Mannitol-induced Metabolic Alkalosis

Abstract

Mannitol is an osmotic diuretic agent useful in a variety of clinical conditions. This study is based on acid-base and electrolyte changes seen after the intravenous infusion of hypertonic mannitol for the prevention of cerebral edema. The study subjects were divided into 3 groups: for group A, an amount of 300-900 mL 15% mannitol was intravenously infused over the period of 60 to 90 minutes; for group B, 1,200-2,600 mL over 12 to 24 hours; and for group C, 3,200-4,900 mL over more than 24 hours. In group A, blood pH is increased from 7.43±0.07 to 7.46±0.04, and plasma HCO3- from 25.3±2.1 to 28.9±2.9 mEq/L, but plasma K+ is decreased from 4.3±0.6 to 3.7±0.8 mEq/L. In group B, blood pH is increased from 7.42±0.02 to 7.47±0.06, and plasma HCO3- from 25.2±1.8 to 29.1±2.9 mEq/L, but plasma K+ is decreased from 4.2±0.3 to 3.8±0.5 mEq/L. In group C, blood pH is increased from 7.41±0.01 to 7.52±0.04, and plasma HCO3- from 24.9±1.2 to 27.7±2.5 mEq/L, but plasma K+ is decreased from 4.2±0.1 to 3.9±0.2 mEq/L. These results showed that intravenous infusion of mannitol could induce metabolic alkalosis and hypokalemia, regardless of its dose. The mannitol induced metabolic alkalosis may be due to increased renal HCO3- production.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on electrolyte and acid‐base variables in dogs with suspected intracranial hypertension

“…Based on previous studies, it is unlikely for substantial diuresis and hypovolemia to be present 1 hour after MAN administration, but they could have developed and contributed to the increase in bicarbonate concentration by T 120 . Alternatively, osmotic diuretics previously have been shown to induce increased renal bicarbonate production 49 . Given the relatively rapid increase in bicarbonate concentration in this group of dogs, however, this seems to be a less likely explanation than a decrease in effective circulating volume.…”

“…Alternatively, osmotic diuretics previously have been shown to induce increased renal bicarbonate production. 49 Given the relatively rapid increase in bicarbonate concentration in this group of dogs, however, this seems to be a less likely explanation than a decrease in effective circulating volume. Mean actual bicarbonate concentrations before MAN administration was in the lower half of the institutional RI in this cohort of dogs.…”