IN-VITRO CHANGES IN THE TRANSPARENCY AND PH OF CEREBROSPINAL-FLUID CAUSED BY ADDING MIDAZOLAM

The effects of adding midazolam and bupivacaine to human cerebrospinal fluid in glass test tubes were examined by looking for changes in pH and a reduction in the transparency of the solution. Midazolam (n=6), 0.25% bupivacaine (n=6), 5 mg of midazolam in 6 mL of 0.25% bupivacain e (n=6) and 5 mg of midazolam in 10 mt of saline (n=6) were added to 1 .5-mL samples (n=24) of cerebrospinal fluid taken at the time spinal a naesthesia was begun. Transparency and pH were checked after each incr ement. Cerebrospinal pH was decreased to below 7.0 by adding more than 3 mg of midazolam, more than 1.9 mt of 0.25% bupivacaine or 1.3 mt of the mixture. Cerebrospinal transparency was decreased by adding more than 0.7 mg of midazolam, 1.1 mt of 0.25% bupivacaine or 0.6 mL of the mixture. Midazolam in saline neither decreased the pH below 7.0 nor r educed transparency. These results do not suggest that clinically usef ul doses of intrathecal or epidural midazolam are neurotoxic.