[Design of a dedicated connecting tube for extracorporeal carbon dioxide removal therapy]

Extracorporeal carbon dioxide removal (ECCO₂R) is a type of extracorporeal circulation technology. It generally refers to a technique that mimics the modality of veno-venous extracorporeal membrane oxygenation (VV-ECMO), aiming to eliminate carbon dioxide from the blood and correct hypercapnia with a relatively low blood flow. The removal efficacy of ECCO₂R depends on blood flow, gas flow rate, membrane lung surface area, and the partial pressure gradient of carbon dioxide (PCO₂) across the membrane. Currently, the surface area of gas exchangers used in clinical practice is generally less than 1 m². Therefore, ensuring the achievement of the target blood flow during ECCO₂R therapy is crucial to its effectiveness. However, the catheters currently available in clinical settings fail to deliver a blood flow of 400-500 mL/min, necessitating technical improvements. To address this clinical challenge, the medical staff of critical care medicine department of Zhongda Hospital, Southeast University designed a dedicated connecting tube for ECCO₂R therapy, which has been granted a National Utility Model Patent of China (ZL 2023 2 2120568.4). The main structure of this dedicated tube comprises three central venous catheters arranged in a Y shape: central venous catheter 1, central venous catheter 2, and central venous catheter 3. Catheters 1 and 2 are connected in parallel, and in series with catheter 3. The front-end connectors of catheters 1 and 2 are fitted with sterile protective caps, while the rear end of catheters 3 is equipped with a membrane lung connector for connection to the membrane lung. Separate side tubes are attached to the outer sides of catheter 1 and catheter 2 respectively, for connecting irrigation fluid, releasing pressure in the blood drainage segment, and shortening the pause time of extracorporeal circulation during ECCO₂R. Clamps are installed on the catheter 1, catheter 2, catheter 3, and the side tubes. The dedicated connecting tube for ECCO₂R features a simple in structure, easy to operate, and highly practical. The improved connecting tube can achieve a blood flow of 400-500 mL/min, which ensures the therapeutic effect of ECCO₂R and renders it suitable for clinical promotion.