A good resuscitation model of non,transthoracic cardiopulmonary bypass in rats

Objective： To establish a good recoverable rat model of cardiopulmonary bypass （CPB） to lay the foundation for studying the pathophysiology of CPB. Methods： Twenty adult male Sprague-Dawley rats weighing 480 g ±20 g were randomly divided into CPB group （n = 10 ） and Sham group （ n = 10 ）. All rats were anaesthetized, intubated and ventilated. The carotid artery and jugular vein were cannulated. The blood was drained from the right atrium via the right jugular vein and further transferred by a miniaturized roller pump to a hollow fiber oxgenator and back to the rat via the left carotid artery. Priming consisted of 8 ml of homologous blood and 6 ml of colloid. The surface of the hollow fiber oxgenator was 0.075 m^2. Rats were catheterized and brought in bypass for 120 rain at a flow rate of 100-120 ml/kg/min. Oxygen flow/ perfnsion flow was 0.8 to 1.0, the mean arterial pressure （MAP） kept in 60-80 mmHg. Blood gas analysis, lactate dehydrogenase （LDH）, and survival rate were examined subsequently. Results： AH CPB rats recovered from the operative process without incident and remained uneventful within one week. Normal cardiac function after successful weaning was confirmed by electrocardiography and blood pressure measurements. MAP remained stable. The results of blood gas analysis at different time points were within a normal range. No significant haemolysis could be detected in the given time frame under bypass condition by using LDH. Conclusions： The rat model of CPB can principally simulate the clinical setting of human CPB. The nontrausthoracic model is easy to establish and is associated with excellent recovery. This well reproducible model may open the field for various studies on pathophysiological process of CPB and also of systemic ischemia-reperfusion injury in vivo.     

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.     

Preclinical evaluation of a new hollow fiber silicone membrane oxygenator for pediatric cardiopulmonary bypass: ex-vivo study.

Based on the results of many experimental models, a hollow fiber silicone membrane oxygenator applicable for long-term extracorporeal membrane oxygenation (ECMO) was developed. For further high performance and antithrombogenicity, this preclinical model was modified, and a new improved oxygenator was successfully developed. In addition to ECMO application, the superior biocompatibility of silicone must be advantageous for pediatric cardiopulmonary bypass (CPB). An ex vivo short-term durability test for pediatric CPB was performed using a healthy miniature calf for six hours. Venous blood was drained from the left jugular vein of a calf, passed through the oxygenator and infused into the left carotid artery using a Gyro C1E3 centrifugal pump. For six hours, the O2 and CO2 gas transfer rates were maintained around 90 and 80 ml/min at a blood flow rate of 2 L/min and V/Q=3, respectively. The plasma free hemoglobin was maintained around 5 mg/dl. These data suggest that this newly improved oxygenator has superior efficiency, less blood trauma, and may be suitable for not only long-term ECMO but also pediatric CPB usage.     

A rat model of cardiopulmonary bypass with excellent survival

BACKGROUND: Elucidating the underlying mechanisms and developing protective strategies for the pathophysiological consequences of cardiopulmonary bypass (CPB) have been hampered due to the absence of a satisfactory long-term recovery animal model. The objective of this study was to establish a survival experimental model of CPB in rats to meet the requirement of these studies. MATERIALS AND METHODS: Male SD rats (450-550 g) were randomly divided into CPB (n = 10) group and Sham group (n = 10). All rats were anaesthetized and mechanically ventilated. The femoral artery and vein were cannulated for continuous blood pressure recordings and fluid replacement, respectively. The CPB circuit comprised a venous reservoir, a membrane oxygenator, and a roller pump. Blood was drained from the right atrium via a jugular vein catheter and returned to the right carotid artery. Priming consisted of 8 ml of homologous blood and 8 ml of colloid. CPB was conducted for 60 min at a flow rate of 100-150 ml/kg/min in the CPB group. Haemodynamic investigations, blood gas analysis, and survival studies were performed subsequently. RESULTS: Our data show that the rat model principally simulated the clinical setting of CPB in terms of its construction, configuration, performance, material surface area, and priming volume to blood volume ratio. All CPB rats survived and the 2-week follow-up period remained uneventful. CONCLUSIONS: The rat model of CPB was easy to establish and was associated with excellent survival. This model should facilitate the investigation of the pathophysiological processes concerning CPB-related multiple organ dysfunction and possible protective interventions.     

Impact of hollow-fiber membrane surface area on oxygenator performance: Dideco D903 Avant versus a prototype with larger surface area

This study compares the gas transfer capacity, the blood trauma, and the blood path resistance of the hollow-fiber membrane oxygenator Dideco D 903 with a surface area of 1.7 m2 (oxygenator 1.7) versus a prototype built on the same principles but with a surface area of 2 m2 (oxygenator 2). Six calves (mean body weight: 68.2 +/- 3.2 kg) were connected to cardiopulmonary bypass (CPB) by jugular venous and carotid arterial cannulation, with a mean flow rate of 4 l/min for 6 h. They were randomly assigned to oxygenator 1.7 (N = 3) or 2 (N = 3). After 7 days, the animals were sacrificed. A standard battery of blood samples was taken before the bypass, throughout the bypass, and 24 h, 48 h, and 7 days after the bypass. The oxygenator 2 group showed significantly better total oxygen and carbon dioxide transfer values throughout the perfusion (p < .001 for both comparison). Hemolytic parameters (lactate dehydrogenase and free plasma hemoglobin) exhibited a slight but significant increase after 5 h of bypass in the oxygenator 1.7 group. The pressure drop through the oxygenator was low in both groups (range, 43-74 mmHg). With this type of hollow-fiber membrane oxygenator, an increased surface of gas exchange from 1.7 m2 to 2 m2 improves gas transfer, with a limited impact on blood trauma and no increase of blood path resistance.     

A clinical study on brain perfusion during cardiopulmonary bypass

The purpose of this study was to determine the optimum cerebral perfusion flow rate and pressure of the selective cerebral perfusion. Blood flows of the brachiocephalic and left common carotid artery in 34 patients were continuously monitored by means of electromagnetic flow meter during cardiac operations. Radial and common carotid arterial pressure were monitored simultaneously. Arterial and internal jugular venous blood were sampled and cerebral oxygen consumption was calculated. During steady state hypothermic cardiopulmonary bypass (CPB), mean cerebral perfusion flow was about 600 ml/min at CPB flow of 2.4 L/min/m2. Cerebral oxygen consumption was decreased to 50% of the prebypass level during steady state hypothermic CPB and then it returned to prebypass level after CPB. Common carotid arterial pressure was about 10 mmHg lower than radial arterial pressure during CPB. When CPB flow was remained at 2.4 L/min/m2, left common carotid arterial flow was not affected by common carotid arterial pressure within the range of 40 to 80 mmHg. Cerebral autoregulation might be preserved at this pressure level of the common carotid artery. When CPB flow was reduced from 2.4 L/min/m2, cerebral oxygen consumption was remained constant level until the flow reached to 1.6 L/min/m2, at which cerebral perfusion flow was about 400 ml/min. Data suggest that optimum cerebral perfusion flow during the selective cerebral perfusion may be about 600 ml/min although cerebral oxygen consumption was maintained when cerebral perfusion flow was reduced to 400 ml/min. Optimum cerebral perfusion pressure was 40-80 mmHg of carotid arterial pressure and when monitored in radial artery, more than 10 mmHg higher pressure should be required.     

Partial cardiopulmonary bypass in rats using a hollow fibre oxygenator

Despite new minimally invasive techniques, cardiopulmonary bypass (CPB) is still necessary for many major operations in the field of cardiac surgery. Unwanted side effects of CPB are well known but poorly understood. We therefore developed a rodent model to study the pathophysiology of these potential complications. Male Fischer rats were anaesthetized, intubated and ventilated. The carotid artery and jugular vein were cannulated. The blood was actively drained from the venous circulation and further transferred by a miniaturized roller pump to a hollow fibre oxygenator and back to the animal via the carotid artery. The roller pump produces a pulsatile blood flow between 5 and 40 ml/min. The surface of the hollow fibre oxygenator is 0.025 m2. The priming volume (Ringer solution) of the whole system is 12 ml. Animals were catheterized and brought in partial bypass for a mean of 50+/-15 min. Normal cardiac function after successful weaning was confirmed by electrocardiography and blood pressure measurements. This technical study demonstrates the feasibility of a small animal model of CPB. The main improvement over existing techniques is the use of a highly effective hollow fibre oxygenator with a minimized priming volume. Therefore, no additional animals are needed as blood donors.     

A clinical study of cerebral perfusion during pulsatile and nonpulsatile cardiopulmonary bypass

The purpose of this study was to determine the effect of pulsatile flow on cerebral perfusion under cardiopulmonary bypass (CPB). Twenty-three patients who underwent cardiac operations were divided into two comparable groups: Group A (N = 11) had standard nonpulsatile flow, while in Group B (N = 12), a pulsatile pump was used. The blood flow of left common carotid artery and radial arterial pressure were continuously monitored during cardiac operation in both groups and cerebral vascular resistance was calculated. In Group B, the perfusion pressure of left common carotid artery was monitored and compared with that of radial artery. Arterial and internal jugular venous blood were sampled and the difference of cerebral A.V O2 contents and cerebral oxygen consumption was calculated. Cerebral vascular resistance in Group B (54.0 +/- 11.2% of the value of before-CPB) significantly decreased compared to that in Group A (72.2 +/- 11%) at the end of CPB (p less than 0.05). Pulse pressure following pulsatile CPB flow was 15.1 +/- 5.8 mmHg monitored in radial artery and it reduced to 8.5 +/- 5 mmHg in left common carotid artery. Although there was no significant difference in cerebral oxygen consumption of both groups during and just after CPB, the difference of cerebral A-V O2 contents of Group B was greater than Group A just after CPB. These data suggest that pulsatile flow may minimize the cerebral microcirculatory shunt during CPB, resulting from the reduction of cerebral vascular resistance.     

Temperature Control Using a Heat Exchanger of a Cardioplegic System in Cardiopulmonary Bypass Model for Rats

Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. However, the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by heat exchanger (HE) is among them. The purpose of this study was to confirm the effect of rectal temperature maintenance and hypothermic control using a HE of cardioplegia system in CPB model for rats. The miniature circuit consisted of a reservoir, HE, membrane oxygenator, and roller pump; the static priming volume was 40 cc. In the first stage of experiment, 10 male Sprague‐Dawley rats were divided into two groups; HE group was subjected to CPB with HE from a cardioplegia system, and control group was subjected to CPB with warm water circulating around the reservoir. Partial CPB was conducted at a flow rate of 40 mg/kg/min for 20 min after venous cannulation (via the internal jugular vein) and arterial cannulation (via the femoral artery). Rectal temperature was measured after anesthetic induction, after cannulation, 5, 10, 15, and 20 min after CPB. Arterial blood gas with hematocrit was also analyzed, 5 and 15 min after CPB. In the second stage with the same experimental setting, rectal temperatures were lowered in 10 rats to the target temperature of 32°C. After reaching the target temperature, animals were rewarmed. Rectal temperature was measured after cannulation, 5, 10, 15, 20, 25, and 30 min after CPB. Arterial blood gas with hematocrit was also analyzed, 5 and 15 min after CPB. Rectal temperature change differed between the two groups (P < 0.01). The temperatures of the HE group were well maintained during CPB, whereas the control group was under progressive hypothermia. Rectal temperature 20 min after CPB was 36.16 ± 0.32°C in the HE group and 34.22 ± 0.36°C in the control group. In the second set of experiments, the hypothermia targeted (32°C) was reached in 15 min (from 35.56 ± 1.05°C to 31.75 ± 0.47°C). The rats were successfully rewarmed within the observation period of 30 min. Arterial blood gases and hematocrits showed no further significant findings. We confirmed the effect of rectal temperature maintenance and hypothermic control using an HE of cardioplegia system in CPB model for rats. This model would be a valuable tool for further use in hypothermic CPB experiments in rats.     

单唾液酸神经节苷脂对大鼠体外循环脑损伤及细胞外信号调节激酶信号通路的影响

目的探讨单唾液酸神经节苷脂（monosialotetmhexosylganglioside,GM-1）对大鼠体外循环（cardiopulmonary bypass,CPB）脑损伤及细胞外信号调节激酶（extrallular signal regulated proteinkinase,ERK1／2）信号通路的影响。方法成年雄性sD大鼠27只,体重350g-450g,采用随机数字表法将其随机分成3组（每组9只）：空白对照组（阴性对照组,S组）、CPB对照组（阳性对照组,B组）、GM-1干预组（实验组,C组）。采用右颈静脉腔房引流、右颈动脉灌注建立大鼠体外循环模型。S组不建模型,穿刺后进行机械通气60min,B组和c组进行CPB 60min,其中C组转流液中加入GM-1（20mg／kg）,B组给予相同体积的生理盐水。于转流前（T0）、CPB转流即刻（T1）、CPB15 min（T2）、CPB45 min（T,）、CPB结束后1h（T4）时记录平均动脉压（mean artery pressure,MAP）及血气分析指标。CPB结束和S组机械通气后3h时断头取脑组织标本,透射电镜观察皮质超微结构变化;原位细胞凋亡检测法[terminal dexynucteotidyl transferase（TdT）-mediated dUTP nick end labeling,TUNEL]标记皮质神经元凋亡数;免疫组化和免疫印迹（Western-blot）法检测ERK1／2蛋白的表达。结果B组和C组转流中平均动脉压、心率、血气、红细胞比容比较,差异无统计学意义;与S组比较,B组和C组皮质神经元损伤严重,凋亡的神经细胞数目分别增加220％和147％,ERK1／2蛋白活性分别升高65％和41％（P〈0．05）;与B组比较,C组皮质神经元损伤明显减轻,凋亡的神经细胞数目减少24％,ERK1／2蛋白活性降低15％（P〈0．05）。结论GM-1对体外循环脑损伤有保护作用,其机制可能与抑制ERK1／2信号通路减少神经细胞凋亡有关。     

双歧三联活菌预处理对体外循环后大鼠肠黏膜屏障功能的影响

目的 探讨双歧三联活菌预处理对体外循环(CPB)后大鼠小肠黏膜屏障功能的影响.方法 成年雄性SD大鼠24只,体重350～450 g,随机分为3组(n=8):假手术组(S组)、CPB组和双歧三联活菌预处理组(P组).CPB开始前7 d,P组每天用双歧三联活菌2 ml(含活菌数1×10~7 CFO)灌胃,S组和CPB组用生理盐水2 ml灌胃.第8天进行CPB 60 min.CPB结束后2 h时处死大鼠,抽取门静脉血,采用分光光度法测定血浆二胺氧化酶活性和D-乳酸浓度,鲎试验偶氮显色法测定内毒素浓度,放免法测定血浆TNF-α和IL-6的浓度.取腔静脉血,肝、肺、肾组织及肠系膜淋巴结,分别接种于血平皿上培养,24 h后鉴定细菌生长情况及细菌种类,光镜下观察小肠上皮组织病理学.结果 与S组相比,CPB组和P组血浆D-乳酸、内毒素、TNF-α和IL-6的浓度、二胺氧化酶活性及细菌易位率升高(P<0.05);与CPB组相比,P组上述各指标降低(P<0.05).病理结果显示P组小肠上皮组织损伤程度较CPB组明显减轻.结论 双歧三联活菌预处理可在一定程度上抑制炎性反应,保护CPB后大鼠小肠黏膜屏障功能.     

大鼠体外循环心肌胰岛素抵抗实验模型的建立

目的构建大鼠体外循环(CPB)心肌缺血再灌注损伤(MIRI)实验模型并评估其诱导心肌胰岛素抵抗(IR)的效果。方法12只雄性SD大鼠采用随机数字表法分为两组,对照组不阻断主动脉(n=6),模型组主动脉阻断30 min再灌注15 min(n=6);经尾动脉置入灌注管、右侧颈外静脉插入右心房引流管、开胸阻断升主动脉,建立体外循环(CPB),于开放主动脉后15 min采集血液及心肌组织标本,检测血浆葡萄糖、胰岛素水平并进一步计算葡萄糖摄取率、胰岛素抵抗指数(IRI)的变化。采用蛋白质印迹法(Western blot)、免疫荧光检测心肌细胞膜葡萄糖转运蛋白4(GLUT4)的表达。组间比较采用独立样本t检验。结果缺血再灌注后15 min,模型组[静脉葡萄糖浓度(Glu-V)(20.23±0.30)mmol/L;胰岛素浓度(15.89±1.72)mIU/L;IRI(14.29±1.59)]高于对照组[Glu-V(8.31±0.67)mmol/L;胰岛素浓度(6.54±1.77)mIU/L;IRI(2.42±0.73),t=38.945、9.286、16.593,P值均<0.01],差异有统计学意义。而模型组葡萄糖摄取率为(7.68±2.29)%低于对照组[(45.46±3.67)%,t=21.410,P<0.01],差异有统计学意义。模型组左心室收缩压(LVSP)为(34.8±6.6)mmHg低于对照组LVSP[(60.4±6.9)mmHg,t=-6.586,P<0.01],差异有统计学意义。模型组Western blot所测心肌细胞膜蛋白相对表达量为(0.30±0.08)低于对照组(1.04±0.21,t=7.979,P<0.01),差异有统计学意义。结论成功建立操作简便、经济适用、个体差异小且更能模拟临床的CPB缺血再灌注心肌IR大鼠模型。     

Neurologic recovery after deep hypothermic circulatory arrest in rats: A description of a long‐term survival model without blood priming

Brain injury associated with deep hypothermic circulatory arrest (DHCA) has been recognized in patients with congenital heart diseases and those undergoing aortic arch surgeries. However, the preclinical investigation of long‐term cerebral injury and recovery mechanisms related to DHCA has been restricted to a satisfactory recovery animal model with a determined recovery time. This study aimed to evaluate the feasibility of a long‐term surviving DHCA model without blood priming in rats, in order to investigate the pathophysiology of long‐term complications in further studies. Twelve Sprague‐Dawley rats were divided into 2 groups: sham group (n = 3) and DHCA group (n = 9). The DHCA group was further assigned to the surviving time of postoperative day 2, 14, and 30 (n = 3, respectively). The entire cardiopulmonary bypass (CPB) circuit consisted of a modified reservoir, a custom‐designed small‐volume membrane oxygenator, a roller pump and a heater/cooler. A 24‐G catheter was cannulated in the branch of the left femoral artery for arterial blood pressure monitoring. Cardiopulmonary bypass was established via the right external jugular vein–right atrium and tail artery. Rats were cooled to a rectal temperature of 18°C, followed by 30 minutes of DHCA with global ischemia. After re‐warming for approximately 40 minutes, the animals were weaned from the CPB at 35.5°C. Blood gas and hemodynamic parameters were recorded preoperatively and intraoperatively, and at 2, 14, and 30 days postoperatively. Thereafter, the brains were perfusion fixed and histologically analyzed. All DHCA processes were successfully achieved, and none of the rats died. Blood gas analysis and hemodynamic parameters at each time point were normal, and vital signs of all rats were stable. Histopathologic deficits in the hippocampus (pathological score, surviving hippocampal neurons, and Ki67‐positive neurons) manifested after 30 minutes of DHCA, which persisted for at least 14 days and recovered after 30 days. A novel and simple long‐term recovery model of DHCA in rats was established in the present study, and histopathologic deficits were observed after clinically relevant 30‐minute DHCA durations, in order to determine the 30‐day recovery time frame.     

Transapical aortic cannulation via left lateral thoracotomy for descending thoracic and thoracoabdominal aortic surgery

Two patients underwent surgery for a chronic type B dissection using a total cardiopulmonary bypass (CPB) with transapical arterial cannulation. At surgery, a total CPB was established by cannulating the left femoral artery and the ascending aorta via the ventricular apex. The patients were cooled to 30°C. The proximal anastomosis was done after cross-clamping the aortic arch between the left carotid artery and the left subclavian artery in both cases. In the first case, the entire descending thoracic aorta was replaced, and two pairs of intercostal arteries were reconstructed. The other patient underwent replacement of the proximal descending thoracic aorta. Neither patient experienced any complications. Transapical aortic cannulation is a useful option during descending thoracic and thoracoabdominal aortic surgery. It can provide more stable circulation during the cross-clamping, more gentle manipulation of the aorta by nonpulsatile flow, and more liberty in temperature control.     

Lung perfusion during cardiac surgery with cardiopulmonary bypass: is it necessary?

Thirty-two pigs were randomized into group I (aortic cross clamping, antegrade cardioplegia, moderate hypothermia) and group II (normothermia, beating empty heart). Groups were subdivided into subgroups A, B and C, receiving no lung perfusion, perfusion with arterial blood and perfusion with venous blood. Swan-Ganz catheter was used to take mean pulmonary artery pressure which would be used as lung perfusion pressure. Cardiopulmonary bypass (CPB) was established through cannulating aorta and double venae cavae, mechanical ventilation was interrupted and lung perfusion was carried out for 30 min. Blood samples and pulmonary specimens were withdrawn pre- and postoperatively for gasometrical, histological and genic analyses. Postoperative comparison revealed that pulmonary vascular resistance was lower in IC than IA (P=0.01) and it was lower in IIC than IIA (P=0.005). Subgroup IIB had increasing venous oxygen tension (P=0.01) as well as arterial and venous oxygen saturation (P=0.01) compared to IIA. Arterial oxygen saturation was decreased in IIC vs. IIA (P=0.006). Histological differences were observed between subgroups A and B as well as A and C (P=0.003). Lung perfusion during CPB may improve pulmonary hemodynamic performance, optimize gas exchange and maintain cellular integrity.     

Establishment of a novel miniature veno‐venous extracorporeal membrane oxygenation model in the rat

Recently, veno‐venous extracorporeal membrane oxygenation (V‐V ECMO) has been commonly used in the world to support patients with severe respiratory failure. However, V‐V ECMO is a new technology compared to veno‐arterial extracorporeal membrane oxygenation and cardiopulmonary bypass, and there are few reports of basic research. Although continuing research is desired, clinical research that standardizes conditions such as patients’ background characteristics is difficult. The purpose of this study was to establish a simple and stably maintainable miniature V‐V ECMO model to study the mechanisms of the biological reactions in circulation during V‐V ECMO. The V‐V ECMO system consisted of an original miniature membrane oxygenator, polyvinyl chloride tubing line, and roller pump. The priming volume of this system was only 8 mL. Polyethylene tubing was used to cannulate the right femoral vein as the venous return cannula for the V‐V ECMO system. A 16‐G cannula was passed through the right internal jugular vein and advanced into the right atrium as the conduit for venous uptake. The animals were divided into 2 groups: SHAM group and V‐V ECMO group. V‐V ECMO was initiated and maintained at 50‐60 mL/kg/min, and oxygen was added into the oxygenator during V‐V ECMO at a concentration of 100% (pump flow:oxygen = 1:10). Blood pressure was measured continuously, and blood cells were measured by blood collection. During V‐V ECMO, the blood pressure and hemodilution rate were maintained around 80 mm Hg and 20%, respectively. Hb was kept at >10 g/dL, and V‐V ECMO could be maintained without blood transfusion. It was possible to confirm oxygenation of and carbon dioxide removal from the blood. Likewise, the pH was adequately maintained. There were no problems with this miniature V‐V ECMO system, and extracorporeal circulation progressed safely. In this study, a novel miniature V‐V ECMO model was established in the rat. A miniature V‐V ECMO model appears to be very useful for studying the mechanisms of the biological reactions during V‐V ECMO and to perform basic studies of circulation assist devices.     

Analysis of factors related to jugular venous oxygen saturation during cardiopulmonary bypass

OBJECTIVE: To investigate preoperative clinical conditions and/or intraoperative physiologic variables related to jugular venous oxygen saturation (SjO2) during cardiopulmonary bypass (CPB). DESIGN: Prospective study. SETTING: General hospital, single institution. PARTICIPANTS: One hundred forty patients (52 women, 88 men) who underwent coronary artery bypass grafting. MEASUREMENTS AND MAIN RESULTS: The authors measured SjO2 at five times during surgery. Multiple stepwise regression analysis showed a significant correlation of SjO2 with (1) arterial carbon dioxide partial pressure (PaCO2) before CPB (standard regression coefficient [(SC)] = 0.435), (2) cerebral perfusion pressure (CPP) during initiation of CPB (SC = 0.259), (3) PaCO2, tympanic temperature (TT), bubble oxygenator, and cerebral small infarctions (CSIs) during hypothermic CPB (SC = 0.507, -0.237, -0.192, and -0.189, respectively), (4) CPP, PaCO2, CSIs, and bubble oxygenator during rewarming (SC = 0.476, 0.294, -0.220, and -0.189, respectively), and (5) PaCO2 after CPB (SC = 0.480; p < 0.01). Correlation coefficients between SjO2 and CPP during rewarming were 0.40 (0.46 without CSI and 0.37 with CSI; p < 0.01). These results indicate that the relationship between CPP and SjO2 was significant in patients with CPP less than 40 mmHg during rewarming. CONCLUSION: During rewarming, when cerebral perfusion and oxygen demand change abruptly, but not during stable hypothermic CPB, CPP was a significant factor related to sjO2.     

A prospective,double-blind study on the efficacy of the bioline surface-heparinized extracorporeal perfusion circuit

BACKGROUND: We evaluated the newly introduced Bioline heparin coating and tested the hypothesis that surface heparinization limited to the oxygenator and the arterial filter will ameliorate systemic inflammation and preserve platelets during cardiopulmonary bypass (CPB). METHODS: In a prospective double-blind study, 159 patients underwent coronary revascularization using closed-system CPB with systemic heparinization, mild hypothermia (33 degrees C), a hollow-fiber oxygenator, and an arterial filter. The patients were randomly divided in three groups. In group A (controls, n = 51), surface heparinization was not used. In group B (n = 52), the extracorporeal circuits were totally surface-heparinized with Bioline coating. In group C (n = 56), surface heparinization was limited to oxygenator and arterial filter. RESULTS: No significant difference was noted in patient characteristics and operative data between groups. Operative (30-day) mortality was zero. Platelet counts dropped by 12.3% of pre-CPB value among controls at 15 minutes of CPB, but were preserved in groups B and C throughout perfusion (p = 0.0127). Platelet factor 4, plasmin-antiplasmin levels, and tumor necrosis factor-alpha increased more in controls during CPB than in groups B or C (p = 0.0443, p = 0.0238 and p = 0.0154 respectively). Beta-thromboglobulin, fibrinopeptide-A, prothrombin fragments 1 + 2, factor XIIa levels, bleeding times, blood loss, and transfusion requirements were similar between groups. Intensive care unit stay was shorter in groups B and C than in controls (p = 0.037). CONCLUSIONS: Surface heparinization with Bioline coating preserves platelets, ameliorates the inflammatory response and is associated with a reduced fibrinolytic activity during CPB. Surface heparinization limited to the oxygenator and the arterial filter had similar results as totally surface-heparinized circuits.     

Cardiopulmonary bypass does not alter canine enflurane requirements.

This study determined the effect of cardiopulmonary bypass (CPB) on canine enflurane minimum alveolar concentration (MAC). Fourteen dogs were anesthetized with enflurane in N2O and O2, and after tracheal intubation, the N2O was discontinued. Femoral arterial and pulmonary arterial catheters were placed, and MAC was determined with the tail-clamp method. CPB was initiated via the femoral artery-vein route, with additional venous return obtained from an external jugular vein. Partial CPB was used in the first 10 dogs. In 4 dogs, a membrane oxygenator (group 1) was used, and in the next 6 dogs a bubble oxygenator (group 2) was used. In 4 additional dogs (group 3), using bubble oxygenators, total CPB was achieved by occlusion of the pulmonary artery via a left thoracotomy. The CPB circuit was primed with Ringer's lactate, and circuit blood flows were 70-125 ml.kg-1.min-1, with mean arterial pressures maintained at 50-110 mmHg. MAC was determined again after termination of CPB. In 10 dogs, MAC was also measured during CPB. In 5 dogs MAC was measured after administration of protamine. MAC in all 14 dogs did not change (2.2 +/- 0.3 vs. 2.3 +/- 0.3). MAC remained constant in group 1 (2.4 +/- 0.3 vs. 2.3 +/- 0.4), group 2 (2.2 +/- 0.2 vs. 2.3 +/- 0.3), and group 3 (2.2 +/- 0.1 vs. 2.3 +/- 0.1). Similarly, MAC was unchanged during CPB (2.2 +/- 0.2 vs. 2.2 +/- 0.2) and after protamine (2.3 +/- 0.2 vs. 2.2 +/- 0.3). Temperature was 38.3 +/- 1.2 prebypass and 37.9 +/- 0.9 postbypass.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lethal thrombus in the carotid artery during operation for acute aortic dissection with cerebral malperfusion

A drowsy patient with acute type A aortic dissection and cerebral malperfusion required emergency operation. Because the right carotid artery was totally obstructed, cerebral perfusion was first restored by cannulating it and the left femoral artery before midline sternotomy. However, a long fresh thrombus was found flowing backward from the obstructed carotid artery. This thrombus was removed, and both arteries were connected through a Y-shaped extracorporeal circulation circuit to reperfuse the brain. During the subsequent aortic procedure, both arteries were used for arterial inflow. Such thrombi can cause grave postoperative neurologic dysfunction. Carotid artery cannulation is mandatory in such cases.