Spontaneous breathing during veno-venous extracorporeal membrane oxygenation

Optimizing the safety and efficacy of the awake venovenous extracorporeal membrane oxygenation in patients with COVID-19-related ARDS

BACKGROUND

Maintaining the patient awake and not intubated during the venovenous extracorporeal membrane oxygenation (VV ECMO) reduces the risk of ventilation-induced lung injury in patients with ARDS. Currently, there is a lack of data on outcomes and complications associated with the awake ECMO approach.

OBJECTIVES

To evaluate outcomes and the occurrence of complications of awake ECMO approach guided by local safety protocol comprising ultrasound-guided cannulation, argatroban-based anticoagulation, respiratory support, and routine sedation targeted to reduce respiratory effort and keeping nurse-to-patient ratio of 1:1.

DESIGN

A single-center retrospective case series analysis.

METHODS

Consecutive patients with COVID-19-related acute respiratory distress syndrome (ARDS) (CARDS) treated by full awake VV ECMO approach from April 2019 to December 2023 were eligible.

RESULTS

Our center treated 10 patients (mean age 54.7 ± 11.6 years) with CARDS with an awake ECMO approach. The reasons for awake ECMO included the presence of barotrauma in six patients, a team consensus to prefer awake ECMO instead of mechanical ventilation in three patients, and the patient's refusal to be intubated in one case. Before ECMO, patients were severely hypoxemic, with a mean value of Horowitz index of 48.9 ± 9.1 mmHg and a mean respiratory rate of 28.8 ± 7.3 breaths per minute on high-flow nasal cannula or noninvasive ventilation support. The mean duration of awake VV ECMO was 558.0 ± 173.6 h. Seven patients (70%) were successfully disconnected from ECMO and fully recovered. Intubation from respiratory causes was needed in three patients (30%), all of whom died eventually. In total, three episodes of delirium, two episodes of significant bleeding, one pneumothorax requiring chest tube insertion, and one oxygenator acute exchange occurred throughout the 5580 h of awake ECMO. No complications related to cannula displacement or malposition occurred.

CONCLUSION

The awake ECMO strategy guided by safety protocol appears to be a safe approach in conscious, severely hypoxemic, non-intubated patients with COVID-19-related ARDS.

Current knowledge gaps in extracorporeal respiratory support

Extracorporeal life support (ECLS) for acute respiratory failure encompasses veno-venous extracorporeal membrane oxygenation (V-V ECMO) and extracorporeal carbon dioxide removal (ECCO2R). V-V ECMO is primarily used to treat severe acute respiratory distress syndrome (ARDS), characterized by life-threatening hypoxemia or ventilatory insufficiency with conventional protective settings. It employs an artificial lung with high blood flows, and allows improvement in gas exchange, correction of hypoxemia, and reduction of the workload on the native lung. On the other hand, ECCO2R focuses on carbon dioxide removal and ventilatory load reduction ("ultra-protective ventilation") in moderate ARDS, or in avoiding pump failure in acute exacerbated chronic obstructive pulmonary disease. Clinical indications for V-V ECLS are tailored to individual patients, as there are no absolute contraindications. However, determining the ideal timing for initiating extracorporeal respiratory support remains uncertain. Current ECLS equipment faces issues like size and durability. Innovations include intravascular lung assist devices (ILADs) and pumpless devices, though they come with their own challenges. Efficient gas exchange relies on modern oxygenators using hollow fiber designs, but research is exploring microfluidic technology to improve oxygenator size, thrombogenicity, and blood flow capacity. Coagulation management during V-V ECLS is crucial due to common bleeding and thrombosis complications; indeed, anticoagulation strategies and monitoring systems require improvement, while surface coatings and new materials show promise. Moreover, pharmacokinetics during ECLS significantly impact antibiotic therapy, necessitating therapeutic drug monitoring for precise dosing. Managing native lung ventilation during V-V ECMO remains complex, requiring a careful balance between benefits and potential risks for spontaneously breathing patients. Moreover, weaning from V-V ECMO is recognized as an area of relevant uncertainty, requiring further research. In the last decade, the concept of Extracorporeal Organ Support (ECOS) for patients with multiple organ dysfunction has emerged, combining ECLS with other organ support therapies to provide a more holistic approach for critically ill patients. In this review, we aim at providing an in-depth overview of V-V ECMO and ECCO2R, addressing various aspects of their use, challenges, and potential future directions in research and development.

Standardized approach for extubation during extracorporeal membrane oxygenation in severe acute respiratory distress syndrome: a prospective observational study

BACKGROUND

Extubation during extracorporeal oxygenation (ECMO) in severe acute respiratory distress syndrome (ARDS) has not been well studied. Despite the potential benefits of this strategy, weaning from ECMO before liberation from invasive mechanical ventilation remains the most frequent approach. Our aim was to evaluate the safety and feasibility of a standardized approach for extubation during ECMO in patients with severe ARDS.

RESULTS

We conducted a prospective observational study to assess the safety and feasibility of a standardized approach for extubation during ECMO in severe ARDS among 254 adult patients across 4 intensive care units (ICU) from 2 tertiary ECMO centers over 6 years. This consisted of a daily assessment of clinical and gas exchange criteria based on an Extracorporeal Life Support Organization guideline, with extubation during ECMO after validation by a dedicated intensive care medicine specialist. Fifty-four (21%) patients were extubated during ECMO, 167 (66%) did not reach the clinical criteria, and in 33 (13%) patients, gas exchange precluded extubation during ECMO. At ECMO initiation, there were fewer extrapulmonary organ dysfunctions (lower SOFA score [OR, 0.88; 95% CI, 0.79-0.98; P = .02] with similar PaO2/FiO2) when compared with patients not extubated during ECMO. Extubation during ECMO associated with shorter duration of invasive mechanical ventilation (7 (4-18) vs. 32 (18-54) days; P < .01) and of ECMO (12 (7-25) vs. 19 (10-41) days; P = .01). This was accompanied by a lower incidence of hemorrhagic shock (2 vs. 11%; P = .05), but more cannula-associated deep vein thrombosis (49 vs. 31%; P = .02) and failed extubation (20 vs. 6%; P < .01). There were no increased major adverse events. Extubation during ECMO is associated with a lower risk of all-cause death, independently of measured confounding (adjusted logistic regression OR 0.23; 95% confidence interval 0.08-0.69, P = .008).

CONCLUSIONS

A standardized approach was safe and feasible allowing extubation during ECMO in 21% of patients with severe ARDS, selecting patients who will have a shorter duration of invasive mechanical ventilation, ECMO course, and ICU stay, as well as fewer infectious complications, and high hospital survival.

Extracorporeal membrane oxygenation in immunocompromised patients with acute respiratory failure: A retrospective cohort study

BACKGROUND

The clinical indications of extracorporeal membrane oxygenation (ECMO) in immunosuppressed patients are not clear. This study aimed to analyse the effectiveness of ECMO and to identify the risk factors for the mortality of ECMO in immunocompromised patients with acute respiratory failure.

METHODS

This retrospective, cohort study included 46 confirmed immunocompromised patients with acute hypoxemic respiratory failure treated with ECMO between July 2014 and August 2020. The clinical features and outcomes of the survival group and the non-survival group were statistically analysed.

RESULTS

The mean age of the enrolled patients was 60.0 (50.0, 66.0) years; male patients accounted for 60.9% of patients, and the mean CD4 level was 213 cells/μL (150.3, 325.3). The hospital mortality rate of the cohort was 67.4% (31/46 patients). Patients in the survival group showed a higher rate of receiving awake ECMO (11/15 vs. 4/31; p = 0.006), a lower rate of acute kidney injury (AKI) receiving continuous renal replacement therapy (CRRT) (1/15 vs. 12/31; p = 0.035), fewer platelet transfusion units (0/15 vs. 2/31 units; p = 0.039) and a lower rate of ventilator-associated pneumonia (2/15 vs. 19/31; p = 0.006). In a multivariate Cox regression analysis model, intubated ECMO (hazard ratio = 1.77, 95% confidence interval: 1.34-2.32, p < 0.001) and AKI requiring CRRT (1.37, 95% confidence interval: 1.14-1.61, p = 0.003) were identified as independent risk factors for mortality.

CONCLUSIONS

In-hospital mortality has remained high in ECMO-treated immunocompromised patients with acute respiratory failure. Intubated ECMO and AKI receiving CRRT during ECMO treatment may predict ECMO failure in immunocompromised patients with ARF. A primarily awake ECMO strategy seems feasible in some selected immunocompromised patients.

Extracorporal Membrane Oxygenation in Nonintubated Patients (Awake ECMO) With COVID-19 Adult Respiratory Distress Syndrome: The Israeli Experience

In this retrospective multicenter observational study, we describe the Israeli experience with veno-venous extracorporeal membrane oxygenation (VV ECMO) for the treatment of COVID-19-induced severe adult respiratory distress syndrome (ARDS), in which ECMO cannulation was done while the patients were awake and spontaneously breathing without endotracheal tube, namely "awake ECMO." We enrolled all adult patients with severe ARDS due to COVID-19, treated with VV ECMO between March 1, 2020, and November 30, 2021, in which cannulation was done while the patient was awake and spontaneously breathing. During the study period, 365 COVID-19 ARDS patients were treated with VV ECMO. Of these, 25 (6.8%) were treated as awake ECMO. The patient's mean age was 52 years, and 80% were male. Nine of the 25 patients (36%) remained awake throughout their intensive care unit stay and were not sedated and mechanically ventilated at all. Sixteen (64%) were eventually intubated while being on ECMO. Six months survival was 76%. Median mechanical ventilation-free days on ECMO was 8 (interquartile range 5-12) days. This hypothesis-generating study suggests that treating COVID-19 ARDS patients with VV ECMO without sedation and mechanical ventilation is feasible, yet, additional research will be required in order to determine if this modality offers a survival benefit and to identify who are the patients most likely to benefit from it.

Patient Self-Inflicted Lung Injury-A Narrative Review of Pathophysiology, Early Recognition, and Management Options

Patient self-inflicted lung injury (P-SILI) is a life-threatening condition arising from excessive respiratory effort and work of breathing in patients with lung injury. The pathophysiology of P-SILI involves factors related to the underlying lung pathology and vigorous respiratory effort. P-SILI might develop both during spontaneous breathing and mechanical ventilation with preserved spontaneous respiratory activity. In spontaneously breathing patients, clinical signs of increased work of breathing and scales developed for early detection of potentially harmful effort might help clinicians prevent unnecessary intubation, while, on the contrary, identifying patients who would benefit from early intubation. In mechanically ventilated patients, several simple non-invasive methods for assessing the inspiratory effort exerted by the respiratory muscles were correlated with respiratory muscle pressure. In patients with signs of injurious respiratory effort, therapy aimed to minimize this problem has been demonstrated to prevent aggravation of lung injury and, therefore, improve the outcome of such patients. In this narrative review, we accumulated the current information on pathophysiology and early detection of vigorous respiratory effort. In addition, we proposed a simple algorithm for prevention and treatment of P-SILI that is easily applicable in clinical practice.

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 .

Extracorporeal membrane oxygenation in adults receiving haematopoietic cell transplantation: an international expert statement

Combined advances in haematopoietic cell transplantation (HCT) and intensive care management have improved the survival of patients with haematological malignancies admitted to the intensive care unit. In cases of refractory respiratory failure or refractory cardiac failure, these advances have led to a renewed interest in advanced life support therapies, such as extracorporeal membrane oxygenation (ECMO), previously considered inappropriate for these patients due to their poor prognosis. Given the scarcity of evidence-based guidelines on the use of ECMO in patients receiving HCT and the need to provide equitable and sustainable access to ECMO, the European Society of Intensive Care Medicine, the Extracorporeal Life Support Organization, and the International ECMO Network aimed to develop an expert consensus statement on the use of ECMO in adult patients receiving HCT. A steering committee with expertise in ECMO and HCT searched the literature for relevant articles on ECMO, HCT, and immune effector cell therapy, and developed opinion statements through discussions following a Quaker-based consensus approach. An international panel of experts was convened to vote on these expert opinion statements following the Research and Development/University of California, Los Angeles Appropriateness Method. The Appraisal of Guidelines for Research and Evaluation statement was followed to prepare this Position Paper. 36 statements were drafted by the steering committee, 33 of which reached strong agreement after the first voting round. The remaining three statements were discussed by all members of the steering committee and expert panel, and rephrased before an additional round of voting. At the conclusion of the process, 33 statements received strong agreement and three weak agreement. This Position Paper could help to guide intensivists and haematologists during the difficult decision-making process regarding ECMO candidacy in adult patients receiving HCT. The statements could also serve as a basis for future research focused on ECMO selection criteria and bedside management.

Liberation From Mechanical Ventilation Before Decannulation From Venovenous Extracorporeal Life Support in Severe COVID-19 Acute Respiratory Distress Syndrome

The coronavirus disease 2019 (COVID-19) pandemic has been associated with the significant use of venovenous extracorporeal membrane oxygenation (VVECMO) globally. Identifying strategies to optimize care is essential to improving patient important outcomes. By liberation from mechanical ventilation (MV) before VVECMO to provide awake-ECMO, complications related to MV could be minimized, leading to improved outcomes. Between March 2020 and October 2021, we conducted a prospective observational study at the Kuwait Extracorporeal Life Support Program, of patients admitted for COVID-19 acute respiratory distress syndrome (ARDS), with recording baseline characteristics, respiratory support, and ECMO parameters. Of the 207 patients who underwent VVECMO for COVID-19 ARDS during this period, only 5 patients were successfully liberated from MV before decannulation to provide awake-ECMO. Four were female with a median age of 38. Before VVECMO, all patients received corticosteroids and lung-protective ventilation with four receiving prone positioning. The median duration of MV use was 4 days, whereas the median duration of VVECMO use was 12 days, with early mobility, and all survived until hospital discharge. The safety and feasibility of liberation from MV before ECMO decannulation to provide awake-ECMO were demonstrated, but further studies are warranted to identify factors associated with this success.

Outcomes of Extracorporeal Membrane Oxygenation (ECMO) for COVID-19 Patients: A Multi-Institutional Analysis

BACKGROUND

In March 2020, COVID-19 was announced as a global pandemic. The first COVID-19 patient was connected to an ECMO device in Israel during that time. Since then, over 200 patients have required ECMO support due to COVID-19 infection. The present study is a multi-institutional analysis of all COVID-19 patients requiring veno-venous (VV) ECMO in Israel. The aim was to characterize and compare the survivors and deceased patients as well as establish risk factors for mortality.

METHODS

This retrospective multi-institutional study was conducted from March 2020 to March 2021 in eleven of twelve ECMO centers operating in Israel. All COVID-19 patients on VV ECMO support were included in the cohort. The patients were analyzed based on their comorbidities, procedural data, adverse event on ECMO, and outcomes. Univariate and multivariate analyses were used to compare the deceased and the surviving patients.

RESULTS

The study included 197 patients, of which 150 (76%) were males, and the mean age was 50.7 ± 12 years. Overall mortality was 106 (54%). Compared with the deceased subjects, survivors were significantly younger (48 ± 11 vs. 53 ± 12 years), suffered less from ischemic heart disease (IHD) (3% vs. 12%), and were ventilated for a significantly shorter period (≤4 days) prior to cannulation (77% vs. 63%). Patients in the deceased group experienced more kidney failure and sepsis. Rates of other complications were comparable between groups.

CONCLUSIONS

Based on this study, we conclude that early cannulation (≤4 days) of younger patients (≤55 years) may improve overall survival and that a history of IHD might indicate a reduced prognosis.

Strategies for lung- and diaphragm-protective ventilation in acute hypoxemic respiratory failure: a physiological trial

BACKGROUND

Insufficient or excessive respiratory effort during acute hypoxemic respiratory failure (AHRF) increases the risk of lung and diaphragm injury. We sought to establish whether respiratory effort can be optimized to achieve lung- and diaphragm-protective (LDP) targets (esophageal pressure swing - 3 to - 8 cm H2O; dynamic transpulmonary driving pressure ≤ 15 cm H2O) during AHRF.

METHODS

In patients with early AHRF, spontaneous breathing was initiated as soon as passive ventilation was not deemed mandatory. Inspiratory pressure, sedation, positive end-expiratory pressure (PEEP), and sweep gas flow (in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO)) were systematically titrated to achieve LDP targets. Additionally, partial neuromuscular blockade (pNMBA) was administered in patients with refractory excessive respiratory effort.

RESULTS

Of 30 patients enrolled, most had severe AHRF; 16 required VV-ECMO. Respiratory effort was absent in all at enrolment. After initiating spontaneous breathing, most exhibited high respiratory effort and only 6/30 met LDP targets. After titrating ventilation, sedation, and sweep gas flow, LDP targets were achieved in 20/30. LDP targets were more likely to be achieved in patients on VV-ECMO (median OR 10, 95% CrI 2, 81) and at the PEEP level associated with improved dynamic compliance (median OR 33, 95% CrI 5, 898). Administration of pNMBA to patients with refractory excessive effort was well-tolerated and effectively achieved LDP targets.

CONCLUSION

Respiratory effort is frequently absent  under deep sedation but becomes excessive when spontaneous breathing is permitted in patients with moderate or severe AHRF. Systematically titrating ventilation and sedation can optimize respiratory effort for lung and diaphragm protection in most patients. VV-ECMO can greatly facilitate the delivery of a LDP strategy.

TRIAL REGISTRATION

This trial was registered in Clinicaltrials.gov in August 2018 (NCT03612583).

Awake extracorporeal life support and physiotherapy in adult patients: A systematic review of the literature

OBJECTIVE

The Awake Extracorporeal Life Support (ECLS) practice combined with physiotherapy is increasing. However, available evidence for this approach is limited, with unclear indications on timing, management, and protocols. This review summarizes available literature regarding Awake ECLS and physiotherapy application rates, practices, and outcomes in adults, providing indications for future investigations.

METHODS

Four databases were screened from inception to February 2021, for studies reporting adult Awake ECLS with/without physiotherapy. Primary outcome was hospital discharge survival, followed by Extracorporeal Membrane Oxygenation (ECMO) duration, extubation, Intensive Care Unit stay.

RESULTS

Twenty-nine observational studies and one randomized study were selected, including 1,157 patients (males n = 611/691, 88.4%) undergoing Awake ECLS. Support type was reported in 1,089 patients: Veno-Arterial ECMO (V-A = 39.6%), Veno-Venous ECMO (V-V = 56.8%), other ECLS (3.6%). Exclusive upper body cannulation and femoral cannulation were applied in 31% versus 69% reported cases (n = 931). Extubation was successful in 63.5% (n = 522/822) patients during ECLS. Physiotherapy details were given for 676 patients: exercises confined in bed for 47.9% (n = 324) patients, mobilization until standing in 9.3% (n = 63) cases, ambulation performed in 42.7% (n = 289) patients. Femoral cannulation, extubation and V-A ECMO were mostly correlated to complications. Hospital discharge survival observed in 70.8% (n = 789/1114).

CONCLUSION

Awake ECLS strategy associated with physiotherapy is performed regardless of cannulation approach. Ambulation, as main objective, is achieved in almost half the population examined. Prospective studies are needed to evaluate safety and efficacy of physiotherapy during Awake ECLS, and suitable patient selection. Guidelines are required to identify appropriate assessment/evaluation tools for Awake ECLS patients monitoring.

Monitoring during extracorporeal membrane oxygenation

PURPOSE OF REVIEW

Extracorporeal membrane oxygenation (ECMO) offers advanced mechanical support to patients with severe acute respiratory and/or cardiac failure. Ensuring an adequate therapeutic approach as well as prevention of ECMO-associated complications, by means of timely liberation, forms an essential part of standard ECMO care and is only achievable through continuous monitoring and evaluation. This review focus on the cardiorespiratory monitoring tools that can be used to assess and titrate adequacy of ECMO therapy; as well as methods to assess readiness to wean and/or discontinue ECMO support.

RECENT FINDINGS

Surrogates of tissue perfusion and near infrared spectroscopy are not standards of care but may provide useful information in select patients. Echocardiography allows to determine cannulas position, evaluate cardiac structures, and function, and diagnose complications. Respiratory monitoring is mandatory to achieve lung protective ventilation and identify early lung recovery, surrogate measurements of respiratory effort and ECMO derived parameters are invaluable in optimally managing ECMO patients.

SUMMARY

Novel applications of existing monitoring modalities alongside evolving technological advances enable the advanced monitoring required for safe delivery of ECMO. Liberation trials are necessary to minimize time sensitive ECMO related complications; however, these have yet to be standardized.

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

Background

As lung transplantation (LTx) is becoming a standard treatment for end-stage lung disease, the use of bridging with extracorporeal membrane oxygenation (ECMO) is increasing. We examined the clinical impact of being awake during ECMO as bridging therapy in patients awaiting LTx.

Methods

In this single-center study, we retrospectively reviewed 241 consecutive LTx patients between October 2012 and March 2019; 64 patients received ECMO support while awaiting LTx. We divided into awake and non-awake groups and compared.

Results

Twenty-five patients (39.1%) were awake, and 39 (61.0%) were non-awake. The median age of awake patients was 59.0 (interquartile range, 52.5–63.0) years, and 80% of the group was men. The awake group had better post-operative outcomes than the non-awake group: statistically shorter post-operative intensive care unit length of stay [awake vs. non-awake, 6 (4–8.5) vs. 18 (11–36), p < 0.001], longer ventilator free days [awake vs. non-awake, 24 (17–26) vs. 0 (0–15), p < 0.001], and higher gait ability after LTx (awake vs. non-awake, 92% vs. 59%, p = 0.004), leading to higher 6-month and 1-year lung function (forced expiratory volume in 1 s: awake vs. non-awake, 6-month, 77.5% vs. 61%, p = 0.004, 1-year, 75% vs. 57%, p = 0.013). Furthermore, the awake group had significantly lower 6-month and 1-year mortality rates than the non-awake group (6-month 12% vs. 38.5%, p = 0.022, 1-year 24% vs. 53.8%, p = 0.018).

Conclusions

In patients with end-stage lung disease, considering the long-term and short-term impacts, the awake ECMO strategy could be useful compared with the non-awake ECMO strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01905-7.

Mortality after Lung Transplantation for Children Bridged with Extracorporeal Membrane Oxygenation

RATIONALE

Extracorporeal membrane oxygenation (ECMO) is increasingly used to bridge waitlisted children failing conventional respiratory support to lung transplantation.

OBJECTIVES

To compare in-hospital mortality and a composite outcome of 1-year mortality or re-transplantation in children bridged with ECMO with those on mechanical ventilation (MV), and neither support.

METHODS

The United Network for Organ Sharing (UNOS) was used to analyze lung transplant recipients, aged ≤ 20 y, from January 2004 to August 2019. Recipients were categorized according to level of respiratory support at time of transplant, including ECMO, MV, or neither. Multivariable analysis was used to evaluate support type and in-hospital mortality.

RESULTS

Of 1,014 children undergoing lung transplant, 68 (6.7%) required ECMO as a bridge-to-transplant, 144 (14.2%) MV, and 802 (79.1%) neither. Primary diagnosis in the ECMO cohort included cystic fibrosis (43%), pneumonia/ARDS (10.3%), interstitial pulmonary fibrosis (7.4%) and pulmonary hypertension (5.9%). Number of patients bridged with ECMO increased throughout the study period from none in 2004 to 16.7% in 2018. Multivariable analysis showed bridging with both ECMO (aOR = 3.57; 95% CI: 1.42, 8.97) and MV (aOR = 2.67; 95% CI: 1.26, 5.57) increased in-hospital mortality after lung transplantation. However, there was no difference in composite outcome of mortality and re-transplantation at 1-year between the three groups.

CONCLUSIONS

ECMO to bridge children to lung transplantation has increased. Despite this, ECMO is a high-risk bridge strategy for children awaiting lung transplantation. Future research should target interventions that can be focused on improving survival in these patients.

"Awake" Extracorporeal Membrane Oxygenation Combined With Continuous Renal Replacement Therapy For the Treatment of Severe Chemical Gas Inhalation Lung Injury

Lung injury caused by chemical gas inhalation is a common clinically severe disease that very easily progresses to acute respiratory distress syndrome (ARDS). Traditional respiratory support consists mainly of mechanical ventilation, but the prognosis of this condition is still poor. "Awake" extracorporeal membrane oxygenation (ECMO) maintains oxygenation, improves ventilation, adequately allows the injured lungs to rest, and avoids complications associated with sedation, intubation, and mechanical ventilation. Continuous renal replacement therapy (CRRT) can provide better fluid management and reduce pulmonary edema. Herein, we describe the case of a patient with severe chemical gas inhalation lung injury who failed to respond to traditional mechanical ventilation and was subsequently treated with awake ECMO combined with CRRT.

Awake Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: Which Clinical Issues Should Be Taken Into Consideration

With the goal of protecting injured lungs and extrapulmonary organs, venovenous extracorporeal membrane oxygenation (VV-ECMO) has been increasingly adopted as a rescue therapy for patients with severe acute respiratory distress syndrome (ARDS) when conventional mechanical ventilation failed to provide effective oxygenation and decarbonation. In recent years, it has become a promising approach to respiratory support for awake, non-intubated, spontaneously breathing patients with respiratory failure, referred to as awake ECMO, to avoid possible detrimental effects associated with intubation, mechanical ventilation, and the adjunctive therapies. However, several complex clinical issues should be taken into consideration when initiating and implementing awake ECMO, such as selecting potential patients who appeared to benefit most; techniques to facilitating cannulation and maintain stable ECMO blood flow; approaches to manage pain, agitation, and delirium; and approaches to monitor and modulate respiratory drive. It is worth mentioning that there had also been some inherent disadvantages and limitations of awake ECMO compared to the conventional combination of ECMO and invasive mechanical ventilation. Here, we review the use of ECMO in awake, spontaneously breathing patients with severe ARDS, highlighting the issues involving bedside clinical practice, detailing some of the technical aspects, and summarizing the initial clinical experience gained over the past years.

Carbon Dioxide Elimination During Veno-Venous Extracorporeal Membrane Oxygenation Weaning: A Pilot Study

Veno-venous extracorporeal membrane oxygenation (V-V ECMO) represents a component of the treatment strategy for severe respiratory failure. Clinical evidence on the management of the lung during V-V ECMO are limited just as the consensus regarding timing of weaning. The monitoring of the carbon dioxide (CO2) removal (V'CO2TOT) is subdivided into two components: the membrane lung (ML) and the native lung (NL) are both taken into consideration to evaluate the improvement of the function of the lung and to predict the time to wean off ECMO. We enrolled patients with acute respiratory distress syndrome (ARDS). The V'CO2NL ratio (V'CO2NL/V'CO2TOT) value was calculated based on the distribution of CO2 between the NL and the ML. Of 18 patients, 15 were successfully weaned off of V-V ECMO. In this subgroup, we observed a significant increase in the V'CO2NL ratio comparing the median values of the first and last quartiles (0.32 vs. 0.53, p = 0.0045), without observing any modifications in the ventilation parameters. An increase in the V'CO2NL ratio, independently from any change in ventilation could, despite the limitations of the study, indicate an improvement in pulmonary function and may be used as a weaning index for ECMO.

Awake ECMO without anticoagulation for nearly completely obstructive squamous cell carcinoma of the trachea

Awake veno-venous ECMO without anticoagulation is a safe and successful way to remove a significantly obstructive malignancy in the trachea.

Preoperative risk factors for successful extubation or not after lung transplantation

Background

The purpose of this study was to uncover preoperative risk factors for extubation failure or re-intubation for patients undergoing lung transplant (LTx).

Methods

We performed a retrospective case-control study of LTx from our center between January 2017 and March 2019. Demographic and preoperative characteristics were collected for all included patients. Univariable analysis and multivariable logistic regression were used to analyze risk factors of postoperative unsuccessful extubation following LTx.

Results

Among 107 patients undergoing first LTx investigated, 74 (69.16%) patients who were successfully liberated from mechanical ventilation (MV), and 33 (30.84%) patients who were unsuccessful extubation, which 18 (16.82%) patients suffered from reintubation. associated preoperative factors for unsuccessful extubation following LTx included preoperative extracorporeal membrane oxygenation (ECMO) support [OR =4.631, 95% confidence interval (CI): 1.403–15.286, P=0.012], the preoperative ability of independent expectoration (OR =4.517, 95% CI: 1.498–13.625, P=0.007), the age older than 65-year-old (OR =4.039, 95% CI: 1.154–14.139, P=0.029), and receiving the double lung and heart-LTx (OR =3.390, 95% CI: 0.873–13.162, P=0.078; and OR =16.579, 95% CI: 2.586–106.287, P=0.012, respectively). Further, we investigated the preoperative predicted factors for reintubation. Only the preoperative ECMO remained a significant predictor of re-intubation (OR =4.69, 95% CI: 1.56–15.286, P=0.012).

Conclusions

Preoperative independent sputum clearance, preoperative ECMO, older than 65-year-old, and double lung or heart-LTx were four independent risk factors for unsuccessful extubation. Moreover, preoperative ECMO was the only independent risk factor for reintubation.

Extracorporeal support to achieve lung-protective and diaphragm-protective ventilation

PURPOSE OF REVIEW

Extracorporeal support allows ultraprotective controlled and assisted ventilation, which can prevent lung and diaphragm injury. We focused on most recent findings in the application of extracorporeal support to achieve lung protection and diaphragm- protection, as well as on relevant monitoring.

RECENT FINDINGS

A recent randomized trial comparing the efficacy of extracorporeal support as a rescue therapy to conventional protective mechanical ventilation was stopped for futility but post hoc analyses suggested that extracorporeal support is beneficial for patients with very severe acute respiratory distress syndrome. However, the optimal ventilation settings during extracorporeal support are still debated. It is conceivable that they should enable the highest amount of CO2 removal with lowest mechanical power.Extracorporeal CO2 removal can minimize acidosis and enable the use of ultra-protective lung ventilation strategies when hypoxemia is not a major issue. Moreover, it can protect lung and diaphragm function during assisted ventilation through control of the respiratory effort.Lung mechanics, gas exchange, diaphragm electrical activity, ultrasound, electrical impedance tomography could be integrated into clinical management to define lung and diaphragm protection and guide personalized ventilation settings.

SUMMARY

Technological improvement and the latest evidence indicate that extracorporeal support may be an effective tool for lung and diaphragm protection.

Extracorporeal Membrane Oxygenation (ECMO) in Critically Ill Patients with Coronavirus Disease 2019 (COVID-19) Pneumonia and Acute Respiratory Distress Syndrome (ARDS)

Traced back to December 2019, an unexpected outbreak of a highly contagious new coronavirus pneumonia (COVID-19) has rapidly swept around China and the globe. There have now been an estimated 2 580 000 infections and more than 170 000 fatal cases around the world. The World Health Organization (WHO) estimated that approximately 14% of infections developed into severe disease, 5% were critically ill, and the mortality rate of critically ill patients is reported to be over 50%. The shortage of specific anti-viral treatment and vaccines remains a huge challenge. In COVID-19, refractory hypoxemia is common among the critically ill with acute respiratory distress syndrome (ARDS) despite invasive mechanical ventilation, and is further complicated by respiratory and circulatory failure. This difficult situation calls for the use of extracorporeal membrane oxygenation (ECMO) for assisting respiration and circulation if necessary. This article reviews the pertinent clinical literature, technical guidance, and expert recommendations on use of ECMO in critically ill cases of COVID-19. Here, we present basic knowledge and opinions about COVID-19 and ECMO, review the evidence on ECMO use in Middle East Respiratory Syndrome (MERS) and H1N1 influenza, share the technical guidance and recommendations on use of ECMO in COVID-19, summarize the current use of ECMO against COVID-19 in China, and discuss the issues in use of ECMO in COVID-19.

Extubation and Noninvasive Ventilation of Patients Supported by Extracorporeal Life Support for Cardiogenic Shock: A Single-Center Retrospective Observational Cohort Study

Background:

Temporary extracorporeal life support (ECLS) by venoarterial extracorporeal membrane oxygenation is an emerging therapy for patients with severe, ongoing cardiogenic shock. After stabilization of the hemodynamic status and end-organ function, sedation weaning, extubation, and noninvasive ventilation (NIV) can be attempted. The goal of this study was to analyze the feasibility of extubation and NIV during versus after ECLS for cardiogenic shock.

Methods:

Single-center retrospective observational study of 132 patients undergoing ECLS due to severe cardiogenic shock between January 2015 and December 2016 at a tertiary care university hospital.

Results:

Patients received ECLS due to acute myocardial infarction (20.6%), ongoing cardiogenic shock (15.2%), postoperative low-cardiac-output syndrome (24.2%), and extracorporeal cardiopulmonary resuscitation (40.2%). Overall, intensive care unit survival was 44.7%. Sixty-nine (52.3%) patients could never be extubated. Forty-three (32.6%) were extubated while on ECLS support (group 1) and 20 (15.1%) were extubated after weaning from ECLS (group 2). Patients extubated during ECLS had a significantly shorter total time on ventilator (P = .003, mean difference: −284 hours [95% confidence limits: −83 to −484]) and more invasive ventilation free days (P = .0018; mean difference 8 days [95%CL: 2-14]). Mortality and NIV failure rates were similar between groups.

Conclusions:

Extubation and NIV are feasible in patients who stabilize during ECLS therapy. Further studies need to address whether extubation has the potential to improve patients outcome or if the feasibility to extubate is a surrogate for disease severeness.

Physiology of the Respiratory Drive in ICU Patients: Implications for Diagnosis and Treatment

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Does volatile sedation with sevoflurane allow spontaneous breathing during prolonged prone positioning in intubated ARDS patients? A retrospective observational feasibility trial

Background

Lung-protective ventilation and prolonged prone positioning (PP) are presented as essential in treating acute respiratory distress syndrome (ARDS). The optimal respirator mode, however, remains controversial. Pressure-supported spontaneous breathing (PS) during ARDS provides several advantages, but is difficult to achieve during PP because of respiratory depression as a side effect of sedative drugs. This study was designed to evaluate the feasibility and safety of PS during PP in ARDS patients sedated with inhaled sevoflurane.

Results

Overall, we have observed 4339 h of prone positioning in 62 patients who had a median of four prone episodes during treatment. Within 3948 h (91%), patients were successfully brought into a pressure-supported spontaneous breathing mode. The median duration of each prone episode was 17 h (IQR 3). Median duration of pressure-supported spontaneous breathing per episode was 16 h (IQR 5). Just one self-extubation occurred during 276 episodes of PP.

Conclusions and implications

Pressure-supported spontaneous breathing during prolonged prone positioning in intubated ARDS patients with or without ECMO can be achieved during volatile sedation with sevoflurane. This finding may provide a basis upon which to question the latest dogma in ARDS treatment. Our concept must be further investigated and compared to controlled ventilation with regard to driving pressure, lung-protective parameters, muscle weakness and mortality before it can be routinely applied.

Physiological and Technical Considerations of Extracorporeal CO2 Removal

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

[Application of extracorporeal membrane oxygenation in children with acute respiratory distress syndrome]

The children with acute respiratory distress syndrome (ARDS) usually require ventilatory support treatment. At present, lung protective ventilation strategy is recommended for the treatment of ARDS. Extracorporeal membrane oxygenation (ECMO) can improve oxygenation and remove carbon dioxide by extracorporeal circuit, and can partially or completely take over cardiopulmonary function. ECMO support showed many advantages in treating severe ARDS, such as reducing ventilator-induced lung injury and correcting hypoxemia. Over the past few years, there has been an increase in the use of ECMO for ARDS in children. This paper reviews the applications of ECMO for the treatment of ARDS in children.

[Application of extracorporeal membrane oxygenation in children with acute respiratory distress syndrome]

The children with acute respiratory distress syndrome (ARDS) usually require ventilatory support treatment. At present, lung protective ventilation strategy is recommended for the treatment of ARDS. Extracorporeal membrane oxygenation (ECMO) can improve oxygenation and remove carbon dioxide by extracorporeal circuit, and can partially or completely take over cardiopulmonary function. ECMO support showed many advantages in treating severe ARDS, such as reducing ventilator-induced lung injury and correcting hypoxemia. Over the past few years, there has been an increase in the use of ECMO for ARDS in children. This paper reviews the applications of ECMO for the treatment of ARDS in children.