X Marks the Spot (or Does It?): Ultrasonography-Assisted Site Marking for Lumbar Puncture in Children

Discussion Points

1.

Neal et al performed a randomized clinical trial comparing ultrasonography-assisted site marking with traditional lumbar puncture in infants aged 6 months or younger who presented to a single, urban, academic, pediatric emergency department (ED).
- A.
  
  What is the study’s primary outcome? Is this the outcome you would have chosen? What is the clinical significance of the chosen outcome? Consider alternative definitions for a “successful” lumbar puncture. Might a successful lumbar puncture be different for parents than providers?
- B.
  
  How would defining a traumatic lumbar puncture as cerebrospinal fluid RBC count greater than 10,000 cells/mm ³affect the sample size?
- C.
  
  The traditional lumbar puncture group had a success rate of 31%. How does the success rate in this group compare with previously reported lumbar puncture success rates? How does the success rate in the control group affect study power?
- D.
  
  The study’s clinicaltrials.gov registration is available at the following link: https://clinicaltrials.gov/ct2/show/NCT02133066?term=NCT02133066&rank=1 . Were the reported primary and secondary outcomes the same as those that were selected a priori?
2.

Ultrasonography assisted site markings were almost exclusively conducted by 1 of 2 trained sonographers. Because of the nature of the study, neither sonographer nor those performing the lumbar punctures were blinded to the study intervention.
- A.
  
  What degree of training was needed to conduct the ultrasound? Were there any differences in outcomes according to which sonographer conducted the intervention? Would the training protocol be easily translated into your setting?
- B.
  
  How was the study scanning protocol designed? Could other approaches be tried? Do ultrasounds need to be conducted by ED sonographers, or could off-site radiologists be used?
- C.
  
  How could the lack of blinding bias study outcomes? What did the investigators do to mitigate this bias?
- D.
  
  Review the Consolidated Standards of Reporting Trials (CONSORT) diagram (Figure 3 in the article by Neal et al ). What do we know about the patients excluded for convenience (sonographer not available)? Is there any evidence of selection bias? Would this affect internal or external validity?
3.

Infants were randomly assigned to ultrasonography assisted site marking versus traditional palpation technique before performance of the lumbar puncture.
- A.
  
  What type of randomization strategy was used?
- B.
  
  Were the 2 study groups similar? How did you decide this?
- C.
  
  How might differences in baseline characteristics for the 2 study arms affect results?
4.

In this study, the authors found a 27% improvement in infant lumbar puncture success (95% confidence interval 10% to 43%) when the procedure was performed with ultrasonographically assisted skin marking compared with the traditional landmark-based approach.
- A.
  
  Should sonographically marked lumbar puncture become the standard of care for infants? What other questions about this technique would you want to see answered before adopting it clinically? What barriers to implementation would you anticipate?
- B.
  
  How many infants would need ultrasonography to obtain one more successful outcome as defined by a cerebrospinal fluid RBC count less than 500 cells/mm ³on the first attempt?
- C.
  
  How might you design an implementation study using quality improvement methods to measure the effect of ultrasonography on lumbar puncture success rates? What are the relative strengths and weaknesses of conducting a clinical trial versus an implementation study?

Editor’s Note: You are reading the 57th installment of Annals of Emergency Medicine Journal Club. This Journal Club refers to the article by Neal et al published in this month’s edition of Annals . This bimonthly feature seeks to improve the critical appraisal skills of emergency physicians and other interested readers through a guided critique of actual Annals of Emergency Medicine articles. Each Journal Club will pose questions that encourage readers—be they clinicians, academics, residents, or medical students—to critically appraise the literature. During a 2- to 3-year cycle, we plan to ask questions that cover the main topics in research methodology and critical appraisal of the literature. To do this, we will select articles that use a variety of study designs and analytic techniques. These may or may not be the most clinically important articles in a specific issue, but they are articles that serve the mission of covering the clinical epidemiology curriculum. Journal Club entries are published in 2 phases. In the first phase, a list of questions about the article is published in the issue in which the article appears. Questions are rated “novice” ( ), “intermediate” ( ), and “advanced” ( ) so that individuals planning a journal club can assign the right question to the right student. The answers to this journal club will be published in the October 2017 issue. US residency directors will have immediate access to the answers through the Council of Emergency Medicine Residency Directors Share Point Web site. International residency directors can gain access to the questions by e-mailing journalclub@acep.org . Thus, if a program conducts its journal club within 5 months of the publication of the questions, no one will have access to the published answers except the residency director. The purpose of delaying the publication of the answers is to promote discussion and critical review of the literature by residents and medical students and discourage regurgitation of the published answers. It is our hope that the Journal Club will broaden Annals of Emergency Medicine ’s appeal to residents and medical students. We are interested in receiving feedback about this feature. Please e-mail journalclub@acep.org with your comments.