局部抽氣裝置對手術房麻醉廢氣移除之效能評估

A Local Scavenging System to Remove Waste Anesthetic Gases during General Anesthesia

背景：為降低手術房內麻醉廢氣對麻醉人員所造成的健康危害，本研究開發一移除麻醉廢氣之局部抽氣裝置，並對此抽氣裝置進行實驗室與手術房麻醉過程之效能評估。方法：此局部抽氣裝置主要構造為：入口漏斗（內徑20公分）、連接用軟管（內徑5公分）、高效率濾網及抽氣馬達（1馬力）。為評估其捕集效率，於病人口鼻附近釋放SF6（濃度=200ppm，流量=5 1/min）作為追縱用的模擬氣體，以抽氣式霍氏紅外光譜儀(extractive FTIR)測量局部抽氣裝置所移除之SF6濃度；而第二台FTIR之採樣管固定於麻醉護士之呼吸帶，作為同時評估手術過程中醫護人員暴露於麻醉廢氣的情形。在實驗室的效率評估，乃使用假人結合前述之SF6-FTIR測試方法，以瞭解入口漏斗位置與捕集效率之關連性。結果：在三次手術之麻醉過程，使用局部抽氣裝置時，麻醉人員暴露於N20與SEV之平均暴露濃度分別降為8.7 ppm與0.06 ppm，遠低於US-NIOSH對N20(= 25 ppm)與SEV(= 2 ppm)訂定之暴露容許濃度；而三次麻醉過程局部抽氣裝置所測得的平均捕集效率為87％，略低於實驗室所量得95％的捕集效率，此捕集效率之差異，可能因局部抽氣裝置之抽氣效能受醫護人員之醫療動作（如插管或拔管）干擾所致。結論：本研究結果顯示，當使用適當設計之局部抽氣裝置，手術房麻醉廢氣濃度可消減至US-NIOSH所訂定之暴露容許濃度以下，進而降低麻醉人員的暴露風險（特別是懷孕的麻醉人員）。

Background: A local scavenging system was constructed and tested in both the operating room and the laboratory to remove the waste anesthetic gases so as to lower the exposure risk of the anesthetic personnel. Methods: A local scavenging system was developed to suck away the waste anesthetic gases (e.g., N20 and sevoflurane) escaping from the mouth and nostrils of a patient. The local scavenging system used was composed of an inlet funnel (with a diameter of 20 cm), a flexible connecting tubing, a high efficiency particulate air (HEPA) filter and a vacuum pump. To help evaluate the performance of the local scavenging system, a tracer gas (SF6) of a fixed concentration (= 200 ppm) and flow rate (= 5 1/min) was introduced around the nostrils of the patient during anesthesia. The concentrations of the gases (SF6, N20 and SEV) drawn away by the scavenging system were then determined by an extractive Fourier transform infrared (FTIR) spectrometer and those spreading around the breathing zone of the anesthesiologist were obtained by the other FTIR. In the laboratory tests, the relationship between the scavenging efficiency and the inlet funnel position was obtained using the aforementioned SF6-FTIR techniques. Results: With the application of this local scavenging system, during three surgical operations, the average personnel exposure concentrations of N2O and sevoflurane (SEV) as measured were 8.7 and 0.06 ppm, respectively. Both measured concentrations were lower than the TWA values recommended by the US-NIOSH for N2O (= 25 ppm) and SEV (= 2 ppm). Based on the tracer gas (SF6) results, it was found that the average scavenging efficiency was equal to 87%, which was lower than the laboratory testing results of 95%. The (scavenging) efficiency difference between the laboratory and on-site tests could be due to the movement and action of the anesthesiologist during anesthesia. To optimize the performance of the local scavenging device, the inlet (funnel) should be placed close to the breathing region (e.g., noses and mouth) of the patient in the front direction. Conclusions: The application of the local scavenging system was found to greatly reduce the concentrations of the waste anesthetic gases (e.g., N20 and SEV) to the levels lower than those recommended by the US-NIOSH. With this scavenging device, the exposure health risk of the anesthesiologists could be greatly reduced.