EFFECTS OF THAM AND SODIUM-BICARBONATE ON INTRACRANIAL-PRESSURE AND MEAN ARTERIAL-PRESSURE IN AN ANIMAL-MODEL OF FOCAL CEREBRAL INJURY

Episodes of arterial hypotension are associated with an increased mort ality in head injury patients. Rapid infusion of sodium bicarbonate in such patients may cause hypotension and elevate intracranial pressure . Therefore, we examined the effects of tromethamine (THAM) versus bic arbonate on intracranial pressure and blood pressure in a model of foc al cerebral injury. THAM is a buffer that in previous studies has been shown to lower intracranial pressure. After creation of a cryogenic l esion in 13 New Zealand white rabbits, equivalent infusions (15 s dura tion) of sodium bicarbonate and THAM (2 mEq/kg) were administered sequ entially to each animal in random order. Rapid infusion was chosen to simulate the administration of these drugs during a resuscitation. THA M infusion was associated with a significantly lower intracranial pres sure and blood pressure than bicarbonate. The fall in blood pressure w as great enough that cerebral perfusion pressure after THAM infusion w as significantly lower than after bicarbonate infusion. In this model of cerebral injury, rapid infusion of THAM offered no therapeutic adva ntage over bicarbonate.