Long- and short-term clinical impact of awake extracorporeal membrane oxygenation as bridging therapy for lung transplantation

Prognostic factors in lung transplantation after extracorporeal membrane oxygenation bridging therapy: a systematic review and meta-analysis

Background

Extracorporeal membrane oxygenation (ECMO) has recently emerged as a critical support system for lung function in patients awaiting lung transplantation. This meta-analysis investigates the prognostic factors of lung transplantation following ECMO bridging therapy.

Methods

A comprehensive search was conducted in PubMed, Cochrane Library, Embase, CINAHL, Web of Science, Scopus, and ProQuest databases from inception to August 11, 2023. Included were cohort or case-control studies focusing on prognostic factors of lung transplantation with ECMO bridging therapy. Data extraction was performed independently, and study quality was assessed. A meta-analysis was carried out using RevMan 5.4 and Stata17.0 software to aggregate mortality rates and pertinent prognostic factors of ECMO as a bridge to lung transplantation.

Results

The search identified eight trials encompassing 1,086 participants. The prognosis of patients undergoing lung transplantation with ECMO bridging was significantly associated with several factors: prolonged ECMO support [odds ratio 1.07, 95% confidence interval (CI): 1.02-1.12, I2=77%], deterioration in liver and kidney function (odds ratio 3.62, 95% CI: 2.37-5.54, I2=0%), and complications during ECMO (odds ratio 2.24, 95% CI: 1.45-3.44, I2=5%).

Conclusions

Prolonged ECMO support, declining liver and kidney functions, and complications during ECMO are vital prognostic factors in lung transplantation following ECMO bridging therapy.

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

BACKGROUND

Patients with severe respiratory failure due to COVID-19 who are not under mechanical ventilation may develop severe hypoxemia when complicated with spontaneous pneumomediastinum (PM). These patients may be harmed by invasive ventilation. Alternatively, veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) may be applied. We report on the efficacy of V-V ECMO and invasive ventilation as initial advanced respiratory support in patients with COVID-19 and acute respiratory failure due to spontaneous PM.

METHODS

This was a retrospective cohort study performed between March 2020 and January 2022. Enrolled patients had COVID-19 and acute respiratory failure due to spontaneous PM and were not invasively ventilated. Patients were treated in the intensive care unit (ICU) with invasive ventilation (invasive ventilation group) or V-V ECMO support (V-V ECMO group) as the main therapeutic option. The primary outcomes were mortality and ICU discharge at 90 days after ICU admission.

RESULTS

Twenty-two patients were included in this study (invasive ventilation group: 13 [59%]; V-V ECMO group: 9 [41%]). The V-V ECMO strategy was significantly associated with lower mortality (hazard ratio [HR] 0.33 [95% CI 0.12-0.97], p = 0.04). Five (38%) patients in the V-V ECMO group were intubated and eight (89%) patients in the invasive ventilation group required V-V ECMO support within 30 days from ICU admission. Three (33%) patients in the V-V ECMO group were discharged from ICU within 90 days compared to one (8%) patient in the invasive ventilation group (HR 4.71 [95% CI 0.48-45.3], p = 0.18).

CONCLUSIONS

Preliminary data suggest that V-V ECMO without invasive ventilation may improve survival in COVID-19-related acute respiratory failure due to spontaneous PM. The study's retrospective design and limited sample size underscore the necessity for additional investigation and warrant caution.

Which strategy is better for lung transplantation: Cardiopulmonary bypass or extracorporeal membrane oxygenation?

Background: In lung transplantation surgery, extracorporeal life support (ECLS) is essential for safety. Various support methods, including cardiopulmonary bypass (CPB) and off-pump techniques, are used, with extracorporeal membrane oxygenation (ECMO) gaining prominence. However, consensus on the best support strategy is lacking.Purpose: This article reviews risks, benefits, and outcomes of different support strategies in lung transplantation. By consolidating knowledge, it aims to clarify selecting the most appropriate ECLS modality.Research Design: A comprehensive literature review examined CPB, off-pump techniques, and ECMO outcomes in lung transplantation, including surgical results and complications.Study Sample: Studies, including clinical trials and observational research, focused on ECLS in lung transplantation, both retrospective and prospective, providing a broad evidence base.Data Collection and/or Analysis: Selected studies were analyzed for surgical outcomes, complications, and survival rates associated with CPB, off-pump techniques, and ECMO to assess safety and effectiveness.Results: Off-pump techniques are preferred, with ECMO increasingly vital as a bridge to transplant, overshadowing CPB. However, ECMO entails hidden risks and higher costs. While safer than CPB, optimizing ECMO postoperative use and monitoring is crucial for success.Conclusions: Off-pump techniques are standard, but ECMO's role is expanding. Despite advantages, careful ECMO management is crucial due to hidden risks and costs. Future research should focus on refining ECMO use and monitoring to improve outcomes, emphasizing individualized approaches for LT recipients.

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

OBJECTIVES

Dual-lumen cannulas for veno-venous (VV) extracorporeal membrane oxygenation (ECMO) support are typically inserted in the right internal jugular vein (RIJV); however, some scenarios can make this venous route inaccessible. This multicentre case series aims to evaluate if single-site cannulation using an alternative venous access is safe and feasible in patients with an inaccessible RIJV.

METHODS

We performed a multi-institutional retrospective analysis including high-volume ECMO centres with substantial experience in dual-lumen cannulation (DLC) (defined as >10 DLC per year). Three centres [Freiburg (Germany), Toronto (Canada) and Vienna (Austria)] agreed to share their data, including baseline characteristics, technical ECMO and cannulation data as well as complications related to ECMO cannulation and outcome.

RESULTS

A total of 20 patients received alternative DLC for respiratory failure. Cannula insertion sites included the left internal jugular vein (n = 5), the right (n = 7) or left (n = 3) subclavian vein and the right (n = 4) or left (n = 1) femoral vein. The median cannula size was 26 (19-28) French. The median initial target ECMO flow was 2.9 (1.8-3.1) l/min and corresponded with used cannula size and estimated cardiac output. No procedural complications were reported during cannulation and median ECMO runtime was 15 (9-22) days. Ten patients were successfully bridged to lung transplantation (n = 5) or lung recovery (n = 5). Ten patients died during or after ECMO support.

CONCLUSIONS

Alternative venous access sites for single-site dual-lumen catheters are a safe and feasible option to provide veno-venous ECMO support to patients with inaccessible RIJV.

Extracorporeal membrane oxygenation as a bridge to lung transplantation: Practice patterns and patient outcomes

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly relied on to bridge patients with respiratory failure to lung transplantation despite limited evidence for its use in this setting. This study evaluated longitudinal trends in practice patterns, patient characteristics, and outcomes in patients bridged with ECMO to lung transplant.

METHODS

A retrospective review of all adult isolated lung transplant patients in the United Network for Organ Sharing database between 2000 and 2019 was performed. Patients were classified as "ECMO" if supported with ECMO at the time of listing or transplantation and "non-ECMO" otherwise. Linear regression was used to evaluate trends in patient demographics during the study period. Trends in mortality were evaluated using Cox proportional hazards modeling, with time period as the primary covariate (2000-2004, 2005-2009, 2010-2014, or 2015-2019) and age, time on the waitlist, and underlying diagnosis as covariates.

RESULTS

The number of patients included were 40,866, of whom 1,387 (3.4%) were classified as ECMO and 39,479 (96.6%) as no ECMO. Average age and initial Lung Allocation Score increased significantly during the study period in both cohorts, but occurred at a slower rate in the ECMO population. The hazard of death was significantly lower in more recent years (2015-2019) for both the ECMO and non-ECMO cohorts (aHR (adjusted hazards ratio) 0.59, 95% confidence interval (CI) 0.37-0.96 and aHR 0.74, 95% CI 0.70-0.79) when compared to the early years (2000-2004) of the study period.

CONCLUSIONS

Post-transplantation survival for patients bridged to transplantation with ECMO demonstrates ongoing improvement despite cannulation of progressively older and sicker patients.

Extracorporeal Membrane Oxygenation Without Invasive Ventilation for Respiratory Failure in Adults: A Systematic Review

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) is an advanced treatment for acute severe respiratory failure. Patients on ECMO are frequently maintained sedated and immobilized until weaning from ECMO, first, and then from mechanical ventilation. Avoidance of sedation and invasive ventilation during ECMO may have potential advantages. We performed a systematic literature review to assess efficacy and safety of awake ECMO without invasive ventilation in patients with respiratory failure.

DATA SOURCES

PubMed, Web of Science, and Scopus were searched for studies reporting outcome of awake ECMO for adult patients with respiratory failure.

STUDY SELECTION

We included all studies reporting outcome of awake ECMO in patients with respiratory failure. Studies on ECMO for cardiovascular failure, cardiac arrest, or perioperative support and studies on pediatric patients were excluded. Two investigators independently screened and selected studies for inclusion.

DATA EXTRACTION

Two investigators abstracted data on study characteristics, rate of awake ECMO failure, and mortality. Primary outcome was rate of awake ECMO failure (need for intubation). Pooled estimates with corresponding 95% CIs were calculated. Subgroup analyses by setting were performed.

DATA SYNTHESIS

A total of 57 studies (28 case reports) included data from 467 awake ECMO patients. The subgroup of patients with acute respiratory distress syndrome showed a pooled estimate for awake ECMO failure of 39.3% (95% CI, 24.0-54.7%), while in patients bridged to lung transplantation, pooled estimate was 23.4% (95% CI, 13.3-33.5%). Longest follow-up mortality was 121 of 439 (pooled estimate, 28%; 95% CI, 22.3-33.6%). Mortality in patients who failed awake ECMO strategy was 43 of 74 (pooled estimate, 57.2%; 95% CI, 40.2-74.3%). Two cases of cannula self-removal were reported.

CONCLUSIONS

Awake ECMO is feasible in selected patients, although the effect on outcome remains to be demonstrated. Mortality is almost 60% in patients who failed awake ECMO strategy.

Extracorporeal life support as a bridge to lung transplantation: a narrative review

Background and Objective

The utilization of extracorporeal life support (ECLS) as a bridge to lung transplantation (LTx) has rapidly expanded over recent years in highly urgent patients even though the reported outcomes in current literature are still divergent. The aim of our narrative review was to provide a comprehensive picture on the peri and post-operative outcomes of patients bridged to LTx with this device from the most updated literature in the field.

Methods

The literature about ECLS bridge to LTx was searched on PubMed using a formal strategy. We focused our research on studies published between 2015 and 2022 and in English language. Abstracts, case reports, conference presentations, editorials, expert opinions and review articles were excluded.

Key Content and Findings

ECLS has emerged as a valid tool to bridge critically ill patients to LTx. Some issues, like the selection of candidates and the post-operative outcomes, are still matter of debate in the current reported series. We analyzed 14 papers published in the last seven years and with at least 20 patients to provide an updated overview on this topic. We found that, in highly experienced centers, ECLS can be used as a good strategy to allow critically ill patients to remain eligible to LTx with satisfying post-operative outcomes.

Conclusions

Specific scores and algorithms should be implemented to improve the selection process of candidates who could benefit more from ECLS as a bridge to LTx. Ambulatory/awake ECLS strategies should be always preferred to enroll patients in active rehabilitation programs awaiting LTx, improving short and long-term outcomes and increasing the success of LTx.

Awakening in extracorporeal membrane oxygenation as a bridge to lung transplantation

Although the rate of lung transplantation (LTx), the last treatment option for end-stage lung disease, is increasing, some patients waiting for LTx need a bridging strategy for LTx due to the limited number of available donor lungs. For a long time, mechanical ventilation has been employed as a bridge to LTx because the outcome of using extracorporeal membrane oxygenation (ECMO) as a bridging strategy has been poor. However, the outcome after mechanical ventilation as a bridge to LTx was poor compared with that in patients without bridges. With advances in technology and the accumulation of experience, the outcome of ECMO as a bridge to LTx has improved, and the rate of ECMO use as a bridging strategy has increased over time. However, whether the use of ECMO as a bridge to LTx can achieve survival rates similar to those of non-bridged LTx patients remains controversial. In 2010, one center introduced awake ECMO strategy for LTx bridging, and its use as a bridge to LTx has been showing favorable outcomes to date. Awake ECMO has several advantages, such as maintenance of physical activity, spontaneous breathing, avoidance of endotracheal intubation, and reduced use of sedatives and analgesics, but it may cause serious problems. Nonetheless, several studies have shown that awake ECMO performed by a multidisciplinary team is safe. In cases where ECMO or mechanical ventilation is required due to unavoidable exacerbation in patients awaiting LTx, the application of awake ECMO performed by an appropriately trained ECMO multi-disciplinary team can be useful.