Metabolic acid-base disorders.

Acid-base homeostasis is an important determinant of many physiologic functions. Nowhere is understanding the mechanisms and significance of hydrogen ion (H+) imbalance more important than in critical care management, where patients are threatened with a physiochemical disorder that is often as complex as it is dangerous. Although there may be contentious issues yet unresolved concerning acid-base homeostasis, the incontrovertible fact is that the body at least seems to defend H+ balance as vigorously as it does oxygen transport or perfusion pressure. Equally, there seems to be an important and predictable relation between this balance and other physiochemical variables such as concentrations of other ionic species, carbon dioxide, and plasma proteins. The prudent clinician strives to understand whether or not and how acid-base imbalances are affecting his or her patient and what to do about it.