PROCEDURE 96 A lumbar puncture is performed for access to the subarachnoid space to obtain a cerebrospinal fluid sample, measure cerebrospinal fluid pressure, drain cerebrospinal fluid, infuse medications or contrast agents, or place a cerebrospinal fluid drainage catheter.1–3,7 • Knowledge of neuroanatomy and physiology is needed. • A lumbar puncture (LP) at L3-L4 or L4-L5 in an adult is usually performed to obtain a cerebrospinal fluid (CSF) sample.18 • Indications for lumbar puncture are as follows: • Contraindications for lumbar punctures are as follows5,18,28,29: • The preferred positioning for a lumbar puncture is lateral decubitus with the neck, hips, and knees flexed (knees to chest); the axis of the hips vertical; the back close to the edge of the bed; head of the bed flat; and no more than a small pillow under the head (see Figs. 95-1 and 96-1).19 If the lumbar puncture is not successful in this position, or if the patient cannot tolerate this position, the patient may also be positioned sitting on the side of the bed, leaning over a bedside table or stand.19,21,23,29 This procedure may also be performed with fluoroscopy for patients with marked obesity or spinal deformities. Optimal positioning is necessary to avoid the risk for a “dry tap” or an unsuccessful puncture attempt. Repeated attempts at puncture increase the risk for infection and patient discomfort.3,18 • Proper positioning for a lumbar puncture widens the interspinous process space and facilitates the passage of the needle.2,3,5,6 • Sterile gloves, caps, masks with eye shield, and sterile gowns • Manometer with a three-way stopcock • Lidocaine, 1% to 2% (without epinephrine) • 18-, 20-, 22-, and 25-gauge needles • 18-, 20-, or 22-gauge spinal needles • Four consecutively numbered, capped test tubes • Adhesive strip or sterile dressing supplies • Glucometer/phlebotomy supplies for concurrent testing of serum or whole blood glucose Additional equipment, as needed, includes the following:
Lumbar Puncture (Assist)
PREREQUISITE NURSING KNOWLEDGE
Cerebrospinal fluid analysis may be indicated in the differential diagnosis of subarachnoid hemorrhage, central nervous system (CNS) infection, CNS autoimmune processes, and some malignant diseases.4,5,18,28
Therapeutically, a lumbar puncture may be used to treat hydrocephalus, cerebrospinal fluid fistulas, and pseudotumor cerebri; to deliver medications or contrast material into the subarachnoid space; or to access the subarachnoid space for placement of a lumbar subarachnoid drain.4,5,18,28
Lumbar punctures are contraindicated if the patient has a known or suspected intracranial mass or elevated intracranial pressure (ICP), noncommunicating hydrocephalus, or infection in the region to be used for lumbar puncture or is coagulopathic or therapeutically anticoagulated. If CSF analysis is necessary, the patient may need pretreatment with fresh frozen plasma, platelets, cryoprecipitate, or the specific factor needed to correct a hematologic abnormality.5,18,28,29
Lumbar punctures are cautioned against in patients suspected of aneurysmal subarachnoid hemorrhage and in patients with complete spinal blocks. In such cases, a lumbar puncture may be performed if the computed tomographic (CT) scan of the patient’s head does not indicate signs of increased ICP, such as significant cerebral swelling, hematoma, intracranial tissue shifts, or herniation.5,18,28,29
Brain herniation may occur after punctures in the presence of an intracranial mass lesion or increased ICP.3,18
EQUIPMENT
PATIENT AND FAMILY EDUCATION
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