低溫感覺測試無法避免硬脊膜外導管錯置——最小感知電流之測量為一項可以定量評估硬脊膜外阻斷的新技術

Cold Sensitivity Test Cannot Eliminate Epidural Catheter Misplacement - Minimal Perception Current Measurement as A Novel Technology to Quantitatively Evaluate an Epidural Blockade

導管錯置到肋膜腔中為置放硬脊膜外導管的少見併發症。這個病歷報告呈現的是一位因頸男部腫瘤經手術，放射治療後的患者，在進行胸腔腫瘤切除術前，接受硬脊膜外導管置放，以作為術後使用自控式止痛之用。然而雖然這個病例導管置放是在非麻醉狀態下進行，且使用了阻力消失，負壓回抽，與低溫感覺測試等方法來確認導管的位置卻仍然無法避免將硬脊膜外導管錯置到肋膜腔中。文中探討錯置的導管沒有被及早發現的原因，並提出定量評估硬脊膜外阻斷程度的新技術，希望藉以及早診斷硬脊膜外導管錯置的狀況。在美國麻醉醫學會2007年的年會中，Yamakage等學者發表一研究報告，透過測量最小感知電流藉以評估皮膚敏感度與老化的關係。查閱文獻發現，最小感知電流未曾被應用於硬脊膜外阻斷的定量評估。考量到一般使用低溫感覺測試來評估硬脊膜外阻斷的效果，只能比較不同皮節的感覺差異。然而，如報告中的病例，不同皮節的感覺差異是很有可能原本就存在的。因此當某部位低溫感覺較低，可能是阻斷成功，或者是該部位原有的感覺差異所造成。我們主張透過測量同一部位在進行硬脊膜外阻斷前與阻斷後的最小感知電流，來定量地評估阻斷的效果，進而可以及早發現導管錯置的狀況，減少低溫感覺測試的誤差未來更可望將最小感知電流測量之技術應用於其他神經阻斷與疼痛治療之範疇。

Interpleural misplacement is a rare complication of epidural catheter insertion.We report a case in which the combination of catheter placement in an awakepatient, loss of resistance technique, negative aspiration as well as cold sensitivitytest failed to identify epidural catheter misplacement. The possible reasons for thefailure to diagnose the misplacement of the epidural catheter are discussed. A noveltechnique to quantitatively evaluate an epidural blockade which may aid in earlydiagnosis of epidural catheter misplacement was introduced.While evaluating an epidural blockade by cold sensitivity test, the decrease incold sensitivity may reflect the effect of blockade or preexisting sensitivityvariation, as in the case. A more reliable method was mandatory to evaluateepidural blockade and may aid in confirmation of epidural catheter placement. Atthe 2007 annual meeting of the American Society of Anesthesiologists, Yamakageet al presented their study on skin sensitivity and aging by measuring minimalperception current (MPC) with Painvision . While there was no studies regardingthe application of MPC to quantitatively evaluate epidural neural blockade beenpublished, we suggest that by comparing the MPC measured by Painvisionbefore and after epidural blockade, the intensiveness and the coverageof se ns or yblockade could be quantitatively measured. Unexplained weak or ineffective blockwhich may resulted from a misplaced epidural catheter could be identified before afailed block does happen.