Lumbar puncture is the introduction of a hollow needle into the subarachnoid space of the lumbar portion of the spinal column to diagnose suspected infection and remove blood or pus. Cerebrospinal fluid (CSF) is completely replaced about three times a day. Although about 500 mL of CSF is formed every day, much of it is reabsorbed into the blood. There are about 120 to 150 mL of CSF in the system at any one time.

RATIONALE
● To determine or to rule out central nervous system infection;
● To determine the level of pressure in spinal column;
● To introduce drugs into the spinal canal (called an intrathecal injection).

INDICATIONS
Samples of CSF are taken for:
● Taking cell counts (a tiny number of white cells may normally be present);
● Measuring glucose and protein (also present in small quantities);
● Cytology, i.e. looking for abnormal cells;
● Immunoglobulin (antibody) studies;
● Bacterial or viral tests;
● Biochemical analysis.

CONTRAINDICATIONS
● Lumbar skin infection
● Platelet count less than 50,000/μL
● Degenerative joint disease
● Increased intracranial pressure

COMPLICATIONS
● Severe headache
● Meningitis from introducing bacteria into CSF
● Back or leg pain/paresthesia
● Accidental puncture of spinal cord
● Accidental puncture of aorta or vena cava
● Herniation of brain due to sudden decrease in pressure

PROCEDURE
Lumbar Puncture
Equipment
● Spinal tap tray
● Mask
● 22- to 23-gauge needle
● Syringe
● Manometer
● CSF specimen collection bottles
● Skin spray
● 1% lidocaine
● Povidone-iodine
● 22-gauge spinal needle
● Sterile gloves
● Fenestrated drape
● 2 × 2 gauze
● Tape

Procedure
● Position client in tripod (fetal) or lateral recumbent (fetal/child/adult) position.
● Have client clasp hands on the knees.
● Draw a line across the back between the top of the iliac crests. Locate the interspace between either L4-5 or L5 S1 (preferred) (Fig. 29.1). Mark with barrel of syringe.
● Open the spinal tray.
● Apply mask.
● Put on sterile gloves.
● Cleanse the skin 6 inches around the interspace with povidone-iodine in a circular motion.
● Cleanse the same area with 70% alcohol.
● Draw up 3 mL of 1% lidocaine.
● Assemble the manometer with the three-way stopcock.
● Inject the lidocaine at the site, raising a wheal in the skin. Inject 0.5 mL of lidocaine into the posterior spinous region.
● Insert the spinal needle with stylet in place through the skin just below the palpated spinous process. Angle about 15 degrees cephalad.
● If you hit bone or the needle meets with resistance, withdraw the needle slightly and redirect.
● Advance the needle slowly.
● After the needle is inserted a few millimeters, withdraw the stylet to see whether CSF is present. You may hear a popping sound when the needle penetrates the dura.
● Advance the needle 1 to 2 mm farther.
● Remove the stylet.
● Attach the manometer to the hub of the inserted needle. Note the level of pressure on the manometer.
● Open the stopcock to allow the CSF to flow into the test tubes. CSF collection usually takes 5 to 10 seconds. Do not attempt to aspirate CSF with a syringe.
● If blood returns, remove needle and discard.
● Repeat procedure with fresh needle.
● Remeasure level of pressure. Do not withdraw CSF if pressure is significantly different.
● Label the tubes (See table below).
● When enough CSF has been obtained, replace the stylet and remove the needle.
● Spray the skin.
● Cover the insertion site with a 2 × 2 pressure dressing and leave in place for 2 hours.
● Send tubes to laboratory within 2 hours for analysis (See table below). Do not refrigerate the tubes.

Labeling Tubes

TUBE NO	PURPOSE OF TEST
1. Biochemistry	Glucose, protein
2. Bacteriology	Varying shades of pink to coral red; Gram stain, culture (bacterial); Indicate whether the following are needed (Fungal culture, TB culture, Viral culture)
3. Hematology	Cell count, differential
4. Optional	VDRL,India ink (fungal), Cytology, Myelin basic protein, Oligoclonal bands

TB, tuberculosis; VDRL, Venereal Disease Research Laboratory.

Normal Cerebrospinal Fluid

TEST	NORMAL VALUE	INDICATION
Opening pressure	50 to 200 mm H2O	No intracranial pressure, No obstruction
WBC glucose	<5/mm3 50% to 80% of serum glucose	No infection, No hypoglycemia or hyperglycemia
Protein	15 to 45 mg/dL	No hemorrhage, No tumors, Nontraumatic tap
Color	Clear and colorless	No bacteria, WBCs, or bleeding
RBC	<20	Nontraumatic tap

WBC, white blood cell; RBC, red blood cell.

Abnormal Cerebrospinal Fluid Values

TEST	NORMAL	ABNORMAL	INDICATION
Appearance	Clear	Cloudy, Bloody	Infection, Hemorrhage, obstruction, or traumatic tap
Appearance		Brown, yellow, orange	Elevated protein, RBC hemolysis present for ≥3 days
Protein	15 to 45 mg/dL	Increase	Tumors, trauma, hemorrhage, diabetes mellitus, polyneuritis, blood in CSF
Protein		Decrease	Rapid CSF production
Gamma globulin	3% to 12%	Increase	Multiple sclerosis, neurosyphilis, Guillain-Barré syndrome
Glucose	50% to 80%	Increase	Systemic hyperglycemia
Glucose		Decrease	Systemic hypoglycemia, Bacterial or fungal infection, meningitis, mumps
Cell count	0 to 5 WBCs, No RBCs	Increase	Active disease, meningitis, tumor, abscess, infarction, multiple sclerosis
Cell count		RBCs present	Hemorrhage, traumatic tap
VRDL	Nonreactive	Positive	Neurosyphilis
Chloride	118 to 130 mEq	Decrease	Meningitis, TB
Gram stain	Negative	Gram-positive or -negative organisms	Bacterial meningitis

RBC, red blood cell; CSF, cerebrospinal fluid; WBC, white blood cell; VDRL,Venereal Disease Research
Laboratory; TB, tuberculosis.

Nursing considerations
● Lumbar puncture is a strict aseptic technique requiring full sterile procedures.
● Encourage patients to drink well before and after the procedure.
● Positioned the patient carefully, laying on one side in a curled up position with the lumbar spine exposed (knees drawn up to the chest). Moving the patient’s back closer to the edge of the bed will make access to the lumbar spine easier. Support the patient in this position throughout the procedure.
● A small local sterile dressing is applied to the spinal site after removal of the needle.
● Headache is a common complaint following lumbar puncture. The patient should lay flat for 6-12 hours afterwards, as sitting up may make any headache worse.
● In myelograms, the patient’s head should be kept raised for up to 24 hours afterwards to prevent contrast medium in the spinal canal from entering the skull. This may caused seizures if it passes around the brain (Blows, 2002).
● Have the client avoid strenuous activity for first 24 hours after procedure.

Post Procedure Care
● Monitor vital signs and neurological status.
● Assess LP site for bleeding or CSF leak every 15 minutes for one hour. Maintain patient in supine position for 1 hour or as ordered.
● Assess for presence of headache and nausea. Administer analgesic and antiemetic as ordered.
● Report to physician of any significant changes in vital signs or neurological status, including pupillary changes, swelling, bleeding or CSF leak at LP site, tingling or loss of sensation/function of lower limbs, changes in bowel or bladder control, headache or nuchal pain or rigidity.

BIBLIOGRAPHY
● American Thoracic Society. Lumbar puncture; 2000. www.thoracic.org.
● Fischbach F. A manual of Laboratory and Diagnostic Tests. 6th ed. Philadelphia, PA: Lippincott; 2001.
● Intermed Communications, Inc. Diagnostics: An A-Z Guide to Laboratory Tests. Springhouse, PA: Intermed Communications, Inc; 2000.
● Neurology. Protocol for lumbar puncture; 2002. http://www.neuro.nwu.edu.

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