Acidosis occurs in the main due to increased formation of acid or lack of elimination of formed acid or both. Increased formation of acid is mainly seen in the context of poor tissue perfusion with a switch to anaerobic metabolism and the formation of lactic acid. Decreased elimination of acid is mainly a feature of renal failure. Respiratory acidosis in the context of hypoventilation is caused by the lack of elimination of carbon dioxide with increased formation of HCO .
Accumulation of lactic acid will cause lactic acidosis. The anion gap, see equation 1 is increased. To compensate the body will use its buffer systems to reduce the change in pH , more carbon dioxide will be formed due to the HCO buffer system, see equation 4. The proton concentration in the cerebrospinal fluid will rise and the respiratory centre will be stimulated to increase the frequency and depth of respiration. Consequent to the increased minute ventilation the paCO2 will fall.
|Normal anion gap|
Bile/pancreatic fluid loss
Long or obstructed ileal conduit
Carbonic anhydrase inhibitors
|Renal tubular dysfunction||Renal tubular acidosis
|Acid loading||Ammonium chloride
Parenteral feeding (Arginine and Lysine HCl)
|Increased anion gap|
|Overproduction of acid||Lactic acidosis
Ketoacidosis (diabetic, alcohol, starvation)
|Renal failure||Acute or Chronic|