title: The Effects of Shoulder Rotation on the Acoustic Window for Thoracic Paramedian Epidural Approach in the Lateral Decubitus Position.
abstract: OBJECTIVE
  The aim of this study was to examine whether shoulder rotation increases the length of the posterior longitudinal ligament (PLL) in the lateral decubitus position.
  
  
  METHODS
  Thirty-four adult male volunteers were placed in the right or left lateral decubitus and flexion position on a horizontal operating table. Thoracic spinal ultrasonography was performed using the paramedian oblique sagittal plane to obtain the optimal ultrasound view for the PLL on the dependent side. The lengths of the PLL were measured at the T6/7 and T9/10 interspaces before and after ipsilateral 30-degree shoulder rotation.
  
  
  RESULTS
  In the right lateral decubitus position, the ipsilateral shoulder rotation increased the mean (SD) of the PLL from 7.4 (2.8) to 8.4 (2.6) mm (P = 0.006) at the T6/7 level and from 8.4 (2.9) to 10.6 (2.8) mm (P < 0.0001) at the T9/10 level. Similarly, in the left lateral decubitus position, the ipsilateral shoulder rotation increased the mean (SD) of the PLL from 8.0 (2.6) to 9.1 (2.6) mm (P = 0.001) at the T6/7 level and from 9.3 (2.8) to 11.8 (3.1) mm (P < 0.0001) at the T9/10 level.
  
  
  CONCLUSIONS
  Shoulder rotation significantly increased the dimension of the acoustic target window for paramedian thoracic epidural access in the lateral decubitus position at both T6/7 and T9/10 levels. Further clinical studies are needed to investigate the effect of shoulder rotation on thoracic epidural access.
authors.affiliation: From the *Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul; †Inha University College of Medicine, Incheon; and ‡Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Hyo-Jin
authors.initials: HJ
authors.lastname: Byon
authors.forename: Jang-Ho
authors.initials: JH
authors.lastname: Song
authors.forename: Kyung-Chul
authors.initials: KC
authors.lastname: Song
authors.forename: Hyunkeun
authors.initials: H
authors.lastname: Lim
authors.forename: Hyunzu
authors.initials: H
authors.lastname: Kim
mesh_terms: D000328:Adult; D015360:Analgesia, Epidural / Q000379:methods*; D059925:Anatomic Landmarks; D001696:Biomechanical Phenomena; D006801:Humans; D017846:Longitudinal Ligaments / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D009407:Nerve Block / Q000379:methods*; D056888:Patient Positioning; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012782:Shoulder / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014463:Ultrasonography