Membrane Oxygenator for Extracorporeal Blood Oxygenation

Extracorporeal blood oxygenation has become an alternative to supply O2 and remove CO2 from the bloodstream, especially when mechanical ventilation provides insufficient oxygenation. The use of a membrane oxygenator offers the advantage of lower airway pressure than a mechanical ventilator to deliver oxygen to the patient’s blood. However, research and development are still needed to find appropriate membrane materials, module configuration, and to optimize hydrodynamic conditions for achieving high efficient gas transfer and excellent biocompatibility of the membrane oxygenator. This review aims to provide a comprehensive description of the basic principle of the membrane oxygenator and its development. It also discusses the role and challenges in the use of membrane oxygenators for extracorporeal oxygenation on respiratory and cardiac failure patients.

Biofilm microbiome in extracorporeal membrane oxygenator catheters

Despite the formation of biofilms on catheters for extracorporeal membrane oxygenation (ECMO), some patients do not show bacteremia. To elucidate the specific linkage between biofilms and bacteremia in patients with ECMO, an improved understanding of the microbial community within catheter biofilms is necessary. Hence, we aimed to evaluate the biofilm microbiome of ECMO catheters from adults with (n = 6) and without (n = 15) bacteremia. The microbiomes of the catheter biofilms were evaluated by profiling the V3 and V4 regions of bacterial 16s rRNA genes using the Illumina MiSeq sequencing platform. In total, 2,548,172 reads, with an average of 121,341 reads per sample, were generated. Although alpha diversity was slightly higher in the non-bacteremic group, the difference was not statistically significant. In addition, there was no difference in beta diversity between the two groups. We found 367 different genera, of which 8 were present in all samples regardless of group; Limnohabitans, Flavobacterium, Delftia, Massilia, Bacillus, Candidatus, Xiphinematobacter, and CL0-1 showed an abundance of more than 1% in the sample. In particular, Arthrobacter, SMB53, Neisseria, Ortrobactrum, Candidatus Rhabdochlamydia, Deefgae, Dyella, Paracoccus, and Pedobacter were highly abundant in the bacteremic group. Network analysis indicated that the microbiome of the bacteremic group was more complex than that of the non-bacteremic group. Flavobacterium and CL0.1, which were abundant in the bacteremic group, were considered important genera because they connected different subnetworks. Biofilm characteristics in ECMO catheters varied according to the presence or absence of bacteremia. There were no significant differences in diversity between the two groups, but there were significant differences in the community composition of the biofilms. The biofilm-associated community was dynamic, with the bacteremic group showing very complex network connections within the microbiome.

Investigations of the characteristics and performance of modified polyethersulfones (PES) as membrane oxygenator

The modification of membrane oxygenators to minimize protein adsorption onto the surface is often accompanied by the loss of membrane performance. This study aims to explore polyethersulfone (PES) as a new material for membrane oxygenator applications and to assess its potentials. Accordingly, different modification techniques are applied to improve surface properties of PES membranes. To achieve this goal, two separate modification methods including incorporation of TiO2 into the membrane matrix as well as grafting polyethylene glycol (PEG) through oxygen plasma treatment are developed and the effects are examined. The results reveal that protein adsorption to the nanocomposite membrane containing 0.50 wt. % TiO2 and the grafted membrane decreased by 47 and 31%, respectively. In terms of performance, permeability and oxygen transfer rate of all modified membranes exceeded 808 GPU and 2.7 × 10−4 mol·m−2·s−1, respectively. Contact angle analysis revealed signs of hydrophilicity enhancement of membranes after modifications. The findings suggest that upon proper modifications, membranes based on PES could be considered as promising candidates for membrane oxygenator applications and deserves further investigations.

Clinical Characteristics and Predictors of In-Hospital Mortality in Patients With Cardiogenic Shock: Results From the RESCUE Registry

Background: In the current era of mechanical circulatory support, limited data are available on prognosis of cardiogenic shock (CS) caused by various diseases. We investigated the characteristics and predictors of in-hospital mortality in Korean patients with CS. Methods: The RESCUE study (Retrospective and Prospective Observational Study to Investigate Clinical Outcomes and Efficacy of Left Ventricular Assist Device for Korean Patients With CS) is a multicenter, retrospective, and prospective registry of patients that presented with CS. Between January 2014 and December 2018, 1247 patients with CS were enrolled from 12 major centers in Korea. The primary outcome was in-hospital mortality. Results: In-hospital mortality rate was 33.6%. The main causes of shock were ischemic heart disease (80.7%), dilated cardiomyopathy (6.1%), myocarditis (3.2%), and nonischemic ventricular arrhythmia (2.5%). Vasopressors were used in 1081 patients (86.7%). The most frequently used vasopressor was dopamine (63.4%) followed by norepinephrine (57.3%). An intraaortic balloon pump was used in 314 patients (25.2%) and extracorporeal membrane oxygenator in 496 patients (39.8%). In multivariable analysis, age ≥70years (odds ratio [OR], 2.73 [95% CI, 1.89–3.94], P <0.001), body mass index <25 kg/m 2 (OR, 1.52 [95% CI, 1.08–2.16], P =0.017), cardiac arrest at presentation (OR, 2.16 [95% CI, 1.44–3.23], P <0.001), vasoactive-inotrope score >80 (OR, 3.55 [95% CI, 2.54–4.95], P <0.001), requiring continuous renal replacement therapy (OR, 4.14 [95% CI, 2.88–5.95], P <0.001), mechanical ventilator (OR, 3.17 [95% CI, 2.16–4.63], P <0.001), intraaortic balloon pump (OR, 1.55 [95% CI, 1.07–2.24], P =0.020), and extracorporeal membrane oxygenator (OR, 1.85 [95% CI, 1.25–2.76], P =0.002) were independent predictors for in-hospital mortality. Conclusions: The in-hospital mortality of patients with CS remains high despite the high utilization of mechanical circulatory support. Age, low body mass index, cardiac arrest at presentation, amount of vasopressor, and advanced organ failure requiring various support devices were poor prognostic factors for in-hospital mortality. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02985008.