Is Extracorporeal CO2 Removal Really “Safe” and “Less” Invasive? Observation of Blood Injury and Coagulation Impairment during ECCO2R

First 24-Hour-Long Intensive Care Unit Testing of a Clinical-Scale Microfluidic Oxygenator in Swine: A Safety and Feasibility Study

Microfluidic membrane oxygenators are designed to mimic branching vasculature of the native lung during extracorporeal lung support. To date, scaling of such devices to achieve clinically relevant blood flow and lung support has been a limitation. We evaluated a novel multilayer microfluidic blood oxygenator (BLOx) capable of supporting 750-800 ml/min blood flow versus a standard hollow fiber membrane oxygenator (HFMO) in vivo during veno-venous extracorporeal life support for 24 hours in anesthetized, mechanically ventilated uninjured swine (n = 3/group). The objective was to assess feasibility, safety, and biocompatibility. Circuits remained patent and operated with stable pressures throughout 24 hours. No group differences in vital signs or evidence of end-organ damage occurred. No change in plasma free hemoglobin and von Willebrand factor multimer size distribution were observed. Platelet count decreased in BLOx at 6 hours (37% dec, P = 0.03), but not in HFMO; however, thrombin generation potential was elevated in HFMO (596 ± 81 nM·min) versus BLOx (323 ± 39 nM·min) at 24 hours ( P = 0.04). Other coagulation and inflammatory mediator results were unremarkable. BLOx required higher mechanical ventilator settings and showed lower gas transfer efficiency versus HFMO, but the stable device performance indicates that this technology is ready for further performance scaling and testing in lung injury models and during longer use conditions.

Extracorporeal Carbon Dioxide Removal to De-escalate Venovenous Extracorporeal Membrane Oxygenation in Severe COVID-19 Acute Respiratory Distress Syndrome

OBJECTIVES

In a subset of patients with COVID-19 acute respiratory distress syndrome (ARDS), there is a need for extracorporeal membrane oxygenation (ECMO) for pulmonary support. The primary extracorporeal support tool for severe COVID-19 ARDS is venovenous (VV) ECMO; however, after hypoxemic respiratory failure resolves, many patients experience refractory residual hypercarbic respiratory failure. Extracorporeal carbon dioxide removal (ECCO2R) for isolated hypercarbic type II respiratory failure can be used in select cases to deescalate patients from VV ECMO while the lung recovers the ability to exchange CO2. The objective of this study was to describe the authors' experience in using ECCO2R as a bridge from VV ECMO.

DESIGN

Hemolung Respiratory Assist System (RAS) is a commercially available (ECCO2R) device, and the United States Food and Drug Administration accelerated its use under its Emergency Use Authorization for the treatment of refractory hypercarbic respiratory failure in COVID-19-induced ARDS. This created an environment in which selected and targeted mechanical circulatory support therapy for refractory hypercarbic respiratory failure could be addressed. This retrospective study describes the application of Hemolung RAS as a VV ECMO deescalation platform to treat refractory hypercarbic respiratory failure after the resolution of hypoxemic COVID-19 ARDS.

SETTING

A quaternary-care academic medical center, single institution.

PARTICIPANTS

Patients with refractory hypercarbic respiratory failure after COVID-19 ARDS who were previously supported with VV ECMO.

MEASUREMENTS AND MAIN RESULTS

Twenty-one patients were placed on ECCO2R after VV ECMO for COVID-19 ARDS. Seventeen patients successfully were transitioned to ECCO2R and then decannulated; 3 patients required reescalation to VV ECMO secondary to hypercapnic respiratory failure, and 1 patient died while on ECCO2R. Five (23.8%) of the 21 patients were transitioned off of VV ECMO to ECCO2R, with a compliance of <20 (mL/cmH2O). Of these patients, 3 with low compliance were reescalated to VV ECMO.

CONCLUSIONS

Extracorporeal carbon dioxide removal can be used to continue supportive methods for patients with refractory type 2 hypercarbic respiratory failure after COVID-19 ARDS for patients previously on VV ECMO. Patients with low compliance have a higher rate of reescalation to VV ECMO.

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.

Comparison of Hemostatic Changes in Pump-driven Extracorporeal Carbon Dioxide Removal and Venovenous Extracorporeal Membrane Oxygenation

Extracorporeal carbon dioxide removal (ECCO 2 R) has gained widespread use as a supposedly less invasive alternative for hypercapnic respiratory failure besides venovenous extracorporeal membrane oxygenation (VV ECMO). Despite technological advances, coagulation-related adverse events remain a major challenge in both therapies. The overlapping operating areas of VV ECMO and pump-driven ECCO 2 R could allow for a device selection targeted at the lowest risk of such complications. This retrospective analysis of 47 consecutive patients compared hemostatic changes between pump-driven ECCO 2 R (n = 23) and VV ECMO (n = 24) by application of linear mixed effect models. A significant decrease in platelet count, increase in D-dimer levels, and decrease of fibrinogen levels were observed. However, except for fibrinogen, the type of extracorporeal support did not have a significant effect on the time course of these parameters. Our findings suggest that in terms of hemocompatibility, pump-driven ECCO 2 R is not significantly different from VV ECMO.

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.

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.

Acquired von Willebrand syndrome in paediatric patients during mechanical circulatory support

OBJECTIVES

Bleeding signs can become life-threatening complications in patients on mechanical circulatory support (MCS). Clinical phenotyping and comprehensive analyses of the cause of bleeding are, therefore, essential, especially when risk-stratifying patients during MCS workup. We conducted coagulation analyses and determined von Willebrand factor (VWF) parameters in a paediatric cohort on temporary extracorporeal life support, extracorporeal membrane oxygenation or long-term ventricular assist device support.

METHODS

We carried out an observational single-centre study including 30 children with MCS (extracorporeal life support, n = 13; extracorporeal membrane oxygenation, n = 5; and ventricular assist device, n = 12). We also assessed the acquired von Willebrand parameters of each study participant: collagen binding capacity (VWF:CB), the ratio of collagen-binding capacity to VWF antigen (VWF:CB/VWF:Ag) and high-molecular-weight VWF multimers. We also documented bleeding events, transfusion requirement, haemolysis parameters and surgical interventions.

RESULTS

All children developed AVWS (acquired von Willebrand syndrome) during MCS, usually during the early postoperative course. They presented no AVWS after device explantation. We detected a loss of high-molecular-weight VWF multimers, decreased VWF:CB/VWF:Ag ratios and reduced VWF:CB levels. Twenty of the 30 patients experienced bleeding complications; approximately 53% of them required surgical revision. There were no deaths due to bleeding during support.

CONCLUSIONS

The AVWS prevalence in paediatric patients on MCS is 100% regardless of the types of devices tested in this study. The bleeding propensity of AVWS patients widely varies.

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.

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.

Bleeding and Thrombosis With Pediatric Extracorporeal Life Support: A Roadmap for Management, Research, and the Future From the Pediatric Cardiac Intensive Care Society: Part 2

OBJECTIVES

To make recommendations on improving understanding of bleeding and thrombosis with pediatric extracorporeal life support including future research directions.

DATA SOURCES

Evaluation of literature and consensus conferences of pediatric critical care and extracorporeal life support experts.

STUDY SELECTION

A team of 10 experts with pediatric cardiac and extracorporeal membrane oxygenation experience and expertise met through the Pediatric Cardiac Intensive Care Society to review current knowledge and make recommendations for future research to establish "best practice" for anticoagulation management related to extracorporeal life support.

DATA EXTRACTION/DATA SYNTHESIS

This white paper focuses on clinical understanding and limitations of current strategies to monitor anticoagulation. For each test of anticoagulation, limitations of current knowledge are addressed and future research directions suggested.

CONCLUSIONS

No consensus on best practice for anticoagulation monitoring exists. Structured scientific evaluation to answer questions regarding anticoagulation monitoring and bleeding and thrombotic events should occur in multicenter studies using standardized approaches and well-defined endpoints. Outcomes related to need for component change, blood product administration, healthcare outcome, and economic assessment should be incorporated into studies. All centers should report data on patient receiving extracorporeal life support to a registry.

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 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 CO2 removal and regional citrate anticoagulation in an experimental model of hypercapnic acidosis

Low flow extracorporeal veno-venous CO₂ removal (ECCO₂ R) therapy is used to remove CO₂ while reducing ventilation intensity. However, the use of this technique is limited because efficiency of CO₂ removal and potential beneficial effects on pulmonary hemodynamics are not precisely established. Moreover, this technique requires anticoagulation that may induce severe complications in critically ill patients. Therefore, our study aimed at determining precise efficiency of CO₂ extraction and its effects on right ventricular (RV) afterload, and comparing regional anticoagulation with citrate to systemic heparin anticoagulation during ECCO₂ R. This study was performed in an experimental model of severe hypercapnic acidosis performed in two groups of three pigs. In the first group (heparin group), pigs were anticoagulated with a standard protocol of unfractionated heparin while citrate was used for ECCO₂ R device anticoagulation in the second group (citrate group). After sedation, analgesia and endotracheal intubation, pigs were connected to a volume-cycled ventilator. Severe hypercapnic acidosis was obtained by reducing tidal volume by 60%. ECCO₂ R was started in both groups when arterial pH was lower than 7.2. Pump Assisted Lung Protection (PALP, Maquet, Rastatt, Germany) system was used to remove CO₂ . CO₂ extraction, arterial pH, PaCO₂ as well as systemic and pulmonary hemodynamic were continuously followed. Mean arterial pH was normalized to 7.37 ± 1.4 at an extracorporeal blood flow of 400 mL/min, coming from 7.11 ± 1.3. RV end-systolic pressure increased by over 30% during acute hypercapnic acidosis and was normalized in parallel with CO₂ removal. CO₂ extraction was not significantly increased in citrate group as compared to heparin group. Mean ionized calcium and MAP were significantly lower in the citrate group than in the heparin group during ECCO₂ R (1.03 ± 0.20 vs. 1.33 ± 0.19 and 57 ± 14 vs. 68 ± 15 mm Hg, respectively). ECCO₂ R was highly efficient to normalize pH and PaCO₂ and to reduce RV afterload resulting from hypercapnic acidosis. Regional anticoagulation with citrate solution was as effective as standard heparin anticoagulation but did not improve CO₂ removal and lead to more hypocalcemia and hypotension.

Effects of sodium citrate, citric acid and lactic acid on human blood coagulation

INTRODUCTION

Citric acid infusion in extracorporeal blood may allow concurrent regional anticoagulation and enhancement of extracorporeal CO₂ removal. Effects of citric acid on human blood thromboelastography and aggregometry have never been tested before.

METHODS

In this in vitro study, citric acid, sodium citrate and lactic acid were added to venous blood from seven healthy donors, obtaining concentrations of 9 mEq/L, 12 mEq/L and 15 mEq/L. We measured gas analyses, ionized calcium (iCa⁺⁺) concentration, activated clotting time (ACT), thromboelastography and multiplate aggregometry. Repeated measure analysis of variance was used to compare the acidifying and anticoagulant properties of the three compounds.

RESULTS

Sodium citrate did not affect the blood gas analysis. Increasing doses of citric and lactic acid progressively reduced pH and HCO₃^- and increased pCO₂ (p<0.001). Sodium citrate and citric acid similarly reduced iCa⁺⁺, from 0.39 (0.36-0.39) and 0.35 (0.33-0.36) mmol/L, respectively, at 9 mEq/L to 0.20 (0.20-0.21) and 0.21 (0.20-0.23) mmol/L at 15 mEq/L (p<0.001). Lactic acid did not affect iCa⁺⁺ (p=0.07). Sodium citrate and citric acid similarly incremented the ACT, from 234 (208-296) and 202 (178-238) sec, respectively, at 9 mEq/L, to >600 sec at 15 mEq/L (p<0.001). Lactic acid did not affect the ACT values (p=0.486). Sodium citrate and citric acid similarly incremented R-time and reduced α-angle and maximum amplitude (MA) (p<0.001), leading to flat-line thromboelastograms at 15 mEq/L. Platelet aggregometry was not altered by any of the three compounds.

CONCLUSIONS

Citric acid infusions determine acidification and anticoagulation of blood similar to lactic acid and sodium citrate, respectively.

Acquired von Willebrand syndrome and impaired platelet function during venovenous extracorporeal membrane oxygenation: Rapid onset and fast recovery

BACKGROUND

Bleeding contributes to the high mortality of venovenous extracorporeal membrane oxygenation (vvECMO). The development of acquired von Willebrand syndrome (AVWS) has been identified as relevant pathology during ECMO. This study was performed to determine the onset of AVWS after implantation and the recovery of von Willebrand factor (VWF) parameters after explantation of ECMO in a large cohort of patients.

METHODS

VWF parameters of 59 patients treated with vvECMO at a university ECMO center were obtained before ECMO implantation, during therapy, and after explantation. In a subgroup of patients, light transmission aggregometry of platelets and flow-cytometric quantification of platelet granule secretion were performed.

RESULTS

All patients developed severe AVWS hours after implantation of vvECMO. After explantation, AVWS recovered within 3 hours in 60%, within 6 hours in 86%, and in all patients within 1 day. Aggregometry showed hypoaggregability of platelets after stimulation with ADP, ristocetin, collagen, and epinephrine. Flow-cytometric platelet analyses revealed severely reduced expression of CD62 and CD63.

CONCLUSIONS

All patients during vvECMO support rapidly develop AVWS and platelet dysfunction, resulting in severe impairment of coagulation. After explantation, AVWS overwhelmingly recovers within hours, resulting in a hypercoagulative state. These findings augment the need for novel extracorporeal technologies with reduced shear stress, and shift the emphasis for intense anti-coagulation during ECMO instead to a time-point after explantation.

Extracorporeal carbon dioxide removal in acute exacerbations of chronic obstructive pulmonary disease

Extracorporeal carbon dioxide removal (ECCO2R) has been proposed as an adjunctive intervention to avoid worsening respiratory acidosis, thereby preventing or shortening the duration of invasive mechanical ventilation (IMV) in patients with exacerbation of chronic obstructive pulmonary disease (COPD). This review will present a comprehensive summary of the pathophysiological rationale and clinical evidence of ECCO2R in patients suffering from severe COPD exacerbations.

Low flow extracorporeal CO2 removal in ARDS patients: a prospective short-term crossover pilot study

Background

Lung protective mechanical ventilation (MV) is the corner stone of therapy for ARDS. However, its use may be limited by respiratory acidosis.

This study explored feasibility of, effectiveness and safety of low flow extracorporeal CO₂ removal (ECCO₂R).

Methods

This was a prospective pilot study, using the Abylcap® (Bellco) ECCO₂R, with crossover off-on-off design (2-h blocks) under stable MV settings, and follow up till end of ECCO₂R. Primary endpoint for effectiveness was a 20% reduction of PaCO₂ after the first 2-h. Adverse events (AE) were recorded prospectively.

We included 10 ARDS patients on MV, with PaO₂/FiO₂ < 150 mmHg, tidal volume ≤ 8 mL/kg with positive end-expiratory pressure ≥ 5 cmH₂O, FiO₂ titrated to SaO₂ 88–95%, plateau pressure ≥ 28 cmH₂O, and respiratory acidosis (pH <7.25).

Results

After 2-h of ECCO₂R, 6 patients had a ≥ 20% decrease in PaCO₂ (60%); PaCO₂ decreased 28.4% (from 58.4 to 48.7 mmHg, p = 0.005), and pH increased (1.59%, p = 0.005). ECCO₂R was hemodynamically well tolerated. During the whole period of ECCO₂R, 6 patients had an AE (60%); bleeding occurred in 5 patients (50%) and circuit thrombosis in 3 patients (30%), these were judged not to be life threatening.

Conclusions

In ARDS patients, low flow ECCO₂R significantly reduced PaCO₂ after 2 h, Follow up during the entire ECCO₂R period revealed a high incidence of bleeding and circuit thrombosis.

Trial registration

https://clinicaltrials.gov identifier: NCT01911533, registered 23 July 2013.

Electronic supplementary material

The online version of this article (10.1186/s12871-017-0445-9) contains supplementary material, which is available to authorized users.

[Extracorporeal lung support]

Systems for extracorporeal lung support have recently undergone significant technological improvements leading to more effective and safe treatment. Despite limited scientific evidence these systems are increasingly used in the intensive care unit for treatment of different types of acute respiratory failure. In general two types of systems can be differentiated: devices for extracorporeal carbon dioxide removal (ECCO₂R) for ventilatory insufficiency and devices for extracorporeal membrane oxygenation (ECMO) for severe hypoxemic failure. Despite of all technological developments extracorporeal lung support remains an invasive and a potentially dangerous form of treatment with bleeding and vascular injury being the two main complications. For this reason indications and contraindications should always be critically considered and extracorporeal lung support should only be carried out in centers with appropriate experience and expertise.