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

Awake Venovenous Extracorporeal Membrane Oxygenation in the Intensive Care Unit: Challenges and Emerging Concepts

Extracorporeal membrane oxygenation (ECMO) is an advanced treatment for severe respiratory failure. Implantation of ECMO before invasive ventilation or extubation during ECMO has been reported and is becoming increasingly popular. Avoidance of sedation and invasive ventilation during ECMO (commonly referred to as "awake ECMO") may have potential advantages, including a lower rate of delirium, shorter mechanical ventilation time, and the possibility of undergoing early rehabilitation and/or physiotherapy. However, awake ECMO is also associated with several risks, such as self-inflicted lung injury and cannula displacement or self-removal. Accordingly, invasive ventilation before ECMO, as well as weaning from ECMO before weaning from mechanical ventilation, remain the most common approaches. In this review, the authors describe indications, contraindications, advantages, disadvantages, and current evidence on the use of ECMO without invasive ventilation in patients with respiratory failure.

Sedation management and processed EEG-based solutions during venovenous extracorporeal membrane oxygenation: a narrative review of key challenges and potential benefits

Extracorporeal membrane oxygenation (ECMO) is an established technique for managing severe cardiorespiratory failure. However, it is invasive and requires profound analgo-sedation during initiation and often throughout the therapy. Managing sedation in venovenous (VV) ECMO patients is particularly challenging due to the impact of ECMO circuits on pharmacokinetics and specific patient requirements. This can lead to unpredictable sedative effects and require multiple drugs at higher doses. Additionally, sedation is usually managed with traditional scoring methods, which are subjective and invalid during neuromuscular blockade. These uncertainties may impact outcomes. Recent clinical practice increasingly focuses on reducing sedation to enable earlier physiotherapy and mobilisation, particularly in patients awaiting transplants or receiving mechanical circulatory support. In this context, processed electroencephalogram-based (pEEG) sedation monitoring might be promising, having shown benefits in general anaesthesia and intensive care. However, the technology has limitations, and its benefits in ECMO practice have yet to be formally evaluated. This review provides insights into the challenges of ECMO sedation, including pharmacokinetics, unique ECMO requirements, and the implications of inadequate sedation scores. Finally, it includes a brief overview of the practicality and limitations of pEEG monitoring during VV-ECMO, highlighting a significant research gap.

Patient-Self Inflicted Lung Injury (P-SILI): An Insight into the Pathophysiology of Lung Injury and Management

Acute respiratory distress syndrome (ARDS) is a heterogeneous group of disease entities that are associated with acute hypoxic respiratory failure and significant morbidity and mortality. With a better understanding and phenotyping of lung injury, novel pathophysiologic mechanisms demonstrate the impact of a patient's excessive spontaneous breathing effort on perpetuating lung injury. Patient self-inflicted lung injury (P-SILI) is a recently identified phenomenon that delves into the impact of spontaneous breathing on respiratory mechanics in patients with lung injury. While the studies are hypothesis-generating and have been demonstrated in animal and human studies, further clinical trials are needed to identify its impact on ARDS management. The purpose of this review article is to highlight the physiologic mechanisms of P-SILI, novel tools and methods to detect P-SILI, and to review the current literature on non-invasive and invasive respiratory management in patients with ARDS.

Weakness acquired in the cardiac intensive care unit: still the elephant in the room?

Over the past two decades, the cardiac critical care population has shifted to increasingly comorbid and elderly patients often presenting with nonprimary cardiac conditions that exacerbate underlying advanced cardiac disease. Consequently, the modern cardiac intensive care unit (CICU) patient has poor outcome regardless of left ventricular ejection fraction. Importantly, delayed liberation from organ support, independent from premorbid health status and admission severity of illness, has been associated with increased morbidity and mortality up to years post-general critical care. Although a constellation of several acquired morbidities is at play, the most prominent enactor of poor long-term outcome in this population appears to be intensive care unit acquired weakness. Although the specific burden of ICU-acquired morbidities in CICU patients is yet to be clearly defined, it seems unfathomable that patients will not accrue some sort of ICU-related morbidity. There is hence an urgent need to better establish the exact benefit and cost of resource-intensive strategies in both short- and long-term survival of the CICU patient. Consequent and standardized documentation of admission comorbidities, severity of illness indicators, relevant ICU-related complications including weakness, and long-term post-ICU morbidity outcomes can help our understanding of the disease continuum and how to better care for the CICU survivor and their families and caregivers. Given increasing budgetary pressure on healthcare systems worldwide, interventions targeting CICU patients should focus on improving patient-centred long-term outcomes in a cost-effective manner. It will require a holistic and transmural continuity of care model to meet the challenges associated with treating critically ill cardiac patients in the future.

Extracorporeal membrane oxygenation for prevention of barotrauma in patients with respiratory failure: A scoping review

BACKGROUND

Barotrauma is a frequent complication in patients with severe respiratory failure and is associated with poor outcomes. Extracorporeal membrane oxygenation (ECMO) implantation allows to introduce lung-protective ventilation strategies that limit barotrauma development or progression, but available data are scarce. We performed a scoping review to summarize current knowledge on this therapeutic approach.

METHODS

We systematically searched PubMed/MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials for studies investigating ECMO as a strategy to prevent/limit barotrauma progression in patients with respiratory failure. Pediatric studies, studies on perioperative implantation of ECMO, and studies not reporting original data were excluded. The primary outcome was the rate of barotrauma development/progression.

RESULTS

We identified 21 manuscripts presenting data on a total of 45 ECMO patients. All patients underwent veno-venous ECMO. Of these, 21 (46.7%) received ECMO before invasive mechanical ventilation. In most cases, ECMO implantation allowed to modify the respiratory support strategy (e.g., introduction of ultraprotective/low pressure ventilation in 12 patients, extubation while on ECMO in one case, and avoidance of invasive ventilation in 15 cases). Barotrauma development/progression occurred in <10% of patients. Overall mortality was 8/45 (17.8%).

CONCLUSION

ECMO implantation to prevent barotrauma development/progression is a feasible strategy and may be a promising support option.

Awake veno-venous extracorporeal membrane oxygenation: practical aspects and considerations

Veno-venous extracorporeal membrane oxygenation (ECMO) is a life-saving technique in the armamentarium of critical care medicine. It involves extracorporeal blood circulation outside the body, providing temporary respiratory support while allowing the lungs to heal. Traditionally, patients undergoing ECMO require sedation to minimize discomfort and facilitate mechanical ventilation. The "awake ECMO" concept emerged as a promising strategy to mitigate sedation-related complications and facilitate early mobilization in critically ill patients. In this article, we describe the potential advantages of awake ECMO and its role in preserving respiratory muscle function, enhancing rehabilitation prospects, and improving patient outcomes.

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.

Macklin Effect: From Pathophysiology to Clinical Implication

Air leak syndromes (such as pneumomediastinum, pneumothorax, or subcutaneous emphysema) are frequent complications of acute respiratory distress syndrome (ARDS). Unfortunately, the development of air leaks is associated with worse outcomes. In addition, it has been hypothesized that the development of pneumomediastinum could be a marker of disease severity in patients with respiratory failure receiving noninvasive respiratory support or assisted ventilation. The so-called Macklin effect (or pulmonary interstitial emphysema) is the air dissection of the lung bronchovascular tree from peripheral to central airways following injury to distal alveoli. Ultimately, the progression of the Macklin effect leads to the development of pneumomediastinum, subcutaneous emphysema, or pneumothorax. The Macklin effect is identifiable on a chest computed tomography (CT) scan. The Macklin effect could be an accurate predictor of barotrauma in patients with ARDS (sensitivity = 89.2% [95% CI: 74.6-96.9]; specificity = 95.6% [95% CI: 90.6-98.4]), and may be a marker of disease severity. Accordingly, the detection of the Macklin effect on a chest CT scan could be used to select which patients with ARDS might benefit from different treatment algorithms, including advanced respiratory monitoring, early intubation, or, potentially, the institution of early extracorporeal support with or without invasive ventilation. In this video, the authors summarize the pathophysiology and potential clinical significance and applications of the Macklin effect in patients with acute respiratory failure.

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.