2019 Volume 57 Issue 6 Pages 224-229
Manikin-type epidural insertion simulators for epidural anesthesia training have been evaluated by asking anesthesiologists’feeling compared with their personal experiences. In order to evaluate the epidural insertion simulators from the engineering point of view, the author inserted an endoscope into the epidural space for visualization of the ligamentum flavum model (LF) and the needle tip, and measured the reaction force as needle insertion resistance and the pressure inside the syringe for the loss of resistance technique (LOR) . According to the LOR, after the epidural needle was inserted into the epidural insertion simulator, the inner needle was withdrawn and a pressure sensor and a syringe were attached to the needle. Both the needle and a load cell were moved in the epidural insertion simulator at a speed of 0.8mm/s. From the endoscopic images, the author obtained the timing for both needle puncture of the LF and catheter insertion as entrance of the whole needle tip into the epidural space. Two needles were compared;a needle with tip angle of 25 degrees was designated needle A, and one of 38 degrees was designated needle B. Experimental results of seven insertions for both needles A and B were as follows. (1)Tenting of the LF was the largest when the needle tip punctured the LF. (2)The pressure inside the LOR syringe started to decrease at the location of 1.41±0.65mm in needle A and 1.74±1.01mm in needle B prior to the largest tenting of the LF. (3)Insertion length and force required from puncturing of the LF to insertion of the whole needle tip into the epidural space were 3.19±0.46m and 2.36±0.35N, respectively, for needle A, and 2.64±0.29m and 2.34±0.34N for needle B. The difference in insertion length was statistically significant (p＜0.01) due to the longer bevel of needle A. (4)Insertion of the dull needle B into the epidural space required 9.38±0.83N, which was greater than that of needle A (8.49±0.87N) (p＜0.05) . Epidural insertion simulator with an endoscope for visualization of the epidural space is useful for understanding the relation between tenting of the LF and pressure inside the LOR syringe. The LF of the current epidural insertion simulator should be improved for practicing catheter insertion.
