We have studied the effects of mannitol and glycerol on raised ICP as monitored by epidural pressure recordings in 65 patients. Four methods of infusion were assessed. In group A, 0.5 g/kg mannitol was infused within 15, 30, or 60 min. In group B, 1.0 g/kg mannitol was infused within 30, 60, or 90 min. In group C, 0.5 g/kg glycerol in 5% fructose was infused within 30, 60, or 90 min. In group D, 1.0 g/kg glycerol was infused within 60, 120, or 180 min.
Results: (a) In group A, there was no difference in the reduction of ICP among the three infusion rates. In group B, the degree of ICP reduction increased with shorter times of infusion. In the groups receiving glycerol, the reduction of ICP was inversely related with the rate of infusion. (b) In every group, it appeared that the slower the infusion rate of the same dosage became, the longer the reduction of ICP lasted. (c) A rebound phenomenon occurred in 12% of the mannitol groups and 34% of the glycerol groups. The dose and the rate of mannitol infusion did not influence the occurrence of the rebound phenomenon. In the glycerol groups, the infusion method did influence the occurrence of rebound phenomenon. Our present study demonstrated that there were differences between mannitol and glycerol infusion in their effectiveness and in the occurrence of rebound phenomenon.