Systemic response to pneumonia in the critically ill patient.

Pneumonia is a very common admission diagnosis of critically ill patients. Patients with severe episodes of pneumonia are at risk for development of the systemic inflammatory response syndrome, which is known to induce the production of proinflammatory cytokines, such as interleukins (ILs) and tumor necrosis factor alpha (TNF-alpha). This response subsequently triggers activation of anti-inflammatory cytokine production and specific soluble cytokine receptors. Lung cell apoptosis can be stimulated or inhibited by different cytokines and/or cell signals. Some of these mediators can be proapoptotic or antiapoptotic. This article discusses the clinical implications of the systemic response to pneumonia in the critically ill patient.