Metabolic Alkalosis

Abstract

Metabolic alkalosis is a common acid-base disturbance in critically ill patients. In this review we discuss the approach to diagnosis and management of this disorder; particular emphasis is given to the causes most com monly responsible for alkalosis in critical care medicine. We present rules for (1) identifying the presence of metabolic alkalosis, ( 2 ) determining whether the disor der is simple or complicated by a second acid-base dis turbance, and (3) determining the cause: The causes are subdivided into three major groups: Chloride-respon sive, chloride-resistant, and alkali administration. The pathogenesis of each type of alkalosis is discussed sep arately, although we stress that more than one cause may be responsible in critically ill patients. The patho logical consequences of metabolic alkalosis and ap proaches to treatment are reviewed. The major issues relating to the critically ill patient are (1) identification and removal of exogenous sources of alkali, (2) iden tification and minimization of HCl losses or selective NaCl losses, and (3) maneuvers to reduce serum HCO 3 concentration without producing extracellular fluid volume overload.