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

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).

Evaluation of CO2 removal rate of ECCO2R for a renal replacement therapy platform in an experimental setting

BACKGROUND

A critical parameter of extracorporeal CO2 removal (ECCO2R) applications is the CO2 removal rate (VCO2). Low-flow venovenous extracorporeal support with large-size membrane lung remains undefined. This study aimed to evaluate the VCO2 of a low-flow ECCO2R with large-size membrane lung using a renal replacement therapy platform in an experimental animal model.

METHODS

Twelve healthy pigs were placed under mechanical ventilation and connected to an ECCO2R-CRRT system (surface area = 1.8 m2; OMNIset®, BBraun, Germany). Respiratory settings were reduced to induce two degrees of hypercapnia. VCO2 was recorded under different combinations of PaCO2 (50-69 or 70-89 mm Hg), extracorporeal blood flow (ECBF; 200 or 350 mL/min), and gas flow (4, 6, or 10 L/min).

RESULTS

VCO2 increased with ECBF at all three gas flow rates. In severe hypercapnia, the increase in sweep gas flow from 4 to 10 L/min increased VCO2 from 86.38 ± 7.08 to 96.50 ± 8.71 mL/min at an ECBF of 350 mL/min, whereas at ECBF of 200 mL/min, any increase was less effective. But in mild hypercapnia, the increase in sweep gas flow result in significantly increased VCO2 at two ECBF. VCO2 increased with PaCO2 from 50-69 to 70-89 mm Hg at an ECBF of 350 mL/min, but not at ECBF of 200 mL/min. Post-membrane lung PCO2 levels were similar for different levels of premembrane lung PCO2 (p = 0.08), highlighting the gas exchange diffusion efficacy of the membrane lung in gas exchange diffusion. In severe hypercapnia, the reduction of PaCO2 elevated from 11.5% to 19.6% with ECBF increase only at a high gas flow of 10 L/min (p < 0.05) and increase of gas flow significantly reduced PaCO2 only at a high ECBF of 350 mL/min (p < 0.05).

CONCLUSIONS

Low-flow venovenous extracorporeal ECCO2R-CRRT with large-size membrane lung is more efficient with the increase of ECBF, sweep gas flow rate, and the degree of hypercapnia. The influence of sweep gas flow on VCO2 depends on the ECBF and degree of hypercapnia. Higher ECBF and gas flow should be chosen to reverse severe 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).

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).

Enhanced extracorporeal carbon dioxide removal by acidification and metabolic control

BACKGROUND

Extracorporeal carbon dioxide removal (ECCO2R) promotes protective ventilation in patients with acute respiratory failure, but devices with high CO2 extraction capacity are required for clinically relevant impact. This study evaluates three novel low-flow techniques based on dialysate acidification, also combined with renal replacement therapy, and metabolic control.

METHODS

Eight swine were connected to a low-flow (350 mL/min) extracorporeal circuit including a dialyzer with a closed-loop dialysate circuit, and two membrane lungs on blood (MLb) and dialysate (MLd), respectively. The following 2-hour steps were performed: 1) MLb-start (MLb ventilated); 2) MLbd-start (MLb and MLd ventilated); 3) HLac (lactic acid infusion before MLd); 4) HCl-NaLac (hydrochloric acid infusion before MLd combined with renal replacement therapy and reinfusion of sodium lactate); 5) HCl-βHB-NaLac (hydrochloric acid infusion before MLd combined with renal replacement therapy and reinfusion of sodium lactate and sodium 3-hydroxybutyrate). Caloric and fluid inputs, temperature, blood glucose and arterial carbon dioxide pressure were kept constant.

RESULTS

The total MLs CO2 removal in HLac (130±25 mL/min), HCl-NaLac (130±21 mL/min) and HCl-βHB-NaLac (124±18 mL/min) were higher compared with MLbd-start (81±15 mL/min, P<0.05) and MLb-start (55±7 mL/min, P<0.05). Minute ventilation in HLac (4.3±0.9 L/min), HCl-NaLac (3.6±0.8 L/min) and HCl-βHB-NaLac (3.6±0.8 L/min) were lower compared to MLb-start (6.2±1.1 L/min, P<0.05) and MLbd-start (5.8±2.1 L/min, P<0.05). Arterial pH was 7.40±0.03 at MLb-start and decreased only during HCl-βHB-NaLac (7.35±0.03, P<0.05). No relevant changes in electrolyte concentrations, hemodynamics and significant adverse events were detected.

CONCLUSIONS

The three techniques achieved a significant extracorporeal CO2 removal allowing a relevant reduction in minute ventilation with a sufficient safety profile.

Evaluation of the safety and efficacy of extracorporeal carbon dioxide removal in the critically ill using the PrismaLung+ device

BACKGROUND

Several extracorporeal carbon dioxide removal (ECCO2R) devices are currently in use with variable efficacy and safety profiles. PrismaLung+ is an ECCO2R device that was recently introduced into clinical practice. It is a minimally invasive, low flow device that provides partial respiratory support with or without renal replacement therapy. Our aim was to describe the clinical characteristics, efficacy, and safety of PrismaLung+ in patients with acute hypercapnic respiratory failure.

METHODS

All adult patients who required ECCO2R with PrismaLung+ for hypercapnic respiratory failure in our intensive care unit (ICU) during a 6-month period between March and September 2022 were included.

RESULTS

Ten patients were included. The median age was 55.5 (IQR 41-68) years, with 8 (80%) male patients. Six patients had acute respiratory distress syndrome (ARDS), and two patients each had exacerbations of asthma and chronic obstructive pulmonary disease (COPD). All patients were receiving invasive mechanical ventilation at the time of initiation of ECCO2R. The median duration of ECCO2R was 71 h (IQR 57-219). A significant improvement in pH and PaCO2 was noted within 30 min of initiation of ECCO2R. Nine patients (90%) survived to weaning of ECCO2R, eight (80%) survived to ICU discharge and seven (70%) survived to hospital discharge. The median duration of ICU and hospital stays were 14.5 (IQR 8-30) and 17 (IQR 11-38) days, respectively. There were no patient-related complications with the use of ECCO2R. A total of 18 circuits were used in ten patients (median 2 per patient; IQR 1-2). Circuit thrombosis was noted in five circuits (28%) prior to reaching the expected circuit life with no adverse clinical consequences.

CONCLUSION(S)

PrismaLung+ rapidly improved PaCO2 and pH with a good clinical safety profile. Circuit thrombosis was the only complication. This data provides insight into the safety and efficacy of PrismaLung+ that could be useful for centres aspiring to introduce ECCO2R into their clinical practice.

Ultraprotective Ventilation via ECCO2R in Three Patients Presenting an Air Leak: Is ECCO2R Effective?

Extracorporeal CO₂ removal (ECCO2R) is a therapeutic approach that allows protective ventilation in acute respiratory failure by preventing hypercapnia and subsequent acidosis. The main indications for ECCO2R in acute respiratory failure are COPD (chronic obstructive pulmonary disease) exacerbation, acute respiratory distress syndrome (ARDS) and other situations of asthmatics status. However, CO₂ removal procedure is not extended to those ARDS patients presenting an air leak. Here, we report three cases of air leaks in patients with an ARDS that were successfully treated using a new ECCO2R device. Case 1 is a polytrauma patient that developed pneumothorax during the hospital stay, case 2 is a patient with a post-surgical bronchial fistula after an Ivor-Lewis esophagectomy, and case 3 is a COVID-19 patient who developed a spontaneous pneumothorax after being hospitalized for a prolonged time. ECCO2R allowed for protective ventilation mitigating VILI (ventilation-induced lung injury) and significantly improved hypercapnia and respiratory acidemia, allowing time for the native lung to heal. Although further investigation is needed, our observations seem to suggest that CO₂ removal can be a safe and effective procedure in patients connected to mechanical ventilation with ARDS-associated air leaks.

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.