From Continuous Renal Replacement Therapies to Multiple Organ Support Therapy

The incidence of the multiple organ dysfunction syndrome (MODS) is rapidly increasing in intensive care units (ICU). It usually combines with sepsis and is the most frequent cause of death in the ICU patients. The nature of the ICU patients has changed in the last years. It includes a variety of patients with severe cases due to major surgical interventions, trauma, hemodynamic instability, sepsis, and so on but also older people than previous times. All these situations can easily lead to MODS. In the prior years, the only available and efficient therapy was renal replacement therapy (RRT) for treating acute renal failure, but the development of technology also gives us devices to support the other systems. The adequacy of any artificial organ support is evaluated by how closely it mimics the flexibility and efficacy of the organ systems it seeks to substitute or support. In a sequence of events, such as that created by sepsis and MODS, all these criteria should be applied at the same time but for different organs and different tasks. RRT and especially continuous renal replacement therapies (CRRT) allowed extracorporeal treatment in critically ill patients with hyper catabolism and fluid overload with excellent hemodynamic stability. New techniques in CRRT as high volume hemofiltration have been applied in septic patients with very promising results. In the light of these observations, a new thought arises: Can extracorporeal blood purification have a positive impact on different organ systems? A possible answer might come from the simple observation that all organs share one aspect in common: contact with blood. All extracorporeal therapies also have one aspect in common: treatment of blood. Based on these observations and knowledge of the molecular biology of sepsis, a "humoral" theory of MODS makes pathophysiological sense and its consequence triggers the need to consider extracorporeal therapies as multiple organ support therapies and not just as single organ support.