Importance of the Effective Strong Ion Difference of an Intravenous Solution in the Treatment of Diarrheic Calves with Naturally Acquired Acidemia and Strong Ion (Metabolic) Acidosis

Background The effect of sodium bicarbonate on acid‐base balance in metabolic acidosis is interpreted differently by H enderson‐ H asselbalch and strong ion acid‐base approaches. Application of the traditional bicarbonate‐centric approach indicates that bicarbonate administration corrects the metabolic acidosis by buffering hydrogen ions, whereas strong ion difference theory indicates that the co‐administration of the strong cation sodium with a volatile buffer (bicarbonate) corrects the strong ion acidosis by increasing the strong ion difference ( SID ) in plasma. Objective To investigate the relative importance of the effective SID of IV solutions in correcting acidemia in calves with diarrhea. Animals Twenty‐two H olstein‐ F riesian calves (4–21 days old) with naturally acquired diarrhea and strong ion (metabolic) acidosis. Methods Calves were randomly assigned to IV treatment with a solution of sodium bicarbonate (1.4%) or sodium gluconate (3.26%). Fluids were administered over 4 hours and the effect on acid‐base balance was determined. Results Calves suffered from acidemia owing to moderate to strong ion acidosis arising from hyponatremia and hyper‐ d ‐lactatemia. Sodium bicarbonate infusion was effective in correcting the strong ion acidosis. In contrast, sodium gluconate infusion did not change blood pH , presumably because the strong anion gluconate was minimally metabolized. Conclusions A solution containing a high effective SID (sodium bicarbonate) is much more effective in alkalinizing diarrheic calves with strong ion acidosis than a solution with a low effective SID (sodium gluconate). Sodium gluconate is ineffective in correcting acidemia, which can be explained using traditional acid‐base theory but requires a new parameter, effective SID , to be understood using the strong ion approach.