School of Health and Care Professions, University of Portsmouth, Portsmouth, UK.
Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK.
J Hosp Infect. 2021 Apr;110:194-200. doi: 10.1016/j.jhin.2021.01.026. Epub 2021 Feb 4.
Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets.
To compare the droplet spread in non-laminar and laminar air flow operating theatres.
A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance.
The smallest droplet detected was ∼120 μm and the largest ∼24,000 μm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 μm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively.
Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.
降低 COVID-19 传播依赖于控制飞沫和气溶胶的传播。荧光染色显示微小飞沫。
比较非层流和层流手术室中飞沫的扩散。
将“咳嗽发生器”固定在手术车 45°处。将荧光染色的“分泌物”投射到一系列校准的目标上。在紫外光下拍摄这些目标，并使用“源检测”软件测量飞沫飞溅的大小和距离。
检测到的最小飞沫约为 120μm，最大飞沫约为 24000μm。在非层流手术室中平均检测到 25862 个斑点，而在层流手术室中为 11430 个（减少 56%）。层流气流主要影响较小的飞沫（<1000μm）。飞沫覆盖的表面积为：非层流空气中 50cm 处为 6%，2m 处为 1%，3m 处为 0.5%；层流空气中分别为 3%、0.5%和 0.2%。
使用荧光染色和图像分析可以准确绘制临床环境中的飞沫扩散图。层流气流对较小的飞沫有影响，但在我们的“气溶胶产生咳嗽模型”中对较大的飞沫影响有限。我们的结果表明，层流手术室需要与非层流手术室类似的术后清洁，医护人员应考虑为中高危患者提供全面的个人防护设备。
