title: Ultrasound imaging facilitates spinal anesthesia in adults with difficult surface anatomic landmarks.
abstract: BACKGROUND
  Poor surface anatomic landmarks are highly predictive of technical difficulty in neuraxial blockade. The authors examined the use of ultrasound imaging to reduce this difficulty.
  
  
  METHODS
  The authors recruited 120 orthopedic patients with one of the following: body mass index more than 35 kg/m² and poorly palpable spinous processes; moderate to severe lumbar scoliosis; or previous lumbar spine surgery. Patients were randomized to receive spinal anesthetic by the conventional surface landmark-guided technique (group LM) or by an ultrasound-guided technique (group US). Patients in group US had a preprocedural ultrasound scan to locate and mark a suitable needle insertion point. The primary outcome was the rate of successful dural puncture on the first needle insertion attempt. Normally distributed data were summarized as mean ± SD and nonnormally distributed data were summarized as median [interquartile range].
  
  
  RESULTS
  The first-attempt success rate was twice as high in group US than in group LM (65% vs. 32%; P < 0.001). There was a twofold difference between groups in the number of needle insertion attempts (group US, 1 [1-2] vs. group LM, 2 [1-4]; P < 0.001) and number of needle passes (group US, 6 [1-10] vs. group LM, 13 [5-21]; P = 0.003). More time was required to establish landmarks in group US (6.7 ± 3.1; group LM, 0.6 ± 0.5 min; P < 0.001), but this was partially offset by a shorter spinal anesthesia performance time (group US, 5.0 ± 4.9 vs. group LM, 7.3 ± 7.6 min; P = 0.038). Similar results were seen in subgroup analyses of patients with body mass index more than 35 kg/m and patients with poorly palpable landmarks.
  
  
  CONCLUSIONS
  Preprocedural ultrasound imaging facilitates the performance of spinal anesthesia in the nonobstetric patient population with difficult anatomic landmarks.
authors.affiliation: Department of Anesthesia, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada. gasgenie@gmail.com
authors.forename: Ki Jinn
authors.initials: KJ
authors.lastname: Chin
authors.forename: Anahi
authors.initials: A
authors.lastname: Perlas
authors.forename: Vincent
authors.initials: V
authors.lastname: Chan
authors.forename: Danielle
authors.initials: D
authors.lastname: Brown-Shreves
authors.forename: Arkadiy
authors.initials: A
authors.lastname: Koshkin
authors.forename: Vandana
authors.initials: V
authors.lastname: Vaishnav
mesh_terms: D000368:Aged; D000775:Anesthesia, Spinal; D015992:Body Mass Index; D004388:Dura Mater / Q000502:physiology; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009339:Needles; D019637:Orthopedic Procedures; D010147:Pain Measurement; D010173:Palpation; D011446:Prospective Studies; D013116:Spinal Cord / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D016896:Treatment Outcome; D014463:Ultrasonography