In vivo carbon dioxide clearance of a low-flow extracorporeal carbon dioxide removal circuit in patients with acute exacerbations of chronic obstructive pulmonary disease

Abstract

Background: Veno-venous extracorporeal carbon dioxide removal allows clearance of CO2 from the blood and is becoming popular to enhance protective mechanical ventilation and assist in the management of acute exacerbations of chronic obstructive pulmonary disease, including the prevention of intubation. The main factor determining CO2 transfer across a membrane lung for any given blood flow rate and venous CO2 content is the sweep gas flow rate. The in vivo characteristics of CO2 clearance using ultra-low blood flow devices in patients with acute exacerbations of chronic obstructive pulmonary disease has not been previously described. Methods: Patients commenced on extracorporeal carbon dioxide removal for acute exacerbations of chronic obstructive pulmonary disease recruited to a randomized controlled trial of non-invasive ventilation versus extracorporeal carbon dioxide removal had pre- and post-membrane circuit gases measured after each increment of sweep gas flow to allow calculation of the transmembrane CO2 clearance. This was compared with the clearance reported by the device and also corrected to inlet PCO2 to allow characterization of the CO2 clearance of the device at different sweep gas flow rates. Results: CO2 clearance was calculated using both the transmembrane CO2 whole-blood content difference and CO2 clearance reported by the device. The two methods demonstrated a linear relationship and agreement with a bias of 14 mL/minute (SD = ±10) and an R2 of 0.92. The membrane CO2 clearance was non-linear with nearly two thirds of total clearance achieved with sweep gas flow below 2 L/minute (VCO2 of 40 ± 16.7 mL/minute) and a plateau above 5 L/minute sweep gas flow (VCO2 64 ± 1 2.4 mL/minute). Conclusion: The extracorporeal carbon dioxide removal device used in the study provides efficient clearance of CO2 at low sweep flow rates which then plateaus. This has implications for how the device may be used in clinical practice, particularly during the weaning phase where the final discontinuation of the device may take longer than anticipated. (ClinicalTrials.gov: NCT02086084, registered 13 March 2014, https://clinicaltrials.gov/ct2/show/NCT02086084 )

Evaluation of a New Extracorporeal CO2 Removal Device in an Experimental Setting

“…In our porcine model, using a fixed blood flow rate of 600 mL/min and a high surface membrane lung (1.8 m 2 ), we reported a CO 2 elimination of 170.00 (160.00-200.00) mL/min using 10 L/min of sweep gas starting with a P pre CO 2 around 102.50 (95.30-118.20). Furthermore, CO 2 elimination progressively increased when increasing the gas flow from 0 to 2 L/min and reached a plateau at sweep gas flows higher than 3-4 L/min, in line with other previous studies [11,16].…”

“…In our animal model, the hemoperfusion membrane was not incorporated and the device was used specifically for CO 2 removal (Figure 1). The CO 2 RESET circuit is customized to receive only 1 4 connectors and connects to either with dual lumen cannulas (13,16,19 French) or two single cannulas.…”

“…Membranes 2021, 10, x FOR PEER REVIEW 3 of 11 customized to receive only ¼ connectors and connects to either with dual lumen cannulas (13,16,19 French) or two single cannulas.…”

“…Respiratory acidosis was induced with a 50% reduction of both the baseline tidal volume (from 8 to 4 mL/kg) and the respiratory frequency, to achieve an end tidal CO 2 (etCO 2 ) between 50 and 60 mmHg (Figure 2). To ensure a pre-membrane lung CO 2 (P pre CO 2 ) between 80-120 mmHg, an external supplementation of 1 L/min CO 2 was provided to the inspiratory side of the ventilator circuit [15,16]. FiO 2 was adjusted to maintain a SpO 2 > 96%.…”

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

“…Carbon dioxide transfer across the membrane lung, CO 2 (in mL × min −1 ), was calculated from the transmembrane lung TCO 2 difference [ 35 ]: where TCO 2PRE represents CO 2 content before the membrane lung while TCO 2POST is the CO 2 content after the membrane lung, blood flow is measured in L × min −1 , and the conversion factor is in mL × mmol −1 .…”