Computational fluid dynamics study on the influence of an alternate ventilation configuration on the possible flow path of infectious cough aerosols in a mock airborne infection isolation room.
Computational fluid dynamics study on the influence of an alternate ventilation configuration on the possible flow path of infectious cough aerosols in a mock airborne infection isolation room.
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计算流体动力学研究替代通风配置对模拟空气传播感染隔离室中传染性咳嗽气溶胶可能流动路径的影响。
DOI：
10.1080/23744731.2016.1222212
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发表时间：
2016
影响因子：
1.9
通讯作者：
Mead KR
中科院分区：
文献类型：
--
作者：
Thatiparti DS;Ghia U;Mead KR
当传染性流行病发生时，它们可能在卫生保健环境中持续存在，可能导致严重的卫生保健人员缺勤、发病率、死亡率和经济损失。空气传播感染隔离室的通风系统配置是保护医护人员免受感染患者生物气溶胶的作用的因素之一。虽然空气传播感染隔离室的设计通常与空气传播的传染病有关，但它也会影响其他传播途径，如受传染病集中和再循环影响的短程空气传播途径、混合传播途径和接触传播途径。本文介绍了模拟空气传播感染隔离室中通风结构对生物气溶胶扩散行为可能的流动路径的影响的计算流体力学研究。首先，模拟空气传播感染隔离室，该隔离室具有与现有医院中观察到的传统天花板安装的通风布置相对应的房间几何形状和布局、通风参数和加压。然后模拟了另一种通风配置，将线性送风扩散器保留在最初的模拟空气传播感染隔离室中，但将方形送风和排气位置互换，以使排气更靠近患者来源，并允许来自送风口的清洁空气在进入受污染患者的空气空间之前从房间未受污染的部分流动到从干净到肮脏的流动路径。模拟的交替空气传播感染隔离室通风率为每小时12次换气。两个人类呼吸模型被用来模拟来源患者和接受治疗的医护人员。在模拟中引入了患者咳嗽周期，并采用多相流模拟方法对空气中的感染扩散进行了实时跟踪。另一种构型的结果显示，患者咳嗽后，咳嗽气雾剂被排气口拉出而没有遇到医护人员，并控制了颗粒，因为从患者到天花板排气的空气颗粒流线不会打断从患者排出的咳嗽气溶胶。然而，并不是所有的气雾剂都被排出了房间。剩下的咳嗽气雾剂于0.98时进入医护人员的呼吸区，进入医护人员接触空气传播病毒的关键阶段之一，为医护人员吸入咳嗽气雾剂对健康造成不良影响提供了机会。在S的2小时内，咳嗽气雾剂重新进入患者和医护人员的周围，导致旧的污染空气袋。到这个时候，由于气溶胶不再非常接近，并且它们的运动主要受空气传播的感染隔离室气流模式的影响，聚结损失减少。在患者和医护人员远离供应器的区域，新风供应未能到达房间的这一部分，以迅速稀释咳嗽气雾剂浓度。除排气速度高、离排气格栅非常近的区域外，排气对咳嗽气溶胶的去除影响也很小。在患者咳嗽后5-20分钟内，气雾剂倾向于分解，形成直径小于1微米的较小尺寸的气雾剂。它们仍在空中飞行，并被卷进送风气流中，扩散到整个房间。悬浮的气雾剂导致S在房间内的漂浮时间超过21个咳嗽周期。由于接二连三的咳嗽周期，房间内空气传播的持续时间及其与医护人员的长期接触很可能发生。因此，评估的替代空气传播感染隔离室在患者咳嗽后第一秒内不能有效去除接触医护人员的至少38%的颗粒物。
When infectious epidemics occur, they can be perpetuated within health care settings, potentially resulting in severe health care workforce absenteeism, morbidity, mortality, and economic losses. The ventilation system configuration of an airborne infection isolation room is one factor that can play a role in protecting health care workers from infectious patient bioaerosols. Though commonly associated with airborne infectious diseases, the airborne infection isolation room design can also impact other transmission routes such as short-range airborne as well as fomite and contact transmission routes that are impacted by contagion concentration and recirculation. This article presents a computational fluid dynamics study on the influence of the ventilation configuration on the possible flow path of bioaerosol dispersal behavior in a mock airborne infection isolation room. At first, a mock airborne infection isolation room was modeled that has the room geometry and layout, ventilation parameters, and pressurization corresponding to that of a traditional ceiling-mounted ventilation arrangement observed in existing hospitals. An alternate ventilation configuration was then modeled to retain the linear supply diffuser in the original mock airborne infection isolation room but interchanging the square supply and exhaust locations to place the exhaust closer to the patient source and allow clean air from supply vents to flow in clean-to-dirty flow paths, originating in uncontaminated parts of the room prior to entering the contaminated patient’s air space. The modeled alternate airborne infection isolation room ventilation rate was 12 air changes per hour. Two human breathing models were used to simulate a source patient and a receiving health care worker. A patient cough cycle was introduced into the simulation, and the airborne infection dispersal was tracked in time using a multi-phase flow simulation approach. The results from the alternate configuration revealed that the cough aerosols were pulled by the exhaust vent without encountering the health care worker by 0.93 s after patient coughs and the particles were controlled as the aerosols’ flow path was uninterrupted by an air particle streamline from patient to the ceiling exhaust venting out cough aerosols. However, not all the aerosols were vented out of the room. The remaining cough aerosols entered the health care worker’s breathing zone by 0.98 s. This resulted in one of the critical stages in terms of the health care worker’s exposure to airborne virus and presented the opportunity for the health care worker to suffer adverse health effects from the inhalation of cough aerosols. Within 2 s, the cough aerosols reentered and recirculated within the patient and health care worker’s surroundings resulting in pockets of old contaminated air. By this time, coalescence losses decreased as the aerosol were no longer in very close proximity and their movement was primarily influenced by the airborne infection isolation room airflow patterns. In the patient and health care worker’s area away from the supply, the fresh air supply failed to reach this part of the room to quickly dilute the cough aerosol concentration. The exhaust was also found to have minimal effect upon cough aerosol removal, except for those areas with high exhaust velocities, very close to the exhaust grill. Within 5–20 s after a patient’s cough, the aerosols tended to break up to form smaller sized aerosols of less than one micron diameter. They remained airborne and entrained back into the supply air stream, spreading into the entire room. The suspended aerosols resulted in the floating time of more than 21 s in the room due to one cough cycle. The duration of airborne contagion in the room and its prolonged exposure to the health care worker is likely to happen due to successive coughing cycles. Hence, the evaluated alternate airborne infection isolation room is not effective in removing at least 38% particles exposed to health care worker within the first second of a patient’s cough.
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DOI：
10.1016/j.jhin.2006.05.022
发表时间：
2006-10
期刊：
The Journal of hospital infection
影响因子：
--
作者：
Tang JW;Li Y;Eames I;Chan PK;Ridgway GL
通讯作者：
Ridgway GL
影响因子：
4.5
作者：
Drinka, PJ;Gravenstein, S;Shult, P
通讯作者：
Shult, P
影响因子：
--
作者：
PACHUCKI, CT;PAPPAS, SAW;SCHAAFF, DM
通讯作者：
SCHAAFF, DM
影响因子：
120.7
作者：
PATRIARCA, PA;WEBER, JA;SCHONBERGER, LB
通讯作者：
SCHONBERGER, LB
DOI：
10.1089/jam.1997.10.105
发表时间：
1997-01-01
期刊：
Journal of aerosol medicine : the official journal of the International Society for Aerosols in Medicine
影响因子：
--
作者：
Papineni, R S;Rosenthal, F S
通讯作者：
Rosenthal, F S