Effect of THAM upon outcome in severe head injury: a randomized prospective clinical trial

Although mortality and morbidity rates from head injury have been reduced substantially by improved prehospital interventions, intensive care, and aggressive management of intracranial pressure (ICP), successful treatment of the primary brain injury has been elusive. In experimental models, tromethamine (THAM) has been effective in treating head injury; this drug acts by entering the cerebrospinal fluid compartment, reducing cerebral acidosis and ICP, and reversing the adverse effects of prophylactic hyperventilation on early recovery. In this randomized prospective clinical trial, THAM was studied to determine if it had beneficial effects in the early management of severe head injuries and if the adverse effects of hyperventilation could be prevented. A total of 149 patients with severe head injury (Glasgow Coma Scale scores of < or = 8) were randomly assigned to either a control or a THAM group. Both groups of patients matched in terms of clinical parameters, including age, sex, number of surgical mass lesions, number in each Glasgow Coma Scale stratum, and first ICP measurement. All patients were treated by a standard management protocol, intubated, mechanically ventilated, and maintained in the pCO2 range of 32 to 35 mm Hg for 5 days. Tromethamine was administered as a 0.3-M solution in an initial loading dose (body weight x blood acidity deficit, average 4.27 cc/kg/hr) given over 2 hours, followed by a constant infusion of 1 ml/kg/hr for 5 days. Outcome was measured at 3, 6, and 12 months postinjury. Although analysis indicated no significant difference in outcome between these two groups at 3 months, 6 months, and 1 year, there was a difference regarding ICP. The time that ICP was above 20 mm Hg in the first 48 hours postinjury was less in patients treated with THAM (p < 0.05). Also, the number of patients requiring barbiturate coma was significantly less in the THAM group (5.48% vs. 18.4%, p < 0.05). The authors conclude that THAM ameliorates the deleterious effect of prolonged hyperventilation, may be beneficial in ICP control, and warrants further study as to the dosage and timing of administration.