ECCO2R in 12 COVID-19 ARDS Patients With Extremely Low Compliance and Refractory Hypercapnia

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).

Venovenous extracorporeal membrane oxygenation for COVID-19 and influenza H1N1 associated acute respiratory distress syndrome: A comparative cohort study in China

Background

Venovenous extracorporeal membrane oxygenation (VV-ECMO) has been demonstrated to be effective in treating patients with virus-induced acute respiratory distress syndrome (ARDS). However, whether the management of ECMO is different in treating H1N1 influenza and coronavirus disease 2019 (COVID-19)-associated ARDS patients remains unknown.

Methods

This is a retrospective cohort study. We included 12 VV-ECMO-supported COVID-19 patients admitted to The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Eighth People's Hospital, and Wuhan Union Hospital West Campus between January 23 and March 31, 2020. We retrospectively included VV-ECMO-supported patients with COVID-19 and H1N1 influenza-associated ARDS. Clinical characteristics, respiratory mechanics including plateau pressure, driving pressure, mechanical power, ventilatory ratio (VR) and lung compliance, and outcomes were compared.

Results

Data from 25 patients with COVID-19 (n=12) and H1N1 (n=13) associated ARDS who had received ECMO support were analyzed. COVID-19 patients were older than H1N1 influenza patients (P=0.004). The partial pressure of arterial carbon dioxide (PaCO2) and VR before ECMO initiation were significantly higher in COVID-19 patients than in H1N1 influenza patients (P <0.001 and P=0.004, respectively). COVID-19 patients showed increased plateau and driving pressure compared with H1N1 subjects (P=0.013 and P=0.018, respectively). Patients with COVID-19 remained longer on ECMO support than did H1N1 influenza patients (P=0.015). COVID-19 patients who required ECMO support also had fewer intensive care unit and ventilator-free days than H1N1.

Conclusions

Compared with H1N1 influenza patients, COVID-19 patients were older and presented with increased PaCO2 and VR values before ECMO initiation. The differences between ARDS patients with COVID-19 and influenza on VV-ECMO detailed herein could be helpful for obtaining a better understanding of COVID-19 and for better clinical management.

[Recent research on extracorporeal carbon dioxide removal]

Extracorporeal carbon dioxide removal is an artificial lung auxiliary technique based on extrapulmonary gas exchange and can effectively remove carbon dioxide and provide oxygenation to a certain extent, and it is one of the effective treatment techniques for hypercapnia developed after mechanical ventilation and extracorporeal membrane oxygenation in recent years and has wide application prospect. This article elaborates on the development, working principle, advantages, classification, complications, and clinical application of extracorporeal carbon dioxide removal, so as to provide a new choice for extracorporeal carbon dioxide removal in clinical practice.

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 in acute hypoxaemic respiratory failure: a systematic review, Bayesian meta-analysis and trial sequential analysis

Purpose:

To assess the safety and efficacy of extracorporeal carbon dioxide removal (ECCO2R)versusstandard care in patients with acute hypoxaemic respiratory failure (AHRF).

Methods:

MEDLINE, Embase and clinical trial registries were searched from 1994 to 31 December 2021. We included randomised controlled trials (RCTs) and observational studies. Pairs of reviewers independently extracted data and assessed the risk of bias. The primary outcome was mortality. Secondary outcomes included ventilator-free days, length of stay, safety and adverse events and physiological changes. As a primary analysis, we performed a meta-analysis of mortality until day 30 using a Bayesian random effects model. We then performed a trial sequential analysis of RCTs.

Results:

21 studies met inclusion criteria: three RCTs, enrolling 531 patients, and 18 observational studies. In a pooled analysis of RCTs, the posterior probability of increased mortality with the use of ECCO2R was 73% (relative risk 1.19, 95% credible interval 0.70–2.29). There was substantial heterogeneity in the reporting of safety and adverse events. However, the incidence of extra and intracranial haemorrhage was higher (relative risk 3.00, 95% credible interval 0.41–20.51) among those randomised to ECCO2R. Current trials have accumulated 80.8% of the diversity-adjusted required information size and the lack of effect reaches futility for a 10% absolute risk reduction in mortality.

Conclusions:

The use of ECCO2R in patients with AHRF is not associated with improvements in clinical outcomes. Furthermore, it is likely that further trials of ECCO2R aiming to achieve an absolute risk reduction in mortality of ≥10% are futile.

The role of acute hypercapnia on mortality and short-term physiology in patients mechanically ventilated for ARDS: a systematic review and meta-analysis

Purpose

Hypercapnia is frequent during mechanical ventilation for acute respiratory distress syndrome (ARDS), but its effects on morbidity and mortality are still controversial. We conducted a systematic review and meta-analysis to explore clinical consequences of acute hypercapnia in adult patients ventilated for ARDS.

Methods

We searched Medline, Embase, and the Cochrane Library via the OVID platform for studies published from 1946 to 2021. “Permissive hypercapnia” defined hypercapnia in studies where the group with hypercapnia was ventilated with a protective ventilation (PV) strategy (lower V_T targeting 6 ml/kg predicted body weight) while the group without hypercapnia was managed with a non-protective ventilation (NPV); “imposed hypercapnia” defined hypercapnia in studies where hypercapnic and non-hypercapnic patients were managed with a similar ventilation strategy.

Results

Twenty-nine studies (10,101 patients) were included. Permissive hypercapnia, imposed hypercapnia under PV, and imposed hypercapnia under NPV were reported in 8, 21 and 1 study, respectively. Studies testing permissive hypercapnia reported lower mortality in hypercapnic patients receiving PV as compared to non-hypercapnic patients receiving NPV: OR = 0.26, 95% CI [0.07–0.89]. By contrast, studies reporting imposed hypercapnia under PV reported increased mortality in hypercapnic patients receiving PV as compared to non-hypercapnic patients also receiving PV: OR = 1.54, 95% CI [1.15–2.07]. There was a significant interaction between the mechanism of hypercapnia and the effect on mortality.

Conclusions

Clinical effects of hypercapnia are conflicting depending on its mechanism. Permissive hypercapnia was associated with improved mortality contrary to imposed hypercapnia under PV, suggesting a major role of PV strategy on the outcome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-022-06640-1.