使用有薄膜隔離生理食鹽水及空氣之注射針筒在找尋硬脊膜外腔時可避免把空氣注入硬脊膜外腔內

A 'Membrane in Syringe' Technique that Allows Identification of the Epidural Space with Saline while Avoids Injection of Air into the Epidural Space

背景：我們設計了一種改良式硬脊膜外腔穿刺注射針筒，我們把普通硬脊膜外腔穿刺注射針筒內加裝一個薄膜使空針腔一分為二(membrane in syringe)，前腔內可以抽生理食鹽水，後腔內可以抽空氣，空氣腔可使該注射針筒具有能擠壓空氣之彈性，生理食鹽水腔則讓在刺入硬脊膜外腔時，空氣不會被注射入硬脊膜外腔或脊髓內。方法：實驗中我們選擇20位即將接受下肢或泌尿科手術之成年人病患，在使用上述裝有薄膜的改良式注射針筒來施行硬脊膜外腔麻醉來測試此方法之效果。在施行硬脊膜外腔穿刺前，先將改良式注射針筒的前腔抽滿3 ml生理食鹽水，再於後腔內抽滿3 ml的空氣。在病患的腰背部消毒完成後，在局部麻醉下把硬脊膜外腔麻醉針刺入黃韌帶位置。隨後，再把此注射針筒接上，在一邊將針推進硬脊膜外腔時，一邊把注射針筒後腔的空氣擠壓和感覺它的彈性，同時以目測法注意注射針筒裡的薄膜是否從鼓漲轉變成皺疊狀。若失去擠壓彈性或發生薄膜皺疊則表示已到達硬脊膜外腔內。此時便將硬脊膜外導管放入腔內，並在注射局部麻醉藥10至20分鐘後測量病患的麻醉程度。結果：在這初步試驗的結果顯示18位病例在四分鐘內就可以完成硬脊膜外腔穿刺術。在使用改良式注射針筒在針達到硬脊膜外腔時僅有1 ml以下的生理鹽水被同時注入硬脊膜外腔腔內。所有病例都有達到適當的局部麻醉成效。有三個病例在硬脊膜外腔穿刺時注射針筒並沒有明顯的壓力變化(loss of resistance)而是靠目測到薄膜皺疊就成功地確定硬脊膜外腔的位置。結論：在使用改良式注射針筒來施行硬脊膜外腔麻醉時，當針頭在到達硬脊膜外腔內時，前腔的生理食鹽水便會注入腔內，並同時把硬脊膜推開，此時薄膜便會皺疊，所以施行者不但可以感覺到壓力變化，同時也會看到薄膜皺疊現象，使更明確地知道針頭已經進入硬脊膜外腔內，達成既可避免空氣注入也可預防不小心穿刺硬脊膜(inadvertent dural puncture)的目的。

Background: The 'MEMBRANE IN SYRINGE' technique is, in principle, a modification of the loss of resistance technique for identifying the epidural space in epidural anaesthesia. A plastic membrane is placed halfway inside a syringe dividing the syringe into two compartments. The saline compartment encompasses the nozzle of the syringe (the distal compartment). The plunger is installed in the opposite half of the hallow cylinder. Air is trapped in the space between the membrane and the rubber plunger (air compartment). Methods: There were altogether 20 epidural procedures to put to the test for this technique. The time spent in the undertaking of the procedure, the amount of normal saline injected, whether there was a feel of loss of resistance with wrinkling of the membrane in the syringe, inadvertent puncture of the dura, the level of epidural block and the insertion depth of epidural needle were recorded. Results: The procedure took less than 4 minutes to complete in most of the cases. There was no inadvertent dural puncture. The average amount of normal saline injected was less than 1 ml. In 3 cases, despite the absence of the feel of loss of resistance the epidural space was still successfully identified by visible wrinkling of the membrane in the syringe. All catheters were inserted smoothly through the epidural needle and appropriate level of anesthesia was achieved in all the cases. Conclusions: The advantage of this technique is twofold. Firstly when the syringe is filled with both normal saline and air, it can prevent injection of the air into the epidural space during identification while at the same time it does not molest the feel of compressibility. Secondly, with the membrane separating the normal saline and air, correct placement of the needle tip can also be ascertained with loss of resistance while, as will be seen, the plastic membrane will wrinkle when saline is released into the epidural space.