Acid-Base Balance

Body fluids must maintain a normal acid-base balance in order for normal cellular function to sustain health and life. Acid-base balance can be described by measuring the pH (or acidity) of a substance on a scale that ranges from 1 to 14 .1,4 Normally, blood has a pH of 7.35 to 7.45. A pH value outside this range indicates a serious acid-base imbalance. The body has numerous compensatory mechanisms to correct an abnormal pH; however, if these mechanisms fail (Figure 4Go), cellular functions are impaired, and death will eventually result.

Nursebitz.com ALERT: Respiratory acid-base imbalances (acidosis or alkalosis) are triggered by respiratory disorders that result from inspiratory and/or expiratory dysfunction. Metabolic acid-base imbalances (acidosis or alkalosis) are triggered by metabolic disorders such as disorders of the gastrointestinal or renal system.

Acidosis
Acidosis is the result of greater than normal amounts of acid or less than normal amounts of base (alkaline) in the blood (pH <7.35).> excess carbonic acid (due to decreased expiration of carbon dioxide) and can be diagnosed on the basis of the increased PaCO₂ in arterial blood gas sampling. Metabolic acidosis occurs when body fluids contain an excessive amount of metabolic acids or a deficit of bases and can be diagnosed on the basis of the decreased bicarbonate level or base excess in arterial blood samples

Alkalosis
Alkalosis is the result of less than normal amounts of acid or greater than normal amounts of base (alkaline) in the blood (pH >7.45). Respiratory alkalosis occurs when excess carbonic acid is excreted (via increased rate and depth of expiration of carbon dioxide) and can be diagnosed on the basis of the decreased PaCO₂ in arterial blood gas sampling. Metabolic alkalosis occurs when body fluids contain an excessive amount of bases or a deficit of acids and can be diagnosed on the basis of the increased bicarbonate level or base excess in arterial blood gas sampling

Compensatory Mechanisms
The ratio of bicarbonate to carbon dioxide is 20:1, and this ratio is normally maintained through compensatory mechanisms or chemical buffers present in the extracellular fluid, body cells, blood cells, and plasma. Buffer systems maintain acid-base balance in 2 ways: by correcting or altering the component responsible for the imbalance and by compensating through alterations in the component that is not primarily responsible for the imbalance. These buffer systems can act within a fraction of a second to prevent excessive changes in pH