From the April 2017 issue of HealthCare Business News magazine
Optimizing surgical conditions represents another viable strategy. For example, cardio-protective anesthetics such as desflurane, isoflurane and sevoflurane have been evaluated in the past as a means to protect the heart during and after surgery by a variety of mechanisms, including helping to reduce cardiac ischemia and reperfusion injury and to control inflammation.
An improved CPB design called minimized extracorporeal circulation (MECC) is another innovation in cardiac surgery. MECC combines shortened blood lines coated with heparin and other techniques designed to minimize blood contact with air and the blood circuit — known triggers for complement activation and cytokine release. MECC has been commercially available for nearly two decades and has been adopted by many centers. Although MECC has not demonstrated improved mortality compared to regular CPB, it has been associated in some studies with a reduction in adverse events such as stroke and the need for vasopressors as well as faster ventilator weaning and shorter ICU stays.
Another current and future strategy is the direct removal of free hemoglobin, cytokines, activated complement and other substances from whole blood during CPB. In the past, this was not technically possible, but led to the intraoperative use of leukoreduction filters that tried to indirectly lower cytokines by reducing circulating leukocytes that produced them.
A more advanced blood purification technology called CytoSorb, approved in the European Union, has been used to directly and safely reduce these inflammatory mediators in more than 4,000 open heart surgeries. CytoSorb is a hemoperfusion cartridge filled with hemocompatible, porous polymer beads the size of a grain of salt that rapidly reduce substances from blood using size exclusion, pore capture and adsorption. It is used during CPB and installs directly into a bypass circuit (post-pump to venous reservoir) at approximately a tenth of the blood flow of the main blood circuit. In small, randomized, controlled trials, CytoSorb has been used safely in mild to high-risk cardiac surgery patients, reducing cytokines, free hemoglobin and activated complement C3a and C5a, while leading to decreased sterna wound infections and reduced ICU times.
A large-scale U.S. randomized, controlled trial called REFRESH (REduction in FREe Hemoglobin) II, intended to support FDA approval of CytoSorb, will start later this year. This study will evaluate intraoperative CytoSorb use during elective, complex cardiac surgery, on clinical outcomes and reductions in adverse events. Complications from uncontrolled inflammation after surgery can be life-altering and even deadly.
