Recommendations on the Use of Ultrasound Guidance for Adult Lumbar Puncture: A Position Statement of the Society of Hospital Medicine
1) When ultrasound equipment is available, along with providers who are appropriately trained to use it, we recommend that ultrasound guidance should be used for site selection of lumbar puncture to reduce the number of needle insertion attempts and needle redirections and increase the overall procedure success rates, especially in patients who are obese or have difficult-to-palpate landmarks.
2) We recommend that ultrasound should be used to more accurately identify the lumbar spine level than physical examination in both obese and nonobese patients.
3) We suggest using ultrasound for selecting and marking a needle insertion site just before performing lumbar puncture in either a lateral decubitus or sitting position. The patient should remain in the same position after marking the needle insertion site.
4) We recommend that a low-frequency transducer, preferably a curvilinear array transducer, should be used to evaluate the lumbar spine and mark a needle insertion site. A high-frequency linear array transducer may be used in nonobese patients.
5) We recommend that ultrasound should be used to map the lumbar spine, starting at the level of the sacrum and sliding the transducer cephalad, sequentially identifying the lumbar spine interspaces.
6) We recommend that ultrasound should be used in a transverse plane to mark the midline of the lumbar spine and in a longitudinal plane to mark the interspinous spaces. The intersection of these two lines marks the needle insertion site.
7) We recommend that ultrasound should be used during a preprocedural evaluation to measure the distance from the skin surface to the ligamentum flavum from a longitudinal paramedian view to estimate the needle insertion depth and ensure that a spinal needle of adequate length is used.
8) We recommend that novices should undergo simulation-based training, where available, before attempting ultrasound-guided lumbar puncture on actual patients.
9) We recommend that training in ultrasound-guided lumbar puncture should be adapted based on prior ultrasound experience, as learning curves will vary.
10) We recommend that novice providers should be supervised when performing ultrasound-guided lumbar puncture before performing the procedure independently on patients.
© 2019 Society of Hospital Medicine
KNOWLEDGE GAPS
The process of producing these guidelines revealed areas of uncertainty and important gaps in the literature regarding the use of ultrasound guidance for LP.
First, it is unclear whether the use of ultrasound guidance for LP reduces postprocedural back pain and whether it improves patient satisfaction. Several studies have evaluated postprocedural back pain28,30,32,33,52 and patient satisfaction28,29,33,51 with the use of ultrasound guidance, but these studies have found inconsistent results. Some of these results were probably due to insufficient statistical power or confounding variables. Furthermore, benefits have been demonstrated in certain subgroups, such as overweight patients or those with anatomical abnormalities, as was found in two studies.52,87 Use of ultrasound guidance for spinal anesthesia has been shown to reduce postprocedural headache28 and improve patient satisfaction51, although similar benefit has not been demonstrated in patients undergoing LP.
Second, the effect of using ultrasound guidance on the frequency of traumatic LPs is an area of uncertainty. A “traumatic tap” is defined as an inadvertent puncture of an epidural vein during passage of the spinal needle through the dura. It remains difficult to discern in these studies whether red blood cells detected in the CSF resulted from puncture of an epidural vein or from needle trauma of the skin and soft tissues. Despite this uncertainty, at least seven randomized controlled studies have assessed the effect of ultrasound guidance on traumatic LPs. The meta-analysis by Shaikh et al. included five randomized controlled studies that assessed the effect of ultrasound guidance on the reporting of traumatic taps. The study found a reduced risk of traumatic taps (risk ratio 0.27 [95% CI 0.11-0.67]), an absolute risk reduction of 5.9% (95% CI 2.3%-9.5%), and a number needed to treat of 17 (95% CI 11-44) to prevent one traumatic tap.16 Similarly, the meta-analysis by Gottlieb et al. showed a lower risk of traumatic taps among adults undergoing LP with ultrasound guidance in five randomized controlled studies with an odds ratio of 0.28 (95% CI 0.14-0.59). The meta-analysis by Gottlieb et al. included two adult studies that were not included by Shaikh et al.
Third, several important questions about the technique of ultrasound-guided LP remain unanswered. In addition to the static technique, a dynamic technique with real-time needle tracking has been described to perform ultrasound-guided LP, epidural catheterization, and spinal anesthesia. A pilot study by Grau et al. found that ultrasound used either statically or dynamically had fewer insertion attempts and needle redirections than use of landmarks alone.29 Three other pilot studies showed successful spinal anesthesia in almost all patients88-90 and one large study demonstrated successful spinal anesthesia with real-time ultrasound guidance in 97 of 100 patients with a median of three needle passes.91 Furthermore, a few industry-sponsored studies with small numbers of patients have described the use of novel needle tracking systems that facilitate needle visualization during real-time ultrasound-guided LP.92,93 However, to our knowledge, no comparative studies of static versus dynamic guidance using novel needle tracking systems in human subjects have been published, and any potential role for these novel needle tracking systems has not yet been defined.
Finally, the effects of using ultrasound guidance on clinical decision-making, timeliness, and cost-effectiveness of LP have not yet been explored but could have important clinical practice implications.
