Lumbar epidural block is now a popular technique for anesthesia and post operative analgesia. It may be helpful for prevention of complication during this procedure to know the depth from the skin to the lumbar epidural space before the procedure. This study was undertaken to evaluate the depth from the skin to the lumbar epidural space and to determine any potential relationship between a patient's data (age, weight, and height) and the measured depth in Korean children.

We investigated the electronic records of 662 Korean children who were received urologic surgeries with epidural catheterization for postoperative analgesia. The patients' gender, age, weight, height and epidural depth were recorded and analyzed with multiple linear regression test using SPSS 13.0 (SPSS Co., Ilinois, USA).

The patient's age and weight were significantly correlated to the skin-epidural space depth in Korean children. Body weight was more significant variable than age on the epidural depth. The empirical formula derived from the results was as follow; epidural depth (mm) = 9 + 0.5 × body weight (kg) - 0.2 × age (months).

We suggest that the depth of skin-lumbar epidural space can be estimated with the empirical formula based on body weight and age.