Prone-Positioning for Severe Acute Respiratory Distress Syndrome Requiring Extracorporeal Membrane Oxygenation

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.

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.

Cardiac Tamponade Complicating Extracorporeal Membrane Oxygenation: An Extracorporeal Life Support Organization Registry Analysis

OBJECTIVES

Cardiac tamponade is a potentially life-threatening complication during extracorporeal membrane oxygenation (ECMO). In this study, the authors assessed the incidence, patient characteristics, and risk factors for mortality of cardiac tamponade during ECMO.

DESIGN

The authors queried the Extracorporeal Life Support Organization (ELSO) Registry from 1997 to 2021 for all adults with cardiac tamponade as a reported complication during ECMO.

PARTICIPANTS

Cardiac tamponade was reported in 2,176 (64% men; 53.8 ± 0.33 years) of 84,430 adults (2.6%).

MEASUREMENTS AND MAIN RESULTS

Venoarterial ECMO was the main configuration (78%), followed by venovenous ECMO (VV ECMO) (18%), for cardiac (67%), pulmonary (21%) support, and extracorporeal cardiopulmonary resuscitation (ECPR) (12%). Percutaneous cannulation was performed in 51%, with the femoral vein and femoral artery as the most common sites for drainage and return cannulae, with dual-lumen cannulae in 39% of VV ECMO. Hospital survival was lower (35% v 49%; p < 0.01) when compared with that of all adults from the ELSO Registry. In multivariate analysis, age, aortic dissection and/or rupture, COVID-19, ECPR, pre-ECMO renal-replacement therapy, and prone position are associated with hospital mortality, whereas ECMO for pulmonary support is associated with hospital survival. Similarly, renal, cardiovascular, metabolic, neurologic, and pulmonary complications occurred more frequently in nonsurvivors.

CONCLUSIONS

Cardiac tamponade is a rare complication during ECMO that, despite being potentially reversible, is associated with high hospital mortality. Venoarterial ECMO is the most common configuration. ECMO for pulmonary support was associated with higher survival, and ECPR was associated with higher mortality. In these patients, other ECMO-related complications were frequently reported and associated with hospital mortality.

Pressure ulcers after prone positioning in patients undergoing extracorporeal membrane oxygenation: A cross-sectional study

BACKGROUND

The combination of prone positioning and extracorporeal membrane oxygenation (ECMO) in patients with acute respiratory distress syndrome (ARDS) is recognized as safe but its use has been limited due to potential complications.

AIM

To report the prevalence of pressure ulcers and other complications due to prone positioning in adult patients receiving veno-venous ECMO.

STUDY DESIGN

This cross-sectional study was conducted in a tertiary level intensive care unit (ICU) in Milan (Italy), between January 2015 and December 2019. The study population was critically ill adult patients undergoing veno-venous ECMO. Statistical association between pressure ulcers and the type of body positioning (prone versus supine) was explored fitting a logistic model.

RESULTS

In the study period, 114 patients were treated with veno-venous ECMO and 62 (54.4%) patients were placed prone for a total of 130 prone position cycles. ECMO cannulation was performed via femoro-femoral configuration in the majority of patients (82.4%, 94/114). Pressure ulcers developed in 57.0% of patients (95%CI: 44.0%-72.6%), most often arising on the face and the chin (37.1%, 23/62), particularly in those placed prone. The main reason of prone positioning interruption was the decrease of ECMO blood flow (8.1%, 5/62). The fitted model showed no association between body position during ECMO and occurrence of pressure ulcers (OR 1.3, 95%CI: 0.5-3.6, p = .532).

CONCLUSIONS

Facial pressure ulcers were the most frequent complications of prone positioning. Nurses should plan and implement evidence-based care to prevent such pressure injuries in patients undergoing ECMO.

RELEVANCE TO CLINICAL PRACTICE

The combination of prone positioning and ECMO shows few life-threating complications. This manoeuvre during ECMO is feasible and safe when performed by experienced ICU staff.

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.

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.

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.

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.

Setting and Monitoring of Mechanical Ventilation During Venovenous ECMO

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2023. Other selected articles can be found online at  https://www.biomedcentral.com/collections/annualupdate2023 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from  https://link.springer.com/bookseries/8901 .

Impact of Prone Position in COVID-19 Patients on Extracorporeal Membrane Oxygenation

OBJECTIVES

Prone positioning and venovenous extracorporeal membrane oxygenation (ECMO) are both useful interventions in acute respiratory distress syndrome (ARDS). Combining the two therapies is feasible and safe, but the effectiveness is not known. Our objective was to evaluate the potential survival benefit of prone positioning in venovenous ECMO patients cannulated for COVID-19-related ARDS.

DESIGN

Retrospective analysis of a multicenter cohort.

PATIENTS

Patients on venovenous ECMO who tested positive for severe acute respiratory syndrome coronavirus 2 by reverse transcriptase polymerase chain reaction or with a diagnosis on chest CT were eligible.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients on venovenous ECMO for respiratory failure in whom prone position status while on ECMO and in-hospital mortality were known were included. Of 647 patients in 41 centers, 517 were included. Median age was 55 (47-61), 78% were male and 95% were proned before cannulation. After cannulation, 364 patients (70%) were proned and 153 (30%) remained in the supine position for the whole ECMO run. There were 194 (53%) and 92 (60%) deaths in the prone and the supine groups, respectively. Prone position on ECMO was independently associated with lower in-hospital mortality (odds ratio = 0.49 [0.29-0.84]; p = 0.010). In 153 propensity score-matched pairs, mortality rate was 49.7% in the prone position group versus 60.1% in the supine position group (p = 0.085). Considering only patients alive at decannulation, propensity-matched proned patients had a significantly lower mortality rate (22.4% vs 37.8%; p = 0.029) than nonproned patients.

CONCLUSIONS

Prone position may be beneficial in patients supported by venovenous ECMO for COVID-19-related ARDS but more data are needed to draw definitive conclusions.

Timing of Prone Positioning During Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome

OBJECTIVES

To assess the association of timing to prone positioning (PP) during venovenous extracorporeal membrane oxygenation (V-V ECMO) with the probability of being discharged alive from the ICU at 90 days (primary endpoint) and the improvement of the respiratory system compliance (Cpl,rs).

DESIGN

Pooled individual data analysis from five original observational cohort studies.

SETTING

European extracorporeal membrane oxygenation (ECMO) centers.

PATIENTS

Acute respiratory distress syndrome (ARDS) patients who underwent PP during ECMO.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Time to PP during V-V ECMO was explored both as a continuous and a categorical variable with Cox proportional hazard models. Three hundred patients were included in the analysis. The longer the time to PP during V-V ECMO, the lower the adjusted probability of alive ICU discharge (adjusted hazard ratio [HR] 0.90 for each day increase; 95% CI, 0.87-0.93). Two hundred twenty-three and 77 patients were included in the early PP (≤ 5 d) and late PP (> 5 d) groups, respectively. The cumulative 90-day probability of being discharged alive from the ICU was 61% in the early PP group vs 36% in the late PP group (log-rank test, p <0.001). This benefit was maintained after adjustment for confounders (adjusted HR, 2.52; 95% CI, 1.66-3.81; p <0.001). In the early PP group, PP was associated with a significant improvement of Cpl,rs (4 ± 9 mL/cm H2O vs 0 ± 12 in the late PP group, p=0.038).

CONCLUSIONS

In a large cohort of ARDS patients on ECMO, early PP during ECMO was associated with a higher probability of being discharged alive from the ICU at 90 days and a greater improvement of Cpl,rs.

Impact of Prone Position in COVID-19 Patients on Extracorporeal Membrane Oxygenation

OBJECTIVES

Prone positioning and venovenous extracorporeal membrane oxygenation (ECMO) are both useful interventions in acute respiratory distress syndrome (ARDS). Combining the two therapies is feasible and safe, but the effectiveness is not known. Our objective was to evaluate the potential survival benefit of prone positioning in venovenous ECMO patients cannulated for COVID-19-related ARDS.

DESIGN

Retrospective analysis of a multicenter cohort.

PATIENTS

Patients on venovenous ECMO who tested positive for severe acute respiratory syndrome coronavirus 2 by reverse transcriptase polymerase chain reaction or with a diagnosis on chest CT were eligible.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients on venovenous ECMO for respiratory failure in whom prone position status while on ECMO and in-hospital mortality were known were included. Of 647 patients in 41 centers, 517 were included. Median age was 55 (47-61), 78% were male and 95% were proned before cannulation. After cannulation, 364 patients (70%) were proned and 153 (30%) remained in the supine position for the whole ECMO run. There were 194 (53%) and 92 (60%) deaths in the prone and the supine groups, respectively. Prone position on ECMO was independently associated with lower in-hospital mortality (odds ratio = 0.49 [0.29-0.84]; p = 0.010). In 153 propensity score-matched pairs, mortality rate was 49.7% in the prone position group versus 60.1% in the supine position group (p = 0.085). Considering only patients alive at decannulation, propensity-matched proned patients had a significantly lower mortality rate (22.4% vs 37.8%; p = 0.029) than nonproned patients.

CONCLUSIONS

Prone position may be beneficial in patients supported by venovenous ECMO for COVID-19-related ARDS but more data are needed to draw definitive conclusions.

Impact of prone positioning duration on the outcome of patients receiving venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: A meta-analysis

Purpose

Research has shown that prone positioning (PP) improves the survival of patients receiving venovenous extracorporeal membrane oxygenation (V-V ECMO) for acute respiratory distress syndrome (ARDS). However, the reported impact of PP duration on the outcome of V-V ECMO patients with ARDS varies across studies.

Methods

A meta-analysis approach was used to identify studies that investigated the impact of PP duration on the outcome of ARDS patients who were treated with V-V ECMO; the following databases were used: MEDLINE, Embase, Wanfang, and the China National Knowledge Infrastructure. The primary outcome was cumulative survival. Secondary outcomes were length of stay in an intensive care unit, exchange of arterial blood gases, and adverse events.

Results

A total of 8 studies were included in the final meta-analysis. Patients with longer duration of PP (≥12 h) had a longer survival period (risk ratio: 1.24; 95% confidence interval: 1.00, 1.54]) than those with PP < 12 h. There was no evidence of publication bias across the studies.

Conclusion

Our results imply that a longer duration of PP ≥ 12 h might improve the outcome of patients with ARDS who receive V-V ECMO therapy.

Prone positioning in ARDS patients supported with VV ECMO, what we should explore?

Background

Acute respiratory distress syndrome (ARDS), a prevalent cause of admittance to intensive care units, is associated with high mortality. Prone positioning has been proven to improve the outcomes of moderate to severe ARDS patients owing to its physiological effects. Venovenous extracorporeal membrane oxygenation (VV ECMO) will be considered in patients with severe hypoxemia. However, for patients with severe hypoxemia supported with VV ECMO, the potential effects and optimal strategies of prone positioning remain unclear. This review aimed to present these controversial questions and highlight directions for future research.

Main body

The clinically significant benefit of prone positioning and early VV ECMO alone was confirmed in patients with severe ARDS. However, a number of questions regarding the combination of VV ECMO and prone positioning remain unanswered. We discussed the potential effects of prone positioning on gas exchange, respiratory mechanics, hemodynamics, and outcomes. Strategies to achieve optimal outcomes, including indications, timing, duration, and frequency of prone positioning, as well as the management of respiratory drive during prone positioning sessions in ARDS patients receiving VV ECMO, are challenging and controversial. Additionally, whether and how to implement prone positioning according to ARDS phenotypes should be evaluated. Lung morphology monitored by computed tomography, lung ultrasound, or electrical impedance tomography might be a potential indication to make an individualized plan for prone positioning therapy in patients supported with VV ECMO.

Conclusion

For patients with ARDS supported with VV ECMO, the potential effects of prone positioning have yet to be clarified. Ensuring an optimal strategy, especially an individualized plan for prone positioning therapy during VV ECMO, is particularly challenging and requires further research.

Effect of prone position in patients with acute respiratory distress syndrome supported by venovenous extracorporeal membrane oxygenation: a retrospective cohort study

Background

The application of prone position (PP) in acute respiratory distress syndrome (ARDS) supported by venovenous extracorporeal membrane oxygenation (VV-ECMO) is controversial.

Objectives

To evaluate the safety and efficacy of application of PP during VV-ECMO in patients with ARDS.

Methods

This was a single-center, retrospective study of patients who met the Berlin definition of ARDS, and were supported with VV-ECMO. We divided the patients into two groups. The prone group included patients who were supported by VV-ECMO, and experienced at least one period of PP, while those without PP during VV-ECMO were defined as the supine group. Propensity score matching (PSM) at a ratio of 1:1 was introduced to minimize potential confounders. The primary outcomes were the complications of PP and the change of arterial oxygen pressure/fraction of the inspiration (PaO₂/FiO₂) ratio after PP. The secondary outcomes were hospital survival, ICU survival, and ECMO weaning rate.

Results

From April 2013 to October 2020, a total of 91 patients met the diagnostic criteria of ARDS who were supported with ECMO. 38 patients (41.8%) received at least one period of PP during ECMO, while 53 patients (58.2%) were maintained in supine position during ECMO. 22 minor complications were reported in the prone group and major complications were not found. The other ECMO-related complications were similar between two groups. The PaO₂/FiO₂ ratio significantly improved after PP compared with before (174.50 (132.40–228.25) mmHg vs. 158.00 (122.93–210.33) mmHg, p < 0.001). PSM selected 25 pairs of patients with similar characteristics. Hospital survival or ICU survival did not differ between the two groups (40% vs. 28%, p = 0.370; 40% vs. 32%, p = 0.556). Significant difference of ECMO weaning rate between two groups was not found (56% vs. 32%, p = 0.087).

Conclusions

PP during VV-ECMO was safe and could improve oxygenation. A large-scale and well-designed RCT is needed in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02026-7.

Bedside Selection of Positive End Expiratory Pressure by Electrical Impedance Tomography in Patients Undergoing Veno-Venous Extracorporeal Membrane Oxygenation Support: A Comparison between COVID-19 ARDS and ARDS from Other Etiologies

Background: The interest in protective ventilation strategies and individualized approaches for patients with severe illness on veno venous extracorporeal support has increased in recent years. Wide heterogeneity exists among patients with COVID-19 related acute respiratory distress syndrome (C-ARDS) and ARDS from other etiologies (NC-ARDS). EIT is a useful tool for the accurate analysis of regional lung volume distribution and allows for a tailored ventilatory setting. The aim of this work is to retrospectively describe the results of EIT assessments performed in patients C-ARDS and NC-ARDS undergoing V-V ECMO support. Methods: A clinical EIT-guided decremental PEEP trail was conducted for all patients included in the study and mechanically ventilated. Results: 12 patients with C-ARDS and 12 patients with NC-ARDS were included in the study for a total of 13 and 18 EIT evaluations, respectively. No significant differences in arterial blood gas, respiratory parameters, and regional ventilation before and after the EIT exam were recorded. The subset of patients with NC-ARDS whose EIT exam led to PEEP modification was characterized by a lower baseline compliance compared with the C-ARDS group: 18 (16–28) vs. 27 (24–30) (p = 0.04). Overdistension significantly increased at higher steps only for the NC-ARDS group. A higher percentage of overdistension was described in patients with NC-ARDS when compared with patients with C-ARDS. Conclusions: EIT is feasible in patients with COVID-19-associated ARDS on veno-venous extracorporeal support and may help in tailoring the PEEP setting. Overall, severe COVID-19-related ARDS presents respiratory characteristics similar to severe “classical” NC-ARDS. However, C-ARDS is associated with a lower risk of overdistension at a higher PEEP level compared with NC-ARDS.

Effect of prone positioning on survival in adult patients receiving venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a systematic review and meta-analysis

Purpose

Previous studies support the potential efficacy of venovenous extracorporeal membrane oxygenation (vvECMO) for improving survival in severe acute respiratory distress syndrome (ARDS) cases. Prone positioning (PP) has been shown to improve the outcomes of moderate-to-severe ARDS patients. Few studies and no randomized controlled trials have evaluated the effect of PP performed in ECMO patients.

Methods

We performed a systematic review and meta-analysis examining the effect of prone positioning for ARDS patients receiving vvECMO on survival. All authors were contacted to obtain complementary information not mentioned in the original articles. The main objective was to compare 28-day survival in vvECMO patients with PP to vvECMO patients without PP (controls).

Results

Thirteen studies with a combined population of 1836 patients satisfied the inclusion criteria. PP was associated with a significant improvement in 28-day survival (503 survivors among 681 patients in the PP group [74%; 95% CI 71–77] vs. 450 survivors among 770 patients in the control group [58%, 95% CI 55–62]; RR 1.31 [95% CI 1.21–1.41]; I² 22% [95% CI 0–62%]; P < 0.0001). Survival was also improved in terms of other endpoints (60-day survival, 90-day survival, ICU survival, and hospital survival). In contrast, the duration of mechanical ventilation was increased in vvECMO patients with PP (mean difference 11.4 days [95% CI 9.2–13.5]; 0.64 [95% CI 0.50–0.78]; I² 8%; P < 0.0001).

Conclusion

According to this meta-analysis, survival was improved when prone positioning was used in ARDS patients receiving vvECMO. The impact of this combination on survival should be investigated in prospective randomized controlled trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06604-x.

Effects of Prone Positioning on Respiratory Mechanics and Oxygenation in Critically Ill Patients With COVID-19 Requiring Venovenous Extracorporeal Membrane Oxygenation

Background:

The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO).

Methods:

We prospectively analyzed the effects of PP on respiratory mechanics from continuous data with over a thousand time points during 16-h PP sessions in patients with COVID-19 and ARDS under VV-ECMO conditions. The evolution of respiratory mechanical and oxygenation parameters during the PP sessions was evaluated by dividing each PP session into four time quartiles: first quartile: 0–4 h, second quartile: 4–8 h, third quartile: 8–12 h, and fourth quartile: 12–16 h.

Results:

Overall, 38 PP sessions were performed in 10 patients, with 3 [2–5] PP sessions per patient. Seven (70%) patients were responders to at least one PP session. PP significantly increased the PaO₂/FiO₂ ratio by 14 ± 21% and compliance by 8 ± 15%, and significantly decreased the oxygenation index by 13 ± 18% and driving pressure by 8 ± 12%. The effects of PP on respiratory mechanics but not on oxygenation persisted after supine repositioning. PP-induced changes in different respiratory mechanical parameters and oxygenation started as early as the first-time quartile, without any difference in PP-induced changes among the different time quartiles. PP-induced changes in driving pressure (−14 ± 14 vs. −6 ± 10%, p = 0.04) and mechanical power (−11 ± 13 vs. −0.1 ± 12%, p = 0.02) were significantly higher in responders (increase in PaO₂/FiO₂ ratio > 20%) than in non-responder patients.

Conclusions:

In patients with COVID-19 and severe ARDS, PP under VV-ECMO conditions improved the respiratory mechanical and oxygenation parameters, and the effects of PP on respiratory mechanics persisted after supine repositioning.

Prone positioning during venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a pooled individual patient data analysis

BACKGROUND

Prone positioning (PP) reduces mortality of patients with acute respiratory distress syndrome (ARDS). The potential benefit of prone positioning maneuvers during venovenous extracorporeal membrane oxygenation (ECMO) is unknown. The aim of this study was to evaluate the association between the use of prone positioning during extracorporeal support and ICU mortality in a pooled population of patients from previous European cohort studies.

METHODS

We performed a pooled individual patient data analysis of European cohort studies which compared patients treated with prone positioning during ECMO (Prone group) to "conventional" ECMO management (Supine group) in patients with severe ARDS.

RESULTS

889 patients from five studies were included. Unadjusted ICU mortality was 52.8% in the Supine Group and 40.8% in the Prone group. At a Cox multiple regression analysis PP during ECMO was not significantly associated with a reduction of ICU mortality (HR 0.67 95% CI: 0.42-1.06). Propensity score matching identified 227 patients in each group. ICU mortality of the matched samples was 48.0% and 39.6% for patients in the Supine and Prone group, respectively (p = 0.072).

CONCLUSIONS

In a large population of ARDS patients receiving venovenous extracorporeal support, the use of prone positioning during ECMO was not significantly associated with reduced ICU mortality. The impact of this procedure will have to be definitively assessed by prospective randomized controlled trials.

Combined Use of ECMO, Prone Positioning, and APRV in the Management of Severe COVID-19 Patients

Background

Severe COVID-19-associated Acute Respiratory Distress Syndrome (ARDS) may warrant extracorporeal membrane oxygenation (ECMO). We evaluated the safety and physiologic changes in oxygenation and hemodynamic profile during ECMO, prone positioning, and the two modalities combined in patients receiving veno-venous (VV) ECMO.

Methods

Cohort study of consecutive adult patients with COVID-19-associated ARDS requiring VV-ECMO, classified into three groups: ECMO support only; Prone positioning only; and Prone positioning during ECMO. We collected hemodynamic, respiratory and ventilation variables as follows: pre-treatment, 1, 6, and 24 h post-treatment, and documented treatment-related complications. On-treatment variables were compared with pre-treatment using one-sample paired t-test with Bonferroni correction.

Results

Fourteen patients (mean age 48.1 [SD 9.3] years, male [100%]) received VV-ECMO. Of those, 10 patients had data during prone positioning alone and seven had data while proned on ECMO. While on ECMO, patients had improvement in oxygen saturation, PaO₂/FiO₂ ratio, and minute ventilation up to 24 h post-treatment. Vasopressor requirements increased with ECMO at 1 h and 24 h post-treatment. Prone positioning was not associated with clinically significant hemodynamic or respiratory changes, either alone or during ECMO support. All patients sustained deep tissue injuries, but only those on the face or chest were related to prone positioning. Three patients required cannula replacement. In-hospital mortality was 43%.

Conclusions

VV-ECMO and prone positioning in patients with COVID-19 ARDS was overall well-tolerated; however, physiologic improvements were marginal, and patients sustained deep tissue injuries. Although this was a selected population with high mortality, our data call into question the benefits of these management modalities in this severe COVID-19 population.