2021 MiECTiS focused update on the 2016 position paper for the use of minimal invasive extracorporeal circulation in cardiac surgery.

The landmark 2016 Minimal Invasive Extracorporeal Technologies International Society (MiECTiS) position paper promoted the creation of a common language between cardiac surgeons, anesthesiologists and perfusionists which led to the development of a stable framework that paved the way for the advancement of minimal invasive perfusion and related technologies. The current expert consensus document offers an update in areas for which new evidence has emerged. In the light of published literature, modular minimal invasive extracorporeal circulation (MiECC) has been established as a safe and effective perfusion technique that increases biocompatibility and ultimately ensures perfusion safety in all adult cardiac surgical procedures, including re-operations, aortic arch and emergency surgery. Moreover, it was recognized that incorporation of MiECC strategies advances minimal invasive cardiac surgery (MICS) by combining reduced surgical trauma with minimal physiologic derangements. Minimal Invasive Extracorporeal Technologies International Society considers MiECC as a physiologically-based multidisciplinary strategy for performing cardiac surgery that is associated with significant evidence-based clinical benefit that has accrued over the years. Widespread adoption of this technology is thus strongly advocated to obtain additional healthcare benefit while advancing patient care.

Comparison of a perfusion simulator to a clinical operating room: evaluation of eye tracking data and subjective perception. A pilot study.

BACKGROUND: With the aim of evaluating the perfusion simulator at the German Heart Center Berlin, similarity between simulation and clinical operation room (OR) was investigated regarding subjective perception and eye movement. METHODS: Eight perfusionists performed an operation on the heart-lung machine (HLM) wearing eye tracking glasses, each in real OR and simulator. The three most important phases for perfusionists (going on bypass, cardioplegia administration and coming off bypass) were considered. Additional to eye tracking data as objective measure, questionnaires were completed, and interviews conducted afterwards. RESULTS: The structure of simulator and real OR is perceived as basically the same. Yet there are differences in the HLM-models used and the temporal sequence. Different perception of both situations is reported in interviews and reflected in significant differences in the rating scales (NASA-TLX) on three of six subscales. In eye tracking data, certain AOIs could be identified for the individual phases, both in OR and simulator-an indication of fundamental similarity. However, differences regarding the proportions of the individual AOIs, especially in the first and third phase, are leading to the assumption that the simulator, and especially the simulation process, is only valid to a limited extent regarding subjective perception and eye tracking data. CONCLUSION: The use of the simulator for (advanced) training is accepted and explicitly requested by perfusionists. Yet further research is needed to identify the decisive factors (like simulation duration or additional tasks) for a valid execution in the simulator. Furthermore, a larger sample size should be regarded to allow statistical analysis.

Technical implementation of percutaneous thrombus aspiration using the AngioVac system.

OBJECTIVES: The AngioVac system (AngioDynamics, Latham, NY, USA) provides a method for the minimally invasive, percutaneous aspiration of thrombus formations originating from the central venous system as well as solid matter such as lead vegetations and right atrial thrombi. METHODS: This retrospective, observational study describes the initial experience in 52 adult patients with the AngioVac system, focusing mainly on the development of the extracorporeal circuit to improve usability and safety. RESULTS: The mean patient age was 62.9 years (range 23-86 years). 22 patients were female and 30 were male. Indications for percutaneous aspiration were lead vegetations (n = 36; 69.2%), right atrial thrombi (n = 9; 17.3%), central venous thrombi (n = 5; 9.6%) and pulmonary embolisms (n = 2; 3.8%). Successful aspiration was performed in 44 cases (84.6%) and partial success was achieved in five patients (9.6%), while failure to remove thrombi or vegetations occurred in three cases (5.8%). Our practical experience led to the installation of a shunt line for recirculation and the implementation of safety features concerning air handling, which are also employed in minimally invasive extracorporeal bypass circuits. Initial tests monitored the level of negative pressure according to differences in flow and access sites but these still have to be validated on a larger scale. CONCLUSION: In this initial experience, the AngioVac system appeared to be safe regarding the extracorporeal circulation and the elimination of thrombi and lead vegetations.

Simulation-based training of critical events during cardiopulmonary bypass: importance of a critical events checklist.

OBJECTIVES: Evaluation of critical events training for clinical perfusionists is necessary to improve this educational approach. Critical events checklists are effective in reducing clinical complications, but should be tested in a simulation environment first. Individual behavior and stress response of clinical perfusionists during simulated critical events on cardiopulmonary bypass have not been evaluated yet. This study focuses on the evaluation of critical events training and critical events checklists in simulated cardiopulmonary bypass. METHODS: A total of 19 clinical perfusionists from a single hospital took part in two simulated critical event scenarios. Clinical perfusionist behavior and physiological responses were recorded using eye tracking, heart rate variability, video, and audio. In addition, workloads were determined and participants were interviewed. RESULTS: Relevant areas of interest were identified for each simulation phase. During critical event detection and subsequent decision-making, areas of interest hits and fixation durations varied with the use of a critical events checklist. Times to decision were shorter, decision quality was higher, and temporal workload was increased when the checklist was used. Evaluation of selected heart rate variability measures revealed a good correlation with pupil diameters. CONCLUSION: Evaluation of critical events during simulated cardiopulmonary bypass shows that the scenario is realistic and relevant for clinical practice. Integrating a critical events checklist improves the probability of correct decision-making and shortens the correct decision time. Temporal workload is increased when using a checklist. Eye tracking and heart rate variability are well suited to evaluate participants' behaviors and stress levels. All participants welcomed simulation training for critical incidents.

Simulation in perfusion: evaluating the efficacy of a specific training with eye-tracking.

BACKGROUND: With the aim of integrating simulation training into the training of perfusionists, we examined whether the participants were able to transfer a specific learning content to the same and different situations and assessed their feedback on the simulation training. Eye-tracking was tested as a measure and supplemented by additional measures. METHODS: A 2 × 2 mixed design was used, with test time (pre- and post-test) and training group (same and different content training) as factors. In the pre- and post-test, the participant had to handle a critical situation on the cardiopulmonary bypass, namely, a drop in arterial partial oxygen pressure. Between the two test times, the participant practised under guidance the handling of either the same critical situation (Group 1) or a different one, that is, impaired venous return (Group 2). Dependent measures were fixations of the eyes on specific areas of interest on the heart-lung machine, measures of latency and subjective assessments. Moreover, participants gave feedback on the simulation training. RESULTS: Fixation analyses showed that the training led to an increased gaze on areas of interest relevant to the drop in arterial partial oxygen pressure in both groups, with a significant increase only for Group 1. The surveys revealed a great interest in the integration of simulation training into education. CONCLUSION: In combination with other measures, eye-tracking is suitable for the evaluation of simulation training. Due to the positive training effects and positive participant feedback, the integration of simulation into the training of perfusionists is advocated. Concerning transfer of learning content, more research is needed.

Evaluation of attention, perception, and stress levels of clinical cardiovascular perfusionists during cardiac operations: a pilot study.

BACKGROUND: Performing cardiopulmonary bypass is a complex task which involves evaluating visual input from patient monitors and technical parameters displayed at the heart-lung machine console as well as reacting to other sensory input. Only few studies are available concerning the competency requirements for clinical cardiovascular perfusionists, including attention, perception, and coping with mental stress. This study aims at evaluating attention, perception, and stress levels of clinical cardiovascular perfusionists during cardiopulmonary bypass. METHODS: Nine clinical cardiovascular perfusionists voluntarily offered to participate in the study. Participants were asked to wear Tobii 2 eye-tracking glasses throughout the procedures. Specific time points were analyzed (cardiopulmonary bypass on, initial cardioplegia delivery, steady state, cross-clamp off, and weaning from cardiopulmonary bypass). Data acquisition was supplemented by participants' self-evaluation regarding their stress levels and by National Aeronautics and Space Administration Task Load Index (NASA TLX) questionnaires. RESULTS: Seven datasets were sufficient to be evaluated. The clinical cardiovascular perfusionists' professional experience ranged from 0.5 to 24 years. Evaluation of eye-tracking data revealed large variations in areas of interest hits, fixation, and dwell times. Across all phases, the venous reservoir, mean arterial pressure, arterial pump display, cardioplegia control, and data management system received the highest levels of attention. Pupil diameter measurements increased at start of cardiopulmonary bypass, cardioplegia delivery, and weaning off, but returned to base level during steady state. Clinical cardiovascular perfusionists' self-evaluation showed that subjective stress level was highest at the start and the end of the procedure. NASA TLX questionnaires revealed medium-to-high mental and temporal workloads, but low physical workloads. Performance, effort, and frustration indices showed medium workloads. CONCLUSION: During cardiopulmonary bypass, perfusionists are subjected to stress. Peak stress levels were highest during start and end of cardiopulmonary bypass. Furthermore, visual attention and perception varied between the operative phases. Further studies are indicated to evaluate the design of heart-lung machines and stress-coping strategies during cardiopulmonary bypass.

Transfusion-free cardiopulmonary bypass in Jehovah's Witness patients weighing less than 5 kg.

Performing cardiac surgery on pediatric Jehovah's Witness patients is a great challenge for the surgical team and especially for the perfusionist. Jehovah's Witnesses reject blood transfusions on the grounds of their literal interpretation of passages of the Bible. In accordance with this belief, Jehovah's Witnesses feel that it is also forbidden to retransfuse autologous blood that has been separated from their own circulatory system. We report the use of cardiopulmonary bypass (CPB) during open-heart surgery in three infants with a body weight of 4.5 kg, 3.5 kg, and 3.1 kg, respectively, without transfusion of blood components. A small-volume CPB circuit with a priming volume of 200 mL, including the arterial line filter, was designed to decrease the degree of hemodilution. A dedicated pediatric heart lung machine console with remote pump heads and intensive blood conservation efforts allowed the operation without the use of donor blood. The CPB circuits were primed with crystalloid solution only. The procedures were performed in normothermia or in moderate hypothermia. Pre-CPB hemoglobin levels were 10.8 g/dL, 10.6 g/dL, and 8.5 g/dL. The hemoglobin concentrations measured during CPB ranged from 5.9 to 6.5 g/dL, 6.4 to 6.8 g/dL, and 5.5 to 5.9 g/dL, respectively. The patients did not receive any blood or blood products during their entire hospital stay.

Consumption of blood products during mechanical circulatory support in children: comparison between ECMO and a pulsatile ventricular assist device.

OBJECTIVE: Different mechanical circulatory support (MCS) systems are used in children with intractable heart failure. However, the need for anticoagulation leads to hemorrhage with subsequent use of blood products. We compared the coagulation disorders and the need for blood products in children treated either with extracorporeal membrane oxygenation (ECMO) or with the Berlin Heart pulsatile pneumatic ventricular assist device. PATIENTS: We retrospectively reviewed the first 8-day course of 64 children who were on MCS for more than 2 days between 1990 and 2002. Thirty children (median age 7.4 years, weight 25.5 kg) received Berlin Heart support and 34 children (median age 1.8 years, weight 9.2 kg) ECMO. Anticoagulation was accomplished by continuous infusion of heparin. Red blood cell count, platelet count, aPTT, AT III, fibrinogen, and ACT were measured regularly. Depending on blood loss and the coagulation disorder, red blood cells, fresh frozen plasma, platelets, and AT III were substituted. RESULTS: There were no preoperative differences in hematological parameters between the two groups. In the Berlin Heart group platelet transfusion was 4.3 ml x kg x day vs 24.6 ml x kg x day in the ECMO group. Red blood cell substitution was 17.2 vs 60.3 ml.kg.day. Fresh frozen plasma substitution was 8.5 ml x kg x day vs 46.9 ml x kg x day (P<0.001). Even in the congenital heart defect subgroups, when MCS was implanted without recent cardiotomy, the differences were significant. Nevertheless, the mean daily values for hemoglobin, platelets, and fibrinogen were lower in the ECMO group. There was lower overall mortality in the Berlin Heart group. CONCLUSIONS: Compared to ECMO, use of the Berlin Heart in children results in less blood loss and lower consumption of red blood cells, platelets, and fresh frozen plasma.

Transcontinental transport of a patient with an AbioMed BVS 5000 BVAD.

In patients with severe cardiogenic shock requiring implantation of a short-term assist device transportation to a specialized heart center for further therapy may be necessary. We report the first successful transcontinental air transport (from Singapore to Berlin, Germany) of a patient with fulminating myocarditis requiring implantation of a biventricular assist device.

Pulsatile mechanical cardiac assistance in pediatric patients with the Berlin heart ventricular assist device.

Mechanical cardiac assistance for neonates, infants, children and adolescents may be accomplished with pulsatile ventricular assist devices (VAD) instead of extracorporeal membrane oxygenation or centrifugal pumps. The Berlin Heart VAD consists of extracorporeal, pneumatically driven blood pumps for pulsatile univentricular or biventricular assistance for patients of all age groups. The blood pumps are heparin-coated. The stationary driving unit (IKUS) has the required enhanced compressor performance for pediatric pump sizes. The Berlin Heart VAD was used in a total number of 424 patients from 1987 to November 2001 at our institution. In 45 pediatric patients aged 2 days-17 years the Berlin Heart VAD was applied for long-term support (1-111 days, mean 20 days). There were three patient groups: Group I: "Bridge to transplantation" with various forms of cardiomyopathy (N = 21) or chronic stages of congenital heart disease (N = 9); Group II: "Rescue" in intractable heart failure after corrective surgery for congenital disease (N = 7) or in early graft failure after heart transplantation (N = 1); and Group III: "Acute myocarditis" (N = 7) as either bridge to transplantation or bridge to recovery. Seventeen patients were transplanted after support periods of between 4 and 111 days with 12 long-term survivors, having now survived for up to 10 years. Five patients (Groups I and III) were weaned from the system with four long-term survivors. In Group II only one patient survived after successful transplantation. Prolonged circulatory support with the Berlin Heart VAD is an effective method for bridging until cardiac recovery or transplantation in the pediatric age group. Extubation, mobilization, and enteral nutrition are possible. For long-term use, the Berlin Heart VAD offers advantages over centrifugal pumps and ECMO in respect to patient mobility and safety.

History of extracorporeal circulation: the conceptional and developmental period.

The development of modern techniques in extracorporeal circulation is the result of the combined efforts of physiologists, physicians, and engineers. Early experimental work at the end of the 19th century was accomplished by physiologists, such as von Schröder, von Frey, and Gruber, as well as Jacobj. These scientists laid the foundation for three different artificial oxygenation devices for experimental isolated animal organ perfusion. The developed bubble, film, and isolated lung oxygenation methods developed were later used for the first clinical cardiopulmonary bypass procedures in humans. For continuous perfusion experiments, closed circulation circuits were put into use. In a second step, during the first half of the 20th century, scientists and physicians, such as Brukhonenko, Gibbon, Crafoord, Björk, and Jongbloed were working on the refinement of these methods for intended application during cardiovascular operations in humans. Refined bubble and film oxygenators together with the modern blood pumps in closed circulatory systems were assembled as pump oxygenators, later called heart-lung machines. They were used in the first clinical cases of extracorporeal circulation for heart surgery in the second half of the 20th century by Dennis, Dogliotti and Constantini, and Gibbon.

History of extracorporeal circulation: the invention and modification of blood pumps.

The first roller pump was patented in 1855 by Porter and Bradley and was hand operated. A modification first named "surgical pump", designed and manufactured by E. E. Allen in 1887, was intended for direct blood transfusion. Truax, who also distributed and promoted the Allen pump with one roller, developed the first double roller pump in 1899. In the following decades, several researchers, including Beck, Van Allen, Bayliss and Müller as well as Henry and Jouvelet, refined the apparatus and recommended the use of roller pumps for blood transfusion and other applications. After further modifications made by DeBakey in 1934, and application of this pump in one of the first heart-lung machines constructed by Gibbon, DeBakey's name became inseparably attached to this type of pump. For perfusion experiments, an electrically powered roller pump was first used by Fleisch in 1935. Today, the roller pump is the most frequently used blood pump for cardiopulmonary bypass worldwide, having prevailed against the early pulsatile tube compression pumps and ventricular pumps. In recent years, centrifugal pumps have increasingly competed with roller pumps as systemic blood pumps for cardiopulmonary bypass and have become the preferred arterial pump in a variety of centers. Application of mechanical cardiac assistance has evolved from nonpulsatile roller pump support, followed by an era of pulsatile ventricular pumps to the rediscovery of the nonpulsatile flow mode with modern axial flow pumps.

Reduction of microemboli count in the priming fluid of cardiopulmonary bypass circuits.

Microemboli may impair cognitive function in patients undergoing heart surgery. Prebypass filtration has been shown to reduce particle load in the cardiopulmonary bypass (CPB) priming fluid. This study was performed to detect the embolic load of CPB priming fluid, to determine the efficacy of a 0.2 microm prebypass filter (PBF) in reducing emboli in the range of 0.1-5 microm and to provide guidelines for the handling of the device. A total of 12 CPB circuits were tested in two groups, using a laser light scattering particle counter, sensitive to microemboli in the range of 0.1-5 microm. In control group A, priming fluid before administration to the CPB circuit was analyzed. Group B circuits contained microporous membrane oxygenators (N = 5); group C consisted of CPB circuits with excluded membrane oxygenators (N = 7). When group A was compared to groups B and C, significantly more microemboli were found in the categories 0.2 microm, 0.5 microm, 0.8 microm for both groups B and C (p < .05). Group C circuits had higher microemboli counts in the categories 1.5 microm and 3 microm (p < .05) when compared to group B. Microemboli bigger than 0.2 microm could be eliminated after 2 min of prebypass filtration with a CPB flow of 5 L/min. The number of microemboli smaller than 0.2 microm was reduced substantially. Small microemboli with a size of 0.1 microm originate mainly from the priming solution. Microemboli in the range of 0.2 microm, 0.5 microm, and 0.8 microm originate mainly from the CBP circuit. In circuits with bypassed membrane oxygenators, a higher microemboli count in the range of 1.5 microm and 3 microm may be explained by a possible filtering capacity of membrane oxygenators. The 0.2 microm PBF is an effective tool to reduce the particle load in the CPB priming fluid.

Position article for the use of extracorporeal life support in adult patients.

Extracorporeal life support (ECLS) is one of the recent fields in cardiac surgery which has improved significantly the quality of patient care in acute or chronic end-stage heart disease. The safe use of this new technology requires many different prerequisites which are summarized in this position article. It includes the necessary personnel and their qualifications, the structural assumptions, the required equipment, and the parameters which have to be monitored for the safe usage of these devices. In addition, indications and contraindications for ECLS, the management and control of a wide range of parameters related to the extracorporeal circulation, as well as the necessary equipment are described. Quality assurance and education are also described in this position article.

Which competencies are necessary for clinical perfusion in Germany? Interviews with perfusionists.

BACKGROUND: The professional education of cardiovascular perfusionists in Germany and the expertise required for successful practice have not often been studied. Here, the necessary skills for clinical cardiovascular perfusion-ists are described. METHOD: The prerequisites for the practice of the profession, expected future developments and the question of the positioning of a future professional perfusionist training within the educational system were discussed with ten experienced perfusionists. These individuals were interviewed in a semi-standardized fashion following an interview manual and the interviews were evaluated using qualitative research methods. RESULTS: The professional skills currently required of per-fusionists correspond to the list of activities published by the German Society of Cardiovascular Enginering. New areas are knowledge of management and, increasingly, social competence and self-management skills. Future tasks for perfusionists will be more diversified than at present. CONCLUSION: Training for perfusionists should be made broader than it is today. The current restructuring taking place in the profession makes interdisciplinary orientation and increased emphasis on practical training necessary. Academic level education is both feasible and desirable.

Perfusion education and training in Europe.

Perfusion education and training varies considerably throughout Europe. Unlike in the US, where a common curriculum for perfusion education has been established, each European country has its own education system. This fact is further complicated by a multitude of national languages and cultures. Thus, perfusion education programmes vary, not only in content, but also in their academic levels. This article aims to give a comprehensive overview of the situation in each of the 20 member states of the European Board of Cardiovascular Perfusion (EBCP). The EBCP delegates were polled for a description of the process of training and education of clinical perfusionists in their respective countries. Following the initial delegate poll in 2001, an update of the material was performed in spring 2005. In summary, training of clinical perfusionists in Europe varies considerably between countries. A professional body is necessary to oversee the training process and to guarantee a minimum level of clinical competency for cardiovascular perfusionists.