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DOI: 10.5301/IJAO.2011.7727 Int J Artif Organs 2011 ; 34 ( 4): 365- 373 ORIGINAL ARTICLE Extracorporeal membrane oxygenation in 108 patients with low cardiac output – a single-center experience Andres Beiras-Fernandez*, Marcus-André Deutsch*, Sandra Kainzinger, Ingo Kaczmarek, Ralf Sodian, Peter Ueberfuhr, Bruno Meiser, Michael Schmoeckel, Bruno Reichart, Paolo Brenner Department of Cardiac Surgery, Grosshadern University Hospital, Ludwig-Maximilians-University (LMU) Munich Germany *A Beiras-Fernandez and M-A Deutsch contributed equally to this work ABSTRACT Background: For short-term ventricular and pulmonary support the extracorporeal membrane oxygenation (ECMO) system using the Bio-Medicus centrifugal pump (Medtronic®, Minneapolis, MN, USA) was applied in 108 patients with cardiac low-output. Methods: From December 1996 to July 2006 the ECMO was implanted in 108 patients (73 adult, mean age: 49.3±18.0 yrs and 35 children, mean age: 1.3 ± 2.7 yrs) with mostly postcardiotomy cardiac low output. The surgical procedures included congenital heart surgery (n=35), heart transplantation (HTx) (n=21), coronary artery bypass operation (CABG) and/or valvular operation (n=33), other operations (n=6) and 13 patients with ECMO support for bridge to recovery. Results: The mean supporting time was 5.1±5.6 days. Overall, 30-day-survival was 40.2%. Best survival rates were seen after congenital heart surgery (24/35, 65.7%) and after HTx (9/21, 42.9%); the worst rates were in the group of CABG and/or valvular operations (5/33, 15.2%), only ECMO support (3/13, 23.1%) and other operations (1/6, 16.7%). Fifty-four patients died while supported by ECMO, 15 were weaned from ECMO but died in hospital, 39 patients were weaned and survived. Causes of death were multi-organ failure (40.6%), bleeding (23.2%), persistent cardiac low output (21.7%), thrombembolic events (8.7%), and graft failure (5.8%). Markers for adverse outcome were identified as older age, high body weight, increased AST/GOT levels, and lower thrombocyte count in adults; and as higher levels of serum creatinine in pediatric patients. Conclusions: ECMO support showed best results in pediatric patients after congenital heart surgery and in patients after HTx in contrast to multimorbid, older patients with often irreversible myocardial damage. KEY WORDS: Low cardiac output, ECMO, VAD, Acute heart failure, Heart surgery Accepted: January 24, 2011 INTRODUCTION Although surgical techniques and methods for myocardial protection have been continuously improved over the last few decades, low cardiac output is seen frequently in the perioperative phase during and after weaning from cardiopulmonary bypass (CPB) (1, 2). The etiology of car- diac low-output is often multifactorial but includes myocardial ischemia during cross-clamping, reperfusion injury, cardioplegia-induced myocardial dysfunction, systemic inflammatory response syndrome, and pre-existing myocardial damage (3). The majority of these patients can successfully be managed by intensified inotropic drug therapy or intra-aortic balloon counterpulsation (IABP). Neverthe- © 2011 Wichtig Editore - ISSN 0391-3988 365 ECMO for low cardiac output syndrome less, a small proportion of patients who are refractory to conventional treatment need additional mechanical circulatory support postoperatively. Extracorporeal membrane oxygenation (ECMO) is a modified form of cardiopulmonary bypass which can successfully be used to transitionally provide mechanical circulatory support in patients with low cardiac output and pulmonary failure. The aim of this support is to stabilize hemodynamics, to simultaneously unload the heart in order to gain time for the recovery of stunned myocardium, and to guarantee adequate blood supply of the other vital organs. Distinct advantages in this setting are rapid delivery of adequate blood flow for unloading of the left and right ventricles, and adequate oxygenation without the deleterious effects of high dose inotropic medication and high-inspired oxygen, and the possibility to regulate the systemic body temperature (4). However, although ECMO support as a therapeutic means in neonates and pediatric patients is well established, its role in adults is less well scrutinized and morbidity as well as mortality is considerable. Criteria for ECMO implantation in adults are not precisely defined. Furthermore, there is limited knowledge and controversy about the factors predictive of survival. Thus, the objective of this single-center study was to review the outcome of all patients who received ECMO sup- port for cardiac low output after cardiac surgery and to identify measurable variables predictive of adverse events and mortality in our patients. PATIENTS AND METHODS Patient population and indications for ECMO implantation Between December 1996 and July 2006 a total of 15662 patients underwent cardiac surgical intervention with the use of cardiopulmonary bypass in the Grosshadern Clinic in Munich. During this time, ECMO was implanted for mechanical circulatory support in 108 patients (mean age: 33.8±27.0 years) with low cardiac output. Overall, 73 adult (50 male/23 female patients) and 35 pediatric patients were connected to ECMO support after failure to be weaned from cardiopulmonary bypass. The surgical procedures are listed in Table I. Mean age of adult patients was 49.3±18.0 years and 1.3±2.7 in pediatric patients, mean duration in days of ECMO support was 4.4±4.0 in adult and 7.0±8.0 in pediatric patients. A number of 36 patients (49.3%) were either on intra-aortic balloon counterpulsation before TABLE I - PATIENT DEMOGRAPHICS AND SURGICAL DATA (N = 108) Parameter Adult Patients Pediatric Patients Gender, male/female Age (years) Body weight (kg) Height (cm) BMI (kg/m²) BSA (m²) Primary indications for surgery 47/26 49.3 ± 8.0 77.6 ± 19.8 175.1 ± 9.7 25.27 ± 5.78 1.91 ± 0.22 CABG and/or valve CABG CABG and valve Mitral valve Other valve Double valve Post-HTx Emergency ECMO Others 22/13 1.3 ± 2.7 11.2 ± 6.1 78.9 ± 16.6 17.2 ± 4.1 0.41 ± 0.21 Congenital TGA Fallot Norwood I Emergency Others CPB time (min) Aortic clamp time (min) IABP (only adults) (n) Mean ECMO duration (d) Redo sternotomy (n) 254.3 ± 18,3 110.9 ± 14.0 36 (49.3%) 5.14 ± 5.6 43 (39.8%) 366 33 (31%) 14 6 6 6 1 21 (19%) 13 (12%) 6 © 2011 Wichtig Editore - ISSN 0391-3988 290.1 ± 22,3 110.5 ± 12.2 - 35 (32%) 9 5 5 9 7 Beiras-Fernandez et al surgery or it was instituted in addition to ECMO support. Mean aortic cross-clamping time was 110.9±4.0 minutes in adults and 110.5±12.2 minutes in children. Mean bypass time was 254.3±18.3 minutes in adults and 290.1±22.3 minutes in children. Intraoperatively, ECMO support was considered on a caseby-case basis in patients who failed to be weaned from cardiopulmonary bypass. Patients were considered for ECMO implantation if they had a cardiac index less than 2 l/min/ m² with systolic blood pressure of 75 mm Hg, a pulmonary capillary wedge pressure (PCWP) of more than 20 mm Hg, a maximum oxygen uptake of <12 ml/min/kg body weight despite adequate filling pressures, the use of maximal inotropic pharmacological support and/or intra-aortic balloon counterpulsation. ECMO was our first choice of mechanical support independently of associated pulmonary damage for various reasons, including the rapid implantation, the absence of further cardial damage, and the possibility of bridging to another VAD under elective conditions. ECMO circuit design and patient management The Bio-Medicus Perfusion system consisted of a Carmeda Bioactive Surface-coated circuit made of polyvinyl tubing (Carmeda®; Vasby, Sweden), a centrifugal blood pump (Bio-Pump, Medtronic®, Minneapolis, MN, USA: 50 cc pump head when flow <1.5 l/min; an 80 cc pump head when flow >1.5 l/min was required), a hollow-fiber oxygenator (Medos® Hilite 7000 LT or 2400 LT, Stolberg, Germany), a heater/cooler unit, and an oxygen saturation/ hematocrit monitor (Medtronic®, Minneapolis, MN, USA). All surfaces in contact with blood were heparin coated. For safety reasons, the circuit was equipped with two oxygenators which were assembled in parallel. Cannulation was performed via the ascending aorta and right atrium in most patients. In patients failing to wean from CPB, the cannulas in the right atrial (adults: 28 F Medtronic two-stage cannula; Medtronic, Minneapolis, MN, USA) and ascending aorta (Adults: 22 F EOPA© arterial cannula; Medtronic, Minneapolis, MN, USA) were left in place and then connected to the ECMO. The chest was mostly left open, covered by a sterile adhesive plastic or Esmarch membrane. In emergency cases, transfemoral cannulation was used (preferred cannulae: arterial 16-18 F EOPA© arterial cannula; Medtronic, Minneapolis, MN, US; venous: 19-21 F Biomedicus Multistage; Medtronic, Minneapolis, US). Mechanical ventilation was continued in order to achieve oxygenation and CO2 elimination. Positive end-expiratory pressure was adjusted to a level of 10 cm H2O for the prevention of atelectasis. All patients were anticoagulated as follows. Heparin was administered intravenously to maintain an activated clotting time (ACT) of 160-200 seconds (s) and a PTT of 60 to 80 s to prevent coagulation in the ECMO. Procoagulative products and platelets were administered to maintain platelets >100-150 x 109, fibrinogen >2.0 g/l and a prothrombin time <14 s. Red packed blood cells were used when hemoglobin level was lower than 8-9 mg/dl. In order to minimize third-space fluid accumulation in patients with renal failure, excessive crystalloid administration was avoided and hemofiltration was used. The hemodynamic management was targeted to maintain a mean blood pressure level of 70-80 mm Hg. For adequate systemic circulatory support a blood flow of at least 2.0 to 2.5 l/min/m² was warranted with a target of a mixed venous oxygen saturation of more than 70%. Oxygen flow was gradually adjusted as necessary to meet the oxygen requirements according to repetitive blood gas sample measurements. All patients were supported with the intention to wean from ECMO. Statistics Patient cumulative survival was calculated using KaplanMeier analysis. Differences in actuarial survival were determined by the log-rank test. For univariate analysis of continuous variables Student’s t-test was performed. Categorical variables are expressed as percentages and were analyzed with the Fisher’s exact test. All analyses were performed using SPSS software (version 15.0 for Windows, SPSS, Chicago, IL, US). A p-value <0.05 was considered statistically significant. All parameter are expressed as mean ± standard deviation or ± standard error of the mean (SEM) when indicated. RESULTS ECMO support was required by 0.7% of all patients undergoing cardiac surgery including transplantation. The mean supporting time was 5.1±5.6 days. In adults, mean supporting time was 4.4±4.0 days (survivors: 6.5±4.7 days, non-survivors: 3.8±3.7 days), in children 7.0±8.0 days (survivors: 4.6±1.8 days, non-survivors: 10.5±11.9 days). Fifty-four patients (50%) died while supported by ECMO, © 2011 Wichtig Editore - ISSN 0391-3988 367 ECMO for low cardiac output syndrome Fig. 1 - Overall 30-day survival (left). Survival based on patient age (age 0-14 vs. others: p<0.05) (right). Fig. 2 - Causes of death (p<0.05 in all causes of death of adults vs. children). while 15 (13.9%) were weaned from ECMO but died in hospital. The 30-day-survival was 40.7%, after 50 days it was still 38.9% and after 100 days 38.0%. We documented a total survival of 36.1% after a 1-year follow-up. After an average of 33.5 days in the intensive care unit a total of 39 patients survived and were discharged (Fig. 1). When looking at survival related to the primary indication for support, best 30-day-survival was seen in the group with congenital heart surgery (74.3%) and heart transplantation (42.9%). Worst survival rates were found in the group of ECMO after cardiogenic shock as a means of bridge-torecovery (23.1%), and after CABG and/or valvular operations (15.2%). A separate statistical analysis of the adult 368 patients was performed: 5 patients died during the first 24 hours, 17 died the second day (during the first 24 to 48 hours), further 11 died during the first 48 to 96 hours. Only 40 adult patients could survive more than four days, 24 of these patients died in the following days. In children, the first patient died on the second day of ECMO support. One child died after 48 to 96 hours. The remaining 33 children survived more than 96 hours, while 10 died in the further follow-up. The main cause of death was multi-organ failure (MOF) with refractory ventricular failure (40.6%) during support. Other reasons for mortality were coagulopathyrelated profuse bleeding (23.2%), isolated persistent low cardiac output (21.7%), thrombembolic events (8.7%), and allograft failure (5.8%) (Fig. 2). When comparing parameters of survivors and non-survivors in the univariate analysis we found that in adults, patients over 60 years of age were less likely to survive (p=0.038) (Fig. 3). The mean age of surviving patients was 16.7±21.9 years versus 43.6±24.8 years of the deceased patients (Tab. II). The other 15 survivors in adult patients were younger than 60 years. Other parameters which predicted an unfavorable outcome in adults were higher body weight with the corresponding higher body surface area (BSA). A significantly better survival (p<0.001) was evident in patients up to 60 kg body weight (Fig. 4). Similarly, we could not find a significant difference for the cardiopulmonary bypass time or aortic clamp time when comparing survivors and non-survivors. A subgroup data analysis of 86 patients showed that in 41 (47.7 %) of these patients the intraoperative bypass time was longer than 4 hours. Overall, 28 of these 41 died (68.3 %). Of our 45 patients with a bypass time longer than four hours, 27 (60%) did not survive. In 16 (18.6%) of all patients, intraoperative © 2011 Wichtig Editore - ISSN 0391-3988 Beiras-Fernandez et al Fig. 3 - Survival rates based on adult patient body weight (kg) (body weight 0- 60 vs. >60: p<0.05). bypass time was longer than 6 hours. Of these patients 12 (75%) died in course of the ECMO therapy. These results cannot show a statistically significant advantage of shorter bypass time for patient survival. The use of an IABP also showed a trend but no significant effect on mortality (p=0.5). Patient gender did not influence survival rates. In adults, 21.7% of female and 22.0% of male patients survived. Within the pediatric group, 68.8% of the girls and 63.2% of the boys survived. Redo-sternotomy for bleeding was necessary in 37 adults and in 6 children. Of these 43 patients, 30 died (28 adults). No statistically significant disadvantage for patients with redo-sternotomy could be observed (Tab. II). Adult patients after HTx were separately compared with the other adult patients. Of all 21 heart transplanted adults, 9 patients survived after ECMO (42.9%). Within the other groups of the resting 52 adult patients, only 7 survived (13.5%) after one year. Results are shown in Figure 5 comparing outcomes of congenital heart surgery with heart transplantation and other groups (p=0.008). The best survival rate was seen in the group with congenital heart surgery (24/35, 65.7%), significantly higher than after HTx (9/21, 42.9%). Both groups had significantly better survival rates than the group with CABG and valvular operations (5/33, 15.2%). Univariate analysis of common laboratory markers revealed that in adults non-survivors had mean AST/GOT levels of 656±640 IU/l after 72 hours if compared to 172±263 IU/L in survivors (p=0.010). Platelet count after 24 and 72 hours was significantly lower in non-survivors if compared with survivors (p=0.001 and p=0.023). For hemoglobin, bilirubin, serum creatine kinase (CK), and creatinine no significant difference could be observed (Tab. III). Within the pediatric group we found a significant difference (p=0.023) in levels of creatinine after 72 hours (0.8±0.4 m/dL in survivors, 1.3±0.8 mg/dL in non-survivors) (Tab. III). Altogether significantly better routine laboratory parameters could be seen in survivors. For a better evaluation of the single factors influencing TABLE II - SURVIVOR AND NON-SURVIVOR CHARACTERISTICS OF ADULT PATIENTS Female gender Age (years) Weight (kg) Height (cm) BSA (m²) Primary indication for Cardiac surgery CABG and/or valve (n) Post-HTx (n) Emergency ECMO (n) Others (n) IABP (n/%) Aortic clamp time (min) CBP time (min) Duration of support (d) Survivors Non-survivors P value 5/31,3% 39.3±21.0 63±12.3 178±12.9 1.79±0.2 18/31,6 % 58.1±15.1 80±17.1 174±8.1 1.94±0.2 0.872;n.s. 0.008 0.002 0.24;n.s. 0.037 4 9 3 0 6/37.5 % 92±43 212±104 6.5±4.7 29 12 10 6 30/52,6 % 116±118 266±146 3.8±3.7 0.5;n.s. 0.504;n.s. 0.234;n.s. 0.023 . (n.s. = not significant) © 2011 Wichtig Editore - ISSN 0391-3988 369 ECMO for low cardiac output syndrome TABLE III - LABORATORY VARIABLES OF SURVIVORS AND NON-SURVIVORS All a) Adults Hemoglobin (g/dL) Bilirubin (mg/dL) Creatinine (mg/dL) CK (IU/L) Thrombocytes AST/GOT (IU/L) b) Children hemoglobin (g/dL) Bilirubin (mg/dL) Creatinine (mg/dL) CK (IU/L) Thrombocytes AST/GOT (IU/L) Survivors Non-survivors P value 24h 72h pre-op 24h 72h pre-op 24h 72h 24h 72h (G/l) 72h 24h 72h 8.8±1.7 9.3±1.2 2.6±5.3 3.4±3.4 4.4±3.5 1.8±1.1 2.0±0.9 2.1±0.8 246±4297 2931±4319 24h 87±81 82±104 1261±2499 495±587 9.1±1.4 9.3±1.3 1.8±1.6 3.8±2.2 4.1±3.4 1.5±0.5 1.7±0.5 1.9±0.7 824±911 1178±2236 147±133 133±169 215±209 172±263 8,8±1,8 9.4±1.2 2.9±6.1 3.2±3.7 4.5±3.6 1.9±1.3 2.1±1.1 2.3±0.8 2910±4739 3807±4851 72±51 57±25 1573±2775 656±640 0.466; n.s. 0.774; n.s. 0.540; n.s. 0.584; n.s. 0.765; n.s. 0.267; n.s. 0.210; n.s. 0.130; n.s. 0.108; n.s. 0.062; n.s. 0.001 0.023 0.074; n.s. 0.010 24h 72h pre-op 24h 72h pre-op 24h 72h 24h 72h (G/l) 72h 24h 72h 11.3±1.7 11.5±1.1 2.8±2.4 2.9±2.3 3.5±3.7 0.8±0.5 0.9±0.5 1.0±0.6 1118±1862 528±734 24h 173±112 127±67 511±999 481±1499 11.4±1.6 11.3±1.1 2.5±2.0 2.5±1.3 2.8±2.9 0.7±0.2 0.8±0.4 0.8±0.4 1469±2250 615±819 185±110 136±56 454±903 201±272 11.0±1.8 12.0±0.9 3.5±3.3 3.6±3.4 5.0±4.8 0.9±0.8 1.2±0.7 1.3±0.8 512±557 354±520 149±118 109±85 626±1215 1072±2614 0.478;n.s. 0.062;n.s. 0.336;n.s. 0.171;n.s. 0.129;n.s. 0.173;n.s. 0.052;n.s. 0.023 0.180;n.s. 0.367;n.s. 0.386; n.s. 0.320;n.s. 0.666;n.s. 0.154,n.s. (n.s.= not significant). patient survival a multivariate analysis using the Cox regression model was performed. Only patients age could be found as an independent predictive factor with better results in young patients. DISCUSSION Critical hemodynamic compromise in terms of postcardiotomy myocardial dysfunction is encountered in approximately 2% to 6% of all patients undergoing routine cardiac surgery procedures (1, 2). The majority of these patients can be managed with intensified inotropic support and/ or short-term mechanical support with IABP. Fortunately, more advanced circulatory assistance is necessary in only 0.2% to 1.2% of patients. Similarly, in our experience, 370 0.7% of all patients undergoing cardiac surgery including transplant procedures required ECMO support. ECMO is the most common form used for initial support after failure to wean from extracorporeal circulation or for delayed postoperative cardiogenic shock. In most institutions ECMO is rapidly available, providing both emergent cardiac and pulmonary support; it is easy to apply, and compared to other mechanical assist devices is rather inexpensive (3). Additionally, in contrast to VADs, ECMO can provide pulmonary support. During postcardiotomy, low output ECMO can be easily connected to the cannulas used for cardiopulmonary bypass. A percutaneous transfemoral cannulation can be set up at bedside. Consequently, fewer bleeding complications and less sedation can be observed if compared with VADs (6). As stated by Magovern et al, transthoracic cannulation is preferred by virtue of the pos- © 2011 Wichtig Editore - ISSN 0391-3988 Beiras-Fernandez et al sibility to more effectively increase available flow rate when compared to the femoral access. Further advantages of central cannulation include a better unloading of the ventricles, and a reduction in the risk of peripheral vascular complications. Disadvantages of central cannulation include an increased bleeding rate, which could be documented in our patients in comparison to transfemoral access, without having any relevance upon survival (7). However, several disadvantages have to be kept in mind when considering ECMO support. First, ECMO is not designed for long-term support, since mobilization of the patient is heavily limited. Moreover, patients with thoracic application of the ECMO cannula need to be sedated and often the chest cannot be closed. Besides, ECMO support leads to severe platelet activation loss and dysfunction with possibilities of profound bleeding and/or stroke. The results of our retrospective study show an overall 30-day-survival of 41% (adults: 25%, children: 74%). If compared with results of other study groups, the variant survival rates (22-47%) between different studies might in part be influenced by patient selection and the doubtful reasonable employment of ECMO as an ultima ratio therapy. The outcome of patients that were placed on ECMO in the postoperative period is considerably better if compared with patients in whom ECMO is required to separate them from extracorporeal circulation (8). Fiser et al tried to establish guidelines to simplify the decision when to discontinue ECMO support as a bridge-to-recovery. They concluded that after 48 to 72 hours, consideration should be given to move to an implantable long term VAD (ECMO as a bridge-to-bridge) or to stop support, except in patients after heart transplantation (9, 10). The duration of ECMO support in our collective was considerably longer when compared with the almost 5-day duration seen in other study groups, given that our survivors were supported for a period of 6.5 ± 4.7 days. Our strategy was to provide sufficient time to recover from myocardial injury, especially in patients after HTx being supported for 6.0 ± 5.0 days. In our patients secondary MOF was the most frequent causes of death. In a prospective study Rastan et al evaluated the autopsy findings of 78 patients who died on ECMO support. Clinically unrecognized postoperative complications and unexpected causes of death were found by autopsy in 76% and 28% of all patients, respectively, including a high incidence of venous thrombus formation and fatal events secondary to local and systemic thrombembolic events (11). These results demonstrate that anticoagulation during ECMO therapy is still suboptimal to prevent thrombembolic events and avoid bleeding in patients with MOF. Several risk factors for the postoperative mortality were shown in the literature. They include older age (over 50 years old), extended aortic operations, shorter aortic clamp time, shorter height, rethoracotomy, previous myocardial infarction, and lack of IABP (1, 6, 7, 12). In our study we observed a significantly better survival of the under 60-year-old adult patients. We also observed that patients with higher body weight and larger body surface area had a higher risk for mortality during support. Therefore, these patients might benefit from more advanced forms of mechanical circulatory support and could be considered for primary VAD implantation. ECMO support in our adult patients after cardiac transplantation had a significantly better outcome than after other procedures. Magovern et al described the use of early post-transplant use of ECMO for providing support after early graft failure due to pulmonary hypertension refractory to inhaled nitric oxide and pulmonary vasodilators resulting in right ventricular overload and dysfunction, a potentially reversible condition (7). ECMO support in neonatal and pediatric patients is a well established concept and a good outcome has been described (15-18). ECMO implantation in our pediatric patients resulted in a good outcome, with 74.3% survival rate after 30 days. The malformations of the immature myocardium result in liability to postoperative heart failure and cardiac low output (15). Balsubramanian et al described neurological complications after cardiopulmonal resuscitation, bleeding, and cardiac arrhythmia in their pediatric patients (18). Especially in children, increasing renal failure is seen as a risk factor for mortality under ECMO support (19, 20). The adverse alteration of serum creatinine in our non-survivors provides striking confirmation of this observation. In adult non-survivors, thrombocyte counts were lower after 24 hours as well as after 72 hours. This is compatible with higher blood loss. In pediatric patients, higher thrombocyte counts were found because of fewer bleeding complications. Due to the existence of thrombocytopenia and thrombocyte dysfunction there is also an increased risk of intracranial bleeding with a mortality of 92.3% (21, 22). A reasonable level of anticoagulation, prevention of renal failure, and aggressive replacement of thrombocytes must be aimed for. In all patients AST/GOT was massively elevated. © 2011 Wichtig Editore - ISSN 0391-3988 371 ECMO for low cardiac output syndrome In adult non-survivors it was even 7 times higher than in survivors. Serum creatinine levels as a marker for renal failure were constantly elevated in adults and higher levels were registered in non-survivors. Comparing CK of survivors with non-survivors, a trend for the benefit of survivors could be observed (p=0.11 after 24 h, p=0.06 after 72 h). In conclusion, several laboratory parameters can describe the patients’ state of health and progression of MOF or recovery. Smedira et al assessed a decreased survival rate in older patients with higher levels of creatinine and bilirubin (12). The specific series of routine laboratory values we have discussed above are predictive for patients prognosis, they can help to identify potential complications, and offer guidance on how to proceed. In the future, it will be of interest to know the extent to which third-generation blood pumps with higher blood flow rates and reduced contact activation of blood cells, along with coagulation components with potentially less systemic inflammatory response, will improve the outcome of ECMO patients. Magnetic-levitation blood pumps deserve attention in particular since they allow the suspension of the blood impeller without any mechanical contact, thus eliminating wear that takes place at the contact surface. They also reduce heat generation, which is crucial for the improvement of biocompatibility properties (23). REFERENCES 7. Magovern GJ Jr, Simpson KA. Extracorporeal membrane oxygenation for adult cardiac support: the Allegheny experience. Ann Thorac Surg. 1999;68(2):655-661. 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