Written by Rick Ramirez, APRN, DNP
When ultrasound (US) is available and providers have training on US guided LP, the chance of first pass success increases versus standard landmark visualization in adult patients. US guided LPs also decrease the incidence of traumatic and multiple attempts and improve procedural time and success rates.
Why does this matter?
When sepsis guidelines recommend antibiotics be infused within an hour, the task of successfully completing an LP for those at risk for meningitis can be time consuming and daunting. Initiating empiric antibiotic therapy can create false-negative CSF results. If delaying LP completion results in a delayed diagnosis of bacterial meningitis, that is associated with increased mortality. Most EDs have access to a point-of-care-ultrasound (POCUS), and RCTs have demonstrated that using POCUS for LP guidance reduces insertion attempts, needle redirections and improves overall success rates. This is a systematic review.
To image or not to image…. there is no question!
Typical landmark palpation for LP uses the intercristal line (the imaginary line across the top of the iliac crests); however, 30% of ED patients have difficult to palpate landmarks, and landmark palpation alone has a reported 28% failure or traumatic tap rate. Using US may improve success. Interestingly, one of the referenced studies noted that 100% of patients with a BMI greater than 30 kg/m2 found the intercristal line was located ABOVE the L4-L5 space. Also, there was no supportive data in using dynamic versus static LP guidance. This position paper has a summary of 10 recommendations specifically for static LP guidance – all condensed and summarized in these few statements.
US is preferred to landmarks – use it if available and trained in it, especially in obese patients.
Use a curvilinear probe for accurate visualization and depth of the lower lumbar spine starting at the sacrum and working cephalad.
Mark the L4-L5 space longitudinally and transversely to insure first pass success.
Finally, train, train, train and practice, practice, practice.
We covered another meta-analysis on US-guided LP about a year ago. It also has links to some great videos.
Recommendations on the Use of Ultrasound Guidance for Adult Lumbar Puncture: A Position Statement of the Society of Hospital Medicine. J Hosp Med. 2019 Oct 1;14(10):591-601. doi: 10.12788/jhm.3197. Epub 2019 Jun 10.
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Reviewed by Clay Smith