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Alkaline Liquid Ventilation of the Membrane Lung for Extracorporeal Carbon Dioxide Removal (ECCO₂R): In Vitro Study.

ABSTRACT: Extracorporeal carbon dioxide removal (ECCO₂R) is a promising strategy to manage acute respiratory failure. We hypothesized that ECCO₂R could be enhanced by ventilating the membrane lung with a sodium hydroxide (NaOH) solution with high CO₂ absorbing capacity. A computed mathematical model was implemented to assess NaOH-CO₂ interactions. Subsequently, we compared NaOH infusion, named "alkaline liquid ventilation", to conventional oxygen sweeping flows. We built an extracorporeal circuit with two polypropylene membrane lungs, one to remove CO₂ and the other to maintain a constant PCO₂ (60 ± 2 mmHg). The circuit was primed with swine blood. Blood flow was 500 mL × min^-1. After testing the safety and feasibility of increasing concentrations of aqueous NaOH (up to 100 mmol × L^-1), the CO₂ removal capacity of sweeping oxygen was compared to that of 100 mmol × L^-1 NaOH. We performed six experiments to randomly test four sweep flows (100, 250, 500, 1000 mL × min^-1) for each fluid plus 10 L × min^-1 oxygen. Alkaline liquid ventilation proved to be feasible and safe. No damages or hemolysis were detected. NaOH showed higher CO₂ removal capacity compared to oxygen for flows up to 1 L × min^-1. However, the highest CO₂ extraction power exerted by NaOH was comparable to that of 10 L × min^-1 oxygen. Further studies with dedicated devices are required to exploit potential clinical applications of alkaline liquid ventilation.

SUBMITTER: Vivona L

PROVIDER: S-EPMC8306443 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Mechanical ventilation (MV) represents a lifesaving treatment for patients with respiratory failure, but it could be harmful through the development of ventilator-induced lung injury (VILI). In patients with acute respiratory distress syndrome (ARDS), protective MV strategies with low tidal volume to minimize VILI have been demonstrated to reduce lung injury and mortality. However, they can be limited by the emergence of uncontrolled hypercapnia. Similarly, in COPD patients, noninvasive MV failure often is associated with a progressive rise in arterial CO2 and need for endotracheal intubation, with higher risk of hospital mortality. Minimally invasive extracorporeal CO2 removal systems (ECCO2R) theoretically can remove the entire amount of the CO2 produced in the body per minute. In ARDS patients, ECCO2R may further reduce the risk of VILI ensuring ultraprotective MV and avoiding hypercapnia. In patients with exacerbation of COPD, ECCO2R may help to avoid intubation or facilitate weaning from invasive MV. In intensive care unit, concomitant renal and respiratory failure with MV is one of the strongest risk factors for hospital mortality. Combining ECCO2R and renal replacement therapy may support respiratory and renal functions and limit the side effects of MV. However, the need for systemic anticoagulation and the related risk of bleeding still represent a concern for a wider application of ECCO2R devices. In conclusion, ECCO2R is an effective support therapy to MV to limit its invasiveness and side effects, but its efficacy and safety must be proven in well-designed clinical trials. Objectives This chapter will:1 Explain the physiology of CO2 removal during extracorporeal support.2 Describe potential clinical applications of extracorporeal CO2 removal systems (ECCO2R) support therapy in patients with acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD) as well as in those with acute kidney injury requiring renal replacement therapy.

Project description:Background/aimTreatment of severe hypercapnic respiratory failure (HRF) has some challenges in patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS), especially when lung protective ventilation (LPV) strategies are required. Extracorporeal CO2 removal (ECCO2R) therapy is an emerging option to manage hypercapnia while allowing LPV in these cases. However, further data on ECCO2R use is still needed to make clear recommendations.Materials and methodsThis study was conducted on patients admitted to intensive care unit (ICU) between January 1st, 2016 to December 31st, 2019. The medical records were retrospectively scanned in institutional software database. Patients who received invasive mechanic ventilation (iMV) support due to severe HRF related to COPD or ARDS were included in the analyses. Patients were grouped according to treatment approaches as that ECCO2R therapy in addition to conventional treatments and conventional treatments alone (controls). Groups were compared for 28-day survival, iMV duration, and length of stay (LOS).ResultsECCO2R therapy was noted in 75 of the cases among included 395 patients (COPD n = 256, ARDS n = 139) out of scanned 1715 medical records. The survival rate of ECCO2R patients was 68% and significantly higher than 58% survival rate of controls (p = 0.025), with relative risk reduction (RRR) = 0.16, absolute risk reduction (ARR)= 0.10, number need to treat (NNT) = 10, and odds ratio (OR) = 1.5. In addition, iMV duration (12.8 ± 2.6 vs. 17.1 ± 4.9 days, p = 0.007) and LOS (16.9 ± 4.1 vs. 18.9 ± 5.5 days, p = 0.032) were significantly shorter than controls. Repeated measure analyses showed that LPV settings were successfully provided by 72 h of ECCO2R therapy. Subgroup analyses according to diagnoses of COPD and ARDS also favored ECCO2R.ConclusionECCO2R therapy significantly improved survival, iMV duration and LOS in patients with severe HRF due to COPD or ARDS, and successfully provided LPV approaches. Further studies are needed to assess promising benefits of ECCO2R therapy.

Project description:ObjectivesLower tidal volume ventilation (targeting 3 mL/kg predicted body weight, PBW) facilitated by extracorporeal carbon dioxide removal (ECCO2R) has been investigated as a potential therapy for acute hypoxemic respiratory failure (AHRF) in the pRotective vEntilation with veno-venouS lung assisT in respiratory failure (REST) trial. We investigated the effect of this strategy on cardiac function, and in particular the right ventricle.DesignSubstudy of the REST trial.SettingNine U.K. ICUs.PatientsPatients with AHRF (Pao2/Fio2 < 150 mm Hg [20 kPa]).InterventionTransthoracic echocardiography and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements were collected at baseline and postrandomization in patients randomized to ECCO2R or usual care.MeasurementsThe primary outcome measures were a difference in tricuspid annular plane systolic excursion (TAPSE) on postrandomization echocardiogram and difference in NT-proBNP postrandomization.ResultsThere were 21 patients included in the echocardiography cohort (ECCO2R, n = 13; usual care, n = 8). Patient characteristics were similar in both groups at baseline. Median (interquartile range) tidal volumes were lower in the ECCO2R group compared with the usual care group postrandomization; 3.6 (3.1-4.2) mL/kg PBW versus 5.2 (4.9-5.7) mL/kg PBW, respectively (p = 0.01). There was no difference in the primary outcome measure of mean (sd) TAPSE in the ECCO2R and usual care groups postrandomization; 21.3 (5.4) mm versus 20.1 (3.2) mm, respectively (p = 0.60). There were 75 patients included in the NT-proBNP cohort (ECCO2R, n = 36; usual care, n = 39). Patient characteristics were similar in both groups at baseline. Median (interquartile range [IQR]) tidal volumes were lower in the ECCO2R group than the usual care group postrandomization; 3.8 (3.3-4.2) mL/kg PBW versus 6.7 (5.8-8.1) mL/kg PBW, respectively (p < 0.0001). There was no difference in median (IQR) NT-proBNP postrandomization; 1121 (241-5370) pg/mL versus 1393 (723-4332) pg/mL in the ECCO2R and usual care groups, respectively (p = 0.30).ConclusionsIn patients with AHRF, a reduction in tidal volume facilitated by ECCO2R, did not modify cardiac function.

Project description:BackgroundPatients presenting with acute hypercapnic respiratory failure due to exacerbations of chronic obstructive pulmonary disease (AECOPD) are typically managed with non-invasive ventilation (NIV). The impact of low-flow extracorporeal carbon dioxide removal (ECCO2R) on outcome in these patients has not been explored in randomised trials.MethodsOpen-label randomised trial comparing NIV (NIV arm) with ECCO2R (ECCO2R arm) in patients with AECOPD at high risk of NIV failure (pH < 7.30 after ≥ 1 h of NIV). The primary endpoint was time to cessation of NIV. Secondary outcomes included device tolerance and complications, changes in arterial blood gases, hospital survival.ResultsEighteen patients (median age 67.5, IQR (61.5-71) years; median GOLD stage 3 were enrolled (nine in each arm). Time to NIV discontinuation was shorter with ECCO2R (7:00 (6:18-8:30) vs 24:30 (18:15-49:45) h, p = 0.004). Arterial pH was higher with ECCO2R at 4 h post-randomisation (7.35 (7.31-7.37) vs 7.25 (7.21-7.26), p < 0.001). Partial pressure of arterial CO2 (PaCO2) was significantly lower with ECCO2R at 4 h (6.8 (6.2-7.15) vs 8.3 (7.74-9.3) kPa; p = 0.024). Dyspnoea and comfort both rapidly improved with commencement of ECCO2R. There were no severe or life-threatening complications in the study population. There were no episodes of major bleeding or red blood cell transfusion in either group. ICU and hospital length of stay were longer with ECCO2R, and there was no difference in 90-day mortality or functional outcomes at follow-up.InterpretationThere is evidence of benefit associated with ECCO2R with time to improvement in respiratory acidosis, in respiratory physiology and an immediate improvement in patient comfort and dyspnoea with commencement of ECCO2R. In addition, there was minimal clinically significant adverse events associated with ECCO2R use in patients with AECOPD at risk of failing or not tolerating NIV. However, the ICU and hospital lengths of stay were longer in the ECCO2R for similar outcomes. Trial registration The trial is prospectively registered on ClinicalTrials.gov: NCT02086084. Registered on 13th March 2014, https://clinicaltrials.gov/ct2/show/NCT02086084?cond=ecco2r&draw=2&rank=8.

Project description:Mechanical ventilation with a tidal volume (VT) of 6 mL/kg/predicted body weight (PBW), to maintain plateau pressure (Pplat) lower than 30 cmH2O, does not completely avoid the risk of ventilator induced lung injury (VILI). The aim of this study was to evaluate safety and feasibility of a ventilation strategy consisting of very low VT combined with extracorporeal carbon dioxide removal (ECCO2R).In fifteen patients with moderate ARDS, VT was reduced from baseline to 4 mL/kg PBW while PEEP was increased to target a plateau pressure--(Pplat) between 23 and 25 cmH2O. Low-flow ECCO2R was initiated when respiratory acidosis developed (pH < 7.25, PaCO2 > 60 mmHg). Ventilation parameters (VT, respiratory rate, PEEP), respiratory compliance (CRS), driving pressure (DeltaP = VT/CRS), arterial blood gases, and ECCO2R system operational characteristics were collected during the period of ultra-protective ventilation. Patients were weaned from ECCO2R when PaO2/FiO2 was higher than 200 and could tolerate conventional ventilation settings. Complications, mortality at day 28, need for prone positioning and extracorporeal membrane oxygenation, and data on weaning from both MV and ECCO2R were also collected.During the 2 h run in phase, VT reduction from baseline (6.2 mL/kg PBW) to approximately 4 mL/kg PBW caused respiratory acidosis (pH < 7.25) in all fifteen patients. At steady state, ECCO2R with an average blood flow of 435 mL/min and sweep gas flow of 10 L/min was effective at correcting pH and PaCO2 to within 10 % of baseline values. PEEP values tended to increase at VT of 4 mL/kg from 12.2 to 14.5 cmH2O, but this change was not statistically significant. Driving pressure was significantly reduced during the first two days compared to baseline (from 13.9 to 11.6 cmH2O; p < 0.05) and there were no significant differences in the values of respiratory system compliance. Rescue therapies for life threatening hypoxemia such as prone position and ECMO were necessary in four and two patients, respectively. Only two study-related adverse events were observed (intravascular hemolysis and femoral catheter kinking).The low-flow ECCO2R system safely facilitates a low volume, low pressure ultra-protective mechanical ventilation strategy in patients with moderate ARDS.

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Alkaline Liquid Ventilation of the Membrane Lung for Extracorporeal Carbon Dioxide Removal (ECCO₂R): In Vitro Study.

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Alkaline Liquid Ventilation of the Membrane Lung for Extracorporeal Carbon Dioxide Removal (ECCO2R): In Vitro Study.

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OmicsDI is part of the ELIXIR infrastructure

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Alkaline Liquid Ventilation of the Membrane Lung for Extracorporeal Carbon Dioxide Removal (ECCO₂R): In Vitro Study.