EFFECT OF BOLUS DOSES OF MIDAZOLAM ON INTRACRANIAL-PRESSURE AND CEREBRAL PERFUSION-PRESSURE IN PATIENTS WITH SEVERE HEAD-INJURY

We have studied the effects of bolus doses of midazolam 0. 15 mg kg-1 i. v. on intracranial pressure (ICP), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) in 12 patients with severe head injury (Glasgow Coma Scale score less-than-or-equal-to 6). The study was performed in patients aged 17-44 yr who were sedated (phenoperidine 20 mug kg-1 h-1) and paralysed (vecuronium 2 mg h-1). Midazolam reduced MAP from 89.0 mm Hg to 75.0 mm Hg (P < 0.0001), while CPP decreased from 71.0 mm Hg to 55.8 mm Hg (P < 0.0001). During the study, CPP decreased to less than 50 mm Hg in four patients. Midazolam induced small, non-significant changes in ICP. However, when control ICP was less than 18 mm Hg (n = 7 patients), an increase in ICP was observed. The remaining five patients (control ICP greater-than-or-equal-to 18 mm Hg) exhibited a slight decrease in ICP. These findings suggest that bolus administration of midazolam should be performed with great caution in patients with severe head injury, especially when ICP is less than 18 mm Hg.