Metabolic Effects of Sodium Bicarbonate in Management of Diabetic Ketoacidosis

Abstract

Biochemical analyses of blood and cerebrospinal fluid of nine patients with diabetic ketoacidosis and impaired levels of consciousness were performed before and after four hours of intravenous therapy with insulin, saline, and bicarbonate. A comparison with previously reported data from a similar group of patients treated with insulin and saline alone revealed no significant differences in blood or cerebrospinal fluid with the following exceptions. First, the fall in CSF osmolality was significantly less after insulinsaline-bicarbonate therapy than in patients receiving only insulin and saline. Second, CSF pH values declined in both groups with therapy but were significantly lower in the group receiving insulin-saline-bicarbonate. Definite and progressive clinical improvement was noted in all nine patients from admission to discharge. It was concluded that the use of sodium bicarbonate did not discernibly alter the clinical course of the nine patients studied except for the unexplained slower decline in CSF osmolality. The use of NaHCO3 appears to be indicated primarily in situations in which prompt correction of metabolic acidosis is essential, e.g., to improve cardiovascular function.

Diabetic Ketoacidosis in Infants, Children, and Adolescents

“…The maximum recommended rate of intravenous potassium replacement is usually 0.5 mmol ⅐ kg Ϫ1 ⅐ h Ϫ1 . (83,84) and hypokalemia from rapid correction of acidosis (83,85,86). Failure to account for the sodium being administered and appropriately reducing the NaCl concentration of the fluids can result in increasing osmolality (83).…”

Acid-Base Aspects of Ketoacidosis

“…Nevertheless, the concept that alkali should not be given overenthusiastically or without proper indi cation appears to have gained much support [91,99]. Too rapid correction of the acidemia may result in or may aggravate a paradoxical decrease in spinal fluid pH if the cerebral spinal fluid PCO2 increases more rapidly than does cerebrospinal fluid [HCO3], since bicarbonate is less diffusible than carbon dioxide across the blood-brain barrier [91,100]. Also, sudden correction of blood pH may impair oxygen delivery by removing the protective effect of acidosis on the hemoglobin-oxygen dissociation curve at a time when red blood cell 2,3-diphosphoglycerate is low [101].…”

Central nervous system pH in uremia and the effects of hemodialysis.

“…Because of the blood-brain barrier, when plasma bicarbonate is elevated with intravenously administered NaHCO3, plasma and CSF bicarbonate levels will not equilibrate for several hours, while Pcoa equilibrates within minutes (21,22). Thus, when hypoventilation results in a rise of arterial Pco2, the pH in CSF will fall as C02 rapidly diffuses into the CSF (21)(22)(23).…”

“…In 18 patients with diabetic ketoacidosis in whom pH of CSF was evaluated during therapy (22)(23)(24), pH of CSF fell from 7.30 to 7.20 while arterial pH rose from 7.08 to 7.34. However, the fall in pH of CSF was entirely due to a rise in CSF PcO2 (from 24 to 34 mm Hg), as bicarbonate in CSF actually rose slightly (from 10.9 to 12.1 mmol/liter).…”