How much amount of cerebro spinal fluid can be drawn from a tolerant for diagnosis?
Answers: The amount of CSF withdrawn for sampling depends on the investigation required. In practice, approximately 5–10 ml of CSF are usually withdrawn, although investigations for cell count and Gram stain can be performed using 1 ml. The pressure of CSF can be measured at the time of lumbar puncture using a manometer. Normal CSF pressure falls within a range of 60–180 mmH2O (Hickey 2002). Spinal pressure may be raise in the presence of cerbrovascular accident, a space-occupying lesion or bacterial meningitis.
I think the max is 30-40 cc depending on what they are conducting tests for.
CSF is formed primarily by filtration and secretion from networks of capillaries, called choroid plexuses, located in the ventricles of the brain. Eventually, digestion takes place through the arachnoid villi, which are finger-like projections of the arachnoid mater that push into the dural venous sinuses. CSF is clear, colourless and slightly alkaline, with a specific gravity of 1007 (Hickey 2002). In an adult, approximately 500 ml of CSF are produced and reabsorbed respectively day (Weldon 1998), with 120–150 ml present at one time. CSF constituents include:
o Water
o Mineral salts
o Glucose
o Protein (16–45 mg/dl) (Hickey 2002)
o Urea and creatinine.
The functions of CSF include:
o To achievement as a shock absorber
o To carry nutrients to the brain
o To remove metabolites from the brain
o To support and protect the brain and spinal cord
o To keep the brain and spinal cord moist .
I have once in a while seen much more than 10cc removed for testing. This includes various test for chemical, microbiological, and serological analysis. I have seen few cases where this amount is not sufficient to run a full mobile of laboratory tests. Between 2- 4 mls is more than sufficient to perform most of the microbiological and biochemical investigations.
CSF should never be "drawn" but, to allow it to "drop" into the sterile specimen bottle. Drops of 5 and 6 in respectively specimen bottle is sufficient.
Hope, this helps
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