Lumbar Puncture

imagesUsed to obtain cerebrospinal fluid (CSF) and to measure the opening pressure of the subarachnoid space to aid in the evaluation and management of patients with acute headache or other symptoms of the following conditions:


   imagesMeningitis


   imagesSubarachnoid hemorrhage (SAH)


   imagesCarcinomatous meningitis


   imagesPseudotumor cerebri (occasionally for spontaneous intracranial hypotension)


   imagesOccasionally for Guillain–Barré syndrome, multiple sclerosis, inflammatory demyelinating polyneuropathy


   imagesOccasionally in cases of encephalitis


CONTRAINDICATIONS



imagesPatients who need a lumbar puncture (LP) and have any of the following should first have a brain imaging study, indicating that it is safe to perform an LP:


   imagesAltered mental status


   imagesPapilledema


   imagesNew focal neurologic examination abnormalities


   imagesElevated intracranial pressure (ICP)


   imagesAge 60 years or older (relative)


   imagesImmunocompromised


   imagesSeizure within 1 week before presentation


      imagesException, pseudotumor cerebri (where by definition, the ICP is elevated)


imagesSuspicion of spinal cord mass, or epidural hematoma/abscess


imagesSkin or soft-tissue infection overlying lumbar spine


imagesAnatomic abnormalities: For example, patients with lumbar hardware from prior spinal surgery


imagesCoagulopathic patients


RISKS/CONSENT ISSUES



imagesPost-LP headache occurs in approximately 15% to 20% of patients. Using an atraumatic or noncutting spinal needle decreases the incidence of this, and multiple therapies exist to treat this specific type of headache.


imagesThe procedure can cause local pain. Local anesthesia will be given.


imagesNeedle puncture can cause local bleeding, which is usually minimal


imagesPotential for introducing infection exists; however, this is extremely rare. Sterile technique will be utilized.


imagesTheoretical risk of damage to neural tissue exists. Such occurrences are also very rare, most often temporary, and affect spinal nerve roots, not the cord itself.


LANDMARKS



The transverse axis connecting iliac crests passes through L4 vertebral body, allowing for identification of the L4-5 and L3-4 interspaces (FIGURE 45.1)



images


FIGURE 45.1 Anatomical landmarks.


TECHNIQUE



imagesPatient Preparation


   imagesExplain the procedure to the patient and obtain patient consent


   imagesPosition the patient in either lateral decubitus or sitting position (the sitting position may be easier to use but precludes accurate ICP measurement)


imagesLateral Decubitus Position


   imagesHave the patient lie on one side, with knees to chest and head/shoulders curled toward knees as much as possible. Placing a pillow under the head helps reduce twisting of the shoulders.


   imagesEnsure that the lumbar spine lies parallel to the edge of the bed. (In an infant/child, or a poorly cooperative adult, it will be necessary to have an assistant hold the patient securely in the optimal position.) The top shoulder and hip should be directly above their bottom counterparts.


   imagesA cooperative patient can be asked to curve his/her lower back, out like an “angry cat,” to optimally open the spinous processes


imagesSitting Position


   imagesHave the patient sit on the side of the bed with the bed positioned below patient’s midthigh and with the feet of the patient touching floor, if possible


   imagesAsk the patient to curve the torso forward over a bedside table positioned in front of him/her; table height should be level with patient’s upper abdomen. A pillow may be placed on the table for patient’s comfort.


   imagesAfter positioning, but before prepping, mark the target for needle insertion with firm pressure from the Luer-lock (hub) end of a needle sheath (or some other blunt device such as a pen) firmly against the skin (which will leave a mark for several minutes and provides a visual target)


   imagesPrepare a wide area with povidone–iodine or chlorhexidine gluconate solution


      imagesEnsure the sterile field includes L4-5 and L3-4 interspaces. (Should first attempt at L4- 5 be unsuccessful, the L3-4 interspace will be readily accessible.)


      imagesUse sterile drapes to frame workspace


   imagesReassess landmarks. It is crucial that the midline be defined.


      imagesSometimes, in overweight patients, feeling the spinous processes in the thoracic spine (where they are easier to palpate) and marching down will help the clinician ensure that they are in the midline


      imagesUltrasonography has been shown to reduce the failure rate, number of attempts, and traumatic punctures and can be used as an adjunct



images


FIGURE 45.2 Needle insertion point.

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Aug 9, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Lumbar Puncture

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