), a better oxygenation, and a lower dosage of vasopressors in the iLA patients, both groups had similar baseline characteristics. No difference was noted in terms of outcome and overall transfusion requirements. Factors of the plasmatic coagulation system were only marginally altered over time and did not differ between groups. Platelet counts in ECMO‐treated patients, but not in those treated with iLA, dropped significantly during extracorporeal support. A more intense systemic anticoagulation with a mean activated partial thromboplastin time (aPTT) > 53 s led to a higher need for transfusions compared with the group with a mean aPTT < 53 s, whereas the average durability of membrane oxygenators was not affected. Need for red blood cell (RBC) transfusion was highest in patients with extrapulmonary sepsis (257 mL/day), and was significantly lower in primary pulmonary adult respiratory distress syndrome (ARDS) (102 mL/day). Overall, 110 (0–274) mL RBC was transfused in the ECMO group versus 146 (41–227) mL in the iLA group per day on support. The impact of modern iLA and ECMO systems on coagulation allows comparatively safe long‐term treatment of adult patients with acute respiratory failure. A moderate systemic anticoagulation seems to be sufficient. Importantly, platelets are more affected by vv‐ECMO compared with pumpless iLA.     

Silicon Micropore‐Based Parallel Plate Membrane Oxygenator

Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas‐permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water‐based bench‐top set‐up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM‐PDMS membranes was 3.03 ± 0.42 mL O₂ min^?1 m^?2 cm Hg^?1 with pure water and 1.71 ± 1.03 mL O₂ min^?1 m^?2 cm Hg^?1 with blood. An analytic model to predict gas transport was developed using data from the bench‐top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM‐PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators.     

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.     

Evolution of Technology,Establishment of Program,and Clinical Outcomes in Pediatric Extracorporeal Membrane Oxygenation: The “SickKids” Experience

Technological development has had a tremendous impact on the management of patients who require extracorporeal membrane oxygenation (ECMO). Team development and education are a vital component of a successful extracorporeal life support (ECLS) Program to reduce complications and subsequently improve clinical outcomes. We sought to review the evolution in technology, importance of team development and training, and report our experience at The Hospital for Sick Children, Toronto. There were a total of 576 ECMO runs in 534 patients (42 repeat ECMO runs) between January 1988 and June 2012. The use of ECMO for cardiac disease has increased in the last decade due to an expanded indication for ECMO in patients with single‐ventricle physiology. Cardiac ECMO still remains a challenge in terms of survival (177/392, 45%). Although development of an ECLS program and team education facilitated extracorporeal cardiopulmonary resuscitation, clinical outcomes were not satisfactory (survival, 33%). The most common complications were hemorrhagic (13.8%), followed by renal (10.6%) and pulmonary dysfunction (6.9%). Advances in technology made management during ECMO safer, and the mechanical complications related to the ECMO system were 6.1%, including circuit changes due to thrombus formation, cannula repositioning, or optimization of size.     

The Impact of Renal Failure and Renal Replacement Therapy on Outcome During Extracorporeal Membrane Oxygenation Therapy

Acute kidney injury (AKI) is common in patients treated with veno‐arterial (VA‐) or veno‐venous (VV‐) extracorporeal membrane oxygenation (ECMO). In this setting, the use of continuous renal replacement therapy (CRRT) can help to optimize fluid status but may also negatively impact on patients' outcome. In contrast, the relationship between AKI, CRRT, and survival in critically ill adult patients receiving ECMO is not well defined. The institutional ECMO database (n = 162) from November 2008 to December 2013, excluding patients with ICU survival <24 hours was reviewed. Demographics, co‐morbidities, and concomitant therapies for all patients were collected. AKI was defined according to the Acute Kidney Injury Network (AKIN) criteria. ICU mortality was noted. Data were retrieved for 135 patients (79 with VA‐ECMO and 56 with VV‐ECMO). Of these, 95 developed AKI, 63 (47%) of whom required CRRT; thus three groups of patients were identified: (a) no AKI; (b) AKI without CRRT (AKI_NOCRRT); and (c) CRRT with AKI (AKI_CRRT). AKI_NOCCRT patients were more likely to have preexisting heart disease, to be more severely ill, and to be treated with VA‐ECMO than those without AKI. AKI_CRRT patients were also more likely to be treated with VA‐ECMO, had more organ dysfunction at the time of ECMO insertion, and needed more transfusions and inotropic agents than patients without AKI. ICU mortality was 53% (72/135) and was similar in the three groups, even when different AKI stages or VA/VV‐ECMO were analyzed separately. In this study, the use of CRRT was not associated with an increased mortality in an adult population of patients treated with ECMO, even after adjustment for confounders.     

Conduta em obstrução por coágulo em cânula de duplo lúmen bicaval após diagnóstico guiado por ETE: relato de caso

BackgroundVeno‐venous extracorporeal membrane oxygenation is an established therapy for patients with refractory acute respiratory distress syndrome (ARDS). One complication related to the use of veno‐venous extracorporeal membrane oxygenation is thrombosis despite proper anticoagulation. We report the diagnosis and management of a clot‐obstruction in a single site cannula placed through the internal jugular vein, guided by transesophageal echocardiography.Case reportA 39 year‐old male developed acute respiratory distress syndrome and hemodynamic instability after an episode of pulmonary aspiration in the ICU. Eight hours after placement of a single site veno‐venous extracorporeal membrane oxygenation, suddenly the perfusionist noticed a reduction in flow. TEE showed a thrombus‐like mass obstructing the inflow port in SVC and inflow at IVC was intact. After unsuccessful attempts to reposition the cannula, the team decided to insert additional femoral inflow cannula through the IVC. The single site catheter was then pulled out until its tip was positioned in the right atrium and all three ports of the catheter were switched to the infusion ports. After this, flows and oxygenation improved significantly. Unfortunately, despite all of the efforts, the patient died 2 days later.DiscussionThe diagnosis of veno‐venous extracorporeal membrane oxygenation cannula obstruction is based on reduced inflow rates, hemodynamic instability and poor oxygenation of blood. TEE allows evaluation of the flows inside the cannula and in this case, an obstruction was found. The management presented points to the fact that in a situation of catheter obstruction caused by a clot, there is a feasible alternative to assure minimal interruption of the hemodynamic support offered by the veno‐venous extracorporeal membrane oxygenation.     

New trends in extracorporeal membrane oxygenation in newborn pulmonary diseases

New trends in extracorporeal membrane oxygenation (ECMO) for respiratory failure in the newborn were reviewed. Following a decade of clinical research, ECMO is now the standard treatment for newborn respiratory failure when all other conventional less-invasive treatment options have been exhausted. As of July 2000, 15,525 newborns with respiratory failure treated with ECMO have been entered into the registry of the Extracorporeal Life Support Organization with an overall survival rate of 78%. The latest improvement in ECMO technology in this group of patients includes minimally invasive modes of vascular access through percutaneous approaches to minimize morbidity. However, with advances in modes of mechanical ventilation, including high-frequency ventilation and the introduction of inhaled nitric oxide, the use and necessity for ECMO have clearly diminished for newborn respiratory failure.     

Extracorporeal Membrane Oxygenation Can Save Lives in Children With Heart or Lung Failure After Liver Transplantation

The risk of cardiac or lung failure after liver transplantation (LT) is significant. In rare cases, the usual intensive care techniques fail to maintain organ oxygenation with a risk of multiorgan dysfunction. Although extracorporeal membrane oxygenation (ECMO) is a difficult and risky procedure, it can be proposed as life‐saving. Four children with either acute pulmonary (three) or cardiac (one) failure after LT, and the criteria that decided the use of ECMO (level of ventilation and results, dosage of inotropic drugs, cardiac ultrasound, blood lactate) were retrospectively reported. These patients, 1–11 years old, were treated with either veno‐arterial (three) or veno‐venous (one) ECMO. Two experienced a full recovery, with 3 and 6 years of follow‐up. Two died of systemic inflammatory response syndrome (SIRS) due to ECMO, and relapse of heart failure due to the underlying disease. Although our patients' survival was only 50%, we showed that ECMO can be useful in children after LT. It should be considered before the development of irreversible multiorgan failure.     

Do We Need Heparin Coating for Extracorporeal Membrane Oxygenation? New Concepts and Controversial Positions About Coating Surfaces of Extracorporeal Circuits

Blood contact with surfaces of the extracorporeal circuit provokes the activation of the coagulation system. To improve biocompatibility of the extracorporeal circuit without increasing the risk of bleeding, coatings of artificial surfaces were designed; many of them involve the use of heparin. Data in the literature show that heparin‐induced thrombocytopenia is a major issue in the extracorporeal membrane oxygenation scenario, and no relevant benefits have been shown comparing heparin and no‐heparin coating.     

Extracorporeal membrane oxygenation in pregnancy and the postpartum period: a systematic review of case reports

The use of extracorporeal membrane oxygenation (ECMO) as salvage therapy for patients with severe cardiopulmonary failure has increased significantly in the past decade. However, the use of ECMO in pregnant and peripartum patients has received scant attention. We performed a systematic review of case reports in the literature, documenting indications and outcomes of ECMO in pregnancy and postpartum patients. Case reports on ECMO use in pregnant and postpartum patients were retrieved from MEDLINE, EMBASE and SCOPUS databases up to December 2018. Ninety publications reporting on 97 patients met our inclusion criteria. The majority of publications reported peripartum or postpartum ECMO use for cardiovascular failure (60.8%), while the remainder had respiratory failure. Adult Respiratory Distress Syndrome (91.9%) was the most common respiratory indication while pulmonary embolism (23.7%) and peripartum cardiomyopathy (16.9%) accounted for the two most common cardiovascular indications. Hemorrhage was the most common complication of ECMO reported (31.9%). Of 96 documented neonatal outcomes, 80 neonates (83.3%) survived while 88 of 97 (90.7%) mothers survived. Extracorporeal membrane oxygenation appears to be a viable life support modality in pregnant and postpartum women with severe cardiopulmonary failure, but publication bias in our study cohort should be considered.     

Induced Cell Trauma During in Vitro Perfusion: A Comparison Between Two Different Perfusion Systems

The purpose of this study was to compare blood cell activation during in vitro long-term perfusion using 2 parallel in vitro extracorporeal membrane oxygenation (ECMO) systems. We compared two substantially different perfusion systems, an assistance respiratoire extra corporelle (AREC) system on one hand, containing an AREC pump, silicon tubing, and a hollow-fiber oxygenator, and a centrifugal pump system, on the other hand, containing a Biomedicus centrifugal pump, PVC tubing, and a membrane oxygenator. We measured the platelet count using an automated blood cell counter. Platelet activation was evaluated using a flow cytometric technique for the platelet membrane expression of glycoproteins and ELISA for the plasma concentration of β-thromboglobulin (β-TG), a platelet specific protein released into the blood upon platelet activation. The neutrophil count was assayed using an automated blood cell counter and the plasma concentration of cytokines using an ELISA kit. A significant difference between the two systems was observed in terms of the platelet membrane expression of glycoprotein (GP)Ib (p = 0. 0001) and GPIIb/IIIa (p = 0.0037), indicating a lower degree of platelet activation in the AREC system. The concentration of neutrophils was significantly lower in the centrifugal system (p = 0.002) compared to the AREC system. The neutrophil membrane expression of CD11b was significantly lower (p = 0.0067) in the AREC system, indicating a lower degree of neutrophil activation compared to the centrifugal pump system. A significantly lower degree of hemolysis, as expressed by plasma hemoglobin, was observed in the AREC pump system (p = 0.0491). In conclusion, lower degrees of the platelet membrane expression of GPIb and GPIIb/IIIa and of the neutrophil membrane expression of CD11b were observed in the AREC system, indicating a lower degree of platelet and neutrophil activation in this system. No significant difference between the two systems as to the plasma concentration of interleukin (IL)-1β, IL-6, or IL-8 could be recorded. Further studies are warranted to specify the role of each individual component of the two systems.     

Comparison of Two Types of Neonatal Extracorporeal Life Support Systems With Pulsatile and Nonpulsatile Flow

We compared the effects of two neonatal extracorporeal life support (ECLS) systems on circuit pressures and surplus hemodynamic energy levels in a simulated ECLS model. The clinical set‐up included the Jostra HL‐20 heart–lung machine, either the Medtronic ECMO (0800) or the MEDOS 800LT systems with company‐provided circuit components, a 10 Fr arterial cannula, and a pseudo‐patient. We tested the system in nonpulsatile and pulsatile flow modes at two flow rates using a 40/60 glycerin/water blood analog, for a total of 48 trials, with n = 6 for each set‐up. The pressure drops over the Medtronic ECLS were significantly higher than those over the MEDOS system regardless of the flow rate or perfusion mode (144.8 ± 0.2 mm Hg vs. 35.7 ± 0.2 mm Hg, respectively, at 500 mL/min in nonpulsatile mode, P < 0.001). The preoxygenator mean arterial pressures were significantly increased and the precannula hemodynamic energy values were decreased with the Medtronic ECLS circuit. These results suggest that the MEDOS ECLS circuit better transmits hemodynamic energy to the patient, keeps mean circuit pressures lower, and has lower pressure drops than the Medtronic Circuit.     

13C Breath Tests Are Feasible in Patients With Extracorporeal Membrane Oxygenation Devices

Temporary extracorporeal membrane oxygenation (ECMO) has been established as an essential part of therapy in patients with pulmonary or cardiac failure. As physiological gaseous exchange is artificially altered in this patient group, it is debatable whether a ¹³C‐breath test can be carried out. In this proof of technical feasibility report, we assess the viability of the ¹³C‐breath test LiMAx (maximum liver function capacity) in patients on ECMO therapy. All breath probes for the test device were obtained directly via the membrane oxygenator. Data of four patients receiving liver function assessment with the ¹³C‐breath test LiMAx while having ECMO therapy were analyzed. All results were compared with validated scenarios of the testing procedures. The LiMAx test could successfully be carried out in every case without changing ECMO settings. Clinical course of the patients ranging from multiorgan failure to no sign of liver insufficiency was in accordance with the results of the LiMAx liver function test. The ¹³C‐breath test is technically feasible in the context of ECMO. Further evaluation of ¹³C‐breath test in general would be worthwhile. The LiMAx test as a ¹³C‐breath test accessing liver function might be of particular predictive interest if patients with ECMO therapy develop multiorgan failure.     

Physiologic Benefits of Pulsatile Perfusion During Mechanical Circulatory Support for the Treatment of Acute and Chronic Heart Failure in Adults

A growing population experiencing heart failure (100 000 patients/year), combined with a shortage of donor organs (less than 2200 hearts/year), has led to increased and expanded use of mechanical circulatory support (MCS) devices. MCS devices have successfully improved clinical outcomes, which are comparable with heart transplantation and result in better 1‐year survival than optimal medical management therapies. The quality of perfusion provided during MCS therapy may play an important role in patient outcomes. Despite demonstrated physiologic benefits of pulsatile perfusion, continued use or development of pulsatile MCS devices has been widely abandoned in favor of continuous flow pumps owing to the large size and adverse risks events in the former class, which pose issues of thrombogenic surfaces, percutaneous lead infection, and durability. Next‐generation MCS device development should ideally implement designs that offer the benefits of rotary pump technology while providing the physiologic benefits of pulsatile end‐organ perfusion.     

Laboratory Evaluation of Hemolysis and Systemic Inflammatory Response in Neonatal Nonpulsatile and Pulsatile Extracorporeal Life Support Systems

The objective of this study was to compare the systemic inflammatory response and hemolytic characteristics of a conventional roller pump (HL20‐NP) and an alternative diagonal pump with nonpulsatile (DP3‐NP) and pulsatile mode (DP3‐P) in simulated neonatal extracorporeal life support (ECLS) systems. The experimental neonatal ECLS circuits consist of a conventional Jostra HL20 roller pump or an alternative Medos DP3 diagonal pump, and Medos Hilite 800 LT hollow‐fiber oxygenator with diffusion membrane. Eighteen sterile circuits were primed with freshly donated whole blood and divided into three groups: conventional HL20 with nonpulsatile flow (HL20‐NP), DP3 with nonpulsatile flow (DP3‐NP), and DP3 with pulsatile flow (DP3‐P). All trials were conducted for durations of 12 h at a flow rate of 500 mL/min at 36°C. Simultaneous blood flow and pressure waveforms were recorded. Blood samples were collected to measure plasma‐free hemoglobin (PFH), human tumor necrosis factor‐alpha, interleukin‐6 (IL‐6), and IL‐8, in addition to the routine blood gas, lactate dehydrogenase, and lactic acid levels. HL20‐NP group had the highest PFH levels (mean ± standard error of the mean) after a 12‐h ECLS run, but the difference among groups did not reach statistical significance (HL20‐NP group: 907.6 ± 253.1 mg/L, DP3‐NP group: 343.7 ± 163.2 mg/L, and DP3‐P group: 407.6 ± 156.6 mg/L, P = 0.06). Although there were similar trends but no statistical differences for the levels of proinflammatory cytokines among the three groups, the HL20‐NP group had much greater levels than the other groups (P > 0.05). Pulsatile flow generated higher total hemodynamic energy and surplus hemodynamic energy levels at pre‐oxygenator and pre‐clamp sites (P < 0.01). Our study demonstrated that the alternative diagonal pump ECLS circuits appeared to have less systemic inflammatory response and hemolysis compared with the conventional roller pump ECLS circuit in simulated neonatal ECLS systems. Pulsatile flow delivered more hemodynamic energy to the pseudo‐patient without increased odds of hemolysis compared with the conventional, nonpulsatile roller pump group.     

ROBOTIC TECHNOLOGY IN SURGERY: CURRENT STATUS IN 2008

There is increasing patient and surgeon interest in robotic‐assisted surgery, particularly with the proliferation of da Vinci surgical systems (Intuitive Surgical, Sunnyvale, CA, USA) throughout the world. There is much debate over the usefulness and cost‐effectiveness of these systems. The currently available robotic surgical technology is described. Published data relating to the da Vinci system are reviewed and the current status of surgical robotics within Australia and New Zealand is assessed. The first da Vinci system in Australia and New Zealand was installed in 2003. Four systems had been installed by 2006 and seven systems are currently in use. Most of these are based in private hospitals. Technical advantages of this system include 3‐D vision, enhanced dexterity and improved ergonomics when compared with standard laparoscopic surgery. Most procedures currently carried out are urological, with cardiac, gynaecological and general surgeons also using this system. The number of patients undergoing robotic‐assisted surgery in Australia and New Zealand has increased fivefold in the past 4 years. The most common procedure carried out is robotic‐assisted laparoscopic radical prostatectomy. Published data suggest that robotic‐assisted surgery is feasible and safe although the installation and recurring costs remain high. There is increasing acceptance of robotic‐assisted surgery, especially for urological procedures. The da Vinci surgical system is becoming more widely available in Australia and New Zealand. Other surgical specialties will probably use this technology. Significant costs are associated with robotic technology and it is not yet widely available to public patients.     

Evaluation of high-frequency jet ventilation in oxygenation through an artificial membrane lung

The membrane oxygenator often develops impaired gas exchange after prolonged use because plasma proteins adhere to the membrane's surface and leak through its micropores. This study was performed to examine the efficacy of high-frequency jet ventilation (HFJV) in minimizing these problems in a "flat plate" type of membrane oxygenator. We first vibrated the membrane of the oxygenator by HFJV from 1 to 10 Hz to find the frequency most effective for optimal gas exchange in animals with partial extracorporeal circulation. These studies suggested that 6 Hz HFJV was preferable in our model. We subsequently performed in vivo extracorporeal oxygenation in dogs for 8 h using the membrane oxygenator with or without 6 Hz HFJV. Although the gas exchange capacity within the first 8 h was similar in the two groups, after 6 h a significant decrease in the red blood cell count and in the hematocrit was found in the group not receiving HFJV. Scanning electron microscopic examination of the membranes after 8 h of use disclosed that the membrane from the group receiving HFJV had less plasma protein and fibrin adhesion than that from the group not receiving HFJV. Moreover, it appears that with prolonged extracorporeal oxygenation, 6 Hz HFJV also protects against a decrease in the hematocrit of the passed blood and might lead to enhanced gas exchange. Our data suggest that good gas exchange can be maintained for periods even longer than 8 h if HFJV is used in conjunction with the membrane oxygenator.     

In Vivo Assessment of a New Method of Pulsatile Perfusion Based on a Centrifugal Pump

The aim of this study was to assess platelet dysfunction and damage to organs after extracorporeal circulation using a pump based on a new method that adds a pulsatile flow to the continuous flow provided by a centrifugal pump. The continuous component of the total flow (2–3 L/min) is created by a Bio‐Pump centrifugal pump, while the pulsatile component is created by the pulsating of an inner membrane pneumatically controlled by an intra‐aortic counterpulsation balloon console (systolic volume of 37.5 mL in an asynchronous way with a frequency of 60 bpm). Six pigs were subjected to a partial cardiopulmonary bypass lasting 180 min and were sacrificed 60 min after extracorporeal circulation was suspended. The hematological study included the measurement of hematocrit, hemoglobin, leukocytes, and platelet function. The new pump did not significantly alter either platelet count or platelet function. In contrast, hematocrit and hemoglobin were significantly reduced during extracorporeal circulation (approximately 5% P = 0.011, and 2 g/dL P = 0.01, respectively). The leukocyte count during extracorporeal circulation showed a tendency to decrease, but this was not significant. In general, the short‐term use of the new pump (4 h) did not cause any serious morphological damage to the heart, lung, kidney, or liver. The results suggest that the hemodynamic performance of the new pump is similar to a conventional centrifugal pump and could therefore be appropriate for use in extracorporeal circulation.     

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.