The Width of the Epidural Space Measured during Spinal Anesthesia

Lee, Sang Chul; Kim, Seok Kon

Abstract

The width of human epidural space was measured in 85 patients during spinal anesthesia. With the patient in the lateral position, the epidural space was located using a midline loss of resistance method through a 22 gauge spinal needle at either L3-4 or L4-5. After negative pressure was demonstrated, the needle was advanced without the introduction of air or fluid clear flow of CSF was established. The following parameters were recorded; age, sex, weight, height, weight/height ratio(ponderal index: PI), distance from the skin to the establishment of negative pressure(skin to epidural space: SE), distance from skin to clear flow of CSF(skin to subarachnoid space: SS), and distance from initiation of negative pressure to clear flow of CSF (epidural width: EW). The results were as follows; 1) At L3-4 epidural space, the mean values of the SE, SS and EW were 4.75+/-0.19cm, 5.36+/-0.79 cm and 6.12+/-3.49 mm, respectively. 2) At L4-5 epidural space, the mean values of the SE, SS and EW were 4.36+/-0.58cm, 5.00+/-0.74 cm and 6.33+/-3.92 mm, respectively. 3) The SE and SS measurements were increased significantly according to the increase of weight and PI. But EW showed no significant correlation with any measurement. We might say that we could predict SE and SS when we perform epidural anesthesia but have no method to predict the epidural width, thereby we have to pay special attention not to advance the needle deeply just after we enter the epidural space.