Hemolytic characteristics of three suctioning systems for use with a newly developed cardiopulmonary bypass system.

INTRODUCTION: We have been developing a closed-circuit cardiopulmonary bypass (CPB) system ("Dihead CPB") for application during coronary artery bypass grafting (CABG) and valve surgery. To strive for minimal hemolysis during Dihead CPB, we compared the hemolysis caused by three different suction systems and performed a clinical study with the newly applied suction system. MATERIALS & METHODS: We evaluated the hemolysis caused by roller-pump suction, the SmartSuction® Harmony® and wall suction systems with respect to suction speed and compared the systems by means of in vitro studies. A clinical study was also performed on 15 volunteers to assess hemolysis and the adequacy of the newly applied suction system with Dihead CPB. RESULTS: Pressure inside the suction cannula was -22.5 ± 0.1 mmHg at a maximum flow of 1.5 L/min for roller-pump suction and -43.4 ± 0.1 mmHg at -150 mmHg of the set vacuum pressure of wall suction. With the SmartSuction, the pressure inside the cannula varied from -76.3 ± 1.0 to -130.3 ± 1.5 mmHg, depending on suctioning conditions. Suction speed (to suction 50 ml of blood) was fastest with the SmartSuction (69.7 ± 3.58 s) whereas, with roller suction, it was 117.3 ± 8.47 s and with wall suction 96.9 ± 7.10 s. The SmartSuction had the highest hemolysis rate (2.00 ± 0.33%) vs. 0.61 ± 0.10% for roller suction and 0.41 ± 0.11% for wall suction (p<0.001). The clinical study with wall suction showed no significant increase in plasma free hemoglobin during or after CPB compared with before surgery. CONCLUSIONS: Wall suction had less hemolysis than roller suction or the SmartSuction in the in vitro study and the clinical study with wall suction showed efficient suction speed and acceptable hemolysis, suggesting that Dihead CPB with wall suction is feasible for CABG.

Use of a Modified Cardiopulmonary Bypass Circuit for Suction Embolectomy with the AngioVac Device.

The AngioVac suction cannula and circuit were designed for the percutaneous removal of soft thrombus and emboli in procedures requiring extracorporeal circulatory support. We describe a modification of the AngioVac suction catheter and cardiopulmonary bypass (CPB) circuit to effectively remove thrombus while maintaining the ability to rapidly initiate full CPBs during a medical crisis. This article will discuss the design concepts of the modified circuit as well as procedural protocols and considerations. The design modifications of incorporating an oxygenator, reservoir, and bridge allow for an increased flexibility that allows adaption to veno-venous extracorporeal membrane oxygenation or full CPB support when required for oxygenation or hemodynamic support.

Low-prime system minimizes transfusions and hemodilution in coronary bypass.

Standard heart-lung machines lead to substantial hemodilution with associated impaired organ function and increased need for blood transfusions. The aim of this study was to evaluate the effect of the new PRECiSe low prime volume system on perioperative myocardial damage, hemodilution, and transfusions. In a case-matched prospective study, 40 patients undergoing coronary artery bypass surgery using PRECiSe were compared with 40 patients on a standard heart-lung machine. In the PRECiSe group, the prime volume was significantly reduced, resulting in less hemodilution and transfusion requirements during and after extracorporeal circulation: only 10% of patients needed transfusions vs. 35% in the control group, with an average transfusion need of 0.16 vs. 1.25 units. There were no significant differences in perioperative cardiac-specific enzymes. The PRECiSe system was considered safe and effective for coronary artery bypass surgery.

Perfusion safety: defining the problem.

Perfusion safety is not an isolated component of cardiac surgery, but encompasses many facets, including equipment, safety devices, conduct of perfusion, surgical technique, vigilance, and communication within the operating room. Over the last 25 years, several surveys have provided an estimation of the occurrence of perfusion-related incidents and documented the frequency with which they affected patient morbidity and mortality. As the focus of attention turned to correcting these problem areas, each subsequent survey demonstrated changes, but also pointed out new areas needing improvement. As technology and education improved, so did results. With refinements in perfusion equipment and techniques, and increasing use of computer assistance and automation, cardiopulmonary bypass should become even safer. The key ingredient, though, will remain the knowledge and expertise of the perfusionist.

Standards update on perfusion equipment and practice.

Standards applying to the manufacture, testing and labeling of perfusion components and equipment, as well as those dealing with clinical use of extracorporeal circulation, have been promulgated by both standards-setting organizations and professional organizations. The rationale and purpose for device standards are discussed, and many organizations and the processes involved in developing standards are described. Perfusion checklists used during equipment set-up, use and at termination have a long track record of acceptance by clinicians. Evolving techniques have prompted revisions to the basic perfusion checklist, which should be considered a guide for development of institution-specific checklists. Current and future work by international standards-setting organizations is described.

The Geat Britain and Ireland perspective: current perfusion safety issues, preparing for the future.

The Great Britain and Ireland (GBI) recommendations for standards of monitoring and alarms during cardiopulmonary bypass (CPB) came into force in January 2004. While perfusion departments in Great Britain and Ireland should now have a good baseline level of safety, it is important that department-specific safety is also considered. Patient safety is paramount, but safety within our speciality must also take into account the protection of the perfusionists' health and the protection of their careers. These different aspects of safety are fundamentally interrelated. This paper focuses on the importance of careful assessment, implementation and documentation when a new component or technique is being introduced to the CPB circuit, even when the aim is to increase safety. Knowledge of the civil justice system and the trends in medical negligence claims are an integral part of perfusionist safety. Perfusion in Great Britain and Ireland is rightly striving for professional recognition from the Health Professions Council (HPC). As we raise the profile of perfusion, we educate more people about the importance of our role and level of responsibility within the cardiac operating team. This will increase the potential for medical negligence claims to be directed specifically at our speciality. All these issues are discussed in detail.

Manufacturers' approaches in the development of intelligent multilevel safety systems to assist perfusionists during cardiopulmonary bypass.

How safe is safe? The design intent of perfusion safety systems is to offer maximum flexibility, low-cost and failsafe features. While easily said, these requirements are difficult to deliver in a perfusion world where standardization is uncommon. This paper reviews the challenges all manufacturers face as they strive to offer the ultimate in safety, keeping the price affordable for the technology deployed and the usability common sense for the perfusionist using the equipment. As microprocessors are able to assist designers in providing intelligent, multilevel safety systems, care must be taken during the design process to balance technological ability with intuitive use. In the final analysis, however, it is the perfusionist who is the primary safety system, and the technology is his or her backup.

Centrifugal pump and reduction of neurological risk in adult cardiac surgery.

This study was performed to assess if the kind of pump used for CPB (roller vs. centrifugal) can influence neurological outcomes of adult cardiac surgery patients. Between 1994 and 1998, 3438 patients underwent coronary and/or valve surgery at our hospital; of these, 1805 (52.5%) underwent surgery with the use of a centrifugal pump, and 1633 (47.5%) were operated with a roller pump. The effect of the type of the pump and of common preoperative and intraoperative risk factors for five different neurological outcomes (permanent neurological deficit, coma, delirium, transient neurological deficit, overall neurological complications) were assessed with univariate and multivariate analyses in the whole patients population, in patients > or = 75 years old and in patients with histories of previous neurological events. Centrifugal pump use was the only protective factor for perioperative permanent neurological deficit in multivariable models developed for the whole patient population and for patients > or = 75 years old. In addition, it resulted as the only protective factor for perioperative coma occurrence in multivariable models developed for patients > or = 75 years old, and for patients with histories of previous neurological events. The use of the centrifugal pump provided a risk reduction for the considered events ranging from 23 to 84%. Centrifugal pump use can be helpful in reducing the occurrence of some of the most feared neurological complications of adult cardiac surgery patients.

[Dampness in an electric plug as a cause of electricity failure in an operation theatre]. / Fugt i el-stik medfører el-udfald på operationsstue.

Two cases of electricity failure in an operation theatre during open heart surgery are discussed. The fuse for the patient monitor, ventilator, surgery instruments and heart lung machine was blown. Short-circuit was established because of humidity in the plug of the heater for fluid and blood. We recommend sealed or founded plugs and that anaesthesia equipment should not be used as an electrical supply for other electronic apparatus.

[Development of a novel artificial heart-lung system for long-term cardiopulmonary support--experimental evaluation in goats with total cardiopulmonary bypass].

A novel cardiopulmonary support (CPS) system for long-term use was designed and evaluated. The CPS system consists of an air-driven ventricular assist device (VAD) and a newly developed compact membrane oxygenator (MO). The VAD had proven durable and antithrombogenic in over 200 clinical uses. The membrane oxygenator, with a membrane area of 1.2 m2 and priming volume of 140 ml, is compact and designed to be interposed in the VAD conduit. It is made with a special hollow fiber membrane, in which micropores are blind-ended so that serum leakage can be prevented during prolonged use. The blood contacting surface of the MO is heparinized with a newly developed covalent bonding technique that ensures good thrombus resistance. Chronic animal experiments of total CPS were carried out for up to 336 hr in seven goats weighing from 28 to 36 kg. Venoarterial bypass was instituted with the CPS system in which all venous blood was drawn from both the right atrium and ventricle and returned to the aorta. No systemic anticoagulant therapy was used, except for a heparin-added fluid infusion to keep the monitoring lines open. Blood flow rate ranged between 107 to 130 ml/kg/min, oxygen transfer between 142 to 174 ml/min, and carbon dioxide removal between 78 to 148 ml/min. No plasma leakage was observed at the hollow fiber membrane. Substantial changes were not found in platelet count or other coagulation factors. And no perceptible thromboembolism was found at necropsy in any case. These results indicate that the system is competent enough to be used for long-term CPS, such as a bridge to lung or heart-lung transplantation.

Biomaterials and cardiovascular devices.

In the field of cardiovascular surgery there is presently a lack of biomaterials possessing essential characteristics of the native tissue or organ which is to be replaced. This paper describes various biomaterials that have been introduced into the circulatory system and the complex reactions that subsequently occur. The risk of infection is also discussed as well as prevention and treatment regimes that can be used. Examples of future biomaterial development are outlined in an attempt to achieve biocompatibility.

The total artificial heart.

In the early 1800s, an awareness of potential ventricular failure stimulated interest in artificial heart replacement. In 1937 the first total artificial heart (TAH) was implanted into the chest of a dog by Russian physicians. The primary driving force for mechanical cardiac assistance developed from the necessity for circulatory assistance in order to perform corrective cardiac surgery. In 1953 the first successful closure of an atrial septal defect using extracorporeal circulation was performed. During the following decade the concept of using mechanical devices to assist the failing heart was aggressively pursued. This culminated in the first implant of a TAH in a human in 1969 as a bridge to transplant. Clinical implant of the TAH as a permanent device was performed in 1982 by researchers at the University of Utah. This patient lived for 112 days. Three successive permanent implants were performed in Louisville, Kentucky, with one patient surviving for 620 days. All of these permanent TAH patients suffered from device-related complications including bleeding, infection, and thromboembolic events. It became apparent that the present configuration of the TAH with its external drive lines and large air console was not ideal for long-term support. In 1985 the first implant of the Symbion J-7-100 TAH (Jarvik-7) as a bridge to transplant was performed. This patient was supported by the device for 9 days and was successfully transplanted and discharged home. Since 1985 more than 170 patients have been bridged using the Symbion J-7 TAH with more than 70% of these patients being successfully transplanted. The incidence of thromboembolic events has dramatically reduced with better understanding of anticoagulation requirements. Infection continues to be the greatest potential complication with these patients. In spite of this, the pneumatic TAH has proved to be an adequate bridge to transplant device.