++
Lumbar puncture is considered the gold standard diagnostic procedure to
assist clinicians with the evaluation for subarachnoid hemorrhage, meningitis,
and other neurologic conditions. Anxiolytics, such as benzodiazepines,
may be administered to improve patient comfort, relaxation, and
cooperation. Contraindications to lumbar puncture are listed in Table 169-1.
++
++
If an anxiolytic is used, a short-acting agent should be administered
to avoid clouding subsequent clinical assessment. Antiseptic technique should
be strictly observed. The site should be scrubbed with povidone-iodine
and allowed to dry thoroughly to avoid introduction of the chemical
by the lumbar puncture and the subsequent production of chemical
arachnoiditis.
++
In adults, a transverse line drawn between the iliac crests crosses
the spine at the L4 spinous process. The L4-L5 interspace is the
most commonly used interspace for lumbar puncture, although one
can also select the L3-L4 interspace. The L4-L5 interspace should
be palpated while the patient is curled as tightly as possible in
a fetal position. Alternatively, the patient may be seated on the
edge of a bed or cart leaning over a tray stand. This latter technique
is particularly useful when landmarks are uncertain due to body
habitus.
++
A 31/2-in. atraumatic 22-gauge needle
ideally should be used in adults. Use of a needle larger than 20-gauge
may double the incidence of post–lumbar puncture headache
compared with a smaller needle. The use of an atraumatic or pencil-point
needle (such as a Whitacre or Sprotte needle) is associated with
fewer post–lumbar puncture headaches than a conventional
cutting needle1,2 (Figure 169-1).
Also, a smaller needle size is associated with reduced frequency
of post–lumbar puncture headaches.1
++
++
The steps for lumbar puncture are described in the video Lumbar
Puncture Decubitus Position.
++
Assemble all equipment. Then properly position the patient and
identify the patient’s L4-L5 interspace. Now put on your
sterile gown, mask, and gloves. Next, apply povidone-iodine to the
area and let dry. Apply sterile drapes. Anesthetize the skin with
1% lidocaine by raising a skin bleb, then directing the
needle toward the umbilicus, and injecting the anesthetic in a fan-shaped
area around ...