Multiple organ dysfunction syndrome: Exploring the paradigm of complex nonlinear systems

Objectives: The objectives of this article are to introduce and explore a n ovel paradigm based on complex nonlinear systems, and to evaluate its appli cation to critical care research regarding the systemic host response and m ultiple organ dysfunction syndrome (MODS). Data Sources: Published original work, review articles, scientific abstract s and books, as well as our personal files. Study Selection: Studies were selected for their relevance to the applicati ons of nonlinear complex systems, to critical care medicine, and to the con cepts presented. Data Extraction: We extracted all applicable data. Data Synthesis: Following a brief review of MODS, an introduction to comple x nonlinear systems is presented, including clear concepts, definitions, an d properties. By examining the multiple, nonlinear, interrelated, and varia ble interactions between the metabolic, neural, endocrine, immune, and infl ammatory systems; data regarding interconnected antibody networks; and the redundant, nonlinear, interdependent nature of the inflammatory response, w e present the hypothesis that the systemic host response to trauma, shock, or sepsis must be evaluated as a complex nonlinear system. This model provi des a new explanation for the failure of trials using various antimediator therapies in the treatment of patients with sepsis and MODS. Understanding the host response as a complex nonlinear system offers innovative means of studying critical care patients, specifically by suggesting a greater focus on systemic properties. We hypothesize that analysis of variability and co nnectivity of individual variables offer a novel means of evaluating and di fferentiating the systemic properties of a complex nonlinear system. curren t applications of evaluating variability and connectivity are discussed, an d insights regarding future research are offered. Conclusion: The paradigm offered by the study of complex nonlinear systems suggests new insights to pursue research to evaluate, monitor, and treat pa tients with MOBS.