Mechanical Ventilation Management during Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome. An International Multicenter Prospective Cohort

Usefulness of implementation of a protective mechanical ventilation bundle during extracorporeal membrane oxygenation for pediatric acute respiratory distress syndrome

BACKGROUND

Defining the best ventilatory settings under extracorporeal membrane oxygenation (ECMO) remains a challenging question. Despite a well-defined acute respiratory distress syndrome (ARDS) treatment before ECMO initiation, there is no recommendation on how to ventilate a patient under ECMO for pediatric acute respiratory distress syndrome (P-ARDS). Only a few descriptive studies are available on ventilatory settings during respiratory ECMO. We aimed to evaluate the usefulness of a protective ventilation bundle under ECMO and its capacity to reduce the ventilatory pressure in our ECMO center.

METHODS

We performed a monocentric retrospective study from January 2007 to December 2018. All children aged from 1 month to 18 years old and requiring an extracorporeal membrane oxygenation for a refractory acute respiratory distress syndrome were included. A protective mechanical ventilation under ECMO bundle has been developed in 2014. We compare the period 1 (before 2014) to the period 2 (after 2014).

RESULTS

Eighty-three patient had been included during the study. We reported a significant increase of positive end-expiratory pressure (PEEP) and mean pressure respectively at day 3, day 7 and day 14 of ECMO during the period 2. Conversely, the driving pressure were significantly lower in the period 2 at day 3 (P=0.009), day 7 (P=0.001) and day 14 (P=0.001). We have also shown a strong increase in the use of prone positioning during ECMO in the period 2 (P=0.01). There was no significant effect of our bundle on the length of mechanical ventilation, of hospitalization and on the survival rate.

CONCLUSIONS

The implementation of a protective mechanical ventilation bundle during ECMO is usefulness to apply for lower ventilatory pressure and higher use of prone positioning. Nonetheless, the lack of power of our study prevents us from showing its efficacy on outcome criteria.

Worldwide application and valuation of extracorporeal membrane oxygenation support during the COVID-19 pandemic (WAVES)

ObjectiveThe outcomes of COVID-19 patients on venovenous extracorporeal membrane oxygenation (VV-ECMO) varied. We aim to investigate the variability concerning location and timeframe. We conducted a retrospective analysis of data from 351 institutions in 53 countries. The primary outcome was survival to hospital discharge or death up to 90 days from ECMO start. The associations between calendar time (month and year) of ECMO initiation and the primary outcome were examined by Cox regression modeling. Multivariable survival analyses were adjusted for the time of ECMO start, age, body mass index, APACHE II, SOFA, and the duration of mechanical ventilation before ECMO.Results1060 adult COVID-19 patients enrolled in the COVID-19 Critical Care Consortium (COVID Critical) international registry and required VV-ECMO support. The study period is from January 2020 to December 2021. The median age was 51 years old, and 70% were male patients. Most patients were from Europe (39.3%) and North America (37.4%). The in-hospital mortality of the entire cohort was 47.12%. In North America and Europe, there was an increased probability of death from May 2020 through February 2021. Latin America showed a steady rate of survival until late in the study. South Asia, the Middle East, and Africa showed an increased chance of mortality around May 2020. In the Asian-Pacific region, after February 2021, there was an increased probability of death. The time of ECMO initiation and advanced patient age were associated with increased mortality.ConclusionVariability in the outcomes of COVID-19 patients on VV-ECMO existed within different regions. This variability reflects the differences in resources, policies, patient selection, management, and possibly COVID-19 virus subtypes. Our findings might help guide global response in the future by early adoption of patient selection protocols, worldwide policies, and delivery of resources.

Prone positioning during veno-venous extracorporeal membrane oxygenation: a systematic review and meta-analysis

PURPOSE

The evidence supporting the benefit on clinical outcomes of prone positioning during veno-venous extracorporeal membrane oxygenation (V-V ECMO) for acute hypoxemic respiratory failure remains inconclusive. We aimed to assess the association of prone positioning, compared to no prone positioning, with 28-day mortality and other clinical outcomes in different patient subgroups.

METHODS

A systematic review and meta-analysis of randomized and non-randomized controlled trials (RCTs) using a random-effects model was conducted. An electronic database search up to September 1st, 2024 was performed (PROSPERO CRD42024517602). The RoB 2 and ROBINS-I tools were used for risk of bias assessments.

RESULTS

We analyzed two RCTs and 20 non-RCTs (3,465 patients). Compared to no prone positioning, the use of prone positioning was associated with lower 28-day (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.42-0.98, p = 0.040, I2 = 66%, low certainty of evidence [CoE]) and hospital mortality (OR 0.67, 95% CI 0.54-0.83, p < 0.001, I2 = 39%, low CoE), despite fewer 28-day ventilator-free days and longer ECMO duration. Younger age (p = 0.005), a higher sequential organ failure assessment (SOFA) score (p = 0.022), non-Covid-19 etiology (p = 0.003), and lower rates of prone positioning before cannulation (p = 0.049) were associated with a greater benefit from prone positioning.

CONCLUSION

In this analysis, among patients supported with V-V ECMO for acute hypoxemic respiratory failure, we observed improved 28-day and hospital mortality in those who received prone positioning, compared to those who did not. However, these findings do not imply causation. Further research is needed to clarify the role of prone positioning in this population.

When to Remove Tracheal Intubation During ECMO Support in Lung Transplant Patients With Idiopathic Pulmonary Fibrosis

BACKGROUND

Lung transplantation is the optimal treatment choice, while extracorporeal membrane oxygenation (ECMO) provides cardiopulmonary support during the perioperative period of lung transplantation. Currently, there is no reported research on the ECMO withdrawal and duration of mechanical ventilation (MV) in idiopathic pulmonary fibrosis (IPF) patients undergoing lung transplantation. Therefore, this study aims to evaluate the impact of ECMO duration on prolonged mechanical ventilation (PMV) time in patients, attempting to explore the relationship between the two.

METHODS

This study included 170 patients with IPF who underwent lung transplantation under ECMO technology. The patients were divided into normal and delayed groups based on the ECMO application time of 72 hours. A multifactor logistic regression analysis was conducted to explore the independent risk factors for PMV time, and restricted cubic spline (RCS) was used to investigate the relationship between ECMO application time and MV time. Receptor operating characteristics (ROC) were further used to find the cut-off value of ECMO application time to predict PMV time.

RESULTS

In the normal group, there were 135 cases, of which 79.25% (107 cases) were males and 20.74% (28 cases) were females, whereas in the delayed group, there were 35 cases, of which 57.14% (20 cases) were males and 42.86% (15 cases) were females. In the RCS curves, there was a nonlinear correlation between the duration of ECMO application and the duration of MV, which tended to increase as the duration of ECMO application increased. According to univariate and multivariate logistic analyses, ECMO application time was an influential factor in the occurrence of PMV time, in which the OR of PMV time was 2.02 (95% CI 1.11,1.63, P = .001) when ECMO application time was ≥ 52.01 hours.

CONCLUSION

After lung transplantation, there is a nonlinear relationship between the application time of ECMO and MV time in patients with IPF. The application time of ECMO can predict well the extension of MV in patients during ICU stay. Therefore, clinicians can assess the duration of MV in patients with IPF based on the application time of ECMO, further avoiding complications related to MV.

Extracorporeal membrane oxygenation for acute lung injury in idiopathic inflammatory myopathies-a potential lifesaving intervention

OBJECTIVES

Idiopathic inflammatory myopathies (IIM) can present with acute IIM-related lung injury and respiratory failure, leading to a high mortality risk in intensive care units (ICU). Extracorporeal membrane oxygenation (ECMO) in acute respiratory distress syndrome can be lifesaving. We aimed to report a case series of IIM patients that received ECMO.

METHODS

Patients with IIM from tertiary care centres in Belgium, Canada, Denmark, USA and Sweden who underwent ECMO were reviewed to describe clinical characteristics, disease outcomes and hospitalization course. Clinical characteristics at admission and during ICU stay including ECMO complications and mortality causes were summarized.

RESULTS

The study included 22 patients (50% female, mean ± SD age at admission 47 ± 12 years) with anti-MDA5 positive dermatomyositis (68%), anti-synthetase syndrome (14%), polymyositis (9%), overlap myositis (5%) and non-MDA5 dermatomyositis (5%). Patients had low comorbidity scores and 46% had received immunosuppression before their ICU admission. Eight (36%) patients died in the ICU, six (27%) were bridged to recovery and eight (36%) were bridged to transplant. When comparing patients bridged to recovery and those who died in the ICU, those who died were older (P = 0.03) and had higher median Charlson comorbidity index scores (P = 0.05). Both groups had similar frequencies of ECMO-related complications (33% vs 50%, P = 0.94).

CONCLUSION

In the patients exposed to ECMO in this case series, 14 were successfully bridged to recovery or transplant, while 8 died in the ICU. Large studies are needed to collect data on clinical outcomes in patients with IIM-ILD exposed to ECMO to identify the best candidates for the intervention.

Can we reduce the risk of neurological injury in critically ill children on initiation of ECLS? A narrative review of potential modifiable factors

Neurological morbidity and mortality remain high in children requiring extracorporeal membrane oxygenation (ECMO). Although the severity of illness at the time of ECMO initiation and the nature of the underlying disease are strongly linked to the development of acute brain injury, several important factors are associated with neurological complications during ECMO support. Many of these factors, particularly those encountered during the early phase of ECMO initiation (first 24 hours), may be modifiable and represent potential targets for interventional studies aiming for improvement of neurological outcomes in pediatric ECMO patients. In this review from the European Extracorporeal Life Support Organization (EuroELSO) Working Group on Neurologic Monitoring and Outcome, we aim to summarize current knowledge on modifiable factors associated with brain injury during ECMO and their potential impact on outcome.

Mechanical Power: Using Ideal Body Weight to Identify Injurious Mechanical Ventilation Thresholds

Identifying the mechanisms of ventilator/ventilation-induced lung injury requires an understanding of the pulmonary physiology involved in the mechanical properties of the lung along with the involvement of the inflammatory cascade. Accurately measuring parameters that represent physiologic lung stress and lung strain at the bedside can be clinically challenging. Although surrogates for lung stress and strain have been proposed, such as plateau pressure and driving pressure, these values only represent a static variable in the ventilator breath. It has been proposed that a single variable could be used as a unifying parameter to identify a threshold for the safe application of mechanical ventilation. The concept of "mechanical power" applies an energy load transfer designation to the ventilator settings and output of tidal volume, airway pressures, and flow. However, there is a potential disconnect between the use of "absolute" mechanical power and the variability of body weight throughout a mixed medical population. Using ideal body weight as an influential factor to express mechanical power can potentially allow for a more accurate depiction of energy applied to the lungs and a potentially reliable injurious mechanical ventilation threshold indicator.

Extracorporeal Membrane Oxygenation Outcomes: COVID-19 Pneumonia vs Non-COVID-19 Pneumonia

BACKGROUND

COVID-19 can cause severe acute respiratory distress syndrome or myocardial dysfunction requiring extracorporeal membrane oxygenation (ECMO). Whether comorbidities or sociodemographic factors influence outcomes in these patients is unclear.

METHODS

Adult patients from the National Inpatient Sample dataset with COVID-19 pneumonia or non-COVID-19 pneumonia who underwent ECMO between 2016 and 2021 were included. Cohorts were matched in a 1:5 ratio using propensity scores. The primary outcome of interest was inpatient mortality; secondary outcomes included length of stay, total hospitalization costs, need for dialysis, rate of vascular complications, and discharge disposition.

RESULTS

Weighted patient groups (COVID-19 pneumonia, 5680 patients; non-COVID-19 pneumonia, 430 patients) were identified. Mean (SD) age was 46.0 (11.2) years in the COVID-19 group, 45.1 (12.5) years in the non-COVID-19 group. After matching, unweighted groups (COVID-19 pneumonia, 1136 patients; non-COVID-19 pneumonia, 86 patients) were compared. Patients with COVID-19 pneumonia had higher mortality risk (odds ratio [OR], 1.98; 95% CI, 1.11-3.53; P = .02), longer stays (38.0 vs 28.5 days, P < .001), higher costs ($1 278 270 vs $967 866, P = .002), and less likelihood of discharge home (OR, 0.42; 95% CI, 0.21-0.85; P = .02) than patients with non-COVID-19 pneumonia. Vascular complication rate (OR, 0.77; 95% CI, 0.27-2.26; P = .64) and need for dialysis (OR, 1.01; 95% CI, 0.49-2.08; P = .97) did not differ between groups.

CONCLUSIONS

Among patients undergoing ECMO, those with COVID-19 pneumonia had worse outcomes than those with non-COVID-19 pneumonia after adjustment for sociodemographic factors and comorbidities.

The Mechanical Power in Patients with Acute Respiratory Distress Syndrome Undergoing Prone Positioning Can Predict Mortality

Background/Objectives: Mechanical power (MP) refers to ventilator-delivered energy to the lungs, which may induce lung injury. We examined the relationship between MP and mortality in patients with acute respiratory distress syndrome (ARDS) who underwent prone positioning. Methods: This multicenter retrospective study included data on all patients admitted to the intensive care units of eight referral hospitals in Taiwan from October 2015 to March 2016, and in Chang Gung Memorial Hospital Linkou branch from January 2017 to October 2023. The data were obtained from the electronic medical records of each hospital by using a standard case report form. MP was calculated as follows: MP (J/min) = 0.098 × VT × RR × (Ppeak - 1/2 × ΔP). Results: We included 135 patients who underwent prone positioning. Among them, 28-day survivors had significantly lower MP (22.6 ± 6.5 vs. 25.3 ± 6.2 J/min, p = 0.024), MP/predicted body weight (PBW) (396.9 ± 118.9 vs. 449.3 ± 118.8 10-3 J/min/kg, p = 0.018), MP/compliance values (0.8 ± 0.3 vs. 1.1 ± 0.4 J/min/mL/cmH2O, p = 0.048) after prone positioning, and significantly lower changes in MP, MP/PBW, and MP/compliance (-0.6 ± 5.7 vs. 2.5 ± 7.4 J/min, p = 0.007; -9.2 ± 97.5 vs. 42.1 ± 127.9 10-3 J/min/kg, p = 0.010; -0.1 ± 0.3 vs. 0.2 ± 0.3 J/min/mL/cmH2O, p < 0.001, respectively). Multivariate Cox regression revealed that the change in MP/compliance (HR: 7.972, p < 0.001) was an independent predictive factor for 28-day mortality. Conclusions: In ARDS patients treated with prone positioning, MP/compliance, and change in MP, MP/PBW, and MP/compliance after prone positioning differed significantly between 28-day survivors and nonsurvivors. Further randomized controlled research is required to elucidate the potential causality of decreased MP and improved clinical outcomes.

Extracorporeal membrane oxygenation for adults with respiratory failure secondary to cardiorespiratory disease: evolving indications and clinical practice

Extracorporeal membrane oxygenation (ECMO) can support patients with severe cardiorespiratory failure presenting with hypoxia who would otherwise have not survived. Patient selection for ECMO is challenging and relies on the integration of physiological variables with an assessment of reversibility of the underlying condition or suitability for transplantation. In this review, we focus on patients with cardiorespiratory disease who may present with severe hypoxia. We will discuss the indications and contraindications for ECMO; the evidence for ECMO, which is limited to a small number of clinical trials and registry data; the complications of ECMO; expanding technologies and indications; the development of a multidisciplinary ECMO network; and future research. The aim is to increase knowledge of this important area for respiratory physicians.

The use of protective mechanical ventilation during extracorporeal membrane oxygenation for the treatment of acute respiratory failure

Acute respiratory failure (ARF) strikes an estimated two million people in the United States each year, with care exceeding US$50 billion. The hallmark of ARF is a heterogeneous injury, with normal tissue intermingled with a large volume of low compliance and collapsed tissue. Mechanical ventilation is necessary to oxygenate and ventilate patients with ARF, but if set inappropriately, it can cause an unintended ventilator-induced lung injury (VILI). The mechanism of VILI is believed to be overdistension of the remaining normal tissue known as the 'baby' lung, causing volutrauma, repetitive collapse and reopening of lung tissue with each breath, causing atelectrauma, and inflammation secondary to this mechanical damage, causing biotrauma. To avoid VILI, extracorporeal membrane oxygenation (ECMO) can temporally replace the pulmonary function of gas exchange without requiring high tidal volumes (VT) or airway pressures. In theory, the lower VT and airway pressure will minimize all three VILI mechanisms, allowing the lung to 'rest' and heal in the collapsed state. The optimal method of mechanical ventilation for the patient on ECMO is unknown. The ARDSNetwork Acute Respiratory Management Approach (ARMA) is a Rest Lung Approach (RLA) that attempts to reduce the excessive stress and strain on the remaining normal lung tissue and buys time for the lung to heal in the collapsed state. Theoretically, excessive tissue stress and strain can also be avoided if the lung is fully open, as long as the alveolar re-collapse is prevented during expiration, an approach known as the Open Lung Approach (OLA). A third lung-protective strategy is the Stabilize Lung Approach (SLA), in which the lung is initially stabilized and gradually reopened over time. This review will analyze the physiologic efficacy and pathophysiologic potential of the above lung-protective approaches.

Extracorporeal Support for Acute Respiratory Distress Syndrome

Extracorporeal life support (ECLS) has a long history in the management of the acute respiratory distress syndrome (ARDS). The objectives of this review are to summarize the rationale and evidence for ECLS in ARDS including its role in reducing ventilator-induced lung injury (VILI), suggest best practice management strategies during ECLS, and identify areas that require additional research to better inform patient care.

Mechanical Power Is Associated With Mortality in Pressure-Controlled Ventilated Patients: A Dutch, Single-Center Cohort Study

IMPORTANCE

Mechanical power (MP) could serve as a valuable parameter in clinical practice to estimate the likelihood of adverse outcomes. However, the safety thresholds for MP in mechanical ventilation remain underexplored and contentious.

OBJECTIVES

This study aims to investigate the association between MP and hospital mortality across varying degrees of lung disease severity, classified by Pao2/Fio2 ratios.

DESIGN, SETTING, AND PARTICIPANTS

This is a retrospective cohort study using automatically extracted data. Patients admitted to the ICU of a tertiary referral hospital in The Netherlands between 2018 and 2024 and ventilated in pressure-controlled mode were included.

MAIN OUTCOMES AND MEASURES

Logistic regression, adjusted for age, sex, Acute Physiology and Chronic Health Evaluation-IV score, and Pao2/Fio2 ratio, was used to calculate the odds ratio (OR) for all-cause in-hospital mortality.

RESULTS

A total of 2184 patients were analyzed, with a mean age of 62.5 ± 13.8 years, of whom 1508 (70.2%) were male. The mean MP was highest in patients with the lowest Pao2/Fio2 ratios (21.5 ± 6.5 J/min) compared with those with the highest ratios (12.0 ± 3.8 J/min; p < 0.001). Adjusted analyses revealed that increased MP was associated with higher mortality (OR, 1.06; 95% CI, 1.03-1.09 per J/min increase). Similarly, MP normalized for body weight showed a stronger association with mortality (OR, 1.004; 95% CI, 1.002-1.006 per J/min/kg increase). An increase in mortality was seen when MP exceeded 16-18 J/min.

CONCLUSIONS AND RELEVANCE

Our findings demonstrate a significant association between MP and hospital mortality, even after adjusting for key confounders. Mortality increases notably when MP exceeds 16-18 J/min. Normalized MP presents an even stronger association with mortality. These results underscore the need for further research into ventilation strategies that consider MP adjustments.

Carbon Dioxide Targets in Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome

Target values for arterial carbon dioxide tension (PaCO 2 ) in extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) are unknown. We hypothesized that lower PaCO 2 values on ECMO would be associated with lighter sedation. We used data from two independent patient cohorts with ARDS spending 1,177 days (discovery cohort, 69 patients) and 516 days (validation cohort, 70 patients) on ECMO and evaluated the associations between daily PaCO 2 , pH, and bicarbonate (HCO 3 ) with sedation. Median PaCO 2 was 41 (interquartile range [IQR] = 37-46) mm Hg and 41 (IQR = 37-45) mm Hg in the discovery and the validation cohort, respectively. Lower PaCO 2 and higher pH but not bicarbonate (HCO 3 ) served as significant predictors for reaching a Richmond Agitation Sedation Scale (RASS) target range of -2 to +1 (lightly sedated to restless). After multivariable adjustment for mortality, tracheostomy, prone positioning, vasoactive inotropic score, Simplified Acute Physiology Score (SAPS) II or Sequential Organ Failure Assessment (SOFA) Score and day on ECMO, only PaCO 2 remained significantly associated with the RASS target range (adjusted odds ratio 1.1 [95% confidence interval (CI) = 1.01-1.21], p = 0.032 and 1.29 [95% CI = 1.1-1.51], p = 0.001 per mm Hg decrease in PaCO 2 for the discovery and the validation cohort, respectively). A PaCO 2 ≤40 mm Hg, as determined by the concordance probability method, was associated with a significantly increased probability of a sedation level within the RASS target range in both patient cohorts (adjusted odds ratio = 2.92 [95% CI = 1.17-7.24], p = 0.021 and 6.82 [95% CI = 1.50-31.0], p = 0.013 for the discovery and the validation cohort, respectively).

Prone position ventilation-induced oxygenation improvement as a valuable predictor of survival in patients with acute respiratory distress syndrome: a retrospective observational study

BACKGROUND

In patients with severe acute respiratory distress syndrome (ARDS), prolonged and inappropriate use of prone position ventilation (PPV) is a known risk factor for mortality. Hence, it is critical to monitor patients' response to PPV and accurately differentiate responders from non-responders at an early stage. The study aimed to investigate the relationship between oxygenation improvement after three rounds of PPV and survival rate in patients with pulmonary ARDS. Additionally, we sought to identify the earliest turning point for escalation from PPV to extracorporeal membrane oxygenation.

METHODS

We performed a retrospective observational study from 2015 to 2023. We included adult patients who received invasive mechanical ventilation, underwent at least three periods of at least 6 h of PPV after admission to the Intensive Care Unit, and meet the ARDS criteria. The study collected data on each PPV session, including changes in PaCO2, PaO2, pH, FiO2, PaO2:FiO2 ratio, and clinical outcomes.

RESULTS

A total of 104 patients were enrolled in the study. The change in PaCO2 from baseline to the third PPV session (P3) had the highest area under the receiver operating characteristic curve (AUC) of 0.70 (95% CI 0.60-0.80; p < 0.001) for predicting hospital mortality, with an optimal cut-off point of 3.15 (sensitivity 75.9%, specificity 56.0%). The percentage change in PaO2:FiO2 ratio from baseline to P3 also had significant AUC of 0.71 (95% CI 0.61-0.81; p < 0.001) for predicting hospital mortality, with an optimal cut-off value of 99.465 (sensitivity 79.6%, specificity 62.0%). PaCO2 responders were defined as those with an increase in PaCO2 of ≤ 3.15% from baseline to P3, while PaO2:FiO2 responders were defined as those with an increase in PaO2:FiO2 ratio of ≥ 99.465% from baseline to P3. In the multivariable Cox analysis, PaO2:FiO2 responders had a significantly lower 60-day mortality risk (hazard ratio 0.369; 95% CI 0.171-0.798; p = 0.011).

CONCLUSIONS

The percentage change in PaO2:FiO2 ratio from baseline to P3 was a significant predictor of outcomes. The model fit and prediction accuracy were improved by including the variable of PaCO2 responders.

Use of prone position ventilation in patients with COVID-19 induced severe ARDS supported with V-V ECMO: A danish cohort study with focus on adverse events

INTRODUCTION

Prone position ventilation (PPV) of patients with adult respiratory distress syndrome (ARDS) supported with veno-venous extracorporeal membrane oxygenation (V-V ECMO) may improve oxygenation and alveolar recruitment and is recommended when extensive dorsal consolidations are present, but only few data regarding adverse events (AE) related to PPV in this group of patients have been published.

METHODS

Nationwide retrospective analysis of 68 COVID-19 patients admitted from March 2020 - December 2021 with severe ARDS and need of V-V ECMO support. The number of patients treated with PPV, number of PPV-events, timing, the time spent in prone position, number and causes of AE are reported. Causes to stop the PPV regimen and risk factors for AE were explored.

RESULTS

44 out of 68 patients were treated with PPV, and 220 PPV events are evaluated. AE were identified in 99 out of 220 (45%) PPV events and occurred among 31 patients (71%). 1 fatal PPV related AE was registered. Acute supination occurred in 19 events (9%). Causes to stop the PPV regimen were almost equally distributed between effect (weaned from ECMO), no effect, death (of other reasons) and AE. Frequent causes of AE were pressures sores and ulcers, hypoxia, airway related and ECMO circuit related. Most AE occurred during patients first or second PPV event.

CONCLUSIONS

PPV treatment was found to carry a high incidence of PPV related AE in these patients. Causes and preventive measures to reduce occurrence of PPV related AE during V-V ECMO support need further exploration.

Identification of novel sub-phenotypes of severe ARDS requiring ECMO using latent class analysis

BACKGROUND

Sub-phenotyping of acute respiratory distress syndrome (ARDS) could be useful for evaluating the severity of ARDS or predicting its responsiveness to given therapeutic strategies, but no studies have yet investigated the heterogeneity of patients with severe ARDS requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO).

METHODS

We conducted this retrospective multicenter observational study in adult patients with severe ARDS treated by V-V ECMO. We performed latent class analysis (LCA) for identifying sub-phenotypes of severe ARDS based on the radiological and clinical findings at the start of ECMO support. Multivariate Cox regression analysis was conducted to investigate the differences in mortality and association between the PEEP setting of ≥ 10 cmH2O and mortality by the sub-phenotypes.

RESULTS

We identified three sub-phenotypes from analysis of the data of a total of 544 patients with severe ARDS treated by V-V ECMO, as follows: Dry type (n = 185; 34%); Wet type (n = 169; 31%); and Fibrotic type (n = 190; 35%). The 90-days in-hospital mortality risk was higher in the patients with the Fibrotic type than in those with the Dry type (adjusted hazard ratio [95% confidence interval] 1.75 [1.10-2.79], p = 0.019) or the Wet type (1.50 [1.02-2.23], p = 0.042). The PEEP setting of ≥ 10 cmH2O during the first 3 days of ECMO decreased the 90-days in-hospital mortality risk only in patients with the Wet type, and not in those with the Dry or Fibrotic type. A significant interaction effect was observed between the Wet type and the PEEP setting of ≥ 10 cmH2O in relation to the 90-day in-hospital mortality (pinteraction = 0.036).

CONCLUSIONS

The three sub-phenotypes showed different mortality rates and different relationships between higher PEEP settings in the early phase of V-V ECMO and patient outcomes. Our data suggest that we may need to change our management approach to patients with severe ARDS during V-V ECMO according to their clinical sub-phenotype.

The use of prone position ventilation in Danish patients with COVID-19-induced severe acute respiratory distress syndrome treated with veno-venous extracorporeal membrane oxygenation: A nationwide cohort study with focus on pulmonary effects

BACKGROUND

Prone position ventilation (PPV) is recommended for patients with COVID-19 induced severe Adult Respiratory Distress Syndrome (ARDS) and is used for patients supported with V-V ECMO as well. The purpose of this study was to describe the use of PPV in these patients focusing on physiological effects with the hypothesis that PPV could reduce oxygen need and improve dynamic compliance.

METHODS

This study was a nationwide retrospective analysis of all COVID-19 patients in Denmark from March 2020 - December 2021 with severe ARDS and need of V-V ECMO support. Data on the number of patients treated with PPV, number of PPV sessions, timing, the time spent in prone position, pulmonary physiological response types with analysis of variables affecting the response are reported.

RESULTS

Out of 68 patients 44 were treated with 220 PPV sessions and a positive clinical response was observed in 80% of patients but only in 45% of sessions. On a single session level, increased compliance was observed in 38% and increased oxygenation in only 15% of 220 sessions, with within-patient heterogeneity. Higher dynamic compliance at the beginning of a PPV session was associated with a lower delta change in dynamic compliance during PPV. The response to a PPV session could not be predicted by the response in the prior session. Dynamic compliance did not change during the ECMO course.

CONCLUSION

Eighty percent of patients responded positively during a PPV session, but this was not associated with overall pulmonary improvement. On a single patient level, responses were heterogenous and only 45% of sessions resulted in clinical improvement. Response in dynamic compliance was associated with starting values of compliance.

Mapping a Decade (2014-2024) of Research on Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: A Visual Analysis with CiteSpace and VOSviewer

Background

Acute Respiratory Distress Syndrome (ARDS) stands as a primary cause of mortality among critically ill patients. Extracorporeal Membrane Oxygenation (ECMO) is increasingly employed in the rescue therapy of ARDS patients. However, the current status of research in the field of ECMO-assisted ARDS remains unclear.

Objective

This research aims to categorize and evaluate the literature regarding Extracorporeal Membrane Oxygenation (ECMO) support for Acute Respiratory Distress Syndrome (ARDS), offering a comprehensive analysis of bibliometric properties, research hotspots, and developmental trends within the domain of ECMO-assisted ARDS.

Methods

A literature search was conducted for ECMO-assisted support for patients with ARDS in the Web of Science Core Collection (WoSCC) database from 2014 to 2024. We employed visualization tools such as CiteSpace and VOSviewer to explore and assess connections among nations, institutions, researchers, and co-cited journals, authors, references, and keywords.

Results

This study included 1739 publications. The United States leads in publication volume with Columbia University at the forefront of ECMO research. Intensive Care Medicine has been identified as the most cited journal in this field. Alain Combes from France stands out as a key contributor, particularly in his 2018 publication in the New England Journal of Medicine, which is the most cited work in the discipline. Furthermore, keyword analysis identified three distinct research phases: examining complications associated with ECMO therapy, exploring optimal strategies for mechanical ventilation under ECMO support, and compiling insights into the application of ECMO in treating COVID-19 patients and in the development of predictive models for patient outcomes.

Conclusion

Using bibliometric visualization techniques, this study revealed significant progress in the use of ECMO for treating ARDS respiratory support, evaluated the impact of these findings, and outlined potential areas for future studies.

Mechanical ventilation settings during weaning from venovenous extracorporeal membrane oxygenation

BACKGROUND

The optimal timing of weaning from venovenous extracorporeal membrane oxygenation (VV ECMO) and its modalities have been rarely studied.

METHODS

Retrospective, multicenter cohort study over 7 years in two tertiary ICUs, high-volume ECMO centers in France and Italy. Patients with ARDS on ECMO and successfully weaned from VV ECMO were classified based on their mechanical ventilation modality during the sweep gas-off trial (SGOT) with either controlled mechanical ventilation or spontaneous breathing (i.e. pressure support ventilation). The primary endpoint was the time to successful weaning from mechanical ventilation within 90 days post-ECMO weaning.

RESULTS

292 adult patients with severe ARDS were weaned from controlled ventilation, and 101 were on spontaneous breathing during SGOT. The 90-day probability of successful weaning from mechanical ventilation was not significantly different between the two groups (sHR [95% CI], 1.23 [0.84-1.82]). ECMO-related complications were not statistically different between patients receiving these two mechanical ventilation strategies. After adjusting for covariates, older age, higher pre-ECMO sequential organ failure assessment score, pneumothorax, ventilator-associated pneumonia, and renal replacement therapy, but not mechanical ventilation modalities during SGOT, were independently associated with a lower probability of successful weaning from mechanical ventilation after ECMO weaning.

CONCLUSIONS

Time to successful weaning from mechanical ventilation within 90 days post-ECMO was not associated with the mechanical ventilation strategy used during SGOT. Further research is needed to assess the optimal ventilation strategy during weaning off VV ECMO and its impact on short- and long-term outcomes.

Low-Frequency Ventilation May Facilitate Weaning in Acute Respiratory Distress Syndrome Treated with Extracorporeal Membrane Oxygenation: A Randomized Controlled Trial

Although extracorporeal membrane ventilation offers the possibility for low-frequency ventilation, protocols commonly used in patients with acute respiratory distress syndrome (ARDS) and treated with extracorporeal membrane oxygenation (ECMO) vary largely. Whether strict adherence to low-frequency ventilation offers benefit on important outcome measures is poorly understood. Background/Objectives: This pilot clinical study investigated the efficacy of low-frequency ventilation on ventilator-free days (VFDs) in patients suffering from ARDS who were treated with ECMO therapy. Methods: In this single-center randomized controlled trial, 44 (70% male) successive ARDS patients treated with ECMO (aged 56 ± 12 years, SAPS III 64 (SD ± 14)) were randomly assigned 1:1 to the control group (conventional ventilation) or the treatment group (low-frequency ventilation during first 72 h on ECMO: respiratory rate 4-5/min; PEEP 14-16 cm H2O; plateau pressure 23-25 cm H2O, tidal volume: <4 mL/kg). The primary endpoint was VFDs at day 28 after starting ECMO treatment. The major secondary endpoint was ICU mortality, 28-day mortality and 90-day mortality. Results: Twenty-three (52%) patients were successfully weaned from ECMO and were discharged from the intensive care unit (ICU). Twelve patients in the treatment group and five patients in the control group showed more than one VFD at day 28 of ECMO treatment. VFDs were 3.0 (SD ± 5.5) days in the control group and 5.4 (SD ± 6) days in the treatment group (p = 0.117). Until day 28 of ECMO initiation, patients in the treatment group could be successfully weaned off of the ventilator more often (OR of 0.164 of 0 VFDs at day 28 after ECMO start; 95% CI 0.036-0.758; p = 0.021). ICU mortality did not differ significantly (36% in treatment group and 59% in control group; p = 0.227). Conclusions: Low-frequency ventilation is comparable to conventional protective ventilation in patients with ARDS who have been treated with ECMO. However, low-frequency ventilation may support weaning from invasive mechanical ventilation in patients suffering from ARDS and treated with ECMO therapy.

Positive end-expiratory pressure management in patients with severe ARDS: implications of prone positioning and extracorporeal membrane oxygenation

The optimal strategy for positive end-expiratory pressure (PEEP) titration in the management of severe acute respiratory distress syndrome (ARDS) patients remains unclear. Current guidelines emphasize the importance of a careful risk-benefit assessment for PEEP titration in terms of cardiopulmonary function in these patients. Over the last few decades, the primary goal of PEEP usage has shifted from merely improving oxygenation to emphasizing lung protection, with a growing focus on the individual pattern of lung injury, lung and chest wall mechanics, and the hemodynamic consequences of PEEP. In moderate-to-severe ARDS patients, prone positioning (PP) is recommended as part of a lung protective ventilation strategy to reduce mortality. However, the physiologic changes in respiratory mechanics and hemodynamics during PP may require careful re-assessment of the ventilation strategy, including PEEP. For the most severe ARDS patients with refractory gas exchange impairment, where lung protective ventilation is not possible, veno-venous extracorporeal membrane oxygenation (V-V ECMO) facilitates gas exchange and allows for a "lung rest" strategy using "ultraprotective" ventilation. Consequently, the importance of lung recruitment to improve oxygenation and homogenize ventilation with adequate PEEP may differ in severe ARDS patients treated with V-V ECMO compared to those managed conservatively. This review discusses PEEP management in severe ARDS patients and the implications of management with PP or V-V ECMO with respect to respiratory mechanics and hemodynamic function.

Early reapplication of prone position during venovenous ECMO for acute respiratory distress syndrome: a prospective observational study and propensity-matched analysis

BACKGROUND

A combination of prone positioning (PP) and venovenous extracorporeal membrane oxygenation (VV-ECMO) is safe, feasible, and associated with potentially improved survival for severe acute respiratory distress syndrome (ARDS). However, whether ARDS patients, especially non-COVID-19 patients, placed in PP before VV-ECMO should continue PP after a VV-ECMO connection is unknown. This study aimed to test the hypothesis that early use of PP during VV-ECMO could increase the proportion of patients successfully weaned from ECMO support in severe ARDS patients who received PP before ECMO.

METHODS

In this prospective observational study, patients with severe ARDS who were treated with VV-ECMO were divided into two groups: the prone group and the supine group, based on whether early PP was combined with VV-ECMO. The proportion of patients successfully weaned from VV-ECMO and 60-day mortality were analyzed before and after propensity score matching.

RESULTS

A total of 165 patients were enrolled, 50 in the prone and 115 in the supine group. Thirty-two (64%) and 61 (53%) patients were successfully weaned from ECMO in the prone and the supine groups, respectively. The proportion of patients successfully weaned from VV-ECMO in the prone group tended to be higher, albeit not statistically significant. During PP, there was a significant increase in partial pressure of arterial oxygen (PaO2) without a change in ventilator or ECMO settings. Tidal impedance shifted significantly to the dorsal region, and lung ultrasound scores significantly decreased in the anterior and posterior regions. Forty-five propensity score-matched patients were included in each group. In this matched sample, the prone group had a higher proportion of patients successfully weaned from VV-ECMO (64.4% vs. 42.2%; P = 0.035) and lower 60-day mortality (37.8% vs. 60.0%; P = 0.035).

CONCLUSIONS

Patients with severe ARDS placed in PP before VV-ECMO should continue PP after VV-ECMO support. This approach could increase the probability of successful weaning from VV-ECMO.

TRIAL REGISTRATION

ClinicalTrials.Gov: NCT04139733. Registered 23 October 2019.

Respiratory extracorporeal membrane oxygenation : From rescue therapy to standard tool for treatment of acute respiratory distress syndrome?

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) for patients with acute respiratory distress syndrome (ARDS) has increased substantially. With modern trials supporting its efficacy, ECMO has become an important tool in the management of severe ARDS.

OBJECTIVES

The objectives of this paper are to discuss ECMO physiology and configurations used for patients with ARDS, review evidence supporting the use of ECMO for ARDS, and discuss aspects of management during ECMO.

CONCLUSION

Current evidence supports the use of ECMO, combined with an ultra-lung-protective approach to mechanical ventilation, in patients with ARDS who have refractory hypoxemia or hypercapnia with severe respiratory acidosis. Furthermore, data suggest that center volume and experience are important factors in the care of patients receiving ECMO. The use of extracorporeal technologies in expanded patient populations and the optimal management of patients during ECMO remain areas of investigation. This article is freely available.

Identifying novel clinical phenotypes of acute respiratory distress syndrome using trajectories of daily fluid balance: a secondary analysis of randomized controlled trials

BACKGROUND

Previously identified phenotypes of acute respiratory distress syndrome (ARDS) could not reveal the dynamic change of phenotypes over time. We aimed to identify novel clinical phenotypes in ARDS using trajectories of fluid balance, to test whether phenotypes respond differently to different treatment, and to develop a simplified model for phenotype identification.

METHODS

FACTT (conservative vs liberal fluid management) trial was classified as a development cohort, joint latent class mixed models (JLCMMs) were employed to identify trajectories of fluid balance. Heterogeneity of treatment effect (HTE) for fluid management strategy across phenotypes was investigated. We also constructed a parsimonious probabilistic model using baseline data to predict the fluid trajectories in the development cohort. The trajectory groups and the probabilistic model were externally validated in EDEN (initial trophic vs full enteral feeding) trial.

RESULTS

Using JLCMM, we identified two trajectory groups in the development cohort: Class 1 (n = 758, 76.4% of the cohort) had an early positive fluid balance, but achieved negative fluid balance rapidly, and Class 2 (n = 234, 24.6% of the cohort) was characterized by persistent positive fluid balance. Compared to Class 1 patients, patients in Class 2 had significantly higher 60-day mortality (53.5% vs. 17.8%, p < 0.001), and fewer ventilator-free days (0 vs. 20, p < 0.001). A significant HTE between phenotypes and fluid management strategies was observed in the FACTT. An 8-variables model was derived for phenotype assignment.

CONCLUSIONS

We identified and validated two novel clinical trajectories for ARDS patients, with both prognostic and predictive enrichment. The trajectories of ARDS can be identified with simple classifier models.

[Ventilation concepts under extracorporeal membrane oxygenation (ECMO) in acute respiratory distress syndrome (ARDS)]

Extracorporeal membrane oxygenation (ECMO) is often the last resort for escalation of treatment in patients with severe acute respiratory distress syndrome (ARDS). The success of treatment is mainly determined by patient-specific factors, such as age, comorbidities, duration and invasiveness of the pre-existing ventilation treatment as well as the expertise of the treating ECMO center. In particular, the adjustment of mechanical ventilation during ongoing ECMO treatment remains controversial. Although a reduction of invasiveness of mechanical ventilation seems to be reasonable due to physiological considerations, no improvement in outcome has been demonstrated so far for the use of ultraprotective ventilation regimens.

Advanced Respiratory Monitoring during Extracorporeal Membrane Oxygenation

Advanced respiratory monitoring encompasses a diverse range of mini- or noninvasive tools used to evaluate various aspects of respiratory function in patients experiencing acute respiratory failure, including those requiring extracorporeal membrane oxygenation (ECMO) support. Among these techniques, key modalities include esophageal pressure measurement (including derived pressures), lung and respiratory muscle ultrasounds, electrical impedance tomography, the monitoring of diaphragm electrical activity, and assessment of flow index. These tools play a critical role in assessing essential parameters such as lung recruitment and overdistention, lung aeration and morphology, ventilation/perfusion distribution, inspiratory effort, respiratory drive, respiratory muscle contraction, and patient-ventilator synchrony. In contrast to conventional methods, advanced respiratory monitoring offers a deeper understanding of pathological changes in lung aeration caused by underlying diseases. Moreover, it allows for meticulous tracking of responses to therapeutic interventions, aiding in the development of personalized respiratory support strategies aimed at preserving lung function and respiratory muscle integrity. The integration of advanced respiratory monitoring represents a significant advancement in the clinical management of acute respiratory failure. It serves as a cornerstone in scenarios where treatment strategies rely on tailored approaches, empowering clinicians to make informed decisions about intervention selection and adjustment. By enabling real-time assessment and modification of respiratory support, advanced monitoring not only optimizes care for patients with acute respiratory distress syndrome but also contributes to improved outcomes and enhanced patient safety.

Secondary pneumomediastinum in COVID-19 patient: A case managed with VV-ECMO

Air leak syndrome, including pneumomediastinum (PM), pneumopericardium, pneumothorax, or subcutaneous emphysema, is primarily caused by chest trauma, cardiothoracic surgery, esophageal perforation, and mechanical ventilation. Secondary pneumomediastinum (SP) is a rare complication, with a much lower incidence reported in patients with coronavirus disease 2019 (COVID-19). Our patient was a 44-year-old nonsmoker male with a previous history of obesity (Body Mass Index [BMI] 35 kg/m2), hyperthyroidism, hypokinetic cardiopathy and atrial fibrillation in treatment with flecainide, who presented to the emergency department with 6 days of fever, cough, dyspnea, and respiratory distress. The COVID-19 diagnosis was confirmed based on a polymerase chain reaction (PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). After initiation of mechanical ventilation, a chest computed tomography (CT) on the first day revealed bilateral multifocal ground-glass opacities, consolidation and an extensive SP and pneumoperitoneum. Our therapeutic strategy was initiation of veno-venous extracorporeal membrane oxygenation (VV-ECMO) as a bridge to recovery after positioning 2 drains (mediastinal and pleural), for both oxygenation and carbon dioxide clearance, to allow protective and ultra-protective ventilation to limit ventilator-induced lung injury (VILI) and the intensity of mechanical power for lung recovery. After another chest CT scan which showed a clear reduction of the PM, 2 pronation and neuromuscular relaxation cycles were also required, with improvement of gas exchange and respiratory mechanics. On the 15th day, lung function recovered and the patient was then weaned from VV-ECMO, and ultimately made a good recovery and was discharged. In conclusion, SP may be a reflection of extensive alveolar damage and should be considered as a potential predictive factor for adverse outcome in critically ill SARS-CoV2 patients.

Factors associated with decreased compliance after on-site extracorporeal membrane oxygenation cannulation for acute respiratory distress syndrome: A retrospective, observational cohort study

Background

Extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) is systematically associated with decreased respiratory system compliance (CRS). It remains unclear whether transportation to the referral ECMO center, changes in ventilatory mode or settings to achieve ultra-protective ventilation, or the natural evolution of ARDS drives this change in respiratory mechanics. Herein, we assessed the precise moment when CRS decreases after ECMO cannulation and identified factors associated with decreased CRS.

Methods

To rule out the effect of transportation and the different modes of ventilation on CRS, we conducted a retrospective, single-center, observational cohort study from January 2013 to May 2020, on 22 patients with severe ARDS requiring on-site ECMO and ventilated in pressure-controlled mode to achieve ultra-protective ventilation. CRS was assessed at different time points ranging from 12 h before ECMO cannulation to 72 h after ECMO cannulation. The primary outcome was the relative change in CRS between 3 h before and 3 h after ECMO cannulation. The secondary outcomes included variables associated with the relative changes in CRS within the first 3 h after ECMO cannulation and the relative changes in CRS at each time point.

Results

CRS decreased within the first 3 h after ECMO cannulation (-28.3%, 95% confidence interval [CI]: -38.8 to -17.9, P<0.001), while the decrease was mild before and after these first 3 h after ECMO cannulation. To achieve ultra-protective ventilation, respiratory rate decreased in the mean by -13 breaths/min (95% CI: -15 to -11) and driving pressure by -8.3 cmH2O (95% CI: -11.2 to -5.3), resulting in decreased tidal volume by -3.3 mL/kg of predicted body weight (95% CI: -3.9 to -2.6) as compared to before ECMO cannulation (P <0.001 for all). Plateau pressure reduction, driving pressure reduction, and tidal volume reduction were significantly associated with decreased CRS after ECMO cannulation, whereas neither respiratory rate, positive end-expiratory pressure, inspired fraction of oxygen, fluid balance, nor mean airway pressure was associated with decreased CRS.

Conclusions

Decreased driving pressure resulting in lower tidal volume to achieve ultra-protective ventilation after ECMO cannulation was associated with a marked decrease in CRS in ARDS patients with on-site ECMO cannulation.

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

BACKGROUND

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.

METHODS

Recent guidelines, randomized trials, and registry data underscore the importance of lung-protective ventilation during respiratory and cardiac support on ECMO.

RESULTS

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 >10 mm 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.

CONCLUSION

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.

Anti-Xa Assay Monitoring Improves the Precision of Anticoagulation in Venovenous Extracorporeal Membrane Oxygenation

Unfractionated heparin (UFH) is the most used anticoagulant in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO). Its therapeutic levels are monitored using activated partial thromboplastin time ratio (aPTTr) or antifactor Xa (anti-Xa) assay. This was a retrospective, single-center, cohort study where all adult patients with viral etiology respiratory failure requiring VV-ECMO from January 2, 2015 to January 31, 2022 were included. Anticoagulation was monitored using aPTTr (until November 1, 2019) or anti-Xa assay (after November 1, 2019). We compared the accuracy and precision of anticoagulation monitoring tests using time in therapeutic range (TTR) and variance growth rate (VGR), respectively, and their impact on bleeding and thrombotic events (BTEs). A total of 254 patients, 74 in aPTTr and 180 in anti-Xa monitoring groups, were included with a total of 4,992 ECMO-person days. Accuracy was comparable: mean TTR of 47% in aPTTr and 51% in anti-Xa groups ( p = 0.28). Antifactor Xa monitoring group demonstrated improved precision with a lower variance (median VGR 0.21 vs. 1.61 in aPTTr, p < 0.05). Secondary outcome of less heparin prescription changes (adjusted rate ratio [RR] = 1.01, p = 0.01), fewer blood transfusions (adjusted RR = 0.78, p < 0.05), and ECMO circuit changes (adjusted RR = 0.68, p < 0.05) were seen with anti-Xa monitoring.

International Survey on Mechanical Ventilation During Extracorporeal Membrane Oxygenation

The optimal ventilation strategy for patients on extracorporeal membrane oxygenation (ECMO) remains uncertain. This survey reports current mechanical ventilation strategies adopted by ECMO centers worldwide. An international, multicenter, cross-sectional survey was conducted anonymously through an internet-based tool. Participants from North America, Europe, Asia, and Oceania were recruited from the extracorporeal life support organization (ELSO) directory. Responses were received from 48 adult ECMO centers (response rate 10.6%). Half of these had dedicated ventilation protocols for ECMO support. Pressure-controlled ventilation was the preferred initial ventilation mode for both venovenous ECMO (VV-ECMO) (60%) and venoarterial ECMO (VA-ECMO) (34%). In VV-ECMO, the primary goal was lung rest (93%), with rescue therapies commonly employed, especially neuromuscular blockade (93%) and prone positioning (74%). Spontaneous ventilation was typically introduced after signs of pulmonary recovery, with few centers using it as the initial mode (7%). A quarter of centers stopped sedation within 3 days after ECMO initiation. Ventilation strategies during VA-ECMO focused less on lung-protective goals and transitioned to spontaneous ventilation earlier. Ventilation strategies during ECMO support differ considerably. Controlled ventilation is predominantly used initially to provide lung rest, often facilitated by sedation and neuromuscular blockade. Few centers apply "awake ECMO" early during ECMO support, some utilizing partial neuromuscular blockade.

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.

Right ventricular injury in patients with COVID-19-related ARDS eligible for ECMO support: a multicenter retrospective study

BACKGROUND

Coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS) is associated with high mortality. Extracorporeal membrane oxygenation (ECMO) has been proposed in this setting, but optimal criteria to select target patients remain unknown. Our hypothesis is that evaluation of right ventricular (RV) function could be helpful. The aims of our study were to report the incidence and outcomes of patients eligible for ECMO according to EOLIA criteria, and to identify a subgroup of patients with RV injury, which could be a target for ECMO.

METHODS

Retrospective observational study involving 3 French intensive care units (ICUs) of teaching hospitals. Patients with confirmed SARS-CoV-2 infection between March 2020 and March 2021, presenting ARDS and with available echocardiography, were included. Patients were classified in three groups according to whether or not they met the EOLIA criteria and the presence of RV injury (RVI) ("EOLIA -", "EOLIA + RVI -" and "EOLIA + RVI + "). RVI was defined by the association of RV to left ventricular end-diastolic area ratio > 0.8 and paradoxical septal motion. Kaplan-Meier survival curves were used to analyze outcome as well as a Cox model for 90 day mortality.

RESULTS

915 patients were hospitalized for COVID-19, 418 of them with ARDS. A total of 283 patients with available echocardiography were included. Eighteen (6.3%) patients received ECMO. After exclusion of these patients, 107 (40.5%) were classified as EOLIA -, 126 (47.5%) as EOLIA + RVI -, and 32 (12%) as EOLIA + RVI + . Ninety-day mortality was 21% in the EOLIA-group, 44% in the EOLIA + RVI-group, and 66% in the EOLIA + RVI + group (p < 0.001). After adjustment, RVI was statistically associated with 90-day mortality (HR = 1.92 [1.10-3.37]).

CONCLUSIONS

Among COVID-19-associated ARDS patients who met the EOLIA criteria, those with significant RV pressure overload had a particularly poor outcome. This subgroup may be a more specific target for ECMO. This represented 12% of our cohort compared to 60% of patients who met the EOLIA criteria only. How the identification of this high-risk subset of patients translates into patient-centered outcomes remains to be evaluated.

Lung Ultrasound Evaluation of Aeration Changes in Response to Prone Positioning in Acute Respiratory Distress Syndrome (ARDS) Patients Requiring Venovenous Extracorporeal Membrane Oxygenation: An Observational Study

BACKGROUND

Prone positioning (PP) has been proven to be a beneficial approach in enhancing survival outcomes for patients with severe acute respiratory distress syndrome (ARDS) who need venovenous extracorporeal membrane oxygenation (V-V ECMO) support. The study utilized bedside lung ultrasound (LUS) to evaluate changes in lung aeration caused by PP in ARDS patients receiving V-V ECMO.

METHODS

This retrospective single-center study involved adult ARDS patients requiring V-V ECMO. The assessment of LUS involved examining specific dorsal lung regions, encompassing 16 areas, during three pre-defined time points: baseline (10 minutes prior), three-hour PP positioning, and 10-minute post-supine repositioning, all within the initial three days. Based on the oxygenation response to PP, patients were categorized into responder and non-responder groups. The primary outcome was LUS score changes during the initial three-day period. Secondary outcomes examined the impact of PP on the partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) (P/F) ratio, V-V ECMO weaning success, length of ICU stay, and hospital survival.

RESULTS

Among the enrolled patients (27 in total), 16 were responders and 11 were non-responders. In the responder group, the global LUS score underwent a significant reduction from 26.38 ± 4.965 at baseline to 20.75 ± 3.337 (p < 0.001) after the first PP session, which further decreased to 15.94 ± 2.816 (p< 0.001) after three days. However, no significant differences were observed among PP non-responders. The oxygenation reaction yielded comparable results. There was a significant correlation between the duration of daily PP and the reduction in global LUS score among PP responders (r = -0.855, p < 0.001). In cases where the global LUS score decreased by > 7.5 after three days of PP, the area under the receiver operating characteristic curve (AUROC) for predicting ECMO weaning success was 0.815, while it was 0.761 for predicting hospital survival.

CONCLUSION

LUS has the potential to predict the response to PP and evaluate the prognosis of ARDS patients with V-V ECMO, although more studies are demanded in the future.

Ventilation during extracorporeal gas exchange in acute respiratory distress syndrome

PURPOSE OF REVIEW

Accumulating evidence ascribes the benefit of extracorporeal gas exchange, at least in most severe cases, to the provision of a lung healing environment through the mitigation of ventilator-induced lung injury (VILI) risk. In spite of pretty homogeneous criteria for extracorporeal gas exchange application (according to the degree of hypoxemia/hypercapnia), ventilatory management during extracorporeal membrane oxygenation (ECMO)/carbon dioxide removal (ECCO 2 R) varies across centers. Here we summarize the recent evidence regarding the management of mechanical ventilation during extracorporeal gas exchange for respiratory support.

RECENT FINDINGS

At present, the most common approach to protect the native lung against VILI following ECMO initiation involves lowering tidal volume and driving pressure, making modest reductions in respiratory rate, while typically maintaining positive end-expiratory pressure levels unchanged.Regarding ECCO 2 R treatment, higher efficiency devices are required in order to reduce significantly respiratory rate and/or tidal volume.

SUMMARY

The best compromise between reduction of native lung ventilatory load, extracorporeal gas exchange efficiency, and strategies to preserve lung aeration deserves further investigation.

Effects of different positive end-expiratory pressure titration strategies on mechanical power during ultraprotective ventilation in ARDS patients treated with veno-venous extracorporeal membrane oxygenation: A prospective interventional study

PURPOSE

Ultraprotective ventilation in acute respiratory distress syndrome (ARDS) patients with veno-venous extracorporeal membrane oxygenation (VV ECMO) reduces mechanical power (MP) through changes in positive end-expiratory pressure (PEEP); however, the optimal approach to titrate PEEP is unknown. This study assesses the effects of three PEEP titration strategies on MP, hemodynamic parameters, and oxygen delivery in twenty ARDS patients with VV ECMO.

MATERIAL AND METHODS

PEEP was titrated according to: (A) a PEEP of 10 cmH2O representing the lowest recommendation by the Extracorporeal Life Support Organization (PEEPELSO), (B) the highest static compliance of the respiratory system (PEEPCstat,RS), and (C) a target end-expiratory transpulmonary pressure of 0 cmH2O (PEEPPtpexp).

RESULTS

PEEPELSO was lower compared to PEEPCstat,RS and PEEPPtpexp (10.0 ± 0.0 vs. 16.2 ± 4.7 cmH2O and 17.3 ± 4.0 cmH2O, p < 0.001 each, respectively). PEEPELSO reduced MP compared to PEEPCstat,RS and PEEPPtpexp (5.3 ± 1.3 vs. 6.8 ± 2.0 and 6.9 ± 2.3 J/min, p < 0.001 each, respectively). PEEPELSO resulted in less lung stress compared to PEEPCstat,RS (p = 0.011) and PEEPPtpexp (p < 0.001) and increased cardiac output and oxygen delivery (p < 0.001 each).

CONCLUSIONS

An empirical PEEP of 10 cmH2O minimized MP, provided favorable hemodynamics, and increased oxygen delivery in ARDS patients treated with VV ECMO.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00013967). Registered 02/09/2018https://drks.de/search/en/trial/DRKS00013967.

Chest CT findings in severe acute respiratory distress syndrome requiring V-V ECMO: J-CARVE registry

BACKGROUND

Chest computed tomography findings are helpful for understanding the pathophysiology of severe acute respiratory distress syndrome (ARDS). However, there is no large, multicenter, chest computed tomography registry for patients requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). The aim of this study was to describe chest computed tomography findings at V-V ECMO initiation and to evaluate the association between the findings and outcomes in severe ARDS.

METHODS

This multicenter, retrospective cohort study enrolled patients with severe ARDS on V-V ECMO, who were admitted to the intensive care units of 24 hospitals in Japan between January 1, 2012, and December 31, 2022.

RESULTS

The primary outcome was 90-day in-hospital mortality. The secondary outcomes were the successful liberation from V-V ECMO and the values of static lung compliance. Among the 697 registry patients, of the 582 patients who underwent chest computed tomography at V-V ECMO initiation, 394 survived and 188 died. Multivariate Cox regression showed that traction bronchiectasis and subcutaneous emphysema increased the risk of 90-day in-hospital mortality (hazard ratio [95% confidence interval] 1.77 [1.19-2.63], p = 0.005 and 1.97 [1.02-3.79], p = 0.044, respectively). The presence of traction bronchiectasis was also associated with decreased successful liberation from V-V ECMO (odds ratio: 0.27 [0.14-0.52], p < 0.001). Lower static lung compliance was associated with some chest computed tomography findings related to changes outside of pulmonary opacity, but not with the findings related to pulmonary opacity.

CONCLUSIONS

Traction bronchiectasis and subcutaneous emphysema increased the risk of 90-day in-hospital mortality in patients with severe ARDS who required V-V ECMO.

Prone Positioning During Extracorporeal Membrane Oxygenation in Patients With Severe ARDS: The PRONECMO Randomized Clinical Trial

Importance

Prone positioning may improve outcomes in patients with severe acute respiratory distress syndrome (ARDS), but it is unknown whether prone positioning improves clinical outcomes among patients with ARDS who are undergoing venovenous extracorporeal membrane oxygenation (VV-ECMO) compared with supine positioning.

Objective

To test whether prone positioning vs supine positioning decreases the time to successful ECMO weaning in patients with severe ARDS supported by VV-ECMO.

Design, Setting, and Participants

Randomized clinical trial of patients with severe ARDS undergoing VV-ECMO for less than 48 hours at 14 intensive care units (ICUs) in France between March 3, 2021, and December 7, 2021.

Interventions

Patients were randomized 1:1 to prone positioning (at least 4 sessions of 16 hours) (n = 86) or to supine positioning (n = 84).

Main Outcomes and Measures

The primary outcome was time to successful ECMO weaning within 60 days following randomization. Secondary outcomes included ECMO and mechanical ventilation-free days, ICU and hospital length of stay, skin pressure injury, serious adverse events, and all-cause mortality at 90-day follow-up.

Results

Among 170 randomized patients (median age, 51 [IQR, 43-59] years; n = 60 women [35%]), median respiratory system compliance was 15.0 (IQR, 10.7-20.6) mL/cm H2O; 159 patients (94%) had COVID-19-related ARDS; and 164 (96%) were in prone position before ECMO initiation. Within 60 days of enrollment, 38 of 86 patients (44%) had successful ECMO weaning in the prone ECMO group compared with 37 of 84 (44%) in the supine ECMO group (risk difference, 0.1% [95% CI, -14.9% to 15.2%]; subdistribution hazard ratio, 1.11 [95% CI, 0.71-1.75]; P = .64). Within 90 days, no significant difference was observed in ECMO duration (28 vs 32 days; difference, -4.9 [95% CI, -11.2 to 1.5] days; P = .13), ICU length of stay, or 90-day mortality (51% vs 48%; risk difference, 2.4% [95% CI, -13.9% to 18.6%]; P = .62). No serious adverse events were reported during the prone position procedure.

Conclusions and Relevance

Among patients with severe ARDS supported by VV-ECMO, prone positioning compared with supine positioning did not significantly reduce time to successful weaning of ECMO.

Trial Registration

ClinicalTrials.gov Identifier: NCT04607551.

[Ventilatory management of SARS-CoV-2 acute respiratory failure]

COVID-19 pneumonia presents several particularities in its clinical presentation (cytokine storm, silent hypoxemia, thrombo-embolic risk) and may lead to a number of acute respiratory distress syndrome (ARDS) phenotypes. While the optimal oxygenation strategy in cases of hypoxemic acute respiratory failure (ARF) is still under debate, ventilatory management of COVID-19-related ARF has confirmed the efficacy of high-flow oxygen therapy and restored interest in other ventilatory approaches such as continuous positive airway pressure (CPAP) and noninvasive ventilation involving a helmet, which due to patient overflow are sometimes implemented outside of critical care units. However, further studies are still needed to determine which patients should be given which oxygenation technique, and under which conditions they require invasive mechanical ventilation, given that delayed initiation potentially burdens prognosis. During invasive mechanical ventilation, ventral decubitus and extracorporeal membrane oxygenation have become increasingly prevalent. While innovative therapies such as awake prone position or lung transplantation have likewise been developed, their indications, modalities and efficacy remain to be determined.

Liberation From Venovenous Extracorporeal Membrane Oxygenation for Respiratory Failure: A Scoping Review

BACKGROUND

Safe and timely liberation from venovenous extracorporeal membrane oxygenation (ECMO) would be expected to reduce the duration of ECMO, the risk of complications, and costs. However, how to liberate patients from venovenous ECMO effectively remains understudied.

RESEARCH QUESTION

What is the current state of the evidence on liberation from venovenous ECMO?

STUDY DESIGN AND METHODS

We systematically searched for relevant publications on liberation from venovenous ECMO in Medline and EMBASE. Citations were included if the manuscripts provided any of the following: criteria for readiness for liberation, a liberation protocol, or a definition of successful decannulation or decannulation failure. We included randomized trials, observational trials, narrative reviews, guidelines, editorials, and commentaries. We excluded single case reports and citations where the full text was unavailable.

RESULTS

We screened 1,467 citations to identify 39 key publications on liberation from venovenous ECMO. We then summarized the data into five main topics: current strategies used for liberation, criteria used to define readiness for liberation, conducting liberation trials, criteria used to proceed with decannulation, and parameters used to predict decannulation outcomes.

INTERPRETATION

Practices on liberation from venovenous ECMO are heterogeneous and are influenced strongly by clinician preference. Additional research on liberation thresholds is needed to define optimal liberation strategies and to close existing knowledge gaps in essential topics on liberation from venovenous ECMO.

Venovenous extracorporeal membrane oxygenation for COVID-19 and influenza H1N1 associated acute respiratory distress syndrome: A comparative cohort study in China

Background

Venovenous extracorporeal membrane oxygenation (VV-ECMO) has been demonstrated to be effective in treating patients with virus-induced acute respiratory distress syndrome (ARDS). However, whether the management of ECMO is different in treating H1N1 influenza and coronavirus disease 2019 (COVID-19)-associated ARDS patients remains unknown.

Methods

This is a retrospective cohort study. We included 12 VV-ECMO-supported COVID-19 patients admitted to The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Eighth People's Hospital, and Wuhan Union Hospital West Campus between January 23 and March 31, 2020. We retrospectively included VV-ECMO-supported patients with COVID-19 and H1N1 influenza-associated ARDS. Clinical characteristics, respiratory mechanics including plateau pressure, driving pressure, mechanical power, ventilatory ratio (VR) and lung compliance, and outcomes were compared.

Results

Data from 25 patients with COVID-19 (n=12) and H1N1 (n=13) associated ARDS who had received ECMO support were analyzed. COVID-19 patients were older than H1N1 influenza patients (P=0.004). The partial pressure of arterial carbon dioxide (PaCO2) and VR before ECMO initiation were significantly higher in COVID-19 patients than in H1N1 influenza patients (P <0.001 and P=0.004, respectively). COVID-19 patients showed increased plateau and driving pressure compared with H1N1 subjects (P=0.013 and P=0.018, respectively). Patients with COVID-19 remained longer on ECMO support than did H1N1 influenza patients (P=0.015). COVID-19 patients who required ECMO support also had fewer intensive care unit and ventilator-free days than H1N1.

Conclusions

Compared with H1N1 influenza patients, COVID-19 patients were older and presented with increased PaCO2 and VR values before ECMO initiation. The differences between ARDS patients with COVID-19 and influenza on VV-ECMO detailed herein could be helpful for obtaining a better understanding of COVID-19 and for better clinical management.

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.

Association between pediatric intensive care mortality and mechanical ventilation settings during extracorporeal membrane oxygenation for pediatric acute respiratory distress syndrome

The main objective of this study was to describe the current mechanical ventilation (MV) settings during extracorporeal membrane oxygenation (ECMO) for pediatric acute respiratory distress syndrome (P-ARDS) in six European centers. This is a retrospective observational cohort study performed in six European centers from January 2009 to December 2019. Children > 1 month to 18 years supported with ECMO for refractory P-ARDS were included. Collected data were as follows: patients' pre-ECMO medical condition, pre-ECMO adjunctive therapies for P-ARDS, pre-ECMO and during ECMO MV settings on day (D) 1, D3, D7, and D14 of ECMO, use of adjunctive therapies during ECMO, duration of ECMO, pediatric intensive care unit length of stay, and survival. A total of 255 patients with P-ARDS were included. The multivariate analysis showed that PEEP on D1 (OR = 1.13, 95% CI [1.03-1.24], p = 0.01); D3 (OR = 1.17, 95% CI [1.06-1.29], p = 0.001); and D14 (OR = 1.21, 95% CI [1.05-1.43], p = 0.02) and DP on D7 were significantly associated with higher odds of mortality (OR = 0.82, 95% CI [0.71-0.92], p = 0.001). Moreover, DP on D1 above 15 cmH2O (OR 2.23, 95% CI (1.09-4.71), p = 0.03) and native lung FiO2 above 60% on D14 (OR 10.36, 95% CI (1.51-116.15), p = 0.03) were significantly associated with higher odds of mortality.   Conclusion: MV settings during ECMO for P-ARDS varied among centers; however, use of high PEEP levels during ECMO was associated with higher odds of mortality as well as a DP above 15 cmH2O and a native lung FiO2 above 60% on D14 of ECMO. What is Known: • Invasive ventilation settings are well defined for pediatric acute respiratory distress syndrome; however, once the children required an extracorporeal respiratory support, there is no recommendation how to set the mechanical ventilator. • Impact of invasive ventilator during extracorporeal respiratory support ad only been during the first days of this support but the effects of these settings later in the assistance are not described. What is New: • It seems to be essential to early decrease FiO2 on native lung once the ECMO flow allows an efficient oxygenation. • Tight control to limit the driving pressure at 15 cmH20 during ECMO run seems to be associated with better survival rate.

Diaphragm function in patients with Covid-19-related acute respiratory distress syndrome on venovenous extracorporeal membrane oxygenation

BACKGROUND

Venovenous extracorporeal membrane oxygenation (VV ECMO) is frequently associated with deep sedation and neuromuscular blockades, that may lead to diaphragm dysfunction. However, the prevalence, risk factors, and evolution of diaphragm dysfunction in patients with VV ECMO are unknown. We hypothesized that the prevalence of diaphragm dysfunction is high and that diaphragm activity influences diaphragm function changes.

METHODS

Patients with acute respiratory distress syndrome (ARDS) requiring VV ECMO were included in two centers. Diaphragm function was serially assessed by measuring the tracheal pressure in response to phrenic nerve stimulation (Ptr,stim) from ECMO initiation (Day 1) until ECMO weaning. Diaphragm activity was estimated from the percentage of spontaneous breathing ventilation and by measuring the diaphragm thickening fraction (TFdi) with ultrasound.

RESULTS

Sixty-three patients were included after a median of 4 days (3-6) of invasive mechanical ventilation. Diaphragm dysfunction, defined by Ptr, stim ≤ 11 cmH2O, was present in 39 patients (62%) on Day 1 of ECMO. Diaphragm function did not change over the study period and was not influenced by the percentage of spontaneous breathing ventilation or the TFdi during the 1 week. Among the 63 patients enrolled in the study, 24 (38%) were still alive at the end of the study period (60 days).

CONCLUSIONS

Sixty-two percent of patients undergoing ECMO for ARDS related to SARS CoV-2 infection had a diaphragm dysfunction on Day 1 of ECMO initiation. Diaphragm function remains stable over time and was not associated with the percentage of time with spontaneous breathing.

CLINICALTRIALS

gov Identifier NCT04613752 (date of registration February 15, 2021).

Mortality in Patients with Obesity and Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation: The Multicenter ECMObesity Study

Rationale: Patients with obesity are at increased risk for developing acute respiratory distress syndrome (ARDS). Some centers consider obesity a relative contraindication to receiving extracorporeal membrane oxygenation (ECMO) support, despite growing implementation of ECMO for ARDS in the general population. Objectives: To investigate the association between obesity and mortality in patients with ARDS receiving ECMO. Methods: In this large, international, multicenter, retrospective cohort study, we evaluated the association of obesity, defined as body mass index ⩾ 30 kg/m2, with ICU mortality in patients receiving ECMO for ARDS by performing adjusted multivariable logistic regression and propensity score matching. Measurements and Main Results: Of 790 patients with ARDS receiving ECMO in our study, 320 had obesity. Of those, 24.1% died in the ICU, compared with 35.3% of patients without obesity (P < 0.001). In adjusted models, obesity was associated with lower ICU mortality (odds ratio, 0.63 [95% confidence interval, 0.43-0.93]; P = 0.018). Examined as a continuous variable, higher body mass index was associated with decreased ICU mortality in multivariable regression (odds ratio, 0.97 [95% confidence interval, 0.95-1.00]; P = 0.023). In propensity score matching of 199 patients with obesity to 199 patients without, patients with obesity had a lower probability of ICU death than those without (22.6% vs. 35.2%; P = 0.007). Conclusions: Among patients receiving ECMO for ARDS, those with obesity had lower ICU mortality than patients without obesity in multivariable and propensity score matching analyses. Our findings support the notion that obesity should not be considered a general contraindication to ECMO.

Retrospective analysis of factors associated with outcome in veno-venous extra-corporeal membrane oxygenation

BACKGROUND

The outcome of Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO) in acute respiratory failure may be influenced by patient-related factors, center expertise and modalities of mechanical ventilation (MV) during ECMO. We determined, in a medium-size ECMO center in Switzerland, possible factors associated with mortality during VV-ECMO for acute respiratory failure of various etiologies.

METHODS

We retrospectively analyzed all patients treated with VV-ECMO in our University Hospital from 2012 to 2019 (pre-COVID era). Demographic variables, severity scores, MV duration before ECMO, pre and on-ECMO arterial blood gases and respiratory variables were collected. The primary outcome was ICU mortality. Data were compared between survivors and non-survivors, and factors associated with mortality were assessed in univariate and multivariate analyses.

RESULTS

Fifty-one patients (33 ARDS, 18 non-ARDS) were included. ICU survival was 49% (ARDS, 39%; non-ARDS 67%). In univariate analyses, a higher driving pressure (DP) at 24h and 48h on ECMO (whole population), longer MV duration before ECMO and higher DP at 24h on ECMO (ARDS patients), were associated with mortality. In multivariate analyses, ECMO indication, higher DP at 24h on ECMO and, in ARDS, longer MV duration before ECMO, were independently associated with mortality.

CONCLUSIONS

DP on ECMO and longer MV duration before ECMO (in ARDS) are major, and potentially modifiable, factors influencing outcome during VV-ECMO.