Protein metabolism in critical illness

In summary, protein metabolism of critically ill patients is a field open to new investigations that will help us to understand better the mechanism behind ‘autocannibalism’, which is still today associated with mortality. Although the underlying disease is the major determinant of mortality, nutritional depletion will add morbidity, an addition that grows over time in the ICU. With conventional treatment the velocity of the catabolic process can at best be slowed down and the patient be bought time for other types of treatment to work. New forms of specific nutrition and adjuvant therapies may give us tools to prevent muscle depletion, without endangering the supply of essential substrates to the tissues in the splanchnic area. Muscle is at present a limiting organ for the ICU patient in two respects. A depleted muscle can no longer provide enough substrates for the splanchnic organs to maintain intestinal integrity and to maintain a high immunocompetence. In addition, a depleted muscle will be restored back to normal only very slowly; in elderly patients restoration may not even occur at all. The effects of an attenuation of muscle depletion on rehabilitation time have yet to be evaluated. An understanding of protein metabolism may be the key to better patient care in the ICU in the future.