Objective: Loss of resistance technique has been performed to identify the epidural space. However, this technique has some disadvantages including frequent lack of midline ligamentum flavum, erroneous subjective sensing, and higher failure rate. The aims of this study were to identify the optimal negative pressure representing the epidural space and to evaluate the efficacy of an epidural pressure checker to detect the epidural space. Methods: Ninety-six patients who received a trans-laminar epidural block in the spine at our institute were enrolled. Half of them received a cervical epidural block (cervical group) and the other half received a lumbar epidural block (lumbar group). Patients were randomly assigned to one of the set pressure groups (-8,-7,-6,-5,-4,-3 mbar). When the needle penetrated the ligamentum flavum, the epidural pressure checker detected negative pressure at the epidural space and alarmed with sound and light if the pressure detected was below the set pressure. Results: In the cervical group, detection rates were 62.5%, 75%, 75% at set pressure values of-8,-7,-6 mbar, respectively, and 87.5% at-5 mbar. In the lumbar group, rates were 50%, 62.5%, 62.5% at set pressure values of-8,-7,-6 mbar, respectively, and 87.5% at-5 mbar. False positives were frequent below a set pressure of-4 mbar. Conclusion: The optimal pressure value to detect the epidural space was-5 mbar. The epidural pressure checker may be a reliable, easy and useful tool to aid in the administration of a trans-laminar epidural block.

Cervical epidural injection (CEI), which is widely used for the treatment of cervical radiculopathy, sometimes has been associated with post-operative complications. Recently, EPI-DetectionTM, which detects the negative pressure of the epidural space and notifies the proceduralist by flashing a light and producing a beeping sound, was introduced. We assumed that the newly developed device could be as safe and efficient as the conventional loss of resistance (LOR) method. Therefore, we aimed to evaluate the effectiveness of the EPI-DetectionTM and compare it to that of the conventional LOR method. We randomly assigned 57 patients to the LOR and EPI-Detection groups (29 and 28 patients, respectively). Subjects were treated with interlaminar CEI (ILCEI) using one of two methods. The measured parameters, i.e., operation time and radiation dose were lower in the EPI-DetectionTM group (4.6 ± 1.2 min vs. 6.9 ± 2.1 min; and 223.2 ± 206.7 mGy·cm2 vs. 380.3 ± 340.9 mGy·cm2, respectively; all p < 0.05) than in the LOR group. There were no complications noted in either group. Both the EPI-DetectionTM and LOR methods were safe and effective in detecting the epidural space, but the former was superior to the latter in terms of operation time and radiation exposure. The EPI-DetectionTM may help perform ILCEI safely.