目的 硬脊膜外麻醉通常應用於下肢手術、下腹部手術或術後疼痛控制，但過程中可能帶來心律變化與低血壓之風險，這種血行動力學的變化，在病理生理學上乃歸因於交感神經的阻斷，導致血管擴張並可能發生休克。本研究的目的在探討如何幫助麻醉醫師，了解硬脊膜外麻醉前後自主神經的變化，以改善麻醉的品質，並避免併發症的產生。方法 選擇10位ASA Class Ⅰ成年患者，行泌尿道結石或骨科下肢手術，在接受硬脊膜外麻醉15分鐘後，利用麻醉中使用的心電圖監視器，結合電腦平台擷取與分析第二導程ECG訊號，檢測在硬脊膜外麻醉下心率變化的量化情形。結果 十位病患麻醉後阻斷界於T3-T10之間。收縮壓在麻醉後下降10% (P<0.01)，而其心率變異間期平均值降低10%，LF功率頻譜能量上升160%。結論 本研究顯示T3以下LF的功率頻譜能量與麻醉前比較，顯示有增加的趨勢，可作為在硬脊膜外麻醉下交感神經活性的量化指標。因此應特別注意此交感神經活性上升對潛在性心血管疾病患者可能的不良影響，包括併發症和死亡率的增加。
Purpose. Epidural anesthesia is usually administered before lower extremity surgery, lower abdominal surgery, or for postoperative pain relief. However, it can lead to hypotension and occasional bradycardia, which are attributed to the sympathetic blockade. Hence, it is important to understand the change in the autonomic nervous system during the peri-operative period in order to improve the quality of anesthesia and patient outcome. Methods. We enrolled 10 patients, ASA class I, who were to undergo elective urologic or lower-limb orthopedic surgeries. Epidural anesthesia was administered. A noninvasive data acquisition system obtained the ECG signals. Peri-operative blood pressure was recorded and heart rate variability (HRV) was analyzed off-line. Results. The levels of blockade were between T3 and T10. After epidural anesthesia, the systolic blood pressure decreased by 10% (p<0.01). The change in HRV was statistically significant. Low frequency (LF) power spectral density increased by 160%. Conclusion. LF power spectral density can be used as a marker of sympathetic activity of the heart below the T3 level. Physicians should be aware of the possible adverse effects due to sympathetic blockade in patients with cardiovascular disease.
