Endothelial and Hemodynamic Function in a Large Animal Model in Relation to Different Extracorporeal Membrane Oxygenation Cannulation Strategies and Intra-Aortic Balloon Pumping.

BACKGROUND: The use of simultaneous veno-arterial extracorporeal membrane oxygenation (ECMO) with or without an Intra-Aortic Balloon Pump (IABP) is a widely used tool for mechanical hemodynamic support. Endothelial function, especially in relation to different cannulation techniques, is rarely investigated in the setting of extracorporeal life support (ECLS). In this study, we analyzed endothelial function in relation to hemodynamic and laboratory parameters for central and peripheral ECMO, with or without concomitant IABP support in a large animal model to gain a better understanding of the underlying basic mechanisms. METHODS: In this large animal model, healthy female pigs with preserved ejection fraction were divided into the following groups related to cannulation strategy for ECMO and simultaneous IBAP support: control (no ECMO, no IABP), peripheral ECMO (pECMO), central ECMO (cECMO), pECMO and IABP or cECMO and IABP. During the experimental setting, the blood flow in the ascending aorta, left coronary artery and arteria carotis was measured. Afterwards, endothelial function was investigated after harvesting the right coronary artery, arteria carotis and renal artery. In addition, laboratory markers, such as creatine kinase (CK), creatine kinase muscle-brain (CK-MB), troponin, creatinine and endothelin were analyzed. RESULTS: The blood flow in the ascending aorta and the left coronary artery was significantly lower in all discussed experimental settings compared to the control group. Of note, the cECMO cannulation strategy generated favorable hemodynamic circumstances with higher blood flow in the coronary arteries than pECMO regardless of flow circumstances in the ascending aorta. The concomitant usage of IABP did not result in an improvement of the coronary blood flow, but partially showed a negative impact on the endothelial function of coronary arteries in comparison to the control. These findings correlate to higher CK/CK-MB levels in the setting of cECMO + IABP and pECMO + IABP. CONCLUSIONS: The usage of mechanical circulatory support with concomitant ECMO and IABP in a large animal model might have an influence on the endothelial function of coronary arteries while not improving the coronary artery perfusion in healthy hearts with preserved ejection.

Investigation of the Damage Phenomenology with Dependence on the Macroporosity and Microporosity of Porous Freeze Foams.

Freeze Foams are cellular, ceramic structures with hierarchical pore structures that are manufactured using the direct foaming process. By tailoring their morphology and strength, these foam structures are able to cover a wide range of application. Earlier works identified that pore-forming influencing factors (water and air content, suspension temperature, as well as pressure reduction rate) dictate the constitution on a macroscopic and microscopic scale. Therefore, the ability to manufacture foams whose properties align with the component requirements would be an important step in advancing towards a widespread application of these promising materials. With this goal in mind, the correlation between the pore-forming influencing factors and the resulting mechanical properties was quantified. Foams with independently adjustable porosities were produced at the micro and macro scales and evaluated according to their material failure behavior under compressive loads. As a result, foams with determined macroporosities between 38 and 62%, microporosities between 25 and 42%, and compression strengths between 1 and 7 MPa with different material failure characteristics were manufactured and systematically investigated.

Tailoring of Hierarchical Porous Freeze Foam Structures.

Freeze foaming is a method to manufacture cellular ceramic scaffolds with a hierarchical porous structure. These so-called freeze foams are predestined for the use as bone replacement material because of their internal bone-like structure and biocompatibility. On the one hand, they consist of macrostructural foam cells which are formed by the expansion of gas inside the starting suspension. On the other hand, a porous microstructure inside the foam struts is formed during freezing and subsequent freeze drying of the foamed suspension. The aim of this work is to investigate for the first time the formation of macrostructure and microstructure separately depending on the composition of the suspension and the pressure reduction rate, by means of appropriate characterization methods for the different pore size ranges. Moreover, the foaming behavior itself was characterized by in-situ radiographical and computed tomography (CT) evaluation. As a result, it could be shown that it is possible to tune the macro- and microstructure separately with porosities of 49-74% related to the foam cells and 10-37% inside the struts.

Adhesion Studies during Generative Hybridization of Textile-Reinforced Thermoplastic Composites via Additive Manufacturing.

Generative hybridization enables the efficient production of lightweight structures by combining classic manufacturing processes with additive manufacturing technologies. This type of functionalization process allows components with high geometric complexity and high mechanical properties to be produced efficiently in small series without the need for additional molds. In this study, hybrid specimens were generated by additively depositing PA6 (polyamide 6) via fused layer modeling (FLM) onto continuous woven fiber GF/PA6 (glass fiber/polyamide 6) flat preforms. Specifically, the effects of surface pre-treatment and process-induced surface interactions were investigated using optical microscopy for contact angle measurements as well as laser profilometry and thermal analytics. The bonding characteristic at the interface was evaluated via quasi-static tensile pull-off tests. Results indicate that both the bond strength and corresponding failure type vary with pre-treatment settings and process parameters during generative hybridization. It is shown that both the base substrate temperature and the FLM nozzle distance have a significant influence on the adhesive tensile strength. In particular, it can be seen that surface activation by plasma can significantly improve the specific adhesion in generative hybridization.

Levosimendan Reduces Mortality and Low Cardiac Output Syndrome in Cardiac Surgery.

BACKGROUND: There has been conflicting evidence concerning the effect of levosimendan on clinical outcomes in patients undergoing cardiac surgery. Therefore, we performed a systematic review and conducted this meta-analysis to provide evidence for/against the administration of levosimendan in cardiac surgery patients. METHODS: We performed a meta-analysis from literature search in PubMed, EMBASE, and Cochrane Library. Only randomized controlled trials comparing the administration of levosimendan in cardiac surgery patients with a control group (other inotrope, standard therapy/placebo, or an intra-aortic balloon pump) were included. In addition, at least one clinical outcome had to be mentioned: mortality, myocardial infarction, low cardiac output syndrome (LCOS), acute kidney injury, renal replacement therapy, atrial fibrillation, prolonged inotropic support, length of intensive care unit, and hospital stay. The pooled treatment effects (odds ratio [OR], 95% confidence intervals [CI]) were assessed using a fixed or random effects model. RESULTS: The literature search retrieved 27 randomized, controlled trials involving a total of 3,198 patients. Levosimendan led to a significant reduction in mortality (OR: 0.67; 95% CI: 0.49-0.91; p = 0.0087). Furthermore, the incidence of LCOS (OR: 0.56, 95% CI: 0.42-0.75; p < 0.0001), acute kidney injury (OR: 0.63; 95% CI: 0.46-0.86; p = 0.0039), and renal replacement therapy (OR: 0.70; 95% CI: 0.50-0.98; p = 0.0332) was significantly decreased in the levosimendan group. CONCLUSION: Our meta-analysis suggests beneficial effects for the prophylactic use of levosimendan in patients with severely impaired left ventricular function undergoing cardiac surgery. The administration of levosimendan was associated with a reduced mortality, less LCOS, and restored adequate organ perfusion reflected in less acute kidney injury.

Characteristics and outcomes of patients with right-sided endocarditis undergoing cardiac surgery.

BACKGROUND: There has been an increasing incidence of right-sided infective endocarditis (RSIE) due to the global rise of intravenous drug use (IVDU) and an increasing number of implantable cardiac electronic devices and central venous catheters. Our aim was to investigate differences in the clinical presentation, microbiological findings and prognosis of patients undergoing surgery for RSIE compared to left-sided infective endocarditis (LSIE). METHODS: Relevant clinical data of all 432 consecutive patients undergoing valve surgery for infective endocarditis (IE) at our institution between January 2009 and December 2018 were retrospectively analyzed. Acquired data included patients' demographic and preoperative comorbidities, manifestation of IE according to the recently modified Duke Criteria, perioperative data and relevant clinical outcomes. RESULTS: A total of 403 patients (93.3%) underwent surgery for LSIE and twenty-nine patients (6.7%) for RSIE. Eleven patients with RSIE (37.9%) showed a concomitant left-sided infection. Compared to LSIE, RSIE patients were significantly younger [47.5 (40.4-69.3) vs. 65.1 (53.7-74.6); P=0.008] and presented with less comorbidities such as hypertension (41.4% vs. 65.3%; P=0.010) and coronary artery disease (6.9% vs. 29.0%; P=0.010). Rates of IVDU (34.5% vs. 4.5%; P<0.001), human immunodeficiency virus (HIV) (10.3% vs. 1.7%; P=0.023) and hepatitis C virus (HCV) infection (24.1% vs. 5.2%; P=0.001) were greater in RSIE. The proportion of Staphylococcus aureus IE was significantly higher in RSIE compared to LSIE (37.9% vs. 21.1%; P=0.035). 30-day mortality was 6.9% after surgery for RSIE compared to 14.6% after operation for LSIE (P=0.372). CONCLUSIONS: Patients undergoing surgery for RSIE compared to LSIE presented with a higher rate of pulmonary septic emboli, more Staphylococcus aureus infections and larger vegetations. Larger multicenter prospective trials are needed to provide more reliable data on the clinical profile of these patients, in order to determine optimal surgical management.

The role of extracorporeal life support in the management with severe idiopathic pulmonary artery hypertension undergoing lung transplantation: are those patients referred too late?

BACKGROUND: Idiopathic pulmonary artery hypertension (iPAH) is a relatively minor indication for lung transplantation (LTx) with comparatively poorer outcomes. Extracorporeal life support (ECLS) in various forms is increasingly being used in the management of this entity. However, the data and experience with this therapy remains limited. We evaluated the role of ECLS in the management of severe iPAH patients as a bridge to LTx as well as post LTx support. METHODS: A retrospective analysis of iPAH patients that received LTx between January 2007 and May 2014 was performed. Early- and mid-term outcomes were analyzed for this patient cohort. Also, early and mid-term outcomes after LTx were compared to the control group of patients with other diagnoses using unadjusted analysis and 1:3 propensity score matching. RESULTS: Of 321 LTx performed during the study period in our centre 15 patients had iPAH as a cause of end-stage lung disease. Four iPAH (27%) patients were bridged to LTx utilizing ECLS in the form of veno-arterial ECMO and extra-corporeal CO2 removal device, whereas 9 patients (60%) required ECLS support for primary graft dysfunction (PGD) after surgery. Patients with iPAH required more frequently on-pump LTx, both pre and post LTx ECLS, and had significantly lower pO2/FiO2 ratio at 24, 48 and 72 hours after LTx. Also iPAH patients had significantly longer ICU and hospital stay. Whereas the incidence of postoperative bronchiolitis obliterans syndrome (BOS) and rejection was comparable to the control group, overall cumulative survival with up to 6 years follow-up was significantly poorer in the iPAH group. After propensity score matching, the results in terms of postoperative outcomes remained as in the unadjusted analysis. CONCLUSIONS: ECLS is an essential tool in the armamentarium of any lung transplant program treating iPAH with a potential of bridge patients to transplantation and to overcome graft dysfunction after LTx. Despite utilization of ECLS in the management of iPAH, the outcomes in terms of primary graft failure and survival remain poor compared to patients with other diagnoses.

Monitoring of adult patient on venoarterial extracorporeal membrane oxygenation in intensive care medicine.

Nowadays high-tech medical assist device therapy is a crucial part of intensive care medicine. Especially, management of circulatory assist device systems poses an increasing challenge for intensive care medicine. So far, autonomous recommendations for monitoring of extracorporeal life support systems in the form of guidelines or position papers are lacking. The purpose of this paper was to present an orientation guide on this important topic.

Investigation of the Foam Development Stages by Non-Destructive Testing Technology Using the Freeze Foaming Process.

With a novel Freeze Foaming method, it is possible to manufacture porous cellular components whose structure and composition also enables them for application as artificial bones, among others. To tune the foam properties to our needs, we have to understand the principles of the foaming process and how the relevant process parameters and the foam's structure are linked. Using in situ analysis methods, like X-ray microcomputed tomography (µCT), the foam structure and its development can be observed and correlated to its properties. For this purpose, a device was designed at the Institute of Lightweight Engineering and Polymer Technology (ILK). Due to varying suspension temperature and the rate of pressure decrease it was possible to analyze the foam's developmental stages for the first time. After successfully identifying the mechanism of foam creation and cell structure formation, process routes for tailored foams can be developed in future.

Impact of ascending aortic, hemiarch and arch repair on early and long-term outcomes in patients with Stanford A acute aortic dissection.

BACKGROUND:: Stanford A acute aortic dissection (AAD) is a life-threatening emergency associated with major morbidity and mortality. The aim of this study was to compare outcomes of three different surgical approaches in patients with Stanford A AAD. METHODS:: From January 2006 to March 2015 a total of 240 consecutive patients with diagnosed Stanford A AAD underwent elective, isolated surgical aortic repair in our centre. Patients were divided into three groups according to the extent of surgical repair: isolated replacement of the ascending aorta, hemiarch replacement and total arch replacement. Patients were followed up for up to 9 years. After univariate analysis multinomial logistic regression was performed for subgroup analysis. Baseline characteristics and endpoints as well as long-term survival were analysed. RESULTS:: There were no statistically significant differences among the three groups in terms of demographics and preoperative baseline and clinical characteristics. Incidence of in-hospital stroke ( p = 0.034), need for reopening due to bleeding ( p = 0.031) and in-hospital mortality ( p = 0.017) increased significantly with the extent of the surgical approach. There was no statistical difference in terms of long-term survival ( p = 0.166) among the three groups. Applying multinomial logistic regression for subgroup analysis significantly higher odds for stroke ( p = 0.023), reopening for bleeding ( p = 0.010) and in-hospital mortality ( p = 0.009) for the arch surgery group in comparison to the ascending aorta surgery group as well as significantly higher odds for stroke ( p = 0.029) for the total arch surgery group in comparison to the hemiarch surgery group were identified. CONCLUSIONS:: With Stanford A AAD the incidence of perioperative complications increased significantly with the extent of the surgical approach. Subgroup analysis and long-term follow up in patients undergoing isolated ascending or hemiarch surgery showed a lower incidence of cerebrovascular events compared with surgery for total arch replacement.

Impact of age on early outcomes and long-term survival of patients undergoing aortic repair with Stanford A dissection.

OBJECTIVES: Stanford A acute aortic dissection (AAD) is a life-threatening emergency, typically occurring in older patients and requiring immediate surgical repair. The aim of this study was to evaluate early outcome and short- and long-term survival of patients under and above 65 years of age. METHODS: Two hundred and forty patients with Stanford A AAD underwent aortic surgical repair from January 2006 to April 2015 in our center. After statistical analysis and logistic regression analysis, Kaplan-Meier survival estimation was performed, with up to 9-year follow-up, comprising patients under and above 65 years of age. RESULTS: The proportion of patients above 65 years of age suffering from Stanford A AAD was 50% (n=120). The group of patients above 65 years of age compared to the group under 65 years of age showed statistically significant differences in terms of higher odds ratios (OR) for hypertension (p=0.012), peripheral vascular disease (p=0.026) and tachyarrhythmia absoluta (p=0.004). Patients over 65 years of age also showed significantly poorer short- and long-term survival. Our subgroup analysis revealed that male patients (Breslow p=0.001, Log-Rank p=0.001) and patients suffering with hypertension (Breslow p=0.003, Log-Rank p=0.001) were reasonable for these results whereas younger and older female patients showed similar short- and long-term outcome (Breslow p=0.926, Log-Rank p=0.724). After stratifying all patients into 4 age groups (<45; 55-65; 65-75; >75years), short-term survival of the patients appeared to be significantly poorer with increasing age (Breslow p=0.026, Log-Rank p=0.008) whereas long-term survival of patients free from cerebrovascular events (Breslow p=0.0494, Log-Rank p=0.489) remained similar. CONCLUSIONS: All patients referred to our hospital for repair of Stanford A AAD with higher age had poorer short- and long-term survival, caused by male patients and patients suffering from hypertension, whereas survival of women and survival free from cerebrovascular events of the entire patient cohort was similar, irrespective of age.

Effect of preoperative low serum albumin on postoperative complications and early mortality in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Patients undergoing transcatheter aortic valve replacement (TAVR) are mostly elderly patients with substantial comorbidities. Established risk scores are not validated for TAVR and collectives with elderly patients making periprocedural risk stratification difficult. Serum albumin is known to be an indicator for malnutrition and frailty and is simple to measure, independent of physician's bias. Using serum albumin as a preoperative marker for postoperative complications might help estimating morbidity and mortality of these patients. METHODS: A total of 457 patients with severe symptomatic aortic stenosis undergoing TAVR at our institution in a period from January 2014 to December 2015 were included in this retrospective study. Baseline characteristics as well as preoperative laboratory parameters were registered. Postoperative morbidity and 30-day mortality were analyzed as primary end points. Enrolled patients with preoperative low serum albumin (<3.5 g/dL) were compared with those revealing normal serum albumin (≥3.5 g/dL). RESULTS: Among 457 patients, 51 (11%) presented pre-procedural low serum albumin and 406 (89%) had normal serum albumin. Patients' mean age was 81±6 years and 50% of them were male. Postoperative complications such as requirement of blood transfusions (63% versus 33%, P<0.001), infection (53% versus 24%, P<0.001), acute kidney injury (41% versus 19%, P=0.001) and 30-day mortality (10% versus 3%, P=0.045) showed significant differences between preoperative low and normal albumin groups. CONCLUSIONS: Preoperative low serum albumin might be an indicator for higher morbidity and mortality in patients undergoing TAVR.

Social cognitive aspects of the participation in workplace health promotion as revealed by the theory of planned behavior.

Health-promoting efforts strongly depend on individual cognitions such as attitudes as well as social cognitive aspects of the work environment such as leadership and support. Using the theory of planned behavior (TPB) as a theoretical frame, participation behavior of employees in courses offered by the workplace health promotion (WHP) program of the German Armed Forces was investigated. Social cognitive aspects of the work environment, such as leadership behaviors by setting an example or optimizing organization of work, were included in the TPB components of subjective norm and perceived behavioral control, which allowed for an investigation of the specific effects of leadership on WHP participation. A survey study with N=1385 members of the German Armed Forces was conducted in 2015 in Germany. Results showed that perceived behavioral control and attitudes towards WHP were the strongest predictors for WHP participation. While subjective norm was positively related to attitudes, it had a slightly negative effect on intention to participate in WHP activities. These findings suggest that the most effective way for leadership to increase WHP participation is to enhance perceived behavioral control. Quite contrary, creating a positive subjective norm regarding WHP participation may even result in psychological reactance.