How to Check Pressure in a Spinal Tap

Cerebrospinal fluid (CSF) is contained within a membrane bag, the meninges, that surrounds the brain and travels down the spinal cord to provide cushioning against injury. CSF also removes waste products from the brain. The presence of diseases, such as meningitis, or injuries, such as a leak in the meninges, can be diagnosed by measuring the CSF pressure during a process called a spinal tap. Increased CSF pressure readings may indicate abnormally high intracranial pressure inside the skull. Decreased readings may indicate tumors on the spinal cord or other conditions.

Things You'll Need

• Sterile stopcock designed for use during a spinal tap
• Sterile manometer designed for use during a spinal tap

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Instructions

• 1

  Establish CSF flow in the lumbar puncture (LP) needle. The individual is lying on his side in a relaxed fetal (lateral decubitus) position with the needle in place. Attach the closed stopcock to the needle as soon as possible to avoid fluid loss that may give an inaccurate low pressure reading.

• 2

  Connect the manometer to the stopcock. The zero mark of the manometer scale should be level with the LP needle.

• 3

  Open the stopcock and allow spinal fluid to flow into the manometer and reach a stable level on the scale. Read the opening pressure and record the information on the individual's chart. Slight fluctuations in the pressure reading should be present from the individual's pulse and breathing.

• 4

  Compare the individual's CSF opening pressure to the normal adult opening pressure of 65-200 mmH2O (5-15 mmHg), 50 mmH2O for newborns, 85 mmH2O for young children and 250 mmH2O for extremely obese adults.

• 5

  Close the stopcock and disconnect the manometer from the stopcock to allow CSF samples to be taken.

• 6

  Close the stopcock after samples have been taken and reconnect the manometer to the stopcock to take the closing pressure reading. The zero mark of the manometer scale should be level with the LP needle. Repeat Steps 3 and 4. Disconnect the manometer and stopcock after the closing pressure has been read.