Factors associated with hemolysis during extracorporeal membrane oxygenation (ECMO)-Comparison of VA- versus VV ECMO

Extracorporeal Membrane Oxygenation Physiological Factors Influence Pulse Oximetry and Arterial Oxygen Saturation Discrepancies

BACKGROUND

Cannulation strategy, vasopressors, and hemolysis are important physiological factors that influence hemodynamics in extracorporeal membrane oxygenation (ECMO). We hypothesized these factors influence the discrepancy between oxygen saturation measured by pulse oximetry (Spo2) and arterial blood gas (Sao2) in patients on ECMO.

METHODS

We retrospectively analyzed adults (aged ≥18 years) on venoarterial or venovenous ECMO at a tertiary academic ECMO center. Spo2-Sao2 pairs with oxygen saturation ≥70% and measured within 10 minutes were included. Occult hypoxemia was defined as Sao2 ≤88% with a time-matched Spo2 ≥92%. Adjusted linear mixed-effects modeling was used to assess the Spo2-Sao2 discrepancy with preselected demographics and time-matched laboratory variables. Vasopressor use was quantified by vasopressor dose equivalences.

RESULTS

Of 139 venoarterial-ECMO and 88 venovenous-ECMO patients, we examined 20,053 Spo2-Sao2 pairs. The Spo2-Sao2 discrepancy was greater in venovenous-ECMO (1.15%) vs venoarterial-ECMO (-0.35%, P < .001). Overall, 81 patients (35%) experienced occult hypoxemia during ECMO. Occult hypoxemia was more common in venovenous-ECMO (65%) than in venoarterial-ECMO (17%, P < .001). In linear mixed-effects modeling, Spo2 underestimated Sao2 by 9.48% in central vs peripheral venoarterial-ECMO (95% CI, -17.1% to -1.79%; P = .02). Higher vasopressor dose equivalences significantly worsened the Spo2-Sao2 discrepancy (P < .001). In linear mixed-effects modeling, Spo2 overestimated Sao2 by 25.43% in single lumen-cannulated vs double lumen-cannulated venovenous-ECMO (95% CI, 5.27%-45.6%; P = .03). Higher vasopressor dose equivalences and lactate dehydrogenase levels significantly worsened the Spo2-Sao2 discrepancy (P < .001).

CONCLUSIONS

Venovenous-ECMO patients are at higher risk for occult hypoxemia compared with venoarterial-ECMO. A higher vasopressor requirement and different cannulation strategies (central venoarterial-ECMO; single-lumen venovenous-ECMO) were significant factors for clinically significant Spo2-Sao2 discrepancy in both ECMO modes.

Flow capabilities of arterial and drainage cannulae during venoarterial extracorporeal membrane oxygenation: A simulation model

BACKGROUND

Large cannulae can increase cannula-related complications during venoarterial extracorporeal membrane oxygenation (VA ECMO). Conversely, the ability for small cannulae to provide adequate support is poorly understood. Therefore, we aimed to evaluate a range of cannula sizes and VA ECMO flow rates in a simulated patient under various disease states.

METHODS

Arterial cannulae sizes between 13 and 21 Fr and drainage cannula sizes between 21 and 25 Fr were tested in a VA ECMO circuit connected to a mock circulation loop simulating a patient with severe left ventricular failure. Systemic and pulmonary hypertension, physiologically normal, and hypotension were simulated by varying systemic and pulmonary vascular resistances (SVR and PVR, respectively). All cannula combinations were evaluated against all combinations of SVR, PVR, and VA ECMO flow rates.

RESULTS

A 15 Fr arterial cannula combined with a 21 Fr drainage cannula could provide >4 L/min of total flow and a mean arterial pressure of 81.1 mmHg. Changes in SVR produced marked changes to all measured parameters, while changes to PVR had minimal effect. Larger drainage cannulae only increased maximum circuit flow rates when combined with larger arterial cannulae.

CONCLUSION

Smaller cannulae and lower flow rates could sufficiently support the simulated patient under various disease states. We found arterial cannula size and SVR to be key factors in determining the flow-delivering capabilities for any given VA ECMO circuit. Overall, our results challenge the notion that larger cannulae and high flows must be used to achieve adequate ECMO support.

Hemocompatibility Evaluation of a Novel Ambulatory Pulmonary Assist System Using a Lightweight Axial-Flow Pump

The Pulmonary Assist System (PAS) is currently under development as a wearable respiratory assist system. In this study, the hemocompatibility of the PAS's axial-flow mechanical pump (AFP) was compared to other contemporary mechanical pumps in an acute ovine model. The PAS was attached to a normal sheep in a venovenous configuration using one of three pumps: 1) AFP, 2) ReliantHeart HeartAssist 5 (control), or 3) Abbott Pedimag (control) (n = 5 each). Each sheep was supported on the PAS for 12 hours with two L/minute of blood flow and four L/minute of sweep gas. Hemolysis, coagulation, inflammation, and platelet activation and loss were compared among the groups. In this study, the plasma-free hemoglobin (pfHb) was less than 10 mg/dl in all groups. The pfHb was significantly lower in the AFP group compared to other groups. There was no significant clot formation in the pumps and oxygenators in all groups. Furthermore, no significant differences in coagulation (oxygenator resistance, fibrinopeptide A), inflammation (white blood cell counts, IL-8), and platelet activation and loss (p-selectin, platelet counts) were observed among the groups (all, p > 0.05). This study demonstrates equivalent hemocompatibility of the PAS's AFP to other contemporary mechanical pumps with a reduced level of hemolysis on startup.

Indications and Outcomes for Adult Extracorporeal Membrane Oxygenation at a Military Referral Facility

INTRODUCTION

Extracorporeal life support, including extracorporeal membrane oxygenation (ECMO), is a potentially life-saving adjunct to therapy in patients experiencing pulmonary and/or cardiac failure. The U.S. DoD has only one ECMO center, in San Antonio, Texas. In this study, we aimed to analyze outcomes at this center in order to determine whether they are on par with those reported elsewhere in the literature.

MATERIALS AND METHODS

In this observational study, we analyzed data from patients treated with ECMO at the only DoD ECMO center between September 2012 and April 2020. The primary outcome was survival to discharge, and secondary outcomes were discharge disposition and incidence of complications.

RESULTS

One hundred and forty-three patients were studied, with a 70.6% rate of survival to discharge. Of the patients who survived, 32.7% were discharged home; 32.7% were discharged to a rehabilitation facility; and 33.7% were transferred to another hospital, 29.4% of whom were transferred to lung transplant centers. One patient left against medical advice. Incidence of ECMO-related complications were as follows: 64 patients (44.7%) experienced hemorrhagic complications, 80 (55.9%) had renal complications, 61 (42.6%) experienced cardiac complications, 39 (27.3%) had pulmonary complications, and 5 patients (3.5%) experienced limb ischemia. We found that these outcomes were comparable to those reported in the literature.

CONCLUSIONS

Extracorporeal membrane oxygenation can be an efficacious adjunct in management of critically ill patients who require pulmonary and/or cardiac support. This single-center observational study demonstrated that the DoD's only ECMO center has outcomes comparable with the reported data in Extracorporeal Life Support Organization's registry.

In vitro study on device-induced damage to blood cellular components and degradation of von Willebrand factor in a CentriMag pump-assisted circulation

BACKGROUND

High mechanical shear stress (HMSS) generated by blood pumps during mechanical circulatory support induces blood damage (or function alteration) not only of blood cell components but also of plasma proteins.

METHODS

In the present study, fresh, healthy human blood was used to prime a blood circuit assisted by a CentriMag centrifugal pump at a flow rate of 4.5 L/min under three pump pressure heads (75, 150, and 350 mm Hg) for 4 h. Blood samples were collected for analyses of plasma-free hemoglobin (PFH), von Willebrand factor (VWF) degradation and platelet glycoprotein (GP) IIb/IIIa receptor shedding.

RESULTS

The extent of all investigated aspects of blood damage increased with increasing cross-pump pressure and duration. Loss of high-molecular-weight multimers (HMWM)-VWF in Loop 2 and Loop 3 significantly increased after 2 h. PFH, loss of HMWM-VWF, and platelet GPIIb/IIIa receptor shedding showed a good linear correlation with mean shear stress corresponding to the three pump pressure heads.

CONCLUSIONS

HMSS could damage red blood cells, cause pathological VWF degradation, and induce platelet activation and platelet receptor shedding. Different blood components can be damaged to different degrees by HMSS; VWF and VWF-enhanced platelet activation may be more susceptible to HMSS.

Carboxyhemoglobin predicts oxygenator performance and imminent oxygenator change in extracorporeal membrane oxygenation

BACKGROUND

The continuous exposure of blood to a non-biological surface during extracorporeal membrane oxygenation (ECMO) may lead to progressive thrombus formation in the oxygenator, hemolysis and consequently impaired gas exchange. In most centers oxygenator performance is monitored only on a once daily basis. Carboxyhemoglobin (COHb) is generated upon red cell lysis and is routinely measured with any co-oximetry performed to surveille gas exchange and acid-base homeostasis every couple of hours. This retrospective cohort study aims to evaluate COHb in the arterial blood gas as a novel marker of oxygenator dysfunction and its predictive value for imminent oxygenator change.

RESULTS

Out of the 484 screened patients on ECMO 89, cumulatively requiring 116 oxygenator changes within 1833 patient days, including 19,692 arterial COHb measurements were analyzed. Higher COHb levels were associated with lower post-oxygenator pO2 (estimate for log(COHb): - 2.176 [95% CI - 2.927, - 1.427], p < 0.0001) and with a shorter time to oxygenator change (estimate for log(COHb): - 67.895 [95% CI - 74.209, - 61.542] hours, p < 0.0001). COHb was predictive of oxygenator change within 6 h (estimate for log(COHb): 5.027 [95% CI 1.670, 15.126], p = 0.004).

CONCLUSION

COHb correlates with oxygenator performance and can be predictive of imminent oxygenator change. Therefore, longitudinal measurements of COHb in clinical routine might be a cheap and more granular candidate for ECMO surveillance that should be further analyzed in a controlled prospective trial design.

Multi-Method Investigation of Blood Damage Induced By Blood Pumps in Different Clinical Support Modes

To investigate the effects of blood pumps operated in different modes on nonphysiologic flow patterns, cell and protein function, and the risk of bleeding, thrombosis, and hemolysis, an extracorporeal blood pump (CentriMag) was operated in three clinical modalities including heart failure (HF), venous-venous (V-V) extracorporeal membrane oxygenation (ECMO), and venous-arterial (V-A) ECMO. Computational fluid dynamics (CFD) methods and coupled hemolysis models as well as recently developed bleeding and thrombosis models associated with changes in platelet and von Willebrand factor (vWF) function were used to predict hydraulic performance and hemocompatibility. The V-A ECMO mode had the highest flow losses and shear stress levels, the V-V ECMO mode was intermediate, and the HF mode was the lowest. Different nonphysiologic flow patterns altered cell/protein morphology and function. The V-A ECMO mode resulted in the highest levels of platelet activation, receptor shedding, vWF unfolding, and high molecular weight multimers vWF (HMWM-vWF) degradation, leading to the lowest platelet adhesion and the highest vWF binding capacity, intermediate in the V-V ECMO mode, and opposite in the HF mode. The V-A ECMO mode resulted in the highest risk of bleeding, thrombosis, and hemolysis, with the V-V ECMO mode intermediate and the HF mode lowest. These findings are supported by published experimental or clinical statistics. Further studies found that secondary blood flow passages resulted in the highest risk of blood damage. Nonphysiologic blood flow patterns were strongly associated with cell and protein function changing, blood damage, and complications.

Undiagnosed Perihepatic Abscess Revealed at Autopsy of a Patient With COVID-19 Undergoing Prolonged Extracorporeal Membrane Oxygenation (ECMO) Therapy

The use of extracorporeal membrane oxygenation (ECMO) increased during the COVID-19 pandemic. However, complications associated with the long-term use of ECMO are poorly understood. This case report describes the autopsy findings of a perihepatic abscess in a patient with long-term COVID-19, which could not be diagnosed before death. In cases where the source of infection remains elusive but uncontrolled infections occur, we recommend the combined use of ultrasonography and contrast-enhanced computed tomography (CT) in patients with COVID-19 undergoing prolonged ECMO support, with particular consideration given to the potential development of cholecystitis.

Hemodynamic management of cardiogenic shock in the intensive care unit

Hemodynamic derangements are defining features of cardiogenic shock. Randomized clinical trials have examined the efficacy of various therapeutic interventions, from percutaneous coronary intervention to inotropes and mechanical circulatory support (MCS). However, hemodynamic management in cardiogenic shock has not been well-studied. This State-of-the-Art review will provide a framework for hemodynamic management in cardiogenic shock, including a description of the 4 therapeutic phases from initial 'Rescue' to 'Optimization', 'Stabilization' and 'de-Escalation or Exit therapy' (R-O-S-E), phenotyping and phenotype-guided tailoring of pharmacological and MCS support, to achieve hemodynamic and therapeutic goals. Finally, the premises that form the basis for clinical management and the hypotheses for randomized controlled trials will be discussed, with a view to the future direction of cardiogenic shock.

A Case of Acute Mechanical Mitral Valve Thrombosis Management With Venoarterial Extracorporeal Membrane Oxygenation

Mechanical prosthetic valve thrombosis (PVT) and obstruction are rare and dangerous events often related to inappropriate anticoagulant therapy. High mortality rates occur because of delayed diagnosis, hemodynamic instability, multiple organ failure (MOF), and high perioperative risk. Surgical repair is a first-line treatment for obstructive PVT with hemodynamic instability but is often not readily available or safely performed. Venoarterial extracorporeal membrane oxygenation (VA ECMO) support has been increasingly used in patients with PVT and cardiorespiratory collapse, allowing MOF reversal and safer deferred surgery. The authors present a case of a young female with refractory cardiogenic shock secondary to mitral PVT successfully managed with VA ECMO. Furthermore, the promising role of perioperative VA ECMO support for PVT-related cardiogenic shock is also discussed.

Improving ECMO therapy: Monitoring oxygenator functionality and identifying key indicators, factors, and considerations for changeout

INTRODUCTION

The optimal timing for extracorporeal membrane oxygenation (ECMO) circuit change-out is crucial for the successful management of patients with severe cardiopulmonary failure. This comprehensive review examines the various factors that influence the timing of oxygenator replacement in the ECMO circuit. By considering these factors, clinicians can make informed decisions to ensure timely and effective change-out, enhancing patient outcomes and optimizing the delivery of ECMO therapy.

METHODOLOGY

A thorough search of relevant studies on ECMO circuits and oxygenator change-out was conducted using multiple scholarly databases and relevant keywords. Studies published between 2017 and 2023 were included, resulting in 40 studies that met the inclusion criteria.

DISCUSSION

Thrombosis within the membrane oxygenator and its impact on dysfunction were identified as significant contributors, highlighting the importance of monitoring coagulation parameters and gas exchange. Several factors, including fibrinogen levels, pre and post-membrane blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows and pressures, and anticoagulation strategy, were found to be important considerations when determining the need for an oxygenator or circuit change-out. The involvement of a multidisciplinary team and thorough preparation were also highlighted as crucial aspects of this process.

CONCLUSION

In conclusion, managing circuit change-outs in ECMO therapy requires considering factors such as fibrinogen levels, blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows, pressures, and anticoagulation strategy. Monitoring these parameters allows for early detection of issues, timely interventions, and optimized ECMO therapy. Standardized protocols, personalized anticoagulation approaches, and non-invasive monitoring techniques can improve the safety and effectiveness of circuit change-outs. Further research and collaboration are needed to advance ECMO management and enhance patient outcomes.

Concurrent use of continuous kidney replacement therapy during extracorporeal membrane oxygenation: what pediatric nephrologists need to know-PCRRT-ICONIC practice points

Extracorporeal membrane oxygenation (ECMO) provides temporary cardiorespiratory support for neonatal, pediatric, and adult patients when traditional management has failed. This lifesaving therapy has intrinsic risks, including the development of a robust inflammatory response, acute kidney injury (AKI), fluid overload (FO), and blood loss via consumption and coagulopathy. Continuous kidney replacement therapy (CKRT) has been proposed to reduce these side effects by mitigating the host inflammatory response and controlling FO, improving outcomes in patients requiring ECMO. The Pediatric Continuous Renal Replacement Therapy (PCRRT) Workgroup and the International Collaboration of Nephrologists and Intensivists for Critical Care Children (ICONIC) met to highlight current practice standards for ECMO use within the pediatric population. This review discusses ECMO modalities, the pathophysiology of inflammation during an ECMO run, its adverse effects, various anticoagulation strategies, and the technical aspects and outcomes of implementing CKRT during ECMO in neonatal and pediatric populations. Consensus practice points and guidelines are summarized. ECMO should be utilized in patients with severe acute respiratory failure despite the use of conventional treatment modalities. The Extracorporeal Life Support Organization (ELSO) offers guidelines for ECMO initiation and management while maintaining a clinical registry of over 195,000 patients to assess outcomes and complications. Monitoring and preventing fluid overload during ECMO and CKRT are imperative to reduce mortality risk. Clinical evidence, resources, and experience of the nephrologist and healthcare team should guide the selection of ECMO circuit.

A Comprehensive Review of Extra Corporeal Membrane Oxygenation: The Lifeline in Critical Moments

Extracorporeal membrane oxygenation (ECMO) has evolved into a pivotal intervention in critical care, offering a lifeline for patients facing severe respiratory or cardiac failure. This review provides a comprehensive exploration of ECMO, spanning its definition and historical background to its contemporary advancements and ongoing impact in critical care. The versatility of ECMO in addressing diverse critical conditions, careful patient selection criteria, and the nuanced management of complications are discussed. Advances in technology, including miniaturization, novel circuit designs, and the integration of remote monitoring, showcase the evolving landscape of ECMO. The review underscores the ongoing impact of ECMO in improving survival rates, enhancing mobility, and enabling remote expertise. As a symbol of hope and innovation, ECMO's lifesaving potential is evident in its ability to navigate the complexities of critical care and redefine the boundaries of life support interventions.

Characterizing the Racial Discrepancy in Hypoxemia Detection in VV-ECMO: An ELSO Registry Analysis

Importance : Skin pigmentation influences peripheral oxygen saturation (SpO 2 ) measured by pulse oximetry compared to the arterial saturation of oxygen (SaO 2 ) measured via arterial blood gas analysis. However, data on SpO 2 -SaO 2 discrepancy are limited in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients. Objective : To determine whether there is racial/ethnical discrepancy between SpO 2 and SaO 2 in patients receiving VV-ECMO. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO 2 -SaO 2 discrepancy due to significant hemolysis. Design : Retrospective cohort study of the Extracorporeal Life Support Organization Registry from 1/2018-5/2023. Setting : International, multicenter registry study including over 500 ECMO centers. Participants : Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO 2 and SaO 2 measurements. Exposure : Race/ethnicity and ECMO cannulation. Main outcomes and measures : Occult hypoxemia (SaO 2  ≤ 88% with SpO 2  ≥ 92%) was our primary outcome. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO 2 -SaO 2 calculations. Covariates included age, sex, temporary mechanical circulatory support, pre-vasopressors, and pre-inotropes for pre-ECMO analysis, plus single-lumen versus double-lumen cannulation, hemolysis, hyperbilirubinemia, ECMO pump flow rate, and on-ECMO 24h lactate for on-ECMO analysis. Results : Of 13,171 VV-ECMO patients (median age = 48.6 years, 66% male), there were 7,772 (59%) White, 2,114 (16%) Hispanic, 1,777 (14%) Black, and 1,508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% ( N =  233). Occult hypoxemia was more common in Black and Hispanic versus White patients (3.1% versus 1.7%, P  < 0.001 and 2.5% versus 1.7%, P =  0.025, respectively). In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P =  0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95%CI = 1.16-2.75, P =  0.008) and Hispanic patients (aOR = 1.71, 95%CI = 1.15-2.55, P =  0.008) had higher risk versus White patients. Furthermore, higher pump flow rate (aOR = 1.29, 95%CI = 1.08-1.55, P =  0.005) and higher on-ECMO 24h lactate (aOR = 1.06, 95%CI = 1.03-1.10, P  < 0.001) significantly increased the risk of on-ECMO occult hypoxemia. Conclusions and Relevance : Hispanic and Black VV-ECMO patients experienced occult hypoxemia more than White patients. SaO 2 should be carefully monitored during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.

Post-Mortem Extracorporeal Membrane Oxygenation Perfusion Rat Model: A Feasibility Study

The development of biomedical soft- or hardware frequently includes testing in animals. However, large efforts have been made to reduce the number of animal experiments, according to the 3Rs principle. Simultaneously, a significant number of surplus animals are euthanized without scientific necessity. The primary aim of this study was to establish a post-mortem rat perfusion model using extracorporeal membrane oxygenation (ECMO) in surplus rat cadavers and generate first post vivo results concerning the oxygenation performance of a recently developed ECMO membrane oxygenator. Four rats were euthanized and connected post-mortem to a venous-arterial ECMO circulation for up to eight hours. Angiographic perfusion proofs, blood gas analyses and blood oxygenation calculations were performed. The mean preparation time for the ECMO system was 791 ± 29 s and sufficient organ perfusion could be maintained for 463 ± 26 min, proofed via angiographic imaging and a mean femoral arterial pressure of 43 ± 17 mmHg. A stable partial oxygen pressure, a 73% rise in arterial oxygen concentration and an exponentially increasing oxygen extraction ratio up to 4.75 times were shown. Considering the 3Rs, the established post-mortal ECMO perfusion rat model using surplus animals represents a promising alternative to models using live animals. Given the preserved organ perfusion, its use could be conceivable for various biomedical device testing.

Venovenous Versus Venoarterial Extracorporeal Membrane Oxygenation: Pediatric Acute Respiratory Distress Syndrome

OBJECTIVE

This study aimed to compare the efficacy, complication, and mortality of patients who were supported by venovenous (VV) extracorporeal membrane oxygenation (ECMO) and venoarterial (VA) ECMO for pediatric acute respiratory distress syndrome (PARDS).

MATERIALS AND METHODS

This study is a single-center, retrospective cohort study between 2014 and 2022. We evaluated to indication of ECMO support, ECMO type, patients' demographic features, complications, and children's outcomes supported by ECMO for PARDS.

RESULTS

Twenty-two patients with PARDS, 12 (54%) with VV, and 10 (46%) with VA ECMO were selected. The median number of days to be intubated before ECMO cannulation was 5 (0-16) days. The distribution of intubated days before the patients underwent ECMO was as follows: 0-1 days, 7 (31.8%) patients; 2-3 days, 2 (9.1%) patients; 4-7 days, 7 (31.8%) patients; 8-14 days, 5 (22.8%) patients; >14 days, 1 (4.5%) patient. The median ECMO cannulation day after admission to the pediatric intensive care unit was 3 (range, 1-9) days in the VV ECMO patient group, whereas it was 8 (range, 0-19) days in the VA ECMO group (P = .02). Considering hospital survival, 4 (45%) patients who underwent double-lumen VV ECMO, 1 (33%) patient who underwent VV ECMO, and 3 (30%) patients who supported by VAECMO survived. There was no difference between the groups in terms of hospital discharge rates.

CONCLUSION

The highest survival rate was found in the VV ECMO patient group established with double-lumen cannulas, similar to the literature. There was no difference in mortality between the groups whose intubation time before ECMO was 14 days or less.

Smaller Return Cannula in Venoarterial Extracorporeal Membrane Oxygenation Does Not Increase Hemolysis: A Single-Center, Cohort Study

The aim of this study was to explore the association between arterial return cannula diameter and hemolysis during peripheral VA ECMO. We identified 158 adult patients who received peripheral VA ECMO at our institution from the national ECMO database (EXCEL) between January 2019 and July 2021. We classified patients into a small cannula group (15 Fr diameter, n = 45) and a large cannula group (≥17 Fr diameter, n = 113), comparing incidences of clinical hemolysis and plasma free hemoglobin ( pf Hb). Moderate hemolysis is defined as having pf Hb 0.05-0.10 g/L and severe hemolysis as having pf Hb >0.10 g/L sustained for at least two consecutive readings or leading to a circuit change. There were no significant differences in rates of moderate hemolysis between small and large cannula groups (1 vs . 6; p = 0.39) and severe hemolysis (0 vs . 3; p = 0.27), nor was the pf Hb level significantly different at 4 hours (0.086 ± 0.096 vs . 0.112 ± 0.145 g/L; p = 0.58) and at 24 hours (0.042 ± 0.033 vs . 0.051 ± 0.069 g/L; p = 0.99). There were no increased rates of hemolysis when comparing small versus large arterial return cannula diameter in peripheral VA ECMO.

Confounders for prognostic accuracy of neuron-specific enolase after cardiac arrest: A retrospective cohort study

AIM

To evaluate neuron-specific enolase (NSE) thresholds for prediction of neurological outcome after cardiac arrest and to analyze the influence of hemolysis and confounders.

METHODS

Retrospective analysis from a cardiac arrest registry. Determination of NSE serum concentration and hemolysis-index (h-index) 48-96 hours after cardiac arrest. Evaluation of neurological outcome using the Cerebral Performance Category score (CPC) at hospital discharge. Separate analyses considering CPC 1-3 and CPC 1-2 as good neurological outcome. Analysis of specificity and sensitivity for poor and good neurological outcome prediction with and without exclusion of hemolytic samples (h-index larger than 50).

RESULTS

Among 356 survivors three days after cardiac arrest, hemolysis was detected in 28 samples (7.9%). At a threshold of 60 µg/L, NSE predicted poor neurological outcome (CPC 4-5) in all samples with a specificity of 92% (86-95%) and sensitivity of 73% (66-79%). In non-hemolytic samples, specificity was 94% (89-97%) and sensitivity 70% (62-76%). At a threshold of 100 µg/L, specificity was 98% (95-100%, all samples) and 99% (95-100%, non-hemolytic samples), and sensitivity 58% (51-65%) and 55% (47-63%), respectively. Possible confounders for elevated NSE in patients with good neurological outcome were ECMO, malignancies, blood transfusions and acute brain diseases. Nine patients with NSE below 17 µg/L had CPC 5, all had plausible death causes other than hypoxic-ischemic encephalopathy.

CONCLUSIONS

NSE concentrations higher than 100 µg/L predicted poor neurological outcome with high specificity. An NSE less than 17 µg/L indicated absence of severe hypoxic-ischemic encephalopathy. Hemolysis and other confounders need to be considered.

INSTITUTIONAL PROTOCOL NUMBER

The local ethics committee (board name: Ethikkommission der Charité) approved this study by the number: EA2/066/23, approval date: 28th June 2023, study title "'ROSC' - Resuscitation Outcome Study."

U-Shaped Association Between Carboxyhemoglobin and Mortality in Patients With Acute Respiratory Distress Syndrome on Venovenous Extracorporeal Membrane Oxygenation

Background

Carbon monoxide (CO) is an endogenous signaling molecule that activates cytoprotective programs implicated in the resolution of acute respiratory distress syndrome (ARDS) and survival of critical illness. Because CO levels can be measured in blood as carboxyhemoglobin, we hypothesized that carboxyhemoglobin percent (COHb%) may associate with mortality.

OBJECTIVES

To examine the relationship between COHb% and outcomes in patients with ARDS requiring venovenous extracorporeal membrane oxygenation (ECMO), a condition where elevated COHb% is commonly observed.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center ICU.

PATIENTS

Patients were included that had ARDS on venovenous ECMO.

MEASUREMENTS AND MAIN RESULTS

We examined the association between COHb% and mortality using a Cox proportional hazards model. Secondary outcomes including ECMO duration, ventilator weaning, and hospital and ICU length of stay were examined using both subdistribution and causal-specific hazard models for competing risks. We identified 109 consecutive patients for analysis. Mortality significantly decreased per 1 U increase in COHb% below 3.25% (hazard ratio [HR], 0.35; 95% CI, 0.15-0.80; p = 0.013) and increased per 1 U increase above 3.25% (HR, 4.7; 95% CI, 1.5-14.7; p = 0.007) reflecting a nonlinear association (p = 0.006). Each unit increase in COHb% was associated with reduced likelihood of liberation from ECMO and mechanical ventilation, and increased time to hospital and ICU discharge (all p < 0.05). COHb% was significantly associated with hemolysis but not with initiation of hemodialysis or blood transfusions.

CONCLUSIONS

In patients with ARDS on venovenous ECMO, COHb% is a novel biomarker for mortality exhibiting a U-shaped pattern. Our findings suggest that too little CO (perhaps due to impaired host signaling) or excess CO (perhaps due to hemolysis) is associated with higher mortality. Patients with low COHb% may exhibit the most benefit from future therapies targeting anti-oxidant and anti-inflammatory pathways such as low-dose inhaled CO gas.

A novel role of acellular hemoglobin in hemolytic thrombosis

BACKGROUND

Hemolytic thrombosis has been associated with acellular hemoglobin released from damaged red blood cells during hemolysis. However, the precise molecular mechanism underlying acellular hemoglobin-induced thrombosis remains arguable. In this study, we examined the interaction between hemoglobin and the A1 domain of von Willebrand factor (VWF), which is a critical mediator of platelet activation.

METHODS

Previous studies have suggested that the interaction between hemoglobin and the A1 domain of VWF enhances VWF's hemostatic activity. We employed a multidisciplinary investigation to re-examine this interaction, and identified significant differences in binding affinity between the active and inactive forms of A1.

RESULTS

We found that hemoglobin binds more strongly to the active A1 than the inactive form. Using hydrogen‑deuterium exchange mass spectrometry, we identified the specific residues involved in this interaction, which are located on the α1-β2 and β3-α2 loops that are typically covered by the "autoinhibitory module" in the inactive A1. This observation provides a structural explanation for the differential binding affinity between the active and inactive forms of A1. We demonstrated that the binding of hemoglobin to A1 blocks the interaction between GPIbα and VWF, and inhibits VWF-mediated thrombosis in vivo. Furthermore, we found that administration of hemoglobin led to similar levels of thrombocytopenia and microthrombosis in both wildtype and VWF-deficient mice, indicating that the mechanism underlying acellular hemoglobin-induced thrombosis is VWF-independent.

CONCLUSIONS

These findings challenge the previous theory that hemoglobin-induced thrombosis occurs solely through binding with VWF, and provide evidence supporting a novel role for hemoglobin in hemolytic thrombosis.

The Hematological Effects of Extracorporeal Membrane Oxygenator Exchange

Membrane oxygenator failure during venovenous (V-V) extracorporeal membrane oxygenation (ECMO) can lead to life-threatening hypoxia, high replacement costs, and may be associated with a hyperfibrinolytic state and bleeding. The current understanding of the underlying mechanisms that drive this is limited. The primary aim of this study therefore is to investigate the hematological changes that occur before and after membrane oxygenator and circuit exchanges (ECMO circuit exchange) in patients with severe respiratory failure managed on V-V ECMO. We analyzed 100 consecutive V-V ECMO patients using linear mixed-effects modeling to evaluate hematological markers in the 72 hours before and 72 hours after ECMO circuit exchange. A total of 44 ECMO circuit exchanges occurred in 31 of 100 patients. The greatest change from baseline to peak were seen in plasma-free hemoglobin (42-fold increase p < 0.01) and the D-dimer:fibrinogen ratio (1.6-fold increase p = 0.03). Bilirubin, carboxyhemoglobin, D-dimer, fibrinogen, and platelets also showed statistically significant changes ( p < 0.01), whereas lactate dehydrogenase did not ( p = 0.93). Progressively deranged hematological markers normalize more than 72 hours after ECMO circuit exchange, with an associated reduction in membrane oxygenator resistance. This supports the biologic plausibility that ECMO circuit exchange may prevent further complications such as hyperfibrinolysis, membrane failure, and clinical bleeding.

Circuit change during extracorporeal membrane oxygenation: single-center retrospective study of 48 changes

BACKGROUND

Bleeding and thrombosis induce major morbidity and mortality in patients under extracorporeal membrane oxygenator (ECMO). Circuit changes can be performed for oxygenation membrane thrombosis but are not recommended for bleeding under ECMO. The objective of this study was to evaluate the course of clinical, laboratory, and transfusion parameters before and after ECMO circuit changes warranted by bleeding or thrombosis.

METHODS

In this single-center, retrospective, cohort study, clinical parameters (bleeding syndrome, hemostatic procedures, oxygenation parameters, transfusion) and laboratory parameters (platelet count, hemoglobin, fibrinogen, PaO₂) were collected over the seven days surrounding the circuit change.

RESULTS

In the 274 patients on ECMO from January 2017 to August 2020, 48 circuit changes were performed in 44 patients, including 32 for bleeding and 16 for thrombosis. Mortality was similar in the patients with vs. without changes (21/44, 48% vs. 100/230, 43%) and in those with bleeding vs. thrombosis (12/28, 43% vs. 9/16, 56%, P = 0.39). In patients with bleeding, numbers of bleeding events, hemostatic procedures, and red blood cell transfusions were significantly higher before vs. after the change (P < 0.001); the platelet counts and fibrinogen levels decreased progressively before and increased significantly after the change. In patients with thrombosis, numbers of bleeding events and red blood cell transfusions did not change after membrane change. No significant differences were demonstrated between oxygenation parameters (ventilator FiO₂, ECMO FiO₂, and PaO₂) and ECMO flow before vs. after the change.

CONCLUSIONS

In patients with severe and persistent bleeding, changing the ECMO circuit decreased clinical bleeding and red blood cell transfusion needs and increased platelets and fibrinogen levels. Oxygenation parameters did not change significantly in the group with thrombosis.

A Clinical-Scale Microfluidic Respiratory Assist Device with 3D Branching Vascular Networks

Recent global events such as COVID-19 pandemic amid rising rates of chronic lung diseases highlight the need for safer, simpler, and more available treatments for respiratory failure, with increasing interest in extracorporeal membrane oxygenation (ECMO). A key factor limiting use of this technology is the complexity of the blood circuit, resulting in clotting and bleeding and necessitating treatment in specialized care centers. Microfluidic oxygenators represent a promising potential solution, but have not reached the scale or performance required for comparison with conventional hollow fiber membrane oxygenators (HFMOs). Here the development and demonstration of the first microfluidic respiratory assist device at a clinical scale is reported, demonstrating efficient oxygen transfer at blood flow rates of 750 mL min⁻1 , the highest ever reported for a microfluidic device. The central innovation of this technology is a fully 3D branching network of blood channels mimicking key features of the physiological microcirculation by avoiding anomalous blood flows that lead to thrombus formation and blood damage in conventional oxygenators. Low, stable blood pressure drop, low hemolysis, and consistent oxygen transfer, in 24-hour pilot large animal experiments are demonstrated - a key step toward translation of this technology to the clinic for treatment of a range of lung diseases.

Turbulence in surgical suction heads as detected by MRI

BACKGROUND

Blood loss is common during surgical procedures, especially in open cardiac surgery. Allogenic blood transfusion is associated with increased morbidity and mortality. Blood conservation programs in cardiac surgery recommend re-transfusion of shed blood directly or after processing, as this decreases transfusion rates of allogenic blood. But aspiration of blood from the wound area is often associated with increased hemolysis, due to flow induced forces, mainly through development of turbulence.

METHODS

We evaluated magnetic resonance imaging (MRI) as a qualitative tool for detection of turbulence. MRI is sensitive to flow; this study uses velocity-compensated T1-weighted 3D MRI for turbulence detection in four geometrically different cardiotomy suction heads under comparable flow conditions (0-1250 mL/min).

RESULTS

Our standard control suction head Model A showed pronounced signs of turbulence at all flow rates measured, while turbulence was only detectable in our modified Models 1-3 at higher flow rates (Models 1 and 3) or not at all (Model 2).

CONCLUSIONS

The comparison of flow performance of surgical suction heads with different geometries via acceleration-sensitized 3D MRI revealed significant differences in turbulence development between our standard control Model A and the modified alternatives (Models 1-3). As flow conditions during measurement have been comparable, the specific geometry of the respective suction heads must have been the main factor responsible. The underlying mechanisms and causative factors can only be speculated about, but as other investigations have shown, hemolytic activity is positively associated with degree of turbulence. The turbulence data measured in this study correlate with data from other investigations about hemolysis induced by surgical suction heads. The experimental MRI technique used showed added value for further elucidating the underlying physical phenomena causing blood damage due to non-physiological flow.

Risk factors for elective and emergency oxygenator exchanges during veno-venous extracorporeal membrane oxygenation

BACKGROUND

Despite systemic anticoagulation and antithrombotic surface coating, oxygenator dysfunction remains one of most common technical complications of Extracorporeal membrane oxygenation (ECMO). Several parameters have been associated with an oxygenator exchange, but no guidelines for when to perform an exchange are published. An exchange, especially an emergency exchange, has a risk of complications. Therefore, a delicate balance between oxygenator dysfunction and the exchange of the oxygenator exists. This study aimed to identify risk factors and predictors for elective and emergency oxygenator exchanges.

METHODS

This observational cohort study included all adult patients supported with veno-venous extracorporeal membrane oxygenation (V-V ECMO). We compared patients' characteristics and laboratory values of patients with and without an oxygenator exchange and between an elective and emergency exchange, defined as an exchange outside office hours. Risk factors for an oxygenator exchange were identified with cox regression analyses, and risk factors for an emergency exchange were identified with logistic regression analyses.

RESULTS

We included forty-five patients in the analyses. There were twenty-nine oxygenator exchanges in nineteen patients (42%). More than a third of the exchanges were emergency exchanges. Higher partial pressure of carbon dioxide (PaCO2), transmembrane pressure difference (ΔP), and hemoglobin (Hb) were associated with an oxygenator exchange. Lower lactate dehydrogenase (LDH) was the only risk factor for an emergency exchange.

CONCLUSION

Oxygenator exchange is frequent during V-V ECMO support. PaCO2, ΔP and Hb were associated with an oxygenator exchange and lower LDH with the risk of an emergency exchange.

Research status and development trend of extracorporeal membrane oxygenation based on bibliometrics

Background

Using bibliometric method to analyze the research status and development trend of extracorporeal membrane oxygenation (ECMO), we aim to provide clinicians, scientists, and stakeholders with the most up-to-date and comprehensive overview of ECMO research.

Materials and methods

Using Excel and VOSviewer, the literature on ECMO was systematically analyzed regarding publication trends, journal source, foundation, countries, institutions, core authors, research hotspots, and market distribution.

Results

There were five important time nodes in the research process of ECMO, including the success of the first ECMO operation, the establishment of ELSO, and the outbreak of influenza A/H1N1 and COVID-19. The R&amp;D centers of ECMO were the United States, Germany, Japan, and Italy, and the attention to ECMO was gradually increasing in China. The products most used in the literature were from Maquet, Medtronic, and LivaNova. Medicine enterprises attached great importance to the funding of ECMO research. In recent years, the literature has mainly focused on the following aspects: the treatment of ARDS, the prevention of coagulation system-related complications, the application in neonatal and pediatric patients, mechanical circulatory support for cardiogenic shock, and ECPR and ECMO during the COVID-19 pandemic.

Conclusion

The frequent epidemic occurrence of viral pneumonia and the technical advancement of ECMO in recent years have caused an increase in clinical applications. The hot spots of ECMO research are shown in the treatment of ARDS, mechanical circulatory support for cardiogenic shock, and the application during the COVID-19 pandemic.

Extended Cellular Deposits on Gas Exchange Capillaries are Not an Indicator of Clot Formation: Analysis of Different Membrane Oxygenators

Antithrombogenic coatings of artificial surfaces within extracorporeal membrane oxygenation (ECMO) circuits improved its bio- and hemocompatibility. However, there is still a risk of thrombus formation in particular within the membrane oxygenator (MO). Since inflammatory cells are essential components within clots, the aim was to identify the extent of cellular accumulations on gas exchange capillaries from different ECMO systems. Thirty-four MOs (PLS, n = 27, Getinge; Hilite 7000 LT, n = 7, Fresenius Medical Care, Germany) were collected from adult patients. The extent of cellular deposits on gas exchange capillaries was classified using nuclear 4',6-diamidino-2-phenylindole staining and fluorescence microscopy. All Hilite oxygenators exhibited small cellular deposits. In contrast, the cellular distribution was heterogeneous on capillaries from PLS oxygenators: small deposits (34%), clusters (44%) and membrane-spanning cell structures (pseudomembranes) (22%). Overall, the median fluorescence intensity was significantly higher in the PLS group. Nevertheless, within 3 days before MO removal, there was no alteration in critical parameters (d-dimer and fibrinogen levels, platelet counts, and pressure drop across the MO). In conclusion, despite the histological differences on the gas capillaries from different types of oxygenators, there was no further evidence of increased inflammation and coagulation parameters that indicate clot formation within oxygenators.

Use of fondaparinux in patients with heparin-induced thrombocytopenia on veno-venous extracorporeal membrane oxygenation: A three-patient case series report

Heparin-induced thrombocytopenia is a life-threatening immune-mediated complication of unfractionated heparin therapy. Fondaparinux is a therapeutic alternative, but it has limited evidence for its use in patients on extracorporeal membrane oxygenation (ECMO). We present a series of three adult patients with COVID-19 on ECMO who were diagnosed with heparin-induced thrombocytopenia after 7-12 days of unfractionated heparin treatment and were switched to fondaparinux. Fondaparinux was initiated with an intravenous loading dose of 5 mg, followed by a dose of 2.5 mg subcutaneously every 8-12 h. Dosage was adjusted according to daily measured anti-Xa concentration with a target range of 0.4-0.7 mg/L. The total duration of treatment with fondaparinux and ECMO ranged from 13 to 26 days. One major bleeding episode unrelated to fondaparinux therapy was observed, and the transfusions requirement was also low in all patients. The ECMO circuit was changed once in each patient. This series provides a deep insight into the use of fondaparinux over an extended period of time in patients on ECMO. Based on the presented data, fondaparinux can be considered a reasonable and affordable anticoagulant in patients without a high risk of bleeding.

Application of a novel artificial perfusate based on oxygen-carrying nanoparticles in normothermic machine perfusion for porcine liver preservation after cardiac death

OBJECTIVE

To investigate the efficacy of a novel artificial perfusate based on oxygen-carrying perfluoronaphthalene-albumin nanoparticles in normothermic machine perfusion (NMP) for preservation of porcine liver donation after cardiac death.

METHODS

Artificial perfusate with perfluoronaphthalene-albumin nanoparticles was prepared at 5% albumin (w/v) and its oxygen carrying capacity was calculated. The livers of 16 Landrace pigs were isolated after 1 h of warm ischemia, and then they were divided into 4 groups and preserved continuously for 24 h with different preservation methods: cold preservation with UW solution (SCS group), NMP preservation by whole blood (blood NMP group), NMP preservation by artificial perfusate without nanoparticles (non-nanoparticles NMP group) and NMP preservation by artificial perfusate containing nanoparticles (nanoparticles NMP group). Hemodynamics, tissue metabolism, biochemical indices of perfusate and bile were monitored every 4 h after the beginning of NMP. Liver tissue samples were collected for histological examination (HE and TUNEL staining) before preservation, 12 h and 24 h after preservation.

RESULTS

The oxygen carrying capacity of nanoparticles in 100 mL artificial perfusate was 6.94 μL/mmHg (1 mmHg=0.133 kPa). The hepatic artery and portal vein resistance of nanoparticles NMP group and blood NMP group remained stable during perfusion, and the vascular resistance of nanoparticles NMP group was lower than that of blood NMP group. The concentration of lactic acid in the perfusate decreased to the normal range within 8 h in both nanoparticles NMP group and blood NMP group. There were no significant differences in accumulated bile production, alanine aminotransferase and aspartate aminotransferase in perfusate between nanoparticles NMP group and blood NMP group (all P>0.05). After 24 h perfusion, the histological Suzuki score in blood NMP group and nanoparticles NMP group was lower than that in SCS group and non-nanoparticles NMP group (all P<0.05), and the quantities of TUNEL staining positive cells in blood NMP group and non-nanoparticles NMP group was higher than those in nanoparticles NMP group and SCS group 12 h and 24 h after preservation (all P<0.05).

CONCLUSION

Artificial perfusate based on oxygen-carrying nanoparticles can meet the oxygen supply requirements of porcine livers donation after cardiac death during NMP preservation, and it may has superiorities in improving tissue microcirculation and alleviating ischemia-reperfusion injury.

Veno-venous Extracorporeal Membrane Oxygenation for pregnant women with Acute Respiratory Distress Syndrome: a narrative review

Acute respiratory distress syndrome remains an uncommon condition during pregnancy. In patients with severe acute respiratory distress syndrome, when oxygenation or ventilation cannot be supported sufficiently using best practice conventional mechanical ventilation and additional therapies, veno-venous extracorporeal membrane oxygenation may be considered. In the past two decades, there has been increasing adoption of this technique to support adult patients with refractory acute respiratory distress syndrome. However, its use for the management of pregnant women is rare and remains a challenge. This narrative review addresses acute respiratory distress syndrome and its management during pregnancy, and then focuses on indications, contraindications, challenges, potential complications, and outcomes of the use of veno-venous extracorporeal membrane oxygenation for acute respiratory distress syndrome in the pregnant patient.

Carboxyhemoglobin (CO-Hb) Correlates with Hemolysis and Hospital Mortality in Extracorporeal Membrane Oxygenation: A Retrospective Registry

Background: Patients supported with extracorporeal membrane oxygenation (ECMO) may develop elevated carboxyhemoglobin (CO-Hb), a finding described in the context of hemolysis. Clinical relevance of elevated CO-Hb in ECMO is unclear. We therefore investigated the prognostic relevance of CO-Hb during ECMO support. Methods: Data derives from a retrospective single-center registry study. All ECMO patients in a medical ICU from October 2010 through December 2019 were considered. Peak arterial CO-Hb value during ECMO support and median CO-Hb values determined by point-of-care testing for distinct time intervals were determined. Groups were divided by CO-Hb (<2% or ≥2%). The primary endpoint was hospital survival. Results: A total of 729 patients with 59,694 CO-Hb values met the inclusion criteria. Median age (IQR) was 59 (48−68) years, 221/729 (30.3%) were female, and 278/729 (38.1%) survived until hospital discharge. Initial ECMO configuration was veno-arterial in 431/729 (59.1%) patients and veno-venous in 298/729 (40.9%) patients. Markers for hemolysis (lactate dehydrogenase, bilirubin, hemolysis index, and haptoglobin) all correlated significantly with higher CO-Hb (p < 0.001, respectively). Hospital survival was significantly higher in patients with CO-Hb < 2% compared to CO-Hb ≥ 2%, evaluating time periods 24−48 h (48.6% vs. 35.2%, p = 0.003), 48−72 h (51.5% vs. 36.8%, p = 0.003), or >72 h (56.9% vs. 31.1%, p < 0.001) after ECMO cannulation. Peak CO-Hb was independently associated with lower hospital survival after adjustment for confounders. Conclusions: In ECMO, CO-Hb correlates with hemolysis and hospital survival. If high CO-Hb measured should trigger a therapeutic intervention in order to reduce hemolysis has to be investigated in prospective trials.

Eliminate Unnecessary Laboratory Work to Mitigate Iatrogenic Anemia and Reduce Cost for Patients on Extracorporeal Membrane Oxygenation

Laboratory testing is a helpful tool for clinicians, but can be costly and harmful to patients. A quality improvement project was initiated to reduce laboratory testing for patients receiving extracorporeal membrane oxygenation (ECMO) in a pediatric intensive care unit (PICU) at a tertiary care center. Preliminary data was gathered to demonstrate preimplementation practice, cost, and patient need for packed red blood cell (pRBC) transfusions. A new protocol was created by an interprofessional team based on best practice and benchmarking with high-performing organizations. The project was evaluated using two comparison groups, pre- and postimplementation for anyone receiving ECMO therapy in the PICU. The average laboratory tests per ECMO day decreased by 52% (128.4 vs. 61.1), cost per case decreased by 14.7%, pRBC transfusions decreased from 100% to 85%, length of stay (LOS) decreased by 8 days, and mortality rates decreased by 9.5%. The revised pediatric ECMO laboratory testing guidelines were successfully implemented and reduced laboratory cost without adverse effects on mortality rates or LOS.

Serum proteome alterations during conventional and extracorporeal resuscitation in pigs

Background

Only a small number of patients survive an out-of-hospital cardiac arrest (CA) and can be discharged from hospital alive with a large percentage of these patients retaining neurological impairments. In recent years, extracorporeal cardiopulmonary resuscitation (ECPR) has emerged as a beneficial strategy to optimize cardiac arrest treatment. However, ECPR is still associated with various complications. To reduce these problems, a profound understanding of the underlying mechanisms is required. This study aims to investigate the effects of CA, conventional cardiopulmonary resuscitation (CPR) and ECPR using a whole-body reperfusion protocol (controlled and automated reperfusion of the whole body—CARL) on the serum proteome profiles in a pig model of refractory CA.

Methods

N = 7 pigs underwent 5 min of untreated CA followed by 30 min CPR and 120 min perfusion with CARL. Blood samples for proteomic analysis were drawn at baseline, after CPR and at the end of the CARL period. Following albumin-depletion, proteomic analysis was performed using liquid chromatography–tandem mass spectrometry.

Results

N = 21 serum samples were measured resulting in the identification and quantification of 308–360 proteins per sample and 388 unique proteins in total. The three serum proteome profiles at the investigated time points clustered individually and segregated almost completely when considering a 90% confidence interval. Differential expression analysis showed significant abundance changes in 27 proteins between baseline and after CPR and in 9 proteins after CARL compared to CPR. Significant findings were further validated through a co-abundance cluster analysis corroborating the observed abundance changes.

Conclusions

The presented data highlight the impact of systemic ischemia and reperfusion on the entire serum proteome during resuscitation with a special focus on changes regarding haemolysis, coagulation, inflammation, and cell-death processes. Generally, the observed changes contribute to post-ischemic complications. Better understanding of the underlying mechanisms during CA and resuscitation may help to limit these complications and improve therapeutic options.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03441-4.

Overlooked but Serious Gallbladder Disease during Extracorporeal Membrane Oxygenation: A Retrospective Analysis

Background: To date, there have been no reports assessing the incidence, risk factors, and clinical outcomes of GB disease in patients receiving ECMO for cardiorespiratory failure. Methods: The medical records of adults (aged > 18 years) who underwent ECMO between May 2010 and October 2019 were retrospectively reviewed. We investigated the prevalence and related factors of GB disease during ECMO therapy, compared clinical outcomes between patients with and without GB disease, and performed propensity-matched analysis. Results: In total, 446 patients were included, and symptomatic GB disease was found in 62 patients (13.9%, 76.2/1000 ECMO days). Complicated GB disease occurred in 42 patients (9.4%, 89.4/1000 ECMO days) and presented as acute cholecystitis, acute cholangitis, and biliary pancreatitis in 33 (7.4%), 7 (1.6%), and 5 (1.1%) patients, respectively. In multivariate Cox regression analysis, longer ECMO support (>2 weeks) (hazard ratio (HR), 2.95; 95% confidence interval (CI), 1.69−5.15) and elevated plasma hemoglobin (Hb, >50 mg/dL) (HR. 2.12; 95% CI, 1.18−3.78) were significantly associated with the development of GB disease. In the propensity-matched cohort, the intensive care unit (ICU) and hospital survival rates were significantly lower for patients with GB disease than for those without GB disease (ICU survival rate, 64.5% vs. 84.7%; hospital survival rate, 59.7% vs. 81.5%). Conclusion: The incidence of GB disease was higher in patients who received ECMO than in the general ICU patients. Furthermore, elevated plasma Hb and prolonged ECMO therapy were significant factors for the development of GB disease during ECMO therapy.

Post-Discharge Depression Status for Survivors of Extracorporeal Membrane Oxygenation (ECMO): Comparison of Veno-Venous ECMO and Veno-Arterial ECMO

Extracorporeal membrane oxygenation (ECMO) is one of the common invasive treatments for the care of critically ill patients with heart failure, respiratory failure, or both. There are two modes of ECMO, namely, veno-venous (VV) and veno-arterial (VA), which have different indications, survival rates, and incidences of complications. This study’s aim was to examine whether depression status differed between patients who had received VV-ECMO or VA-ECMO and had been discharged from the hospital. This was a descriptive, cross-sectional, and correlational study of patients who had been discharged from the hospital at least one month after receiving ECMO at a medical center in northern Taiwan from June 2006 to June 2020 (N = 142). Participants were recruited via convenience and quota sampling. Data were collected in the cardiovascular outpatient department between October 2015–October 2016 (n = 52) and September 2019–August 2020 (n = 90). Participants completed the Hospital Anxiety and Depression Scale–Depression (HADS-D) as a measure of depression status. Post-discharge depression scores for patients who received VV-ECMO (n = 67) was significantly higher (p = 0.018) compared with participants who received VA-ECMO (n = 75). In addition, the mode of ECMO was a predictor of post-discharge depression (p = 0.008) for participants who received VV-ECMO. This study concluded that patients who received VV-ECMO may require greater mental health support. Healthcare professionals should establish a psychological clinical care pathway evaluated by multiple healthcare professionals.

Pulmonary Artery Pulsatility Index and Hemolysis during Impella-Incorporated Mechanical Circulatory Support

Background: Impella is a percutaneous transcatheter left ventricular assist device. Device-related hemolysis is a serious complication that is sometimes encountered depending on the device position, device speed, and support duration. However, the impact of hemodynamics on the occurrence of hemolysis remains unknown. In this study, we aimed to clarify the relationships between hemodynamics, especially right ventricular function, and the occurrence of hemolysis during Impella-incorporated mechanical circulatory support. Methods: Consecutive patients who received Impella (2.5, CP, and 5.0) support at our institute between March 2018 and July 2021 were retrospectively included. The relationships between the pulmonary artery pulsatility index (PAPi) immediately after Impella insertion and the occurrence of hemolysis were investigated. Results: Forty-two patients (median 71 years old, 60% men) were included. Hemolysis occurred in 20 patients (48%). A cutoff of PAPi to predict hemolysis was calculated as 1.3, with 80.0% sensitivity and 72.7% specificity. Lower PAPi (<1.3) significantly correlated with the occurrence of hemolysis with an odds ratio of 11.65 (95% confidence interval 1.58−85.98, p = 0.017), adjusted for other potential confounders. Survival discharge was significantly lower in patients with lower PAPi (<1.3) (50% vs. 86%, p = 0.019). Conclusions: The results of this study suggest that patients with right ventricular impairment indicated by lower PAPi following the initiation of Impella-incorporated mechanical circulatory support have a higher risk of hemolysis.

The Hemodynamics of Small Arterial Return Cannulae for Venoarterial Extracorporeal Membrane Oxygenation

BACKGROUND

Venoarterial extracorporeal membrane oxygenation (ECMO) provides mechanical support for critically ill patients with cardiogenic shock. Typically, the size of the arterial return cannula is chosen to maximize flow. However, smaller arterial cannulae may reduce cannula-related complications and be easier to insert. This in vitro study quantified the hemodynamic effect of different arterial return cannula sizes in a simulated acute heart failure patient.

METHODS

Baseline support levels were simulated with a 17 Fr arterial cannula in an ECMO circuit attached to a cardiovascular simulator with targeted partial (2.0 L/min ECMO flow, 60-65 mmHg mean aortic pressure - MAP) and targeted full ECMO support (3.5 L/min ECMO flow and 70-75 mmHg MAP). Return cannula size was varied (13-21 Fr), and hemodynamics were recorded while keeping ECMO pump speed constant and adjusting pump speed to restore desired support levels.

RESULTS

Minimal differences in hemodynamics were found between cannula sizes in partial support mode. A maximum pump speed change of +600 rpm was required to reach the support target and arterial cannula inlet pressure varied from 79 (21 Fr) to 224 mmHg (13 Fr). The 15 Fr arterial cannula could provide the target full ECMO support at the targeted hemodynamics; however, the 13 Fr cannula could not due to the high resistance associated with the small diameter.

CONCLUSIONS

A 15 Fr arterial return cannula provided targeted partial and full ECMO support to a simulated acute heart failure patient. Balancing reduced cannula size and ECMO support level may improve patient outcomes by reducing cannula-related adverse events.

Intraoperative Management of Adult Patients on Extracorporeal Membrane Oxygenation: An Expert Consensus Statement From the Society of Cardiovascular Anesthesiologists-Part I, Technical Aspects of Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is used to support patients with refractory cardiopulmonary failure. Given ECMO's increased use in adults and the fact that many ECMO patients are cared for by anesthesiologists, the Society of Cardiovascular Anesthesiologists ECMO working group created an expert consensus statement that is intended to help anesthesiologists manage adult ECMO patients who are cared for in the operating room. In the first part of this 2-part series, technical aspects of ECMO are discussed, and related expert consensus statements are provided.

Intraoperative Management of Adult Patients on Extracorporeal Membrane Oxygenation: an Expert Consensus Statement From the Society of Cardiovascular Anesthesiologists-Part I, Technical Aspects of Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is used to support patients with refractory cardiopulmonary failure. Given ECMO's increased use in adults and the fact that many ECMO patients are cared for by anesthesiologists, the Society of Cardiovascular Anesthesiologists ECMO working group created an expert consensus statement that is intended to help anesthesiologists manage adult ECMO patients who are cared for in the operating room. In the first part of this 2-part series, technical aspects of ECMO are discussed, and related expert consensus statements are provided.

Carboxyhemoglobin levels in children during extracorporeal membrane oxygenation support: a retrospective study

INTRODUCTION

Hemolysis is a common complication of extracorporeal membrane oxygenation (ECMO). There are few data on whether carboxyhemoglobin (COHb), a potential marker of hemolysis, are elevated during ECMO support.

METHODS

We conducted a single-center, retrospective study comparing peak COHb levels of children pre-, during, and post-ECMO from January 2017 to August 2020.

RESULTS

There were 154 ECMO runs in 147 children (154 PICU admissions) included in the study. The median age was 3.5 (IQR 0.2, 39.2) months. Veno-arterial ECMO was the predominant mode: 146/154 (94.8%). Eighty-seven children (56.5%) underwent cardiac surgery. Peak COHb levels during ECMO were statistically significantly higher compared to pre ECMO (COHb 1.8% (IQR 1.4, 2.6) vs COHb 1.2% (IQR 0.7, 1.7), p < 0.001) and post ECMO (COHb 1.6% (IQR 1.3, 2.2), p = 0.009). Children with COHb ⩾2% were younger and had longer duration of ECMO support. Plasma hemoglobin weakly correlated with COHb level (r = 0.14; p = 0.04).

CONCLUSIONS

Carboxyhemoglobin levels increased during ECMO support compared to the pre and post ECMO period. Younger age and longer ECMO duration were associated with COHb levels ⩾2%. Plasma hemoglobin weakly correlated with COHb level.

Extracorporeal Membrane Oxygenation-Induced Hemolysis: An In Vitro Study to Appraise Causative Factors

In vitro hemolysis testing is commonly used to determine hemocompatibility of ExtraCorporeal Membrane Oxygenation (ECMO). However, poor reproducibility remains a challenging problem, due to several unidentified influencing factors. The present study investigated potential factors, such as flow rates, the use of anticoagulants, and gender of blood donors, which could play a role in hemolysis. Fresh human whole blood was anticoagulated with either citrate (n = 6) or heparin (n = 12; 6 female and 6 male blood donors). Blood was then circulated for 360 min at 4 L/min or 1.5 L/min. Regardless of flow rate conditions, hemolysis remained unchanged over time in citrated blood, but significantly increased after 240 min circulation in heparinized blood (p ≤ 0.01). The ratio of the normalized index of hemolysis (NIH) of heparinized blood to citrated blood was 11.7-fold higher at 4 L/min and 16.5–fold higher at 1.5 L/min. The difference in hemolysis between 1.5 L/min and 4 L/min concurred with findings of previous literature. In addition, the ratio of NIH of male heparinized blood to female was 1.7-fold higher at 4 L/min and 2.2-fold higher at 1.5 L/min. Our preliminary results suggested that the choice of anticoagulant and blood donor gender could be critical factors in hemolysis studies, and should be taken into account to improve testing reliability during ECMO.

Hemodynamic evaluation and in vitro hemolysis evaluation of a novel centrifugal pump for extracorporeal membrane oxygenation

Background

The STM CP-24 I centrifugal pump is a newly developed centrifugal pump for extracorporeal membrane oxygenation equipment. This study aimed to combine hydraulic experiments, hemodynamic numerical simulations, and standard in vitro hemolysis experiments to investigate the comprehensive performance of this centrifugal pump.

Methods

In vitro experiments were first done to obtain the pressure-flow data of the centrifugal pump in its working range to evaluate its hydraulic performance. Next, the commonly used clinical working points were selected as boundary conditions, and a computational fluid dynamics method was applied to evaluate its hemodynamic performance. The blood pressure distribution, blood flow fields, and high-wall-shear-stress zones in the centrifugal pump were determined as indicators for hemodynamic evaluation. Finally, standard in vitro hemolysis experiments were performed to test the blood compatibility of this centrifugal pump (n=3 blood samples). In addition, its blood compatibility was evaluated in the form of the normalized index of hemolysis (NIH).

Results

The pressure-flow curve of the centrifugal pump showed that the head pressure and flow of the centrifugal pump showed a mostly linear relationship within the whole working range. When the rotation speed of the centrifugal pump was 5,500 rpm, it achieved a hydraulic performance of 550 mmHg head pressure and 8 L/min output flow, which could meet the clinical needs of extracorporeal membrane oxygenation. Analysis of computational fluid dynamics data indicated that the centrifugal pump had excellent hemodynamic performance: even distribution of blood pressure in the pump, no blood flow stagnation zone or dead zone in the overall flow field, and secondary flows in the gap between the rotor and the volute that significantly reduced the volume of the low-blood-flow zone close to the impeller. There was no obvious high-shear-stress zone on the surface of the volute or the impeller, which will effectively reduce the risk of thrombosis. In vitro hemolysis experiments indicated that the centrifugal pump had excellent blood biocompatibility, with a NIH =0.0125±0.0022 g/100 L.

Conclusions

The STM CP-24 I centrifugal pump has excellent hydraulic performance, a reasonable design of the hemodynamic structure of the blood pump, and excellent blood compatibility. Therefore, it can meet clinical needs.

Thrombotic circuit complications during venovenous extracorporeal membrane oxygenation in COVID-19

The novel coronavirus SARS-CoV-2 and the resulting disease COVID-19 causes pulmonary failure including severe courses requiring venovenous extracorporeal membrane oxygenation (V-V ECMO). Coagulopathy is a known complication of COVID-19 leading to thrombotic events including pulmonary embolism. It is unclear if the coagulopathy also increases thrombotic circuit complications of the ECMO. Aim of the present study therefor was to investigate the rate of V-V ECMO complications in COVID-19. We conducted a retrospective registry study including all patients on V-V ECMO treated at our centre between 01/2018 and 04/2020. COVID-19 cases were compared non- COVID-19 cases. All circuit related complications resulting in partial or complete exchange of the extracorporeal system were registered. In total, 66 patients were analysed of which 11 (16.7%) were SARS-CoV-2 positive. The two groups did not differ in clinical parameters including age (COVID-19 59.4 vs. non-COVID-19 58.1 years), gender (36.4% vs. 40%), BMI (27.8 vs. 24.2) and severity of illness as quantified by the RESP Score (1pt. vs 1pt.). 28 days survival was similar in both groups (72.7% vs. 58.2%). While anticoagulation was similar in both groups (p = 0.09), centrifugal pump head thrombosis was more frequent in COVID-19 (9/11 versus 16/55 p < 0.01). Neither the time to first exchange (p = 0.61) nor blood flow at exchange (p = 0.68) did differ in both groups. D-dimer levels prior to the thrombotic events were significantly higher in COVID-19 (mean 15.48 vs 26.59, p = 0.01). The SARS-CoV-2 induced infection is associated with higher rates of thrombotic events of the extracorporeal system during V-V ECMO therapy.

The Prolonged Use of VV ECMO Support in COVID-19: A Case Report

COVID-19 has resulted in unprecedented global health and economic challenges. The reported mortality in patients with COVID-19 requiring mechanical ventilation is high. VV ECMO may serve as a lifesaving rescue therapy for a minority of patients with COVID-19; however, its impact on overall survival of these patients is unknown. To date, few reports describe successful discharge from ECMO in COVID-19 after a prolonged ECMO run. The only Australian case of a COVID-19 patient, supported by prolonged VV ECMO in conjunction with prone ventilation, complicated by significant airway bleeding, and successfully decannulated after forty-two days, is described. VV ECMO is a resource-intense form of respiratory support. Providing complex therapies such as VV ECMO during a pandemic has its unique challenges. This case report provides a unique insight into the potential clinical sequelae of COVID-19, supported in an intensive care environment which was not resource-limited at the time, and adds to the evolving experience of prolonged VV ECMO support for ARDS with a goal to lung recovery.

Case Report First-in-Man Method Description: Left Ventricular Unloading With iVAC2L During Veno-Arterial Extracorporeal Membrane Oxygenation: From Veno-Arterial Extracorporeal Membrane Oxygenation to ECMELLA to EC-iVAC®

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly used in bi-ventricular failure with cardiogenic shock to maintain systemic perfusion. Nonetheless, it tends to increase left ventricular (LV) afterload and myocardial oxygen demand. In order to mitigate these negative effects on the myocardium, an Impella CP® (3.5 L/min Cardiac Output) can be used in conjunction with V-A ECMO (ECMELLA approach). We implemented this strategy in a patient with severe acute myocarditis complicated by cardiogenic shock. Due to a hemolysis crisis, Impella CP® had to be substituted with PulseCath iVAC2L®, which applies pulsatile flow to unload the LV. A subsequent improvement in LV systolic function was noted, with increased LV ejection fraction (LVEF), LV end-diastolic diameter (LVEDD) reduction, and a reduction in plasma free hemoglobin. This case documents the efficacy of iVAC2L in replacing Impella CP as a LV vent during V-A ECMO, with less hemolysis.

Efficacy of Plasma free Hemoglobin for detecting centrifugal pump thrombosis

INTRODUCTION

Lactate dehydrogenase (LDH) is widely used as an indicator of pump thrombosis in a centrifugal pump. However, due to the low specificity of LDH, pump thrombosis is difficult to detect in the clinical environment. We measured plasma free hemoglobin (pfHb) with the portable device in ICU. The goal of this investigation is to evaluate its diagnostic ability for pump thrombosis.

METHODS

We enrolled 31 consecutive patients who needed Extracorporeal Membrane Oxygenation (ECMO) therapy and pfHb was determined with HemoCue^® plasma/Low Hb photometer. Pump thrombosis was analyzed macroscopically at the timing of pump explantation or exchange. Also, we divided the pump thrombosis into a grading scale by the place of thrombosis.

RESULTS

The median of peak pfHb was significantly lower in the none thrombus group (0.03 g/dL) than that of in the thrombus group (0.05g/dL) (p = 0.01). In our grading criteria, pfHb was significantly higher when the thrombus is existing near the shaft (p = 0.015). Contrary, no significant difference was found for LDH.The ROC analysis of pfHb revealed an AUC of 0.77 for detecting pump thrombosis with the best statistical cutoff value at 0.05 g/dL (specificity, 78%; sensitivity, 77%). Also, ROC analysis of LDH was performed (AUC, 0.44; cutoff value, 1200 IU/L; specificity, 59%; sensitivity, 54%) and compared with pfHb. AUC was significantly higher in pfHb (p = 0.04).

CONCLUSION

Our results showed the efficacy of pfHb for detecting centrifugal pump thrombosis.