Lumbar Puncture

by | Apr 24, 2024 | Nurse Article | 0 comments

Lumbar Puncture

A lumbar puncture (L.P.; spinal tap; spinal puncture) is the insertion of a needle into the lumbar region of the spine, in such a manner that the needle enters the lumbar arachnoid space of the spinal canal below the level of the spinal cord, so that the cerebrospinal fluid (C.S.F) can be withdrawn or a substance can be therapeutically or diagnostically injected.

The cerebrospinal fluid is formed through the choroid villi, in each of the four ventricles of the brain and it circulates freely through the ventricles, the subarachnoid space and the central canal of the spinal cord. It is then absorbed into the venous circulation via superior sagittal sinus. By this arrangement, the delicate nerve matter of the brain and the spinal cord lies between the two layers of the fluid, the internal layer of the fluid being contained in the ventricles of the brain and in the central of the spinal cord, and the external layer of fluid in the subarachnoid spaces surrounds the brain and spinal cord.

Purpose of Lumbar Puncture

1. To administer spinal anaesthesia before surgery in the lower half of the body.

2. To administer medication into the spinal canal as in the case of meningitis.

3. To remove fluid (CSF, blood pus etc) contained in the subarachnoid space, thereby reduce the intracranial pressure if it is dangerously high.

4. To remove a sample of CSF for laboratory examinations in order to diagnose diseases.

5. To measure the pressure of CSF and to determine whether the lumbar subarachnoid space is in communication with the ventricles of brain.

6. To remove CSF and to replace it with air, oxygen or radio-opaque substances for diagnostic X-rays (pneumo-encephalography, myelography etc) in order to locate tumors or other brain disorders.


1. Injury to the spinal cord and spinal nerves.

2.Infection introduced into the spinal cavity which may give rise to meningitis.

3. Leakage of CSF through the puncture site and lowering the intra-cranial pressure and may cause post puncture headaches.

4. Damages to the intervertebral disc.

5. Local pain, oedema and haematoma at the puncture site.

6. Temperature elevation.

7. Rapid reduction in the intracranial pressure cause by the removal of CSF can cause herniation of the brain structures into the foramen magnum. This in turn causes pressure on the vital centres in the medulla causing respiratory failure and sudden death.

8. Pain radiating to the thighs due to trauma of the spinal nerves.


Site of Lumbar Puncture and the Positioning of the client

Since the spinal cord ends at the level of the first lumbar vertebra and the subarachnoid space extends up to the second sacral vertebra, any site between these two points may be used for the puncture of the spine. In adults the site of the lumbar puncture is usually between the second and third or fourth and fifth lumbar vertebrae. In small children and infants, the site is still lower because the spinal cord extends up to the third lumbar vertebra. These sites are safe to prevent injury to the spinal cord.

The client is placed in a sidelying position (right or left according to the doctor’s convenience) at the edge of the table or bed. The client’s body should be in foetal attitude (‘C’ shaped) with full flexion of the spine. The back should be vertical to the bed and with no lateral flexion of the spine.  The client is asked to draw both knee up towards the chin. The head and neck are flexed and brought towards the chest. In order to maintain this position, the client may keep both his hands between the knees. In this position the intervertebral spaces are widened and the needle can be easily inserted. If the client is not able to maintain this position, the nurse helps him. The nurse stands in front of the client and keeps one hand behind the knees and the other hand behind the neck and tries to bring the client into the desired position.

Preparation of Articles

A sterile tray containing:

1. L.P. needles – 2 sizes with their stiletto

2. Sponge holding forceps

3. Syringe (5 ml) with needles to give local anaesthesia.

4. Small bowl to take cleaning lotion

5. Specimen bottles

6. Cotton balls, gauze pieces and cotton pads

7. Gloves, gown and masks

8. Dressing towels or slit

9. Three way adaptor, manometer and tubing to measure the pressure of the CSF

An unsterile tray containing:

1. Mackintosh and towel

2. Kidney tray and paper bag

3. Spirit, iodine, tr. Benzoin etc

4. Lignocaine 2 percent

5. Sterile normal saline to fill in the manometer

6. Adhesive plaster and scissors



The client is positioned correctly. The skin is prepared as for a surgical procedure. Under local anaesthesia, the needle is inserted between the second and third or between the third and fourth lumbar vertebrae. The position can be determined by drawing a vertical line from the top of the iliac crest to the spine. This crosses the spine at the 4th lumbar spine or L2 to L3 interspace. One interspace cranially at L3 to L4 is selected. When the needle has entered the subarachnoid space, the stilette is removed and the 3 way adaptor with the manometer filled with normal saline is attached. The pressure is noted. Normally the CSF oscillates in the manometer readily responding to coughing, deep breathing etc. the client is asked to relax as much as possible to get a stabilized pressure. Normally it is 6 to 13 mm Hg or 80 to 180 mm of water. About 2 to 3 ml of CSF is allowed to drip into each of 3 sterile test tubes and then the needle is withdrawn. The puncture wound is sealed.



1. Since any infection introduced into the spinal cavity would be fatal for the client, strict aseptic techniques are to be followed. The doctor scrubs the hands thoroughly, put on gown, gloves, etc., to maintain asepsis. All articles used for the lumbar puncture should be autoclaved.

2. The client should be placed in a position that will widen the intervertebral space. Usually a sidelying person with the knees drawn to the chin or a sitting position with the head and neck flexed is maintained during the procedure.

3. Uncooperative clients and children are to be restrained during the procedure. The clients are to be warned to remain still during the procedure to prevent injury to the spinal cord or nerves.

4. The client should be placed near the edge of the bed or table for the convenience of the doctor. The client’s back should be at right angles to the bed. If the bed sags, place a fracture board below the mattress to prevent lateral flexion of the spine.

5. The L.P. needles should be sharp, small in size and not curved.

6. The flow of CSF vary in different conditions; when the intracranial pressure is high, the fluid may spurt out in jets; when the tension is low as in case of dehydration, the fluid may come out only on straining or coughing.

7. The pressure reading of the CSF is taken when the client is relaxed and the fluid level remains fairly constant in the manometer. The CSF will oscillate in the manometer as pressure is applied (during coughing, straining, and deep breathing). Therefore, the client is asked to relax by breathing slowly through the mouth. The pressure may be high in cases of cerebral oedema and cerebral haemorrhage. It may be ventricles of brain and the spinal canal and in case of dehydration.

8. If a ‘Queckenstedt’s test’ is to be carried out during the procedure the nurse is asked to compress the jugular vein first on one side, then on the other side and finally on both sides at the same time. When normal, there is a sharp rise in the pressure followed by a fall as the compression is released. If the test is negative, one must conclude that a block exists between the ventricles of the brain and the spinal canal which might be caused by spinal tumor, dislocation or fracture of the vertebrae etc. blockage of the spinal canal or thrombosis of the jugular vein will result in the absence of rise or only a sluggish rise and fall in the manometer readings. In order to compress the vein, the nurse spreads her fingers on either sides of the neck, lateral to the trachea and the pressure is applied without compressing the trachea.

The Queckenstedt’s test is contraindicated in the presence of intracranial diseases particularly in the presence of intracranial pressure and intracranial haemorrhage.

9. If the nurse has to hold the manometer tube for recording the pressure she should hold it above the point where the doctor’s hand need to come in contact with it, since her hands are not sterile.

10. After the lumbar procedure, the client should lie flat on the bed. If the client develops headache, he should not be allowed to sit up in bed even for a short period. Foot end may be raised to fill up the ventricles with the CSF. The client develops headache after the lumbar puncture due to reduced intracranial pressure as a result of fluid removed from the spinal cavity. It may also develop due to the leakage of CSF from the subarachnoid space through the puncture wound. Therefore, the nurse should watch the puncture site for leakage of fluid.

11. The CSF collected should be sent to the laboratory without any delay. If it is allowed to stand, changes will take place in the fluid and we will get only a false result. The CSF is tested for the following:

a. Physical findings, color and appearance: normally the CSF is crystal clear. Turbulence indicates infection (e.g., meningitis), blood indicates haemorrhage. (the initial appearance of the blood with the spinal fluid may be due to puncture of the capillaries at the site of the puncture).

b. Cell count: normally there is no RBC found in CSF. Presence of RBC indicates haemorrhage in the CNS; increased number of WBC (above 5cmm) indicates infection somewhere in the CNS. Tuberculosis and viral infections may cause an increase in lymphocytes, while pyogenic infection may cause increase in polymorphonuclear leckocytes.

c. Sugar content: bacterial infection such a tuberculous meningitis often lower the sugar content from the normal level of 40 to 60 mg. per 100 ml.
d. Chloride level: bacterial infection also reduces the chloride level from the normal of 720 to 750 mg per 100 ml.

e. Protein level: in the presence of degenerative diseases and brain tumor, the protein content is increased from the normal level of 30 to 50 mg per 100 ml.

f. Serological test: serological test for syphilis may be positive in the CSF even the blood serology is negative.

13. Usually the CSF is collected in two or three containers. The first specimen may contain a tinge of blood due to the capillary bleeding at the site of the puncture. The specimen bottles should be numbered 1, 2, 3, as the specimens are collected.

14. The amount of CSF withdrawn is equal to the volume of fluid to be introduced or is sufficient for the laboratory investigations planned. The CSF removed may be used as diluent to dissolve the drugs.

15. Drugs to be injected must be warmed to body temperature and it should be injected very slowly.

16. At the end of the procedure, the puncture site is sealed to prevent leakage of fluid from the spinal cavity and infection entering into the spinal cavity.
The client’s vital signs should be checked frequently during and after the procedure to detect the early signs of complications.

Preparation of the Client

1. Explain the procedure to the client to relieve his anxiety and fear. Explain how he can cooperate in the procedure. Teach the client how he should maintain the desired position during the procedure. The client should understand that the needle inserted will be well below the end of the spinal cord, so that there is no danger of injury to the spinal cord. The explanations are given in simple language.

2. Warm the client that any movement during the procedure may cause injury to the spinal cord and its nerves. So he should lie still during the procedure.

3. Check the B.P. pulse and respiration before sending the client to the operation room and record the finding on the nurse’s record for the further reference.

4. Prepare the skin as for a surgical procedure. Shave and clean the area thoroughly with soap and water. Again the skin is disinfected with spirit and iodine just before doing the spinal puncture.

5. Put on clean and loose garments.

6. Arrange the articles that are necessary for lumbar puncture at the bedside table. Remove the unnecessary articles from the bedside. Arrange the articles for the convenience of the doctor.

7. Fanfold the top bedding well below the hips and cover the shoulders with a bath blanket. Expose only the site of the spinal puncture.

8. Fold back the upper garments above the waist line and the lower garments well the below the hip exposing the site.

9. Protect the bed with mackintosh and towel.

10. Provide a stool for the doctor to sit continuously during the procedure.

11. The nurse should stand near the client throughout the procedure observing his general condition and helping him to maintain the desired position. If the client can not the maintain the desired position by himself, the nurse helps him. Instruct the client to breathe quietly and not talk or cough during the procedure unless it is asked by the doctor.

After Care of the Client

1. As soon as the needle is withdrawn, seal the puncture site to prevent leakage of CSF.

2. Place the client comfortably on the bed in a supine position. He should be asked to lie down flat on bed for 12 to 24 hours.

3. If the client develops post puncture headache, the following precautions are taken:

a. Darken the room

b. Given plenty of oral fluids to re-establish the CSF level

c. Administer analgesics

d. Raise the foot end of the bed

4. The client should be watched constantly for several hours after L.P. Any changes in the client’s general condition should be reported immediately. Watch for client’s color, pulse, respiration, blood pressure and other signs of complications such as nausea, vomiting, headache etc.

5. Record the procedure on the client’s chart with date and time. Record the amount and character of the fluid withdrawn, the pressure of the CSF measured, client’s tolerance to the procedure, any changes in the client’s general conditions, any untoward reaction such as nausea, vomiting, and headache etc, developed in the post procedure period.

6. The specimens of CSF collected should be sent to the laboratory without any delay with proper label and requisition form.

7. If there are no complications observed, the client may be allowed to be upright after 8 to 12 hours.