Lumbar Puncture

Common Diagnostic procedures in
Prepared by :
Maha Hmeidan Nahal
Common Diagnostic procedures
in pediatrics
Lumbar puncture
Arterial Blood Gases
Lumbar Puncture
Lumbar Puncture
Lumbar Puncture - involves withdrawing
cerebrospinal fluid by the insertion of a hollow
needle into the lumbar subarachnoid space”.
Cerebral Spinal Fluid – Clear, lymph-like fluid
that fills the entire subarachnoid space and
surrounds and protects the brain.
Indications for Lumbar
Primary indication for emergent spinal
tap is possibility of CNS infection
The second indication for an emergent
spinal puncture is a suspected
spontaneous subarachnoid
Diagnosis usually made by CT scan or by
blood in CSF.
Initial presentation: CT 92-98% accurate
Later than 24 hr presentation: 76% accurate
Infectious Indications
Fever of unknown origin
Children 1month to 3yrs:
fever, irritability, and
Over age 3yrs: nuchal
rigidity, Kerning's sign.
Petechial rash in a febrile
Contraindications for LP
presence of infection in the tissues near the puncture
Increased ICP--The presence of papilledema, retinal
A sudden drop in intraspinal pressure by rapid
release of cerebrospinal fluid (CSF) may cause fatal
Bleeding diathesis: A platelet count is desirable
before LP.
Spinal needle
Three-way stopcock
3 specimen tubes
Local anesthesia
Plaster dressing
Sterile towel
Equipment required
Three sterile specimen bottles: should be
labeled 1, 2 and 3. The first specimen, which
may be bloodstained due to needle trauma,
should go into the first bottle. This will assist
the laboratory to differentiate between blood
due to procedure trauma and that due to
Subarachnoid hemorrhage.
Performed with the
patient in the lateral
recumbent position.
A line connecting the
posterior superior iliac
crest will intersect the
midline at approx. the
L4 spinous process.
Spinal needles entering
the subarachnoid space
at this point are well
below the termination of
the spinal cord.
LP in infant may be
performed at the L4 to L5
or L5 to S1 interspace
LP in older children and in
adults may be performed
from L2 to L3 interspace to
the L5 to S1 interspace.
Position the patient:
Generally performed in
the lateral decubitus
A pillow is placed under
the head to keep it in the
same plane as the spine.
Lower back should be
arched toward
Almost all patients are afraid of an LP.
Explaining the procedure in advance
and discussing each step aids in
reducing anxiety.
Inquire about allergies to anesthetics.
Informed consent.
Sterile gloves MUST be used.
Wash back with antiseptic solution.
Sterile towel under hips.
The skin and deeper subcutaneous
tissue are infiltrated with local
Warn patient of transient discomfort of
The patient should be told to report any
pain and should be informed that he or
she will feel some pressure.
The needle is placed into the skin in the
midline parallel to the bed.
The needle is held with both thumbs
and index fingers.
The ligaments offer resistance to the needle, and a
“pop” is often felt as they are penetrated.
Clear fluid will flow from the needle when the
subarachnoid space has been penetrated.
If bone is encountered,
withdrawal into
subcutaneous tissue
and redirect.
Attach a manometer
and record opening
Turn stopcock and
collect fluid.
Withdrawal needle and
place a dressing.
Tube 1 is used for determining protein
and glucose
Tube 2 is used for microbiologic and
cytologic studies
Tube 3 is for cell counts and serologic
tests for syphilis
The Traumatic Tap
It should not be difficult to distinguish
between subarachnoid hemorrhage and
a traumatic tap.
In traumatic taps, the fluid generally
clears between 1st and 3rd tubes.
If CSF is not crystal clear, a pathologic
condition of the CNS should be suspected
 Compare fluid to water
 Fluid may be clear with as many as 400
RBCs/mm3 and 200 WBCs/mm3
WBC counts over 5 cells/mm3 should be taken to
indicate the presence of pathologic condition
Neutrophilic pleocytosis (increase in number) is
commonly associated with bacterial infections or
early stages of viral infections, tuberculosis, or
Eosinophils are most commonly represent a
parasite infestation.
Eosinophils have also been reported in cases of
subarachnoid hemorrhage, lymphoma, Hodgkin’s
disease, brucellosis, fungal meningitis,
mycoplasma pneumonia infection, measles, and
many other infectious disease.
Normal CSF RBCs are less than 10/mm3.
 Counts that are otherwise unexplained
may be due to a traumatic tap.
 Herpes simplex virus encephalitis may
elevate the CSF RBC count in many
Low CSF glucose concentration indicates
increased glucose use in the brain and the
spinal cord.
 The normal range of CSF glucose is
between 50 and 80 mg/dl
 60-70% of serum glucose concentration
 Only low concentrations of glucose are
Low CSF Glucose Syndromes
Bacterial meningitis
Tuberculous meningitis
Chemical meningitis
Fungal meningitis
Subarachnoid meningitis
Mumps meningitis
Herpes simplex
Amebic meningitis
Increase in CSF total protein levels are a
nonspecific abnormality associated with
many disease states.
 Levels > 500mg/dl are uncommon and are
seen mainly in meningitis, in subarachnoid
bleeding, and with spinal tumors.
CSF Analysis with
Bacterial Infections
While the culture is pending, one may suspect a
bacterial infection in the presence of an elevated
opening pressure and a marked pleocytosis
ranging between 500 and 20,000 WBCs/mm3.
The differential count is usually chiefly neutrophils.
A count above 1000 cells/mm3 seldom occurs in
viral infections.
CSF Analysis with
Bacterial Infections
CSF glucose levels less than 40 mg/dl or
less than 50% of a simultaneous blood
glucose level should raise the question of
bacterial meningitis.
 The CSF protein content in bacterial
meningitis ranges from 500 to 1500 mg/dl.
CSF Analysis with
Viral Studies
The organisms most commonly isolated in
viral meningitis are enteroviruses and
Enteroviruses: summer and fall
 Mumps: winter and spring
CSF Analysis with
Viral Studies
WBC count in viral meningitis and
encephalitis usually: 10 to 1000 cells/mm3.
 The differential count is predominantly
lymphocytic and mononuclear in type.
 Protein levels are usually mildly elevated
Headache After
Lumbar Puncture
Most common
Occurs 5-30% of all
spinal taps
Usually starts up to
48 hours after to
Usually lasts 1-2
days (occas 14 days)
Headache After Lumbar Puncture
Usually begins within minutes after arising
and resolves with recumbent position.
 Pain is mild to incapacitating and is usually
cervical and sub-occipital, but may involve
the shoulders and the entire cranium.
 Caused by leaking of fluid through dural
puncture site.
Headache After Lumbar Puncture
Incidence is higher in younger patients and
females, and those with headache history.
 Treatment: barbiturates, fluids (500mg in 2
ml NS IV push) more common 500mg in 2
L over 1 hr.
 Blood patch by anesthesia if no
Pain down one leg
during the procedure
The spinal needle may have
touched a dorsal nerve root
Headache may
develop up to 24 hrs
following procedure
Removal of cerebrospinal fluid a) Reassure patient
b) Relieve by lying flat
c) Encourage increased
fluid intake
d) Take analgesia
b) Position required a)
Insertion of needle to
a) Leakage of cerebro- spinal
Deterioration in
neurological status
Presence of space occupying
lesion in the brain not
a. Reposition the needle.
b. Reassure the patient
a) Reassure patient
b) Lie flat
c) Take analgesia
a) No further action required
b) Report immediately if
associated with other
Need medical assistance
Recommendations for
1- prepare
all equipments before starting the
2- explain procedure to family , why , how the
procedure done.
3- keep child in sterile field as possible.
4- sending all samples to lab after procedure
5- explain to family how to care of child after
procedure to decrease potential problems.
Arterial Blood Gases
Arterial blood gases: are measured to assess a child or a
client’s oxygenation, ventilation, and acid-base balance.
The blood sample is easily, although often painfully,
obtained from an artery and is analyzed for:
-arterial blood pH
- partial pressure of oxygen (PaO2)
- partial pressure of carbon dioxide (PaCO2)
-arterial oxygen saturation (SaO2).
- Rate and depth of respirations can affect the results of an
ABG sample.
Arterial Blood Gases
-Assess the type of symptom and lung sounds that require
an arterial blood gas (ABG) sample.
- Signs and symptoms may include:
- Dyspnea /cyanosis
- sudden change in respiratory rate or pattern
- unequal breath sounds
- unequal chest expansion
-change in level of consciousness
- and increased work of breathing.
Arterial Blood Gases
-Assess collateral blood flow by performing Allen’s
test to choose a site for ABG sample.
- Assess tissue surrounding artery to avoid sites of
previous punctures and proximity to veins.
-Assess baseline or most recent ABG for child to
compare with current status.
-Assess child (older child) knowledge about the
procedure of obtaining an ABG sample to ensure
cooperation and reduce anxiety.
Equipment Needed
• Heparinized
syringe with cap, 3 ml (check agency policy
for heparin solution use) Heparin 1:1000 solution
• A 23- or 25-gauge needle
•Povidone-iodine and alcohol swabs
• Gauze pad
• Cup with crushed ice
• Label with date, time, and client’s name
• Laboratory requisition
• Disposable gloves
- Prepare the heparinized syringe before going into the client’s room.
- Remember that superficial arteries are at the distal ends of
- Be sure to calmly warn the client before you insert the needle so he
does not pull back his hand.
- A rolled towel placed under the client’s wrist helps him to relax his
hand and allows easier access to the artery.
- Never pull back on the plunger of the syringe while sampling
arterial blood.
-Bring a cup of ice into the room to have available to transport the
Arterial Blood Gases
Allen's Test :
procedure that assesses the circulation of the radial ,ulner,
or brachial arteries .Using your fingers , apply occlusive
pressure to both the ulner and radial arteries causing
blanshing of the hand , then release finger pressure from
the ulner artery should lead to return of the normal red
color of the hand speeking of patency of ulner artery and
vic versa .
Blood Gas Sampling Errors
- Air or air bubbles left in the blood gas sample.
-Delay in icing or analyzing the blood gas sample.
- Excess heparin left in the blood gas syringe.
- Obtaining a venous sample or a venous admixture
- Alterations in temperature
- Do not pull back on the plunger of the syringe while obtaining
arterial blood.
- Be sure the needle is attached securely to the syringe before
inserting the needle into the artery.
- If a sufficient amount of blood has been obtained, remove the
needle and expel the air bubbles from the syringe.
- If not, remove the needle, apply pressure to the site, wait 5 minutes,
and obtain the sample at another site with a new needle and syringe.
Arterial Blood Gases
. The date and time of the ABG sampling should be
recorded in the narrative notes.
• Also record the reason for the test, the results of the
Allen’s test, the client’s response to the blood sampling,
and any unusual observations.
• Note the route and amount of oxygen the client is
receiving and any respiratory assessment
• Record the condition of the puncture site prior to the
blood draw and after the blood draw.
• Be sure to note the follow-up check on the condition of
the site.
Any question
Thanks for Attention

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