Priming Volume Research Articles

Integrated Oxygenator FX05

In recent years, there has been a trend to incorporate arterial filters into cardiopulmonary bypass (CPB) oxygenators. The FX oxygenators are the first examples of integrating a filter around the fibers of the oxygenator. To assess the efficacy of the FX05 oxygenator, in comparison with our existing CPB setup (RX05 oxygenator + arterial filter), we randomly assigned 40 patients undergoing CPB, with calculated flows <1.5 L/min, to FX05 or RX05 + arterial filter (19 FX and 21 RX). Embolic load was assessed using the emboli detection and classification quantifier, with sensors placed prefilter and postfilter/oxygenator at identical distances for both devices. A total of 6,270 FX readings and 6,183 RX readings were obtained. Because of the extremely skewed nature of the data, the prefilter embolic volumes were divided into deciles, and each decile was analyzed separately. Our results show that the devices perform similarly; both filter out a high percentage of the prefilter embolic load. Our data support that in the clinical setting, the FX05 is as effective at removing emboli as the RX05 with an arterial filter (CXAF02) which, in conjunction with the prime volume reduction and circuit simplification, has warranted our conversion to the FX series of oxygenators.

Abstract P77: Reduced Inflammatory Response with a Novel Cardiopulmonary Bypass Circuit: A Prospective Randomized Evaluation

BACKGROUND: The detrimental effects of inflammation following cardiopulmonary bypass (CPB) result in poor postoperative outcomes in patients undergoing heart surgery. A novel CPB circuit (Admiral, Eurosets, Italy) with its inner surface coated with a proprietary phosphorylcholine coating was hypothesized to elicit a reduced inflammatory response compared to a conventional CPB circuit. METHODS: Patients undergoing isolated aortic valve surgery were enrolled in a prospective study and either assigned to Admiral group (Admiral, n=15) or the conventional CPB group (Dideco, n=15). The Admiral oxygenator reduces priming volumes, decreases membrane surface area and incorporates a cell-saver selectively filtering the blood collected through mediastinal cavity before re-transfusion into the patient. The conventional CPB circuit used was a Dideco D903 Avant with an open cardiotomy reservoir. Clinical data and biochemical parameters were measured postoperatively, during CPB and at 1, 18, 36, 48 and 72 hours, respectively. RESULTS: Preoperative demographics such as age (68.2±10.4 vs. 70.9±10), Euroscore (6.8±2.3 vs. 6.2±1.1) as well as others did not differ between Admiral and Dideco groups, respectively. The CPB time (Admiral=104±30 vs. Dideco=99±17 minutes, p=NS), aortic cross clamp time (Admiral=73.2±17.5 vs. Dideco=73.8±19 minutes, p=NS) and the incidence of perioperative complications were also comparable. There was a significant decrease in the Admiral group with respect to inflammatory response, assessed by means of D-dimer (Admiral=1332.3±953.9 vs. Dideco=2791.9±1740.7, p=0.02), CRP (Admiral=169.1±164.8 vs. Dideco=57.1±39.3, p=0.04), IL-6 (Admiral=11.8±12.5 vs. Dideco=26.5±24.9, p=0.02) and TNF-a (Admiral=29±28.7 vs. Dideco=45.5±23.6, p=0.03). CONCLUSIONS: Although no considerable difference was detected in terms of peri-operative outcomes, the Admiral oxygenator did result in a significant reduction of inflammatory markers in immediately postoperative course primarily due to its enhanced biocompatibility. More powerful studies may yield potentially incremental benefits with Admiral oxygenator in future.

A novel wearable pump-lung device: In vitro and acute in vivo study

To provide long-term ambulatory cardiopulmonary and respiratory support for adult patients, a novel wearable artificial pump-lung device has been developed. The design features and in vitro and acute in vivo performance of this device are reported. This device features a uniquely designed hollow-fiber membrane bundle integrated with a magnetically levitated impeller that together form one ultracompact pump-lung device, which can be placed like current paracorporeal ventricular assist devices to allow ambulatory support. The device is 117 mm in length and 89 mm in diameter and has a priming volume of 115 ml. In vitro hydrodynamic, gas transfer and biocompatibility experiments were carried out in mock flow-loops using ovine blood. Acute in vivo characterization was conducted in an ovine model by surgically implanting the device between right atrium and pulmonary artery. The in vitro results show that the device with a membrane surface area of 0.8 m(2) was capable of pumping blood from 1 to 4 liters/min against a wide range of pressures and transferring oxygen at a rate of up to 180 ml/min at a blood flow of 3.5 liters/min. Standard hemolysis tests demonstrated low hemolysis at the targeted operating condition. The acute in vivo results also confirmed that the device can provide sufficient oxygen transfer with excellent biocompatibility. Based on in vitro and acute in vivo study findings, this highly integrated wearable pump-lung device can provide efficient respiratory support with good biocompatibility and it is ready for long-term evaluation.

Pediatric perfusion in Japan: 2010 practice survey

We report here Japan's first pediatric perfusion survey. It covers practices from January 2007 through December 2009. Of the 70 congenital heart centers contacted, 53 (76%) completed the survey. They reported performing 3,379 pediatric cardiopulmonary bypass (CPB) procedures in 2009, 3,408 in 2008, and 3,358 in 2007.Twenty-eight percent of all centers used CPB circuits with a priming volume between 151-200 ml. All centers used pre-bypass ultrafiltration and only 6% used retrograde autologous priming. A biomaterial-coated circuit was used by 78% of the centers, a roller pump as the arterial pump by 91%, vacuum-assisted venous drainage by 39%, dilutional ultrafiltration by 48%, and modified ultrafiltration at the end of the procedure by 30%. A regional oxygen saturation monitor was used by 69% of the centers and high flow (150-200 ml/kg/min) management with alpha-stat blood gas control was standard during moderate to normothermic CPBs. Crystalloid cardioplegia solution was used as myocardial protection by 56% of the centers, electronic recording of monitoring data by 51%. The centers performed 98 pediatric extracorporeal membrane oxygenation procedures in 2007, 109 in 2008, and 119 in 2009; 58% of the centers used a centrifugal pump. This survey provides a description of the current practice in Japan. Future surveys will identify trends and rate of change in practice.

Blood conservation strategies for emergency open cardiac surgery in a patient with anti-M.

Blood conservation strategies for emergency open cardiac surgery in a patient with anti-M.

In Vitro Evaluation of Gaseous Microemboli Handling of Cardiopulmonary Bypass Circuits with and without Integrated Arterial Line Filters

The delivery of gaseous microemboli (GME) by the cardiopulmonary bypass circuit should be minimized whenever possible. Innovations in components, such as the integration of arterial line filter (ALF) and ALFs with reduced priming volumes, have provided clinicians with circuit design options. However, before adopting these components clinically, their GME handling ability should be assessed. This study aims to compare the GME handling ability of different oxygenator/ALF combinations with our currently utilized combination. Five commercially available oxygenator/ALF combinations were evaluated in vitro: Terumo Capiox SX25RX and Dideco D734 (SX/ D734),Terumo Capiox RX25R and AF125 (RX/AF125),Terumo FX25R (FX), Sorin Synthesis with 102 μm reservoir filter (SYN102), and Sorin Synthesis with 40 μm reservoir filter (SYN40). GME handling was studied by introducing air into the venous return at 100 mL/min for 60 seconds under two flow/ pressure combinations : 3.5 L/min, 150 mmHg and 5 L/min, 200 mmHg. Emboli were measured at three positions in the circuit using the Emboli Detection and Classification (EDAC®) Quantifier and analyzed with the General Linear Model. All circuits significantly reduced GME. The SX/D734 and SYN40 circuits were most efficient in GME removal whilst the SYN102 handled embolic load (count and volume) least efficiently (p&lt; .001). A greater number of emboli &lt;70 μm were observed for the SYN102, FX and RX/AF125 circuits (p&lt; .001). An increase in embolic load occurred with higher flow/pressure in all circuits (p&lt; .001). The venous reservoir significantly influences embolic load delivered to the oxygenator (p&lt; .001). The majority of introduced venous air was removed; however, significant variation existed in the ability of the different circuits to handle GME. Venous reservoir design influenced the overall GME handling ability. GME removal was less efficient at higher flow and pressure, and for smaller sized emboli. The clinical significance of reducing GME requires further investigation.

Extracorporeal Life Support: Moving at the Speed of Light

Extracorporeal life support (ECLS), or extracorporeal membrane oxygenation (ECMO) as it is also known, has been used to support over 45,000 patients to date. Overall survival is 62%. After many years of no change in equipment and technology, there has been a recent flurry of new pumps, cannulas, and oxygenators available for ECLS use. While the impact of this new technology is not yet completely defined, initial results have found that these systems provide safe support with lower priming volumes and less bleeding complications. New cannulas are also available, some making it easier for venovenous support in patients, from infants through adults. The reported success of ECLS in patients with H1N1 during the 2009-2010 epidemic and the improved survival of patients randomized to the ECMO arm of a recently completed adult study of respiratory failure have also brought ECLS into the spotlight much more than other years. Whether these developments will usher in a new era of ECLS expansion to a wider range of patients will require close consideration and observation. Other areas that need to be further refined include anticoagulation management, treatment of bleeding complications, learning to "nurse" patients in an awake state, such as is done in some European (and a few United States) centers, and neurodevelopmental outcome on a long-term basis.

Microbubble Generation and Transmission of Medtronic’s Affinity Hardshell Venous Reservoir and Collapsible Venous Reservoir Bag: An In-Vitro Comparison

Microemboli are implicated in neurological injury; therefore, the extracorporeal circuit (ECC) should not generate microbubbles or transmit introduced air. The venous reservoir is the first component in the ECC designed to remove introduced air. The purpose of this study was to investigate the relative safety of two kinds of adult venous reservoirs—the closed soft-shell venous reservoir (SSVR [Medtronic CBMVR 1600]) and the open hard-shell venous reservoir (HSVR [Affinity NT CVR])—in terms of microbubble generation and introduced air transmission. A recirculating in-vitro circuit was used to compare the two reservoirs with the SSVR further assessed in a fully closed or partially open state. Microbubbles were counted using a Hatteland CMD10 Doppler in the outflow of the reservoirs before (microbubble generation) and after infusing 20 mL/min of air into the venous line (microbubble transmission) while altering pump flow rates (3 L/min; 5 L/min) and reservoir prime (200 mL; 700 mL). Negligible bubble generation was noted in the SSVRs at both flow rates and either reservoir volume. However, microbubble generation was significant in the HSVR at the higher flow rate of 5 L/min and lower reservoir volume of 200 mL. When infusing air, a flow of 3 L/min was associated with insignificant to small increases in microbubble transmission for all reservoirs. Conversely, infusing air while flowing at 5 L/min was associated with significantly more microbubble transmission for all reservoirs at both low and high reservoir volumes. The SSVR is as safe as the HSVR in microbubble handling as the generation and transmission of microbubbles by the SSVR is not more than the HSVR over a range of prime volumes and flow rates. As both reservoirs transmitted microbubbles at higher pump flow rates regardless of reservoir volumes, it is important to eliminate venous air entrainment during cardiopulmonary bypass.

Blood Utilization in Neonates and Infants Undergoing Cardiac Surgery Requiring Cardiopulmonary Bypass

Neonates and infants undergoing cardiac surgery with cardiopulmonary bypass are exposed to multiple blood products from different donors. The volume of the bypass circuit is often as large as the patient's total blood volume and asanguineous bypass primes are unusual. As a result, blood products are required for the cardiopulmonary bypass prime and are often used to treat the postbypass dilutional coagulopathy. We review clot formation and strength, cardiopulmonary bypass prime considerations, assessment of postbypass coagulopathy, component therapy use, ultrafiltration techniques, and use of antifibrinolytic medications. A combined approach including techniques to minimize the prime volume, utilization of ultrafiltration, administration of antifibrinolytics during surgery, and the proper treatment of the dilutional coagulopathy can limit the transfusion requirements.

A Technique for Autologous Priming of the Veno-Venous Bypass Circuit during Liver Transplantation

Orthotopic liver transplantations (OLT) have been associated with significant blood loss and hemodilution, necessitating significant homologous blood component replacement. Increasing administration of homologous blood products has been found to be inversely related to patient and graft survival. Various methods to reduce the amount of blood products patients receive during OLT, such as antifibrinolytic therapy, thromboelastography-guided transfusion, phlebotomy, reduced central venous pressures intraoperatively, and the use of the veno-venous bypass (VVB) circuit, have been explored. The asanguineous priming volume of the VVB circuit increases the likelihood of the patient receiving homologous blood products due to hemodilution. It was reasoned that autologous priming of the VVB circuit in OLT surgery was a plausible adjunctive blood conservation technique given its application to the extracorporeal circuit during cardiac surgery. We describe our technique of modifying the VVB circuit for autologous priming. This technique adds minimal risk and a small amount of cost to the procedure, requires slightly more communication among members of the surgical team, and with proper sequencing, adds no additional length to the surgical procedure. It is recommended that this technique be considered for addition to the arsenal of blood conservation techniques when VVB is used during OLT.

Retrograde autologous priming reduces transfusion requirements in coronary artery bypass surgery

The hypothesis was tested whether retrograde autologous priming (RAP) of the cardiopulmonary bypass system, compared to a standard primed system (NON-RAP group), results in less haemodilution and less transfusion of packed red blood cells. Retrospectively, data was collected from the medical charts of one hundred patients undergoing elective coronary artery bypass grafting using cardiopulmonary bypass. Fifty patients where RAP was used have been compared to fifty patients using NON-RAP. The prime volume in the NON-RAP group was 1,627±108 mL versus 782±96 mL in the RAP group (p<0.001). The lowest haematocrit during perfusion was 22% in the NON-RAP group versus 26% when the RAP technique was used (p<0.001). In the NON-RAP group, 26% of the patients received packed red cells in contrast to 6% in the RAP group (p<0.012). A positive association was found between RAP and less transfusion of packed red blood cells (p<0.012). In conclusion, retrograde autologous priming, reducing the prime volume of the cardiopulmonary bypass system, causes less haemodilution and reduces intraoperative transfusion of packed red blood cells.

Minimizing intraoperative hemodilution by use of a very low priming volume cardiopulmonary bypass in neonates with transposition of the great arteries

Owing to the mismatch between cardiopulomary bypass priming volume and infants' blood volume, pediatric cardiac surgery is often associated with transfusion of homologous blood, which may increase the risk of perioperative complications. Here we report the impact of a very low volume (95-110 mL) cardiopulmonary bypass circuit during arterial switch operations in neonates with transposition of the great arteries on blood requirements, tissue oxygenation, and patient outcome. Twenty-three consecutively treated neonates aged 2 to 17 days were treated with the blood-sparing approach. Asanguineous priming was used in all cases and packed red blood cells were added when hemoglobin concentration decreased below 7 g/dL. Cerebral and lower body tissue oxygenation was monitored by near-infrared spectroscopy. Intraoperative and postoperative transfusion, duration of ventilation and intensive care unit stay, wound infection, and 30-day mortality were assessed for patient outcome. Intraoperative blood transfusion was necessary in 6 of 23 neonates. An additional 11 neonates received postoperative blood transfusions on the intensive care unit, leaving 6 infants who received no blood at all. Preoperative hemoglobin concentration was the only predictor for intraoperative transfusion requirement (11.6 ± 0.9 and 13.3 ± 0.4 g/dL in infants with and without intraoperative transfusion, respectively). Despite marked differences in hemoglobin concentrations between infants with and without transfusion, regional tissue oxygenation increased in both groups during cardiopulmonary bypass and returned to baseline at the end of surgery. In-hospital patient outcome was similar in both groups. Transfusion-free complex cardiac surgery can be achieved even in neonates without jeopardizing tissue oxygenation or patient safety.

Hemodynamic evaluation of arterial and venous cannulae performance in a simulated neonatal extracorporeal life support circuit

To construct an ideal extracorporeal life support (ECLS) circuit in terms of hemodynamic performance, each component of the circuit should be evaluated. Most cannulae manufacturers evaluate their products using water as the priming solution. We conducted this study to evaluate the different sizes of arterial and venous cannulae in a simulated neonatal ECLS circuit primed with human blood. The simulated neonatal ECLS circuit was composed of a Capiox Baby RX05 oxygenator, a Rotaflow centrifugal pump and a heater & cooler unit. Three Medtronic Bio-Medicus arterial cannulae (8Fr, 10Fr, 12Fr) and three venous cannulae (10Fr, 12Fr, 14Fr) were tested in seven combinations (8A-10V, 8A-12V, 10A-10V, 10A-12V, 10A-14V, 12A-12V, 12A-14V). All the experiments were conducted using human blood at a hematocrit of 40% and at a constant temperature of 37°C. The "tip to tip" priming volume of the entire circuit was 135ml. The blood volume of the pseudo patient was 500ml. Flow rates increased linearly with increasing size in both venous and arterial cannulae at the same pump speeds. The increase in flow rate was greater when changing the arterial cannulae (next size larger) compared to changing the venous cannulae (next size larger). The pressure drops of the arterial cannula were correlated with the flow rates, regardless of the pseudo patient pressure and the venous cannula used simultaneously. The results show the difference in flow ranges and pressure drops of seven combinations of arterial and venous cannulae. It also suggests that the arterial cannula, not the venous cannula, has greater impact on the flow rate when a centrifugal pump is used in a neonatal ECLS circuit. The results of this study have been translated to further advancing the clinical practice in our institution.

In Vivo Evaluation of the “TinyPump” as a Pediatric Left Ventricular Assist Device

Pediatric patients with end-stage heart failure require mechanical circulatory support (MCS) just as adults do. In order to meet the special requirements for neonates' and infants' MCS, pediatric circulatory support devices must be compact with low priming volume, easily controllable with low flow, less traumatic for blood cells and tissues, and biocompatible with minimum anticoagulation. We have designed and developed a miniature rotary centrifugal blood pump, "TinyPump," with a priming volume of 5 mL, which has already demonstrated its controllable performance for low flow and durability in vitro. To evaluate the feasibility of the TinyPump as a left ventricular assist device (LVAD) suitable for neonates and infants, we have examined the biocompatibility and hemodynamic performance of the TinyPump in a pediatric animal model using Shiba goats. The TinyPump is a miniaturized centrifugal pump weighing 150 g comprising a disposable pump head with a 30-mm diameter impeller having six straight-vanes and a reusable motor driver. The impeller in the pump head is supported by a hydrodynamic bearing at its center and is driven by radial magnetic force coupled to the motor driver. TinyPump implantations were performed in 22 Shiba goats (17 female and 5 male), with body weights ranging from 8.4 to 27.2 kg. Under gas anesthesia, via left lateral thoracotomy, a 22 Fr inflow cannula was inserted through the left ventricular apex, while a 6-mm outflow graft was anastomosed to the descending aorta, which were then connected to a TinyPump mounted on the animal's back. Postoperative hemodynamic monitoring included heart rate, arterial and central venous pressure, pump flow, and rotation speed. Target pump flow in all animals was maintained at 0.9 ± 0.1 L/min, which is approximately half the normal pulmonary artery flow measured in control animals. Blood samples were collected to evaluate peripheral organ functions, hemolysis, and thrombosis. Goats were divided into three groups-acute phase (6 h; n = 4), subchronic phase (6 h 2 postoperative days [POD]; n = 11), and chronic phase (3 POD-16 POD; n = 8)-based on their survival duration. In the early experiments, hemolysis and thrombi formation at the impeller bearing resulted in termination of the study. Subsequent modifications of the bearing design, pump housing design, and magnetic coupling force helped to minimize the hemolysis and thrombi formation, prolonging the survival duration of the Shiba goats to 2 weeks with minimum adverse effects on the blood components and organ functions. With further experiments and improvements in pump durability and hemocompatibility, the TinyPump can serve as a suitable circulatory support device for neonates and infants bridging to heart transplantation as well as to heart recovery.

A Miniaturized Extracorporeal Membrane Oxygenator with Integrated Rotary Blood Pump: Preclinical In Vivo Testing

Extracorporeal membrane oxygenation can achieve sufficient gas exchange in severe acute respiratory distress syndrome. A highly integrated extracorporeal membrane oxygenator (HEXMO) was developed to reduce filling volume and simplify management. Six female pigs were connected to venovenous HEXMO with a total priming volume of 125 ml for 4 hours during hypoxemia induced by a hypoxic inspired gas mixture. Animals were anticoagulated with intravenous heparin. Gas exchange, hemodynamics, hemolysis, and coagulation activation were examined. One device failed at the magnetic motor coupling of the integrated diagonal pump. In the remaining five experiments, the oxygenation increased significantly (arterial oxygen saturation [SaO2] from 79 ± 5% before HEXMO to 92% ± 11% after 4 hours) facilitated by a mean oxygen transfer of 66 ± 29 ml/dl through the oxygenator. The CO2 elimination by the HEXMO reduced arterial PaCO2 only marginal. Extracorporeal blood flow was maintained at 32% ± 6% of cardiac output. Hemodynamic instability or hemolysis was not observed. The plasmatic coagulation was only mildly activated without significant platelet consumption. The HEXMO prototype provided sufficient gas exchange to prevent hypoxemia. This proof of concept study supports further development and design modifications to increase performance and to reduce coagulation activation for potential long-term application.

Surgical Closure of an Atrial Septal Defect Using Cardiopulmonary Bypass in a Cat

To describe surgical repair of a large atrial septal defect (ASD) in a cat. Clinical report. A 3-year-old, 3.3 kg, intact male Japanese domestic short-haired cat. A 10.2-mm-diameter ASD detected by echocardiography was surgically corrected because pulmonary vascular resistance-to-systemic vascular resistance ratio (Qp /Qs ) was 3.2. Using cardiopulmonary bypass (CPB), open surgical repair was achieved with an expanded polytetrafluoroethylene (e-PTFE) graft. The priming volume of the CPB circuit was minimized by cutting the CPB tubing, and partially replacing the priming fluid with whole cat blood. To prevent hemodilution associated with use of cardioprotective agents, surgery was performed on the beating heart. At 1-year echocardiographic evaluation, the repair was intact, and at 3 years, the cat was alive without need of medication. Large ASD in a cat can be repaired using e-PTFE under CPB.

298 Novel Cardiopulmonary Bypass with Reduced Priming Volume for Pig-to-Baboon Heart Transplantation Studies

In the pig-to-baboon cardiac xenotransplantation model the possibilities for transfusion of blood products are limited. Besides low intraoperative blood loss and short cardiopulmonary bypass time, a low priming volume is essential for a good postoperative condition of the recipients. We designed a novel setup of the cardiopulmonary bypass (CPB) with a low priming volume to meet the special needs of non-human primate xenotransplantation.

The comparative study of membrane oxygenator DDMO-100S and membrane oxygenator terumo SX-10 used in cardiopulmonary bypass in children

Objective To compare the gas and heat exchange performance of membrane oxygenator DDMO-100S and membrane oxygenator Terumo SX-10 in cardiopulmonary bypass(CPB)in children.Methods 39 children aged 3-12 yrs who suffered from congenital heart disease were selected,and the repair of ventricle septal defect or/and atrial septal defect was performed under cardiopulmonary bypass.The 39 children were randomly divided into Group DD(n =21)and Group SX(n = 18).Membrane oxygenator DDMO-100S(Made by Xi'an Daidai,China)was used in Group DD and Membrane oxygenator Terumo SX-10(Made by Terumo,Japan)in Group SX,respectively.The hypothermic cardiopulmonary bypass with high perfusion flow and the cool crystalloid cardioplegia were applied in all children.The artery blood samples were taken for measuring PO2 and PCO2 and the oxygenating index(OI)was calculated by the formulae(OI = PaO2/FiO2).The temperature at nasal pharynx was monitored and the rewarming time was recorded.Results The total priming volume in Group DD was bigger than in Group SX [(742.5 ± 107.3)ml vs(531.3 ± 84.3)ml,P ＜ 0.05].The PO2,OI and PCO2 at 15 min after CPB or at 5 min before cease of CPB had no differences in both group(P ＞0.05).The rewarming time had no difference in both group [(31.5 ± 10.2)min vs(30.61 ± 8.2)min,P ＞0.05].Conclusions Under our observation condition,the gas and heat exchange performance of membrane oxygenator DDMO-100S were the same as membrane oxygenator Terumo SX-10,when it was used in cardiopulmonary bypass in children,but it had a little bit more priming volume. Key words: Extracorporeal membrane oxygenation/MT; Extracorporeal circulation; Rewarming

Rat model of cardiopulmonary bypass for deep hypothermic circulatory arrest

Large animal cardiopulmonary bypass (CPB) models have disadvantages, such as cost, lack of methods for assessment of neurocognitive function, and difficulties with long-term recovery. As a result, rodent models have been developed. Previous rodent models have certain drawbacks, including irrelevance to human flows used clinically. We established a clinically relevant model of CPB with deep hypothermic circulatory arrest (DHCA) in the rat. Our CPB circuit has several novel features, including a small priming volume, active cooling/rewarming processes, vacuum-assisted venous drainage, peripheral cannulation without thoracotomy or sternotomy, and an accurate means of monitoring peripheral tissue oxygenation. This small animal model provides a simple experimental system that could be used in future studies that use CPB and DHCA.

Mini-cardiopulmonary bypass impact on blood conservation strategy in coronary artery bypass grafting

Cardiopulmonary bypass (CPB) using a closed circuit system with minimal priming volume can be a solution to ameliorate adverse effects of CPB. We hypothesize that the use of mini-bypass in routine coronary artery bypass grafting (CABG) reduces homologous blood product use and postoperative bleeding. The study is designed to determine the differences in blood loss and transfusion requirements associated with a minimized CPB circuit vs. a standard bypass circuit. From February 2009 to August 2009, 80 patients were prospectively randomized to undergo elective CABG. Group A included 40 patients who had the minimized bypass circuit (Medtronic Resting Heart Circuit). Group B had an equal number of patients who had the standard CPB circuit (Stockert III, SEC.BM). Laboratory parameters for hemoglobin, hematocrit and platelet count were measured at baseline after initiation of CPB and after bypass. Blood usage was controlled by study-specific protocol (transfusion for hemoglobin <8 g/dl). Records were kept for blood products. The chest and mediastinal drainage was monitored for the first 24 postoperative hours. Ventilation time, inotropic use and intensive care unit (ICU) stay was compared in both groups. There were no statistical differences in terms of patients' demographics. Statistically significant differences were seen in transfused red blood cells volume (1.47±1.13 units in group A vs. 2.05±1.19 in group B, P<0.05), fresh frozen plasma (2.5±1.62 unit vs. 3.55±2.58 units, P<0.001), platelets (1.95±2.95 units vs. 3.23±2.85), and postoperative drainage in 24 hours (531.62±220.12 ml vs. 729±294.9 ml, P<0.05). The hematocrit was 33±5% in group A, and 27±1% in group B. There was statistical differences seen in the mean hemoglobin level which was 10.19±0.65 g/dl in group A, and 9.4±0.68 g/dl in group B. There was statistical difference in the duration of ventilation, length of ICU stay. The requirement of inotropic support was lower in group A. The adoption of mini-bypass significantly reduces morbidity including donor blood usage and postoperative bleeding in routine CABG patients.