Injury in organs after cardiopulmonary bypass: a comparative experimental morphological study between a centrifugal and a new pulsatile pump

The aim of this investigation was to assess organ injury provoked by a new pulsatile pump for cardiopulmonary bypass (CPB) with respect to a conventional centrifugal pump. Eight pigs in the pulsatile group (PG) and five in the centrifugal group (CG) underwent a partial CPB lasting 180 min. The animals were sacrificed 180 min after CPB was suspended, and a morphological study of fragments of ventricular wall, liver, lung, and kidney was performed. In CG, centrilobular hepatic necrosis was observed accompanied by sinusoidal dilatation and congestion, multiple focuses of myocardial ischemia, and minor to moderate pulmonary interstitial edema. In PG, diffuse centrilobular sinusoidal congestion in the liver, congestion and capillary dilatation of low intensity in the ventricular wall, and nonsignificant pulmonary interstitial septal edema was observed. In the kidney, both groups showed degenerative changes of the tubular cells and nonsignificant tubular dilatation. These results suggest a better peripheral circulation in the pulsatile group.     

The effects of pulsatile and non-pulsatile cardiopulmonary bypass on renal blood flow and function

The physiologic effects of pulsatile and non-pulsatile flow in cardiopulmonary bypass were compared in terms of the relationship between different flow rates and what effects these had on pulsatile and non-pulsatile flow. Forty adult mongrel dogs were used in this study and divided into 5 groups, each comprised of 8 animals, according to the flow rate during cardiopulmonary bypass, namely; 40, 60, 80, 100, or 120 ml/kg/min. The animals were perfused with either pulsatile or non-pulsatile flow for 1 hour, given randomly at the same mean flow rate. At flow rates of 80 and 100 ml/kg/min, the mean arterial blood pressure and total peripheral vascular resistance were significantly lower in pulsatile flow than in non-pulsatile flow, and the renal blood flow was significantly greater in pulsatile flow than in non-pulsatile flow. The renal arterial-venous lactate difference was significantly less in pulsatile flow than in non-pulsatile flow at a flow rate of 80 ml/kg/min, and the renal lactate extraction was significantly higher in pulsatile flow than in non-pulsatile flow at the same flow rate. The renal excess lactate was significantly lower in pulsatile flow than in non-pulsatile flow at a flow rate of 100 ml/kg/min. There were no significant differences in these parameters between the two types of perfusion at flow rates of 40, 60 or 120 ml/kg/min. Pulsatile flow was therefore apparently advantageous, when compared to non-pulsatile flow, in terms of hemodynamics, renal circulation, and metabolism of the kidney at flow rates of 80 and 100 ml/kg/min. However, when the flow rate was 120 ml/kg/min, pulsatile flow and non-pulsatile flow had the same effects.     

Clinical effectiveness of centrifugal pump to produce pulsatile flow during cardiopulmonary bypass in patients undergoing cardiac surgery

Although the centrifugal pump has been widely used as a nonpulsatile pump for cardiopulmonary bypass (CPB), little is known about its performance as a pulsatile pump for CPB, especially on its efficacy in producing hemodynamic energy and its clinical effectiveness. We performed a study to evaluate whether the Rotaflow centrifugal pump produces effective pulsatile flow during CPB and whether the pulsatile flow in this setting is clinically effective in adult patients undergoing cardiac surgery. Thirty-two patients undergoing CPB for elective coronary artery bypass grafting were randomly allocated to a pulsatile perfusion group (n = 16) or a nonpulsatile perfusion group (n = 16). All patients were perfused with the Rotaflow centrifugal pump. In the pulsatile group, the centrifugal pump was adjusted to the pulsatile mode (60 cycles/min) during aortic cross-clamping, whereas in the nonpulsatile group, the pump was kept in its nonpulsatile mode during the same period of time. Compared with the nonpulsatile group, the pulsatile group had a higher pulse pressure (P < 0.01) and a fraction higher energy equivalent pressure (EEP, P = 0.058). The net gain of pulsatile flow, represented by the surplus hemodynamic energy (SHE), was found much higher in the CPB circuit than in patients (P < 0.01). Clinically, there was no difference between the pulsatile and nonpulsatile groups with regard to postoperative acute kidney injury, endothelial activation, or inflammatory response. Postoperative organ function and the duration of hospital stay were similar in the two patient groups. In conclusion, pulsatile CPB with the Rotaflow centrifugal pump is associated with a small gain of EEP and SHE, which does not seem to be clinically effective in adult cardiac surgical patients.     

A new method of providing pulsatile flow in a centrifugal pump: assessment of pulsatility using a mock circulatory system

Abstract:  Previous studies have demonstrated the potential advantages of pulsatile flow as compared with continuous flow. However, to date, physiologic pumps have been technically complex and their application has therefore remained in the experimental field. We have developed a new type of centrifugal pump, which can provide pulsatile as well as continuous flow. The inner wall of a centrifugal pump is pulsed by means of a flexible membrane, which can be accurately controlled by means of either a hydraulic or pneumatic driver. The aim of this study was to assess the hydraulic behavior of the new pump in terms of surplus hemodynamic energy (SHE). We conducted experiments using a mock circulatory system including a membrane oxygenator. No differences were found in the pressure–flow characteristics between the new pump and a conventional centrifugal pump, suggesting that the inclusion of the flexible membrane does not alter hydraulic performance. The value of SHE rose when systolic volume was increased. However, SHE dropped when the percentage of ejection time was reduced and also when the continuous flow (programed by the centrifugal console) increased. Mean flow matched well with the continuous flow set by the centrifugal console, that is, the pulsatile component of the flow was exclusively controlled by the pulsatile console, and was therefore independent of the continuous flow programed by the centrifugal console. The pulsatility of the new pump was ∼25% of that created with a truly pulsatile pump.     

Intra-aortic balloon pump-induced pulsatile flow reduces coagulative and fibrinolytic response to cardiopulmonary bypass

Abstract:  The aim of this study is to evaluate if a simple intra-aortic balloon pump (IABP)-induced pulsatile perfusion reduces activation of coagulative system during cardiopulmonary bypass (CPB). Ninety-six patients undergoing preoperative IABP were randomized to nonpulsatile CPB with IABP discontinued during cardioplegic arrest (Group A) or IABP-induced pulsatile CPB (Group B). White blood cells (WBC), hematocrit (Ht), platelets (PLTs), International Normalized Ratio (INR), fibrinogen, activated partial thromboplastin time (aPTT), antithrombin III (AT-III) activity, and D-dimer were measured at the end of surgery (ES) and postoperatively. Chest drainage, need for reexploration, and transfusions were compared. Group B showed lower chest drainage (1st day P  = 0.038; 2nd day P  = 0.044), transfusions ( P  = 0.031), WBC ( P  < 0.05 at all time points), and INR ( P  < 0.05 at all time points), together with a higher Ht ( P  < 0.05 at ES, 12 h), platelets ( P  < 0.04 at all time points), fibrinogen ( P  < 0.05 at ES, 12 h, 24 h), and aPTT ( P  < 0.05 at all time points). AT-III activity lowered in Group A ( P  = 0.001 at ES, 12 h, 24 h), together with higher D-dimer levels ( P  < 0.05 at all time points). IABP-induced pulsatile perfusion ameliorates coagulative system activation following CPB.     

A pulsatile pump for cardiopulmonary bypass and its clinical use

A pulsatile pump driven by a coil spring, which was designed and constructed by us, is described in this report. It consists of two main parts, a disposable blood chamber and a driving section. The blood chamber has two leaflet valves and a piston, which is covered with two bellofram rolling diaphragms and moves into the housing to draw in and eject the blood. The driving section consists of three cams, an electric motor and a coil spring. The ejection force is wholly produced by the compressed coil spring and is transmitted to the piston in the blood chamber by a rod. This pump allows the ejection pressure, the beat rates, and the stroke volume all to be changed independently. The performance of the pump was tested by using a circulation model where the beat rate was adjusted from 30 to 250 bpm. The output subsequently increased from 0.81/min to 5.71/min and the stroke volume, from 20.4 ml to 36.7 ml. This new pump has been used for clinical cardiopulmonary bypasses in 24 patients of open heart surgery and the pressure traces during perfusion resembled those of the patients’ own hearts.     

"Orpheus" cardiopulmonary bypass simulation system

In this paper we describe a high-fidelity perfusion simulation system intended for use in the training and continuing education of perfusionists. The system comprises a hydraulic simulator, an electronic interface unit and a controlling computer with associated real-time computer models. It is designed for use within an actual operating theatre, or within a specialized simulation facility. The hydraulic simulator can be positioned on an operating table and physically connected to the circuit of the institutional heart-lung machine. The institutional monitoring system is used to display the arterial and central venous pressures, the ECG and the nasopharyngeal temperature using appropriate connections. The simulator is able to reproduce the full spectrum of normal and abnormal events that may present during the course of cardiopulmonary bypass. The system incorporates a sophisticated blood gas model that accurately predicts the behavior of a modern, hollow-fiber oxygenator. Output from this model is displayed in the manner of an in-line blood gas electrode and is updated every 500 msecs. The perfusionist is able to administer a wide variety of drugs during a simulation session including: vasoconstrictors (metaraminol, epinephrine and phenylephrine), a vasodilator (sodium nitroprusside), chronotropes (epinephrine and atropine), an inotrope (epinephrine) and modifiers of coagulation (heparin and protamine). Each drug has a pharmacokinetic profile based on a three-compartment model plus an effect compartment. The simulation system has potential roles in the skill training of perfusionists, the development of crisis management protocols, the certification and accreditation of perfusionists and the evaluation of new perfusion equipment and/or techniques.     

有创血压波形监测下体外循环搏动灌注效果初步评价

目的 探索桡动脉有创血压波形作为搏动灌注质控指标的可能性,并在此监测下评价搏动灌注的有效性.方法 选取2008年3月至12月需在体外循环下手术治疗的患者80例,随机分为搏动灌注组(P组)45例和非搏动灌注组(NP组)35例.主动脉阻断期间P组在桡动脉波形监测下建立搏动灌注,NP组采用常规平流灌注.将P组形成显著双峰波或单峰波(脉压差＞30 mm Hg,1 mm Hg=0.133 kPa)的病例与NP组比较,检测手术前后肌酐、尿素氮、血尿酸、乳酸脱氢酶、谷草转氨酶、超敏C反应蛋白,术中乳酸、尿量,手术后尿隐血率、心跳自复率、凝血酶原时间等指标.结果 P组有35例形成显著的双峰波形或单峰波.与NP组比较:术中乳酸较低(P＜0.01),单位时间尿量较多(P＜0.01),术后乳酸脱氢酶上升幅度(P＜0.05)、超敏C反应蛋白(P＜0.05)和凝血酶原时间(P＜0.01)较低.P组术后血尿酸下降,而NP组上升(P＜0.01);尿隐血、手术前后谷草转氨酶差率、心跳自复率两组差异无统计学意义.结论 通过设备优化和搏动参数的调控,能建立有效的搏动灌注和能最传递;桡动脉有创血压波形监测是方便有效的搏动灌注指标;在桡动脉波形监测下的搏动灌注各项监测指标明显优于平流灌注.     

Pulsatile flow improves cerebral blood flow in pediatric cardiopulmonary bypass

The objective of this study was to evaluate the effect of pulsatile flow on cerebral blood flow (CBF) in infants with the use of a mild hypothermic cardiopulmonary bypass (CPB). Thirty infants scheduled for open heart surgery were randomized to the pulsatile group (Group P, n = 15) and nonpulsatile group (Group NP, n = 15). In Group P, pulsatile perfusion was applied during the aortic cross‐clamping period, whereas nonpulsatile perfusion was used in Group NP. The systolic peak velocity (Vs), the end of diastolic velocity (Vd), the mean velocity (Vm), and the pulsatility index (PI) and the resistance index (RI) of the middle cerebral artery were measured by a transcranial Doppler (TCD) ultrasound after anesthesia (T1; baseline), at the beginning of CPB (T2), 10 min after aortic cross‐clamping (T3), 3 min after declamping (T4), at the cessation of CPB (T5), and at the end of the operation (T6). During T3 and T4, the Vs in Group P was significantly higher than in Group NP. However, there were no statistically significant differences between Vd and Vm. The PI and RI in Group P were also higher than those in Group NP (both P < 0.05). During T5, Vd and Vm were higher in Group P (P < 0.05), whereas there was no difference in Vs. Additionally, PI and RI in Group P were significantly lower than those in Group NP (P < 0.05). However, there was no difference during T6. Pulsatile perfusion may increase CBF and decrease cerebral vascular resistance in the early period after mild hypothermic CPB.     

Analysis of pulsatile and nonpulsatile blood flow effects in different degrees of stenotic vasculature

Vessel lumens that have been chronically narrowed by atherosclerosis should be increased in flow velocity and intrastenotic area pressure to maintain an equal flow. This might be followed by a decrease in hemodynamic energy, leading to a reduction of tissue perfusion. In this study, we compared hemodynamic energies according to degrees of stenotic vasculature between pulsatile flow and nonpulsatile flow. Cannuale with 25, 50, and 75% diameter stenosis (DS) were located at the outlet cannula. Using the Korea Hybrid ventricular assist device (KH-VAD) (pulsatile pump: group A) and Biopump (nonpulsatile pump: group B), constant flow of 2 L/min was maintained then real-time flow and velocity in the proximal and distal part of the stenotic cannula were measured. The hemodynamic energies of two groups were compared. At 75% DS, proximal energy equivalent pressure (EEP) delivered to the distal end was only 41.9% (group A) and 42.5% (group B). As the percent EEP fell below 10%, pulsatility disappeared from the 50% stenosis in group A. The surplus hemodynamic energy (SHE) of group B at all degrees of stenosis must have been 0, which was also the case of group A at 75% stenosis. This research evaluated the hemodynamic energy on various degrees of DS in both pulsatile and nonpulsatile flow with mock system. Using a pulsatile pump, pulsatility disappeared above 50% DS while hemodynamic energy was maintained. Therefore, our results suggest that pulsatile flow has a better effect than nonpulsatile flow in reserving hemodynamic energy after stenotic lesion.     

Pediatric physiologic pulsatile pump enhances cerebral and renal blood flow during and after cardiopulmonary bypass

Controversy over benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) continues. Our study objectives were to first, quantify pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and second, investigate effects of pulsatile versus nonpulsatile flow on cerebral and renal blood flow, and cerebral vascular resistance during and after CPB with deep hypothermic circulatory arrest (DHCA) in a neonatal piglet model. Fourteen piglets underwent perfusion with either an hydraulically driven dual-chamber physiologic pulsatile pump (P, n = 7) or a conventional nonpulsatile roller pump (NP, n = 7). The radiolabeled microsphere technique was used to determine the cerebral and renal blood flow. P produced higher hemodynamic energy (from mean arterial pressure to EEP) compared to NP during normothermic CPB (13 +/- 3% versus 1 +/- 1%, p < 0.0001), hypothermic CPB (15 +/- 4% versus 1 +/- 1%, p < 0.0001) and after rewarming (16 +/- 5% versus 1 +/- 1%, p < 0.0001). Global cerebral blood flow was higher for P compared to NP during CPB (104 +/- 12 ml/100g/min versus 70 +/- 8 ml/100g/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brainstem, blood flow resembled the global cerebral blood flow. Cerebral vascular resistance was lower (p < 0.007) and renal blood flow was improved fourfold (p < 0.05) for P versus NP, after CPB. Pulsatile flow generates higher hemodynamic energy, enhancing cerebral and renal blood flow during and after CPB with DHCA in this model.     

Effects of pulsatile cardiopulmonary bypass on the renin-angiotensin-aldosterone system following open heart surgery

The effects of pulsatile cardiopulmonary bypass on the renin-angiotensin-aldosterone system and tissue metabolism, especially those which occur soon after surgery, were studied in 26 patients who required total cardiopulmonary bypass for longer than 60 minutes. These patients comprised 11 who underwent open heart surgery utilizing nonpulsatile cardiopulmonary bypass (Group I) and 15 who underwent open heart surgery utilizing pulsatile cardiopulmonary bypass (Group II). Plasma angiotensin II and serum aldosterene levels were significantly increased one and 5 hours postoperatively in Group I when compared with the preoperative values, whereas no significant elevations were observed in Group II. Plasma angiotensin II and serum aldosterone levels one hour postoperatively in Group II were significantly lower than those in Group I. Lactate levels in the arterial blood were significantly elevated, one and 5 hours postoperatively in both Groups I and II. Moreover, no significant difference was observed in the lactate levels between Groups I and II, one hour postoperatively. In the nonpulsatile group (Group I), plasma angiotensin II levels one hour postoperatively were correlated significantly with the duration of total cardiopulmonary bypass. In conclusion, pulsatile cardiopulmonary bypass offers significant advantages in terms of lower plasma angiotensin II and serum aldosterone levels, when compared with nonpulsatile cardiopulmonary bypass soon after open heart surgery requiring total cardiopulmonary bypass for longer than 60 minutes, however, it does not offer a definite advantage for tissue metabolism.     

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.     

Pulsatile Augmentation Device for Extracorporeal Circulation

Abstract: A device has been designed, constructed, and tested to provide pulsatile pressure/flow to a standard extracorporeal bypass circuit. The pulsatile augmentation device is pneumatically driven similar to an artificial heart ventricle except that there are no valves. It is constructed of polyurethane by vacuum forming and high frequency welding. Drivers used are a modified Arrow-Kontron in-traaortic balloon pump or the Utah artificial heart driver. In vitro testing with fresh bovine blood demonstrated acceptable blood compatibility and hemodynamic function. In vivo testing for 4 h in a right and left heart extracorporeal bypass circuit showed good pulse augmentation in pulmonary and systemic bypass circuits. The device shows promise for adding pulse to standard cardiopulmonary bypass and to extracorporeal right heart circulatory assist circuits.     

体外循环心脏手术相关因素致肌钙蛋白T变化的研究

目的 观察体外循环心脏手术相关因素致心肌细胞的损害程度,通过心肌肌钙蛋白Ｔ变化找出其相对规律及数据,为临床提供心肌保护措施及理论根据。方法 随机选择３７例心脏手术,其中心脏瓣膜替换术１５例,先天性心脏病１５例,冠状动脉搭桥７例,于手术前、停机时、术后５ｈ、术后第１天、术后第２天抽 血检测肌钙蛋白Ｔ浓度的变化经统计学处理,ｑ检验进行对比研究。结果 （１）主动脉阻断时间〉６０ｍｉｎ组术后５小时肌钙蛋白     

Cognitive dysfunction after cardiopulmonary bypass

Cognitive dysfunction remains a significant complication after cardiopulmonary bypass, despite continuous improvement in the overall outcome in open‐heart surgery. Embolization of the atheromatous material, most notably during removal of the aortic clamp, is a major cause. Strategies have been developed to minimize cerebral embolization. Modified surgical techniques include the use of hypothermic circulatory arrest, venting of the left ventricle, minimizing aortic manipulation, and the use of epiaortic ultrasound to locate and avoid trauma to the aortic atheromatous plaque. Use of an intra‐aortic filter has been shown recently to reduce intraoperative cerebral embolic events and improve postoperative neurocognitive outcomes. Off‐pump coronary artery bypass technique has also been claimed to have lower neurological complications, which is probably attributable to the avoidance of aortic cannulation and cardiopulmonary bypass. Its role on cerebral protection is, however, debatable. Chinese Abstract

Figure Chinese Abstract Open in figure viewer PowerPoint

Volume 6 , Issue 1 February 2002

Pages 1-3     

术中静脉注射胺碘酮对体外循环冠状动脉旁路移植术患者转归的影响

目的 评价术中静脉注射胺碘酮对体外循环冠状动脉旁路移植术患者转归的影响.方法 择期行体外循环冠状动脉旁路移植术的患者34例,ASA Ⅱ或Ⅲ级,年龄43～64岁,体重51～95kg,随机分为2组(n=17):对照组(C组)和胺碘酮组(A组).体外循环开始后,A组静脉注射胺碘酮5 mg/kg,C组注射等容量生理盐水.记录术毕至出院期间房颤的发生情况、术毕至首次发生房颤的时间、ICU停留时间和术毕至出院的时间.结果 两组ICU停留时间、术毕至出院时间、术毕至首次发生房颤的时间比较差异无统计学意义(P>0.05),A组房颤发生率低于C组(P<0.05).结论 术中静脉应用胺碘酮可在一定程度上预防体外循环冠状动脉旁路移植中患者术后房颤的发生,改善转归.     

Comparison of parameters for detection of splanchnic hypoxia in children undergoing cardiopulmonary bypass with pulsatile versus nonpulsatile normothermia or hypothermia during congenital heart surgeries

The aim of this study is to evaluate gastric mucosal oxygenation together with whole-body oxygen changes in infants undergoing congenital heart surgery with cardiopulmonary bypass (CPB) procedure and the use of either pulsatile or nonpulsatile mode of perfusion with normothermia and pulsatile or nonpulsatile moderate hypothermia. Sixty infants undergoing congenital cardiac surgery were randomized into four groups as: nonpulsatile normothermia CPB (NNCPB, n = 15), pulsatile normothermia CPB (PNCPB, n = 15), nonpulsatile moderate hypothermia CPB (NHCPB, n = 15), and pulsatile moderate hypothermia CPB (PHCPB, n = 15) groups. In NNCPB and PNCPB groups, mild hypothermia was used (35°C), whereas in NHCPB and PHCPB groups, moderate hypothermia (28°C) was used. Gastric intramucosal pH (pHi), whole-body oxygen delivery (DO(2)) and consumption (VO(2)), and whole-body oxygen extraction fraction were measured at sequential time points intraoperatively and up to 2 h postoperatively. The measurement of continuous tonometry data was collected at desired intervals. The values of DO(2), VO(2), and whole-body oxygen extraction fraction were not different between groups before CPB and during CPB, whereas the PNCPB group showed higher values of DO(2), VO(2), and whole-body oxygen extraction fraction compared to the other groups at the measurement levels of 20 and 60 min after aortic cross clamp, end of CPB, and 2 h after CPB (P < 0.0001). Between groups, no difference was observed for pHi, lactate, and cardiac index values (P > 0.05). This study shows that the use of normothermic pulsatile perfusion (35°C) provides better gastric mucosal oxygenation as compared to other perfusion strategies in neonates and infants undergoing congenital heart surgery with CPB procedures.