The first part of a successful lumbar puncture is the positioning of your patient. Your patient should lay in the left lateral decubitus position with their back facing you at the edge of the bed. In this position, the patient is encouraged to curl up his shoulders and legs while arching his back "like a cat". This position will maximize the distance between the spinous processes while pulling the spinal cord superiorly (away from the LP site). It is important at this point to ensure that your patient's hips and shoulders are perpendicular to the bed, as rolling of the shoulders or hips will distort your landmarks and decreases the likelihood of a successful lumbar puncture. Hyperflexion of the neck is discouraged as it does not add to the flexion of the back.

Once the patient is in the proper position, feel the posterior superior iliac crests and imagine a line that connects the two. This line will cross the L3-L4 interspace. You may choose this space, or one above or below to use in the adult patient. You may mark this space by pressing the edge of a coin or the plastic hub of an 18 gauge needle into the skin of patient's back at this space. The skin dent in this area will help with landmarking once the patient is under the sterile drape. Once the patient is properly positioned, ensure that you have a stool for sitting and that the bed is raised to a comfortable height for you to do the procedure.

At this point you wish to put on your mask and gown, open your LP tray, and then don your sterile gloves. It is essential to prepare all the equipment on your tray before proceeding. You should not find yourself fumbling for equipment when the spinal needle is in your patient.

Stand the collection tubes in their holders and remove their caps. Draw your local anesthetic into the provided syringe with the 25 gauge needle, and assemble your manometer. Have an assistant place proviodine into the provided compartment in the tray. Once your tray is set, place the white sterile sheet along the bed, slightly under your patient (by keeping the sheet folded over your hands you will not ruin your sterile gloves). Now apply the proviodine solution to your patient's back using the provided sponge brushes. Work in circular strokes starting at the skin dent you placed on the patient's back and working concentrically outward. Do not apply so much proviodine that it runs down the patient's back as this will contaminate the lumbar puncture site. Repeat this two more times with the provided sponge sticks. Once the proviodine is placed, wipe the excess proviodine off, using the same motion with a sterile gauze.

At this point, pick up the blue sterile drape. Remove the adhesive tape cover. Place the drape on the patient so the adhesive tape is oriented towards the patient and will stick to the area of their hips. Align the hole in the drape so that it exposes the area you intend to use for the lumbar puncture. Ensure the top of the blue drape rests over your patient's hips as this drape will allow you to palpate the posterior superior iliac crest (if you need to re-landmark your LP site) as well as access the sterile field during your procedure.

You are now ready to provide the anesthesia for the lumbar puncture. Locate your chosen interspace (L3-L4 if using the posterior superior iliac crest line). Take your anesthetic (with a 25 gauge needle) and locate a point approximately two-thirds of the way down the interspace (i.e. two thirds the distance caudal to the L3 spinous process if using the L3-L4 interspace). Raise a skin bleb with your lidocaine here. Proceed to anesthetize the deeper subcutaneous structures by directing the needle towards the umbilicus. After half of the lidocaine is administered, switch your needle to the 20 gauge, 1 inch needle. Replace the needle in the area previously injected with lidocaine. With this needle, anesthetize the deeper tissues in a fan shaped distribution. This fan shape distribution is needed to anesthetize the recurrent spinal nerves that innervate this area and this will make the procedure much less painful.

After the anesthetic has been placed, it is time to proceed with the actual LP. Take out your spinal needle, and check that the stylet slides easily. When doing the LP with the provided spinal needle, ensure that the notch of the stylet (that bead on the plastic part of the stylet) is facing up to the ceiling. Position the needle at the site of the anesthetic injection (two thirds distally between the two spinous processes). Your needle should be parallel to the bed and directed towards your patient's umbilicus. Grip the proximal portion of the needle in your left hand for control and with your right hand guide the needle while holding the stylet in place. Puncturing the skin may require some force. Following the skin puncture, advance the needle through the subcutaneous tissue and into the supraspinal and intraspinal ligaments. Advance the spinal needle, while continuing to ensure the needle is parallel to the bed and aimed at the umbilicus. Occasionally, while advancing the needle, you will encounter bony resistance. If this should happen, remove your needle to the subcutaneous tissues and direct the needle slightly more cephalad. As you advance the spinal needle deeper through the ligaments repeatedly remove the stylet and check for CSF flow. In most instances as you advance the needle you feel a 'pop'. This accompanies the piercing of the ligamentum flavum and dura mater. This often signifies that you are in place. In sharp cutting needles, you may pass through the ligamentum flavum and dura mater without feeling the "pop". At this point the stylet is removed and CSF should flow freely.

If you are measuring opening pressure, the manometer is attached to the spinal needle and the stopcock opened to allow for CSF to fill the manometer. It is often helpful to have an assistant steady the top portion of the manometer, so you are free to manipulate the stopcock. The opening pressure is taken as the pressure in the column after it ceases to rise. You can expect some respiratory variation (rise and fall of the fluid meniscus with breathing). Normal opening pressures are 5-20 cm H2O in patients with relaxed neck and extended legs, or 10-28 cm H2O in those with flexed legs and back. Following the opening pressure measurement, the stopcock is turned so that the CSF drains out through the spigot and is collected in the four test tubes provided in the LP kit.

If you are not measuring opening pressure, then when CSF flow begins, collect the CSF in the sequentially labeled test tubes (i.e. tube #1 gets CSF first, tube #4 gets CSF last). You need to collect approximately one millilitre of CSF per test tube.

When the necessary CSF has been collected, the stylet is replaced into the spinal needle and the needle is withdrawn in one motion. Clean your patient's back and put the provided Band-Aid onto his/her back. Congratulations, you have just completed the lumbar puncture!