負壓隔離病房通風性能與感染風險之研究

Study on Ventilation Efficiency and Infection Risk of Negative Pressure Differential Isolation Rooms

董雲春(Yun-Chun Tung)

指導教授 ： 胡石政

國立臺北科技大學/機電學院/機電科技研究所/博士(2008年)

https://doi.org/10.6841/NTUT.2008.00197

摘要

負壓隔離病房通風系統，通常採用換氣率配合壓差控制。但國內外標準或法規對隔離病房的負壓差或換氣率，並無一致之建議或規定。以往對隔離病房通風性能研究，大多著眼在進排風口等配置的影響。由於缺乏文獻說明不同的負壓差與換氣率對通風性能的影響，因此本研究進行實驗量測，以提供對這個議題的理解。此外，當隔離病房門開啟時，壓差控制就喪失隔離效果。傳統的緩衝室設計，雖能抑止病菌漫延到緩衝室外，卻無法降低置身其中醫護人員受病菌感染的威脅。於是本研究提出氣流隔離，以計算流體力學分析其隔離效率。昔日，曾有研究以Wells-Riley方程式，分析換氣率對感染風險的影響。本研究將該方程式寫入計算流體力學軟體Fluent內，進一步探討門縫與換氣率對感染風險分佈的影響。研究結果顯示，(1)隔離病房通風性能(EI)與壓差(ΔP, Pa)及換氣率(ACH)之關係可以表示為 。(2)當隔離病房門開啟時，通過房門流速大於0.22m/s之氣流，可抑制隔離病房內污染物擴散。於緩衝室內發現之污染物平均濃度，僅為污染源原始濃度之0.0005%。(3)維持壓差(-8Pa)及換氣率(12ACH)不變情況下，在大滲入風量(穿過20mm門縫)的案例中，醫護人員對高劑量(如麻疹)、低劑量(如流感)和極低劑量(如鼻病毒)等感染源之感染風險，分別比小滲入風量(穿過1mm門縫)的案例減少12%、73%和79%。

關鍵字

隔離病房 ； 計算流體力學 ； 實驗 ； 壓差 ； 氣流 ； Wells-Riley

並列摘要

Control of pressure differential with ventilation rate has been commonly used for the ventilation system of hospital isolation rooms. Various levels of negative pressure differential and ventilation rate have been recommended, but no consensus has been reached so far as previous studies have focused on the influences of the arrangements of supply and exhaust vents on the ventilation effectiveness in an isolation room. In response to the lack of literature addressing the effects of pressure differentials and ventilation rates on the ventilation efficiency of isolation rooms, this study conducted experimental measurements to provide insights into the issue. Moreover, when the door of an isolation room is opened, the pressure differential control tends to be compromised and fails to prevent the dispersion of infectious diseases out of the isolation room. A traditional anteroom in front of the isolation room can prevent the dispersion of infectious diseases in the case of door opening but does not help reduce the risk of airborne transmission of communicable infections on healthcare workers in the anteroom. This study accordingly proposed a concept of airflow control and employed computational fluid dynamics (CFD) to analyze the effectiveness of ventilation systems with a special regard to the protection of healthcare workers. The Wells-Riley equation was used to investigate the effect of ventilation rate on infection risk and incorporated into CFD software Fluent to further analyze the influence of door gaps and ventilation rates on the spatial distribution of airborne transmission of infection risk. Results showed that (1). the relationship between the ventilation efficiency (EI) and the pressure differential (ΔP, Pa) and air change rate per hour (ACH) could be expressed as ; (2). when the door to the isolation room was opened, an airflow velocity above 0.22 m/s via the doorway was capable of preventing the spread of airborne contaminants from the isolation room, and the average room concentration of airborne contaminants in the anteroom was about 0.0005% of the one at the source generated by the patient; and (3). when the pressure differential was maintained at -8 Pa and the ventilation rate at 12 ACH, the case of the larger infiltration air rate via 20 mm door gap created the additional benefit of reducing the overall infection risk of high (like measles), low (like influenza), and very low (like rhinovirus) infectious agents by 12%, 73%, and 79% respectively as compared to the case of the smaller infiltration air rate via 1 mm door gap.

並列關鍵字

Isolation room ； Computational fluid dynamics (CFD) ； Experiment ； Pressure differential ； Airflow ； Wells-Riley

參考文獻

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