Venovenous Extracorporeal Membrane Oxygenation Research Articles

Long-Term Clinical Outcomes of Acute Kidney Disease in Patients Receiving Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is widely used; however, studies on the long-term outcomes of ECMO are scarce. We investigated the long-term clinical outcomes of acute kidney disease (AKD) in patients receiving ECMO. Electronic data (2009-2018) were retrospectively collected from a multicenter database. Patients were divided into two groups (AKD and non-AKD) according to their AKD status 8-90 days after the initiation of ECMO. Inverse probability of treatment weighting (IPTW) was used to balance baseline covariates between the two groups. The primary outcomes were major adverse kidney events (MAKEs) and major adverse cardiovascular events (MACEs), and the secondary outcomes were all-cause readmission, sepsis-related readmission, infection-related readmission, and dementia. Total 395 patients were eligible for analysis; of them, 160 patients (40.5%) developed AKD. The AKD group had a higher risk of MAKEs (hazard ratio [HR]: 2.06; 95% confidence interval [CI]: 1.68-2.53) than did the non-AKD group. Subgroup analysis revealed that the observed unfavorable effect of AKD on the risk of MAKEs was more pronounced in patients receiving venovenous ECMO than in those receiving venoarterial ECMO (HR: 5.69 vs. 1.85, respectively; P for interaction = 0.004). AKD group had a higher risk of MACE during the initial 3-year post- ECMO in comparison to those without (HR: 1.68; 95% CI: 1.22-2.30). Moreover, the risks of all-cause, sepsis-related, and infection-related readmissions were high in AKD survivors. AKD is associated with an increased risk of long-term MAKEs and initial 3-year MACE in ECMO recipients. In addition, AKD is associated with increased risks of all-cause, infection-related, and sepsis-related readmissions.

Thermodilution-derived Recirculation and Cardiac Output Measurement during Veno-venous Extracorporeal Membrane Oxygenation: Do We Need More Bells and Whistles?

Thermodilution-derived Recirculation and Cardiac Output Measurement during Veno-venous Extracorporeal Membrane Oxygenation: Do We Need More Bells and Whistles?

Echocardiographic and Point-of-Care Ultrasonography (POCUS) Guidance in the Management of the ECMO Patient

Veno-arterial (V-A) and Veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) support is increasingly utilized for acute cardiogenic shock and/or respiratory failure. Echocardiography and point-of-care ultrasonography (POCUS) play a critical role in the selection and management of these critically ill patients, however, there are limited guidelines regarding their application. This comprehensive review describes current and potential application of echocardiography and POCUS for pre-ECMO assessment and patient selection, cannulation guidance with emphasis on dual-lumen configurations, diagnosis of ECMO complications and trouble-shooting of cannula malposition, diagnosis of common cardiac or pulmonary pathologies, and assessment of ECMO weaning appropriateness including identification of the aortic mixing point in V-A ECMO.

[Pregnant women with COVID-19 ARDS on the intensive care unit].

Pregnant women with coronavirus disease 2019 (COVID-19) are at increased risk of severe disease progression. Comorbidities, such as chronic arterial hypertension, diabetes mellitus, advanced maternal age and high body mass index, may predispose to severe disease. The management of pregnant COVID-19patients on the intensive care unit (ICU) is challenging and requires careful consideration of maternal, fetal and ethical issues. Description and discussion of intensive care treatment strategies and perinatal anesthesiological management in patients with COVID-19 acute respiratory distress syndrome (CARDS). We analyzed the demographic data, maternal medical history, clinical intensive care management, complications, indications and management of extracorporeal membrane oxygenation (ECMO) and infant survival of all pregnant patients treated for severe CARDS in the anesthesiological ICU of aGerman university hospital between March and November 2021. The cohort included 9 patients with amean age of 30.3 years (range 26-40years). The gestational age ranged from 21 + 3 weeks to 37 + 2 weeks. None of the patients had been vaccinated against SARS-CoV‑2. Of the nine patients seven were immigrants and communication was hampered by inadequate Central European language skills. Of the patients five had aPaO2/FiO2 index < 150 mm Hg despite escalated invasive ventilation (FiO2 > 0.9 and a positive end-expiratory pressure [PEEP] of 14 mbar) and were therefore treated with repeated prolonged prone positioning maneuvers (5-14 prone positions for 16 h each, atotal of 47prone positioning treatments) and 2 required treatment with inhaled nitric oxide and venovenous ECMO. The most common complications were bacterial superinfection of the lungs, urinary tract infection and delirium. All the women and five neonates survived. All newborns were delivered by cesarean section, two patients were discharged home with an intact pregnancy and two intrauterine fetal deaths were observed. None of the newborns tested positive for SARS-CoV‑2 at birth. High survival rates are possible in pregnant patients with CARDS. The peripartum management of pregnant women with CARDS requires close interdisciplinary collaboration and should prioritize maternal survival in early pregnancy. In our experience, prolonged prone positioning, an essential evidence-based cornerstone in the treatment of ARDS, can also be safely used in advanced stages of pregnancy. Inhaled nitric oxide (iNO) and ECMO should be considered as life-saving treatment options for carefully selected patients. For cesarean section, neuraxial anesthesia can be safely performed in patients with mild CARDS if well planned but the therapeutic anticoagulation recommended for COVID-19 may increase the risk of bleeding complications, making general anesthesia amore viable alternative, especially in severe disease.

Refractory cor pulmonale under extracorporeal membrane oxygenation for acute respiratory distress syndrome: the role of conversion to veno-pulmonary arterial assist—a case series

IntroductionPulmonary vascular dysfunction during severe acute respiratory distress syndrome (ARDS) may lead to right ventricle (RV) dysfunction and acute cor pulmonale (ACP). The occurrence/persistence of ACP despite conventional extracorporeal membrane oxygenation (ECMO) is a challenging situation. We explored the usefulness of a specific dual-lumen cannula that bypasses the RV, and on which a veno-pulmonary arterial assist (V-P ECMO) was mounted, in ARDS patients.MethodsWe report a case-series of ARDS patients put on conventional veno-arterial or veno-venous ECMO and presented refractory ACP as an indication for a reconfiguration to V-P ECMO using the ProtekDuo cannula. The primary endpoint was the mitigation of RV and pulmonary vascular dysfunction as assessed by the change in end-diastolic RV/left ventricle (LV) surface ratio.ResultsSix patients had their conventional ECMO reconfigured to V-P ECMO to treat refractory ACP. There was a decrease in end-diastolic RV/LV surface ratio, as well as end-systolic LV eccentricity index, and lactatemia immediately after V-P ECMO initiation. The resolution of refractory ACP was immediately achieved in four of our six (66%) patients. The V-P ECMO was weaned after a median of 26 [8–93] days after implantation. All but one patient were discharged home. We detected one case of severe hemolysis with V-P ECMO and two suspected cases of right-sided infective endocarditis.ConclusionV-P ECMO is useful to mitigate RV overload and to improve hemodynamics in case of refractory ACP despite conventional ECMO.

Extracorporeal membrane oxygenation versus invasive ventilation in patients with COVID-19 acute respiratory distress syndrome and pneumomediastinum: A cohort trial.

Patients with severe respiratory failure due to COVID-19 who are not under mechanical ventilation may develop severe hypoxemia when complicated with spontaneous pneumomediastinum (PM). These patients may be harmed by invasive ventilation. Alternatively, veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) may be applied. We report on the efficacy of V-V ECMO and invasive ventilation as initial advanced respiratory support in patients with COVID-19 and acute respiratory failure due to spontaneous PM. This was a retrospective cohort study performed between March 2020 and January 2022. Enrolled patients had COVID-19 and acute respiratory failure due to spontaneous PM and were not invasively ventilated. Patients were treated in the intensive care unit (ICU) with invasive ventilation (invasive ventilation group) or V-V ECMO support (V-V ECMO group) as the main therapeutic option. The primary outcomes were mortality and ICU discharge at 90 days after ICU admission. Twenty-two patients were included in this study (invasive ventilation group: 13 [59%]; V-V ECMO group: 9 [41%]). The V-V ECMO strategy was significantly associated with lower mortality (hazard ratio [HR] 0.33 [95% CI 0.12-0.97], p = 0.04). Five (38%) patients in the V-V ECMO group were intubated and eight (89%) patients in the invasive ventilation group required V-V ECMO support within 30 days from ICU admission. Three (33%) patients in the V-V ECMO group were discharged from ICU within 90 days compared to one (8%) patient in the invasive ventilation group (HR 4.71 [95% CI 0.48-45.3], p = 0.18). Preliminary data suggest that V-V ECMO without invasive ventilation may improve survival in COVID-19-related acute respiratory failure due to spontaneous PM. The study's retrospective design and limited sample size underscore the necessity for additional investigation and warrant caution.

Awake venovenous extracorporeal membrane oxygenation and survival

ObjectivesDeep sedation on the ICU is linked to poor outcome. This study investigated the link between Richmond Agitation-Sedation Scale (RASS) and outcome in venovenous extracorporeal membrane oxygenation (V-V ECMO).MethodsWe performed a secondary analysis of a single-center V-V ECMO cohort. RASS was used as a surrogate measure of sedation depth, patients with a score ≥ −1 were considered awake. V-V ECMO durations below 24 h were excluded. Primary endpoint was 30-day survival. Secondary endpoints were hospital survival and weaning from both ventilator and ECMO therapy.ResultsA total of 343 patients were reanalyzed. The median age was 55 years and 52.2% (179/343) survived for 30 days after ECMO cannulation. Median duration of ECMO was 7.9 (4.7–15.0) days and the median duration of mechanical ventilation after ECMO cannulation was 11.8 (6.7–23.8) days.In the whole cohort, median RASS on day one and seven after ECMO were − 4 (−4 to −1) and − 3 (−4 to 0), respectively. ECMO survivors consistently had significantly higher RASS scores during the first 7 days of ECMO compared to non-surviving patients (p &amp;lt; 0.01). On day two after ECMO, survival of awake patients (i.e., RASS ≥-1) was significantly better compared to sedated [i.e., RASS −4 to −2; OR 2.20 (1.28–3.71), p &amp;lt; 0.01] or unresponsive patients [i.e., RASS -5; OR 2.27 (1.15–4.64), p = 0.02]. The survival benefit of awake ECMO was consistent from day two to seven. Patients awake at least once during ECMO showed higher 30-day survival rates [64.4% vs. 39.6%, OR 2.75 (1.77–4.24), p &amp;lt; 0.01].ConclusionIn this retrospective study, awake patients on V-V ECMO showed higher 30-day survival rates compared to sedated or unresponsive patients. These data should encourage further research on awake V-V ECMO.

Predictive value of microcirculation for pediatric extracorporeal membrane oxygenation weaning test: Amonocentric prospective observational study.

Extracorporeal membrane oxygenation (ECMO) is widely used for children treated for refractory respiratory failures or refractory cardiogenic shock. Its duration depends on organ functions recovery. Weaning is decided using macro-circulatory tools, but microcirculation is not well evaluated. Sidestream dark-field video imaging is used to assess the perfusion of the sublingual microvascular vessels. The aim of this study was to assess the predictive value of microcirculatory indices in ECMO weaning. This prospective monocentric study examined pediatric patients at Trousseau Hospital between March 2017 and December 2020. The study included all patients from 35 weeks of gestational age to 18 years old who were treated with ECMO. Children were divided into two groups: one with stability after weaning and the other with instability after weaning. We collected clinical and biological data, ventilation parameters, extracorporeal membrane oxygenation parameters, and drugs used at admission and after the weaning test. Microcirculations videos were taken after weaning trials with echocardiography and blood gas monitoring. The study included 30 patients with a median age of 29 days (range: 1-770 days) at admission, including 18 patients who received venoarterial ECMO (60%). There were 19 children in the stability group and 11 in the instability group. Macrocirculatory and microcirculatory indices showed no differences between groups. The microvascular flow index was subnormal in both groups (2.3 (1.8-2.4) and 2.3 (2.3-2.6), respectively; p = 0.24). The microvascular indices were similar between cases of venovenous and venoarterial ECMO and between age groups. Microcirculation monitoring at the weaning phase did not predict the failure of ECMO weaning.

The impact of small movements with dual lumen cannulae during venovenous extracorporeal membrane oxygenation: A computational fluid dynamics analysis

Background and objectivesVenovenous Extracorporeal Membrane Oxygenation (VV ECMO) provides respiratory support to patients with severe lung disease failing conventional medical therapy. An essential component of the ECMO circuit are the cannulas, which drain and return blood into the body. Despite being anchored to the patient to prevent accidental removal, minor cannula movements are common during ECMO. The clinical and haemodynamic consequences of these small movements are currently unclear. This study investigated the risk of thrombosis and recirculation caused by small movements of a dual lumen cannula (DLC) in an adult using computational fluid dynamics. MethodsThe 3D model of an AVALON Elite DLC (27 Fr) and a patient-specific vena cava and right atrium were generated for an adult patient on ECMO. The baseline cannula position was generated where the return jet enters the tricuspid valve. Alternative cannula positions were obtained by shifting the cannula 5 and 15 mm towards inferior (IVC) and superior (SVC) vena cava, respectively. ECMO settings of 4 L/min blood flow and pulsatile flow at SVC and IVC were applied. Recirculation was defined as a scalar value indicating the infused oxygenated blood inside the drainage lumen, while thrombosis risk was evaluated by shear stress, stagnation volume, washout, and turbulent kinetic energy. ResultsRecirculation for all models was less than 3.1 %. DLC movements between -5 to 15 mm increased shear stress and turbulence kinetic energy up to 24.7 % and 11.8 %, respectively, compared to the baseline cannula position leading to a higher predicted thrombosis risk. All models obtained a complete washout after nine seconds except for when the cannula migrated 15 mm into the SVC, indicating persisting stasis and circulating zones. ConclusionIn conclusion, small DLC movements were not associated with an increased risk of recirculation. However, they may increase the risk of thrombosis due to increased shear rate, turbulence, and slower washout of blood. Developing effective cannula securement devices may reduce this risk.

A nomogram for predicting mortality in patients with COVID-19-associated acute respiratory distress syndrome treated with veno-venous extracorporeal membrane oxygenation

A nomogram for predicting mortality in patients with COVID-19-associated acute respiratory distress syndrome treated with veno-venous extracorporeal membrane oxygenation

Injection Site Matters: A Comparative Analysis of Transpulmonary Thermodilution via Simultaneous Femoral and Jugular Indicator Injections under Veno-Venous Extracorporeal Membrane Oxygenation Therapy.

Background: The use of veno-venous extracorporeal membrane oxygenation (vv-ECMO) in acute lung failure has witnessed a notable increase. The PiCCO system is frequently used for advanced hemodynamic monitoring in this cohort. Our study aimed to investigate whether the choice of indicator injection site (jugular vs. femoral) in patients undergoing vv-ECMO therapy affects transpulmonary thermodilution (TPTD) measurements using the PiCCO® device (Pulsion Medical Systems SE, Munich, Germany). Methods: In a retrospective single-center analysis, we compared thermodilution-derived hemodynamic parameters after simultaneous jugular and femoral injections in 28 measurements obtained in two patients with respiratory failure who were undergoing vv-ECMO therapy. Results: Elevated values of the extravascular lung water index (EVLWI), intrathoracic blood volume index (ITBVI) and global end-diastolic volume index (GEDVI) were observed following femoral indicator injection compared to jugular indicator injection (EVLWI: 29.3 ± 10.9 mL/kg vs. 18.3 ± 6.71 mL/kg, p = 0.0003; ITBVI: 2163 ± 631 mL/m2 vs. 806 ± 125 mL/m2, p < 0.0001; GEDVI: 1731 ± 505 mL/m2 vs. 687 ± 141 mL/m2, p < 0.0001). The discrepancy between femoral and jugular measurements exhibited a linear correlation with extracorporeal blood flow (ECBF). Conclusions: In a PiCCO®-derived hemodynamic assessment of patients on vv-ECMO, the femoral indicator injection, as opposed to the jugular injection, resulted in an overestimation of all index parameters. This discrepancy can be attributed to mean transit time (MTt) and downslope time-dependent (DSt) variations in GEDVI and cardiac function index and is correlated with ECBF.

Novel Non-surgical Strategy of Severe Chest Trauma With Venovenous Extracorporeal Membrane Oxygenation, Angioembolization, and Bronchial Blocker: A Case Report

Novel Non-surgical Strategy of Severe Chest Trauma With Venovenous Extracorporeal Membrane Oxygenation, Angioembolization, and Bronchial Blocker: A Case Report

Alternative venous access sites for dual-lumen extracorporeal membrane oxygenation cannulation.

Dual-lumen cannulas for veno-venous (VV) extracorporeal membrane oxygenation (ECMO) support are typically inserted in the right internal jugular vein (RIJV), however some scenarios can make this venous route inaccessible. This multicentre case series aims to evaluate if single site cannulation using an alternative venous access is safe and feasible in patients with an inaccessible RIJV. We performed a multi-institutional retrospective analysis including high-volume ECMO centers with substantial experience in dual-lumen cannulation (DLC) (defined as > 10 DLC per year). Three centers ((Freiburg (Germany), Toronto (Canada) and Vienna (Austria)) agreed to share their data, including baseline characteristics, technical ECMO and cannulation data as well as complications related to ECMO cannulation and outcome. A total of 20 patients received alternative DLC for respiratory failure. Cannula insertion sites included the left internal jugular vein (n = 5), the right (n = 7) or left (n = 3) subclavian vein and the right (n = 4) or left (n = 1) femoral vein. Median cannula size was 26 (19-28) French. Median initial target ECMO flow was 2.9 (1.8-3.1) L/min and corresponded with used cannula size and estimated cardiac output. No procedural complications were reported during cannulation and median ECMO runtime was 15 (9-22) days. Ten patients were successfully bridged to lung transplantation (n = 5) or lung recovery (n = 5). Ten patients died during or after ECMO support. Alternative venous access sites for single site dual-lumen catheters are a safe and feasible option to provide VV-ECMO support to patients with inaccessible RIJV.

Head-to-toe bedside ultrasound for adult patients on extracorporeal membrane oxygenation.

Bedside ultrasound represents a well-suited diagnostic and monitoring tool for patients on extracorporeal membrane oxygenation (ECMO) who may be too unstable for transport to other hospital areas for diagnostic tests. The role of ultrasound, however, starts even before ECMO initiation. Every patient considered for ECMO should have a thorough ultrasonographic assessment of cardiac and valvular function, as well as vascular anatomy without delaying ECMO cannulation. The role of pre-ECMO ultrasound is to confirm the indication for ECMO, identify clinical situations for which ECMO is not indicated, rule out contraindications, and inform the choice of ECMO configuration. During ECMO cannulation, the use of vascular and cardiac ultrasound reduces the risk of complications and ensures adequate cannula positioning. Ultrasound remains key for monitoring during ECMO support and troubleshooting ECMO complications. For instance, ultrasound is helpful in the assessment of drainage insufficiency, hemodynamic instability, biventricular function, persistent hypoxemia, and recirculation on venovenous (VV) ECMO. Lung ultrasound can be used to monitor signs of recovery on VV ECMO. Brain ultrasound provides valuable diagnostic and prognostic information on ECMO. Echocardiography is essential in the assessment of readiness for liberation from venoarterial (VA) ECMO. Lastly, post decannulation ultrasound mainly aims at identifying post decannulation thrombosis and vascular complications. This review will cover the role of head-to-toe ultrasound for the management of adult ECMO patients from decision to initiate ECMO to the post decannulation phase.

Dysphagia in COVID-19 Patients on Extracorporeal Membrane Oxygenation.

Patients on extracorporeal membrane oxygenation (ECMO) are infrequently nourished via oral feeding due to aspiration risks. Patients with COVID-19 and on ECMO represent a subpopulation that has additional factors that may affect their swallow function. This study aimed to describe the swallow function and ability to maintain oral feeding in patients with COVID-19 while on ECMO. A retrospective study of patients with COVID-19 who started veno-venous ECMO at the beginning of the COVID-19 pandemic (March 2020 and August 2020) was conducted at a tertiary care hospital. Clinical swallow evaluations and videofluoroscopic swallow studies (VFSS) were analyzed using standardized measurement scales. Pearson's correlation coefficient (r) identified relationships between ECMO and swallowing function at different time points. 19 patients were included; all underwent clinical swallow evaluation and 4 underwent VFSS while on ECMO. Mean age was 43.2 years (standard deviation: 9.2), mean duration of ECMO was 65.7 days (58.7), and mean duration of intubation was 14.4 days (8.6). All patients were able to undergo swallow function evaluation, regain swallow function, and resume oral feeding while cannulated. Duration of ECMO and time to feeding tube removal was positively correlated (r = 0.747, p < 0.001) with patients demonstrating less functional swallowing independence and requiring a more modified diet upon oral diet initiation. Clinical swallow evaluation and videofluoroscopic swallowing evaluation are possible for COVID-19 patients actively on ECMO. Patient swallow function can improve, and oral diet can be achieved while on ECMO, demonstrating benefit of SLP surveillance and swallowing assessment prior to ECMO decannulation.

Plasmapheresis as therapeutic option in a 16-year-old with EVALI: A case report.

Since 2019 when a cluster of cases with acute respiratory distress syndrome (ARDS) associated with e-cigarettes in the United States was reported, there have been increasing numbers of reports. Electronic-cigarette or Vaping Use-associated Lung Injury (EVALI) represents a recent entity of respiratory clinical syndromes, primarily in young adults. We report a previously healthy 16-year-old boy who developed severe ARDS following a brief nonspecific prodromal phase after excessive consumption of e-cigarettes. Despite maximum intensive care therapy, including several weeks of venovenous extracorporeal membrane oxygenation, plasmapheresis and repeated administration of immunoglobulins seemed the only way to achieve therapeutic success. Although many case reports have been published, to our knowledge, there are none to date on the therapeutic use of plasmaphoresis in severe EVALI. This case highlights the clinical features of EVALI and the diagnostic dilemma that can arise with EVALI occurring against the background of an expired SARS-CoV-2 infection, with a paediatric inflammatory syndrome (PIMS) as differential diagnosis. EVALI is a diagnosis of exclusion, and the medical history of vaping and e-cigarette use can provide valuable clues. Ethical approval for this case report (protocol number 23-145 RS) was provided by the Ethical Committee of the Department of Medicine, Philipps-Universität Marburg, Germany on 13th of June 2023. Written informed consent to publish this case and the associated images was obtained from the patient and his mother.

Occurrence, Predictors, and Management of Late Vascular Complications following Extracorporeal Membrane Oxygenation

BackgroundVascular complications (VC) associated with Extracorporeal Membrane Oxygenation (ECMO) during index hospitalization are prevalent and associated with increased mortality. Few studies have evaluated late VC following ECMO; this study aims to assess occurrence and management practices of late VC following discharge. MethodsA retrospective single-institution review was performed of all patients surviving initial hospitalization after being cannulated for central or peripheral veno-venous (VV) or veno-arterial (VA) ECMO between January 1st 2019 and December 31st 2020. Primary outcomes were to categorize and determine the rate late VC. Late VCs were defined as any cannulated vessel injury resulting from ECMO cannulation presenting after discharge from index hospitalization. Analysis was conducted by cannulated vessel and stratified by VV or VA ECMO configurations. ResultsA total of 229 patients were identified, of which 50.6% (n=116) survived until discharge. Late VC occurred in 7.8% of the surviving cohort (n=9/116); with a median time until presentation of 150 days (IQR 83-251). The most common late VC was infection (n=5, 55.6%) followed by progression to limb threatening ischemia (n=4, 44.4%). Urgent procedures were required in 55.6% of patients (n=5), while 44.4% (n=4) were elective interventions. Interventions performed for management of late VC included lower extremity arterial revascularization (n=6, 66.7%), major (n=1, 11.1%) or minor amputation (n=1, 11.1%), and wound debridement (n=1, 11.1%). The majority of patients presenting with late VC had initially been cannulated for peripheral-VA ECMO (n=8, 88.9%) and 1 patient (11.1%) was cannulated for peripheral-VV ECMO. VC during index hospitalization were seen in 77.8% (n=7) of patients returning with late VC. Odds for late VC were significantly increased in patients that had been cannulated for ECMO as part of extracorporeal-cardio-pulmonary resuscitation (E-CPR) (OR 8.4, p=0.016) and in cases were patient had experienced an index VC during index hospitalization (OR 19.3, p=0.001). ConclusionLate vascular complications after peripheral ECMO cannulation are not rare, particularly after arterial cannulation. Patients should be followed closely early after surviving ECMO with wound evaluation and formal assessment of perfusion with ankle-branchial indices in the cannulated limb.

Mechanical ventilation during extracorporeal membrane oxygenation support - New trends and continuing challenges.

The impact of mechanical ventilation on the survival of patients supported with veno-venous extracorporeal membrane oxygenation (V-V ECMO) due to severe acute respiratory distress syndrome (ARDS) remains still a focus of research. Recent guidelines, randomized trials, and registry data underscore the importance of lung-protective ventilation during respiratory and cardiac support on ECMO. This approach includes decreasing mechanical power delivery by reducing tidal volume and driving pressure as much as possible, using low or very low respiratory rate, and a personalized approach to positive-end expiratory pressure (PEEP) setting. Notably, the use of ECMO in awake and spontaneously breathing patients is increasing, especially as a bridging strategy to lung transplantation. During respiratory support in V-V ECMO, native lung function is of highest importance and adjustments of blood flow on ECMO, or ventilator settings significantly impact the gas exchange. These interactions are more complex in veno-arterial (V-A) ECMO configuration and cardiac support. The fraction on delivered oxygen in the sweep gas and sweep gas flow rate, blood flow per minute, and oxygenator efficiency have an impact on gas exchange on device side. On the patient side, native cardiac output, native lung function, carbon dioxide production (VCO2), and oxygen consumption (VO2) play a role. Avoiding pulmonary oedema includes left ventricle (LV) distension monitoring and prevention, pulse pressure >10mm Hg and aortic valve opening assessment, higher PEEP adjustment, use of vasodilators, ECMO flow adjustment according to the ejection fraction, moderate use of inotropes, diuretics, or venting strategies as indicated and according to local expertise and resources. Understanding the physiological principles of gas exchange during cardiac support on femoro-femoral V-A ECMO configuration and the interactions with native gas exchange and haemodynamics are essential for the safe applications of these techniques in clinical practice. Proning during ECMO remains to be discussed until further data is available from prospective, randomized trials implementing individualized PEEP titration during proning.

The intricate physiology of veno-venous extracorporeal membrane oxygenation: an overview for clinicians.

During veno-venous extracorporeal membrane oxygenation (V-V ECMO), blood is drained from the central venous circulation to be oxygenated and decarbonated by an artificial lung. It is then reinfused into the right heart and pulmonary circulation where further gas-exchange occurs. Each of these steps is characterized by a peculiar physiology that this manuscript analyses, with the aim of providing bedside tools for clinical care: we begin by describing the factors that affect the efficiency of blood drainage, such as patient and cannulae position, fluid status, cardiac output and ventilatory strategies. We then dig into the complexity of extracorporeal gas-exchange, with particular reference to the effects of extracorporeal blood-flow (ECBF), fraction of delivered oxygen (FdO2) and sweep gas-flow (SGF) on oxygenation and decarbonation. Subsequently, we focus on the reinfusion of arterialized blood into the right heart, highlighting the effects on recirculation and, more importantly, on right ventricular function. The importance and challenges of haemodynamic monitoring during V-V ECMO are also analysed. Finally, we detail the interdependence between extracorporeal circulation, native lung function and mechanical ventilation in providing adequate arterial blood gases while allowing lung rest. In the absence of evidence-based strategies to care for this particular group of patients, clinical practice is underpinned by a sound knowledge of the intricate physiology of V-V ECMO.

The role of inflammation and antithrombin supplementation on thromboelastographic parameters during veno-venous ECMO for respiratory failure.

Extracorporeal membrane oxygenation (ECMO) may act as a driver or propagator of systemic inflammation. In turn, cytokine release can modify thromboelastographic (TEG) tests which are commonly used for anticoagulation monitoring. In this context, antithrombin (AT) supplementation might further modify TEG. This is a pre-specified sub-study of the "Randomized Controlled Trial of Antithrombin Supplementation During Extracorporeal Membrane Oxygenation" study (investigator-initiated, randomized, single-blind, two-arm trial) conducted in two Italian ECMO referral ICUs. Adult patients requiring vv-ECMO for respiratory failure and undergoing unfractioned heparin (UFH) administration were enrolled and randomized whether to receive AT supplementation. Plasma samples for cytokine assay (IL-8, IL-10, IL-6, IL-1β, TNF-α and Pro-ADM) and heparinase TEG were collected from every patient before ECMO start, 24h and 72h after ECMO start, before ECMO removal, and 7days after ECMO removal or upon ICU discharge whichever happened first. AT concentration, coagulation and clinical data were collected before ECMO start and at pre-fixed time points. Thirty-nine patients were enrolled (21 treatments, 18 controls). TEG-R had a weak-to-moderate positive correlation with IL-8, IL-6, IL-10 and TNF-α and a moderate positive correlation with Pro-ADM. TEG-ANG showed a weak negative correlation with IL-8, IL-6 and TNF-α, while TEG-MA negatively correlated with IL-8, TNF-α and Pro-ADM. AT supplementation seemed to modify the association between TEG-MA and IL-8, IL-10 and Pro-ADM; conversely, AT did not affect the relationship among TEG-R or TEG-ANG and the studied cytokines. High concentrations of systemic cytokines correlated with longer reaction times and decreased angle and amplitude at TEG, suggesting that an increase in inflammation is related with hypocoagulability as revealed by thromboelastography.