Lumbar Puncture

W18 Lumbar Puncture



Sarice L. Bassin, Thomas P. Bleck



image Before Procedure



Indications



• Suspicion of central nervous system (CNS) infection

• Suspicion of subarachnoid hemorrhage

• The need to obtain cerebrospinal fluid to diagnose other inflammatory or degenerative CNS diseases

• Reduction of cerebrospinal fluid (CSF) pressure in pseudotumor cerebri


Contraindications



• Absolute:
• Intracranial or spinous (especially intramedullary) mass (e.g., tumor, abscess). If there is concern, an imaging study should be performed before the procedure. A rapid decrease in intracranial pressure from withdrawal of CSF could precipitate herniation or worsening of spinal cord function if a mass lesion is present.

• Overlying skin infection

• Lumbar spine disease

• Relative:
• Coagulopathy and/or thrombocytopenia, because an epidural hematoma can develop at the puncture site. Fresh frozen plasma and platelets should be infused to correct hematologic abnormalities before the procedure. If a coagulopathy is discovered after the procedure, therapy should still be given, because bleeding can occur for many hours.

• If a lumbar puncture is being performed to evaluate a patient for aneurysmal subarachnoid hemorrhage, withdraw the smallest possible amount of CSF to obtain the necessary laboratory tests. Reducing the CSF pressure could precipitate rebleeding.

• Uncooperative patient


Equipment



• Lumbar puncture tray or individual components (see later)

• Chlorhexidine or povidone-iodine prepping solution

• Sterile drape with central opening

• 1% Lidocaine and a syringe with 25- and 22-gauge needles for local anesthesia

• 20- or 22-gauge spinal needle

• Manometer

• Tubes for CSF collection


image Anatomy


The site of intended puncture is generally either the L4-L5 or L5-S1 interspace. These can be determined as follows. The L3-L4 interspace can be located by drawing an imaginary line between the posterior iliac crests. This is usually the most rostral space employed, because the adult spinal cord ends at L2. Walk the fingers down the spinous processes to identify the L4-L5 and L5-S1 interspaces, and mark them on the skin. Note that when lumbar spine disease, the question of a spinal mass, or an overlying skin infection prevent the lumbar approach, a lateral cervical approach can be performed by a physician trained in this technique. In cases of difficult lumbar puncture in obese patients, bedside ultrasound can be helpful.

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Jul 7, 2016 | Posted by in CRITICAL CARE | Comments Off on Lumbar Puncture

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