Cardenas Victor J, Miller Lucinda, Lynch James E, Anderson Michael J, Zwischenberger Joseph B
Departments of Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
ASAIO J. 2006 Jul-Aug;52(4):467-70. doi: 10.1097/01.mat.0000227743.07743.5d.
Extracorporeal CO2 removal may reduce minute ventilation requirements and allow for better tolerance of low tidal volume ventilating strategies in patients with severe respiratory insufficiency. Conventional extracorporeal gas exchange is labor-intensive, expensive, and usually requires systemic anticoagulation. In this study, a simplified venovenous circuit was developed by using regional citrate anticoagulation to avoid potential complications associated with systemic heparin. Five healthy adult sheep underwent percutaneous placement of a double-lumen 18F catheter into the internal jugular vein. The extracorporeal circuit consisted of a hollow fiber oxygenator and a variable speed roller pump. Regional anticoagulation consisted of a continuous citrate infusion to the inflow limb of the circuit. Systemic calcium levels were maintained by calcium chloride infusion through a central line. CO2 transfer was measured at varying levels of blood and gas flow. CO2 transfer ranged from 31 ml/min (500 ml/min blood flow; 2 l/min gas flow) to 150 ml/min (1000 ml/min blood flow; 15 l/min gas flow) and was directly proportional to blood flow and gas flow (p < 0.05). Normocapnia was maintained despite a 75% reduction in minute ventilation. At 24 hours, there was no significant clot formation in the circuit.
体外二氧化碳清除可能会降低分钟通气需求，并使严重呼吸功能不全患者对低潮气量通气策略有更好的耐受性。传统的体外气体交换劳动强度大、成本高，且通常需要全身抗凝。在本研究中，通过使用局部柠檬酸盐抗凝来避免与全身肝素相关的潜在并发症，开发了一种简化的静脉 - 静脉回路。五只健康成年绵羊经皮将双腔18F导管置入颈内静脉。体外回路由中空纤维氧合器和变速滚压泵组成。局部抗凝包括向回路的流入肢体持续输注柠檬酸盐。通过中心静脉导管输注氯化钙来维持全身钙水平。在不同的血流和气体流量水平下测量二氧化碳转运。二氧化碳转运范围为31毫升/分钟（血流500毫升/分钟；气体流量2升/分钟）至150毫升/分钟（血流1000毫升/分钟；气体流量15升/分钟），并且与血流和气体流量成正比（p < 0.05）。尽管分钟通气量减少了75%，但仍维持了正常碳酸血症。24小时时，回路中无明显血栓形成。
