Introduction: The noninvasive management of the conservative therapy for intracranial pressure (ICP) with hyperosmolar substances is a central problem in the treatment of brain edema. Using transcranial Doppler (TCD), a continuous monitoring of ICP is now possible, because the TCD pulsatility index (PI) intraindividually closely correlates with the level of ICP.
Patients and methods: We administered an ICP-lowering treatment 113 times in 10 patients with intracranial bleeding or ischemic stroke who also had signs of elevated ICP in the computer tomogram. The treatment was carried out over a period of 9 days, using 50 g each of intravenous sorbitol (n = 38) and mannitol (n = 32) or oral glycerol (n = 43).
Results: PI was significantly lowered between 20.0 and 23.9% (p < 0.01) by all substances in the affected and unaffected sides. The differences between the three substances and the differences between the affected and unaffected sides were not significant. The duration of the therapeutic effect of glycerol (190 +/- 41 min) was significantly longer (p < 0.01) than that of sorbitol (150 +/- 28 min) or mannitol (130 +/- 20 min). The duration of the therapeutic effect was also significantly shorter (p < 0.01) in patients with a high PI (> 1.5). All three substances led to a significant increase (p < 0.01) in minimal (= diastolic) flow velocity (Vmin). The increase was highest for glycerol (56.3 +/-72.6%).
Summary: The decrease in PI under therapy was caused by an increase in Vmin. This indicates that ICP therapy with hyperosmolar substances improves brain edema and does not suggest a therapy-induced vasoconstriction.