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Procedure ⬇

  1. Place the patient in a side-lying position with the head flexed onto the chest and knees drawn up to, but not compressing, the abdomen to “bow” the back. This position helps to increase the space between the lower lumbar vertebrae so that the spinal needle can be inserted more easily between the spinal processes. However, a sitting position with the head flexed to the chest can be used. The patient is helped to relax and instructed to breathe slowly and deeply with their mouth open.

  2. Select the puncture site, usually between L4 and L5 or lower. There is a small bony landmark at the L5–S1 interspace that helps to locate the puncture site. The site is thoroughly cleansed with an antiseptic solution, and the surrounding area is draped with sterile towels in such a way that the drapes do not obscure important landmarks (Figure 5.2).

  3. Inject a local anesthetic slowly into the dermis around the intended puncture site.

  4. Insert a spinal needle with stylet into the midline between the spines of the lumbar space and slowly advance until it enters the subarachnoid space. The patient may feel the entry as a “pop” of the needle through the dura mater. Once this happens, the patient can be helped to straighten their legs slowly to relieve abdominal compression.

  5. Remove the stylet with the needle remaining in the subarachnoid space and attach a pressure manometer to the needle to record the opening CSF pressure.

  6. Remove a specimen consisting of up to 20 mL of CSF. Take up to four samples of 2–3 mL each, place in separate sterile screw-top tubes, and label with the patient’s name, date and time of collection, and test(s) ordered. Label the tubes sequentially: tube 1 is used for chemistry and serology; tube 2 is used for microbiology studies; tube 3 is used for hematology cell counts; and tube 4 is used for special studies such as cryptococcal antigens, syphilis testing (Venereal Disease Research Laboratory), protein electrophoresis, and other immunologic studies. A closing pressure reading may be taken before the needle is withdrawn. In cases of increased ICP, no more than 2 mL is withdrawn because of the risk that the brain stem may shift.

  7. Remove the needle and apply a small sterile dressing to the puncture site.

  8. Send the correctly labeled specimens of CSF immediately to the laboratory, where they should be given to laboratory personnel with specific instructions regarding the testing. CSF samples should never be placed in the refrigerator because refrigeration alters the results of bacteriologic and fungal studies. Analysis should be started immediately. If viral studies are to be performed, a portion of the specimen should be frozen.

  9. Record procedure start and completion times, patient’s status, CSF appearance, and CSF pressure readings.

Procedural Alert

  1. If the opening pressure is more than 200 mm H2O in a relaxed patient, no more than 2 mL of CSF should be withdrawn.

  2. If the initial pressure is normal, Queckenstedt test may be done. (This test is not done if a CNS tumor is suspected.) In this test, pressure is placed on both jugular veins to occlude them temporarily and to produce an acute rise in CSF pressure. Normally, pressure rapidly returns to average levels after jugular vein occlusion is removed. Total or partial spinal fluid blockage is diagnosed if the lumbar pressure fails to rise when both jugular veins are compressed or if the pressure requires more than 20 seconds to fall after compression is released.

Interventions ⬆

Pretest Patient Care

  1. Explain the purpose, benefits, and risks of lumbar puncture and explain tests to be performed on the CSF specimen; present a step-by-step description of the actual procedure. Obtain an informed consent, if possible. Emphasize the need for patient cooperation. Assess for contraindications or impediments such as arthritis. Sedation or analgesia may be used.

  2. Help the patient to relax by having them breathe slowly and deeply. The patient must refrain from breath-holding, straining, moving, and talking during the procedure.

  3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed for abnormal outcomes and complications such as paralysis (or progression of paralysis, as with spinal tumor), hematoma, meningitis, asphyxiation of infants due to tracheal obstruction from pushing the head forward, and infection.

  2. Observe for neurologic changes such as altered level of consciousness, change of pupils, change in temperature, increased blood pressure, irritability, and numbness and tingling sensations, especially in the lower extremities.

  3. If headache occurs, administer analgesic agents as ordered. If severe headache persists, an epidural blood patch may need to be done, in which a small amount of the patient’s own blood is introduced into the epidural space at the same level that the canal was previously entered.

  4. Check the puncture site for leakage.

  5. Document the procedure completion and any problems encountered or complaints voiced by the patient.

  6. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Clinical Alert

  1. Extreme caution should be used when performing lumbar puncture in the following cases:

    1. If ICP is elevated, especially in the presence of papilledema or split cranial sutures. However, with some cases of increased ICP, such as with a coma, intracranial bleeding, or suspected meningitis, the need to establish a diagnosis is absolutely essential and outweighs the risks of the procedure.

    2. If ICP is from a suspected mass lesion. To reduce the risk for brain herniation, a less invasive procedure such as a CT scan or magnetic resonance imaging should be done.

  2. Contraindications to lumbar puncture include the following conditions:

    1. Suspected epidural infection

    2. Infection or severe dermatologic disease in the lumbar area, which may be introduced into the spinal canal

    3. Severe psychiatric or neurotic problems

    4. Chronic back pain

    5. History of stroke, unless intracerebral hemorrhage is ruled out by CT scan

    6. Anatomic malformations, scarring in puncture site areas, or previous spinal surgery at the site

  3. If there is CSF leakage at the puncture site, notify the healthcare provider immediately and document findings.

  4. Follow standard precautions (see Appendix A) when handling CSF specimens.