The interpretation of acidosis in emergency medicine

Abstract

Acidosis is the consequence of an excess of substances in the body the accumulation of which causes a plasma acid overload despite the highly effective capabilities of blood pH control. There are two types of acidosis: respiratory acidosis which is caused by an excess of CO2 in the blood responsible for a carbonic acid overload and metabolic acidosis resulting in a decrease in plasma bicarbonate. Metabolic acidosis may be secondary to an overload of mineral acid and is usually the consequence of an inability of the kidney to eliminate the physiological acid production. Metabolic acidosis may be also the consequence of an excess of production or a defect in metabolism of the normally produced organic acids. An organic metabolic acidosis is usually due to a cellular energy failure and requires the supply of co-substrates to correct it. The distinction between mineral and organic metabolic acidosis is essential because these metabolic disorders require a different therapeutic approach. This article aims to describe the various tools that the emergency physician can use in everyday practice to understand and analyze the type of acidosis, and suggests a diagnostic step-by-step approach, illustrated by commented case reports. An online consultable teachware is proposed in order to help the clinician to solve complex acid-base disorders. Finally, a brief chapter outlines the modern approach to acid-base imbalances according to the Stewart’s model.