Is 300 Seconds ACT Safe and Efficient during MiECC Procedures?

INTRODUCTION: The recommended minimum activated clotting time (ACT) level for cardiopulmonary bypass (CPB) of 480 seconds originated from investigations with bubble oxygenators and uncoated extracorporeal circulation (ECC) systems. Modern minimal invasive ECC (MiECC) systems are completely closed circuits containing a membrane oxygenator and a tip-to-tip surface coating. We hypothesized that surface coating and the "closed-loop" design allow the MiECC to safely run with lower ACT levels and that an ACT level of 300 seconds can be safely applied without thromboembolic complications. The aim of this study was to investigate the potential risks during application of reduced heparin levels in patients undergoing coronary surgery. METHODS: In this study, 68 patients undergoing coronary artery bypass grafting with MiECC were randomized to either the study group with an ACT target of 300 seconds or the control group with an ACT of 450 seconds. All other factors of MiECC remained unchanged. RESULTS: The study group received significantly less heparin and protamine (heparin [international units] median [min-max], Red_AC: 32,800 [23,000-51,500] vs. Full_AC: 50,000 [35,000-65,000] p < 0.001; protamine [international units], Red_AC: 18,000 [10,000-35,000] vs. Full_AC: 30,000 [20,000-45,000] p < 0.001). The ACT in the study group was significantly lower at the start of MiECC (mean ± standard deviation: study group 400 ± 112 vs. control group 633 ± 177; p < 0.0001). Before termination of CPB the ACT levels were: study group 344 ± 60 versus control group 506 ± 80. In both groups, the values of the endogenous thrombin potential (ETP) decreased simultaneously. None of the study participants experienced thromboembolic complications. CONCLUSION: Since no evidence of increased thrombin formation (ETP) was found from a laboratory standpoint, we concluded that the use of MiECC with a reduced anticoagulation strategy seems possible. This alternative anticoagulation strategy leads to significant reduction in dosages of both heparin and protamine. We can confidently move forward with investigating this anticoagulation concept. However, to establish clinical safety of ACT below 300 seconds, we need larger clinical studies.

Shed-blood-separation and cell-saver: an integral Part of MiECC? Shed-blood-separation and its influence on the perioperative inflammatory response during coronary revascularization with minimal invasive extracorporeal circulation systems - a randomized controlled trial.

OBJECTIVE: The postoperative systemic inflammatory response after cardiopulmonary bypass (CPB) is still an undesirable side-effect after cardiac surgery. It is most likely caused by blood contact with foreign surfaces and by the surgical trauma itself. However, the recirculation of activated shed mediastinal blood is another main cause of blood cell activation and cytokine release. Minimal invasive extracorporeal circulation (MiECC) comprises a completely closed circuit, coated surfaces and the separation of suction blood. We hypothesized that MiECC, with separated cell saved blood, would induce less of a systemic inflammatory response than MiECC with no cell-saver. The aim of this study was, therefore, to investigate the impact of cell washing shed blood from the operating field versus direct return to the ECC on the biomarkers for systemic inflammation. MATERIAL AND METHODS: In the study, patients with MiECC and cell-saver were compared with the control group, patients with MiECC and direct re-transfusion of the drawn blood shed from the surgical field. RESULTS: High amounts of TNF-α (+ 120% compared to serum blood) were found in the shed blood itself, but a significant reduction was demonstrated with the use of a cell-saver (TNF-α ng/l post-ECC 10 min: 9.5±3.5 vs. 19.7±14.5, p<0.0001). The values for procalcitonin were not significantly increased in the control group (6h: 1.07±3.4 vs. 2.15±9.55, p=0.19) and lower for C-reactive protein (CRP) (24h: 147.1±64.0 vs.134.4±52.4 p=0.28). CONCLUSION: The use of a cell-saver and the processing of shed blood as an integral part of MiECC significantly reduces the systemic cytokine load. We, therefore, recommend the integration of cell-saving devices in MiECC to reduce the perioperative inflammatory response.

Use of minimal invasive extracorporeal circulation in cardiac surgery: principles, definitions and potential benefits. A position paper from the Minimal invasive Extra-Corporeal Technologies international Society (MiECTiS).

Minimal invasive extracorporeal circulation (MiECC) systems have initiated important efforts within science and technology to further improve the biocompatibility of cardiopulmonary bypass components to minimize the adverse effects and improve end-organ protection. The Minimal invasive Extra-Corporeal Technologies international Society was founded to create an international forum for the exchange of ideas on clinical application and research of minimal invasive extracorporeal circulation technology. The present work is a consensus document developed to standardize the terminology and the definition of minimal invasive extracorporeal circulation technology as well as to provide recommendations for the clinical practice. The goal of this manuscript is to promote the use of MiECC systems into clinical practice as a multidisciplinary strategy involving cardiac surgeons, anaesthesiologists and perfusionists.

A retrospective comparative study of minimally invasive extracorporeal circulation versus conventional extracorporeal circulation in emergency coronary artery bypass surgery patients: a single surgeon analysis.

OBJECTIVES: At the moment, the main application of minimally invasive extracorporeal circulation (MiECC) is reserved for elective cardiac operations such as coronary artery bypass grafting (CABG) and/or aortic valve replacement. The purpose of this study was to compare the outcome of emergency CABG operations using either MiECC or conventional extracorporeal circulation (CECC) in patients requiring emergency CABG with regard to the perioperative course and the occurrence of major adverse cardiac and cerebral events (MACCE). METHODS: We analysed the emergency CABG operations performed by a single surgeon, between January 2007 and July 2013, in order to exclude the differences in surgical technique. During this period, 187 emergency CABG patients (113 MiECC vs 74 CECC) were investigated retrospectively with respect to the following parameters: in-hospital mortality, MACCE, postoperative hospital stay and perioperative transfusion rate. RESULTS: The mean logistic European System for Cardiac Operative Risk Evaluation was higher in the CECC group (MiECC 12.1 ± 16 vs CECC 15.0 ± 20.8, P = 0.15) and the number of bypass grafts per patient was similar in both groups (MiECC 2.94 vs CECC 2.93). There was no significant difference in the postoperative hospital stay or in major postoperative complications. The in-hospital mortality was higher in the CECC group 6.8% versus MiECC 4.4% (P = 0.48). The perioperative transfusion rate was lower with MiECC compared with CECC (MiECC 2.6 ± 3.2 vs CECC 3.8 ± 4.2, P = 0.025 units of blood per patient). CONCLUSIONS: In our opinion, the use of MiECC in urgent CABG procedures is safe, feasible and shows no disadvantages compared with the use of CECC. Emergency operations using the MiECC system showed a significantly lower blood transfusion rate and better results concerning the unadjusted in-hospital mortality.

Interhospital air transport of a blind patient on extracorporeal life support with consecutive and successful left ventricular assist device implantation.

The use of extracorporeal life support systems (ECLS) in patients with postcardiotomy low cardiac output syndrome (LCO) as a bridge to recovery and bridge to implantation of ventricular assist device (VAD) is common nowadays. A 59-year-old patient with acute myocardial infarction received a percutaneous transluminal angioplasty and stenting of the circumflex artery. During catheterization of the left coronary artery (LAD), the patient showed ventricular fibrillation and required defibrillation and cardiopulmonary resuscitation. After implantation of an intra-aortic balloon pump, the patient immediately was transmitted to the operating room. He received emergency coronary artery bypass grafting in a beating heart technique using pump-assisted minimal extracorporeal circulation circuit (MECC). Two bypass grafts were performed to the LAD and the right posterior descending artery. Despite initial successful weaning off cardiopulmonary bypass with high-dose inotropic support, the patient presented postcardiotomy LCO and an ECLS was implanted. The primary setup of the heparin-coated MECC system was modified and used postoperatively. As a result of the absence of an in-house VAD program, the patient was switched to a transportable ECLS the next day and was transferred by helicopter to the nearest VAD center where the patient received a successful insertion of a left VAD 3 days later.

In vitro comparison of the new in-line monitor BMU 40 versus a conventional laboratory analyzer.

Reliable information about different blood parameters is essential in maintaining hemodynamics, perfusion, and gas exchange during cardiopulmonary bypass (CPB). For this purpose, a precise and continuous monitoring is needed. The objective of this in vitro study was to compare a novel continuous in-line blood parameter monitoring system versus a reference laboratory analyzer. The study was conducted as an in vitro prospective experimental study during a CPB simulation. The reliability of BMU 40 was tested in monitoring the pO2, oxygen saturation (SO2), and hematocrit (Hct) under physiological and extreme conditions with regards to temperature, oxygenation, and blood concentration. Four different tests were performed and conducted with five sensors each. Correlation analyses and Bland-Altman analyses were performed. A total of 350 measurement points were compared. All monitored values of blood parameters correlated highly with laboratory values (all r values >.90). Test 1: Biases of pO2 (act) varied from -3.24 mmHg (+/- 6.86 mmHg) up to 6.0 mmHg (+/- 17.89 mmHg). The biases of pO2 (37 degrees C) ranged from -3.52 mmHg (+/- 6.01 mmHg) up to 68.8 mmHg (+/- 67.82 mmHg). Test 2: The biases standard deviations (SD) for Hct ranged from -0.35% (+/- .79%) up to 2.35% (+/- .91%). The biases (SD) for SO2 varied from -.45% (+/- .86%) up to .85% (+/- 1.01%). Test 3: The biases (SD) of Hct ranged from -1.00% (+/- 1.84%) up to -.67% (+/- 1.49%). Test 4: The biases (SD) for SO2 varied from -.36% (+/- 1.60%) up to .48% (+/- .90%).The BMU 40 is a reliable device in measuring the partial oxygen pressure (pO2), SO2, and Hct under normal physiological and extreme conditions with regards to temperature, oxygenation, and blood concentration in simulation of CPB. The algorithm to calculate pO2 (37 degrees C) under hypothermic conditions needs to be adjusted. (Before the official market launch a new software version of the BMU 40 has been developed. The algorithm to calculate pO2 (37 degrees C) under hypothermic conditions has been improved and the miscalculation eliminated.)

Clinical evaluation of the new BMU 40 in-line blood analysis monitor.

BACKGROUND: Accurate information about different blood parameters is essential in maintaining haemodynamics, perfusion and gas exchange during cardiopulmonary bypass (CPB). For this purpose, precise, accurate and continuous measurement and monitoring, preferably visually available, is needed.The objective of this clinical study was to compare the newly developed continuous in-line blood parameter monitoring system (CIBPMS) BMU 40 with a reference laboratory analyser with regards to the precision and accuracy of blood parameter measurement. METHODS: Thirty adult patients underwent elective cardiac surgery, CPB and mild hypothermia (32 degrees C). At five predetermined time points (S1 - S5) arterial and venous blood samples were analysed using the BMU 40 for five different parameters (PaO(2)(37 degrees C), PaO(2)(act), SvO(2), Hb(ven) and Hct(ven)) and these results were compared to the gold standard laboratory analyser, the ABL 700. RESULTS: A total of 150 paired blood samples were included to compare means, to analyse correlation, and to calculate measures of bias, precision, limits of agreement and 95% confidence intervals. Results revealed good agreement between the two devices for all parameters. Bias +/- precision of S2 - S5 PaO( 2)(37 degrees C) were: 2.17 +/- 9.61; PaO(2)(act) 2.58 +/- 9.54; SvO(2) -1.44 +/- 2.35; Hb(ven) 0.01 +/- 0.42; Hct(ven) 0.04 +/- 1.29. Statistically significant differences were detected for SvO(2) (p<0.00001) at S1. Correlations after this first time point (S1) improved following an in vivo calibration. CONCLUSION: The BMU 40 is a precise, accurate and reliable continuous in-line blood parameter measuring system that can easily be used within a standard CPB setup. However, present data suggest an in vivo calibration of the BMU 40 should be performed.