Metabolic Acid-Base Disturbances:

• Metabolic acidosis results from a decrease in cations or increase in anions leading to SID < 39 mEq/L.
• Metabolic alkalosis results from SID > 42 mEq/L.

Strong Anion Gap (SIG):

• SIG reflects metabolic acidosis due to the presence of more anions than cations, such as ketones in diabetic ketoacidosis.
• SIG ranges from 0 to 2 mEq/L.

Stewart Method:

• Describes six acid-base disorders based on variations in three independent variables: pCO2, A TOT, and SID.
• Useful in analyzing complex acid-base disorders but requires additional measurements and complex calculations.

Normal Acid-Base Homeostasis:

• Body's metabolic processes generate volatile and fixed acids that must be buffered and excreted to maintain pH within a narrow range of 7.35-7.45.
• Bicarbonate carbonic acid buffer system is essential in regulating extracellular fluid.

Acid-Base Disorders Quantification:

• Can be quantified using the physiologic, base excess, and physiochemical approaches.
• The Stewart method differs significantly from the other two approaches by not attributing a central role to HCO3-.

Stewart Approach:

• Changes in plasma [H+] are related to pCO2, total concentration of weak acids (A TOT), and strong ion difference (SID).
• SID is determined by the difference between the total concentration of strong cations and strong anions.

Acid-Base Homeostasis Maintenance:

• The kidney's role in maintaining acid-base balance involves reabsorption of filtered bicarbonate and excretion of fixed daily acid load.