Abstract
Several approaches of locating the epidural space have been proposed. However, loss of Resistance method (LOR) remains the most common method for epidural anesthesia. Different optical signals were received from the ligamentum flavum and the epidural space allows operator to pinpoint position of the needle and determine whether the needle tip has entered the epidural space. Optical signals throughout the penetration process was recorded and position of needle tip was confirmed with a C-arm fluoroscopy. 60 lumbar punctures were performed in 20 vivo porcine models, and success rate of locating the epidural space with the optical auxiliary is calculated statistically. The data are expressed in mean ± SD. During all the lumber puncture processes, the strength of optical signals received decreased significantly while the needle tip penetrates the ligamentum flavum and entered the epidural space. The strength of optical signal received when needle tip was in the ligamentum flavum was 1.38 ± 0.57. The signal strength at epidural space was 0.46 ± 0.35. Strength of signal decreased by 67% when entered epidural space, and there is no significant differences in decrease of strength from data obtained from thevertebrae (lumbar segments)L2-L3, L3-L4, and L4-L5. Finally, we calculated with assistance of the proposed optical auxiliary, the success rate for guiding the needle tip to the epidural space using was as high as 87%. It is evidently believed that the optical auxiliary equipped is visualized to assist operators inserting needle accurately and efficiently into epidural space during epidural anesthesia operation.
Highlights
Hanging drop technique uses “decrease in pressure” concept to identify the epidural space, it is more likely to lead to dural puncture as compared to loss of Resistance method (LOR); it is rarely used clinically[13,14]
The optical auxiliary consists of the epidural space location needle (Fig. 2A) embedded with optical fibers combined with the epidural locator apparatus
When median epidural puncture was performed, we found that the reflected signal decreased significantly as the needle tip entered the epidural spaces from the ligamentum flavum (P < 0.001)
Summary
Hanging drop technique uses “decrease in pressure” concept to identify the epidural space, it is more likely to lead to dural puncture as compared to LOR; it is rarely used clinically[13,14]. Ultrasonography and fluoroscopy methods are another two approaches to assist operators locating needle tip during epidural puncture[15]. Ultrasonography demonstrates capability of improving accuracy and safety significantly for needle positioning, but is unable to differentiate the tissues from the epidural space due to its poor resolutions. It cannot be operated independently as it requires one person to operate an ultrasound probe and another person do execute epidural puncture[17]. A signal processing device was developed to convert the received optical signals to digital data and display them on screens, turning out the new design is capable of providing feedback to assist operators performing epidural block by accurately locating the epidural space for needle placement
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