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Cleansweep RN

Lumbar puncture (spinal tap) is a diagnostic and at times therapeutic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or occasionally as a treatment "therapeutic lumbar puncture" to relieve increased intracranial pressure. Although usually used for diagnostic purposes to rule out potential life-threatening conditions such as bacterial meningitis or subarachnoid hemorrhage, lumbar puncture is also sometimes performed for therapeutic reasons, such as the treatment of pseudotumor cerebri. CSF fluid analysis can also aid in the diagnosis of various other conditions, such as demyelinating diseases and carcinomatous meningitis.

Indications:

  • Suspicion of meningitis
  • Suspicion of subarachnoid hemorrhage
  • Suspicion of central nervous system diseases such as Guillain Barre Syndrome and carcinomatous meningitis
  • Therapeutic relief of pseudotumor cerebri

Contraindications:

    • Unequal pressures between the supratentorial and infratentorial compartments
    • Infected skin over the needle entry site
    • Relative contraindications to lumbar puncture are as follows:
      • Increased intracranial pressure
      • Coagulopathy
      • Brain abscess
    • Indications for brain CT scan prior to lumbar puncture include the following:
      • Patients who are older than 60 years
      • Patients who are immunocompromised
      • Patients with known CNS lesions
      • Patients who have had a seizure within 1 week of presentation
      • Patients with abnormal level of consciousness
      • Patients with focal findings on neurological examination
      • Patients with papilledema seen on physical examination with clinical suspicion of elevated ICP

Equipments:

  • Spinal or lumbar puncture tray
  • Sterile gloves
  • Antiseptic solution with skin swabs
  • Sterile drape
  • Lidocaine 1% without epinephrine
  • 3ml Syringe
  • Gauge 20 & 25 neddles
  • Spinal needles gauge 20 & 22
  • Three-way stopcock
  • Manometer
  • 4 plastic test tubes, numbered 1-4, with caps
  • Sterile dressing
  • 10 mL Syringe

Procedures:

  1. Explain the procedure, benefits, risks, complications, and alternative options to the patient or the patient's representative and obtain a signed informed consent
  2. Wearing nonsterile gloves, locate the L3-L4 interspace by palpating the right and left posterior superior iliac crests and moving the fingers medially toward the spine. Palpate that interspace (L3-L4) as well as one above (L2-L3) and one below (L4-L5) to find the widest space. Mark the entry site with a thumbnail or a marker. To help open the interlaminar spaces, the patient can be asked to practice pushing the entry site area out toward the practitioner.
  3. Open the spinal tray, change to sterile gloves, and prepare the equipment. Open the numbered plastic tubes and place them upright, assemble the stopcock on the manometer, and draw the lidocaine into the 10-mL syringe.
  4. Use the skin swabs and antiseptic solution to clean the skin in a circular fashion starting at the L3-L4 interspace and moving outward to include at least 1 interspace above and below. Just before applying the skin swabs, warn the patient that the solution is very cold, since this can be unnerving to the patient.
  5. Place a sterile drape below the patient and a fenestrated drape on the patient. Most spinal trays contain fenestrated drapes with an adhesive tape that keeps the drape in place.
  6. Use the 10-mL syringe to administer local anesthesia. Raise a skin wheal using the 25-ga needle and then switch to the longer 20-ga needle to anesthetize the deeper tissue. Insert the needle all the way to the hub, aspirate to confirm that the needle is not in a blood vessel, and then inject a small amount as the needle is withdrawn a few centimeters. Continue this process above, below, and to the sides very slightly (using the same puncture site).
  7. Stabilize the needle (20 or 22 ga) with the index fingers and advance it through the skin wheal using the thumbs. Orient the bevel parallel to the longitudinal dural fibers to increase the chances of the needle separating the fibers rather than cutting them (bevel facing up in the lateral recumbent position and facing to either side in the sitting position). Insert the needle at a slightly cephalad angle toward the umbilicus. Advance the needle slowly but smoothly. Occasionally, the practitioner feels a characteristic “pop” when the needle penetrates the dura. Otherwise, the stylet should be withdrawn after approximately 4-5 cm and observed for fluid return. If no fluid returns, replace the stylet, advance or withdraw the needle a few millimeters, and recheck for fluid return. Continue this process until fluid is successfully returned.
  8. To measure the opening pressure, the patient must be in the lateral recumbent position. After fluid returns from the needle, attach the manometer through the stopcock and note the height of the fluid column. The patient's legs should be straightened when measuring open pressure or a falsely elevated pressure will be obtained.
  9. Collect at least 10 drops of CSF in each of the 4 plastic tubes, starting with tube #1. The CSF that is in the manometer should be used (if possible) for tube #1.
  10. Replace the stylet and remove the needle. Clean off the skin preparatory solution. Apply a sterile dressing and place the patient in the supine position.

Complications:

  • Post–spinal puncture headache – This is the most common complication of lumbar puncture. It usually begins 24-48 hours after the procedure and is more common in young adults. The probable etiology is continued CSF leak from the puncture site. The headache is usually fronto-occipital and improves in the supine position.
  • Bloody tap – More than 50% of lumbar punctures have falsely present red blood cells in the CSF as a result of microtrauma caused by the spinal needle. This is an uncomplicated occurrence in healthy patients with a normal coagulation system.
  • Dry tap – Dry tap is usually a result of misplacement of the spinal needle. The most common mistake is a lateral displacement that can be easily corrected by complete withdrawal of the needle, reevaluation of the patient’s anatomy, and reinsertion in the correct place and angle.
  • Infection – Cellulitis, skin abscesses, epidural abscesses, spinal abscesses, or diskitis can result from a contaminated spinal needle.
  • Hemorrhage – Epidural, subdural, and subarachnoid hemorrhage are rare complications that might carry significant morbidity and mortality in coagulopathic patients.
  • Dysesthesia – Irritation of nerves or nerve roots by the spinal needle can cause different lower extremity dysesthesias. Withdrawing the needle without replacement of the stylet can cause aspiration of a nerve or arachnoid tissue into the epidural space. Always replace the stylet before moving the needle to prevent this complication.
  • Postdural puncture cerebral herniation – This is the most serious complication of a lumbar puncture. This is a very rare complication and debate exists in the literature regarding whether the lumbar puncture or the underlying disease process is the cause of the herniation.
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