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Extracorporeal Circuit (extracorporeal + circuit)
Selected AbstractsAnticoagulation Options for Pediatric HemodialysisHEMODIALYSIS INTERNATIONAL, Issue 2 2003Andrew Davenport Blood coagulation in the extracorporeal hemodialysis circuit is one of the manifestations of bio-incompatibility that is related to the activation of monocytes, platelets, and the coagulation cascades. Compared to adults, in pediatric patients, the surface area of the extracorporeal circuit is increased relative to blood volume. This is due to the patient's smaller blood volume and the combination of the higher relative surface area of the dialyzer, smaller lumen lines, and small-bore vascular catheters, potentially increasing contact activation of coagulation proteins, platelets, and inflammatory cells. Although unfractionated heparin remains the most commonly used anticoagulant, low molecular weight heparin offers the advantages of a single bolus, less fibrin and platelet deposition in the dialyzer, and perhaps more importantly, less osteoporosis, hyperkalemia, and abnormal lipoprotein profile. Although regional anticoagulants are available, these are often prohibitively expensive or require increased complexity of the dialysis procedure (e.g., citrate), but have the advantage of reducing the risk of bleeding when compared to heparin. Thrombin inhibitors are now available, and with the advent of argatroban, which is metabolized in the liver, have become the anticoagulants of choice for the few patients who develop heparin-induced thrombocytopenia type II. [source] Temperature and Thermal Balance Monitoring and Control in DialysisHEMODIALYSIS INTERNATIONAL, Issue 2 2003Franti, ek Lopot Temperature and thermal balance have been studied in an effort to explain better tolerance of ultrafiltration during isolated ultrafiltration and other convective techniques as compared to conventional hemodialysis. The large number of published studies has led to the conclusion that negative thermal balance of the extracorporeal circuit ameliorates hemodynamic stability by increased vasoreactivity and increased peripheral resistance. On the other hand, measurement of dialysis efficiency (urea removal) did not unequivocally confirm the theoretically predicted decrease in efficiency of "cool" dialysis. Another suggested application of temperature and thermal balance for assessing bioincompatibility is currently hampered by the ability of existing technology to evaluate thermal parameters of the extracorporeal circuit only. Publications on impact of negative thermal balance of the extracorporeal circuit on ultrafiltration-induced changes in blood volume give contradictory results. Further studies are needed for elucidation of the impact of thermal balance on overall biological response to dialysis. [source] Review article: Low-molecular-weight heparin as an alternative anticoagulant to unfractionated heparin for routine outpatient haemodialysis treatmentsNEPHROLOGY, Issue 5 2009ANDREW DAVENPORT SUMMARY Unfractionated heparin is currently the most widely used anticoagulant for outpatient haemodialysis. However, unfractionated heparin is a series of molecules, and as such has variable pharmacodynamics. Low-molecular-weight heparins were developed to improve both drug pharmacokinetic and dynamics, so to provide a reliable predictable clinical effect. The low-molecular-weight heparins are potent agents, but have an increased half-life compared with unfractionated heparin, and also require specialist laboratory monitoring. Despite these apparent drawbacks, low-molecular-weight heparins have become the anticoagulants of choice in Western Europe for routine outpatient haemodialysis sessions, due to the reliability of their clinical effect, and ease of administration, coupled with cost reduction. In standard clinical practice laboratory monitoring is not routinely performed, with drug dosing assessed by clinical inspection of the extracorporeal circuit, and the time for fistula needle sites to stop bleeding. [source] Effect of Hepatic Artery Flow on Bile Secretory Function After Cold IschemiaAMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2003David P. Foley These studies evaluated the influence of hepatic arterial flow on biliary secretion after cold ischemia. Preparation of livers for transplantation or hepatic support impairs biliary secretion. The earliest indication of cold preservation injury during reperfusion is circulatory function. Arterial flow at this time may be critical for bile secretion. Porcine livers were isolated, maintained at 4° for 2 h and connected in an extracorporeal circuit to an anesthetized normal pig. The extracorporeal livers were perfused either by both the hepatic artery and portal vein (dual) or by the portal vein alone (single). Incremental doses of sodium taurocholate were infused into the portal vein of both the dual and single perfused livers, and the bile secretion was compared. Most endogenous bile acids are lost during hepatic isolation. After supplementation, the biliary secretion of phosphatidyl choline and cholesterol was significantly better in the dual than single vessel-perfused livers; however, no difference was seen in bilirubin output. Single perfused livers were completely unable to increase biliary cholesterol in response to bile acid. The dependence of bile cholesterol secretion on arterial flow indicates the importance of this flow to the detoxification of compounds dependent on phosphatidyl choline transport during early transplantation. [source] rFV11a and paediatric open-heart surgery: thrombosis in the cardiopulmonary bypass circuit in spite of adequate markers of anticoagulationANAESTHESIA, Issue 6 2009N. A. Chambers Summary Recombinant activated factor V11 (rFV11a) is a relatively new procoagulant agent and its place in surgical practice continues to be investigated. We report the use of rFV11a to help manage bleeding in the operating theatre in a neonate, following weaning from cardiopulmonary bypass for arterial switch procedure, when bleeding continued in spite of maximal medical therapy and apparent exclusion of a surgical cause of bleeding. In this patient administration of rFV11a failed to facilitate haemostasis and cardiopulmonary bypass was re-instituted allowing location and repair of a small awkward surgical source. Separation from this additional 20 min of bypass was successful but a large thrombus was noted in the membrane oxygenator of the extracorporeal circuit in spite of the presence of adequate ,laboratory' markers of anticoagulation in the pump blood. No adverse sequelae to the patient occurred. [source] Optimizing the Circuit of a Pulsatile Extracorporeal Life Support System in Terms of Energy Equivalent Pressure and Surplus Hemodynamic EnergyARTIFICIAL ORGANS, Issue 11 2009Choon Hak Lim Abstract:, The nonpulsatile blood flow obtained using standard cardiopulmonary bypass (CPB) circuits is still generally considered an acceptable, nonphysiologic compromise with few disadvantages. However, numerous reports have concluded that pulsatile perfusion during CPB achieves better multiorgan response postoperatively. Furthermore, pulsatile flow during CPB has been consistently recommended in pediatric and high-risk patients. However, most (80%) of the total hemodynamic energy generated by a pulsatile pump is absorbed by the components of the extracorporeal circuit and only a small portion of the pulsatile energy is delivered to the patient. Therefore, we considered that optimizations of CPB unit and extracorporeal life support (ECLS) system circuit components were needed to deliver sufficient pulsatile flow. In addition, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy, calculated using pressure and flow waveforms, were used to evaluate the pulsatilities of pulsatile CPB and ECLS systems. [source] Clinical Real-Time Monitoring of Gaseous Microemboli in Pediatric Cardiopulmonary BypassARTIFICIAL ORGANS, Issue 11 2009Shigang Wang Abstract We describe the occurrence and distribution of gaseous microemboli with real-time monitoring in a pediatric cardiopulmonary bypass (CPB) circuit and in the cerebral circulation of patients using the Emboli Detection and Classification (EDAC) system and transcranial Doppler (TCD). Four patients (weights 3.2,13.8 kg) were studied. EDAC monitors were located on the venous line and on the postfilter arterial line to measure gaseous microemboli in the CPB circuit. TCD was used to measure high-intensity transient signals (HITS) in the middle cerebral artery. Before the initiation of CPB, EDAC detected gaseous microemboli in two cases when giving volume through the arterial line. At the initiation of CPB, gross air appeared in the venous line and gaseous microemboli were detected in the arterial line in all patients. EDAC detected a total of 3192,14 699 gaseous microemboli in the arterial line during the whole CPB period, more than 99% of which were smaller than 40 microns. After cessation of CPB, EDAC detected gaseous microemboli in the arterial line in all cases. The TCD detected HITS in two cases (25 and 315), and detected no HITS in two cases. We observed that the venous line acted as a principal source of gaseous microemboli, particularly when using vacuum-assisted venous drainage, and that a significant number of these gaseous microemboli smaller than 40 microns were subsequently transferred to the patient. Using EDAC and TCD together could strengthen the monitoring of gaseous microemboli in the extracorporeal circuit and cerebral circulation. [source] DALI Apheresis in Hyperlipidemic Patients: Biocompatibility, Efficacy, and Selectivity of Direct Adsorption of Lipoproteins from Whole BloodARTIFICIAL ORGANS, Issue 2 2000T. Bosch Abstract: Recently, the first apheresis technique for direct adsorption of low-density lipoprotein (LDL) and lipoprotein(a) [Lp(a)] from whole blood (DALI) was developed that does not require a prior plasma separation. That markedly simplifies the extracorporeal circuit. The aim of the present study was to test the acute biocompatibility, efficacy, and selectivity of DALI apheresis. In a prospective clinical study, 6 hypercholesterolemic patients suffering from angiographically proven atherosclerosis were treated 4 times each by DALI. 1.3 patient blood volumes were treated per session at blood flow rates of 60,80 ml/min using 750 or 1,000 ml of polyacrylate/polyacrylamide adsorber gel. The anticoagulation consisted of an initial heparin bolus followed by a citrate infusion. The sessions were clinically essentially uneventful. Mean corrected reductions of lipoproteins amounted to 65% for LDL-cholesterol, 54% for Lp(a), 28% for triglycerides, 1% for HDL-cholesterol, and 8% for fibrinogen. The selectivity of lipoprotein removal was high. Cell counts remained virtually unchanged and no signs of hemolysis or clotting were detected. Cell activation parameters elastase, ,-thromboglobulin, interleukin-1,, and IL-6 showed no significant increase. Complement activation was negligible. There was significant, but clinically asymptomatic, bradykinin activation in the adsorber with mean maxima of 12,000 pg/ml in the efferent line at 1,000 ml of treated blood volume. In conclusion, DALI proved to be safe, selective, and efficient for the adsorption of LDL-C and Lp(a), which simplifies substantially the extracorporeal therapy in hypercholesterolemic patients. [source] Fluid shifts during cardiopulmonary bypass with special reference to the effects of hypothermiaBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000J. K. Heltne Background Generalized overhydration, oedema and organ dysfunction occurs in patients undergoing open heart surgery using cardiopulmonary bypass (CPB) and hypothermia. Inflammatory reactions induced by contact between blood and the foreign surfaces of the extracorporeal circuit are commonly held responsible for the disturbances in fluid balance (,capillary leak syndrome'). Using the CPB circuit reservoir as a fluid gauge (measuring continuous extracorporeal blood volume), fluid shifts between the intravascular and the extravascular space, and differences between normothermic and moderately hypothermic CPB, were examined. Methods Piglets were placed on CPB (thoracotomy) under general anaesthesia. In the normothermic group (n = 7) the core temperature was kept at 38°C before and during 2 h on CPB, whereas in the hypothermic group (n = 7) the temperature was lowered to 29°C during bypass. In addition to accurate recording of fluid during operation, the extracorporeal blood volume was kept constant by maintaining a certain blood level in the CPB circuit's reservoir. Acetated Ringer was used as priming solution in the CPB, as maintenance fluid and for adding fluid to the reservoir if necessary. Results Cardiac output, serum electrolytes and arterial blood gases were all similar in the two groups. Haematocrit fell significantly following the start of CPB in both groups. The reservoir fluid level fell markedly in both groups necessitating fluid supplementation. This extra fluid requirement was transient in the normothermic group, but persisted in hypothermic animals. At the end of 2 h of CPB the hypothermic animals had received seven times more extra fluid than the normothermic pigs. Conclusion There were strong indications of a greater fluid extravasation induced by hypothermia. The model described, using the PBC circuit reservoir as a fluid gauge, provides the opportunity for further study of fluid volume shifts, their causes and potential ways to manipulate fluid pathophysiology related to hypothermia and to PBC. © 2000 British Journal of Surgery Society Ltd [source] | ||||||||||