title: Depth of the thoracic epidural space in paramedian approach.
abstract: OBJECTIVE
  To define the depth of the thoracic epidural space in the paramedian axis.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Operating room of a tertiary care medical center.
  
  
  METHODS
  Nine hundred ninety-eight consecutive adults scheduled for elective major cardiothoracic/abdominal surgery and postoperative thoracic epidural pain control.
  
  
  METHODS
  The thoracic epidural pain control was accomplished via paramedian approach at indicated levels in 977 of 998 patients with uniform and well-standardized technique routinely performed in this institute.
  
  
  METHODS
  The depth of the epidural space, defined as the distance from the needle tip just penetrating the epidural layer to the overlying skin, was measured by directly checking the length markers displayed on the needle. Association between demographic variables and epidural depths at different thoracic levels was analyzed.
  
  
  RESULTS
  The mean thoracic epidural depth was (mean+/-SD) 5.11+/-0.94 cm, which was positively correlated with the body weight (regression coefficient=0.039, P<.001) and body mass index but was unrelated to sex, age, or body height. On stepwise linear multivariate regression analysis, each 10 kg of increase in body weight would result in a 0.39-cm increase in the depth. Besides, this paramedian depth was 0.34 cm longer at upper thoracic levels (T9 and upper) than that at lower levels (T10 and lower, P<.001).
  
  
  CONCLUSIONS
  Body weight, body mass index, and anatomical levels determine the paramedian thoracic epidural depth. The greater the patient's weight and the higher the puncture level, the deeper the thoracic epidural space from the body surface.
authors.affiliation: Department of Anesthesiology, Taichung Veterans General Hospital, Taichung 40766, and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.
authors.forename: Hui-Chin
authors.initials: HC
authors.lastname: Lai
authors.forename: Tsun-Jui
authors.initials: TJ
authors.lastname: Liu
authors.forename: Shih-Kuei
authors.initials: SK
authors.lastname: Peng
authors.forename: Kwong-Chiu
authors.initials: KC
authors.lastname: Lee
authors.forename: Hsiang-Ning
authors.initials: HN
authors.lastname: Luk
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D015360:Analgesia, Epidural / Q000379:methods*; D004824:Epidural Space / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010149:Postoperative Pain / Q000628:therapy*; D012189:Retrospective Studies; D013904:Thoracic Vertebrae