COMPUTED TOMOGRAPHIC STUDY OF LUMBAR (L3-4) EPIDURAL DEPTH AND ITS RELATIONSHIP TO PHYSICAL MEASUREMENTS IN YOUNG-ADULT MEN

Background and Objectives. This study was performed to devise a method for predicting epidural depth more accurately with a variety of physi cal measurements not previously studied. Methods. Computed tomography was used to accurately measure the L3-4 epidural depth. The inclusion criteria were restricted to healthy men, 20-25 years of age, in order to rule out the influences of age and sex. Results. Significant correl ations with depth from skin to the center of the ''triangular'' poster ior epidural space (Sk-Ep) were found for waist circumference, waist c ircumference/height ratio, body mass index (BMI), weight/height ratio, weight/neck circumference ratio, and weight. The depth from the supra spinous ligament to the center of the posterior epidural space (Sl-Ep) did not correlate with any physical measurements. However, Sk-Sl, whi ch equals Sk-Ep minus Sl-Ep (ie, the depth from the skin to the supras pinous ligament) correlated with waist circumference/height ratio, wai st circumference, BMI, and weight/height ratio. Conclusion. Addition o f the physical parameters such as waist circumference/neck circumferen ce ratio or BMI results in a higher predictive value for epidural dept h than use of more traditional physical parameters such as weight/heig ht ratio and/or weight only. The value of Sl-Ep is independent of any physical parameters. Thus, the significant correlation between the phy sical measurements and the epidural depth seems to be due only to obes ity-related factors.