Lumbar puncture

23.18 Lumbar puncture



Ronald A. Dieckmann



Background


Lumbar puncture (LP) is a time-honoured method for obtaining cerebrospinal fluid (CSF) for diagnostic evaluation of suspected central nervous system (CNS) abnormalities. LP is an essential procedure in children with suspected meningitis, and represents the only simple method of obtaining fluid for rapid diagnosis and appropriate pathogen analysis for specific treatment. While LP is most commonly performed to diagnose meningitis, it is also a useful procedure to help identify encephalitis, CNS haemorrhage, malignancy, and other rare metabolic and degenerative conditions of childhood. Occasionally, LP is a therapeutic procedure in treatment of such conditions as pseudotumour cerebri, or for administration of intrathecal antibiotics or chemotherapeutic agents.


LP is a relatively simple procedure in infants and children but has a known complication rate, with both minor and major sequelae. Appropriate patient selection, preparation and patient positioning, and aseptic technique will avoid most complications. Do not perform LP immediately on haemodynamically unstable patients, who first require meticulous management of airway, breathing and circulation, or on patients with clinical signs of focal CNS processes or significantly elevated intracranial pressure. In such patients, obtain blood cultures and administer antibiotics first, then perform LP after stabilisation and brain imaging, when indicated.



Indications



• Clinical symptoms and signs of meningitis or encephalitis in neonate, infant or child.

• Evaluation of sepsis in infant <3 months of age.

• Seizure with fever in child <12 months of age.

• Intrathecal drug administration.


Contraindications



• Haemodynamic instability.

• Active seizure activity.

• Focal neurological signs.

• Significant intracranial pressure elevation (hypertension, bradycardia, and apnoea).

In children with possible significant intracranial pressure elevation from oedema or space-occupying brain lesions, brain herniation after LP is an important consideration. Obtain a computerised axial tomography (CT) brain scan before the LP.



Equipment


Pre-packaged LP trays are available in most hospitals.


18-, 20- or 22-gauge styleted spinal needles:
3.5-cm (1.5-inch) for neonates, infants, young children

6-cm (2.5-inch) for older children and adolescents

9-cm (3.5-inch) for large patients.

Povidone-iodine solution.

1% lidocaine.

25-gauge needle.

20-gauge needle.

3–5-mL syringe.

Four capped sterile specimen tubes.

Manometer (for children aged 2 years).

Stopcock.


Preparation and positioning



In most patients, establish secure vascular access, obtain blood cultures ×2 and appropriate blood tests, administer oxygen and begin cardiac monitoring and pulse oximetry.

Secure the airway if necessary.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Lumbar puncture

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