Extracorporeal Membrane Oxygenation Blood Research Articles

The Influence of Different ECMO Cannulation Site and Blood Perfusion Conditions on the Aortic Hemodynamics: A Computational Fluid Dynamic Model

Extracorporeal Membrane Oxygenation (ECMO) is a medical device used to support patients with severe cardiac and/or respiratory failure. It is being used more frequently to offer percutaneous mechanical circulatory support, even though the intricate interactions between ECMO and the failing heart, as well as its impact on hemodynamics and perfusion, are not yet fully understood. Within the two main types of ECMO support (the veno-venous ECMO (VV-ECMO), which is used to support only the lungs) and the veno-arterial ECMO (VA-ECMO), which is used to support the lungs and heart), consideration is given solely to the second approach. Indeed, this study focuses on the impact of different ECMO cannulation site and blood perfusion conditions on the aortic hemodynamics and organ perfusion in VA-ECMO. Using computed tomography (CT) images, we reconstructed specific aortic models based on clinical cannula configurations and placements. A detailed cannula-aorta integration model was developed to simulate the VA-ECMO blood supply environment. Employing computational fluid dynamics (CFD), we analyzed how varying ECMO perfusion levels and ECMO cannulation sites affect flow characteristics. This study provides insights into optimizing ECMO therapy by understanding its effects on blood flow and potential damage to blood and organs.

Effects of different VV ECMO blood flow rates on lung perfusion assessment by hypertonic saline bolus-based electrical impedance tomography

ObjectiveOur study aimed to investigate the effects of different extracorporeal membrane oxygenation (ECMO) blood flow rates on lung perfusion assessment using the saline bolus-based electrical impedance tomography (EIT) technique in patients on veno-venous (VV) ECMO.MethodsIn this single-centered prospective physiological study, patients on VV ECMO who met the ECMO weaning criteria were assessed for lung perfusion using saline bolus-based EIT at various ECMO blood flow rates (gradually decreased from 4.5 L/min to 3.5 L/min, 2.5 L/min, 1.5 L/min, and finally to 0 L/min). Lung perfusion distribution, dead space, shunt, ventilation/perfusion matching, and recirculation fraction at different flow rates were compared.ResultsFifteen patients were included. As the ECMO blood flow rate decreased from 4.5 L/min to 0 L/min, the recirculation fraction decreased significantly. The main EIT-based findings were as follows. (1) Median lung perfusion significantly increased in region-of-interest (ROI) 2 and the ventral region [38.21 (34.93–42.16)% to 41.29 (35.32–43.75)%, p = 0.003, and 48.86 (45.53–58.96)% to 54.12 (45.07–61.16)%, p = 0.037, respectively], whereas it significantly decreased in ROI 4 and the dorsal region [7.87 (5.42–9.78)% to 6.08 (5.27–9.34)%, p = 0.049, and 51.14 (41.04–54.47)% to 45.88 (38.84–54.93)%, p = 0.037, respectively]. (2) Dead space significantly decreased, and ventilation/perfusion matching significantly increased in both the ventral and global regions. (3) No significant variations were observed in regional and global shunt.ConclusionsDuring VV ECMO, the ECMO blood flow rate, closely linked to recirculation fraction, could affect the accuracy of lung perfusion assessment using hypertonic saline bolus-based EIT.

Immediate Clinical Complications Occurring During Membrane Change in Patients on Veno-Venous Extracorporeal Membrane Oxygenation.

The clinical tolerance of extracorporeal membrane oxygenation (ECMO) membrane changes in acute respiratory distress syndrome (ARDS) patients under veno-venous ECMO (VV-ECMO) has not been reported. The aim of this study was to describe the tolerance of membrane change. Patients requiring VV-ECMO were retrospectively included between March 2020 and May 2022. In case of membrane dysfunction or an increase in hemolysis markers or an alteration in gas exchange, a membrane change was performed. The primary outcome was a composite measure defined as the occurrence of at least one of the following events within 1 hour of membrane change: severe hypoxemia, hemodynamic collapse, bradycardia, arrhythmia, cardiac arrest, and death. During the study period, 70 patients required a VV-ECMO, 29 (41%) of whom died. Thirty-two patients required a membrane change for a total of 56 changes. The primary outcome occurred for 33 (59%) changes. Arterial desaturation <80% occurred for all complicated membrane changes and cardiac arrest concerned nine changes (16%). Low tidal volume (VT), respiratory system compliance (Crs), PaO2, and high ECMO blood flow (QECMO) were associated with poor tolerance of membrane change. Threshold values of 130 ml for VT, 9.3 cm H2O for Crs, 72 mm Hg for PaO2, and 3.65 L/minute for QECMO best determined the risk of poor tolerance of membrane change.

Physiologic Effects of Extracorporeal Membrane Oxygenation in Patients with Severe Acute Respiratory Distress Syndrome.

Rationale: Blood flow rate affects mixed venous oxygenation (SvO2) during venovenous extracorporeal membrane oxygenation (ECMO), with possible effects on the pulmonary circulation and the right heart function. Objectives: To describe the physiologic effects of different levels of SvO2 obtained by changing ECMO blood flow in patients with severe acute respiratory distress syndrome receiving ECMO and controlled mechanical ventilation. Methods: Low (SvO2 target, 70-75%), intermediate (SvO2 target, 75-80%), and high (SvO2 target, >80%) ECMO blood flows were applied for 30 minutes in random order in 20 patients. Mechanical ventilation settings were left unchanged. The hemodynamic and pulmonary effects were assessed with pulmonary artery catheter and electrical impedance tomography. Measurements and Main Results: Cardiac output decreased from low to intermediate and to high blood flow/SvO2 (9.2 [6.2-10.9] vs. 8.3 [5.9-9.8] vs. 7.9 [6.5-9.1] L/min; P = 0.014), as well as mean pulmonary artery pressure (34 ± 6 vs. 31 ± 6 vs. 30 ± 5 mm Hg; P < 0.001) and right ventricular stroke work index (14.2 ± 4.4 vs. 12.2 ± 3.6 vs. 11.4 ± 3.2 g × m/beat/m2; P = 0.002). Cardiac output was inversely correlated with mixed venous and arterial Po2 values (R2 = 0.257; P = 0.031; and R2 = 0.324; P = 0.05). Pulmonary artery pressure was correlated with decreasing mixed venous Po2 (R2 = 0.29; P < 0.001) and with increasing cardiac output (R2 = 0.378; P < 0.007). Measures of [Formula: see text]/[Formula: see text] mismatch did not differ between the three steps. Conclusions: In patients with severe acute respiratory distress syndrome, increased ECMO blood flow rate resulting in higher SvO2 decreases pulmonary artery pressure, cardiac output, and right heart workload.

Risk factors for cannula-associated arterial thrombosis following extracorporeal membrane oxygenation support: a retrospective study.

Hemostatic dysfunction during extracorporeal membrane oxygenation (ECMO) due to blood-circuit interaction and the consequences of shear stress imposed by flow rates lead to rapid coagulation cascade and thrombus formation in the ECMO system and blood vessels. We aimed to identify the incidence and risk factors for cannula-associated arterial thrombosis (CaAT) post-decannulation. A retrospective study of patients undergoing arterial cannula removal following ECMO was performed. We evaluated the incidence of CaAT and compared the characteristics, ECMO machine parameters, cannula sizes, number of blood products transfused during ECMO, and daily hemostasis parameters in patients with and without CaAT. Multivariate analysis identified the risk factors for CaAT. Forty-seven patients requiring venoarterial ECMO (VA-ECMO) or hybrid methods were recruited for thrombosis screening. The median Sequential Organ Failure Assessment score was 11 (interquartile range, 8-13). CaAT occurred in 29 patients (61.7%), with thrombosis in the superficial femoral artery accounting for 51.7% of cases. The rate of limb ischemia complications in the CaAT group was 17.2%. Multivariate analysis determined that the ECMO flow rate-body surface area (BSA) ratio (100 ml/min/m2) was an independent factor for CaAT, with an odds ratio of 0.79 (95% confidence interval, 0.66-0.95; P=0.014). We found that the incidence of CaAT was 61.7% following successful decannulation from VA-ECMO or hybrid modes, and the ECMO flow rate-BSA ratio was an independent risk factor for CaAT. We suggest screening for arterial thrombosis following VA-ECMO, and further research is needed to determine the risks and benefits of such screening.

Effects of adding the second drainage cannula in severely hypoxemic patients supported with VV ECMO due to COVID-19-associated ARDS.

Extracorporeal membrane oxygenation (ECMO) is a recognized method of support in patients with severe and refractory acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection. While veno-venous (VV) ECMO is the most common type, some patients with severe hypoxemia may require modifications to the ECMO circuit. In this study, we aimed to investigate the effects of adding a second drainage cannula to the circuit in patients with refractory hypoxemia, on their gas exchange, mechanical ventilation, ECMO settings, and clinical outcomes. We conducted an observational retrospective study based on a single-center institutional registry including all consecutive cases of COVID-19 patients requiring ECMO admitted to the Centre of Extracorporeal Therapies in Warsaw between March 1, 2020 and March 1, 2022. We selected patients who had an additional drainage cannula inserted. Changes in ECMO and ventilator settings, blood oxygenation, and hemodynamic parameters, as well as clinical outcomes were assessed. Of 138 VV ECMO patients, 12 (9%) patients met the inclusion criteria. Ten patients (83%) were men, and mean age was 42.2 ± 6.8. An addition of drainage cannula resulted in a significant raise in ECMO blood flow (4.77 ± 0.44 to 5.94 ± 0.81 [L/min]; p = 0.001), and the ratio of ECMO blood flow to ECMO pump rotations per minute (RPM), whereas the raise in ECMO RPM alone was not statistically significant (3432 ± 258 to 3673 ± 340 [1/min]; p = 0.064). We observed a significant drop in ventilator FiO2 and a raise in PaO2 to FiO2 ratio, while blood lactates did not change significantly. Nine patients died in hospital, one was referred to lung transplantation center, two were discharged uneventfully. The use of an additional drainage cannula in severe ARDS associated with COVID-19 allows for an increased ECMO blood flow and improved oxygenation. However, we observed no further improvement in lung-protective ventilation and poor survival.

High- versus Low-Flow Extracorporeal Respiratory Support in Experimental Hypoxemic Acute Lung Injury.

Rationale: In the EOLIA (ECMO to Rescue Lung Injury in Severe ARDS) trial, oxygenation was similar between intervention and conventional groups, whereas [Formula: see text]e was reduced in the intervention group. Comparable reductions in ventilation intensity are theoretically possible with low-flow extracorporeal CO2 removal (ECCO2R), provided oxygenation remains acceptable. Objectives: To compare the effects of ECCO2R and extracorporeal membrane oxygenation (ECMO) on gas exchange, respiratory mechanics, and hemodynamics in animal models of pulmonary (intratracheal hydrochloric acid) and extrapulmonary (intravenous oleic acid) lung injury. Methods: Twenty-four pigs with moderate to severe hypoxemia (PaO2:FiO2 ⩽ 150 mm Hg) were randomized to ECMO (blood flow 50-60 ml/kg/min), ECCO2R (0.4 L/min), or mechanical ventilation alone. Measurements and Main Results: [Formula: see text]o2, [Formula: see text]co2, gas exchange, hemodynamics, and respiratory mechanics were measured and are presented as 24-hour averages. Oleic acid versus hydrochloric acid showed higher extravascular lung water (1,424 ± 419 vs. 574 ± 195 ml; P < 0.001), worse oxygenation (PaO2:FiO2 = 125 ± 14 vs. 151 ± 11 mm Hg; P < 0.001), but better respiratory mechanics (plateau pressure 27 ± 4 vs. 30 ± 3 cm H2O; P = 0.017). Both models led to acute severe pulmonary hypertension. In both models, ECMO (3.7 ± 0.5 L/min), compared with ECCO2R (0.4 L/min), increased mixed venous oxygen saturation and oxygenation, and improved hemodynamics (cardiac output = 6.0 ± 1.4 vs. 5.2 ± 1.4 L/min; P = 0.003). [Formula: see text]o2 and [Formula: see text]co2, irrespective of lung injury model, were lower during ECMO, resulting in lower PaCO2 and [Formula: see text]e but worse respiratory elastance compared with ECCO2R (64 ± 27 vs. 40 ± 8 cm H2O/L; P < 0.001). Conclusions: ECMO was associated with better oxygenation, lower [Formula: see text]o2, and better hemodynamics. ECCO2R may offer a potential alternative to ECMO, but there are concerns regarding its effects on hemodynamics and pulmonary hypertension.

Pressure ulcers after prone positioning in patients undergoing extracorporeal membrane oxygenation: A cross-sectional study.

The combination of prone positioning and extracorporeal membrane oxygenation (ECMO) in patients with acute respiratory distress syndrome (ARDS) is recognized as safe but its use has been limited due to potential complications. To report the prevalence of pressure ulcers and other complications due to prone positioning in adult patients receiving veno-venous ECMO. This cross-sectional study was conducted in a tertiary level intensive care unit (ICU) in Milan (Italy), between January 2015 and December 2019. The study population was critically ill adult patients undergoing veno-venous ECMO. Statistical association between pressure ulcers and the type of body positioning (prone versus supine) was explored fitting a logistic model. In the study period, 114 patients were treated with veno-venous ECMO and 62 (54.4%) patients were placed prone for a total of 130 prone position cycles. ECMO cannulation was performed via femoro-femoral configuration in the majority of patients (82.4%, 94/114). Pressure ulcers developed in 57.0% of patients (95%CI: 44.0%-72.6%), most often arising on the face and the chin (37.1%, 23/62), particularly in those placed prone. The main reason of prone positioning interruption was the decrease of ECMO blood flow (8.1%, 5/62). The fitted model showed no association between body position during ECMO and occurrence of pressure ulcers (OR 1.3, 95%CI: 0.5-3.6, p=.532). Facial pressure ulcers were the most frequent complications of prone positioning. Nurses should plan and implement evidence-based care to prevent such pressure injuries in patients undergoing ECMO. The combination of prone positioning and ECMO shows few life-threating complications. This manoeuvre during ECMO is feasible and safe when performed by experienced ICU staff.

Impact of connecting methods of continuous renal replacement therapy device on patients underwent extracorporeal membrane oxygenation: A retrospectively observational study

ObjectiveThe objective of this study was to compare the safety and efficiency of different extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) connection methods. BackgroundThe number of patients receiving ECMO is increasing, and the fields of application are getting wider. However, patients receiving ECMO are prone to acute kidney injury and fluid overload requiring CRRT. There are few comparative studies of two different systems of connecting CRRT device and ECMO from safety and efficacy perspective. MethodsThis retrospective observational study included patients receiving ECMO in the extracorporeal life support centre of the First Affiliated Hospital of Nanjing Medical University from June, 2015, to December, 2020. Patients were divided into the parallel system group and integrated system group according to the connecting method between ECMO circuit and CRRT line. The outcomes were discharge survival rate, CRRT therapeutic dose completion rate, CRRT catheterisation time, CRRT initiating time, local bleeding at the CRRT catheter site, mean filter life, ECMO circuit thrombosis, ECMO air leakage, or blood leakage due to CRRT. ResultsThirty patients in the parallel system group and 70 patients in the integrated system group were finally included. The discharge survival rate and CRRT therapeutic dose completion rate were not significantly different between the two groups. The parallel system group had significant longer CRRT initiating time (49.0 ± 12.1 min vs. 14.6 ± 2.1 min, P < 0.001) and shorter filter life (11.5 ± 3.2 h vs. 47.3 ± 14.0 h, P < 0.001) than the integrated system group. The occurrence rate of local bleeding was 93.3% in the parallel system group, and there is no bleeding case in the integrated system group. There was no case of ECMO circuit thrombosis from CRRT as well as ECMO air or blood leakage caused by CRRT in either group. ECMO therapy can be adapted by adjusting the position of the CRRT outlet in the integrated system. ConclusionsConnecting CRRT and ECMO as an integrated system might accelerate CRRT initiation, avoid local bleeding, and prolong filter life compared to the parallel system. The chance of developing CRRT-related ECMO circuit leak and thrombosis is manageable.

Effects of changes in veno-venous extracorporeal membrane oxygenation blood flow on the measurement of intrathoracic blood volume and extravascular lung water index: a prospective interventional study

In severe acute respiratory distress syndrome (ARDS), veno-venous extracorporeal membrane oxygenation (V-V ECMO) has been proposed as a therapeutic strategy to possibly reduce mortality. Transpulmonary thermodilution (TPTD) enables monitoring of the extravascular lung water index (EVLWI) and cardiac preload parameters such as intrathoracic blood volume index (ITBVI) in patients with ARDS, but it is not generally recommended during V-V ECMO. We hypothesized that the amount of extracorporeal blood flow (ECBF) influences the calculation of EVLWI and ITBVI due to recirculation of indicator, which affects the measurement of the mean transit time (MTt), the time between injection and passing of half the indicator, as well as downslope time (DSt), the exponential washout of the indicator. EVLWI and ITBVI were measured in 20 patients with severe ARDS managed with V-V ECMO at ECBF rates from 6 to 4 and 2 l/min with TPTD. MTt and DSt significantly decreased when ECBF was reduced, resulting in a decreased EVLWI (26.1 [22.8–33.8] ml/kg at 6 l/min ECBF vs 22.4 [15.3–31.6] ml/kg at 4 l/min ECBF, p < 0.001; and 13.2 [11.8–18.8] ml/kg at 2 l/min ECBF, p < 0.001) and increased ITBVI (840 [753–1062] ml/m2 at 6 l/min ECBF vs 886 [658–979] ml/m2 at 4 l/min ECBF, p < 0.001; and 955 [817–1140] ml/m2 at 2 l/min ECBF, p < 0.001). In patients with severe ARDS managed with V-V ECMO, increasing ECBF alters the thermodilution curve, resulting in unreliable measurements of EVLWI and ITBVI. German Clinical Trials Register (DRKS00021050). Registered 14/08/2018. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021050

Extracorporeal membrane oxygenation circuits in parallel for refractory hypoxemia in patients with COVID-19

ObjectivesRefractory hypoxemia can occur in patients with acute respiratory distress syndrome from COVID-19 despite support with venovenous (VV) extracorporeal membrane oxygenation (ECMO). Parallel ECMO circuits can be used to increase physiologic support. We report our clinical experience using ECMO circuits in parallel for select patients with persistent severe hypoxemia despite the use of a single ECMO circuit. MethodsWe performed a retrospective cohort study of all patients with COVID–19-related acute respiratory distress syndrome who received VV-ECMO with an additional circuit in parallel at Vanderbilt University Medical Center between March 1, 2020, and March 1, 2022. We report demographic characteristics and clinical characteristics including ECMO settings, mechanical ventilator settings, use of adjunctive therapies, and arterial blood gas results after initial cannulation, before and after receipt of a second ECMO circuit in parallel, and before removal of the circuit in parallel, and outcomes. ResultsOf 84 patients with COVID-19 who received VV-ECMO during the study period, 22 patients (26.2%) received a circuit in parallel. The median duration of ECMO was 40.0 days (interquartile range, 31.6-53.1 days), of which 19.0 days (interquartile range, 13.0-33.0 days) were spent with a circuit in parallel. Of the 22 patients who received a circuit in parallel, 16 (72.7%) survived to hospital discharge and 6 (27.3%) died before discharge. ConclusionsIn select patients, the additional use of an ECMO circuit in parallel can increase ECMO blood flow and improve oxygenation while allowing for lung-protective mechanical ventilation and excellent outcomes.

A Novel Mock Circuit to Test Full-Flow Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) has become an important therapeutic approach in the COVID-19 pandemic. The development and research in this field strongly relies on animal models; however, efforts are being made to find alternatives. In this work, we present a new mock circuit for ECMO that allows measurements of the oxygen transfer rate of a membrane lung at full ECMO blood flow. The mock utilizes a large reservoir of heparinized porcine blood to measure the oxygen transfer rate of the membrane lung in a single passage. The oxygen transfer rate is calculated from blood flow, hemoglobin value, venous saturation, and post-membrane arterial oxygen pressure. Before the next measuring sequence, the blood is regenerated to a venous condition with a sweep gas of nitrogen and carbon dioxide. The presented mock was applied to investigate the effect of a recirculation loop on the oxygen transfer rate of an ECMO setup. The recirculation loop caused a significant increase in post-membrane arterial oxygen pressure (paO2). The effect was strongest for the highest recirculation flow. This was attributed to a smaller boundary layer on gas fibers due to the increased blood velocity. However, the increase in paO2 did not translate to significant increases in the oxygen transfer rate because of the minor significance of physically dissolved oxygen for gas transfer. In conclusion, our results regarding a new ECMO mock setup demonstrate that recirculation loops can improve ECMO performance, but not enough to be clinically relevant.

Effect of different connection schemes of continuous renal replacement therapy and extracorporeal membrane oxygenation on arterial and venous pressure: an in vitro and in vivo study

To investigate the effects of different connection schemes of continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO) on arterial pressure (PA), venous pressure (PV), and transmembrane pressure (TMP), and to provide a theoretical basis for choosing a suitable connection scheme. (1) In vitro study: the different connection schemes of CRRT and ECMO were simulated and divided into 6 schemes according to the connection between CRRT and ECMO circuits at different positions. Scheme A: connected to the front and back points of the oxygenator; scheme B: connected to the points behind and in front of the oxygenator; scheme C: connected to the points in front of the oxygenator and in front of the centrifugal pump; scheme D: connected to the points behind the oxygenator and in front of the centrifugal pump; scheme E: connected to the points in front of the oxygenator and the return catheter; scheme F: connected to the points after the oxygenator and the return catheter. Each set of ECMO circuits was measured 5 times under each connection scheme and different flow rates (2, 3, 4, 5, 5.5 L/min). Six ECMO circuits for a total of 30 measurements, and the PA, PV, and TMP of the 6 schemes were compared. (2) In vivo study: the patients who were treated with ECMO combined with CRRT in the department of critical care medicine of the First Affiliated Hospital of Wannan Medical College from August 2017 to August 2021 changed the connection scheme due to high PA or PV (from scheme A or B to scheme E or F) were retrospectively analyzed. The changes of PA and PV before and after changing the scheme were compared. (1) In vitro study results: there was no significant difference in PA between schemes A and B, C and D, E and F under different ECMO blood flow (2-5.5 L/min). The PA of schemes C and D was the lowest, followed by schemes E and F. PV of scheme B was higher than that of scheme A under different ECMO blood flow (2-5.5 L/min). There was no significant difference in PV between schemes C and D, E and F under high ECMO blood flow (3-5.5 L/min), and the absolute value of PV was lowest in schemes E and F. Compared with schemes A and B [partial PA > 300 mmHg (1 mmHg ≈ 0.133 kPa) at high flow rate], C and D (partial PV > 350 mmHg at high flow rate), schemes E and F were more reasonable connection schemes. TMP was negative in schemes C and D at ECMO blood flow of 5 L/min and 5.5 L/min (mmHg; 5 L/min: scheme C was -29.14±11.42, scheme D was -42.45±15.70; 5.5 L/min: scheme C was -35.75±13.21, scheme D was -41.58±15.42), which indicated the presence of dialysate reverse filtration. Most of the differences in TMP among schemes A, B, E, and F under different ECMO blood flow (2-5.5 L/min) were statistically significant, and the absolute value of mean fluctuation was 9.89-49.55 mmHg, all within the normal range. (2) In vivo study results: a total of 10 patients who changed the connection scheme (from scheme A or B to E or F) due to high PA or PV were enrolled, including 8 males and 2 females; 7 cases of venous-arterial ECMO (VA-ECMO) and 3 cases of venous-venous ECMO (VV-ECMO), all used continuous veno-venous hemodiafiltration (CVVHDF) mode. After changing the scheme, both PA and PV decreased significantly as compared with those before changing [PA (mmHg): 244.00±22.58 vs. 257.20±21.92, PV (mmHg): 257.20±18.43 vs. 326.40±15.41, both P < 0.01], and PV decreased more significantly than PA [difference (mmHg): 69.20±6.55 vs. 13.20±5.45, P < 0.01]. For patients treated with ECMO in combination with CRRT, the scheme of connecting the access line of CRRT to the pre-oxygenator or post-oxygenator and connecting the return line to the point of the return catheter can significantly reduce PA and PV and maintains normal CRRT operation even running high-flow ECMO.

A retrospective analysis of the hemolysis occurrence during extracorporeal membrane oxygenation in a single center.

Extracorporeal membrane oxygenation (ECMO)-associated hemolysis still represents a serious complication. The present study aimed to investigate those predictive factors, such as flow rates, the use of anticoagulants, and circuit connected dialysis, that might play a pivotal role in hemolysis in adult patients. This is a retrospective single-center case series of 35 consecutive adult patients undergoing veno-venous ECMO support at our center between April 2014 and February 2020. Daily plasma-free hemoglobin (pfHb) and haptoglobin (Hpt) levels were chosen as hemolysis markers and they were analyzed along with patients' characteristics, daily laboratory findings, and corresponding ECMO system variables, as well as continuous renal replacement therapy (CRRT) when administered, looking for factors influencing their trends over time. Among the many settings related to the ECMO support, the presence of CRRT connected to the ECMO circuit has been found associated with both higher daily pfHb levels and lower Hpt levels. After correction for potential confounders, hemolysis was ascribable to circuit-related variables, in particular the membrane oxygenation dead space was associated with an Hpt reduction (B = -215.307, p = 0.004). Moreover, a reduction of ECMO blood flow by 1L/min has been associated with a daily Hpt consumption of 93.371mg/dL (p = 0.001). Technical-induced hemolysis during ECMO should be monitored not only when suspected but also during quotidian management and check-ups. While considering the clinical complexity of patients on ECMO support, clinicians should not only be aware of and anticipate possible circuitry malfunctions or inadequate flow settings, but they should also take into account the effects of an ECMO circuit-connected CRRT, as an equally important key factor triggering hemolysis.

Comparative polymyxin B pharmacokinetics in patients receiving extracorporeal membrane oxygenation.

To describe polymyxin B pharmacokinetics in patients receiving veno-venous extracorporeal membrane oxygenation (ECMO) in comparison with critically ill patients without ECMO support and to explore potential covariates that could affect the pharmacokinetics in this group of patients. In 13 critically ill patients on ECMO and in 21 critically ill patients without ECMO support, 6-8 blood samples were collected during 12 h intervals after reaching steady state. Polymyxin B concentration in serum was determined using a previously developed ELISA. Protein binding was assessed by rapid equilibrium dialysis. In 13 critically ill patients on ECMO who received polymyxin B, the median area under the concentration-time curve over 12 h (AUC0-12h) was 48.38 mg/h/L for the total drug and 14.08 mg/h/L for the free drug. The unbound fraction was 0.35. Total body clearance was 1.16 L/h. In non-ECMO patients, the median AUC0-12h was 34.7 mg/h/L and the median CL was 1.76 L/h. The volume of distribution was significantly lower in ECMO patients (19.7 versus 30.4 L, respectively). We found a moderate negative correlation between the ECMO blood flow rate and AUC0-12h, a strong negative correlation between SOFA score and polymyxin B clearance and a moderate correlation between polymyxin B clearance and renal function in ECMO patients. Currently recommended polymyxin B dosage regimens are sufficient for patients receiving ECMO and no dosage increase is required. In our study, polymyxin B exposure was higher in ECMO patients compared with the control group.

Multilayer Scaling of a Biomimetic Microfluidic Oxygenator.

Extracorporeal membrane oxygenation (ECMO) has been advancing rapidly due to a combination of rising rates of acute and chronic lung diseases as well as significant improvements in the safety and efficacy of this therapeutic modality. However, the complexity of the ECMO blood circuit, and challenges with regard to clotting and bleeding, remain as barriers to further expansion of the technology. Recent advances in microfluidic fabrication techniques, devices, and systems present an opportunity to develop new solutions stemming from the ability to precisely maintain critical dimensions such as gas transfer membrane thickness and blood channel geometries, and to control levels of fluid shear within narrow ranges throughout the cartridge. Here, we present a physiologically inspired multilayer microfluidic oxygenator device that mimics physiologic blood flow patterns not only within individual layers but throughout a stacked device. Multiple layers of this microchannel device are integrated with a three-dimensional physiologically inspired distribution manifold that ensures smooth flow throughout the entire stacked device, including the critical entry and exit regions. We then demonstrate blood flows up to 200 ml/min in a multilayer device, with oxygen transfer rates capable of saturating venous blood, the highest of any microfluidic oxygenator, and a maximum blood flow rate of 480 ml/min in an eight-layer device, higher than any yet reported in a microfluidic device. Hemocompatibility and large animal studies utilizing these prototype devices are planned.Supplemental Visual , http://links.lww.com/ASAIO/A769.

Exploring the association of two oxygenators in parallel or in series during respiratory support using extracorporeal membrane oxygenation.

To characterize the pressures, resistances, oxygenation, and decarboxylation efficacy of two oxygenators associated in series or in parallel during venous-venous extracorporeal membrane oxygenation support. Using the results of a swine severe respiratory failure associated with multiple organ dysfunction venous-venous extracorporeal membrane oxygenation support model and mathematical modeling, we explored the effects on oxygenation, decarboxylation and circuit pressures of in-parallel and in-series associations of oxygenators. Five animals with a median weight of 80kg were tested. Both configurations increased the oxygen partial pressure after the oxygenators. The return cannula oxygen content was also slightly higher, but the impact on systemic oxygenation was minimal using oxygenators with a high rated flow (~ 7L/minute). Both configurations significantly reduced the systemic carbon dioxide partial pressure. As the extracorporeal membrane oxygenation blood flow increased, the oxygenator resistance decreased initially with a further increase with higher blood flows but with a small clinical impact. Association of oxygenators in parallel or in series during venous-venous extracorporeal membrane oxygenation support provides a modest increase in carbon dioxide partial pressure removal with a slight improvement in oxygenation. The effect of oxygenator associations on extracorporeal circuit pressures is minimal.

Transpulmonary thermodilution in patients treated with veno-venous extracorporeal membrane oxygenation

BackgroundWe tested the effect of different blood flow levels in the extracorporeal circuit on the measurements of cardiac stroke volume (SV), global end-diastolic volume index (GEDVI) and extravascular lung water index derived from transpulmonary thermodilution (TPTD) in 20 patients with severe acute respiratory distress syndrome (ARDS) treated with veno-venous extracorporeal membrane oxygenation (ECMO).MethodsComparative SV measurements with transesophageal echocardiography and TPTD were performed at least 5 times during the treatment of the patients. The data were interpreted with a Bland–Altman analysis corrected for repeated measurements. The interchangeability between both measurement modalities was calculated and the effects of extracorporeal blood flow on SV measurements with TPTD was analysed with a linear mixed effect model. GEDVI and EVLWI measurements were performed immediately before the termination of the ECMO therapy at a blood flow of 6 l/min, 4 l/min and 2 l/min and after the disconnection of the circuit in 7 patients.Results170 pairs of comparative SV measurements were analysed. Average difference between the two modalities (bias) was 0.28 ml with an upper level of agreement of 40 ml and a lower level of agreement of -39 ml within a 95% confidence interval and an overall interchangeability rate between TPTD and Echo of 64%. ECMO blood flow did not influence the mean bias between Echo and TPTD (0.03 ml per l/min of ECMO blood flow; p = 0.992; CI − 6.74 to 6.81). GEDVI measurement was not significantly influenced by the blood flow in the ECMO circuit, whereas EVLWI differed at a blood flow of 6 l/min compared to no ECMO flow (25.9 ± 10.1 vs. 11.0 ± 4.2 ml/kg, p = 0.0035).ConclusionsIrrespectively of an established ECMO therapy, comparative SV measurements with Echo and TPTD are not interchangeable.Such caveats also apply to the interpretation of EVLWI, especially with a high blood flow in the extracorporeal circulation. In such situations, the clinician should rely on other methods of evaluation of the amount of lung oedema with the haemodynamic situation, vasopressor support and cumulative fluid balance in mind.Trial registration: German Clinical Trials Register (DRKS00021050). Registered 03/30/2020https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017237

Context-Responsive Anticoagulation Reduces Complications in Pediatric Extracorporeal Membrane Oxygenation.

Purpose: We sought to determine the impact of a comprehensive, context-responsive anticoagulation and transfusion guideline on bleeding and thrombotic complication rates and blood product utilization during extracorporeal membrane oxygenation (ECMO).Design: Single-center, observational pre- and post-implementation cohort study.Setting: Academic pediatric hospital.Patients: Patients in the PICU, CICU, and NICU receiving ECMO support.Interventions: Program-wide implementation of a context-responsive anticoagulation and transfusion guideline.Measurements: Pre-implementation subjects consisted of all patients receiving ECMO between January 1 and December 31, 2012, and underwent retrospective chart review. Post-implementation subjects consisted of all ECMO patients between September 1, 2013, and December 31, 2014, and underwent prospective data collection. Data collection included standard demographic and admission data, ECMO technical specifications, non-ECMO therapies, coagulation parameters, and blood product administration. A novel grading scale was used to define hemorrhagic complications (major, intermediate, and minor) and major thromboembolic complications.Main Results: Seventy-six ECMO patients were identified: 31 during the pre-implementation period and 45 in the post-implementation period. The overall observed mortality was 33% with no difference between groups. Compared to pre-implementation, the post-implementation group experienced fewer major hemorrhagic and major thrombotic complications and less severe hemorrhagic complications and received less RBC transfusion volume per kg.Conclusions: Use of a context-responsive anticoagulation and transfusion guideline was associated with a reduction in hemorrhagic and thrombotic complications and reduced RBC transfusion requirements. Further evaluation of guideline content, compliance, performance, and sustainability is needed.

Management of intra-abdominal hypertension during ECMO: Total water-assisted colonoscopy as a step-up minimally invasive treatment, and a literature review.

Background and study aims During extracorporeal membrane oxygenation (ECMO), intra-abdominal hypertension (IAH) can impair ECMO venous drainage, reducing its ability to provide an adequate oxygenated blood flow. When medical therapy is ineffective in managing IAH, guidelines recommend a decompressive laparotomy (DL), though the procedure is associated with several complications and poor outcomes. Patients and methods This was a case series of IAH in patients affected with acute respiratory distress syndrome (ARDS) on veno-venous (V-V) ECMO, in whom we performed total water-assisted colonoscopy (t-WAC) to treat IAH. Results In three patients who underwent t-WAC, we report a real-time intra-procedural reduction of IAH, normalization of ECMO blood flow, and a reduction of vasopressors and lactates. t-WAC was performed in the context of evident abdominal compartment syndrome with multiorgan failure, and in one case was performed because of IAH and ECMO impairment. One patient was discharged alive, while the other two died of multiorgan failure, although the cause of death was apparently not secondary to IAH. Conclusions During ECMO, in select cases,T-WAC may represent a first-line non-invasive approach.