A case of severe respiratory failure due to interstitial pneumonia successfully bridged to lung transplantation from a brain-dead donor using 109-day veno-arterial extracorporeal membrane oxygenation.

In Japan, successful cases of a bridge to lung transplantation (BTT) by extracorporeal membrane oxygenation (ECMO) are rare. We present the case of a man in his thirties, diagnosed with interstitial pneumonia 6 years prior and registered for lung transplant 1 year prior due to disease progression despite treatment. Due to the patient's worsening respiratory failure, he was transferred to our hospital for BTT by ECMO. Since long-term management was expected and pulmonary hypertension was present, veno-arterial (V-A) ECMO was conducted using the right atrial blood outflow via the right internal jugular vein and right axillary artery inflow via a vascular graft. After tracheostomy, he was managed as "Awake ECMO". In addition, interprofessional collaboration such as physiotherapist rehabilitation, nurses, and liaison teams prevented muscle weakness and supported the mental aspect. We were able to minimize complications such as severe infections and bleeding. A compatible brain-dead donor was found on day 108 after introducing ECMO, and the patient was transferred to a transplant facility on day 109. The peripheral upper V-A ECMO is one of the configurations suitable for long-term BTT management.

Early short course of neuromuscular blocking agents in patients with COVID-19 ARDS: a propensity score analysis.

BACKGROUND: The role of neuromuscular blocking agents (NMBAs) in coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome (ARDS) is not fully elucidated. Therefore, we aimed to investigate in COVID-19 patients with moderate-to-severe ARDS the impact of early use of NMBAs on 90-day mortality, through propensity score (PS) matching analysis. METHODS: We analyzed a convenience sample of patients with COVID-19 and moderate-to-severe ARDS, admitted to 244 intensive care units within the COVID-19 Critical Care Consortium, from February 1, 2020, through October 31, 2021. Patients undergoing at least 2 days and up to 3 consecutive days of NMBAs (NMBA treatment), within 48 h from commencement of IMV were compared with subjects who did not receive NMBAs or only upon commencement of IMV (control). The primary objective in the PS-matched cohort was comparison between groups in 90-day in-hospital mortality, assessed through Cox proportional hazard modeling. Secondary objectives were comparisons in the numbers of ventilator-free days (VFD) between day 1 and day 28 and between day 1 and 90 through competing risk regression. RESULTS: Data from 1953 patients were included. After propensity score matching, 210 cases from each group were well matched. In the PS-matched cohort, mean (± SD) age was 60.3 ± 13.2 years and 296 (70.5%) were male and the most common comorbidities were hypertension (56.9%), obesity (41.1%), and diabetes (30.0%). The unadjusted hazard ratio (HR) for death at 90 days in the NMBA treatment vs control group was 1.12 (95% CI 0.79, 1.59, p = 0.534). After adjustment for smoking habit and critical therapeutic covariates, the HR was 1.07 (95% CI 0.72, 1.61, p = 0.729). At 28 days, VFD were 16 (IQR 0-25) and 25 (IQR 7-26) in the NMBA treatment and control groups, respectively (sub-hazard ratio 0.82, 95% CI 0.67, 1.00, p = 0.055). At 90 days, VFD were 77 (IQR 0-87) and 87 (IQR 0-88) (sub-hazard ratio 0.86 (95% CI 0.69, 1.07; p = 0.177). CONCLUSIONS: In patients with COVID-19 and moderate-to-severe ARDS, short course of NMBA treatment, applied early, did not significantly improve 90-day mortality and VFD. In the absence of definitive data from clinical trials, NMBAs should be indicated cautiously in this setting.

Catheter-related thrombosis after cardiac surgery in patients with both central venous and pulmonary artery catheters inserted into the right internal jugular vein: a single-center, prospective, observational study.

Central venous catheters (CVCs) and pulmonary artery catheters (PACs) are widely used in intensive care and perioperative management. The detection and prevention of catheter-related thrombosis (CRT) are important because CRT is a complication of catheter use and can cause pulmonary embolism and bloodstream infection. Currently, there is no evidence for CRT in patients using both CVC and PAC. We conducted a single-center, prospective, observational study to identify the incidence, timing, and risk factors for CRT in patients undergoing cardiovascular surgery and using a combination of CVC and PAC through the right internal jugular vein (RIJV). Out of 50 patients, CRT was observed using ultrasonography in 39 patients (78%), and the median time of CRT formation was 1 day (interquartile range: 1-1.5) after catheter insertion. The mean duration of PAC placement was 3 days (interquartile range: 2-5), and the maximum diameter of CRT was 12 mm (interquartile range: 10-15). In short-axis images, CRT occupied more than half of the cross-sectional area of the RIJV in five patients (10%), and CRT completely occluded the RIJV in one patient (2%). Platelet count, duration of PAC placement, and intraoperative bleeding amount were found to be high-risk indicators of CRT. In conclusion, patients who underwent cardiovascular surgery and using both CVC and PAC had a high incidence of CRT. Avoiding unnecessary PAC placement and early removal of catheters in patients at high risk of developing CRT may prevent the development of CRT.

Establishment and evaluation of a rat model of extracorporeal membrane oxygenation (ECMO) thrombosis using a 3D-printed mock-oxygenator.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) research using large animals requires a significant amount of resources, slowing down the development of new means of ECMO anticoagulation. Therefore, this study developed and evaluated a new rat ECMO model using a 3D-printed mock-oxygenator. METHODS: The circuit consisted of tubing, a 3D-printed mock-oxygenator, and a roller pump. The mock-oxygenator was designed to simulate the geometry and blood flow patterns of the fiber bundle in full-scale oxygenators but with a low (2.5 mL) priming volume. Rats were placed on arteriovenous ECMO at a 1.9 mL/min flow rate at two different heparin doses (n = 3 each): low (15 IU/kg/h for eight hours) versus high (50 IU/kg/h for one hour followed by 25 IU/kg/h for seven hours). The experiment continued for eight hours or until the mock-oxygenator failed. The mock-oxygenator was considered to have failed when its blood flow resistance reached three times its baseline resistance. RESULTS: During ECMO, rats maintained near-normal mean arterial pressure and arterial blood gases with minimal hemodilution. The mock-oxygenator thrombus weight was significantly different (p < 0.05) between the low (0.02 ± 0.006 g) and high (0.003 ± 0.001 g) heparin delivery groups, and blood flow resistance was also larger in the low anticoagulation group. CONCLUSIONS: This model is a simple, inexpensive system for investigating new anticoagulation agents for ECMO and provides low and high levels of anticoagulation that can serve as control groups for future studies.

An appraisal of respiratory system compliance in mechanically ventilated covid-19 patients.

BACKGROUND: Heterogeneous respiratory system static compliance (CRS) values and levels of hypoxemia in patients with novel coronavirus disease (COVID-19) requiring mechanical ventilation have been reported in previous small-case series or studies conducted at a national level. METHODS: We designed a retrospective observational cohort study with rapid data gathering from the international COVID-19 Critical Care Consortium study to comprehensively describe CRS-calculated as: tidal volume/[airway plateau pressure-positive end-expiratory pressure (PEEP)]-and its association with ventilatory management and outcomes of COVID-19 patients on mechanical ventilation (MV), admitted to intensive care units (ICU) worldwide. RESULTS: We studied 745 patients from 22 countries, who required admission to the ICU and MV from January 14 to December 31, 2020, and presented at least one value of CRS within the first seven days of MV. Median (IQR) age was 62 (52-71), patients were predominantly males (68%) and from Europe/North and South America (88%). CRS, within 48 h from endotracheal intubation, was available in 649 patients and was neither associated with the duration from onset of symptoms to commencement of MV (p = 0.417) nor with PaO2/FiO2 (p = 0.100). Females presented lower CRS than males (95% CI of CRS difference between females-males: - 11.8 to - 7.4 mL/cmH2O p < 0.001), and although females presented higher body mass index (BMI), association of BMI with CRS was marginal (p = 0.139). Ventilatory management varied across CRS range, resulting in a significant association between CRS and driving pressure (estimated decrease - 0.31 cmH2O/L per mL/cmH20 of CRS, 95% CI - 0.48 to - 0.14, p < 0.001). Overall, 28-day ICU mortality, accounting for the competing risk of being discharged within the period, was 35.6% (SE 1.7). Cox proportional hazard analysis demonstrated that CRS (+ 10 mL/cm H2O) was only associated with being discharge from the ICU within 28 days (HR 1.14, 95% CI 1.02-1.28, p = 0.018). CONCLUSIONS: This multicentre report provides a comprehensive account of CRS in COVID-19 patients on MV. CRS measured within 48 h from commencement of MV has marginal predictive value for 28-day mortality, but was associated with being discharged from ICU within the same period. Trial documentation: Available at https://www.covid-critical.com/study . TRIAL REGISTRATION: ACTRN12620000421932.

Hospital survival outcomes in acute respiratory distress syndrome patients receiving veno-venous extracorporeal membrane oxygenation for longer than 28 days: A retrospective study.

The successful use of prolonged (ie, >28 days) veno-venous extracorporeal membrane oxygenation (V-V ECMO) is being increasingly reported. However, limited data are available on its outcomes. This study investigated the outcomes of acute respiratory distress syndrome (ARDS) patients on prolonged ECMO support. We retrospectively evaluated 57 patients requiring V-V ECMO for ARDS between 2015 and 2020. The patients were divided into two groups according to ECMO duration: (a) ≤28 days group (n = 43, 75%) or (b) >28 days (n = 14, 25%) group. Clinical characteristics, complications, and outcomes between these two groups were statistically compared. There were no significant differences in demographics, comorbidity, ARDS etiology, and severity scores between the two groups. However, the mechanical ventilation period before ECMO initiation was significantly longer in the >28 days group than in the ≤28 days group (10.5 days vs. 1 day; P < .05). The incidence of positive bacterial blood culture results during ECMO was significantly higher in the >28 days group than in the ≤28 days group (43% vs. 9%; P < .05). Additionally, the hospital survival rate was significantly lower in the >28 days group than in the ≤28 days ECMO group (21% vs. 60%; P < .05). Prolonged ECMO was associated with worse hospital survival outcomes. Early initiation of ECMO along with meticulous care and appropriate treatment against infection during ECMO could improve the hospital survival of ARDS patients on prolonged ECMO support.

Artificial lungs--Where are we going with the lung replacement therapy?

Lung transplantation may be a final destination therapy in lung failure, but limited donor organ availability creates a need for alternative management, including artificial lung technology. This invited review discusses ongoing developments and future research pathways for respiratory assist devices and tissue engineering to treat advanced and refractory lung disease. An overview is also given on the aftermath of the coronavirus disease 2019 pandemic and lessons learned as the world comes out of this situation. The first order of business in the future of lung support is solving the problems with existing mechanical devices. Interestingly, challenges identified during the early days of development persist today. These challenges include device-related infection, bleeding, thrombosis, cost, and patient quality of life. The main approaches of the future directions are to repair, restore, replace, or regenerate the lungs. Engineering improvements to hollow fiber membrane gas exchangers are enabling longer term wearable systems and can be used to bridge lung failure patients to transplantation. Progress in the development of microchannel-based devices has provided the concept of biomimetic devices that may even enable intracorporeal implantation. Tissue engineering and cell-based technologies have provided the concept of bioartificial lungs with properties similar to the native organ. Recent progress in artificial lung technologies includes continued advances in both engineering and biology. The final goal is to achieve a truly implantable and durable artificial lung that is applicable to destination therapy.

Factors Affecting the Absorption of Midazolam to the Extracorporeal Membrane Oxygenation Circuit.

Sedatives are administered during extracorporeal membrane oxygenation (ECMO) therapy to ensure patient safety, reduce the metabolic rate and correct the oxygen supply-demand balance. However, the concentrations of sedatives can be decreased due to absorption into the circuit. This study examined factors affecting the absorption of a commonly used sedative, midazolam (MDZ). Using multiple ex vivo simulation models, three factors that may influence MDZ levels in the ECMO circuit were examined: polyvinyl chloride (PVC) tubing in the circuit, use of a membrane oxygenator in the circuit, and heparin coating of the circuit. We also assessed changes in drug concentration when MDZ was re-injected in a circuit. The MDZ level decreased to approximately 60% of the initial concentration in simulated circuits within the first 30 minutes. The strongest factor in this phenomenon was contact with the PVC tubing. Membrane oxygenator use tended to increase MDZ loss, whereas heparin circuit coating had no influence on MDZ absorption. Similar results were obtained when a second dose of MDZ was injected to the second-use circuits.

[Successful lung transplantation after long-term ventilator and extracorporeal membrane oxygenation support in a patient with severe bronchiolitis obliterans following allogeneic bone marrow transplantation].

A 29-year-old man was diagnosed with acute myeloid leukemia at 20 years of age; he achieved a second complete remission at 22 years of age after an allogeneic unrelated bone marrow transplantation. After 14 months, he developed bronchiolitis obliterans (BO) due to chronic graft-versus-host disease. Home ventilator management was continuously performed for 3 years, but the patient required extracorporeal membrane oxygenation (ECMO) after progression to type 2 respiratory failure. A matched brain-dead lung donor was found after 5 months of intensive care management on ECMO, and bilateral lung transplantation was successfully performed. BO is a progressive refractory respiratory disease with poor prognosis. Careful management of infection, monitoring organ function, and lung transplantation at the appropriate time of initiation of mechanical ventilation or ECMO may save a patient's life. However, it is crucial to collaborate with higher education institutions or medical professionals in other departments.

Effect of the Pulsatile Extracorporeal Membrane Oxygenation on Hemodynamic Energy and Systemic Microcirculation in a Piglet Model of Acute Cardiac Failure.

The objective of this study was to compare the effects of pulsatile and nonpulsatile extracorporeal membrane oxygenation (ECMO) on hemodynamic energy and systemic microcirculation in an acute cardiac failure model in piglets. Fourteen piglets with a mean body weight of 6.08 ± 0.86 kg were divided into pulsatile (N = 7) and nonpulsatile (N = 7) ECMO groups. The experimental ECMO circuit consisted of a centrifugal pump, a membrane oxygenator, and a pneumatic pulsatile flow generator system developed in-house. Nonpulsatile ECMO was initiated at a flow rate of 140 mL/kg/min for the first 30 min with normal heart beating, with rectal temperature maintained at 36°C. Ventricular fibrillation was then induced with a 3.5-V alternating current to generate a cardiac dysfunction model. Using this model, we collected the data on pulsatile and nonpulsatile groups. The piglets were weaned off ECMO at the end of the experiment (180 min after ECMO was initiated). The animals did not receive blood transfusions, inotropic drugs, or vasoactive drugs. Blood samples were collected to measure hemoglobin, methemoglobin, blood gases, electrolytes, and lactic acid levels. Hemodynamic energy was calculated using the Shepard's energy equivalent pressure. Near-infrared spectroscopy was used to monitor brain and kidney perfusion. The pulsatile ECMO group had a higher atrial pressure (systolic and mean), and significantly higher regional saturation at the brain level, than the nonpulsatile group (for both, P < 0.05). Additionally, the pulsatile ECMO group had higher methemoglobin levels within the normal range than the nonpulsatile group. Our study demonstrated that pulsatile ECMO produces significantly higher hemodynamic energy and improves systemic microcirculation, compared with nonpulsatile ECMO in acute cardiac failure.

A prospective randomized trial comparing the clinical effectiveness and biocompatibility of heparin-coated circuits and PMEA-coated circuits in pediatric cardiopulmonary bypass.

OBJECT: We compared the clinical effectiveness and biocompatibility of poly-2-methoxyethyl acrylate (PMEA)-coated and heparin-coated cardiopulmonary bypass (CPB) circuits in a prospective pediatric trial. METHODS: Infants randomly received heparin-coated (n=7) or PMEA-coated (n=7) circuits in elective pediatric cardiac surgery with CPB for ventricular septum defects. Clinical and hematologic variables, respiratory indices and hemodynamic changes were analyzed perioperatively. RESULTS: Demographic and clinical variables were similar in both groups. Leukocyte counts were significantly lower 5 minutes after CPB in the PMEA group than the heparin group. Hemodynamic data showed that PMEA caused hypotension within 5 minutes of CPB. The respiratory index was significantly higher immediately after CPB and 1 hour after transfer to the intensive care unit (ICU) in the PMEA group, as were levels of C-reactive protein 24 hours after transfer to the ICU. CONCLUSION: Our study shows that PMEA-coated circuits, unlike heparin-coated circuits, cause transient leukopenia during pediatric CPB and, perhaps, systemic inflammatory respiratory syndrome after pediatric CPB.

Conditions and procedures for in-hospital extracorporeal life support (ECLS) in cardiopulmonary resuscitation (CPR) of adult patients.

The use of extracorporeal life support (ECLS) in cardiopulmonary resuscitation (CPR; ECPR) has been repeatedly published as non-randomized studies, mainly case series and case reports. The aim of this article is to support physicians, perfusionists, nurses and extracorporeal membrane oxygenation (ECMO) specialists who regularly perform ECPR or are willing to start an ECPR program by establishing standards for safe and efficient ECPR procedures. This article represents the experience and recommendations of physicians who provide ECPR routinely. Based on its survival and outcome rates, ECPR can be considered when determining the optimal treatment of patients who require CPR. The successful performance of ECLS cannulation during CPR is a life-saving measure and has been associated with improved outcome (including neurological outcome) after CPR. We summarize the general structure of an ECLS team and describe the cannulation procedure and the approaches for post-resuscitation care. The differences in hospital organizations and their regulations may result in variations of this model.

Acute respiratory distress syndrome in a child with severe epileptic disorder treated successfully by extracorporeal membrane oxygenation: a case report.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is now a candidate therapy for children with acute respiratory failure. CASE PRESENTATION: We report our experience of using central ECMO therapy for acute respiratory distress syndrome followed by seizure in a 15-month-old girl with a severe epileptic disorder. Her respiratory distress was refractory to standard medical treatment and mechanical ventilatory support. Her condition was complicated by development of a pneumothorax. The patient was successfully weaned off ECMO and discharged without deterioration of her neurological status. CONCLUSION: The successful outcome in this case resulted from the central ECMO, which enabled "lung rest" and adequate cerebral blood flow. In skilled ECMO facilities, early implementation of ECMO would give some advantages to patients such as the one presented here. Given the invasiveness and the ease of the procedure, introduction of dual-lumen catheters adequately sized for pediatric patients in Japan is required.

Prevalence, risk factors, and short-term consequences of traumatic brain injury-associated hyponatremia.

Hyponatremia, a common electrolyte disorder associated with traumatic brain injuries (TBIs), has high mortality and morbidity rates. The aim of this study was to identify the risk factors for hyponatremia associated with TBI. We retrospectively analyzed the cases of TBI patients who were admitted to the emergency intensive care unit at Okayama University Hospital between October 2011 and September 2014. A total of 82 TBI patients were enrolled. The incidences of hyponatremia (serum sodium level of＜135mEq/L) and severe hyponatremia (serum sodium level of＜130mEq/L) within the first 14 days after admission were 51% (n＝42) and 20% (n＝16), respectively. After admission, hyponatremia took a median period of 7 days to develop and lasted for a median of 3 days. Multivariate analysis demonstrated that higher fluid intake from days 1 to 3 and the presence of cranial fractures were risk factors for hyponatremia. The 58 patients with hyponatremia experienced fewer ventilator-free days, longer intensive care unit stays, and less favorable outcomes compared to the 24 patients without hyponatremia;however, these differences were not significant. Further studies are needed to determine the optimal management strategy for TBI-associated hyponatremia in the intensive care unit setting.

Mean lung pressure during adult high-frequency oscillatory ventilation: an experimental study using a lung model.

In adult high-frequency oscillatory ventilation (HFOV), stroke volume (SV) and mean lung pressure (PLung) are important for lung protection. We measured the airway pressure at the Y-piece and the lung pressure during HFOV using a lung model and HFOV ventilators for adults (R100 and 3100B). The lung model was made of a 20-liter, airtight rigid plastic container (adiabatic compliance: 19.3 ml/cmH2O) with or without a resistor (20 cmH2O/l/sec). The ventilator settings were as follows: mean airway pressure (MAP), 30 cmH2O; frequency, 5-15 Hz (every 1 Hz); airway pressure amplitude (AMP), maximum;and % of inspiratory time (IT), 50% for R100, 33% or 50% for 3100B. The measurements were also performed with an AMP of 2/3 or 1/3 maximum at 5, 10 and 15 Hz. The PLung and the measured MAP were not consistently identical to the setting MAP in either ventilator, and decreasing IT decreased the PLung in 3100B. In conclusion, we must pay attention to the possible discrepancy between the PLung and the setting MAP during adult HFOV.

Current Congenital Heart Surgery and Pediatric Perfusion Practices in Japan and Vietnam.

The declining birth rate and aging population are becoming increasingly serious social issues in Japan. In this report, we summarize the current congenital heart surgery and pediatric perfusion practices in Japan and Vietnam. In addition we report the rapid growth and development of congenital heart surgery in Vietnam made possible by medical education support provided by Japan over the past decade.

Pilot Testing of a Lightweight, Pulmonary Assist System in an Ambulatory Sheep Model of Destination Therapy Respiratory Support.

A new, lightweight (2.3 kg), ambulatory pulmonary assist system (PAS) underwent preliminary evaluation in ambulatory sheep. The PAS was purposefully designed for long-term extracorporeal respiratory support for chronic lung disease and utilizes a novel, small (0.9 m 2 surface area) gas exchanger, the pulmonary assist device, with a modified Heart Assist 5 pump fitting in a small wearable pack. Prototype PAS were attached to two sheep in venovenous configuration for 7 and 14 days, evaluating ability to remain thrombus free; maintain gas exchange and blood flow resistance; avoid biocompatibility-related complications while allowing safe ambulation. The PAS achieved 1.56 L/min of flow at 10.8 kRPM with a 24 Fr cannula in sheep one and 2.0 L/min at 10.5 kRPM with a 28 Fr cannula in sheep 2 without significant change. Both sheep walked freely, demonstrating the first application of truly ambulatory ECMO in sheep. While in vitro testing evaluated PAS oxygen transfer rates of 104.6 ml/min at 2 L/min blood flow, oxygen transfer rates averaged 60.6 ml/min and 70.6 ml/min in studies 1 and 2, due to average hemoglobin concentrations lower than humans (8.9 and 10.5 g/dl, respectively). The presented cases support uncomplicated ambulation using the PAS.

Chemotherapy-induced leukopenic septic shock treated with veno-arterial extracorporeal membrane oxygenation: A case report.

We present a case of chemotherapy-induced leukopenic septic shock treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Although the indication for VA-ECMO for septic shock in immunosuppressed states remains controversial, her relatively young age and a slightly increasing leukocyte count led to VA-ECMO induction and resulted in recovery.

Factor XII Silencing Using siRNA Prevents Thrombus Formation in a Rat Model of Extracorporeal Life Support.

Heparin anticoagulation increases the bleeding risk during extracorporeal life support (ECLS). This study determined whether factor XII (FXII) silencing using short interfering RNA (siRNA) can provide ECLS circuit anticoagulation without bleeding. Adult male, Sprague-Dawley rats were randomized to four groups (n = 3 each) based on anticoagulant: (1) no anticoagulant, (2) heparin, (3) FXII siRNA, or (4) nontargeting siRNA. Heparin was administered intravenously before and during ECLS. FXII or nontargeting siRNA were administered intravenously 3 days before the initiation of ECLS via lipidoid nanoparticles. The rats were placed on pumped, arteriovenous ECLS for 8 hours or until the blood flow resistance reached three times its baseline resistance. Without anticoagulant, mock-oxygenator resistance tripled within 7 ± 2 minutes. The resistance in the FXII siRNA group did not increase for 8 hours. There were no significant differences in resistance or mock-oxygenator thrombus volume between the FXII siRNA and the heparin groups. However, the bleeding time in the FXII siRNA group (3.4 ± 0.6 minutes) was significantly shorter than that in the heparin group (5.5 ± 0.5 minutes, p < 0.05). FXII silencing using siRNA provided simpler anticoagulation of ECLS circuits with reduced bleeding time as compared to heparin. http://links.lww.com/ASAIO/A937.

High versus low positive end-expiratory pressure setting in patients receiving veno-venous extracorporeal membrane oxygenation support for severe acute respiratory distress syndrome: study protocol for the multicentre, randomised ExPress SAVER Trial.

INTRODUCTION: While limiting the tidal volume to 6 mL/kg during veno-venous extracorporeal membrane oxygenation (V-V ECMO) to ameliorate lung injury in patients with acute respiratory distress syndrome (ARDS) is widely accepted, the best setting for positive end-expiratory pressure (PEEP) is still controversial. This study is being conducted to investigate whether a higher PEEP setting (15 cmH2O) during V-V ECMO can decrease the duration of ECMO support needed in patients with severe ARDS, as compared with a lower PEEP setting. METHODS AND ANALYSIS: The study is an investigator-initiated, multicentre, open-label, two-arm, randomised controlled trial conducted with the participation of 20 intensive care units (ICUs) at academic as well as non-academic hospitals in Japan. The subjects of the study are patients with severe ARDS who require V-V ECMO support. Eligible patients will be randomised equally to the high PEEP group or low PEEP group. Recruitment to the study will continue until a total of 210 patients with ARDS requiring V-V ECMO support have been randomised. In the high PEEP group, PEEP will be set at 15 cmH2O from the start of V-V ECMO until the trials for liberation from V-V ECMO (or until day 28 after the allocation), while in the low PEEP group, the PEEP will be set at 5 cmH2O. Other treatments will be the same in the two groups. The primary endpoint of the study is the number of ECMO-free days until day 28, defined as the length of time (in days) from successful libration from V-V ECMO to day 28. The secondary endpoints are mortality on day 28, in-hospital mortality on day 60, ventilator-free days during the first 60 days and length of ICU stay. ETHICS AND DISSEMINATION: Ethics approval for the trial at all the participating hospitals was obtained on 27 September 2022, by central ethics approval (IRB at Hiroshima University Hospital, C2022-0006). The results of this study will be presented at domestic and international medical congresses, and also published in scientific journals. TRIAL REGISTRATION NUMBER: The Japan Registry of Clinical Trials jRCT1062220062. Registered on 28 September 2022. PROTOCOL VERSION: 28 March 2023, version 4.0.