Mechanisms of the inflammatory response

The physiological alterations induced by acute inflammation present significant management challenges for anaesthesiologists. Major surgery, trauma, burns and sepsis all have large inflammatory components. Acute inflammation is characterized by vasodilatation, fluid exudation and neutrophil infiltration. These processes are activated and amplified by a series of intracellular and extracellular factors that tightly co-ordinate the inflammatory process. The innate immune system responds rapidly to infection or injury. Macrophages, natural killer cells, CD8+ T-lymphocytes and neutrophils provide an early response to injurious factors in an effort to contain and eliminate harmful stimuli. The adaptive immune response requires prior exposure to microbial antigens, is mediated primarily by CD4+ T-lymphocytes and serves to further amplify acute inflammation. Although acute inflammation is fundamentally beneficial, severe inflammation can precipitate the systemic inflammatory response syndrome. This syndrome is characterized by hyperinflammation and can cause organ injury, shock and death in its most severe forms. Overall, our understanding of inflammation has increased tremendously during the past 20 years. However, these basic science advances have not yet translated into widespread benefit for patients suffering from trauma, sepsis and systemic inflammation.