探讨呼出气一氧化氮（FeNO）在老年哮喘-慢阻肺重叠（ACO）诊断中的价值。

选取2020年1月至2022年6月浙江医院收治的稳定期老年ACO患者84例（ACO组）、稳定期单纯哮喘患者60例（哮喘组）、稳定期单纯COPD患者60例（COPD组）以及老年健康志愿者60例（健康对照组）作为研究对象。所有研究均行肺功能、呼出气测定，采用方差分析或秩和检验比较不同分组间肺功能指标和FeNO的差异，采用Spearman秩相关分析FeNO与肺功能各项指标间的相关性，并采用受试者操作特征曲线（ROC曲线）描述变量的诊断价值。

肺功能测定结果显示，ACO组和COPD组的第1秒用力呼气量占用力肺活量的百分比（FEV₁/FVC）、呼气峰值流速（PEF）和最大呼气中期流速（MMEF）均低于健康对照组和哮喘组（P<0.05）；ACO组与COPD组间上述指标的差异均无统计学意义（P>0.05）。呼出气测定结果显示，ACO组和哮喘组的FeNO水平高于健康对照组和COPD组（P<0.05），且哮喘组的FeNO水平高于ACO组（P<0.05），而COPD组与健康组间FeNO水平的差异无统计学意义（P>0.05）。Spearman秩相关性分析结果显示，在ACO组和哮喘组中，FeNO与PEF均表现出正相关性（r=0.341、0.625，P<0.05）。ROC曲线分析结果显示，当FeNO截断值为24.5 ppb时，其诊断ACO的曲线下面积（AUC）为0.771，敏感度为53.70%，特异度为87.04%；FeNO联合PEF诊断ACO的AUC为0.816，敏感度为62.96%，特异度为87.04%。

FeNO在老年ACO患者的诊断中具有较高的价值，其与PEF联合测定可进一步提高诊断效能。

To investigate the value of exhaled gas nitric oxide (FeNO) in the diagnosis of asthma-chronic obstructive pulmonary overlap (ACO) in the elderly.

Eighty-four elderly ACO patients in stable stage (ACO group) from Zhejiang Hospital during January 2020 to June 2022 were collected, and 60 patients with stable simple asthma (asthma group), 60 patients with stable simple chronic obstructive pulmonary diseases (COPD group), and 60 elderly healthy volunteers (healthy control group) were selected from the same period. Lung function and expired breath measurements were performed on all study subjects to compare the differences in lung function indexes and fractional exhaled nitric oxide (FeNO) between different subgroups by analysis of variance or rank sum test, and the correlation between FeNO and lung function indexes was analyzed using Spearman's rank correlation, and the diagnostic value of the variables was described using the receiver operator characteristic curve (ROC curve).

The results of pulmonary function measurements showed that the forced expiratory volume in one second/forced vital capacity (FEV₁/FVC), the peak expiratory flow (PEF), and the maximal mid-expiratory flow (MMEF) were lower in the ACO group and the COPD group than those in the healthy control group and the asthma group (P < 0.05); No statistically significant differences in any of the above indicators were found between the ACO and COPD groups (P > 0.05). The results of exhaled breath measurement showed that the FeNO levels in the ACO and asthma groups were higher than those in the healthy control and COPD groups (P < 0.05), and the FeNO levels in the asthma group were higher than that in the ACO group (P < 0.05), whereas the difference in the FeNO levels between the COPD group and the healthy group was not statistically significant (P > 0.05). FeNO and PEF showed positive correlation in both ACO and asthma groups (r values of 0.341 and 0.625, respectively, P < 0.05). The results of ROC curve analysis showed that the area under the curve (AUC) for diagnosing ACO was 0.771, with a sensitivity of 53.70% and a specificity of 87.04% when the FeNO cut-off value was 24.5 ppb; The AUC of FeNO combined with PEF for the diagnosis of ACO was 0.816, with a sensitivity of 62.96% and a specificity of 87.04%.

FeNO is of high efficiency in the diagnosis of ACO in the elderly, especially when it is combined with PEF.