Two-hit hypothesis and multiple organ dysfunction syndrome.

A severe insult in the form of infection or trauma primes the host immune system so that a subsequent, relatively trivial insult produces a markedly exaggerated host immune response, which can lead to multiple organ dysfunction syndrome (MODS) and death. This forms the basis of the "two-hit hypothesis" (THH), which is being increasingly recognised as an important cause of morbidity and mortality following severe injury and sepsis, particularly in intensive care settings. Appreciation of the impact of repeated insults and pathophysiology of MODS is vital in the prevention of this serious complication. We describe a case which illustrates the concept of THH and MODS and present a review of literature on this subject.