Authors NS Ngwenya University of the Witwatersrand Keywords: balanced acid base status, arterial blood gas Abstract

A balanced acid-base status is critical for regular cellular and organ function and the survival of an organism. An arterial blood gas (ABG) machine is an accessible bedside tool of measurement, accessing both respiratory and metabolic disorders. Correct sampling, avoidance of common analytical errors, and correct interpretation of results are critical in guiding the administration of appropriate therapy. The adage “never do the test if you are not sure what to do with the results” is relevant concerning ABG analysis.

Historically and traditionally, the lungs and the kidneys have been considered important organs regulating acid-base balance. Next to these organs, the liver is now recognised as an important contributor to acid-base homeostasis. Understanding the collaboration, metabolic communication, and physiological interactions of these organs is crucial in understanding any acid-base derangement. These organs are the most important effectors, normalising the acid-base status.

An excess of metabolic acid is converted to volatile acid (CO₂) by the respiratory metabolic link and excreted by the lungs. Likewise, an excess of volatile acid is converted to metabolic acid and excreted by the kidney. This system is non-saturable. The hepatorenal link regulates the amount of bicarbonate generated or consumed, based on the alkalinity or acidity of arterial blood.

Author Biography NS Ngwenya, University of the Witwatersrand

Department of Anaesthesia, School of Clinical Medicine, Faculty of Health Sciences, Thelle Mogoerane Regional Hospital, University of the Witwatersrand, South Africa

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