How fitting that the SMACCdub talk, What Scares You, has recently been released, and, to some extent, discusses pediatric bleeding. Well, this paper discusses high risk peds (febrile infant <60 days) and (post LP) bleeding, and whether or not ultrasound assisted guidance helps.
SPOILER ALERT: (it probably does).
From February 2007-December 2007 (wow, talk about a knowledge translation delay), the authors attempted to enroll 46 total patients to either standard LP without ultrasound vs ultrasound assisted LP. Here’s one key point – while ultrasound guidance means direct visualization of the needle into the desired space (like for central lines or paracentesis), ultrasound assisted means that landmarks were sonographically visualized, and then they marked the skin and estimated how deep was too deep for the needle, then performed the LP (without direct visualization.-Basically they performed an ultrasound to determine a “maximum safe depth” to limit needle advancement to avoid traumatic taps, since this is a common element of LP failure in this age group.
Patients with known spinal abnormality or VP shunt were excluded, and the procedures were done by either a house officer or pediatric NP with MD oversight (so, I’m not certain how applicable this is to those of us with significant experience in this age group). Unfortunately, the study was terminated prior to reaching their goal of enrolling 23 patients into each group due to academic calendar demands of the lead author (21 vs 22 patients in either arm – meh.) Success was defined as <10k RBC and whether or not CSF was obtained. Their 5 month historical failure rate was 44%.
The groups did not differ in terms of prematurity, patient weight or length, there was a lower median age in ultrasound assisted group (38 days vs 45 days p=0.02), which may give them a bit more of an uphill battle. The results are seen below:
On first glance, these look good – less frequent traumatic taps, more frequently obtaining CSF with NNTs of 3.7 and 5.6 respectively. However, with such a small sample size, a Fragility index of 1, and having house officers and NP’s do the tap (with an unclear level of experience), I’m not certain this is broadly applicable to all providers, particularly when you add that 19 sono-assisted attempts are not enough to reach 80% success in this study. With that said, we commonly perform interventions with much lower NNTs with higher risks to the patient than a few ultrasonic waves. This is a cant hurt, will probably help intervention that we should probably be utilizing more frequently for all of our patients, not just our pediatric population.
For a great review on this topic check out sonomojo for more on ultrasound use for LPs.