Reliable long-term non-pulsatile circulatory support without anticoagulation
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The Terumo implantable left ventricular assist system (T-ILVAS) consists of a titanium centrifugal pump with a unique magnetically suspended impeller producing continuous (non-pulsatile) flow up to 10 l/min. The interior surface is heparin-coated and there is no purge system. We implanted the device into six sheep to ascertain in-vivo haemodynamic function, mechanical reliability and biocompatibility.The T-ILVAS was implanted via left thoracotomy without cardiopulmonary bypass. The inflow cannula was placed in the left ventricular apex and a Dacron outflow graft anastomosed to the descending aorta. All animals recovered well. No anticoagulation (heparin or warfarin) was given after the surgery. Suspension position, motor current, impeller speed and pump flow were continuously monitored and stored by on-line computer. Serial blood samples were collected to determine haematological and biochemical indices of renal function, liver function and haemolysis. All animals were electively euthanized between 3 and 7 months postoperatively. The explanted pumps were examined for mechanical reliability and thrombus formation. Major organs were examined macroscopically and histologically for thromboembolism.All animals appeared completely normal for up to 210 days. At speeds between 1500 and 2000 rev./min the device pumped up to 8 l/min capturing all mitral flow. There were no major complications (pump failure, thromboembolism, haemorrhage, or driveline infection). Indices of haemolysis, liver and renal function remained within normal limits. All pumps were mechanically sound and free from thrombus. One embolus was found in a sectioned kidney.The T-ILVAS successfully supported the systemic circulation without anticoagulation for up to 210 days. Mechanical reliability and biocompatibility were demonstrated. Organ function remained within normal limits during continuous non-pulsatile flow.Keywords:
Pulsatile flow
Peristaltic pump
Haemolysis
Extracorporeal circulation
Descending aorta
For the purpose of understanding the mechansim of haemolysis caused by various substances, the comparison of haemolytic action of various substances was carried out from the relation between the concentrations of substances and the incubation time with red blood cell.The phenomenon of haemolysis caused by various substances could be divided into two groups. The first group is haemolysis produced by the substances such as surface detergent, alcohols, urea and tauroglycocholate, and the difference between the concentra-tion producing complete haemolysis and that causing scarce haemolysis is very narrow. Haemolysis of the second group shows a very wide range of concentration, and is pro-duced by metals and organometallic compounds. The difference of mechanism of haemolysis caused by thosetwo groups was discussed.The comparison of haemolytic action by chemical compounds having similarstructure was also studied.
Haemolysis
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C3-independent immune haemolysis was studied using EAC14oxy2 cells and purified C5, C6, C7, C8 and C9. We have found that EAC14oxy2 cells were lysed by C5-C9 and that haemolysis occurs, even after pretreatment of the cells and the C5-C9 preparation with anti-C3. This indicates that EAC14oxy2 can be lysed by C5-C9 without any participation of C3. In contrast, EAC1 and EAC14 cells are not lysed by C5-C9, suggesting that our C5-C9 preparation lacks activated complement components, such as C3bBb, C5b6 or C(56)a. Based on our study of the haemolysis of EAC14oxy2, we have determined that: (i) EAC14oxy2 cells are lysed by a preparation of C5, C6, C7, C8 and C9, but no lysis occurs when any one of these complement is absent, (ii) for significant haemolysis of EAC14oxy2, a higher concentration of C5 is necessary as compared to the C5 requirement when haemolysis occurs in the presence of C3, (iii) the degree of haemolysis is linearly related to the concentration of C5 and does not reach a plateau, despite the addition of as much as 3,200 U of C5, and (iv) the degree of haemolysis is linearly related to the concentration of cell bound C42. These observations suggest that, in the absence of C3, the C3 convertase C42 can activate C5 directly, resulting in the formation of the membrane attack complex, C5b-9.
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Background Although most studies have shown that little haemolysis is induced by infusion pumps, there are some notable exceptions. Only limited data are available on the actual infusion pumps that are most used in hospitals in Quebec and elsewhere, namely, the Infusomat ® Space (peristaltic), Plum A+™ (piston) and Colleague ® CXE (shuttle) pumps. Methods Haemolysis and potassium levels were compared before and after the use of the three different infusion pumps. Using 135 units of packed red blood cells ( RBC s) aged from 10 to 28 days, 27 measurements were taken for each pump at various flow rates (30, 60, 150, 300 and 450 ml/h) and were compared with measurements taken before using the pumps. The range of flow rates was chosen to cover those of paediatric and adult transfusions. Results The shuttle‐ and piston‐type pumps resulted in low haemolysis levels. The peristaltic‐type pump produced significantly more haemolysis, which worsened at low flow rates, but the absolute value of haemolysis remained within the range recommended by the regulatory agencies in North America and Europe. Approximately two‐thirds of the haemolysis produced by the peristaltic‐type pump seemed to be secondary to the use of an antisiphon valve ( ASV ) on the transfusion line recommended by the manufacturer. Potassium levels did not increase with the use of the pumps. Conclusion Modern infusion pumps widely used in hospitals in Quebec and elsewhere produce non‐threatening levels of haemolysis during the transfusion of packed RBC s aged from 10 to 28 days. ASV s appear to induce additional haemolysis, and we do not recommend using them for blood transfusion.
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Peristalsis
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Background: The pneumatic tube system (PTS) has been implicated in inducing haemolysis. It is not known whether certain sample types are more susceptible to haemolysis than others. We assessed the level of haemolysis in commonly used sample types in the clinical biochemistry department when transported through the PTS. Method: Blood was collected in pairs for different sample types and sent to the laboratory via the pneumatic tube or delivered by a porter. Haemolysis indices were measured spectrophotometrically and compared for each pair of sample type. Results: Our results suggest that plain serum samples are more susceptible to haemolysis than the other sample types when sent through our PTS ( P <0.0001). Compared with serum with gel samples, plain serum samples are more prone to haemolysis ( P <0.001). This suggests that gel may confer some protection against haemolysis. Conclusion: Different hospitals will have varying system configurations and use different sample types. We recommend that each hospital investigate their own system to assess whether haemolysis is a recurring problem in any of the sample types transported.
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Background The haemolysis level at the end of storage is a performance parameter for RBC preparations. In the evaluation of new devices or new processes for processing blood, it is relevant to evaluate whether the haemolysis is linked to (1) specific characteristics of the blood donor, or (2) the nature of the blood-processing methodologies. Materials and Methods As part of the validation of a new automated whole blood processing system compared to the current manual methods, randomized, paired crossover studies were conducted evaluating measures of blood component quality, including RBC haemolysis over 42 days of storage. Results The association between haemolysis and the individual subject was evaluated by modelling haemolysis with independent predictors of treatment (control and test processing) and leucocyte reduction as fixed factors with donor and laboratory as random effects in a mixed-effects anova model. It was found that the day 42 haemolysis values were strongly dependent on the donor subject, with an intraclass correlation coefficient of 0·81. Conclusions The data reported in this study suggest a link between the specific whole blood donor and the haemolysis levels observed in red-blood-cell units stored refrigerated for 42 days. Additional research to identify possible donor characteristics associated with haemolysis during storage is warranted.
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The presence of Listeria monocytogenes in enrichment media can be masked by faster growth of other Listeria spp. Therefore, enhanced haemolysis agar (EHA) is a good alternative for another isolation media, because the presence of a few L. monocytogenes colonies can be detected in a majority of colonies of other listeriae on the basis of haemolysis. In this study the haemolysis reaction in EHA was optimized. In a collaborative study using reference samples, no significant differences in counts on EHA, Palcam and Oxford agar were shown.
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Fifty-five patients with Indian childhood cirrhosis were investigated for the occurrence of haemolysis and for its possible underlying mechanisms. Increased haemolysis was present in 76% of patients, and was severe in 12%. The degree of anaemia was not always proportional to the severity of haemolysis. No single factor accounted for haemolysis. Evidence of hypersplenism was present in only 7 (13%) patients. The haemolysis appeared to be more severe in patients with advanced liver disease. Evidence for autoimmune haemolytic anaemia was found in 27% of patients. No relation was seen between the degree of haemolysis and hypercholesterolaemia. These findings are compared with those reported in adult patients with cirrhosis of the liver.
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Abstract: 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 acfual CPB conditions in animal.
Peristaltic pump
Heart-Lung Machine
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