title: Prediction by computerised tomography of distance from skin to epidural space during thoracic epidural insertion.
abstract: In this single group observational study on 29 patients, we describe a technique that predicts the depth of the epidural space, calculated from the routine pre-operative chest computerised tomography (CT) scan using Pythagorean triangle trigonometry. We also compared the CT-derived depth of the epidural space with the actual depth of needle insertion. The CT-derived and the actual depths of the epidural space were highly correlated (r = 0.88, R2 = 0.78, p < 0.0001). The mean (95% CI) difference between CT-derived and actual depths was 0.26 (0.03-0.49) cm. Thus, the CT-derived depth tends to be greater than the actual depth by between 0.03 and 0.49 cm. There were no associations between either the CT-derived or the actual depth of the epidural space and age, weight, height or body mass index.
authors.affiliation: Department of Anaesthesia, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK. CarnieJ@heartsol.wmids.nhs.uk
authors.forename: J
authors.initials: J
authors.lastname: Carnie
authors.forename: J
authors.initials: J
authors.lastname: Boden
authors.forename: F
authors.initials: F
authors.lastname: Gao Smith
mesh_terms: D000328:Adult; D000368:Aged; D015360:Analgesia, Epidural / Q000379:methods*; D000886:Anthropometry / Q000379:methods; D004824:Epidural Space / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009339:Needles; D010149:Postoperative Pain / Q000628:therapy*; D012867:Skin; D013908:Thoracotomy; D014057:Tomography, X-Ray Computed