[The distance from the skin to the epidural space in general population]

Epidural block is a common regional anesthetic technique in surgical procedures. The depth of the epidural space beneath the skin surface varies at different levels of the spinal column in the same patient. It also varies from patient to patient at the same vertebral level. We studied the distance from the skin to the different lumbar epidural space in general population to determine whether there is any systematic relationship between patient age, height, weight and the distance from the skin to the epidural space. Data were gathered from 159 patients (excluded all obstetric cases) having epidural anesthesia for surgical procedures. All blocks were performed using a midline approach with lateral and knee-chest position. They divided into 3 group according to different lumbar area: (1) Group A: L1-2 interspace, 33 cases; (2) Group B:L3-4 interspace, 54 cases; (3) Group C: L4-5 interspace, 72 cases. Data were analyzed by single linear regression and one-way ANOVA with p less than 0.05 considered statistically significant. The results revealed that: In Group A, there were relationship between patient age [r2 = 0.137, p less than 0.05], weight [r2 = 0.35, P less than 0.0003] and weight-height ratio.[r2 = 0.36, P less than 0.0002] with the distance from the skin to the epidural space (depth); but no relationship between body height.(ABSTRACT TRUNCATED AT 250 WORDS)