Abstract
Impairment of diffusion capacity is the most common abnormality in discharged patients with COVID-19. Both decreased alveolar volume andKCO有助于扩散能力受损的发病机制。莫re follow-up work is needed.计画ps://bit.ly/2YL2eaK
From the authors:
We are grateful for the opportunity to respond to the letter by S. Nusair, whom we thank for his interest and thoughtful remarks about our study on the abnormal pulmonary function in coronavirus disease 2019 (COVID-19) patients [1]。
Diffusing capacity of the lung for carbon monoxide (DLCO) reflects the capacity of carbon monoxide transfer from the environment to the pulmonary capillary blood, which is the most clinically useful routine methodology to evaluate the function of the lung to exchange gas.KCO是来自肺泡气体的一氧化碳吸收的速率常数,这主要受肺泡毛细管的厚度和面积的影响,毛细血管中血红素中的血液中的血液的体积,以及肺泡毛细血管中血红蛋白的浓度和性质。DLCO主要由KCO和the alveolar volume (VA). Mathematically,KCOcan be calculated asDLCO/VAunder body temperature, ambient pressure, saturated with water vapour conditions [2]。
We agree with S. Nusair that it should be noted thatDLCO/VA不是一个简单的比例,实际上肺体积和一氧化碳摄取之间的关系是线性的,并且肯定小于1:1 [3]。Recent studies have tended to useKCOinstead ofDLCO/VA, as it may be inferred from the use of the termDLCO/VAthatDLCOcan be normalised forVA。The 2017 European Respiratory Society/American Thoracic Society standards for single-breath carbon monoxide uptake in the lung recommends that the term ofKCO是首选的DLCO/VA[2]。但是,在实践中,来自不同制造商的许多肺功能测试报告仍然存在DLCO/VA和notKCO。Besides, in order for an easier and direct comparison with some previous studies on pulmonary function in patients with severe acute respiratory syndrome (SARS) [4,5],DLCO/VA保留在我们的报告中。了解对诠释的重要性KCO和DLCO/VA, but the term ofKCO建议将来更多流行使用。
DecreasedKCOoccurs in alveolar-capillary damage, microvascular pathology or anaemia. Causes of lowVA包括减少肺泡膨胀,肺泡损伤或损失,或者通过气流阻塞的激发气体陈述。什么时候KCOturns normal, in the presence of a lowDLCOit is associated with lowVA。Because only the functional alveolar units had been sampled, a biased picture toward more preserved areas of the lungs is thereby provided [3]。Crucially, the sameDLCOmay occur with various combinations ofKCO和VA, each suggesting different pathologies. It is difficult to interpret which is the predominant role because both decreased alveolar volume andKCO有助于扩散能力受损的发病机制。DLCO对肺的气体交换进行全面评估,而肺泡 - 毛细管膜漫射能力为一氧化碳(DMCO) only dependents on molecular diffusion of the membranes. However,DMCOcan be calculated using different equations but is not yet standardised, and as such is not a commonly used gas diffusing parameter [6]。
在我们的研究中,51例Covid-19患者受损DLCO, including 29 patients who showed both impairedDLCO和KCO。两种患者的数量都受损DLCO和KCO(29/51) was 24% larger than the number of patients with impairedKCOalone (22/51). Moreover, the percentage of patients with decreased total lung capacity was less than the percentage of patients with decreasedKCO。Furthermore, vascular injury and thrombosis have been demonstrated to be important contributing factors in the pathogenesis of COVID-19. SARS coronavirus 2 infects the endothelial cellsvia血管紧张素转化酶2.对内皮细胞的免疫细胞募集促进了几种器官中内皮炎的诱导,这有助于系统性受损的微旋转功能[7]。临床过程中报告了急性肺栓塞[8]。Post mortem研究报告了多个器官中的血管损伤和血栓[7,9]。ACKERMANNet al.[10.] compared the lung pathology of COVID-19 with H1N1. The result showed that patient with COVID-19 presented distinctive vascular features, consisting of severe endothelial injury associated with the disruption of intercellular junctions, cell swelling and a loss of contact with the basal membrane. From the above, it is probable that the effect of membrane lesion plays an important role on the impaired diffusion capacity in patients with COVID-19.
Our study showed that, similar toDLCO,DLCO/VA(代表一氧化碳的转移系数)也表现出与疾病严重程度的关联:随着患者进入更严重的病症,平均值DLCO/VA与预测值相比较低。由于标准偏差值表明个体差异对肺功能产生影响,因此我们还提供了分布DLCO/VAof predicted in patients with different severities. 42% of the subjects with severe pneumonia had aDLCO/VAof less than 80% of predicted, compared to only 27% in the patients with pneumonia and 13% in patients with mild illness, respectively.
In previous follow-up studies of SARS, impairedDLCO被定义为何时DLCO无论如何,是预测值的<80%KCO或肺泡体积。在恢复SARS患者0.5至2年的后续研究中,受损DLCOwas the most common abnormality, accounting for 15.5% to 43.6% [11.–13.]。The meanDLCOranged from 77.7% to 93.8% pred in the studies above, with the longest follow up of 2 years. Our study showed a meanDLCO放电时的78.2%,但随访数据尚不提供。目前尚不清楚Covid-19幸存者的扩散能力受损的变化,以及如何在胸部计算机断层扫描(CT)上反映变化的变化。在一项研究中,在入院后6个月出现存活的SARS患者,43个(75.4%)的患者表现出放射性异常,包括62.8%的异常DLCO[11.]。Thus, the lung function impairment findings are consistent with the CT images of SARS survivors showing persistent ground glass opacity, reticular opacities and traction bronchiectasis suggesting the fibrosis [14.]。同样,在被排放的Covid-19,Wanget al.[15.] reported that 94% (66/70) of patients who were discharged from hospital at the end of the study still had mild to substantial residual lung abnormalities on their last CT scans.
Our study was a pilot study which first described the impaired pulmonary function in patients with COVID-19 at time of discharge. Impairment of diffusion capacity is the most common abnormality followed by restrictive ventilatory defects. However, more follow-up work is needed to assess the longitudinal variation of these deficits.
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Footnotes
Conflict of interest: R. Chen has nothing to disclose.
Conflict of interest: Y. Gao has nothing to disclose.
Conflict of interest: M. Chen has nothing to disclose.
利益冲突:W. Jian没有什么可披露的。
Conflict of interest: C. Lei has nothing to disclose.
Conflict of interest: J. Zheng has nothing to disclose.
Conflict of interest: S. Li has nothing to disclose.
- Received2020年6月6日。
- AcceptedJune 11, 2020.
- 版权所有©ers 2020
This version is distributed under the terms of the Creative Commons Attribution Non-Commercial Licence 4.0.