Intermittent extracorporeal CO2 removal in chronic obstructive pulmonary disease patients: a fiction or an option

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 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 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.

Dual Carbon Dioxide Capture to Achieve Highly Efficient Ultra-Low Blood Flow Extracorporeal Carbon Dioxide Removal

Extracorporeal CO₂ removal is a highly promising support therapy for patients with hypercapnic respiratory failure but whose clinical implementation and patient benefit is hampered by high cost and highly specialized expertise required for safe use. Current approaches target removal of the gaseous CO₂ dissolved in blood which limits their ease of clinical use as high blood flow rates are required to achieve physiologically significant CO₂ clearance. Here, a novel hybrid approach in which a zero-bicarbonate dialysis is used to target removal of bicarbonate ion coupled to a gas exchange device to clear dissolved CO₂, achieves highly efficiently total CO₂ capture while maintaining systemic acid-base balance. In a porcine model of acute hypercapnic respiratory failure, a CO₂-reduction of 61.4 ± 14.4 mL/min was achieved at a blood flow rate of 248 mL/min using pediatric-scale priming volumes. The dialyzer accounted for 81% of total CO₂ capture with an efficiency of 33% with a minimal pH change across the entire circuit. This study demonstrates the feasibility of a novel hybrid CO₂ capture approach capable of achieving physiologically significant CO₂ removal at ultralow blood flow rates with low priming volumes while leveraging widely available dialysis platforms to enable clinical adoption.

ECCO2R as a bridge to a decision in type II respiratory failure

Introduction

End-of-life decisions are often time consuming and difficult for everyone involved. In some of these cases extracorporeal life support systems could potentially be used not only as a bridge to treatment but as a tool to buy time to allow patient's participation in decision making and to avoid further futile invasive procedures.

Case report

A previously healthy 53-year-old female patient presented with respiratory failure of unknown cause. In the course of treatment her condition was deemed irreversible and the only option for any chance of long-term survival was a lung transplant. During this whole time the patient's condition was managed with extracorporeal carbon dioxide removal system (ECCO₂R). She remained compos mentis and expressed the wish to stop all the treatment as the option of lung transplant was not acceptable to her. Treatment was withdrawn and she passed away.

Discussion

In cases of end-of-life decisions, time can play an essential role. Even though extracorporeal life support systems have been conceptualised to be a bridge to treatment, they could be beneficial in a situation when time is needed to make a decision. ECCO₂R has been used as a treatment method in different settings, however, in this case it served as a tool to maintain the patient alive and conscious for a sufficient time for her to participate in decision making.

Conclusions

Our case report demonstrated that ECCO₂R could serve as a bridge to decision in situations when time is limited and the decisions that need to be made are difficult.