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Bubbles in the bloodstream are not a normal condition -yet they remain a fact of cardiopulmonary bypass (CPB), having been extensively studied and documented since its inception some 50 years ago. While detectable levels of gaseous microemboli (GME) have decreased significantly in recent years and gross air embolism has been nearly eliminated due to increased awareness of etiologies and technological advances, methods of use of current perfusion systems continue to elicit concerns over how best to totally eliminate GME during open-heart procedures. A few studies have correlated adverse neurocognitive manifestations associated with excessive quantities of GME.Newer techniques currently in vogue, such as vacuum-assisted venous drainage, low-prime perfusion circuits, and carbon dioxide flooding of the operative field, have, in some instances, exacerbated the problem of gas embolism or engendered secondary complications in the safe conduct of CPB. Doppler monitoring (circuit or transcranial) primarily remains a research tool to detect GME emanating from the circuit or passing into the patients’ cerebral vasculature. Newer developments not yet widely available, such as multiple-frequency harmonics, may finally provide a tool to distinguish particulate microemboli from GME and further delineate the clinical significance of GME.

Percutaneous cardiopulmonary support systems (PCPS) are compact, battery-powered, portable heart-lung machines that can be implemented rapidly in any area of the hospital using thin-walled cannulae inserted via the femoral vessels. PCPS provides temporary circulatory support by actively aspirating blood from the patient’s venous system using a centrifugal pump and hollow fiber membrane oxygenator for gas exchange. A review of clinical reports has delineated several indications for emergent applications, with the most frequent being cardiac arrest (CA) or cardiogenic shock (CS). Survival is more likely in patients with CS (40%) compared to CA (21%). Implementation of PCPS after unwitnessed CA or cardiopulmonary resuscitation > 30 min yields a patient survival rate of < 10%. The likelihood of patient survival after emergent PCPS is most often related to the patient undergoing a definitive anatomic surgical repair such as coronary artery bypass or pulmonary embolectomy. If the need for circulatory support extends beyond 6 h, conversion to conventional long-term extracorporeal membrane oxygenation or a ventricular assist device is recommended.

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.

While the techniques and equipment used 50 years ago may seem primitive by today's standards, they did permit cardiac surgery to rapidly develop. As early as 1951, Karlson would write: 'Recent advances in surgery have made operations upon the heart much more than surgical stunts, and have opened a hitherto relatively untouched field of surgical endeavor. A few years later, Mustard would defend his abysmal series of repairs of congenital cardiac defects by saying, 'Our techniques of perfusion and operation have proved feasible in three human cases, but the results are not adequate to operate freely on good-risk patients at the present time. It is hoped that improvements in techniques will soon make this possible'. By the end of the decade of the 1950s. Gross would express the following: In the support of human patients on pump oxygenators, the intricacies of technic are many, and the extent of problems is broad, but much clarity of thought is now evident. We can set forth certain statements considered to represent truths or valuable viewpoints, since in most cases they have derived from scores of laboratory experiences during which some 800 dogs have been used by us, or else they have been crystallized from bitter experience at the operating table, or shattering disappointments in postoperative failures. Fortunately, many of the conclusions have sprung from happy and rewarding results exhibited by patients who have weathered corrective surgery in a very satisfactory manner. In closing, after reviewing the early perfusion literature, it is evident that many techniques used in the 1930s, 1940s, and 1950s persist to the present. Some techniques fell out of favor, such as elective hyperkalemic arrest, only to be re-established decades later. Simplicity is the hallmark of the most enduring techniques, a thought expressed by Lillehei in 1955. Somewhat amazingly, full automation of the extracorporeal circuit existed on some of the very early machines, but perhaps because of the explosive growth of cardiac surgery and the need for disposable circuits that could be rapidly assembled, the safety aspects of heart-lung machines were neglected for many decades. Some would argue it still has not realized its potential for elimination of error in the conduct of cardiopulmonary bypass. However, cardiac surgery would not wait, and in 1956, Osborn would boldly state: 'Extracorporeal circulation for surgery of the heart has now come of age.