Perfusion safety: Past, present, and future

Perfusion Safety: Past, Present, and Future David A. Palanzo, CCP

Safe cardiopulmonary bypass has been paramount from its first use in the early 1950s until the present. The original perfusion circUits incorporated complex feedback loops and multiple safety devices. As circuits improved and became simpler to operate, advances in safety did not always keep pace. Surveys have illustrated areas that needed improvement and extra attention has been focused on those problems. As the field of perfusion evolved, so has the perfusionist. Perfusion has progressed from on-the-job training to formalized training, certification, and accreditation, and is now approaChing national standardization. As the computer

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ERFUSION SAFETY is a multifaceted topic covering a broad range of subjects. This is not merely referring to safety devices, but everything that encompasses safe cardiopulmonary bypass (CPB). This includes heart-lung machines, circuit design, equipment used. perfusion practices, surgical techniques, in addition to such things as the education of the peffusionist, his or her alertness and attention to the events occumng simultaneously within the operating room, and the communication among the surgeon, anesthesi01ogist/nurse anesthetist, and the perfusionist. In the 45 years since the first use of CPB. many improvements have been made in the equipment used within the bypass circuit. However. there is not a totally safe replacement for the heart and lungs. Part of the problem arises from the complexities of trying to have extracorporeal circulation (ECC) mimic the human anatomy and physiology. In the past. as technology advanced, the safety of these new techniques and devices did not always keep pace. To address the variety of issues that have improved the safety of CPB over the years, such as oxygenation, filtration, biocompatibility, and surgical technique, is beyond the scope of this article. This report reviews safety in general, its importance as expressed in the literature and in user-surveys, as well as what they have reported. Some other important areas that will lead to even safer systems in the future are also examined. BRIEF OVERVIEW OF HISTORICAL ADVANCES iN TECHNOLOGY

The initial heart-lung machines were quite complex and contained fail-safe mechanisms and other safety features such as oxygenator blood level sensors? level floats, 2 and pressure sensors. Most of these machines were custom-built and required large amounts of time and elaborate detail to prepare them for use. As the number of procedures and cardiac surgery programs increased, it became necessary for the development of a simpler system. Large stainless steel devices with rotating discs were replaced with roller pumps and disposable equipment. Early membrane oxygenators gave way to hard-shell bubble oxygenators. With the advent of coronary artery bypass surgery, the number of cardiac surgical programs dramatically increased. At this tim e , industry became heavily involved in this rising allied health field, and the production of new CPB equipment flourished. With the risk of massive air embolism and other neurological effects of CPB, filtration was the next big area of improvement.

age proceeds, the use of safety devices and feedback mechanisms whose developments have been aided by the newly available technologies increases. As the 21st century approaches, cardiopulmonary bypass will continue to become safer, but the perfusionist must continue to stay up-to-date in education and remain vigilant while in the operating room.

Copyright © 1997 by W.B. Saunders Company KEY WORDS: safety, cardiopulmonary bypass surveys, perfusion certification/accreditation Also at this time, more attention to monitoring anticoagulation became apparent, further decreasing embolization and coagulopathies. After much research and many clinical comparisons, hollowfiber membrane oxygenators have been shown to be superior to bubble oxygenators and are used by most of the institutions doing cardiac surgery today. A similar Pattern was seen with the introduction of the centrifugal pump, because of its resistance sensitivity, decreased risk Of passing gross air, and its less traumatic blood handling than the standard roller pump. In more recent years, much attention has been paid to reperfusion injury and the systemic inflammatory response seen postoperatively. Heparin-coated circuits to improve biocompatibility and leukocyte removal are two areas that have been developed to reduce these adverse effects of CPB. Along with this evolution in perfusion equipment has come advances in both surgical and perfusion techniques, making cardiac surgery and CPB safer. Alpha-stat blood gas management, retrograde cerebral perfusion, and modified ultrafiltration are just a few of the more recent techniques that have become somewhat standard in perfusion practice. SAFETY IN THE LITERATURE

Although most articles concerning CPB techniques and equipment imply patient safety, only a Small percentage of them deal specifically with perfusion safety. A recent search through a database (PerfSearch, property of American Academy of Cardiovascular Perfusion and its use is limited to its members) that is specific for CPB-related manuscripts appearing in journals from cardiac surgery, anesthesiology, cardiology, perfusion, biomedical engineering, and other sources found a surprisingly low number Of articles covering specific information on safety or accidents. Of the more than 12,000 manuscripts in the database, only 165 (1.4%) addressed the issue Of safety. Most of these papers dealt with air embolism, and some were reviews that included air accidents. Fifty-four articles (approximately 0.45 % of the total database) reported on safety devices or issues other than gaseous micr6emboli. The earliest articles by Senning3 (1952) and Glenn and

From the Lehigh Valley Hospital, Allentown, PA. Address reprint requests to David A. Palanzo, CCP, Perfusion Department, Lehigh Valley Hospital, Cedar Crest & 1-78, Allentown, PA 18105. Copyright © 1997 by W.B. Saunders Company 1053-0770/97/1103-001653.00/0

Journal of Cardiothoracic and Vascular Anesthesia, Vol 11, No 3 (May), 1997: pp 383-390

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SewelP (1953) addressed the prevention of air embolism. By the late 1950s and early 1960s, there were articles on flowmeters, 5 safety devices for ECC. 6 mechanical failure during ECC. 7 and a left ventricular vent valve. 8 Topics in the 1970s were few but covered the areas of aortic vents in the prevention of air embolism. 9 retrograde dissection during CPB.I° halothane removal, I1 and runaway pumphead. 12 The 1980s saw a large increase in the number of reports on safety, partly because of the mcreased number of programs and individuals performing cardiac surgery. Stoney et al's 13 report on air embolism and other accidents that occurred from 1972 through 1977 and Mills and Ochsner's 14 manuscript on massive air embolism during CPB both had a huge effect on the attention that safety received during the next decade. There were reports on power failures 15,16 and emergency drive systems, t7 Reviews on the risks and hazards of CPB 18-22 appeared at several different times during the 1980s along with several accident surveys. 23-25 Preventive maintenance. 26,27 oxygenator failure. 28 safety devices for level regulation. 29 and pressure measurement 3°,31 were other topics that were reported. In 1980. Christman and Kurusz 32 reviewed the safety devices available at that time for preventing massive gas embolism during CPB. They divided the devices into four categories: devices that attach to oxygenators" devices used proximal to the pumphead: a device that functions as a blood pump; and devices used distal to the pumphead. Hill and Lefrak 33 presented a review of the available devices to monitor conditions of CPB in 1985. The authors stated that human error was still the major component in perfusion-related accidents and complications. The perfusionist needs to maintain the knowledge and understanding of new equipment and techniques. The safe conduct of perfusion depends most heavily upon a well-trained, ever-vigilant perfusionist, but that alone will not guarantee success. Safety devices, if used properly, may prevent or predict an upcoming problem. The use of new equipment and techniques may not demand as narrow an operating margin as older equipment and techniques once required. While most operative situations do not require the maximum ability of all team members or the full capability of their equipment, a few situations will arise where one's knowledge, judgment and the use of safety devices will make the ultimate difference. Kriewal134 addressed the many facets of safe CPB, ranging from practices, equipment, human factors, and cost in his manuscnpt on safety systems in perfusion. It is important to note that in 1987 the American Academy of Cardiovascular Perfusion held a panel discussion covering the many aspects of perfusion safety at its annual meeting. 3s-39 Similarly, the journal Perfusion devoted an entire issue to perfusion safety in 1988. 40-44 During the early to mid-1990s, there were reports on risk management45 and quality assurance. 46 issues that received much attention in the late 1980s and early 1990s. which continues into the present. Air handling of membrane oxygenators 47 and reports on the new one-way valves for centrifugal pumps 48,49 began appearing in the literature in 1994 and 1995. Over the years, the evolution of cardiac surgery techniques and CPB have made cardiac surgery extremely safe. Even though air embolism was one of the first concerns or the early

pioneers in cardiac surgery, it is unfortunate that there are still reports of massive air embolism 5° occurring in the 1990s. If the textbooks on cardiopulmonary bypass are examined, a similar trend in attention to safety emerges. In Galletti and Brecher's t text of 1962, Heart-Lung Bypass, there is no specific section on safety. Ionescu 51 included chapters by the "world's leading cardiac surgeons" in the second edition of his text entitled Techniques in Extracorporeal Circulation, but none of them dealt solely with safety. 51 Cardiopulmonary Perfusion, 52 a book that served as the main textbook for most perfusion training programs for a number of years, was first published in 1975. This book covered all aspects of perfusion, including anatomy and physiology, pharmacology, circuit design, equipment, and perfusion conduct. Appropriately, a chapter entitled "Accidents and Safeguards" was added for the second edition in 1985. 53 In 1986, Cardiopulmonary Bypass." Principles and Management, 54 a tex t edited by Taylor, included a final chapter on safety during CPB, which contained sections on bypass safety, accidents, coagulopathies, mechanical and electrical failures, perfusion management, and safety for the perfusionist. Safety and Techniques in Perfusion by Reed, Kurusz and Lawrence, 55 was published in 1988. By its title alone it can be seen that the entire focus of this text was on perfusion safety. By the early 1990s, safety issues had becom e closely tied to most aspects of CPB. This is evident by examining Cardiopulmonary Bypass.: Principles and Practice (published in 1993) edited by Gravlee, Davis and Utley.56 The thread of safety runs through several of the chapters, especially those on emb01ic events, anticoagu!ation, and the conduct and monitoring of CPB. S U RVEYS

The first national survey on cardiopulmonary bypass-related complications was published in 1980. 13 The Stoney report was a retrospective survey sent to cardiac surgeons and covered the 6-year period from 1972 to 1977. Three hundred forty-nine surgeons who collectively performed 374,819 operations responded. The survey included several questions that inquired about episodes of arterial line air embolism, disseminated intravascular coagulation (DIC), oxygenator failure mechanical failure of the pump, and electrical failure of the pump. Arterial line air embolism and DIC were the two most common problems. A total of 1,419 accidents were reported, resulting in 100 permanent injuries and 264 deaths. It is probable that these results are an underestimation of the total accidents that occurred during this period, because the respondents were asked t o supply information based on memory, an approximation at best. During this 6-year period, an accident related to the pump 0xygenator system occurred once in every 300 procedures. Accidents resulting in permanent injury or death occurred once in every 1,000 procedures. Recommendations to reduce the incidence of problems included the use of prebypass checklists, preventive maintenance of CPB equipment, alarms for air embolism, and monitoring of !ieparin levels with activated coagulation times (ACT). A review of massive air embolism accidents by Mills and Ochsner t4 was also published in 1980.14 They reported on 13 cases (of 3,620 cardiac procedures) of massive air embolism in which lack of attention to the oxygenator reservoir level by the perfusionist was the major cause of the accident. The authors

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recommended mandatory attention to the oxygenator blood level during CPB and use of a blood level sensing device in the bypass circmt. After the publication of the Stoney report, a similar retrospective survey was undertaken in the United Kingdom by Wheeldon. covering the years 1974 to 197923 and repeated in 1980. 24 The results of the first survey were similar to that of Stoney, with serious incidents occurring about once every 300 perfusions and permanent injury or fatality occurring once every 1,500 perfusions. There was an increase in the incidents reported in the 1980 survey, with a serious incident occurring every 140 perfusions, although the cases of permanent injury or fatality had dropped to once every 1,800 perfusions. Similar to the earlier American study, the major problems were arterial line embolism and consumptive coagulopathies. The most frequently occurring incident, though, was "inadequate oxygenation." which covered reduced oxygenator performance or impaired perfusion (Table 1). In 1980. Miller et al57 sent 929 surveys to perfusionists an North America and asked each team to return one survey. The survey dealt with equipment and techniques used during 1979. Two hundred ninety-one teams (811 perfusionists) performing 108,000 adult cardiac cases responded. Arterial line filters were used by 64% of those surveyed, whereas most used them primarily as a bubble trap. Prebypass filters were used by 50% of the groups. Membrane oxygenators were used occasionally by 40% of the respondents and exclusively by 5%. Low-level alarms were used by 45% of the groups in the survev, and 25% of the groups used some type of POJPCO2 sensors. Eighty percent of the groups used ACT measm'ements to check for the adequacy of heparinization, and 49% of the groups used written perfusion protocols. A survey concerning filtration during cardiac surgery was conducted by Kurusz et a158 in 1982, with the results being published in 1983. s8 The survey was mailed to 993 Certified Clinical Perfusionists in the United States and Canada. Sixtyfive percent ~647) of the questionnaires, representing 148.829 cardiac cases, were returned. Seventy-eight percent of the respondents used arterial filtration, and 63% used a prebypass filter. Of those who used arterial line filters. 99.6% believed that they were necessary with bubble oxygenation, and 85% thought that they were necessary with a membrane oxygenator. Blood coagulation was routinely monitored during CPB by 96.7% of the respondents, with 56.8% using the ACT measurement. In 1986. a comprehensive perfusion accident survey by Kurusz et a125 was published. The questionnaire covered the years 1982 to 1985 and asked questions concerning specific CPB complications and patient outcomes. Of the 1.366 surveys

mailed. 608 surveys were returned involving 573.785 procedures over the 3-year period. The overall incidence rate for a complication or accident was about once every 100 procedures (1%) when all 15 types of accidents posed in the survey were considered. Permanent injury or death from all types of complications during CPB occurred once every 1.000 procedures (0.1%). The most common problems were protamme reaction, hypoperfusion due to inadequate blood flow. gas embolism, and errors in drug administration. Disseminated intravascular coagulopathy was the most common complication in the Stoney survey and second most frequent cause of mortality in the Wheeldon survey, but ranked 13th out of 15 in occurrence and eighth for morbidity or mortality in the Kurusz sutvey. Protamine reaction ranked first in both occurrences and a patient outcome of permanent injury or death. Air or gas embolism ranked as the third leading cause of morbidity or mortality during bypass. When asked about safety devices used to prevent massive gas embolism. 84% of the respondents said that they used an arterial line filter. 70% used a one-way pressure relief valve in the vent and 3% used no safety devices. A prebypass checklist was used by 77.5% of the respondents. Sixty-one percent checked off the list mentally whereas 39% had some form of written checklist. Forty-nine percent of the respondents had written perfusion protocols (Table 2). The Perfusion Quality Committee of the American Society of Extra-Corporeal Technology (AmSECT) conducted a perfusion practice survey in the fall of 1993. 59 Surveys were mailed to 940 medical centers with heart programs in the continental United States. Sixty-four percent (588) of the program returned useable questionnaire, with a cumulative caseload of 270.426 procedures for the 1992 calendar year. Activated coagulation times were used by 99% of the programs that responded for measuring the adequacy of heparinization Subsequent doses of heparin were also determined by ACTs by 92% of the respondents. Body surface area was used to determine calculated blood flow before CPB by 93.5% of those responding, and 465 out of 589 respondents chose venous saturation as the most important parameter routinely used to determine appropriate blood flow rate. Ninety-seven percent of those who responded used an arterial line filter. 60% used a blood level sensor, and 79% used a bubble detector in the extracorporeal circuit. A one-way valve in the intracardiac vent or sump was employed by 72% of the respondents. Seventy-eight percent of the groups thai responded maintained a policy and procedure manual, although 68.5% of the groups participated in the quality management process at their institution.

Table 1. Accident Surveys Results Survey

Stoney 13

Reporting years Occurrence of pump-related accident Occurrence of permanent injury or death Major accidents

1972-1977 1/300 1/1,000 Air embolism DIC Mechanical, electrical, and 0xygenator failure

Abbreviation: DIC, disseminated intravascular coagulopathy,

w h e e l d o n 23

Wheeldon 24

1974-1979 1980 1/400 1/140 1/1,500 1/1,800 Air embolism DIC Inadequate perfusion

Kurusz 25

1982-1985 1/100 1/1,000 Protamine reaction Hypoperfusi0n Gas embolism

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DAVID A. PALANZO

Table 2. Surveys Summary Survey

Stoney 13

Miller 57

Kurusz5s

Kurusz2s

Practice (AmSECT)59

1980 1972-1977 1700 349 374,819

1982 1979 929" 291" (811) 108,000

1983 19~32 993 646 148,829

1986 1982-1985 1366 608 573,785

1994 1992 940 588 270,426

--

86%

97%

--

99%

Arterial line filters

--

64%

78%

81%

97%

Low-level alarms

42%

--

--

70%

60%

Activated coagulation t i m e s (s)

63%

80%

57%

--

99%

--

49%

--

49%

78%

Published Reporting years Questionnaires mailed Respondents Total caseload % of respondents Measuring Adequacy of heparinization Using

Written protocols

*Two hundred ninety-one teams responded, representing 811 perfusi0nist s.

In a survey of the attendees of the 1995 San Diego Cardiopulmonary Bypass Symposium6° (Pathophysiology and Techniques of Cardiopu!monary Bypass: XVI), 283 attendees answered questions related to centrifugal pumps. Eighty-six percent of the respondents were perfusionists, 7% were cardiac surgeons, and 4% were anesthesiologists. Of those who responded, 72% used centrifugal pumps at their institutions. Centrifugal pumps were used for routine CPB cases in 49% of the group for adults and 7% for pediatric cases. When asked if they had ever experienced a perfusion accident or problem related in any way to using the centrifugal pump or roller pump, the attendees responded 29% and 47%, respectively. Pump failure or malfunction that resulted in patient injury or death was experienced by 4% and 1% of the attendees for centrifugal pumps and 8% and 4% for roller pumps. In a report by Kolff et a161 on centrifugal pump failures, surveys were sent to 2,424 Society of Thoracic Surgeons' members, with 285 members who use centrifugal pumps responding. Twenty-one percent of the respondents reported 108 malfunctions, including 46 complete pump fai!ures. Twentyone percent of the surgeons reported that their perfusionists have forgotten to clamp the pump line, resulting in backflow. The authors recommended the use of a one-way flow valve in the arterial line to prevent backflow and its potential risks. COMPUTER-ASSISTED

CARDIOPULMONARY

BYPASS

As mentioned earlier, the initial extracorporeal circuits included many safety devices and elaborate feedback mechanisms. Many of the early designs incorporated blood level sensors that automatically controlled the blood volume in the reservoir at all times. 62 Some heart-lung machines employed servoregulated roller pumps, 63 and others had devices to automatically control the ventilating gas mixture using a pH sensor in the blood[64As extracorporeal circulation moved from the researc h laboratory into the clinical arena, from teaching facilities to community hospitals, a less complicated, less expensive means to perform CPB for the ever-increasing number of cardiac surgery procedures and programs was necessary. By the late 1970s and early 1980s, many bypass circuits were quite simplistic, being composed of an oxygenator! heat exchanger roller pump, and tubing The individual running the pump was solely responsible for conducting a safe and

effective perfusion. As the risk of gas embolism became more apparent, some safety devices such as biood level sensors and bubble detectors were added to the simple circuit. These devices in themselves were limited computer systems aiding the perfusionist during CPB. Newer designs in heart-lung machines brought about the availability of feedback loops from these safety devices to automatically shut off roller pumps in the advent of detectable air in the pump circuit. Further developments with in-line sensing systems enabled the perfusionist to continuously monitor arterial and venous pH. PO2, PCO2, venous saturation, hemoglobin/hematocrit, and temperature. The need for the analysis of data Collected during CPB for scientific investigation and quality assurance led perfusionists to use computer databases to handle the volumes of necessary information and produce meaningful reports. 65"68 As computers evolved and became more practical for use within the operating room, data acquisition has also been adapted by more perfusionists, reducing or eliminating the task of manually recording information every 10 to 15 minutes The next step, that of computer semi-intelligence, interpreting the acquired data and relaying advice on running the bypass circuit back to the user has not met with much success. As early as 1984. Riley posed a fictional account of a microprocessorcontrolled, computer-assisted pump that incorporated all of the individual monitoring devices and sensors into a complete feedback system. 69 This system also included an artificial intelligence that learned from previous troubleshooting and communicated advice to the perfusionist who could accept or reject it. The article was republished in 1993, with a follow-up in which Riley asked why computer-assisted bypass had not achieved greater acceptance7°: "The answer is simple: The potential for computer-assisted CPB technology has not impressed open heart teams to the point that these professionals will encourage or drive manufacturers to produce such systems" Presently, all the transducers and in-line sensing monitors necessary to continuously measure and control CPB parameters are available. There are commercially available systems that incorporate integrated microprocessor controls, sophisticated monitoring, a centrally located touchscreen, universal communication ports, and the software required to generate perfusion records using run-time data generated by the heart-lung ma-

PERFUSION SAFETY

chine. Systems have been developed that use photosensors and pressure sensors located throughout the circuit in a feedback arrangement to regulate bypass according to changes in venous return. 7~ More recently, a computerized pump control system has been used on 15 children during cardiac operations that regulates the central venous pressure with control algorithms to maintain constant intravascular volume. 72 Why have more perfusion teams not embraced the idea of computer-assisted CPB? Such a system would reduce the massive load that is placed on the individual operating the bypass circuit by decreasing the complexity of CPB by allowing the computer system to perform the repetitive tasks of scanning the circuit. Part of the answer is the fear of automation. There is a natural apprehension that the computer may take over the role of the perfusionist. Gourlay 73 addressed this fear by comparing perfusion to aviation: computers are essentially performing as pilot aids and not as replacement technology. In general, aircraft still take off and land under manual control with the computer systems taking over the flight control function only during level steady flight conditions. This may also be the case in applying computers to perfusion practice. One can foresee that a patient would be put on and taken off bypass manually with computers taking control of the general running of the system during stable perfusion conditions. •

.

.

Another part of the problem, especially in the past, was the lack of computer knowledge. As the world becomes more computer literate and as computers and software make it easier to implement these new systems, the use and applications of computers in routine clinical perfusion practice will continue to grow. OTHER AREAS AFFECTING SAFE CARDIOPULMONARY BYPASS

Education, Certification, and Accreditation Another parameter that is specific for the human element of the CPB circuit is the education of the perfusionist. In recent years, the number of new perfusionists with advanced educational degrees has increased. There are even several Master's Degree in Perfusion programs being offered across the United States. Although this push for more education in the field of perfusion is good, it is not new to the field. As early as the late 1960s, there were efforts to raise the quality of those individuals practicing perfusion by the AmSECT. After several years' work, a national examination was administered in 1972 to define a perfusion knowledge database. With this database established, the examination was given for the first time on a pass/fail basis in 1974. The American Board of Cardiovascular Perfusion (ABCP) was established in 1975 to administer the examination. Patterned after the anesthesiology and thoracic surgery certification processes, the examination consisted of both a written and an oral part. In addition, the American Board required the annual recertification of perfusionists by the accumulation of points from clinical and professional activities. For several years, the American Board accredited training programs based on the establishment of minimum standards. Over the years, the accreditation of perfusion training programs has come under the auspices of several agencies from

387

the Council on Allied Health Education and Accreditation (CAHEA), the Joint Review Committee for Perfusion Education (JRC-PE), and the Council on Postsecondary Accreditation (COPA) to the Council on Recognition of Postsecondary Accreditation (CORPA), the Accreditation Committee for Perfusion Education (AC-PE), and the Commission on Accreditation of Allied Health Education Programs (CAAHEP). The original Essentials and Guidelines for an Accredited Educational Program for the Perfusionist was adopted by all of the major collaborating organizations in 1980 and was revised in 1984, 1989, and 1995. 74-77 These "essentials" outline the minimum requirements, and the "guidelines" give examples used in the development of perfusion training programs. The American Academy of Cardiovascular Perfusion (AACP) has published two statements in regards to perfusion education. "Education for Perfusionists, A Statement of Position by the American Academy of Cardiovascular Perfusion" was adopted in 1987. 78 It endorsed the formal training of perfusionists, and it asked for the rigid enforcement of existing regulations. It also asked the JRC-PE to adopt even more stringent regulations in regard to student clinical training and experience. In 1993, the AACP released another position statement reaffirming their concern for perfusion education. "Characteristics of an Effective Perfusion Education Program" listed a set of guidelines by which the ideal perfusion training program would be run. 79 The number of cases performed by students, the types of educational and clinical exposure, and even outcome analysis of graduates regarding performance in the ABCP ceItification examination were specified in the document. Similar efforts to set up formal training programs and certification have recently taken place in Europe. To unite perfusionists in their desire for equality of standards in both training and professional status, the European Board of Cardiovascular Perfusion (EBCP) was established in 1991. The European Board, founded by perfusionists representing 16 countries, is supported by the European Association of CardioThoracic Surgery, the European Society for Cardiovascular Surgery, and the European Association of Cardiothoracic Anesthesiologists. The first two objectives of the European Board are strikingly similar to those of their American counterparts: (1) Establish, monitor and maintain equality of standards in education and training. (2) Set out the Essentials and Guidelines by which training programs will be accredited by the board. Perfusion education, still seen by many as one of the most important issues in the profession, was openly discussed in a public forum at the Annual Seminar of the AACP in January 1995. 8o-87 For the first time in history, representatives from every major American perfusion organization were gathered together in a panel discussion format to discuss perfusion education and accreditation. Many issues were addressed, but all agreed that communication among the organizations involved was vitally important in maintaining quality perfusion education and training.

Standards Standards in perfusion can be divided into two types: those for devices and those for the personnel involved. Device standards, especially for oxygenators, have been proposed by several organizations since the early 1970s. The original work

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DAVID A. PALANZO

was performed by a subcommittee of the American Society for Artificial Internal Organs (ASAIO). After years of work, a second organization, the Association for the Advancement of Medical Instrumentation (AAMI), continued the effort to develop an oxygenator standard. In 1982, AAMI published a draft standard by which manufacturers could test and compare their devices to determine oxygen and carbon dioxide transfer rates, heat exchanger performances, and blood cell damage. 88 In 1990, the International Standards Organization (ISO) endorsed an oxygenator standard that was based on the earlier draft work of ASAIO and AAMI. 89 Taking into consideration that some of the test standards were not pertinent to clinical utilization of the devices, the ISO standard for oxygenators was revised in 1993. 9o The new revision no longer included animal survival studies as part of the proposed standard, as the earlier drafts did. Other changes involved the method in which the test results would be reported. The first published standard of practice in perfusion was released by the Standards of Practice committee of AmSECT in 1978. 91 This draft standard addressed the information that needed to be recorded during CPB. Despite the fact that many institutions used this published draft to create their own perfusion records, it was not endorsed by the membership. Many hospitals had protocols or at least guidelines in place in the 1970s, but it was not until the mid to late 1980s when proposed standards on the national level appeared. In 1987, the AACP published its "Standards of Practice, ''92 which was adopted by the active membership. The document included sections on record keeping, equipment, personnel, prebypass checklist, and perfusion management. Through the work of the Perfusion Quality Committee, AmSECT published a prebypass checklist in 1990. 93 This document provided a guideline to ensure that the perfusionist was prepared for CPB. The Perfusion Quality Committee also developed a "Perfusion Scope of Practice ''94 after soliciting job descriptions from its members. The scope of practice was published in 1991 and after review was endorsed by the AmSECT membership. The next step was to develop a standard of practice, so "Essentials for Perfusion Practice, Clinical Function: Conduct of Extracorporeal Circulation" was published and endorsed by the members of AmSECT in 1993.95 The Perfusion Quality Committee then conducted a national

mail survey to document perfusion practice so that guidelines for the previously adopted "Essentials" could be developed. The "Guidelines for Perfusion Practice" were approved by the AmSECT Board of Directors in October 1994 and presented to the membership for adoption in March 1995. 96 CONCLUSIONS

Many improvements have occurred over the past 45 years to make CPB safer. These changes have come from many areas, including circuit design, engineering and manufacturing of equipment, education and training of perfusionists, adoption of policies, protocols and standards, surgical techniques, and the conduct and management of perfusion. Even though the incidence of permanent injury or death resulting from a CPBrelated problem is extremely low, there is still room for improvement. The last accident survey was published over 10 years ago, and it is time for a new one. The information that is gathered and analyzed from such a survey will allow analysis of progress and what needs to be changed. In general, the human body dislikes CPB. The entire bypass circuit is seen as foreign, and the body reacts in such a manner to combat against its invasion. In the years ahead, further advances in biocompatibility, membrane oxygenator physiology, and a resurgence of pulsatile perfusion will allow CPB to come closer to mimicking human anatomy and physiology. Along with these improvements will have to come the same meticulous attention to safety that has accompanied technological advancements in the past. How long will all of this take? Much depends on the nature of health care in the future. With the ever-increasing cost restraints, money for research and development will continue to decrease. Will safer, computer-controlled systems be too expensive to use for routine CPB? With all the possible changes and advancements in technology, the last line of defense in patient safety during CPB is the perfusionist. The perfusionist needs to stay current in the knowledge and technology of perfusion management. It is also the perfusionist's responsibility to be an active participant in research and in the clinical decisions that can affect the safety of CPB. ACKNOWLEDGMENT

The author thanks Thomas F. Ebersole, CCP, for his extensive search of the PerfSearch database.

REFERENCES

1. Galletti PM, Brecher GA: Heart-Lung Bypass: Principles and Techniques of Extracorporeal Circulation. New York, NY, Grune and Stratton, 1962, pp 84-87, 104-105 2. Galleni PM, Brecher GA: Heart-Lung Bypass: Principles and Techniques of Extracorporeal Circulation. New York, NY, Grune and Stratton, 1962, pp 74-75 3. Senning A: Ventricular fibrillation during extracorporeal circulation used as a method to prevent air embolism and to facilitate intracardiac operations. Acata Chir Scand Suppl 171:1-79, 1952 4. Glenn WWL, Sewell WH: Experimental cardiac surgery. IV. The prevention of air embolism in open heart surgery: Repair of interatrial septal defects. Surgery 34:195-206, 1953 5. Nixon PG: A simple flowmeter and safety device for the extracorporeal circulation. J Thorac Cardiovasc Surg 2:830, 1959

6. Olmsted F, Kolff WJ, Effier DB: Three safety devices for the heart-lung machine. Cleve Clin Q 25:169-176, 1958 7. Zaroff LI, K,reel I, Kavee DJ, et al: Mechanical failure during extracorporeal circulation: A method for prevention. Surgery 45:645647, 1959 8. Jones RD, Cross FS: A vent valve to minimize air embolism during open-heart surgery. J Thorac Cardiovasc Surg 48:310, 1964 9. Brenner WI, Wallsh E, Spencer FC: Efficiency of aortic vents in the prevention of air embolism. Surg Forum 21:139-142, 1970 10. Burgess FM: Retrograde dissection during cardiopulmonary bypass. J Extra-Corpor Technol 6:86-90, 1974 11. Irmiter RJ, Waldon AJ III: A method of removing Halothane vapors from clinical oxygenators using an activated charcoal canister. AmSECT Proc 5:58-62, 1977

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12. Kurusz M, Shaffer CW, Christman EW, et al: Runaway pump head: New cause of gas embolism during cardiopulmonary bypass. J Thorac Cardiovasc Surg 77:792-795, 1979 13. Stoney WS, Alford WC Jr, Burrus GR, et al: Air embolism and other accidents using pump oxygenators. Ann Thorac Surg 29:336-340, 1980 14. Mills NL, Ochsner JL: Massive air embolism during cardiopulmonary bypass: Causes, prevention and management. J Thorac Cardiovasc Surg 80:708-717, 1980 15. Underwood S, Widmer S, Butler B, et al: Power failure and the pump: How effective is manual operation? J Extra-Corpor Technol 19:365-368, 1987 16. Hargrove M, O'Brien D, Aherne T: Failure of electrical mains and backup generator supply during cardiopulmonary bypass. J ExtraCorpor Techno121:28-29, 1989 17. Long GW, Fleenor JT: Evaluation of an emergency drive system for a disabled arterial pump head. J Extra-Corpor Technol 14:337-340, 1982 18. Mortensen JD, Yates WG, Schoenberg AA, et al: Final report: Cardiopulmonary bypass systems: A study of safety and performance. TR 5534-010, Contract 223-80-5081, Salt Lake City, UT, University of Utah Research Institute, April 1981 19. Mortensen JD: Potential methods for controlling risks and hazards of CPB devices. Proc Am Acad Cardiovasc Perfusion 2:57-68, 1981 20. Stofer RC: The hidden hazards of perfusion. Proc Am Acad Cardiovasc Perfusion 3:46-48, 1982 21. Schabel RK, Berryessa RG, Justison GA, et al: Ten common perfusion problems: Prevention and treatment protocols. J Extra-Corpor Technol 19:392-398, 1987 22. Boothman BR: Dangers of cardiopulmonary bypass operations. Br Med J 298:254-255, 1989 23. Wheeldon DR: Can cardiopulmonary bypass be a safe procedure?, in Longmore DB (ed): Towards Safer Cardiac Surgery. Lancaster, UK, MTP Ltd, 1981, pp 427-446 24. Wheeldon DR: Safety during cardiopulmonary bypass, in: Proceedings of the First World Congress on Open-Heart Technology. London, UK, Franklin Scientific Projects Ltd, 1982, pp 27-29 25. Kurusz M, Conti VR, Arens JF, et al: Perfusion accident survey. Proc Am Acad Cardiovasc Perfusion 7:57-65, 1986 26. Berkowitz DE: Inspection and preventive maintenance of cardiopulmonary perfnsion equipment and an overview of problems. J Extra-Corpor Technol 12:68-70, 1980 27. Kurusz M, Crane TN, Speer D: Preventive maintenance of heart-lung machines. Proc Am Acad Cardiovasc Perfusion 6:34-37, 1985 28. Higgins M, Tyndal CM Jr, Berryessa RG, Hydrick DR: Is your oxygenator failing? Diagnosis and suggested treatment. J Extra-Corpor Technol 19:330-337, 1987 29. Frazier TM: The automatic level regulator as a low level safety device and voIume regulator. Proc Am Acad Cardiovasc Perfusion 5:73-75, 1984 30. Vinansky RR Hill AG, Groom RC, et al: Pressure measurement and safety with a self-contained device. Proc Am Acad Cardiovasc Perfusion 7:101-104, 1986 31. Snyder EJ, Weckerly S, Gross L, et al: A negative pressure alarm for use in neonatal extracorporeal membrane oxygenation. J ExtraCorpor Techno120:63-66, 1988 32. Christman EW, Kurusz M: Preventing massive gas embolism during cardiopulmonary bypass: A review of safety devices. J ExtraCorpor Technol 12:115-119, 1980 33. Hill AG, Lefrak EA: Cardiopulmonary bypass safety devices and techniques. Proc Am Acad Cardiovasc Perfusion 6:38-42, 1985

389

34. Kriewall TJ: Safety systems in perfusion: Practices, philosophy and products. Perfusion Life 11:18-23, 1994 35. Kumsz M, Faulkner SC: Followup comments from the 1985 perfusion accident survey. Proc Am Acad Cardiovasc Perfusion 8:210212, 1987 36. Fransen R: The courts and perfusiou accidents. Proc Am Acad Cardiovasc Perfusion 8:213-216, 1987 37. Friday PJ: The psychological results of perfusion accidents. Proc Am Acad Cardiovasc Perfusion 8:217-219, 1987 38. Reed CC: Perfusion accidents and the expert witness. Proc Am Acad Cardiovasc Perfusion 8:220-223, 1987 39. Kurusz M, Fransen R, Reed CC, Friday PJ: Perfusion accidents and the results: Panel discussion. Proc Am Acad Cardiovasc Perfusion 8:224-227, 1987 40. Warburton R: Prevention: Better than cure. Perfusion 3:79-82, 1988 41. Hunt P: Safety in aviation. Perfusion 3:83-96, 1988 42. Kurusz M, Wheeldon DR: Perfusion safety. Perfusion 3:97-112, 1988 43. Pearson DT: Blood gas control during cardiopulmonary bypass. Perfusion 3:113-133, 1988 44. Marshall L: Filtration in cardiopulmonary bypass: Past, present and future. Perfusion 3:135-147, 1988 45. Kurusz M, Wheeldon DR: Risk containment during cardiopulmonary bypass. Semin Thorac Cardiovasc Surg 2:400-409, 1990 46. Eagle CJ, Davies JM, McCloskey B: An introduction to quality assurance with an application for perfusionists. J Extra-Corpor Technol 23:22-25, 1991 47. Courtney PH Jr, Qi Han Y, Warren ET, Heath BJ: Gross air handling characteristics of membrane oxygenators: An in vitro study. J Extra-Corpor Techno126:6-12, 1994 48. Southworth R, Riley JB: Comparison of one-way arterial line valves for centrifugal pumping during cardiopulmonary bypass. Proc Am Acad Cardiovasc Perfusion 15:103-107, 1994 49. Springer MA, Korth DC, Guiterrez PJ, et al: An in vitro analysis of a one-way arterial check valve. J Extra-Corpor Technol 27:29-33, 1995 50. Morimura K: Case of massive air embolism during cardiopulmonary bypass. Nippon Kyobu Geka Gakkai Zasshi 43:1062, 1995 51. Ionescu MI: Techniques in Extracorporeal Circulation (ed 2). London, England, Butterworths, 1981 52. Reed CC, Clark DK: Cardiopulmonary Peffusion. Houston, TX, Texas Medical Press, 1975 53. Reed CC, Stafford TB: Cardiopulmonary Bypass. Houston, TX, Texas Medical Press, 1985 54. Taylor KM (ed): Cardiopulmonary Bypass: Principles and Management. Baltimore, MD, Williams & Wilkins, 1986 55. Reed CC, Kurusz, M, Lawrence AE Jr: Safety and Techniques in Perfusion. Stafford, TX, Quali-Med, 1988 56. Gravlee GP, Davis RF, Utley JR (eds): Cardiopulmonary Bypass: Principles and Practice. Baltimore, MD, Williams & Wilkins, 1993 57. Miller DW Jr, Binford JM, Hessel EA III: Results of a survey of the professional activities of 811 cardiopulmonary perfusionists. J Thorac Cardiovasc Surg 83:385-389, 1982 58. Kurusz M, Schneider B, Brown JR Conti VR: Filtration during open-heart surgery: Devices, techniques, opinions and complications. Proc Am Acad Cardiovasc Perfusion 4:123-129, 1983 59. American Society of Extra-Corporeal Technology: Perfusion practice survey. Perfusion Life 11:42-45, 1994 60. Cardiothoracic Research & Education Foundation: San Diego Cardiopulmonary Bypass Symposium 1995 Survey. Pathophysiology & Techniques of Cardiopulmonary Bypass XVI, February 29-March 2, 1996 61. Kolff J, Ankney RN, Wurzel D, Devineni R: Centrifugal pump

390

failures. Pathophysiology & Techniques of Cardiopulmonary Bypass XVI, 1996 (abstr) 62. Bjork VO: Safety factors in open-heart surgery. J Thorac Cardiovasc Surg 54:161-181, 1967 63. Melrose DG, Aird I: A mechanical heart-lung for use in man. Br Med J 2:57-62, 1953 64. Gibbon JH Jr: Artificial maintenance of circulation during experimental occlusion of pulmonary artery. Arch Surg 34:1105-1131, 1937 65. Palanzo DA, Wolf PD, Francalancia NA, et al: A data management system for perfusion technology. Proc Am Acad Cardiovasc Perfusion 4:20-23, 1983 66. Hayes RS: Computerized data acquisition an data management for the open heart patient. J Extra-Corpor Technol 19:23-27, 1987 67. Wilt LS, Silveshein JL: Applications of a laptop microcomputer during cardiopulmonary bypass. Proceedings from the 26th International Conference of the American Society of Extra-Corporeal Technology, Anaheim, CA, March 1t-14, 1988, pp 32-37 68. Jerabek CF, Walton HG, Sngden EH: An inexpensive real-time computer system for cardiac surgery. Proceedings from the 26th International Conference of the American Society of Extra-Corporeal Technology, Anaheim, CA, March 11-14, 1988, pp 23-27 69. Riley JB: McCab. Perfusion Life 1:4-5, 1984 70. Riley JB: What computers have not done for us, and why. Perfusion Life 10:17, 1993 71. Ade WR, Hino T, Kaizuka H, Wada J: Autoregulated extra- and intracorporeal pump system for perfusion. Int Surg 77:108-110, 1992 72. Beppu T, Imai Y, Fukui Y: A computerized control system for cardiopulmonary bypass. J Thorac Cardiovasc Surg 109:428-438, 1995 73. Gourlay T: Computers in perfusiou practice. Perfusion 2:79-85, 1987 74. Joint Review Committee for Perfusion Education (JRC-PE): Essentials and guidelines for an accredited educational program for the perfusionist. Chicago, IL, JRC-PE, 1980 75. Joint Review Committee for Perfusion Education (JRC-PE): Essentials and guidelines for an accredited educational program for the perfusionist. Chicago, IL, JRC-PE, 1984 76. Joint Review Committee for Perfusion Education (JRC-PE): Essentials and guidelines for an accredited educational program for the perfusionist. Chicago, IL, JRC-PE, 1989 77. Accreditation Committee for Perfusion Education (AC-PE): Essentials and guidelines for an accredited educational program for the perfusionist. Chicago, IL, AC-PE, 1995 78. American Academy of Cardiovascular Perfusion: Education for perfusionists; a statement of position by the American Academy of Cardiovascular Perfusion. Proc Am Acad Cardiovasc Perfusion 8:271, 1987 79. AmericanAcademy of Cardiovascular Perfusion: Characteristics

DAVID A. PALANZO

of an effective perfusion education program. Proc Am Acad Cardiovasc Perfusion 14:193, 1993 80. Sanford DM: Perfusion education and program accreditation. Proc Am Acad Cardiovasc Perfusion 16:11-13, 1995 81. Clark D: Issues in perfusion accreditation. Proc Am Acad Cardiovasc Perfusion 16:14-17, 1995 82. Horgan W: Perfusion accreditation. Proc Am Acad Cardiovasc Perfusion 16:18-21, 1995 83. Riley JB: The professionalism of perfusionists from the point of view of a member of the American Society of Extra-Corporeal Technology (AmSECT). Proc Am Acad Cardiovasc Perfusion 16:22-25, 1995 84. Pfefferkorn S: ABCP opening remarks. Proc Am Acad Cardiovasc Perfusion 16:26-27, 1995 85. Richmond B: A historical perspective of the role of the American Board of Cardiovascular Perfusion in the accreditation process. Proc Am Acad Cardiovasc Perfusion 16:28-33, 1995 86. Lange JS: Perfusion Program Director's Council: Goals and philosophy. Proc Am Acad Cardiovasc Perfusion 16:34-36, 1995 87. Sanford DM, Clark D, Horgan WJ, et al: Panel discussion: Perfusion education and program accreditation. Proc Am Acad Cardiovasc Perfusion 16:37-48, 1995 88. Association for the Advancement of Medical Instrumentation: Standard for blood/gas exchange devices-oxygenators (draft). AAMI Oxy-D (2/80) R., Arlington, VA, February 1982 revision 89. Association for the Advancement of Medical Instrumentation: ISO/CD: Cardiovascular implants and artificial organs: Blood-gas exchangers (oxygenators). AAMI-ISO 7199.2. Arlington, VA, Revision 1990 90. Association for the Advancement of Medical Instrumentation: ISO/CD: Cardiovascular implants and artificial organs: Blood-gas exchangers (oxygenators). AAMI-ISO 7199.2. Arlington, VA, Revision 1993 91. American Society of Extra-Corporeal Technology: Standards of practice: Recommended minimum standards, permanent perfusion records. J Extra-Corpor Technol 10:46, 1978 92. American Academy of Cardiovascular Perfusion: Standards of practice: A statement of the American Academy of Cardiovascular Perfusion. Proc Am Acad Cardiovasc Perfnsion 8:272-274, 1987 93. American Society of Extra-Corporeal Technology: Pre-bypass perfusion safety checklist. Perfusion Life 7:76-77, 1990 94. American Society of Extra-Corporeal Technology: Perfusion scope of practice. Perfusion Life 8:7, 1991 95. American Society of Extra-Corporeal Technology: Members accept essentials, approve revised code of ethics. Perfusion Life 10:14, 1993 96. American Society of Extra-Corporeal Technology: Guidelines for Perfusion Practice. Perfusion Life 12:20-22, 1995