Common Diagnostic

procedures in pediatrics

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

Puncture

Primary indication for emergent spinal tap

is possibility of CNS infection

The second indication for an emergent

spinal puncture is a suspected

spontaneous subarachnoid hemorrhage.

Subarachnoid Hemorrhage

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 vomiting.

Over age 3yrs: nuchal rigidity, Kerning's sign.

Petechial rash in a febrile child

Contraindications for LP

presence of infection in the tissues near the

puncture site.

Increased ICP--The presence of papilledema,

retinal hemorrhage.

A sudden drop in intraspinal pressure by rapid

release of cerebrospinal fluid (CSF) may cause fatal

herniation.

Bleeding diathesis: A platelet count is desirable

before LP.

Equipment

Spinal needle

Three-way stopcock

Manometer

3 specimen tubes

Local anesthesia

Betadine

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.

Procedure

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.

Procedure

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.

Procedure

Position the patient:

Generally performed in the lateral decubitus position.

A pillow is placed under the head to keep it in the same plane as the spine.

Lower back should be arched toward practitioner.

Procedure

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.

Procedure

Sterile gloves MUST be used.

Wash back with antiseptic solution.

Sterile towel under hips.

The skin and deeper subcutaneous tissue are infiltrated

with local anesthetic.

Warn patient of transient discomfort of anesthetic.

Procedure

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.

Procedure

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.

Procedure

If bone is encountered,

withdrawal into subcutaneous

tissue and redirect.

Attach a manometer and

record opening pressure.

Turn stopcock and collect

fluid.

Withdrawal needle and place

a dressing.

Procedure

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.

Interpretation

Appearance

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

Interpretation

Cells

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

meningitis.

Interpretation

Cells

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.

Interpretation

Cells

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 patients.

Interpretation

Glucose

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 significance

Interpretation

Low CSF Glucose Syndromes

Bacterial meningitis Syphilis

Tuberculous meningitis Chemical meningitis

Fungal meningitis Subarachnoid meningitis

Sarcoidosis Mumps meningitis

Meningeal

carcinomatosis

Herpes simplex

encephalitis

Amebic meningitis Hypoglycemia

Interpretation

Protein

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 Infections

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 Infections

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 Infections

Viral Studies

The organisms most commonly isolated in viral meningitis

are enteroviruses and mumps.

Enteroviruses: summer and fall

Mumps: winter and spring

CSF Analysis with Infections

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

Complications

Headache After Lumbar

Puncture

Most common complication

Occurs 5-30% of all spinal

taps

Usually starts up to 48 hours

after to procedure.

Usually lasts 1-2 days (occas

14 days)

Complications

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.

Complications

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 improvement.

Problem

Pain down one leg

during the procedure

Cause

The spinal needle may have

touched a dorsal nerve root

Actiona. Reposition the needle.

b. Reassure the patient

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

Backache b) Position required a)

Insertion of needle to

procedure

a) Reassure patient

b) Lie flat

c) Take analgesia

Leakage a) Leakage of cerebro- spinal

fluid.

a) No further action required

b) Report immediately if

associated with other

symptoms

Deterioration in

neurological status

Presence of space occupying

lesion in the brain not

appreciated

Need medical assistance

immediately.

Recommendations for nurses

1- prepare all equipments before starting the procedure.

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 immediately.

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

ASSESSMENT

-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

ASSESSMENT

-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

Procedure

- Prepare the heparinized syringe before going into the client’s room.

- Remember that superficial arteries are at the distal ends of

extremities.

- 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

sample.

Procedure

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 sample.

- Alterations in temperature

COMMON ERRORS

Prevention:

- 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