Possible mechanisms of action of hypertonic urea in reducing intracranial pressure

Abstract

Hypertonic urea administered intravenously produced a rapid and marked fall in cerebrospinal fluid pressure in all patients. The degree of pressure reduction was proportional to the dose only if the level of the initial pressure was also considered. After the initial reduction in pressure, half the patients showed a secondary elevation above control levels. Correlation was lacking between the time required for recovery of cerebrospinal fluid pressure and the urea concentrations and osmolalities of blood and cerebrospinal fluid. Several hypotheses are considered as a possible explanation for these discrepancies. No untoward reactions from the hypertonic urea occurred except transient hemo-globinuria in one patient.