PulmonaryExtracorporeal membrane oxygenation (ECMO) as a treatment strategy for severe acute respiratory distress syndrome (ARDS) in the low tidal volume era: A systematic review☆,☆☆,★,★★
Graphical abstract
Introduction
Despite recent advances in the management of acute respiratory distress syndrome (ARDS), including low tidal volume ventilation [1], neuromuscular blockade [2], and prone positioning [3], severe ARDS is still associated with a 46–52% mortality [4], [5].
In light of the favourable results of extracorporeal membrane oxygenation (ECMO) during the most recent H1N1 pandemic, and the randomized control trial by the CESAR collaboration, ECMO's appeal as a potential therapy for patients with severe ARDS has increased [6], [7], [8], [9]. The positive findings from the H1N1 pandemic and CESAR trial contradict those of two previous randomized controlled trials [10], [11], purportedly due to improved ECMO technology and better patient selection [6].
Although previous systematic reviews have examined the benefit of ECMO in ARDS, they included studies in which patients received mechanical ventilation with tidal volumes of up to 10–12 cm3/kg, as well as studies with patients that did not meet the current criteria for severe ARDS [12], [13]. Inclusion of such patients may bias the results of these reviews. Although the direction of the bias remains unclear, it is our hypothesis that the inclusion of studies in which patients received high tidal volumes has led to an overestimate of the benefit of ECMO. As such, to better reflect the impact of ECMO use in current clinical practice, we performed a systematic review of observational studies and randomized controlled trials comparing patients with severe ARDS managed with ECMO and low tidal volume mechanical ventilation to those managed with low tidal volume mechanical ventilation only. We excluded all trials that did not use a low tidal volume ventilation strategy prior to the initiation of ECMO and for patients in the control group. Furthermore, given that much of the resurgence in the use of ECMO technology has been related to its use during the H1N1 epidemic, we performed a subgroup analysis on articles that include only patients with a primary diagnosis of H1N1.
Section snippets
Data sources and searches
Trials and conference abstracts were identified using an electronic search of MEDLINE, PubMed, Cochrane Central Register of Controlled Trials, and EMBASE, including publications in all languages. Reference lists of relevant articles as well as works cited were hand searched by two independent authors (BT, MK). Our search combined Medical Subject Headings and keywords for ECMO and ARDS to identify relevant articles (Fig. S1). Randomized control trials and observational studies with > 10 subjects
Study selection
The search strategy retrieved 1782 citations comprising 1725 unique abstracts. After review, 1602 abstracts were excluded for failure to meet eligibility criteria. Of the 123 identified for full text review 26 met inclusion criteria (Fig. 1). These studies included one randomized control trial [6], 4 matched cohort studies [7], [8], [9], [18], 2 non-matched cohort studies [19], [20], 2 prospective cohort studies without a control group [31], [33], 9 retrospective cohort studies without a
Discussion
As the first systematic review to focus on ECMO patients treated with low tidal volume ventilation, this paper better reflects the use of ECMO in the current clinical environment. The finding of a wide range of survival to hospital discharge is a testament to the current high clinical variability regarding the initiation of ECMO, and undoubtedly reflects local differences in patient selection, implementation strategies, ECMO setup, patient management, and provider comfort.
Interestingly, these
Conclusion
Current data demonstrates that patients with severe ARDS treated with ECMO and low tidal volume ventilation have a survival to hospital discharge ranging from 33.3 to 86%, compared to 36.3–71.2% among patients treated with low tidal volume mechanical ventilation alone. Five studies were identified with appropriate control groups allowing comparison between these therapies and two demonstrated a significant difference in survival to hospital discharge, both favouring ECMO over conventional
Acknowledgements
Lee Bowman – translation services.
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Cited by (15)
SEDAR/SECCE ECMO management consensus document
2021, Cirugia CardiovascularSEDAR/SECCE ECMO management consensus document
2021, Revista Espanola de Anestesiologia y ReanimacionOutcomes of extracorporeal membrane oxygenation in adult patients with hypoxemic respiratory failure refractory to mechanical ventilation
2018, Respiratory Medicine Case ReportsCitation Excerpt :Appropriate patient selection, timing and use of validated treatment options, including prone positioning before initiation of extracorporeal support have been reported to be key factors for treatment success [9]. Systematic reviews and meta-analysis have provided encouraging results in patients with refractory ARDS who receive veno-venous ECMO with survival rates around 60% at hospital discharge despite initial high illness severity [9,10]. However, real-life studies are needed to further assess the optimal use, outcomes, and different aspects of ECMO care.
Acute respiratory failure and mechanical ventilation
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Work performed at London Health Sciences Centre, London Ontario Canada.
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No reprints required.
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No financial support was provided for this project.
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No conflicts of interest.