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Acid Base Disorders

Acid-base disorders are pathological changes in arterial pH and carbon dioxide partial pressure (Pco2), and in serum bicarbonate (HCO3-).

Normal acid base values:

                                                               pH                  PCO2                HCO3-

                                 Range:              7.35- 7.45            36-44                22-26

                                 Optimal value      7.40                     40                     24

Classification: 

Metabolic acidosis is serum HCO3- <24 mEq / L. Causes are

Increased acid production

Acid ingestion

Decreased renal acid excretion

GI or renal HCO3-loss

Metabolic alkalosis is serum HCO3-> 24 mEq / L. Causes are

Acid loss

HCO3- retention

Respiratory acidosis is Pco2> 40 mm Hg (hypercapnia). Cause is

Decrease in minute ventilation (hypoventilation)

Respiratory alkalosis is Pco2 <40 mm Hg (hypocapnia). Cause is

Increase in minute ventilation (hyperventilation)

References

- http://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/acid-base-regulation-and-disorders/acid-base-disorders

- http://fitsweb.uchc.edu/student/selectives/TimurGraham/Introduction_to_Acid_Base_disorders.html