Extracorporeal Co2 removal in hypercapnic patients at risk of noninvasive ventilation failure: a matched cohort study with historical control

Extracorporeal Carbon Dioxide Removal With the Hemolung in Patients With Acute-on-Chronic Respiratory Failure: A Multicenter Retrospective Cohort Study

Extracorporeal carbon dioxide removal (ECCO2R) devices are increasingly used in treating acute-on-chronic respiratory failure caused by chronic lung diseases. There are no large studies that investigated safety, efficacy, and the independent association of prognostic variables to survival that could define the role of ECCO2R devices in such patients. This multicenter, multinational, retrospective study investigated the efficacy, safety of a single ECCO2R device (Hemolung) in patients with acute on chronic respiratory failure and identified variables independently associated with intensive care unit (ICU) survival. The primary outcome was improvement in blood gasses with the use of Hemolung. Secondary outcomes included reduction in tidal volume, respiratory rate, minute ventilation, survival to ICU discharge, and complication profile. Multivariable regression analysis was used to identify variables that are independently associated with ICU survival. A total of 62 patients were included. There was a significant improvement in pH and partial pressure of carbon dioxide in arterial blood (PaCO2) along with a reduction in respiratory rate, tidal volume, and minute ventilation with Hemolung therapy. The complication profile did not differ between survivors and nonsurvivors. Multivariable analysis identified the duration of Hemolung therapy to be independently associated with survival to ICU discharge (adjusted odds ratio = 1.21; 95% confidence interval [CI] = 1.040-1.518; p = 0.01).

Effects of extracorporeal CO2 removal on gas exchange and ventilator settings: a systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis to evaluate the impact of extracorporeal carbon dioxide removal (ECCO2R) on gas exchange and respiratory settings in critically ill adults with respiratory failure.

METHODS

We conducted a comprehensive database search, including observational studies and randomized controlled trials (RCTs) from January 2000 to March 2022, targeting adult ICU patients undergoing ECCO2R. Primary outcomes were changes in gas exchange and ventilator settings 24 h after ECCO2R initiation, estimated as mean of differences, or proportions for adverse events (AEs); with subgroup analyses for disease indication and technology. Across RCTs, we assessed mortality, length of stay, ventilation days, and AEs as mean differences or odds ratios.

RESULTS

A total of 49 studies encompassing 1672 patients were included. ECCO2R was associated with a significant decrease in PaCO2, plateau pressure, and tidal volume and an increase in pH across all patient groups, at an overall 19% adverse event rate. In ARDS and lung transplant patients, the PaO2/FiO2 ratio increased significantly while ventilator settings were variable. "Higher extraction" systems reduced PaCO2 and respiratory rate more efficiently. The three available RCTs did not demonstrate an effect on mortality, but a significantly longer ICU and hospital stay associated with ECCO2R.

CONCLUSIONS

ECCO2R effectively reduces PaCO2 and acidosis allowing for less invasive ventilation. "Higher extraction" systems may be more efficient to achieve this goal. However, as RCTs have not shown a mortality benefit but increase AEs, ECCO2R's effects on clinical outcome remain unclear. Future studies should target patient groups that may benefit from ECCO2R. PROSPERO Registration No: CRD 42020154110 (on January 24, 2021).

Extracorporeal Carbon Dioxide Removal to Avoid Invasive Ventilation During Exacerbations of Chronic Obstructive Pulmonary Disease: VENT-AVOID Trial - A Randomized Clinical Trial

Rationale: It is unclear whether extracorporeal CO2 removal (ECCO2R) can reduce the rate of intubation or the total time on invasive mechanical ventilation (IMV) in adults experiencing an exacerbation of chronic obstructive pulmonary disease (COPD). Objectives: To determine whether ECCO2R increases the number of ventilator-free days within the first 5 days postrandomization (VFD-5) in exacerbation of COPD in patients who are either failing noninvasive ventilation (NIV) or who are failing to wean from IMV. Methods: This randomized clinical trial was conducted in 41 U.S. institutions (2018-2022) (ClinicalTrials.gov ID: NCT03255057). Subjects were randomized to receive either standard care with venovenous ECCO2R (NIV stratum: n = 26; IMV stratum: n = 32) or standard care alone (NIV stratum: n = 22; IMV stratum: n = 33). Measurements and Main Results: The trial was stopped early because of slow enrollment and enrolled 113 subjects of the planned sample size of 180. There was no significant difference in the median VFD-5 between the arms controlled by strata (P = 0.36). In the NIV stratum, the median VFD-5 for both arms was 5 days (median shift = 0.0; 95% confidence interval [CI]: 0.0-0.0). In the IMV stratum, the median VFD-5 in the standard care and ECCO2R arms were 0.25 and 2 days, respectively; median shift = 0.00 (95% confidence interval: 0.00-1.25). In the NIV stratum, all-cause in-hospital mortality was significantly higher in the ECCO2R arm (22% vs. 0%, P = 0.02) with no difference in the IMV stratum (17% vs. 15%, P = 0.73). Conclusions: In subjects with exacerbation of COPD, the use of ECCO2R compared with standard care did not improve VFD-5. Clinical trial registered with www.clinicaltrials.gov (NCT03255057).

Extracorporeal carbon dioxide removal for patients with acute respiratory failure: a systematic review and meta-analysis

BACKGROUND

Acute respiratory failure (ARF) is a common clinical critical syndrome with substantial mortality. Extracorporeal carbon dioxide removal (ECCO₂R) has been proposed for the treatment of ARF. However, whether ECCO₂R could provide a survival advantage for patients with ARF is still controversial.

METHODS

Electronic databases (PubMed, Embase, Web of Science, and the Cochrane database) were searched from inception to 30 April 2022. Randomized controlled trials (RCTs) and observational studies that examined the following outcomes were included: mortality, length of hospital and ICU stay, intubation and tracheotomy rate, mechanical ventilation days, ventilator-free days (VFDs), respiratory parameters, and reported adverse events.

RESULTS

Four RCTs and five observational studies including 1173 participants with ARF due to COPD or ARDS were included in this meta-analysis. Pooled analyses of related studies showed no significant difference in overall mortality between ECCO₂R and control group, neither in RCTs targeted ARDS or acute hypoxic respiratory failure patients (RR 1.05, 95% CI 0.83 to 1.32, p = 0.70, I² =0.0%), nor in studies targeted patients with ARF secondary to COPD (RR 0.80, 95% CI 0.58 to 1.11, p = 0.19, I² =0.0%). A shorter duration of ICU stay in the ECCO₂R group was only obtained in observational studies (WMD -4.25, p < 0.01), and ECCO₂R was associated with a longer length of hospital stay (p = 0.02). ECCO₂R was associated with lower intubation rate (p < 0.01) and tracheotomy rate (p = 0.01), and shorter mechanical ventilation days (p < 0.01) in comparison to control group in ARF patients with COPD. In addition, an improvement in pH (p = 0.01), PaO2 (p = 0.01), respiratory rate (p < 0.01), and PaCO2 (p = 0.04) was also observed in patients with COPD exacerbations by ECCO₂R therapy. However, the ECCO₂R-related complication rate was high in six of the included studies.

CONCLUSIONS

Our findings from both RCTs and observational studies did not confirm a significant beneficial effect of ECCO₂R therapy on mortality. A shorter length of ICU stay in the ECCO₂R group was only obtained in observational studies, and ECCO₂R was associated with a longer length of hospital stay. ECCO₂R was associated with lower intubation rate and tracheotomy rate, and shorter mechanical ventilation days in ARF patients with COPD. And an improvement in pH, PaO2, respiratory rate and PaCO2 was observed in the ECCO₂R group. However, outcomes largely relied on data from observational studies targeted patients with ARF secondary to COPD, thus further larger high-quality RCTs are desirable to strengthen the evidence on the efficacy and benefits of ECCO₂R for patients with ARF.Key messagesECCO₂R therapy did not confirm a significant beneficial effect on mortality.ECCO₂R was associated with lower intubation and tracheotomy rate, and shorter mechanical ventilation days in patients with ARF secondary to COPD.An improvement in pH, PaO2, respiratory rate, and PaCO2 was observed in ECCO₂R group in patients with COPD exacerbations.Evidence for the future application of ECCO₂R therapy for patients with ARF. The protocol of this meta-analysis was registered on PROSPERO (CRD42022295174).

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

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.

Extracorporeal Carbon Dioxide Removal: From Pathophysiology to Clinical Applications; Focus on Combined Continuous Renal Replacement Therapy

Lung-protective ventilation (LPV) with low tidal volumes can significantly increase the survival of patients with acute respiratory distress syndrome (ARDS) by limiting ventilator-induced lung injuries. However, one of the main concerns regarding the use of LPV is the risk of developing hypercapnia and respiratory acidosis, which may limit the clinical application of this strategy. This is the reason why different extracorporeal CO₂ removal (ECCO₂R) techniques and devices have been developed. They include low-flow or high-flow systems that may be performed with dedicated platforms or, alternatively, combined with continuous renal replacement therapy (CRRT). ECCO₂R has demonstrated effectiveness in controlling PaCO₂ levels, thus allowing LPV in patients with ARDS from different causes, including those affected by Coronavirus disease 2019 (COVID-19). Similarly, the suitability and safety of combined ECCO₂R and CRRT (ECCO₂R-CRRT), which provides CO₂ removal and kidney support simultaneously, have been reported in both retrospective and prospective studies. However, due to the complexity of ARDS patients and the limitations of current evidence, the actual impact of ECCO₂R on patient outcome still remains to be defined. In this review, we discuss the main principles of ECCO₂R and its clinical application in ARDS patients, in particular looking at clinical experiences of combined ECCO₂R-CRRT treatments.

Extracorporeal carbon dioxide removal for acute respiratory failure: a review of potential indications, clinical practice and open research questions

Extracorporeal carbon dioxide removal (ECCO₂R) is a form of extracorporeal life support (ECLS) largely aimed at removing carbon dioxide in patients with acute hypoxemic or acute hypercapnic respiratory failure, so as to minimize respiratory acidosis, allowing more lung protective ventilatory settings which should decrease ventilator-induced lung injury. ECCO₂R is increasingly being used despite the lack of high-quality evidence, while complications associated with the technique remain an issue of concern. This review explains the physiological basis underlying the use of ECCO₂R, reviews the evidence regarding indications and contraindications, patient management and complications, and addresses organizational and ethical considerations. The indications and the risk-to-benefit ratio of this technique should now be carefully evaluated using structured national or international registries and large randomized trials.

Intraoperative use of extracorporeal CO2 removal (ECCO2R) and emergency ECMO requirement in patients undergoing lung transplant: a case-matched cohort retrospective study

BACKGROUND

The use of extracorporeal carbon dioxide removal (ECCO₂R) is less invasive than extracorporeal membrane oxygenation (ECMO), and intraoperative control of gas exchange could be feasible. The aim of this study in intermediate intraoperative severity patients undergoing LT was to assess the role of intraoperative ECCO₂R on emergency ECMO requirement in patients.

METHODS

Thirty-eight consecutive patients undergoing lung transplantation (LT) with "intermediate" intraoperative severity in the intervals 2007 to 2010 or 2011 to 2014 were analyzed as historical comparison of case-matched cohort retrospective study. The "intermediate" intraoperative severity was defined as the development of intraoperative severe respiratory acidosis with maintained oxygenation function (i.e., pH <7.25, PaCO₂ >60 mmHg, and PaO₂/FiO₂ >150), not associated with hemodynamic instability. Of these 38 patients, twenty-three patients were treated in the 2007-2010 interval by receiving "standard intraoperative treatment," while 15 patients were treated in the 2011-2014 interval by receiving "standard intraoperative treatment + ECCO₂R."

RESULTS

ECMO requirement was more frequent among patients that received "standard intraoperative treatment" alone than in those treated with "standard intraoperative treatment + ECCO₂R" (17/23 vs. 3/15; p = 0.004). The use of ECCO₂R improved pH and PaCO₂ while mean pulmonary artery pressure (mPAP) decreased.

CONCLUSION

In intermediate intraoperative severity patients, the use of ECCO₂R reduces the ECMO requirement.

Extracorporeal CO2 removal in acute exacerbation of COPD unresponsive to non-invasive ventilation

Background

The gold-standard treatment for acute exacerbation of chronic obstructive pulmonary disease (ae-COPD) is non-invasive ventilation (NIV). However, NIV failures may be observed, and invasive mechanical ventilation (IMV) is required. Extracorporeal CO₂ removal (ECCO₂R) devices can be an alternative to intubation. The aim of the study was to assess ECCO₂R effectiveness and safety.

Methods

Patients with consecutive ae-COPD who experienced NIV failure were retrospectively assessed over two periods of time: before and after ECCO₂R device implementation in our ICU in 2015 (Xenios AG).

Results

Both groups (ECCO₂R: n=26, control group: n=25) were comparable at baseline, except for BMI, which was significantly higher in the ECCO₂R group (30 kg/m² vs 25 kg/m²). pH and PaCO₂ significantly improved in both groups. The mean time on ECCO₂R was 5.4 days versus 27 days for IMV in the control group. Four patients required IMV in the ECCO₂R group, of whom three received IMV after ECCO₂R weaning. Seven major bleeding events were observed with ECCO₂R, but only three led to premature discontinuation of ECCO₂R. Eight cases of ventilator-associated pneumonia were observed in the control group. Mean time spent in the ICU and mean hospital stay in the ECCO₂R and control groups were, respectively, 18 vs 30 days, 29 vs 49 days, and the 90-day mortality rates were 15% vs 28%.

Conclusions

ECCO₂R was associated with significant improvement of pH and PaCO₂ in patients with ae-COPD failing NIV therapy. It also led to avoiding intubation in 85% of cases, with low complication rates.

Trial registration number

ClinicalTrials.gov, NCT04882410. Date of registration 12 May 2021, retrospectively registered.

https://www.clinicaltrials.gov/ct2/show/NCT04882410.

Extracorporeal carbon dioxide removal for treatment of exacerbated chronic obstructive pulmonary disease (ORION): study protocol for a randomised controlled trial

Background

Hypercapnic exacerbations are severe complications of chronic obstructive pulmonary disease (COPD), characterized by negative impact on prognosis, quality of life and healthcare costs. The present standard of care for acute exacerbations of COPD is non-invasive ventilation; when it fails, the use of invasive mechanical ventilation is inevitable, but is associated with extremely poor prognosis. Extracorporeal circuits designed to remove CO₂ (ECCO₂R) may enhance the efficacy of NIV to remove CO₂ and avoid the worsening of respiratory acidosis, which inevitably leads to failure of non-invasive ventilation. Although the use of ECCO₂R for acute exacerbations of COPD is steadily increasing, solid evidence on its efficacy and safety is scarce, thus the need for a randomized controlled trial.

Methods

multicenter randomized controlled unblinded clinical trial including 284 (142 per arm) patients with acute hypercapnic respiratory failure caused by exacerbation of COPD, requiring respiratory support with NIV. The primary outcome is event free survival at 28 days, a composite outcome defined by survival in absence of prolonged mechanical ventilation, severe hypoxemia, septic shock and second episode of COPD exacerbation. Secondary outcomes are incidence of endotracheal intubation and tracheostomy, intensive care and hospital length-of-stay and 90-day mortality.

Discussion

Acute exacerbations of COPD represent a significant burden in terms of prognosis, quality of life and healthcare costs. Lack definite evidence despite increasing use of ECCO₂R justifies a randomized trial to evaluate whether patients with acute hypercapnic acidosis not responsive to NIV should undergo invasive mechanical ventilation (with all serious related risks) or be treated with ECCO₂R to avoid invasive ventilation but be exposed to possible adverse events of ECCO₂R. Owing to its pragmatic nature, sample size and composite primary outcome, this trial aims at providing valuable answers to relevant questions for clinical treatment of acute exacerbations of COPD.

Trial registration

ClinicalTrials.gov, NCT04582799. Registered 12 October 2020, .

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05692-w.

Extracorporeal membrane oxygenation in lung transplantation: Indications, techniques and results

The use of extracorporeal membrane oxygenation (ECMO) in the field of lung transplantation has rapidly expanded over the past 30 years. It has become an important tool in an increasing number of specialized centers as a bridge to transplantation and in the intra-operative and/or post-operative setting. ECMO is an extremely versatile tool in the field of lung transplantation as it can be used and adapted in different configurations with several potential cannulation sites according to the specific need of the recipient. For example, patients who need to be bridged to lung transplantation often have hypercapnic respiratory failure that may preferably benefit from veno-venous (VV) ECMO or peripheral veno-arterial (VA) ECMO in the case of hemodynamic instability. Moreover, in an intra-operative setting, VV ECMO can be maintained or switched to a VA ECMO. The routine use of intra-operative ECMO and its eventual prolongation in the post-operative period has been widely investigated in recent years by several important lung transplantation centers in order to assess the graft function and its potential protective role on primary graft dysfunction and on ischemia-reperfusion injury. This review will assess the current evidence on the role of ECMO in the different phases of lung transplantation, while analyzing different studies on pre, intra- and post-operative utilization of this extracorporeal support.

Combined Renal-Pulmonary Extracorporeal Support with Low Blood Flow Techniques: A Retrospective Observational Study (CICERO Study)

BACKGROUND

Critically ill patients with acute respiratory failure frequently present concomitant lung and kidney injury, within a multiorgan failure condition due to local and systemic mediators. To face this issue, extracorporeal carbon dioxide removal (ECCO2R) systems have been integrated into continuous renal replacement therapy (CRRT) platforms to provide a combined organ support, with efficient clearance of CO2 with very low extracorporeal blood flows (<400 mL/min).

OBJECTIVES

To evaluate efficacy and safety of combined ECCO2R-CRRT support with PrismaLung®-Prismaflex® in patients affected by hypercapnic respiratory acidosis associated with AKI in a second level intensive care unit.

METHODS

We carried out a retrospective observational study enrolling patients submitted to PrismaLung®-Prismaflex® due to mild to moderate acute respiratory distress syndrome (ARDS) or acute exacerbation of chronic obstructive pulmonary disease (aeCOPD). The primary endpoints were the shift to protective ventilation and extubation of mechanically ventilated patients and the shift to invasive mechanical ventilation of patients receiving noninvasive ventilation (NIV). Clinical-laboratoristic data and operational characteristics of ECCO2R-CRRT were recorded.

RESULTS

Overall, 12/17 patients on mechanical ventilation shifted to protective ventilation, CO2 clearance was satisfactorily maintained during the whole observational period, and pH was rapidly corrected. Treatment prevented NIV failure in 4 out of 5 patients. No treatment-related complications were recorded.

CONCLUSION

ECCO2R-CRRT was effective and safe in patients with aeCOPD and ARDS associated with AKI.

Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO2 clearance within the Maquet Quadrox-iD oxygenator

While hypercapnia is typically well treated with modern membrane oxygenators, there are cases where respiratory acidosis persists despite maximal extracorporeal membrane oxygenation support. To better understand the physiology of gas exchange within the membrane oxygenator, CO₂ clearance within an adult Maquet Quadrox-iD oxygenator was evaluated at varying blood CO₂ tensions and V/Q ratios in an ex vivo extracorporeal membrane oxygenation circuit. A closed blood-primed circuit incorporating two Maquet Quadrox-iD oxygenators in series was attached to a Maquet PLS Rotaflow pump. A varying blend of CO₂ and air was connected to the first oxygenator to provide different levels of pre-oxygenator blood CO₂ levels (P_vCO₂) to the second oxygenator. Varying sweep gas flows of 100% O₂ were connected to the second oxygenator to provide different V/Q ratios. Exhaust CO₂ was directly measured, and then VCO₂ and oxygenator dead space fraction (V_D/V_T) were calculated. VCO₂ increased with increasing gas flow rates with plateauing at V/Q ratios greater than 4.0. Exhaust CO₂ increased with P_vCO₂ in a linear fashion with the slope of the line decreasing at high V/Q ratios. Oxygenator dead space fraction varied with V/Q ratio-at lower ratios, dead space fraction was 0.3-0.4 and rose to 0.8-0.9 at ratios greater than 4.0. Within the Maquet Quadrox-iD oxygenator, CO₂ clearance is limited at high V/Q ratios and correlated with elevated oxygenator dead space fraction. These findings have important implications for patients requiring high levels of extracorporeal membrane oxygenation support.

A bi-centric experience of extracorporeal carbon dioxide removal (ECCO2 R) for acute hypercapnic respiratory failure following allogeneic hematopoietic stem cell transplantation

Acute respiratory failure (ARF) is the main reason for ICU admission following allogeneic hematopoietic stem cell transplantation (HSCT). Extracorporeal CO₂ removal (ECCO₂R) can be used as an adjunct to mechanical ventilation in patients with severe hypercapnia but has not been assessed in HSCT recipients. Retrospective analysis of all allogeneic HSCT recipients ≥18 years treated with ECCO₂R at two HSCT centers. 11 patients (m:f = 4:7, median age: 45 [IQR: 32‐58] years) were analyzed. Acute leukemia was the underlying hematologic malignancy in all patients. The time from HSCT to ICU admission was 37 [8‐79] months, and 9/11 (82%) suffered from chronic graft‐versus‐host disease (GVHD) with lung involvement. Pneumonia was the most frequent reason for ventilatory decompensation (n = 9). ECCO₂R was initiated for severe hypercapnia (P_aCO₂: 96 [84‐115] mm Hg; pH: 7.13 [7.09‐7.27]) despite aggressive mechanical ventilation (invasive, n = 9; non‐invasive, n = 2). ECCO₂R effectively resolved blood gas disturbances in all patients, but only 2/11 (18%) could be weaned off ventilatory support, and one (9%) patient survived hospital discharge. Progressive respiratory and multiorgan dysfunction were the main reasons for treatment failure. ECCO₂R was technically feasible but resulted in a low survival rate in our cohort. A better understanding of the prognosis of ARF in patients with chronic GVHD and lung involvement is necessary before its use can be reconsidered in this setting.

Chronic obstructive pulmonary disease exacerbation fundamentals: Diagnosis, treatment, prevention and disease impact

In chronic obstructive pulmonary disease (COPD), exacerbations (ECOPD), characterized by an acute deterioration in respiratory symptoms, are fundamental events impacting negatively upon disease progression, comorbidities, wellbeing and mortality. ECOPD also represent the largest component of the socioeconomic burden of COPD. ECOPDs are currently defined as acute worsening of respiratory symptoms that require additional therapy. Definitions that require worsening of dyspnoea and sputum volume/purulence assume that acute infections, especially respiratory viral infections, and/or exposure to pollutants are the main cause of ECOPD. But other factors may contribute to ECOPD, such as the exacerbation of other respiratory diseases and non-respiratory diseases (e.g., heart failure, thromboembolism). The complexity of worsening dyspnoea has suggested a need to improve the definition of ECOPD using objective measurements such as blood counts and C-reactive protein to improve accuracy of diagnosis and a personalized approach to management. There are three time points when we can intervene to improve outcomes: acutely, to attenuate the length and severity of an established exacerbation; in the aftermath, to prevent early recurrence and readmission, which are common, and in the long-term, establishing preventative measures that reduce the risk of future events. Acute management includes interventions such as corticosteroids or antibiotics and measures to support the respiratory system, including non-invasive ventilation (NIV). Current therapies are broad and better understanding of clinical phenotypes and biomarkers may help to establish a more tailored approach, for example in relation to antibiotic prescription. Other unmet needs include effective treatment for viruses, which commonly cause exacerbations. Preventing early recurrence and readmission to hospital is important and the benefits of interventions such as antibiotics or anti-inflammatories in this period are not established. Domiciliary NIV in those patients who are persistently hypercapnic following discharge and pulmonary rehabilitation can have a positive impact. For long-term prevention, inhaled therapy is key. Dual bronchodilators reduce exacerbation frequency but in patients with continuing exacerbations, triple therapy should be considered, especially if blood eosinophils are elevated. Other options include phosphodiesterase inhibitors and macrolide antibiotics. ECOPD are a key component of the assessment of COPD severity and future outcomes (quality of life, hospitalisations, health care resource utilization, mortality) and are a central component in pharmacological management decisions. Targeted therapies directed towards specific pathways of inflammation are being explored in exacerbation prevention, and this is a promising avenue for future research.

Physiological Basis of Extracorporeal Membrane Oxygenation and Extracorporeal Carbon Dioxide Removal in Respiratory Failure

Extracorporeal life support (ECLS) for severe respiratory failure has seen an exponential growth in recent years. Extracorporeal membrane oxygenation (ECMO) and extracorporeal CO2 removal (ECCO2R) represent two modalities that can provide full or partial support of the native lung function, when mechanical ventilation is either unable to achieve sufficient gas exchange to meet metabolic demands, or when its intensity is considered injurious. While the use of ECMO has defined indications in clinical practice, ECCO2R remains a promising technique, whose safety and efficacy are still being investigated. Understanding the physiological principles of gas exchange during respiratory ECLS and the interactions with native gas exchange and haemodynamics are essential for the safe applications of these techniques in clinical practice. In this review, we will present the physiological basis of gas exchange in ECMO and ECCO2R, and the implications of their interaction with native lung function. We will also discuss the rationale for their use in clinical practice, their current advances, and future directions.

The use of extracorporeal CO2 removal in acute respiratory failure

Background

Chronic obstructive pulmonary disease (COPD) exacerbation and protective mechanical ventilation of acute respiratory distress syndrome (ARDS) patients induce hypercapnic respiratory acidosis.

Main text

Extracorporeal carbon dioxide removal (ECCO₂R) aims to eliminate blood CO₂ to fight against the adverse effects of hypercapnia and related acidosis. Hypercapnia has deleterious extrapulmonary consequences, particularly for the brain. In addition, in the lung, hypercapnia leads to: lower pH, pulmonary vasoconstriction, increases in right ventricular afterload, acute cor pulmonale. Moreover, hypercapnic acidosis may further damage the lungs by increasing both nitric oxide production and inflammation and altering alveolar epithelial cells. During an exacerbation of COPD, relieving the native lungs of at least a portion of the CO₂ could potentially reduce the patient's respiratory work, Instead of mechanically increasing alveolar ventilation with MV in an already hyperinflated lung to increase CO₂ removal, the use of ECCO₂R may allow a decrease in respiratory volume and respiratory rate, resulting in improvement of lung mechanic. Thus, the use of ECCO₂R may prevent noninvasive ventilation failure and allow intubated patients to be weaned off mechanical ventilation. In ARDS patients, ECCO₂R may be used to promote an ultraprotective ventilation in allowing to lower tidal volume, plateau (Pplat) and driving pressures, parameters that have identified as a major risk factors for mortality. However, although ECCO₂R appears to be effective in improving gas exchange and possibly in reducing the rate of endotracheal intubation and allowing more protective ventilation, its use may have pulmonary and hemodynamic consequences and may be associated with complications.

Conclusion

In selected patients, ECCO₂R may be a promising adjunctive therapeutic strategy for the management of patients with severe COPD exacerbation and for the establishment of protective or ultraprotective ventilation in patients with ARDS without prognosis-threatening hypoxemia.

Evaluation of a New Extracorporeal CO2 Removal Device in an Experimental Setting

Background: Ultra-protective lung ventilation in acute respiratory distress syndrome or early weaning and/or avoidance of mechanical ventilation in decompensated chronic obstructive pulmonary disease may be facilitated by the use of extracorporeal CO₂ removal (ECCO₂R). We tested the CO₂ removal performance of a new ECCO₂R (CO₂RESET) device in an experimental animal model. Methods: Three healthy pigs were mechanically ventilated and connected to the CO₂RESET device (surface area = 1.8 m², EUROSETS S.r.l., Medolla, Italy). Respiratory settings were adjusted to induce respiratory acidosis with the adjunct of an external source of pure CO₂ (target pre membrane lung venous PCO₂ (P_preCO₂): 80–120 mmHg). The amount of CO₂ removed (VCO₂, mL/min) by the membrane lung was assessed directly by the ECCO₂R device. Results: Before the initiation of ECCO₂R, the median P_preCO₂ was 102.50 (95.30–118.20) mmHg. Using fixed incremental steps of the sweep gas flow and maintaining a fixed blood flow of 600 mL/min, VCO₂ progressively increased from 0 mL/min (gas flow of 0 mL/min) to 170.00 (160.00–200.00) mL/min at a gas flow of 10 L/min. In particular, a high increase of VCO₂ was observed increasing the gas flow from 0 to 2 L/min, then, VCO₂ tended to progressively achieve a steady-state for higher gas flows. No animal or pump complications were observed. Conclusions: Medium-flow ECCO₂R devices with a blood flow of 600 mL/min and a high surface membrane lung (1.8 m²) provided a high VCO₂ using moderate sweep gas flows (i.e., >2 L/min) in an experimental swine models with healthy lungs.

How to ventilate obstructive and asthmatic patients

Exacerbations are part of the natural history of chronic obstructive pulmonary disease and asthma. Severe exacerbations can cause acute respiratory failure, which may ultimately require mechanical ventilation. This review summarizes practical ventilator strategies for the management of patients with obstructive airway disease. Such strategies include non-invasive mechanical ventilation to prevent intubation, invasive mechanical ventilation, from the time of intubation to weaning, and strategies intended to prevent post-extubation acute respiratory failure. The role of tracheostomy, the long-term prognosis, and potential future adjunctive strategies are also discussed. Finally, the physiological background that underlies these strategies is detailed.

Physiological effects of adding ECCO2R to invasive mechanical ventilation for COPD exacerbations

Background

Extracorporeal CO₂ removal (ECCO₂R) could be a valuable additional modality for invasive mechanical ventilation (IMV) in COPD patients suffering from severe acute exacerbation (AE). We aimed to evaluate in such patients the effects of a low-to-middle extracorporeal blood flow device on both gas exchanges and dynamic hyperinflation, as well as on work of breathing (WOB) during the IMV weaning process.

Study design and methods

Open prospective interventional study in 12 deeply sedated IMV AE-COPD patients studied before and after ECCO₂R initiation. Gas exchange and dynamic hyperinflation were compared after stabilization without and with ECCO₂R (Hemolung, Alung, Pittsburgh, USA) combined with a specific adjustment algorithm of the respiratory rate (RR) designed to improve arterial pH. When possible, WOB with and without ECCO₂R was measured at the end of the weaning process. Due to study size, results are expressed as median (IQR) and a non-parametric approach was adopted.

Results

An improvement in PaCO₂, from 68 (63; 76) to 49 (46; 55) mmHg, p = 0.0005, and in pH, from 7.25 (7.23; 7.29) to 7.35 (7.32; 7.40), p = 0.0005, was observed after ECCO₂R initiation and adjustment of respiratory rate, while intrinsic PEEP and Functional Residual Capacity remained unchanged, from 9.0 (7.0; 10.0) to 8.0 (5.0; 9.0) cmH₂O and from 3604 (2631; 4850) to 3338 (2633; 4848) mL, p = 0.1191 and p = 0.3013, respectively. WOB measurements were possible in 5 patients, indicating near-significant higher values after stopping ECCO₂R: 11.7 (7.5; 15.0) versus 22.6 (13.9; 34.7) Joules/min., p = 0.0625 and 1.1 (0.8; 1.4) versus 1.5 (0.9; 2.8) Joules/L, p = 0.0625. Three patients died in-ICU. Other patients were successfully hospital-discharged.

Conclusions

Using a formalized protocol of RR adjustment, ECCO₂R permitted to effectively improve pH and diminish PaCO₂ at the early phase of IMV in 12 AE-COPD patients, but not to diminish dynamic hyperinflation in the whole group. A trend toward a decrease in WOB was also observed during the weaning process.

Trial registration ClinicalTrials.gov: Identifier: NCT02586948.

ECCO2R therapy in the ICU: consensus of a European round table meeting

Background

With recent advances in technology, patients with acute respiratory distress syndrome (ARDS) and severe acute exacerbations of chronic obstructive pulmonary disease (ae-COPD) could benefit from extracorporeal CO₂ removal (ECCO₂R). However, current evidence in these indications is limited. A European ECCO₂R Expert Round Table Meeting was convened to further explore the potential for this treatment approach.

Methods

A modified Delphi-based method was used to collate European experts’ views to better understand how ECCO₂R therapy is applied, identify how patients are selected and how treatment decisions are made, as well as to identify any points of consensus.

Results

Fourteen participants were selected based on known clinical expertise in critical care and in providing respiratory support with ECCO₂R or extracorporeal membrane oxygenation. ARDS was considered the primary indication for ECCO₂R therapy (n = 7), while 3 participants considered ae-COPD the primary indication. The group agreed that the primary treatment goal of ECCO₂R therapy in patients with ARDS was to apply ultra-protective lung ventilation via managing CO₂ levels. Driving pressure (≥ 14 cmH₂O) followed by plateau pressure (P_plat; ≥ 25 cmH₂O) was considered the most important criteria for ECCO₂R initiation. Key treatment targets for patients with ARDS undergoing ECCO₂R included pH (> 7.30), respiratory rate (< 25 or < 20 breaths/min), driving pressure (< 14 cmH₂O) and P_plat (< 25 cmH₂O). In ae-COPD, there was consensus that, in patients at risk of non-invasive ventilation (NIV) failure, no decrease in PaCO₂ and no decrease in respiratory rate were key criteria for initiating ECCO₂R therapy. Key treatment targets in ae-COPD were patient comfort, pH (> 7.30–7.35), respiratory rate (< 20–25 breaths/min), decrease of PaCO₂ (by 10–20%), weaning from NIV, decrease in HCO₃⁻ and maintaining haemodynamic stability. Consensus was reached on weaning protocols for both indications. Anticoagulation with intravenous unfractionated heparin was the strategy preferred by the group.

Conclusions

Insights from this group of experienced physicians suggest that ECCO₂R therapy may be an effective supportive treatment for adults with ARDS or ae-COPD. Further evidence from randomised clinical trials and/or high-quality prospective studies is needed to better guide decision making.

Extracorporeal CO2 removal (ECCO2R) in patients with stable COPD with chronic hypercapnia: a proof-of-concept study

Domiciliary non-invasive ventilation (NIV) effectively reduces arterial carbon dioxide pressure (PaCO2) in patients with stable hypercapnic chronic obstructive pulmonary disease, but a consistent percentage of them may remain hypercapnic. We hypothesised that extracorporeal CO2 removal (ECCO2R) may lower their PaCO2. Ten patients hypercapnic despite ≥6 months of NIV underwent a 24-hour trial of ECCO2R. Six patients completed the ECCO2R-trial with a PaCO2 drop ranging between 23% and 47%. Time to return to baseline after interruption ranged 48–96 hours. In four patients, mechanical events led to ECCO2R premature interruption, despite a decreased in PaCO2. This time window ‘free’ from hypercapnia might allow to propose the concept of ‘CO2 dialysis’.

Invasive Mechanical Ventilation in Chronic Obstructive Pulmonary Disease Exacerbations

Chronic obstructive pulmonary disease (COPD) continues to be an important cause of morbidity, mortality, and health care costs worldwide. Although there exist some heterogeneity between patients, the course of COPD is characterized by recurrent acute exacerbations, which are among the most common causes of medical admission to hospital. Patients with frequent exacerbations have accelerated lung function decline, worse quality of life, and greater mortality. Therefore, interest is growing in assessing the effectiveness of interventions used to treat exacerbations. The present review summarizes the current evidence regarding the use of ventilatory management to treat COPD and the implementation of novel cost-effective strategies, such as high-flow oxygenation or extracorporeal carbon dioxide removal to improve clinical outcomes and functional recovery in this disease and to reduce the associated costs.

Extracorporeal Membrane Oxygenation for Respiratory Failure

This review focuses on the use of veno-venous extracorporeal membrane oxygenation for respiratory failure across all blood flow ranges. Starting with a short overview of historical development, aspects of the physiology of gas exchange (i.e., oxygenation and decarboxylation) during extracorporeal circulation are discussed. The mechanisms of phenomena such as recirculation and shunt playing an important role in daily clinical practice are explained.Treatment of refractory and symptomatic hypoxemic respiratory failure (e.g., acute respiratory distress syndrome [ARDS]) currently represents the main indication for high-flow veno-venous-extracorporeal membrane oxygenation. On the other hand, lower-flow extracorporeal carbon dioxide removal might potentially help to avoid or attenuate ventilator-induced lung injury by allowing reduction of the energy load (i.e., driving pressure, mechanical power) transmitted to the lungs during mechanical ventilation or spontaneous ventilation. In the latter context, extracorporeal carbon dioxide removal plays an emerging role in the treatment of chronic obstructive pulmonary disease patients during acute exacerbations. Both applications of extracorporeal lung support raise important ethical considerations, such as likelihood of ultimate futility and end-of-life decision-making. The review concludes with a brief overview of potential technical developments and persistent challenges.

In vitro characterization of PrismaLung+: a novel ECCO2R device

BACKGROUND

Invasive mechanical ventilation is lifesaving in the setting of severe acute respiratory failure but can cause ventilation-induced lung injury. Advances in extracorporeal CO₂ removal (ECCO₂R) technologies may facilitate more protective lung ventilation in acute respiratory distress syndrome, and enable earlier weaning and/or avoid invasive mechanical ventilation entirely in chronic obstructive pulmonary disease exacerbations. We evaluated the in vitro CO₂ removal capacity of the novel PrismaLung+ ECCO₂R device compared with two existing gas exchangers.

METHODS

The in vitro CO₂ removal capacity of the PrismaLung+ (surface area 0.8 m², Baxter) was compared with the PrismaLung (surface area 0.35 m², Baxter) and A.L.ONE (surface area 1.35 m², Eurosets) devices, using a closed-loop bovine blood-perfused extracorporeal circuit. The efficacy of each device was measured at varying pCO₂ inlet (p_inCO₂) levels (45, 60, and 80 mmHg) and blood flow rates (Q_B) of 200-450 mL/min; the PrismaLung+ and A.L.ONE devices were also tested at a Q_B of 600 mL/min. The amount of CO₂ removed by each device was assessed by measurement of the CO₂ infused to maintain circuit equilibrium (CO₂ infusion method) and compared with measured CO₂ concentrations in the inlet and outlet of the CO₂ removal device (blood gas analysis method).

RESULTS

The PrismaLung+ device performed similarly to the A.L.ONE device, with both devices demonstrating CO₂ removal rates ~ 50% greater than the PrismaLung device. CO₂ removal rates were 73 ± 4.0, 44 ± 2.5, and 72 ± 1.9 mL/min, for PrismaLung+, PrismaLung, and A.L.ONE, respectively, at Q_B 300 mL/min and p_inCO₂ 45 mmHg. A Bland-Altman plot demonstrated that the CO₂ infusion method was comparable to the blood gas analysis method for calculating CO₂ removal. The resistance to blood flow across the test device, as measured by pressure drop, varied as a function of blood flow rate, and was greatest for PrismaLung and lowest for the A.L.ONE device.

CONCLUSIONS

The newly developed PrismaLung+ performed more effectively than PrismaLung, with performance of CO₂ removal comparable to A.L.ONE at the flow rates tested, despite the smaller membrane surface area of PrismaLung+ versus A.L.ONE. Clinical testing of PrismaLung+ is warranted to further characterize its performance.

The use of extracorporeal carbon dioxide removal in acute chronic obstructive pulmonary disease exacerbation: a narrative review

Chronic obstructive pulmonary disease (COPD) exacerbation induces hypercapnic respiratory acidosis. Extracorporeal carbon dioxide removal (ECCO2R) aims to eliminate blood carbon dioxide (CO2) in order to reduce adverse effects from hypercapnia and the related acidosis. Hypercapnia has deleterious extra-pulmonary consequences in increasing intracranial pressure and inducing and/or worsening right heart failure. During COPD exacerbation, the use of ECCO2R may improve the efficacy of non-invasive ventilation (NIV) in terms of CO2 removal, decrease respiratory rate and reduce dynamic hyperinflation and intrinsic positive end expiratory pressure, which all contribute to increasing dead space. Moreover, ECCO2R may prevent NIV failure while facilitating the weaning of intubated patients from mechanical ventilation. In this review of the literature, the authors will present the current knowledge on the pathophysiology related to COPD, the principles of the ECCO2R technique and its role in acute and severe decompensation of COPD. However, despite technical advances, there are only case series in the literature and few prospective studies to clearly establish the role of ECCO2R in acute and severe COPD decompensation.

Ventilator Support and Oxygen Therapy in Palliative and End-of-Life Care in the Elderly

Elderly patients suffering from chronic cardio-pulmonary diseases commonly experience acute respiratory failure. As in younger patients, a well-known therapeutic approach of noninvasive mechanical ventilation is able to prevent orotracheal intubation in a large number of severe scenarios in elderly patients. In addition, this type of ventilation is frequently applied in elderly patients who refuse intubation for invasive mechanical ventilation. The rate of failure of noninvasive ventilation may be reduced by means of the integration of new technological devices (i.e., high-flow nasal cannula, extracorporeal CO₂ removal, cough assistance and high-frequency chest wall oscillation, and fiberoptic bronchoscopy). Ethical issues with end-of-life decisions and the choice of the environment are not clearly defined in the treatment of elderly with acute respiratory insufficiency.

Update on extracorporeal carbon dioxide removal: a comprehensive review on principles, indications, efficiency, and complications

TECHNOLOGY

Extracorporeal carbon dioxide removal means the removal of carbon dioxide from the blood across a gas exchange membrane without substantially improving oxygenation. Carbon dioxide removal is possible with substantially less extracorporeal blood flow than needed for oxygenation. Techniques for extracorporeal carbon dioxide removal include (1) pumpless arterio-venous circuits, (2) low-flow venovenous circuits based on the technology of continuous renal replacement therapy, and (3) venovenous circuits based on extracorporeal membrane oxygenation technology.

INDICATIONS

Extracorporeal carbon dioxide removal has been shown to enable more protective ventilation in acute respiratory distress syndrome patients, even beyond the so-called "protective" level. Although experimental data suggest a benefit on ventilator induced lung injury, no hard clinical evidence with respect to improved outcome exists. In addition, extracorporeal carbon dioxide removal is a tool to avoid intubation and mechanical ventilation in patients with acute exacerbated chronic obstructive pulmonary disease failing non-invasive ventilation. This concept has been shown to be effective in 56-90% of patients. Extracorporeal carbon dioxide removal has also been used in ventilated patients with hypercapnic respiratory failure to correct acidosis, unload respiratory muscle burden, and facilitate weaning. In patients suffering from terminal fibrosis awaiting lung transplantation, extracorporeal carbon dioxide removal is able to correct acidosis and enable spontaneous breathing during bridging. Keeping these patients awake, ambulatory, and breathing spontaneously is associated with favorable outcome.

COMPLICATIONS

Complications of extracorporeal carbon dioxide removal are mostly associated with vascular access and deranged hemostasis leading to bleeding. Although the spectrum of complications may differ, no technology offers advantages with respect to rate and severity of complications. So called "high-extraction systems" working with higher blood flows and larger membranes may be more effective with respect to clinical goals.

Safety and Efficacy of a Novel Pneumatically Driven Extracorporeal Membrane Oxygenation Device

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is rapidly becoming a mainstream technology for lung or heart/lung support. Current ECMO devices mostly consist of a power-driven centrifugal pump and a dedicated oxygenator. We studied the safety and efficacy of a novel, fully pneumatically driven ECMO device, which could be used in both venovenous or venoarterial mode in an animal model.

METHODS

Six healthy, awake sheep were treated with the Mobybox ECMO device (Hemovent, Aachen, Germany) over a 7-day period in a venovenous mode. Gas exchange, coagulation parameters, and safety were assessed.

RESULTS

Using a blood flow rate of 2 L/min and a low sweep gas flow rate of 0.3 L/min, the PCO₂ ranged from 38 to 44 mm Hg pre oxygenator and dropped to 32 to 36 mm Hg post oxygenator, whereas the PaO₂ post oxygenator increased to 600 mm Hg. Higher levels of sweep gas flow resulted in cessation of spontaneous breathing in some animals, consistent with high-efficiency carbon dioxide removal; thus, the sweep gas flow rate was maintained at a low level. Platelets dropped from 177 ± 53/μL to 107 ± 28/μL on day 2, while returning to baseline by day 7 (180 ± 51/μL). Plasma-free hemoglobin remained low (2-9 mg/dL), whereas fibrinogen slightly increased, and then remained stable throughout the period. Neither the pump nor the oxygenator showed any visible clotting after 7 days.

CONCLUSIONS

The pneumatically driven ECMO device provided excellent safety and physiologic efficacy in a 7-day sheep experiment without visible clotting, hemolysis, or sustained reductions in fibrinogen or platelets.

Intraoperative extracorporeal carbon dioxide removal support for minimally invasive surgical treatment of vanishing lung syndrome

Vanishing lung syndrome is a rare disease that could be treated successfully in selected cases with bullectomy. Protective ventilation is very important during surgery to achieve optimal post-operative results and to prevent complications. Hypercapnia and respiratory acidosis are the main disadvantages of this ventilator strategy. The use of extracorporeal CO₂ removal device has been introduced to support protective and ultra-protective ventilation during respiratory failure in complex cases. In thoracic surgery the intraoperative use of this device is still not widespread. We report a successful case of a giant left lung bullectomy with intraoperative support with Pro-Lung CO₂ removal device for the management of hypercapnia during single lung ventilation.

Spontaneous breathing in patients with severe acute respiratory distress syndrome receiving prolonged extracorporeal membrane oxygenation

Background

The use of extracorporeal membrane oxygenation (ECMO) in awake, spontaneously breathing and non-intubated patients (awake ECMO) may be a novel therapeutic strategy for severe acute respiratory distress syndrome (ARDS) patients. The purpose of this study is to assess the feasibility and safety of awake ECMO in severe ARDS patients receiving prolonged ECMO (> 14 days).

Methods

We describe our experience with 12 consecutive severe ARDS patients (age, 39.1 ± 16.4 years) supported with awake ECMO to wait for native lung recovery during prolonged ECMO treatment from July 2013 to January 2018. Outcomes are reported including the hospital mortality, ECMO-related complications and physiological data on weaning from invasive ventilation.

Results

The patients received median 26.0 (15.5, 64.8) days of total ECMO duration in the cohort. The longest ECMO support duration was 121 days. Awake ECMO and extubation was implemented after median 10.2(5.0, 42.9) days of ECMO. Awake ECMO was not associated with increased morbidity. The total invasive ventilation duration, lengths of stay in the ICU and hospital in the cohort were 14.0(12.0, 37.3) days, 33.0(22.3, 56.5) days and 46.5(27.3, 84.8) days, respectively. The hospital mortality rate was 33.3% (4/12) in the cohort. Survivors had more stable respiratory rate and heart rate after extubation when compared to the non-survivors.

Conclusions

With carefully selected patients, awake ECMO is a feasible and safe strategy for severe pulmonary ARDS patients receiving prolonged ECMO support to wait for native lung recovery.

Low-flow assessment of current ECMO/ECCO2R rotary blood pumps and the potential effect on hemocompatibility

Background

Extracorporeal carbon dioxide removal (ECCO₂R) uses an extracorporeal circuit to directly remove carbon dioxide from the blood either in lieu of mechanical ventilation or in combination with it. While the potential benefits of the technology are leading to increasing use, there are very real risks associated with it. Several studies demonstrated major bleeding and clotting complications, often associated with hemolysis and poorer outcomes in patients receiving ECCO₂R. A better understanding of the risks originating specifically from the rotary blood pump component of the circuit is urgently needed.

Methods

High-resolution computational fluid dynamics was used to calculate the hemodynamics and hemocompatibility of three current rotary blood pumps for various pump flow rates.

Results

The hydraulic efficiency dramatically decreases to 5–10% if operating at blood flow rates below 1 L/min, the pump internal flow recirculation rate increases 6–12-fold in these flow ranges, and adverse effects are increased due to multiple exposures to high shear stress. The deleterious consequences include a steep increase in hemolysis and destruction of platelets.

Conclusions

The role of blood pumps in contributing to adverse effects at the lower blood flow rates used during ECCO₂R is shown here to be significant. Current rotary blood pumps should be used with caution if operated at blood flow rates below 2 L/min, because of significant and high recirculation, shear stress, and hemolysis. There is a clear and urgent need to design dedicated blood pumps which are optimized for blood flow rates in the range of 0.5–1.5 L/min.

Ethical Considerations for Mechanical Support

Extracorporeal life support can support patients with severe forms of cardiac and respiratory failure. Uncertainty remains about its optimal use owing in large part to its resource-intensive nature and the high acuity illness in supported patients. Specific issues include the identification of patients most likely to benefit, the appropriate duration of support when prognosis is uncertain, and what to do when patients become dependent on extracorporeal life support but no longer have hope for recovery or transplantation. Careful deliberation of ethical principles and potential dilemmas should be made when considering the use of extracorporeal life support in advanced cardiopulmonary failure.

A CO2 removal system using extracorporeal lung and renal assist device with an acid and alkaline infusion

The patients with respiratory failure need high tidal volume by mechanical ventilation, which lead to the ventilator-induced lung injury. We developed an extracorporeal lung and renal assist device (ELRAD), comprising acid infusion, membrane lung, continuous hemodiafiltration and alkaline infusion. To evaluate this system, we conducted in vivo studies using experimental swine which were connected to the new system. In vivo experiments consist of four protocols; baseline = hemodiafiltration only (no O₂ gas flow to membrane lung); membrane lung = "Baseline" plus O₂ gas flow to membrane lung; "Acid infusion" = "Membrane lung" plus continuous acid infusion; ELRAD = "Acid infusion" plus continuous alkaline infusion. We changed the ventilatory rate of the mechanical ventilation to maintain PCO₂ at 50-55 mmHg during the four protocols. The results showed that there was statistically no significant difference in the levels of pH, HCO₃^-, and base excess when each study protocol was initiated. The amount of CO₂ eliminated by the membrane lung significantly increased by 1.6 times in the acid infusion protocol and the ELRAD protocol compared to the conventional membrane lung protocol. Minute ventilation in the ELRAD protocol significantly decreased by 0.5 times compared with the hemodiafiltration only protocol (P < 0.0001), the membrane lung (P = 0.0006) and acid infusion protocol (P = 0.0017), respectively. In conclusion, a developed CO₂ removal system efficiently removed CO₂ at low blood flow and reduced minute ventilation, while maintaining acid-base balance within the normal range.

A 2-year multicenter, observational, prospective, cohort study on extracorporeal CO2 removal in a large metropolis area

Background

Extracorporeal carbon dioxide removal (ECCO₂R) is a promising technique for the management of acute respiratory failure, but with a limited level of evidence to support its use outside clinical trials and/or data collection initiatives. We report a collaborative initiative in a large metropolis.

Methods

To assess on a structural basis the rate of utilization as well as efficacy and safety parameters of 2 ECCO₂R devices in 10 intensive care units (ICU) during a 2-year period.

Results

Seventy patients were recruited in 10 voluntary and specifically trained centers. The median utilization rate was 0.19 patient/month/center (min 0.04; max 1.20). ECCO₂R was started under invasive mechanical ventilation (IMV) in 59 patients and non-invasive ventilation in 11 patients. The Hemolung Respiratory Assist System (Alung) was used in 53 patients and the iLA Activve iLA kit (Xenios Novalung) in 17 patients. Main indications were ultraprotective ventilation for ARDS patients (n = 24), shortening the duration of IMV in COPD patients (n = 21), preventing intubation in COPD patients (n = 9), and controlling hypercapnia and dynamic hyperinflation in mechanically ventilated patients with severe acute asthma (n = 6). A reduction in median V_T was observed in ARDS patients from 5.9 to 4.1 ml/kg (p <0.001). A reduction in PaCO₂ values was observed in AE-COPD patients from 67.5 to 51 mmHg (p< 0.001). Median duration of ECCO₂R was 5 days (IQR 3–8). Reasons for ECCO₂R discontinuation were improvement (n = 33), ECCO₂R-related complications (n = 18), limitation of life-sustaining therapies or measures decision (n = 10), and death (n = 9). Main adverse events were hemolysis (n = 21), bleeding (n = 17), and lung membrane clotting (n = 11), with different profiles between the devices. Thirty-five deaths occurred during the ICU stay, 3 of which being ECCO₂R-related.

Conclusions

Based on a registry, we report a low rate of ECCO₂R device utilization, mainly in severe COPD and ARDS patients. Physiological efficacy was confirmed in these two populations. We confirmed safety concerns such as hemolysis, bleeding, and thrombosis, with different profiles between the devices. Such results could help to design future studies aiming to enhance safety, to demonstrate a still-lacking strong clinical benefit of ECCO₂R, and to guide the choice between different devices.

Trial registration

ClinicalTrials.gov: Identifier: NCT02965079 retrospectively registered https://clinicaltrials.gov/ct2/show/NCT02965079

Extracorporeal Life Support for Adults With Respiratory Failure and Related Indications: A Review

IMPORTANCE

The substantial growth over the last decade in the use of extracorporeal life support for adults with acute respiratory failure reveals an enthusiasm for the technology not always consistent with the evidence. However, recent high-quality data, primarily in patients with acute respiratory distress syndrome, have made extracorporeal life support more widely accepted in clinical practice.

OBSERVATIONS

Clinical trials of extracorporeal life support for acute respiratory failure in adults in the 1970s and 1990s failed to demonstrate benefit, reducing use of the intervention for decades and relegating it to a small number of centers. Nonetheless, technological improvements in extracorporeal support made it safer to use. Interest in extracorporeal life support increased with the confluence of 2 events in 2009: (1) the publication of a randomized clinical trial of extracorporeal life support for acute respiratory failure and (2) the use of extracorporeal life support in patients with severe acute respiratory distress syndrome during the influenza A(H1N1) pandemic. In 2018, a randomized clinical trial in patients with very severe acute respiratory distress syndrome demonstrated a seemingly large decrease in mortality from 46% to 35%, but this difference was not statistically significant. However, a Bayesian post hoc analysis of this trial and a subsequent meta-analysis together suggested that extracorporeal life support was beneficial for patients with very severe acute respiratory distress syndrome. As the evidence supporting the use of extracorporeal life support increases, its indications are expanding to being a bridge to lung transplantation and the management of patients with pulmonary vascular disease who have right-sided heart failure. Extracorporeal life support is now an acceptable form of organ support in clinical practice.

CONCLUSIONS AND RELEVANCE

The role of extracorporeal life support in the management of adults with acute respiratory failure is being redefined by advances in technology and increasing evidence of its effectiveness. Future developments in the field will result from technological advances, an increased understanding of the physiology and biology of extracorporeal support, and increased knowledge of how it might benefit the treatment of a variety of clinical conditions.

Independent lung ventilation: Implementation strategies and review of literature

Independent lung ventilation, though infrequently used in the critical care setting, has been reported as a rescue strategy for patients in respiratory failure resulting from severe unilateral lung pathology. This involves isolating and ventilating the right and left lung differently, using separate ventilators. Here, we describe our experience with independent lung ventilation in a patient with unilateral diffuse alveolar hemorrhage, who presented with severe hypoxemic respiratory failure despite maximal ventilatory support. Conventional ventilation in this scenario leads to preferential distribution of tidal volume to the non-diseased lung causing over distension and inadvertent volume trauma. Since each lung has a different compliance and respiratory mechanics, instituting separate ventilation strategies to each lung could potentially minimize lung injury. Based on review of literature, we provide a detailed description of indications and procedures for establishing independent lung ventilation, and also provide an algorithm for management and weaning a patient from independent lung ventilation.

Extracorporeal carbon dioxide removal for lowering the risk of mechanical ventilation: research questions and clinical potential for the future

As a result of technical improvements, extracorporeal carbon dioxide removal (ECCO₂R) now has the potential to play an important role in the management of adults with acute respiratory failure. There is growing interest in the use of ECCO₂R for the management of both hypoxaemic and hypercapnic respiratory failure. However, evidence to support its use is scarce and several questions remain about the best way to implement this therapy, which can be associated with serious side-effects. This Review reflects the consensus opinion of an international group of clinician scientists with expertise in managing acute respiratory failure and in using ECCO₂R therapies in this setting. We concisely review clinically relevant aspects of ECCO₂R, and provide a series of recommendations for clinical practice and future research, covering topics that include the practicalities of ECCO₂R delivery, indications for use, and service delivery.

Extracorporeal carbon dioxide removal for acute hypercapnic respiratory failure

In the past, the only treatment of acute exacerbations of obstructive diseases with hypercapnic respiratory failure refractory to medical treatment was invasive mechanical ventilation (IMV). Considerable technical improvements transformed extracorporeal techniques for carbon dioxide removal in an attractive option to avoid worsening respiratory failure and respiratory acidosis, and to potentially prevent or shorten the duration of IMV in patients with exacerbation of COPD and asthma. In this review, we will present a summary of the pathophysiological rationale and evidence of ECCO₂R in patients with severe exacerbations of these pathologies.

Control of respiratory drive by extracorporeal CO2 removal in acute exacerbation of COPD breathing on non-invasive NAVA

Background

Veno-venous extracorporeal CO₂ removal (vv-ECCO₂R) and non-invasive neurally adjusted ventilator assist (NIV-NAVA) are two promising techniques which may prevent complications related to prolonged invasive mechanical ventilation in patients with acute exacerbation of COPD.

Methods

A physiological study of the electrical activity of the diaphragm (Edi) response was conducted with varying degrees of extracorporeal CO₂ removal to control the respiratory drive in patients with severe acute exacerbation of COPD breathing on NIV-NAVA.

Results

Twenty COPD patients (SAPS II 37 ± 5.6, age 57 ± 9 years) treated with vv-ECCO₂R and supported by NIV-NAVA were studied during stepwise weaning of vv-ECCO₂R. Based on dyspnea, tolerance, and blood gases, weaning from vv-ECCO₂R was successful in 12 and failed in eight patients. Respiratory drive (measured via the Edi) increased to 19 ± 10 μV vs. 56 ± 20 μV in the successful and unsuccessful weaning groups, respectively, resulting in all patients keeping their CO₂ and pH values stable. Edi was the best predictor for vv-ECCO₂R weaning failure (ROC analysis AUC 0.95), whereas respiratory rate, rapid shallow breathing index, and tidal volume had lower predictive values. Eventually, 19 patients were discharged home, while one patient died. Mortality at 90 days and 180 days was 15 and 25%, respectively.

Conclusions

This study demonstrates for the first time the usefulness of the Edi signal to monitor and guide patients with severe acute exacerbation of COPD on vv-ECCO₂R and NIV-NAVA. The Edi during vv-ECCO₂R weaning was found to be the best predictor of tolerance to removing vv-ECCO₂R.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2404-y) contains supplementary material, which is available to authorized users.

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.

[Indications and limitations of ECMO therapy : Considerations on evidence, treatment decisions and ethical challenges]

The present work sheds light on the possibilities and limitations of modern extracorporeal membrane oxygenation (ECMO) therapy in the case of heart or lung failure. Since the number of applications of extracorporeal lung and heart/lung replacement procedures has increased dramatically in the last few years in severely ill patients, decision-making for a meaningful indication and in the course of a possible therapy target change has become particularly difficult, especially with regard to the complex situation in organ transplantation in Germany. An attempt is made to elucidate the dilemma between data from large controlled trials and epidemiological studies and the patients' individuality.