Ultra-lung-protective ventilation and biotrauma in severe ARDS patients on veno-venous extracorporeal membrane oxygenation: a randomized controlled study

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.

Association Between Tidal Volume in Invasive Mechanical Ventilation and Mortality in Children With Extracorporeal Membrane Oxygenation

Mechanical ventilation (MV) strategies in children on extracorporeal membrane oxygenation (ECMO) have not been studied much and the ventilatory parameters to avoid greater lung damage are still unclear. Our objective was to determine the relationship between conventional tidal volume (4-8 ml/kg, CTV) versus low tidal volume (<4 ml/kg, LTV) and mortality in children with MV at the beginning of ECMO. This was a retrospective cohort study that included 101 (10.9 months interquartile range [IQR]: 6.0-24.0) children. Children with LTV had greater odds of hospital mortality (adjusted odds ratio [aOR]: 2.45; 95% confidence interval [CI]: 1.05-5.71; p = 0.03) regardless of age, reason for ECMO, and disease severity, as well as a longer duration of MV after ECMO. We found no differences between the groups in other MV settings. The CTV group required fewer fibrobronchoscopies than patients with LTV (aOR: 0.38; 95% CI: 0.15-0.99; p = 0.04). We found that a tidal volume (V T ) lower than 4 ml/kg at the onset of ECMO support in children with MV was associated with higher odds of mortality, longer post-decannulation ventilation, and a greater need for fibrobronchoscopies. Lung-protective bundles in patients with ECMO and MV should consider the V T to maintain plateau and driving pressure that avoid major lung injury caused by MV.

Managing Refractory Hypoxemia in Acute Respiratory Distress Syndrome Obese Patients with Veno-Venous Extra-Corporeal Membrane Oxygenation: A Narrative Review

Veno-venous extracorporeal membrane oxygenation (vvECMO) is a life-saving intervention for severe respiratory failure unresponsive to conventional therapies. However, managing refractory hypoxemia in morbidly obese patients poses significant challenges due to the unique physiological characteristics of this population, including hyperdynamic circulation, elevated cardiac output, and increased oxygen consumption. These factors can limit the effectiveness of vvECMO by diluting arterial oxygen content and complicating oxygen delivery. Refractory hypoxemia in obese patients supported by vvECMO often stems from an imbalance between ECMO blood flow and cardiac output. Hyperdynamic circulation exacerbates the recirculation of oxygenated blood and impairs the efficiency of oxygen transfer. To address these challenges, a stepwise, individualized approach is essential. Strategies to reduce oxygen consumption include deep sedation, neuromuscular blockade, and temperature control. Cardiac output modulation can be achieved through beta-blockers and cautious therapeutic hypothermia. Optimizing oxygen delivery involves improving residual lung function; high positive end-expiratory pressure ventilation guided by esophageal pressure monitoring; prone positioning; and adjustments to the ECMO circuit, such as using dual oxygenators, larger membranes, or additional drainage cannulas. This review highlights the interplay of physiological adaptations and technical innovations required to overcome the challenges of managing refractory hypoxemia in obese patients during vvECMO. By addressing the complexities of high cardiac output and obesity, clinicians can enhance the effectiveness of vvECMO and improve outcomes for this high-risk population.

Gene expression profiles in respiratory settings in rats under extracorporeal membrane oxygenation

Background

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is an effective lung protection strategy that avoids ventilator-induced lung injury. However, appropriate respiratory settings for VV-ECMO are yet to be established. This study aimed to elucidate the effects of ventilation under VV-ECMO using a newly developed rat VV-ECMO model and analyzed gene expression profiles.

Methods

Rats were assigned to three groups of five rats each: spontaneous breathing, conventional-protective ventilation, and ultra-protective ventilation. The conventional protective and ultraprotective ventilation groups received volume-controlled ventilation at a frequency of 60 and 20 beats/min, with tidal volumes of 6 and 3 mL/kg, respectively. VV-ECMO was performed at a pump flow rate of 20-30 mL/kg/min. At 120 min post initiation of VV-ECMO, rats were euthanized, and their lungs were harvested. Changes in gene expression were assessed using microarray analysis.

Results

Gene expression profile analyses revealed lowest expression of inflammation/immune promotion, cytotoxicity, and cell proliferation related genes (Defa5, Prg2, Siglec8, Atf3, Rnd1, Ctsg, and Gc), and the highest expression of inflammation/immune suppression related genes (Pp2d1) in the spontaneous breathing group as compared to that in the other two mechanical ventilation groups.

Conclusions

The findings of this study demonstrated that spontaneous breathing was the least invasive respiratory setting under VV-ECMO. Further, mechanical ventilation may be associated with lung injury even at low ventilation frequency and tidal volume.

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.

Methods for determining optimal positive end-expiratory pressure in patients undergoing invasive mechanical ventilation: a scoping review

PURPOSE

There is significant variability in the application of positive end-expiratory pressure (PEEP) in patients undergoing invasive mechanical ventilation. There are numerous studies assessing methods of determining optimal PEEP, but many methods, patient populations, and study settings lack high-quality evidence. Guidelines make no recommendations about the use of a specific method because of equipoise and lack of high-quality evidence. We conducted a scoping review to determine which methods of determining optimal PEEP have been studied and what gaps exist in the literature.

SOURCE

We searched five databases for primary research reports studying methods of determining optimal PEEP among adults undergoing invasive mechanical ventilation. Data abstracted consisted of the titration method, setting, study design, population, and outcomes.

PRINCIPLE FINDINGS

Two hundred and seventy-one studies with 17,205 patients met the inclusion criteria, including 73 randomized controlled trials (RCTs) with 10,733 patients. We identified 22 methods. Eleven were studied with an RCT. Studies enrolled participants within an intensive care unit (ICU) (216/271, 80%) or operating room (55/271, 20%). Most ICU studies enrolled patients with acute respiratory distress syndrome (162/216, 75%). The three most studied methods were compliance (73 studies, 29 RCTs), imaging-based methods (65 studies, 11 RCTs), and use of PEEP-FIO2 tables (52 studies, 20 RCTs). Among ICU RCTs, the most common primary outcomes were mortality or oxygenation. Few RCTs assessed feasibility of different methods (n = 3). The strengths and limitations of each method are discussed.

CONCLUSION

Numerous methods of determining optimal PEEP have been evaluated; however, notable gaps remain in the evidence supporting their use. These include specific populations (normal lungs, patients weaning from mechanical ventilation) and using alternate outcomes (ventilator-free days and feasibility) and they present significant opportunities for future study.

STUDY REGISTRATION

Open Science Framework ( https://osf.io/atzqc ); first posted, 19 July 2022.

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.

Comparison of venovenous extracorporeal membrane oxygenation, prone position and supine mechanical ventilation for severely hypoxemic acute respiratory distress syndrome: a network meta-analysis

PURPOSE

Severe acute respiratory distress syndrome (ARDS) with PaO2/FiO2 < 80 mmHg is a life-threatening condition. The optimal management strategy is unclear. The aim of this meta-analysis was to compare the effects of low tidal volumes (Vt), moderate Vt, prone ventilation, and venovenous extracorporeal membrane oxygenation (VV-ECMO) on mortality in severe ARDS.

METHODS

We performed a frequentist network meta-analysis of randomised controlled trials (RCTs) with participants who had severe ARDS and met eligibility criteria for VV-ECMO or had PaO2/FiO2 < 80 mmHg. We applied the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology to discern the relative effect of interventions on mortality and the certainty of the evidence.

RESULTS

Ten RCTs including 812 participants with severe ARDS were eligible. VV-ECMO reduces mortality compared to low Vt (risk ratio [RR] 0.77, 95% confidence interval [CI] 0.59-0.99, moderate certainty) and compared to moderate Vt (RR 0.75, 95% CI 0.57-0.98, low certainty). Prone ventilation reduces mortality compared to moderate Vt (RR 0.78, 95% CI 0.66-0.93, high certainty) and compared to low Vt (RR 0.81, 95% CI 0.63-1.02, moderate certainty). We found no difference in the network comparison of VV-ECMO compared to prone ventilation (RR 0.95, 95% CI 0.72-1.26), but inferences were based solely on indirect comparisons with very low certainty due to very wide confidence intervals.

CONCLUSIONS

In adults with ARDS and severe hypoxia, both VV-ECMO (low to moderate certainty evidence) and prone ventilation (moderate to high certainty evidence) improve mortality relative to low and moderate Vt strategies. The impact of VV-ECMO versus prone ventilation remains uncertain.

Web-based Dashboard on ECMO Utilization in Germany: An Interactive Visualization, Analyses, and Prediction Based on Real-life Data

In Germany, a comprehensive reimbursement policy for extracorporeal membrane oxygenation (ECMO) results in the highest per capita use worldwide, although benefits remain controversial. Public ECMO data is unstructured and poorly accessible to healthcare professionals, researchers, and policymakers. In addition, there are no uniform policies for ECMO allocation which confronts medical personnel with ethical considerations during health crises such as respiratory virus outbreaks.Retrospective information on adult and pediatric ECMO support performed in German hospitals was extracted from publicly available reimbursement data and hospital quality reports and processed to create the web-based ECMO Dashboard built on Open-Source software. Patient-level and hospital-level data were merged resulting in a solid base for ECMO use analysis and ECMO demand forecasting with high spatial granularity at the level of 413 county and city districts in Germany.The ECMO Dashboard ( https://www.ecmo-dash.de/ ), an innovative visual platform, presents the retrospective utilization patterns of ECMO support in Germany. It features interactive maps, comprehensive charts, and tables, providing insights at the hospital, district, and national levels. This tool also highlights the high prevalence of ECMO support in Germany and emphasizes districts with ECMO surplus - where patients from other regions are treated, or deficit - origins from which ECMO patients are transferred to other regions. The dashboard will evolve iteratively to provide stakeholders with vital information for informed and transparent resource allocation and decision-making.Accessible public routine data could support evidence-informed, forward-looking resource management policies, which are urgently needed to increase the quality and prepare the critical care infrastructure for future pandemics.

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.

PEBP4 deficiency aggravates LPS-induced acute lung injury and alveolar fluid clearance impairment via modulating PI3K/AKT signaling pathway

Acute lung injury (ALI) is a common clinical syndrome, which often results in pulmonary edema and respiratory distress. It has been recently reported that phosphatidylethanolamine binding protein 4 (PEBP4), a basic cytoplasmic protein, has anti-inflammatory and hepatoprotective effects, but its relationship with ALI remains undefined so far. In this study, we generated PEBP4 knockout (KO) mice to investigate the potential function of PEBP4, as well as to evaluate the capacity of alveolar fluid clearance (AFC) and the activity of phosphatidylinositide 3-kinases (PI3K)/serine-theronine protein kinase B (PKB, also known as AKT) signaling pathway in lipopolysaccharide (LPS)-induced ALI mice models. We found that PEBP4 deficiency exacerbated lung pathological damage and edema, and increased the wet/dry weight ratio and total protein concentration of bronchoalveolar lavage fluid (BALF) in LPS-treated mice. Meanwhile, PEBP4 KO promoted an LPS-induced rise in the pulmonary myeloperoxidase (MPO) activity, serum interleuin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α levels, and pulmonary cyclooxygenase-2 (COX-2) expression. Mechanically, PEBP4 deletion further reduced the protein expression of Na+ transport markers, including epithelial sodium channel (ENaC)-α, ENaC-γ, Na,K-ATPase α1, and Na,K-ATPase β1, and strengthened the inhibition of PI3K/AKT signaling in LPS-challenged mice. Furthermore, we demonstrated that selective activation of PI3K/AKT with 740YP or SC79 partially reversed all of the above effects caused by PEBP4 KO in LPS-treated mice. Altogether, our results indicated the PEBP4 deletion has a deterioration effect on LPS-induced ALI by impairing the capacity of AFC, which may be achieved through modulating the PI3K/AKT pathway.

Pulmonary inflammation decreases with ultra-protective ventilation in experimental ARDS under VV-ECMO: a positron emission tomography study

Background

Experimentally, ultra-protective ventilation (UPV, tidal volumes [VT] < 4 mL.kg-1) strategies in conjunction with veno-venous extracorporeal membrane oxygenation (VV-ECMO) are associated with lesser ventilator-induced lung injuries (VILI) during acute respiratory distress syndrome (ARDS). However, whether these strategies reduce lung inflammation more effectively than protective ventilation (PV) remains unclear. We aimed to demonstrate that a UPV strategy decreases acute lung inflammation in comparison with PV in an experimental swine model of ARDS.

Methods

ARDS was induced by tracheal instillation of chlorhydric acid in sedated and paralyzed animals under mechanical ventilation. Animals were randomized to receive either UPV (VT 1 mL.kg-1, positive end-expiration pressure [PEEP] set to obtain plateau pressure between 20 and 25 cmH2O and respiratory rate [RR] at 5 min-1 under VV-ECMO) or PV (VT 6 mL.kg-1, PEEP set to obtain plateau pressure between 28 and 30 cmH2O and RR at 25 min-1) during 4 h. After 4 h, a positron emission tomography with [11C](R)-PK11195 (ligand to TSPO-bearing macrophages) injection was realized, coupled with quantitative computerized tomography (CT). Pharmacokinetic multicompartment models were used to quantify regional [11C](R)-PK11195 lung uptake. [11C](R)-PK11195 lung uptake and CT-derived respiratory variables were studied regionally across eight lung regions distributed along the antero-posterior axis.

Results

Five pigs were randomized to each study group. Arterial O2 partial pressure to inspired O2 fraction were not significantly different between study groups after experimental ARDS induction (75 [68-80] mmHg in a PV group vs. 87 [69-133] mmHg in a UPV group, p = 0.20). Compared to PV animals, UPV animals exhibited a significant decrease in the regional non-aerated compartment in the posterior lung levels, in mechanical power, and in regional dynamic strain and no statistical difference in tidal hyperinflation after 4 h. UPV animals had a significantly lower [11C](R)-PK11195 uptake, compared to PV animals (non-displaceable binding potential 0.35 [IQR, 0.20-0.59] in UPV animals and 1.01 [IQR, 0.75-1.59] in PV animals, p = 0.01). Regional [11C](R)-PK11195 uptake was independently associated with the interaction of regional tidal hyperinflation and regional lung compliance.

Conclusion

In an experimental model of ARDS, 4 h of UPV strategy significantly decreased lung inflammation, in relation to the control of VT-derived determinants of VILI.

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.

Association between mechanical ventilation parameters and mortality in children with respiratory failure on ECMO: a systematic review and meta-analysis

Background

In refractory respiratory failure (RF), extracorporeal membrane oxygenation (ECMO) is a salvage therapy that seeks to reduce lung injury induced by mechanical ventilation. The parameters of optimal mechanical ventilation in children during ECMO are not known. Pulmonary ventilatory management during this therapy may impact mortality. The objective of this study was to evaluate the association between ventilatory parameters in children during ECMO therapy and in-hospital mortality.

Methods

A systematic search of PubMed/MEDLINE, Embase, Cochrane, and Google Scholar from January 2013 until May 2022 (PROSPERO 450744), including studies in children with ECMO-supported RF assessing mechanical ventilation parameters, was conducted. Risk of bias was assessed using the Newcastle-Ottawa scale; heterogeneity, with absence <25% and high >75%, was assessed using I2. Sensitivity and subgroup analyses using the Mantel-Haenszel random-effects model were performed to explore the impact of methodological quality on effect size.

Results

Six studies were included. The median age was 3.4 years (IQR: 3.2-4.2). Survival in the 28-day studies was 69%. Mechanical ventilation parameters associated with higher mortality were a very low tidal volume ventilation (<4 ml/kg; OR: 4.70; 95% CI: 2.91-7.59; p < 0.01; I2: 38%), high plateau pressure (mean Dif: -0.70 95% CI: -0.18, -0.22; p < 0.01), and high driving pressure (mean Dif: -0.96 95% CI: -1.83, -0.09: p = 0.03). The inspired fraction of oxygen (p = 0.09) and end-expiratory pressure (p = 0.69) were not associated with higher mortality. Patients who survived had less multiple organ failure (p < 0.01).

Conclusion

The mechanical ventilation variables associated with higher mortality in children with ECMO-supported respiratory failure are high plateau pressures, high driving pressure and very low tidal volume ventilation. No association between mortality and other parameters of the mechanical ventilator, such as the inspired fraction of oxygen or end-expiratory pressure, was found.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023450744, PROSPERO 2023 (CRD42023450744).

Mechanical ventilation during pediatric extracorporeal life support

PURPOSE OF REVIEW

To discuss the role of ventilator induced lung injury (VILI) and patient self-inflicted lung injury in ventilated children supported on extracorporeal membrane oxygenation (ECMO).

RECENT FINDINGS

While extracorporeal life support is used routinely used every day around the globe to support neonatal, pediatric, and adult patients with refractory cardiac and/or respiratory failure, the optimal approach to mechanical ventilation, especially for those with acute respiratory distress syndrome (ARDS), remains unknown and controversial. Given the lack of definitive data in this population, one must rely on available evidence in those with ARDS not supported with ECMO and extrapolate adult observations. Ventilatory management should include, as a minimum standard, limiting inspiratory and driving pressures, providing a sufficient level of positive end-expiratory pressure, and setting a low rate to reduce mechanical power. Allowing for spontaneous breathing and use of pulmonary specific ancillary treatment modalities must be individualized, while balancing the risk and benefits. Future studies delineating the best strategies for optimizing MV during pediatric extracorporeal life support are much needed.

SUMMARY

Future investigations will hopefully provide the needed evidence and better understanding of the overall goal of reducing mechanical ventilation intensity to decrease risk for VILI and promote lung recovery for those supported with ECMO.

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.

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.

A Systematic Review of Mortality Rates Among Adult Acute Respiratory Distress Syndrome Patients Undergoing Extracorporeal Membrane Oxygenation Therapy

Acute respiratory distress syndrome (ARDS) is a severe lung disease associated with a high mortality rate. Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for severe ARDS patients who do not respond to conventional treatments. Nevertheless, the optimal management of ARDS patients undergoing ECMO and their mortality rates remain subjects of controversy. Thus, this systematic review aims to assess mortality rates in ARDS patients on ECMO and identify associated factors. The review adhered to the Preferred Reporting Items for Systemic Review and Meta-Analysis (PRISMA) 2020 guidelines. A comprehensive literature search was conducted on PubMed, PubMed Central (PMC), Medline, and Embase. In accordance with our inclusion and exclusion criteria, filters, and key terms, we proceeded to screen the articles. After assessing the relevance of each article to our topic, further screening was carried out. Quality assessment of the articles was conducted, resulting in the inclusion of a total of 12 articles for the review. The primary outcome focused on mortality rates among ARDS patients undergoing ECMO. Secondary outcomes explored potential contributors to mortality, including patient age, underlying cause of ARDS, and Sequential Organ Failure Assessment (SOFA) scores at the initiation of ECMO. Mortality rates exhibited significant variation, ranging from 22% to 62.6%. Several factors emerged as potential predictors of mortality, encompassing patient age, comorbidities, complications during ECMO therapy, and treatment-related variables. This systematic review offers valuable insights into the intricate factors influencing mortality rates among ARDS patients on ECMO. A comprehension of these factors is essential to steer clinical practice and enhance patient outcomes. While ECMO serves as a restorative avenue for ARDS patients, future research is warranted to further elucidate these complex interactions and refine ECMO therapy protocols.

Mechanical Ventilation during ECMO: Best Practices

Adults and children who require extracorporeal membrane oxygenation for respiratory failure remain at risk for ongoing lung injury if ventilator management is not optimized. This review serves as a guide to assist the bedside clinician in ventilator titration for patients on extracorporeal membrane oxygenation, with a focus on lung-protective strategies. Existing data and guidelines for extracorporeal membrane oxygenation ventilator management are reviewed, including non-conventional ventilation modes and adjunct therapies.

Mechanical power of ventilation and driving pressure: two undervalued parameters for pre extracorporeal membrane oxygenation ventilation and during daily management?

The current ARDS guidelines highly recommend lung protective ventilation which include plateau pressure (P_plat < 30 cm H₂O), positive end expiratory pressure (PEEP > 5 cm H₂O) and tidal volume (V_t of 6 ml/kg) of predicted body weight. In contrast, the ELSO guidelines suggest the evaluation of an indication of veno-venous extracorporeal membrane oxygenation (ECMO) due to hypoxemic or hypercapnic respiratory failure or as bridge to lung transplantation. Finally, these recommendations remain a wide range of scope of interpretation. However, particularly patients with moderate-severe to severe ARDS might benefit from strict adherence to lung protective ventilation strategies. Subsequently, we discuss whether extended physiological ventilation parameter analysis might be relevant for indication of ECMO support and can be implemented during the daily routine evaluation of ARDS patients. Particularly, this viewpoint focus on driving pressure and mechanical power.