Combination of a cannula for lumbar puncture and a capillary element with a hydrodynamic resistor, comprises a specified total volume

摘要

The combination of a cannula for lumbar puncture and a capillary element with a hydrodynamic resistor has a total volume less than one milliliter. The time taken for the liquid flowing through the capillary element to fill a liquid space is used as a basis for calculating the opening pressure of the puncture process.