Obtaining cerebrospinal fluid (CSF) for the diagnosis of central nervous system (CNS) disorders such as meningitis/encephalitis. Infections that can be diagnosed are bacterial, viral, fungal and TORCH (Toxoplasmosis, Other infections[usually syphilis], Rubella, Cytomegalovirus, and Herpes simplex).
To aid in the diagnosis of intracranial hemorrhages. CSF studies are indicative but not diagnostic for intracranial hemorrhage. Can see large number of RBC's, xanthochromia, increased protein content, and hypoglycorrhachia (abnormally low CSF glucose content).
To diagnose an inborn error of metabolism. CSF amino acid analysis can be obtained to rule out nonketotic hyperglycinemia. Postmortem CSF (1–2 mL frozen specimen) is recommended when an inborn error of metabolism is suspected.
Draining CSF in communicating hydrocephalus associated with intraventricular hemorrhage. (Serial lumbar punctures for this are controversial.)
Administration of intrathecal medications or contrast material.
Monitoring efficacy of antibiotics used to treat CNS infections by examining CSF fluid.
Equipment. Lumbar puncture kit (usually contains three sterile specimen tubes; four sterile tubes are often necessary, sterile drapes, sterile gauze, 20-to 22-gauge 1-in spinal needle with stylet, 1% lidocaine), gloves, povidone-iodine solution, 1-mL syringe.
Procedure. Normal CSF values are listed in Table 32–1.
Contraindications include increased intracranial pressure (risk of CNS herniation), uncorrected bleeding abnormality, infection near puncture site, and lumbosacral abnormalities that may interfere with identification of key structures.
An assistant should restrain the infant in either a sitting or a lateral decubitus position, depending on personal preference. An intubated, critically ill infant must be treated in the lateral decubitus position. Some advocate that if CSF cannot be obtained in the lateral decubitus position, the sitting position should be used. In the lateral decubitus position, the spine should be flexed (knee-chest position). The neck should not be flexed because of an increased incidence of airway compromise; maintain airway patency. Supplemental oxygen used before the procedure or increasing oxygen if the infant is already on it can prevent hypoxemia. Monitor vital signs and pulse oximetry during the procedure.
Once the infant is in position, check for landmarks (Figure 32–1). Palpate the iliac crest and slide your finger down to the L4 vertebral body. Then use the L4-L5 interspace (preferred) as the site of the lumbar puncture. Make a nail imprint at the exact location to mark the site.
Prepare the materials (open sterile containers, pour antiseptic [povidone-iodine] solution into the plastic well located in the lumbar puncture kit).
Put gloves on and clean the lumbar area with antiseptic solution, starting at the interspace selected. Prep in a widening circle from that interspace up and over the iliac crest.
Drape the area with one towel under the infant and one towel covering everything but the selected interspace. Keep the infant's face exposed.
Palpate again to find the selected interspace. At this time, 0.5–1% lidocaine (dose in Chapter 69) can be injected subcutaneously for pain relief (optional and usually not done in neonates.). Note: Physiologic instability is not reduced with lidocaine use during ...
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