Efficacy of the Pulse Pressure Generator during Cardiopulmonary Bypass Training Using the Extracorporeal Circulation Simulator

Objective: Cardiopulmonary bypass during cardiac surgery is an essential procedure, and the perfusionist needs to have sufficient education and training. Simulation training is suitable in such cases. We have developed a simulation system for cardiopulmonary bypass training (extracorporeal circulation simulator [ECCSIM]) and reported its efficacy. ECCSIM had no pulse pressure generator, so some perfusionists have mentioned that the operational feeling during training differs from that in real clinical cases. In this study, we have developed a new pulse pressure generator and examined the efficacy of this system during cardiopulmonary bypass training using ECCSIM. Materials and Methods: Results were observed as wave patterns during simulation of extracorporeal circulation with and without pulse pressure flow. Operational feeling during training of extracorporeal circulation was compared using a questionnaire survey, based on the Japanese version of the NASA Task Load Index (NASA-TLX), a subjective index, completed by seven perfusionists. Results: With the addition of pulse pressure flow, fluctuation of arterial flow at low speed with the centrifugal pump increased, and operation of extracorporeal circulation became unstable. The questionnaire survey, including ‘Operational feeling of centrifugal pump’, ‘Feeling of afterload’, and ‘Display of pressure monitor’, showed results similar to that of the clinical situation using pulse pressure flow. The difficulty of simulator operation in extracorporeal circulation was significantly greater in the group with pulse pressure flow. Mental/physical load examined with NASA-TLX increased with pulse pressure flow. Conclusion: Using a new pulse pressure generator with ECCSIM was effective in extracorporeal circulation training

Combination of Myogenic and Neurogenic Motor Evoked Potential Monitoring During Thoracoabdominal Aortic Surgery

A 64-year-old woman was evaluated for thoracoabdominal aortic aneurysms (TAAAs). Preoperative computed tomography showed a TAAA extending from the level of the diaphragm to the renal arteries. The Adamkiewicz artery (AKA) arose at the Th10 level, close to the aneurysm, and an abdominal aortic prosthesis and left iliac artery aneurysm were detected. Myogenic and neurogenic motor evoked potentials (MEPs) were monitored during the surgical repair of the TAAA, and there were differences between the two types of MEPs during surgery. Both MEPs fell below 50% of their baseline levels during surgery, which suggested critical ischemia, but the decrease in the myogenic MEP occurred at a different time from the decrease in the neurogenic MEP. A time-course analysis suggested that AKA reimplantation was unnecessary and all intercostal arteries were ligated. Both MEPs recovered completely by the end of surgery and there were no postoperative neurologic deficits. Our findings suggest that the combination of myogenic and neurogenic MEP monitoring is helpful in evaluating spinal cord injury during the surgical repair of TAAAs

Genome-Wide Association Study Confirming Association of HLA-DP with Protection against Chronic Hepatitis B and Viral Clearance in Japanese and Korean

Hepatitis B virus (HBV) infection can lead to serious liver diseases, including liver cirrhosis (LC) and hepatocellular carcinoma (HCC); however, about 85–90% of infected individuals become inactive carriers with sustained biochemical remission and very low risk of LC or HCC. To identify host genetic factors contributing to HBV clearance, we conducted genome-wide association studies (GWAS) and replication analysis using samples from HBV carriers and spontaneously HBV-resolved Japanese and Korean individuals. Association analysis in the Japanese and Korean data identified the HLA-DPA1 and HLA-DPB1 genes with Pmeta = 1.89×10−12 for rs3077 and Pmeta = 9.69×10−10 for rs9277542. We also found that the HLA-DPA1 and HLA-DPB1 genes were significantly associated with protective effects against chronic hepatitis B (CHB) in Japanese, Korean and other Asian populations, including Chinese and Thai individuals (Pmeta = 4.40×10−19 for rs3077 and Pmeta = 1.28×10−15 for rs9277542). These results suggest that the associations between the HLA-DP locus and the protective effects against persistent HBV infection and with clearance of HBV were replicated widely in East Asian populations; however, there are no reports of GWAS in Caucasian or African populations. Based on the GWAS in this study, there were no significant SNPs associated with HCC development. To clarify the pathogenesis of CHB and the mechanisms of HBV clearance, further studies are necessary, including functional analyses of the HLA-DP molecule

Anatomy-Specific Pancreatic Stump Management to Reduce the Risk of Pancreatic Fistula After Pancreatic Head Resection.

BACKGROUND: The anatomical status of the pancreatic remnant after a pancreatic head resection varies greatly among patients. The aim of the present study was to improve management of the pancreatic remnant for reducing pancreatic fistula after pancreatic head resection. METHODS: Ninety-five consecutive patients who underwent an end-to-side, duct-to-mucosa pancreaticojejunostomy after pancreatic head resection were included in the study. To approximate the pancreatic stump to the jejunum, the transfixing and interrupted suture techniques were used in 51 and 44 patients, respectively. We modified the interrupted suture technique according to the anatomical status of the pancreatic remnant, i.e., the shape of the pancreatic stump and the location of the pancreatic duct. RESULTS: There was no operative mortality in this study. Overall, 14 patients (15%) developed a clinically relevant pancreatic fistula. Certain anatomical features, including a small pancreatic duct, a soft, nonfibrotic pancreatic gland, and a pancreatic duct adjacent to the posterior cut edge, were significantly associated with pancreatic fistula. The fistula rate in the interrupted suture group was 7%, lower than that (22%) in the transfixing suture group (P = 0.036), and it was not influenced by pancreatic anatomy. Multivariate analysis identified a nonfibrotic pancreas (versus fibrotic pancreas; odds ratio [OR] 12.58, 95% CI 1.2-23.9; P = 0.001), a soft pancreas (versus hard pancreas; OR 4.67, CI 1.2-51.1; P = 0.006), and the transfixing suture technique (versus interrupted suture technique; OR 9.91, CI 1.7-57.5; P = 0.003) as significant predictors of clinically relevant pancreatic fistula. CONCLUSIONS: Pancreatic anastomosis modified according to the pancreatic anatomy is effective in reducing the risk of pancreatic fistula formation with end-to-side, duct-to-mucosa pancreaticojejunostomy after pancreatic head resection

Virtual Patient Simulator for the Perfusion Resource Management Drill

Perfusionists require a detailed understanding of a patient’s physiological status while comprehending the mechanics and engineering of the cardiopulmonary bypass system, so it is beneficial for them to obtain relevant practical skills using extra-corporeal circulation technology and educational physiological simulators. We designed a perfusion simulator system (ECCSIM: Extracorporeal Circulation SIMulator system) based on a hybrid of a simple hydraulic mock circulation loop linked to a computer simulation model. Patient physiological conditions (height, weight, and cardiac indices) were determined by a parameter estimation procedure and used to accurately reproduce hemodynamic conditions. Extracorporeal circulation trainees in pre-clinical education were able to maintain venous oxygen saturation levels above 50%, except during cardiac standstill and a brief resumption of pulsation. Infant amplitudes of reservoir volume oscillation and flow rate were greatly increased compared with adult cardiovascular parameters, this enabled the instructor to control the difficulty level of the operation using different hemodynamic variations. High-fidelity simula tor systems with controllable difficulty levels and high physiological reproducibility are useful in constructing a perfusion resource management environment that enable basic training and periodic crisis management drills to be performed

Evaluation of Basic Perfusion Techniques, ECCSIM-Lite Simulator

Although serious accidents during extracorporeal circulation are infrequent, potential adverse events with both equipment and operation do still occur and require immediate and well-coordinated responses. Hence, perfusionists need to be well trained in both standard and emergency procedures, and this would be aided by the establishment of an official education and training curriculum. In particular, the establishment of a simulator-based educational program and corresponding evaluation methods will spur development of increasingly medical simulators. Extra-Corporeal Circulation SIMulator (ECCSIM-Lite) was used during repeated sessions of undergraduate students (n = 12) using a simple training scenario. Trainees aimed to maintain reservoir volume around a constant mean, and increase or decrease the arterial flow avoiding rapid variations, and their performance was monitored. Ability to prevent backflow was also recorded as a measure of accomplishment. Skills in performances were evaluated by using a scoring system based on task accomplishment. Accomplishment score was improved in all participants after 1 week of training. Accomplishment scores reflecting ability to maintain flow improved to an average of 78%; in the third and final practice session backflow was prevented in 100% of cases. The average reservoir level maintenance score in the flow-up phase was 75%, in the flow-maintenance phase was 92%, and in the flow-down phase was 58%. During skill training, in which trainees learn methods of avoiding adverse events, the use of simulators combined with tractable skills scores can ease the transition from training session to clinical practice. Use of these training scenarios within a perfusion education system also has the advantage of providing an index of trainees’ current proficiency and improvement by providing tractable skill scores. In conclusion, the use of ECCSIM-Lite simulations, together with evaluation of task accomplishment over repeated training sessions, is an effective method of basic skill training for perfusionists

Development of a New Pulsatile Ventricular Assist Device

We developed a small, lightweight, low-cost implantable ventricular assist device (VAD) for use in smaller Japanese subjects. The major advantage of this pump is the simplicity of its fabrication. Most parts of the pump were shaped from a transparent acrylic block by a turning process, and the diaphragm was made from a silicon sheet. Since this method of construction did not require any complex processes, we could manufacture many pumps of various shapes. We determined the most efficient shape for the Ebacor VAD using the flow visualization technique. The pump showed an output above 6 liters/min under a driving pressure of 300/-100 mmHg. The pump performance of current VADs is superior to that of the Ebacor VAD, because these pumps are larger. Since the Ebacor VAD is small in size, it can be driven by the driving system of a normal IABP control unit, which many hospitals already have in place. During a 30day continuous driving performance test of this pump, no problems like performance decrements or water and air leakage were observed

Epicardial Atrial Mapping Can Predict Elimination of Chronic Atrial Fibrillation After the Box Pulmonary Vein Isolation During Mitral Valve Surgery

Background: The pulmonary veins (PV) and posterior left atrium (LA) may contribute to the occurrence and maintenance of atrial fibrillation (AF). We evaluated whether simple epicardial electrophysiological mapping can predict elimination of chronic AF after the box PV isolation procedure. Methods and Results: Using a computerized 48-channel mapping system, we performed intraoperative atrial mapping in 16 patients with chronic AF associated with mitral valve (MV) disease. Patients' ages ranged from 48 to 76 years (mean, 61.4 years). AF duration ranged from 1 to 16 years (mean, 7.5 +/- 5.4 years). Simple box PV isolation was performed during the MV operation. Regular and repetitive activation was found in the LA of 12 of 16 patients, and irregular and chaotic activation was found in both atria in 4 of 16 patients; 12 patients with regular and repetitive activation of the LA were treated by box PV isolation and the other 4 patients with irregular and chaotic activation in both atria did not recover sinus rhythm after this procedure. AF-free rate was significantly higher in patients with regular and repetitive activation of the LA (P < 0.01). Conclusions: Box PV isolation was effective in the treatment of chronic AF associated with MV disease. Epicardial atrial mapping may predict elimination of AF after the box PV isolation. (Circ J 2012; 76: 852-859