Clinical Research Directory

Safety and Efficacy of Low-Flow ECMO in a Multi-modal Cohort of Adults in Respiratory Failure

Sponsor: Institute for Extracorporeal Life Support

Summary

The current standard of care (SOC) for treatment of patients with acute respiratory distress syndrome (ARDS), inhalation injury, volume overload, and/or pulmonary dysfunction is mechanical ventilation (MV). However, these techniques are associated with several complications after prolonged use, including risk of infection, increased sedation requirements, pulmonary edema, ventilator-induced lung injury (VILI), barotrauma, and multi-organ failure. Extracorporeal life support (ECLS) has been used to successfully minimize, replace, or avoid the use of MV. This concept is critical as it permits ultra-lung protective MV settings, mobilization, early ambulation of patients, and timely extubation (when appropriate). Conventional ECLS typically requires blood flows of 3-6 L/min, and its cannula sizes range from 21-25 Fr. This is by definition "high-flow" as it constitutes near-complete extracorporeal circulation of patient's circulating blood volume. On the other hand, low-flow ECLS at 1-2.5 L/min has been shown to prevent deleterious shifts in pH and PaCO2 at a lower level of invasiveness, and its cannula sizes range from 19-20 Fr dual lumen cannulas (which are associated with less serial dilation). The investigators propose the use of a low-flow circuit to include the NovaLung system in conjunction with a smaller tubing set and cannula to enable earlier utilization of ECLS with less invasiveness and smaller catheters. Specifically, the study will either utilize the Crescent RA cannula (or equivalent dual-lumen cannula) or use a 15-25 Fr cannula, both with 3/8 tubing/step-down tubing, as needed, for our study. A femoral (fem)-femoral or femoral-internal jugular (IJ) approach may also be used. Carbon dioxide is six times more diffusible than oxygen across the membrane; thus, carbon dioxide transfers can occur with high efficiency at our targeted blood flows of 1-2.5L/min. Oxygen can still transfer at these blood flows, and low flow can improve oxygen levels to some degree. There are three benchtop-based manuscripts that suggest that low-flow ECMO is associated with a potential increase in factors that increase the risk of bleeding complications/circuit changes. However, the manuscripts either tested \<1 L/min blood flow rates, or the effect of cannula size was not considered. None of them included the biological component of endothelial interaction. Mitigating the risk of bleeding complications by will be completed by administering anticoagulants with a target PTT of 40-50 seconds, and by monitoring the patients and their coagulation panels closely. There may be less risk of circuit clotting in our study because of chosen flow rates (1-2.5 L/min).

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