A Novel Technique for Cardiopulmonary Bypass Using Vacuum System for Venous Drainage with Pressure Relief Valve: An Experimental Study

To decrease the circuit priming volume, develop safety, and simplify the equipment, a cardiopulmonary bypass (CPB) circuit using a vacuum suction venous drainage system with a pressure relief valve was developed. The efficacy of this vacuum system was compared to that of a conventional siphon system. The system contains a powerful vacuum generator and a pressure relief valve to keep the negative pressure constant when blood suction is used. Using 8 mongrel dogs, the feasibility and the efficacy of this CPB system was tested. The changes in the negative pressure in the reservoir were within 5 mm Hg whether the suction lines were switched on or off. In all animals the amount of blood in the venous reservoir was stable throughout bypass. The decrease of priming volume was from 725 ml (siphon system) to 250 ml (vacuum system). At the end of CPB, the levels of hemoglobin in the vacuum system were significantly higher than those in the siphon system. These results demonstrated that this vacuum drainage system can provide simplification and a miniaturization of the cardiopulmonary bypass circuit resulting in low hemodilution during CPB.     

Laboratory evaluation of a low prime closed-circuit cardiopulmonary bypass system

We have explored the potential advantages of a low prime closed-circuit cardiopulmonary bypass (CPB) system using a non-human primate model. Although manufacturers have reduced priming volumes in individual CPB components, the standard circuit volume remains high because of the tubing diameter and length necessary for gravity drainage. By replacing gravity drainage with the negative pressure generated by a centrifugal pump, we can realize significant tubing volume reduction. Closed-circuit bypass was conducted on 13 baboons ranging from 5-15 kg. The circuit consisted of a centrifugal pump, a hollow fiber oxygenator, and 1/4" arterial and venous tubing. The design of the circuit included the capacity to remove a limited amount of venous air. Circulatory arrest during deep hypothermia with volume displacement into a reservoir was also accomplished with this circuit. The potential benefits of this low prime closed-circuit bypass system include blood conservation and reduction in blood surface area contact. The future safe clinical use of this type of closed-circuit bypass for routine open heart surgery will depend upon the incorporation of a device in the venous line to remove air. This is the greatest threat to patient safety in a closed circuit system and its use for open chest surgery must wait until an efficient venous air elimination device is available.     

Bicarbonate buffered ultrafiltration leads to a physiologic priming solution in pediatric cardiac surgery

Pediatric cardiopulmonary bypass (CPB) involves a high ratio of priming blood volume to patient blood volume. The composition of packed red blood cells (RBCs) is very unphysiological in terms of acid-base, electrolyte and metabolite values. Therefore, we tested the hypothesis whether ultrafiltration of the prime and replacement with bicarbonate buffered hemofiltration solution (BB-HS) is sufficient for reducing the metabolic load and reaching a physiologic state. For planned surgery of congenital heart defects with cardiopulmonary bypass, 20 CPB circuits were primed with BB-HS, gelatin and 1 unit of RBCs. The fluid was hemofiltrated using an ultrahemofilter at 300 ml/min until approximately 1000 ml of ultrafiltrate was restored with BB-HS. Blood gas analyses were obtained from the priming blood, once before and once after bicarbonate buffered ultrafiltration (BBUF). The measured substrates decreased significantly (P<0.001) after BBUF (glucose from 13.0+/-2.6 to 6.3+/-1.0 and lactate from 3.8+/-1.5 to 2.3+/-1.0 mmol/l). Acid-base parameters increased (P<0.001) to normal or high normal values (pH from 7.01+/-0.09 to 7.68+/-0.12; HCO(3) from 12.1+/-2.4 to 25.4+/-3.6 mmol/l and BE from -15.4+/-3.6 to -0.8+/-3.7 mmol/l). Even the electrolytes sodium, potassium and calcium changed significantly (P<0.001) toward the physiologic range. BBUF is an efficient method of reducing the metabolic load of priming. After BBUF, even the electrolyte and acid-base balance reached a physiologic state, which is important for minimizing electrolyte and acid-base disturbances after initiation of CPB.     

The effects of heparin bound surface modification (Carmeda Bioactive Surface) on human platelet alterations during simulated extracorporeal circulation

To determine if treatment with covalently bound heparin (Carmeda Bioactive Surface (CBAS)) to the synthetic surface of the extracorporeal circuit (ECC) would alter the stereotypic pattern of adverse platelet alterations, 450 ml of heparinized blood (lU/ml) was recirculated at a flow rate of twice the circulating volume (L/min) for 2 hrs at 37 degrees C through either untreated (CONT,n=7) or treated (CBAS,n=7) circuits constructed of identical components including a pediatric (0.8m 2) reversed hollow fiber membrane oxygenator. In CONT circuits, platelet count maintained 88+1% (x+/-SEM) of its initial level in the circuit prime sample, dropped to 36+/-6% after 5 min, and returned to 56+/-2% following 2 hrs of ECC. In CBAS circuits, platelet count in the circuit prime sample demonstrated 90+/-4%, decreased to 68+/-10% after 5 min (p less than 0.05) and declined further to 45+/-5% after 2 hrs (NS). Although platelets from both groups retained reactivity to ADP after priming the circuit, only at 5 min of recirculation did CBAS circuits significantly preserve this responsiveness. In CONT circuits, baseline plasma levels of platelet factor 4 rose from 24+/-3 to 581+/-82 ng/ml in the primed circuit and continued to rise to 2933+/-276 ng/ml by 2 hrs of ECC. In contrast, CBAS circuits markedly reduced this release after 2 hrs (577+/-165 ng/ml). Furthermore by 2 hrs of ECC, plasma levels of thromboxane B 2 in the CBAS circuits were significantly reduced when compared to CONT circuits (3035+/-1529 vs 29916+/-16293 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Residual blood in neonatal oxygenators after drainage.

The objective of this investigation was to measure the quantity of residual blood remaining in neonatal cardiopulmonary bypass (CPB) circuits after they had been drained and to assess the overall significance with regards to total patient blood volume. The residual blood volume left in three infant/neonatal CPB circuits-Medtronic Minimax 3381 (Group MM; n = 5), Polystan Safe Micro (Group SM; n = 6), and Terumo Capiox 308 (Group CX; n = 3)--after they had been drained was determined. This was done by using an electronic scale to weigh the circuit before setup and after CPB when all possible blood was recovered from it. Total priming volume, estimated patient blood volume, residual blood volume, surgical blood loss in theater, and autogeneic blood usage were recorded in each case. Mean residual blood volumes measured were MM = 161 ml (SD 27 ml), SM = 103 ml (SD 19 ml), and CX = 133 ml (SD 15 ml). These volumes were significant, because calculations show that the volume of red cells lost in the circuit is equivalent to fourteen percent of the total patient blood volume. In view of this, neonatal oxygenator design should be minimized to reduce the priming volume and more consideration should be given to ease of residual blood recovery.     

Transfusion-free cardiopulmonary bypass in Jehovah's Witness patients weighing less than 5 kg

Performing cardiac surgery on pediatric Jehovah's Witness patients is a great challenge for the surgical team and especially for the perfusionist. Jehovah's Witnesses reject blood transfusions on the grounds of their literal interpretation of passages of the Bible. In accordance with this belief, Jehovah's Witnesses feel that it is also forbidden to retransfuse autologous blood that has been separated from their own circulatory system. We report the use of cardiopulmonary bypass (CPB) during open-heart surgery in three infants with a body weight of 4.5 kg, 3.5 kg, and 3.1 kg, respectively, without transfusion of blood components. A small-volume CPB circuit with a priming volume of 200 mL, including the arterial line filter, was designed to decrease the degree of hemodilution. A dedicated pediatric heart lung machine console with remote pump heads and intensive blood conservation efforts allowed the operation without the use of donor blood. The CPB circuits were primed with crystalloid solution only. The procedures were performed in normothermia or in moderate hypothermia. Pre-CPB hemoglobin levels were 10.8 g/dL, 10.6 g/dL, and 8.5 g/dL. The hemoglobin concentrations measured during CPB ranged from 5.9 to 6.5 g/dL, 6.4 to 6.8 g/dL, and 5.5 to 5.9 g/dL, respectively. The patients did not receive any blood or blood products during their entire hospital stay.     

Rat cardiopulmonary bypass model: application of a miniature extracorporeal circuit composed of asanguinous prime

A clinically relevant rat cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. Previous rat CPB models have been described in the literature; however, they have many limitations, including large circuit surface area, the inability to achieve full bypass, and donor blood requirements for prime. Therefore, we have established a rat CPB model designed to overcome these limitations. The miniature circuit consisted of a filtered reservoir, heat exchanger, membrane oxygenator (surface area = 0.02 m2) with a static priming volume of 2.8 mL, and an inline blood gas monitor. The circuit was primed with 9.5+/-0.5 mL of crystalloid solution and CPB was established on male Sprague-Dawley rats (430-475 g, n = 5) by cannulating the left common carotid artery and the right external jugular vein. The animals were placed on CPB at full flow (111+/-13 mL/kg/ min) for 1 hour and were monitored for and additional 2 hours after the CPB procedure. Hemodynamics, hemoglobin concentration (Hb), and blood gases were analyzed at three time intervals: before, during, and after CPB. The circuit performance was evaluated according to prime volume, compliance, hemodynamic parameters, and gas and heat exchange as described by modified AMMI standards. Data are expressed as mean+/-SD and a repeated-measures analysis of variance with post-Hoc test was used for data comparison between the three time intervals. The ratio of oxygenator surface area to subject body weight for this model is comparable with that of current human adult CPB practice (0.05 m2/kg vs 0.057 m2/kg) Full CPB was achieved and we observed clinically acceptable PaO2, PaCO2, and SvO2 values (209+/-86 mmHg, 25+/-2 mmHg, 78+/-8%, respectively) while on CPB. The use of asanguinous prime did produce statistically significant Hg reduction (15.7+/-0.76 vs. 9.2+/-0.59 g/dL) comparable with clinical practice. No statistically significant differences between pre- and post-CPB hemodynamics and blood gases were found in our study. We have established a miniature circuit consisting of asanquineous prime for a rat CPB model that maintains clinically acceptable results regarding hemodynamic parameters, blood gases, and hemodilution. This model would be valuable for further use in clinically relevant research studies.     

Experimental use of an ultra-low prime neonatal cardiopulmonary bypass circuit utilizing vacuum-assisted venous drainage.

In adult cardiopulmonary bypass surgery, vacuum assisted venous drainage has become a popular technique to augment venous return to the bypass circuit. The application of this technique in neonatal cardiopulmonary bypass surgery could be beneficial to the further miniaturization of neonatal circuitry by coupling radical respositioning of the oxygenator and pump console with decreasing line length. This report communicates the use of an investigational, vacuum assisted venous drainage neonatal circuit that is positioned at patient level utilizing a modified pump console with elevated double head twin roller pumps. The circuit, including the oxygenator, arterial line, venous line, raceway tubing, and a functional level in the venous reservoir has a priming volume of 107 ml. Initial bench and animal tests have demonstrated that this technique may be clinically feasible in CPB applications. With vacuum assisted venous drainage, the goal of asanguinous neonatal cardiac surgery could become a reality. Safety issues must be adequately addressed to ensure that this technique does not impose unacceptable risks.     

Vacuum-assisted venous drainage: to air or not to air, that is the question. Has the bubble burst?

Assisted venous drainage is a recent development in cardiopulmonary bypass (CPB) and was introduced to overcome limitations in achieving adequate blood flow through small diameter cannulas used in minimally invasive surgery. The more common application, vacuum assisted venous drainage (VAVD) is now widely used in both adult and pediatric CPB. During a clinical investigation into pharmacological cerebral protection at Green Lane Hospital, we repeatedly observed evidence of emboli in the right common carotid artery following both entrainment of air into the venous line, and also, reductions in the blood level of the hard-shell venous reservior. We subsequently embarked upon a series of in vitro experiments designed to identify sources of emboli from the CPB circuit, and to evaluate the ability of CPB circuit components to remove air entrained into the venous line under conditions of both gravity and vacuum assisted venous drainage. Initial experiments revealed design features of certain hard-shell venous reservoirs that generated gaseous emboli. In further studies using adult circuits, entrainment of air into the venous line under conditions of conventional gravity venous drainage resulted in emboli distal to the arterial filter. When these studies were repeated using VAVD, arterial line emboli increased eight to tenfold. Initial experiments with a pediatric circuit showed similar findings. Cerebral emboli during CPB have been positively correlated with increasing neurocognitive deficits. The application of VAVD has been employed clinically without any significant redesign of the components of the CPB circuit. While VAVD may be efficacious in certain scenarios, a thorough understanding of its influence on CPB is essential. Advantages must be balanced against potential hazards. The safe use of VAVD necessitates refinement of perfusion techniques, judicious choice of application, and further development of the CPB circuit.     

Binding of fentanyl and alfentanil to the extracorporeal circuit

Adsorption of fentanyl and alfentanil to the cardiopulmonary bypass (CPB) equipment was studied in vitro by adding one of the analgesics to the priming solution consisting of either saline or a mixture of saline and blood. Opiate concentrations in the solutions were measured during a 60-min circulation period of a closed CPB system. When the saline prime was used, 29% of the predicted fentanyl level of 30 ng ml-1 was found at the end of the experiment, while the recovery of alfentanil was 80% of the calculated level of 1500 ng ml-1. When blood was added to the prime, experiments with fentanyl produced similar results to those with pure saline prime, but recovery exceeding the calculated concentration was obtained with alfentanil. The difference between the alfentanil levels in the two primes may reflect the poor distribution of this analgesic into red blood cells. In another set of experiments, the CPB circuit was primed with fentanyl or alfentanil and circulated for 10 min before connection of the apparatus to patients undergoing cardiac surgery under high-dose opiate anaesthesia. This priming prevented the steep reduction in plasma opiate concentration regularly observed during the institution of CPB. It is concluded that in a clinically relevant dose range a smaller fraction of alfentanil is sequestered by the CPB apparatus than fentanyl.     

The effectiveness of low-prime cardiopulmonary bypass circuits at removing gaseous emboli

During extracorporeal circulation, the patient's blood is siphoned into the extracorporeal circuit (ECC) by gravity or may be assisted kinetically or by vacuum. In all instances, negative pressure is generated in the venous line, which can cause entrainment of air into the ECC at the cannulation site. The typical ECC uses a venous reservoir, membrane oxygenator, and arterial line filter, which together aid in removal of air that has entered the venous line and minimize the transmission of gaseous microemboli to the patient. Recently, several manufacturers have introduced low prime ECCs with component configurations that differ from conventional ECCs, including the omission of a venous reservoir. These configuration changes may change the ability of the circuit to handle air and therefore their ability to minimize gaseous microemboli. The purpose of this study was to test the ability of new low prime ECCs to remove air introduced into the venous line and minimize gaseous microemboli from entering the patient's circulation. Using a model of CPB, air was introduced into the venous line of a low prime ECC and a conventional CPB circuit. The detection of the gaseous microemboli produced was monitored distal to the oxygenator by an ultrasonic emboli detector to determine if venous air was able to traverse the ECC at varying rates of air introduction and blood flow. Data was collected using data acquisition software loaded on a personal computer. Gaseous microemboli levels detected in the arterial line of the low prime ECC were 8 to 10 times higher than the microemboli levels detected in the conventional ECC at all blood flow rates. Every effort should be made to minimize and prevent air from being entrained in the venous line of a low prime CPB circuit to minimize the risk of arterial gaseous microemboli generation.     

A volume-variable reservoir-pump for a manually operated cardiopulmonary bypass circuit for emergency]

We developed a manually operated portable cardiopulmonary bypass circuit for resuscitation. The circuit is composed of, in turn, a venous drainage catheter, one-way valve, self-inflating reservoir, one-way valve, artificial lung, and an arterial catheter. These components are interlocked with conducting tubes with quick connectors. The priming volume of the circuit is about 300 ml including the self-inflating reservoir of 120 ml in capacity. For a patient with small stature, stroke volume is easily controlled by changing manual compression of the reservoir, but dilution of circulating blood with the priming solution is inevitable. For a controllable reduction of the reservoir volume, we incorporated a thin-walled balloon, which is inflatable from the outside, into the room of the reservoir. If the balloon is inflated with some amount of liquid, the same volume of functional capacity of the reservoir is lost. Thus the reservoir volume is adjusted, the hemodilution with a priming solution is minimized, and an excessive stroke volume with an inadvertent compression of the reservoir-pump is prevented as well. This innovation will make our standard size bypass circuit applicable to almost all patients, except for a newborn or infant who requires a special size of bypass circuit, and improve the survival rate of cardiopulmonary resuscitation.     

Evaluation of Hemodynamic Performance of a Combined ECLS and CRRT Circuit in Seven Positions With a Simulated Neonatal Patient

As it is common for patients treated with extracorporeal life support (ECLS) to subsequently require continuous renal replacement therapy (CRRT), and neonatal patients encounter limitations due to lack of access points, inclusion of CRRT in the ECLS circuit could provide advanced treatment for this population. The objective of this study was to evaluate an alternative neonatal ECLS circuit containing either a Maquet RotaFlow centrifugal pump or Maquet HL20 roller pump with one of seven configurations of CRRT using the Prismaflex 2000 System. All ECLS circuit setups included a Quadrox‐iD Pediatric diffusion membrane oxygenator, a Better Bladder, an 8‐Fr arterial cannula, a 10‐Fr venous cannula, and 6 feet of ¼‐inch diameter arterial and venous tubing. The circuit was primed with lactated Ringer's solution and packed human red blood cells resulting in a total priming volume of 700 mL for both the circuit and the 3‐kg pseudopatient. Hemodynamic data were recorded for ECLS flow rates of 200, 400, and 600 mL/min and a CRRT flow rate of 50 mL/min. When a centrifugal pump is used, the hemodynamic performance of any combined ECLS and CRRT circuit was not significantly different than that of the circuit without CRRT, thus any configuration could potentially be used. However, introduction of CRRT to a circuit containing a roller pump does affect performance properties for some CRRT positions. The circuits with CRRT positions B and G demonstrated decreased total hemodynamic energy (THE) levels at the post‐arterial cannula site, while positions D and E demonstrated increased post‐arterial cannula THE levels compared to the circuit without CRRT. CRRT positions A, C, and F did not have significant changes with respect to pre‐arterial cannula flow and THE levels, compared to the circuit without CRRT. Considering hemodynamic performance, for neonatal combined extracorporeal membrane oxygenation (ECMO) and CRRT circuits with both blood pumps, we recommend the use of CRRT position A due to its hemodynamic similarities to the ECMO circuit without CRRT.     

Air Removal Efficiency of a Venous Bubble Trap in a Minimal Extracorporeal Circuit During Coronary Artery Bypass Grafting

The use of minimized extracorporeal circuits (MECC) in cardiac surgery is expanding. These circuits eliminate volume storage and bubble trap reservoirs to minimize the circuit. However, this may increase the risk of gaseous micro emboli (GME). To reduce this risk, a venous bubble trap was designed. This study was performed to evaluate if incorporation of a venous bubble trap in a MECC system as compared to our standard minimized extracorporeal circuit without venous bubble trap reduces gaseous micro emboli during cardiopulmonary bypass (CPB). Forty patients were randomly assigned to be perfused either with or without an integrated venous bubble trap. After preliminary evaluation of the data of 23 patients, the study was terminated prior to study completion. The quantity and volume of GME were significantly lower in patients perfused with a venous bubble trap compared to patients perfused without a venous bubble trap. The present study demonstrates that a MECC system with a venous bubble trap significantly reduces the volume of GME and strongly reduces the quantity of large GME (>500 µm). Therefore, the use of a venous bubble trap in a MECC system is warranted.     

A Low‐Cost,Small Volume Circuit for Autologous Blood Normothermic Perfusion of Rabbit Organs

We have designed a laboratory extracorporeal normothermic blood perfusion system for whole organs (e.g., kidney) that achieves pulsatile flow, low levels of hemolysis, and a blood priming volume of 60 mL or less. Using this uniquely designed extracorporeal circuit, we have achieved perfusion of two isolated ex vivo constructs. In the first experiment, we successfully perfused a rabbit epigastric flap based on the femoral vessels. In the second experiment, we were able to perfuse the isolated rabbit kidney for 48 h (range for all kidneys was 12–48 h) with excellent urine output, normal arterial blood gasses at 24 h, and normal ex vivo kidney histology at the conclusion of the experiments. These parameters have not been achieved before with any known or previously published laboratory extracorporeal circuits. The study has implications for prolonged organ perfusion prior to transplantation and for tissue engineering of vascularized tissues, such as by the perfusion of decellularized organs.     

A simplified method for autoregulation of blood flow in the extracorporeal membrane oxygenation circuit

The ability of autoregulate blood flow in the extracorporeal membrane oxygenation (ECMO) circuit is critical to prevent cavitation and air embolism. Conventional circuits have used a spring-loaded mechanical switching device that interrupts the flow of power to the roller head when falling venous return collapses the venous bladder. This device has been less than desirable due to being poorly adjustable, subject to sporadic flow in periods of hypovolemia, and not commercially available. An improved alternative is reported using a commercially available pressure monitor and computerized switching device, which, when attached to the venous reservoir or bladder, has the ability to autoregulate blood flow in the ECMO circuit by smoothly regulating the roller head velocity. Experience with this system in the laboratory employing a swine model, and in 35 infants, is reported without device-related complications.     

A perfluorocarbon emulsion prime additive improves the electroencephalogram and cerebral blood flow at the initiation of cardiopulmonary bypass

Depression in electroencephalogram (EEG) has been documented clinically and is reproducible in swine at the initiation of cardiopulmonary bypass (CPB) utilizing a crystalloid prime. The physiological cause of this transient alteration in electrical brain activity appears to be associated with the transient drop in arterial pressure. The etiology is unknown but may be attributable to the bolus of the crystalloid prime or micro emboli, either air or fibrin-platelet. Thirteen swine (17-26 kg) were anesthetized and received 4 mg/kg dexamethasone, and following a tracheotomy were ventilated with halothane in 100% O2. Surgical preparation included: sternotomy and preparation for right atrial-aortic CPB. The CPB circuit consisted of a hollow fiber membrane oxygenator, a hard-shell venous reservoir, a roller pump, and PVC tubing. The circuit was randomly primed with either 1200 ml Plasmalyte-A or 10 ml/kg perfluorocarbon emulsion (PFE) and Plasmalyte-A to total 1200 ml. The animals were monitored continuously for systemic hemodynamics and electrocardiogram, and cerebral monitoring included blood flow and bitemporal EEG. Arterial blood gases were measured and PaCO2 was kept between 30-45 mmHg both before and during CPB. Cerebral blood flow (CBF) was measured pre-CPB and at 10 minutes after initiation of CPB. Bitemporal computerized EEG was analyzed every 60 seconds. Total power of each hemisphere, power in frequency bands, and spectral edge were recorded. All animals demonstrated a relative decrease in EEG total power at the onset of CPB. Animals that received PFE demonstrated a more stable arterial blood pressure, an increased CBF, and a lesser decrease and an earlier recovery of the EEG power.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extraction of bisphenol-A from a cardiopulmonary bypass circuit

We measured levels of bisphenol-A (BPA) in a priming solution and blood of a cardiopulmonary bypass (CPB) circuit. Eight circuits were used in the study of a priming solution. Blood samples were obtained from 6 patients who underwent open heart surgery after the commencement of CPB and at the termination of CPB. Another 3 samples were collected directly from the saline in a polyethylene container as a control. Then the concentrations of BPA in them were determined by means of gas chromatography. No detectable BPA was found in controls. However, a small amount was detected in the saline from the circuits (0.9 +/- 1.1 micrograms/l). A very small amount was also detected in the blood after the commencement and at the termination of CPB (0.3 +/- 0.2 microgram/l, and 0.4 +/- 0.3 microgram/l, respectively). BPA was considered to be leached from the circuit to the priming solution and the blood because the parts of the reservoir and the oxygenator were made of polycarbonate containing BPA. We suppose the BPA concentration is probably at a safe level. However, the data on the endocrinologically toxic level of blood BPA are insufficient. Therefore, the use of plastic in a circuit may require closer scrutiny to determine whether BPA contributes to exposure to xenoestrogens.     

Comparison of Two Miniaturized Cardiopulmonary Bypass Systems Regarding Inflammatory Response

Cardiopulmonary bypass (CPB) is a known mediator of systemic inflammatory response. Extracorporeal circulations are undergoing continuous modifications and optimizations to achieve better results. Hence we aim to compare the inflammatory response associated with two recent miniature extracorporeal circulation systems during normothermic CPB. We measured plasma levels of cytokines including interleukin (IL)‐1β, IL‐6, IL‐10, tumor necrosis factor‐α, migration inhibitory factor (MIF), receptor for advanced glycation endproduct, and cluster of differentiation 40 ligand in 60 consecutive patients during the first 24 h after CPB. The patients were prospectively randomized to one of three trial groups: patients in group A were operated with the minimal extracorporeal circulation circuit (MECC, Maquet, Rastatt, Germany), group B operated with the extracorporeal circulation circuit optimized (ECC.O, Sorin, Italy), and group C operated with a conventional extracorporeal circuit (CECC, Maquet). Arterial blood samples were collected at intervals before, 30 min after initiation, and after termination of CPB. Further samples were collected 6 and 24 h after CPB. IL‐10 levels were significantly raised in the CECC group as compared with either of the mini ECC‐circuits with a peak concentration at 6 h postoperatively. Human MIF concentrations were significantly higher in the CECC group starting 30 min after CPB and peaking at the end of CPB. The overall reduction in cytokine concentrations in the mini‐ECC groups correlated with a lower need for blood transfusion in MECC and a shorter mechanical ventilation time for ECC.O. Normothermic CPB using minimally invasive extracorporeal circulation circuits can reduce the inflammatory response as measured by cytokine levels, which may be beneficial for perioperative preservation of pulmonary function and hemostasis in low risk patients.     

Extraction of di-2-ethylhexyl phthalate from a cardiopulmonary bypass circuit]

We measured levels of di-2-ethylhexyl phthalate (DEHP) in a priming solution of a cardiopulmonary bypass circuit. The circuit consisted of a venous reservoir, an oxygenator, and polyvinyl chloride (PVC) tubes. Eight circuits were used in this study. In 4 circuits a heparin-coating PVC tube was used and, in the others, a non-coating PVC tube. After they were primed with 1,500 ml of saline, the saline was circulated for 30 minutes at a rate of 6 l/min at 42 degrees C. Another four samples were collected directly from the saline in a polyethylene container as a control. Then the concentrations of DEHP in them were determined by means of gas chromatography. No detectable DEHP was found in controls. But, a small amount was detected in the saline from the circuits (2.75 +/- 4.27 ppb, and 3.75 +/- 4.99 ppb, respectively). DEHP was considered to be leached from the circuit to the priming solution because the tubes were made of PVC containing DEHP as a plasticizer. We suppose the DEHP concentration is probably at a safe level. However, the data on the endocrinologically toxic level of blood DEHP are insufficient. Therefore, the use of plastic in a circuit may require closer scrutiny to determine whether DEHP leached from PVC contributes to exposure to xenoestrogens.