Chiesi Hungary Ltd, Budapest, Hungary.
Centre for Energy Research, Budapest, Hungary.
J Hosp Infect. 2021 Dec;118:7-14. doi: 10.1016/j.jhin.2021.08.025. Epub 2021 Sep 3.
There are concerns about pulmonary function tests (PFTs) being associated with aerosol generation and enhanced virus transmission. As a consequence, the number of PFTs was reduced significantly during the coronavirus disease 2019 pandemic. However, there are no robust data supporting this fear.
To perform real-life measurement of aerosol concentrations in a PFT laboratory to monitor the concentration of particles near the patient, and to model the associated potential viral load.
Two optical particle counters were used to sample the background concentration and the concentration of particles near the patient's mouth in a whole-body plethysmography box. Statistical evaluation of the measured particle concentration time series was completed. The particle exhalation rate was assessed based on the measured particle concentration data by applying the near-field/far-field theory. The number of exhaled viruses by an infected patient during the test was compared with the emission of viruses during quiet breathing and speaking.
Twenty-five patients were included in the study. Eighteen patients showed a significant increase in aerosol concentration [mean 1910 (standard deviation 593) particles/L]. Submicron particles dominated the number size distribution of the generated particles, but large particles represented a higher volume fraction in the generated particles compared with background. An average gene exhalation rate of 0.2/min was estimated from this data. This is one order of magnitude higher than the release rate for the same infected person during quiet breathing, and of the same order of magnitude as the release rate during normal speaking.
This study demonstrated that PFTs are aerosol-generating procedures. Based on these results, the moderate increase in viral load does not underpin stopping such examinations.
人们担心肺功能测试（PFT）会与气溶胶生成和病毒传播增强有关。因此，在 2019 年冠状病毒病大流行期间，PFT 的数量大幅减少。然而，目前并没有强有力的数据支持这种担忧。
在 PFT 实验室中进行实际的气溶胶浓度测量，以监测患者附近的颗粒浓度，并对相关的潜在病毒载量进行建模。
使用两个光学粒子计数器在全身体积描记箱中采样背景浓度和患者口腔附近的颗粒浓度。对测量的粒子浓度时间序列进行了统计评估。根据测量的粒子浓度数据，应用近场/远场理论评估了粒子呼出率。将感染患者在测试期间呼出的病毒数量与安静呼吸和说话时的病毒排放进行了比较。
研究纳入了 25 名患者。18 名患者的气溶胶浓度显著增加[平均值 1910（标准差 593）个/L]。亚微米颗粒主导了生成颗粒的数量大小分布，但与背景相比，生成颗粒中较大的颗粒代表了更高的体积分数。根据这些数据，估计平均基因呼出率为 0.2/min。这比同一感染患者在安静呼吸时的释放率高一个数量级，与正常说话时的释放率相同。
本研究表明，PFT 是产生气溶胶的程序。基于这些结果，病毒载量的适度增加并不能支持停止此类检查。
