Utilization and outcomes of extracorporeal CO2 removal (ECCO2 R): Systematic review and meta-analysis of arterio-venous and veno-venous ECCO2 R approaches

INTRODUCTION

Extracorporeal carbon dioxide removal (ECCO₂ R) provides respiratory support to patients suffering from hypercapnic respiratory failure by utilizing an extracorporeal shunt and gas exchange membrane to remove CO₂ from either the venous (VV-ECCO₂ R) or arterial (AV-ECCO₂ R) system before return into the venous site. AV-ECCO₂ R relies on the patient's native cardiac function to generate pressures needed to deliver blood through the extracorporeal circuit. VV-ECCO₂ R utilizes a mechanical pump and can be used to treat patients with inadequate native cardiac function. We sought to evaluate the existing evidence comparing the subgroups of patients supported on VV and AV-ECCO₂ R devices.

METHODS

A literature search was performed to identify all relevant studies published between 2000 and 2019. Demographic information, medical indications, perioperative variables, and clinical outcomes were extracted for systematic review and meta-analysis.

RESULTS

Twenty-five studies including 826 patients were reviewed. 60% of patients (497/826) were supported on VV-ECCO₂ R. The most frequent indications were acute respiratory distress syndrome (ARDS) [69%, (95%CI: 53%-82%)] and chronic obstructive pulmonary disease (COPD) [49%, (95%CI: 37%-60%)]. ICU length of stay was significantly shorter in patients supported on VV-ECCO₂ R compared to AV-ECCO₂ R [15 (95%CI: 7-23) vs. 42 (95%CI: 17-67) days, p = 0.05]. In-hospital mortality was not significantly different [27% (95%CI: 18%-38%) vs. 36% (95%CI: 24%-51%), p = 0.26].

CONCLUSION

Both VV and AV-ECCO₂ R provided clinically meaningful CO₂ removal with comparable mortality.

Extracorporeal carbon dioxide Removal (ECCO2 R) with the Advanced Organ Support (ADVOS) system in critically ill COVID-19 patients

Disturbed oxygenation is foremost the leading clinical presentation in COVID‐19 patients. However, a small proportion also develop carbon dioxide removal problems. The Advanced Organ Support (ADVOS) therapy (ADVITOS GmbH, Munich, Germany) uses a less invasive approach by combining extracorporeal CO₂‐removal and multiple organ support for the liver and the kidneys in a single hemodialysis device. The aim of our study is to evaluate the ADVOS system as treatment option in‐COVID‐19 patients with multi‐organ failure and carbon dioxide removal problems. COVID‐19 patients suffering from severe respiratory insufficiency, receiving at least two treatments with the ADVOS multi system (ADVITOS GmbH, Munich, Germany), were eligible for study inclusion. Briefly, these included patients with acute kidney injury (AKI) according to KDIGO guidelines, and moderate or severe ARDS according to the Berlin definition, who were on invasive mechanical ventilation for more than 72 hours. In total, nine COVID‐19 patients (137 ADVOS treatment sessions with a median of 10 treatments per patient) with moderate to severe ARDS and carbon dioxide removal problems were analyzed. During the ADVOS treatments, a rapid correction of acid‐base balance and a continuous CO₂ removal could be observed. We observed a median continuous CO₂ removal of 49.2 mL/min (IQR: 26.9‐72.3 mL/min) with some treatments achieving up to 160 mL/min. The CO₂ removal significantly correlated with blood flow (Pearson 0.421; P < .001), PaCO₂ (0.341, P < .001) and HCO3‐ levels (0.568, P < .001) at the start of the treatment. The continuous treatment led to a significant reduction in PaCO₂ from baseline to the last ADVOS treatment. In conclusion, it was feasible to remove CO₂ using the ADVOS system in our cohort of COVID‐19 patients with acute respiratory distress syndrome and multiorgan failure. This efficient removal of CO₂ was achieved at blood flows up to 300 mL/min using a conventional hemodialysis catheter and without a membrane lung or a gas phase.

Comparison of Circular and Parallel-Plated Membrane Lungs for Extracorporeal Carbon Dioxide Elimination

Extracorporeal carbon dioxide removal (ECCO₂R) is an important technique to treat critical lung diseases such as exacerbated chronic obstructive pulmonary disease (COPD) and mild or moderate acute respiratory distress syndrome (ARDS). This study applies our previously presented ECCO₂R mock circuit to compare the CO₂ removal capacity of circular versus parallel-plated membrane lungs at different sweep gas flow rates (0.5, 2, 4, 6 L/min) and blood flow rates (0.3 L/min, 0.9 L/min). For both designs, two low-flow polypropylene membrane lungs (Medos Hilte 1000, Quadrox-i Neonatal) and two mid-flow polymethylpentene membrane lungs (Novalung Minilung, Quadrox-iD Pediatric) were compared. While the parallel-plated Quadrox-iD Pediatric achieved the overall highest CO₂ removal rates under medium and high sweep gas flow rates, the two circular membrane lungs performed relatively better at the lowest gas flow rate of 0.5 L/min. The low-flow Hilite 1000, although overall better than the Quadrox i-Neonatal, had the most significant advantage at a gas flow of 0.5 L/min. Moreover, the circular Minilung, despite being significantly less efficient than the Quadrox-iD Pediatric at medium and high sweep gas flow rates, did not show a significantly worse CO₂ removal rate at a gas flow of 0.5 L/min but rather a slight advantage. We suggest that circular membrane lungs have an advantage at low sweep gas flow rates due to reduced shunting as a result of their fiber orientation. Efficiency for such low gas flow scenarios might be relevant for possible future portable ECCO₂R devices.

Extracorporeal carbon dioxide removal in heart-beating donor with acute severe asthma: A case report

Status asthmaticus is a life-threatening disorder that can manifest in dangerous levels of hypercapnia and acidosis. The use of extracorporeal carbon dioxide removal (ECCO2R) has been used successfully to control pH and PaCO₂ in patients with acute severe asthma. The present report describes the use of this technology in near-fatal asthma with brain death, and awaiting organ harvest. The ProLUNG® system consists of a veno-venous hemoperfusion circuit with an artificial lung polymethylpentene membrane coated with phosphorylcholine with a surface of 1.81 m². The system can reach a blood flow of 450 ml/min trough a double-lumen central venous catheter (13.0 Fr) placed in femoral, subclavian or jugular vein. The platform is provided with automated management of airflow and VCO₂ monitoring during treatment. The patient was maintained on extracorporeal treatment ensuring stable arterial pH control and PaCO₂ control. In acute status asthmaticus, complicated with cardiac arrest, mini-invasive ECCO2R was an effective method of controlling pH and PaCO₂, for optimizing hemodynamic and aerobic metabolism and for performing protective ventilation for an optimal organ donor preservation until the organ harvest occurs.

Bench Validation of a Compact Low-Flow CO2 Removal Device

Background

There is increasing evidence demonstrating the value of partial extracorporeal CO₂ removal (ECCO₂R) for the treatment of hypercapnia in patients with acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. Mechanical ventilation has traditionally been used to treat hypercapnia in these patients, however, it has been well-established that aggressive ventilator settings can lead to ventilator-induced lung injury. ECCO₂R removes CO₂ independently of the lungs and has been used to permit lung protective ventilation to prevent ventilator-induced lung injury, prevent intubation, and aid in ventilator weaning. The Low-Flow Pittsburgh Ambulatory Lung (LF-PAL) is a low-flow ECCO₂R device that integrates the fiber bundle (0.65 m²) and centrifugal pump into a compact unit to permit patient ambulation.

Methods

A blood analog was used to evaluate the performance of the pump at various impeller rotation rates. In vitro CO₂ removal tested under normocapnic conditions and 6-h hemolysis testing were completed using bovine blood. Computational fluid dynamics and a mass-transfer model were also used to evaluate the performance of the LF-PAL.

Results

The integrated pump was able to generate flows up to 700 mL/min against the Hemolung 15.5 Fr dual lumen catheter. The maximum vCO₂ of 105 mL/min was achieved at a blood flow rate of 700 mL/min. The therapeutic index of hemolysis was 0.080 g/(100 min). The normalized index of hemolysis was 0.158 g/(100 L).

Conclusions

The LF-PAL met pumping, CO₂ removal, and hemolysis design targets and has the potential to enable ambulation while on ECCO₂R.

Extracorporeal CO2 removal by hemodialysis: in vitro model and feasibility

BACKGROUND

Critically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO₂ from the blood, mainly as bicarbonate. In this study, Stewart's approach to acid-base chemistry was used to create a dialysate that would maintain blood pH while removing CO₂ as well as determine the blood and dialysate flow rates necessary to remove clinically relevant CO₂ volumes.

METHODS

Bench studies were performed using a scaled down respiratory hemodialyzer in bovine or porcine blood. The scaling factor for the bench top experiments was 22.5. In vitro dialysate flow rates ranged from 2.2 to 24 mL/min (49.5-540 mL/min scaled up) and blood flow rates were set at 11 and 18.7 mL/min (248-421 mL/min scaled up). Blood inlet CO₂ concentrations were set at 50 and 100 mmHg.

RESULTS

Results are reported as scaled up values. The CO₂ removal rate was highest at intermittent hemodialysis blood and dialysate flow rates. At an inlet pCO₂ of 50 mmHg, the CO₂ removal rate increased from 62.6 ± 4.8 to 77.7 ± 3 mL/min when the blood flow rate increased from 248 to 421 mL/min. At an inlet pCO₂ of 100 mmHg, the device was able to remove up to 117.8 ± 3.8 mL/min of CO₂. None of the test conditions caused the blood pH to decrease, and increases were ≤0.08.

CONCLUSIONS

When the bench top data is scaled up, the system removes a therapeutic amount of CO₂ standard intermittent hemodialysis flow rates. The zero bicarbonate dialysate did not cause acidosis in the post-dialyzer blood. These results demonstrate that, with further development, respiratory hemodialysis can be a minimally invasive extracorporeal carbon dioxide removal treatment option.

Extracorporeal Support for Chronic Obstructive Pulmonary Disease: A Bright Future

In the past the only option for the treatment of respiratory failure due to acute exacerbation of chronic obstructive pulmonary disease (aeCOPD) was invasive mechanical ventilation. In recent decades, the potential for extracorporeal carbon dioxide (CO₂) removal has been realized. We review the various types of extracorporeal CO₂ removal, outline the optimal use of these therapies for aeCOPD, and make suggestions for future controlled trials. We also describe the advantages and requirements for an ideal long-term ambulatory CO₂ removal system for palliation of COPD.

Adverse effects of extracorporeal carbon dioxide removal (ECCO2R) for acute respiratory failure: a systematic review protocol

BACKGROUND

The extracorporeal membrane carbon dioxide removal (ECCO2R) system is primarily designed for the purpose of removing CO2 from the body for patients with potentially reversible severe acute hypercapnic respiratory failure or being considered for lung transplantation. Systematic reviews have focused on the effectiveness of ECCO2R. To the author's best knowledge, this is the first systematic review to focus on the adverse effects of this procedure.

METHODS

We will conduct a systematic review of procedure-related adverse effects of ECCO2R systems. A high sensitivity search strategy will be employed in Cochrane Library, MEDLINE, EMBASE, Web of Science and product regulatory databases and ongoing trial registers to identify citations. Reference lists of relevant studies and grey literature will also be searched. Screening of the results will be performed by two reviewers independently using pre-defined inclusion and exclusion criteria. Clinical trials and observational studies will be included. Data will be extracted using a purposefully developed extraction form. Appropriateness for statistical pooling of the results will be determined and carried out if heterogeneity is low to moderate. The GRADE framework will be employed to grade the overall quality of the evidence.

DISCUSSION

In the UK, the current access to the use of ECCO2R is possible only with special arrangements for clinical governance, consent and for audit or research. Current evidence on ECCO2R suggests that there are a number of well-recognised complications which vary greatly across studies. This systematic review will consolidate the existing knowledge on adverse effects resulting from the use of ECCO2R.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015023503 .