Evaluation of Membrane Lung Function for Patients Receiving Venovenous Extracorporeal Membrane Oxygenation in High-altitude Regions

Over the last 20 years, extracorporeal membrane oxygenation (ECMO) has been used to support adult patients with respiratory or cardiac failure who are unlikely to survive conventional treatment methods. ECMO circuit, pump, and oxygenator technology improvements permit safer perfusion for extended periods. The prolonged use of an ECMO circuit increases the risk of membrane lung (ML) dysfunction. The ML is responsible for taking in oxygen and removing carbon dioxide. The non-biologic surface of the ML triggers inflammatory and coagulation pathways, resulting in the formation of blood clots, breakdown of fibrin, and activation of white blood cells, which ultimately leads to ML dysfunction. Coagulation and fibrinolysis activation can cause systemic coagulopathy or hemolysis, and the deposition of blood clots can block blood flow. Moreover, the accumulation of moisture in the gas phase and the buildup of protein and cellular debris in the blood phase may contribute to shunt and dead-space physiology, respectively, impairing the exchange of gases. These three categories-hematologic abnormalities, mechanical obstruction, and inadequate gas exchange-account for most ML exchanges. Worsening oxygenation during ECMO should prompt quantification of oxygen transfer. ML exchange is indicated when the ML can no longer meet the patient's oxygen demand. The partial pressure of Post-ML arterial oxygen less than 200 mmHg is the most important consideration in this decision. In some high-altitude regions of China, ECMO treatment is also routinely conducted. The experiences above are derived from low-altitude areas, and whether they apply in high-altitude regions is still being determined. This study aimed to explore the significantly lower membrane lung oxygen uptake in high-altitude regions compared to low-altitude areas.