Concentrations of atracurium and laudanosine in cerebrospinal fluid and plasma in three intensive care patients.

We have measured concentrations of atracurium and laudanosine in cerebrospinal fluid (CSF) and plasma in three intensive care patients receiving atracurium infusions of 22.5-106 h duration to maintain neuromuscular block. Two patients had suffered severe closed head injuries and the third patient had developed respiratory failure following the clipping of two intracranial aneurysms. The total dose of atracurium given was 14.3-136.6 mg kg-1; rate of infusion was 0.6-1.38 mg kg-1 h-1. Plasma concentrations of atracurium and laudanosine were 0.73-3.11 micrograms ml-1 and 0.48-8.65 micrograms ml-1, respectively; CSF concentration of laudanosine was 70-440 ng ml-1. No adverse effects attributable to these concentrations of laudanosine were observed.