[Density of cerebrospinal fluid and local anesthetics (author's transl)].

The densities of cerebrospinal fluid and of local anesthetics, applicable to isobaric spinal anesthesia, were determined by using the Digital Density Meter DMA 02. The density of CSF showed little variation and at 37 degrees C was 1.00021 +/- 0.00024 g/cm3 (mean +/- SD, n = 22). The density of the local anesthetics bupivacaine 0.5%, carticaine 2%, lidocaine 2%, mepivacaine 2% and prilocaine 2% varied at 25 degrees C between 1.001 and 1.005 g/cm3, at 37 degrees C between 0.997 and 1.001 g/cm3. Tetracaine 0.5% in CBF increased its density by 0.00046 g/cm3. The addition of the vasoconstrictors adrenaline and ornipressine (POR 8) increased the density of the local anesthetic solutions insignificantly. On the basis of the narrow range of variation of CSF density, reliable statements may be made on the density dependent spread of local anesthetics in spinal anesthesia.