title: The use of ultrasound for lumbar spinous process identification: A pilot study.
abstract: BACKGROUND
  Clinical identification of lumbar spinous processes is inaccurate in most patients. The purpose of this study was to determine the number of patients required to train anesthesiologists in the use of ultrasound imaging to accurately identify the lumbar spinous processes.
  
  
  METHODS
  In this pilot study, two anesthesiologists studied patients scheduled for a diagnostic computed tomography (CT) scan, including the lumbar spine. Before the CT scan, the anesthesiologist completed a systematic ultrasound scan of the lumbar spine and placed a radio-opaque marker at a designated level. The actual level was determined by a radiologist after reviewing the CT scans. The primary outcome was the number of procedures each anesthesiologist needed (by cumulative sum analysis) to be able to identify the designated spinous process 90% of the time. Secondary outcomes included the overall success rate, the magnitude of the failures (number of segments from the designated spinous process), and the incidence of spinal anomalies and their effect on reliability.
  
  
  RESULTS
  We studied 74 patients. One anesthesiologist required 36 patients to meet reliability criteria, whereas the other required 22 patients. The overall accuracy rate was 68%. There were only two patients where the marker was placed more than one segment from the designated spinous process. The incidence of lumbar spine anomalies was 6.8% (n = 5), and 80% (n = 4) of these were associated with inaccurate marker placement.
  
  
  CONCLUSIONS
  It is possible to use ultrasound scanning to accurately identify the lumbar spinous processes in unselected patients. This result suggests that, with appropriate training, this tool can be used to enhance the accuracy of needle placement during neuraxial techniques.
authors.affiliation: Department of Anesthesia, Women's College Hospital, University of Toronto, 76 Grenville Street, Toronto, ON, M5S 1B2, Canada. Stephen.Halpern@sunnybrook.ca
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Halpern
authors.forename: Arnab
authors.initials: A
authors.lastname: Banerjee
authors.forename: Renato
authors.initials: R
authors.lastname: Stocche
authors.forename: Phyllis
authors.initials: P
authors.lastname: Glanc
mesh_terms: D000328:Adult; D000368:Aged; D000776:Anesthesiology / Q000379:methods; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D018084:Ultrasonography, Interventional / Q000379:methods*