呼出气一氧化氮对哮喘的诊断作用及与过敏原sIgE的关系

目的探讨呼出气一氧化氮(FeNO)对哮喘的诊断作用及与过敏原特异性IgE抗体(sIgE)的关系。方法选取2017年8月至2019年8月收治的98例疑似哮喘患儿进行观察,收集所有患儿的临床特征指标,检测肺功能及FeNO浓度,分析FeNO对哮喘的诊断作用及其与过敏原sIgE的关系。结果哮喘组的FeNO水平高于非哮喘组(P<0.05)。血清过敏原sIgE阳性患儿的Fe NO水平高于阴性患儿(P<0.05)。经Pearson相关性分析得出,FeNO水平与血清过敏原sIgE、血清总IgE和血清过敏原种类呈显著正相关(r=0.703、0.624、0.719,P<0.05)。结论FeNO在哮喘中具有一定的诊断价值,与过敏原sIgE存在显著的相关性,可为临床诊断与治疗哮喘提供有利参考依据。     

The value of small airway function parameters and fractional exhaled nitric oxide for predicting positive methacholine challenge test in asthmatics of different ages with FEV1 ≥ 80% predicted

BackgroundSmall airway function parameters (SAFPs) combined with fractional exhaled nitric oxide (FeNO) can predict a positive methacholine challenge test (MCT) for asthma diagnosis. However, their predictive utility in patients with forced expiratory volume in one second (FEV₁) ≥80% predicted within different age ranges remains unclear. This study aimed to assess the utility of SAFPs, alone or combined with FeNO, to predict a positive MCT in patients in two age groups (<55 and ≥55 years) with asthma‐suggestive symptoms and FEV₁ ≥80% predicted.MethodsWe enrolled 846 Chinese patients with suspected asthma and standard spirometry, FeNO, and MCT findings. Using the area under the curves (AUCs), the utility of SAFPs, alone or combined with FeNO, for predicting a positive MCT was analyzed in a discovery (n = 534) and validation cohort (n = 312) in both age groups with FEV₁ ≥80% predicted.ResultsIn the discovery cohort, the optimal cut‐off values for predicting a positive MCT in patients aged <55 years (74.2% and 74.9% for forced expiratory flow (FEF)_50% and FEF_25%–75%, respectively) were higher than those in patients aged ≥55 years (65.0% and 62.9% for FEF_50%, FEF_25%–75%, respectively). However, the optimal FeNO value in patients aged <55 years (43 ppb) was lower than that in patients aged ≥55 years (48 ppb). FeNO combined with SAFPs (FEF_50%, FEF_25%–75%) significantly increased the AUCs in both groups (≥55 years [0.851 for FEF_50% and 0.844 for FEF_25%–75%]; <55 years [0.865 for FEF_50% and 0.883 for FEF_25%–75%]) compared with a single parameter (p < 0.05). These findings were confirmed in the validation cohort. Compared with patients ≥55 years, those aged <55 years had higher and lower optimal cut‐off values for SAFPs and FeNO, respectively. The AUCs of FeNO combined with SAFPs for predicting a positive MCT for asthma diagnosis were significantly higher than those of the individual parameters (p < 0.05) in both age groups.ConclusionsThere were age‐group differences in the utility of SAFPs combined with FeNO for predicting a positive MCT. Patients with an asthma‐suggestive history and a normal FEV₁ should be stratified by age when using SAFPs combined with FeNO to predict a positive MCT.     

肺泡气一氧化氮在初始治疗前低FeNO哮喘患者治疗中的价值

目的 探讨初始治疗前低呼出气一氧化氮(FeNO)哮喘患者中,肺泡气一氧化氮(CaNO)水平升高能否作为吸入糖皮质激素/长效β2受体激动剂(ICS+LABA)治疗获益的预测因子.方法 收集该院呼吸与危重症医学科就诊的具有哮喘临床特征、舒张试验阳性且FeNO≤50 ppb的患者60例作为研究对象,依据CaNO水平是否升高分...     

Repeatability of exhaled nitric oxide measurements in patients with COPD

The assessment of the presence of eosinophilic airway inflammation may help in predicting the steroid response in subjects with respiratory symptoms. Unlike patients with asthma, only a subset of patients with chronic obstructive pulmonary disease (COPD) benefits from steroid treatment. Fractional exhaled nitric oxide (FENO) is a useful surrogate marker for eosinophilic airway inflammation, but data on the repeatability of FENO measurements in COPD needed for the assessment of significant change are insufficient. The aim of this study was to assess the short-term repeatability of FENO measurement in subjects with moderate to very severe chronic airway obstruction compared to that in healthy subjects. We studied 20 patients with stable COPD and 20 healthy subjects, and determined FENO (flow rate 50 ml s(-1) ) three times: at baseline, 10 min and 24 h after baseline. Spirometry was performed on the first study day after the FENO measurements. The median FENO concentration in patients with COPD was 15·6 ppb, and in healthy subjects, 15·2 ppb. The coefficient of variation (CoV) for 24-h measurements was 12·4% in COPD patients, and 15·9% in healthy subjects. Among COPD patients with global initiative for chronic obstructive lung disease stage 2 disease, the CoV was 13·7%, and among those with stage 3-4 disease, 10·5%. The findings indicate that the short-term repeatability of FENO measurement in patients with moderate to very severe COPD is equally good as in healthy subjects. A change in FENO exceeding 24% is likely to reflect a minimum measurable change in COPD.     

呼出气一氧化氮检测在哮喘儿童孟鲁司特治疗中的应用价值

目的探讨呼出气一氧化氮(FeNO)检测在哮喘儿童孟鲁司特治疗中的应用价值。 方法选择2013年5月至2014年5月于复旦大学附属上海市第五人民医院儿科门诊就诊的5～14岁哮喘儿童,共40例。给予入组患儿孟鲁司特常规治疗12周,随访6次并检测入组患儿FeNO水平,测定晨起呼气峰流速(PEF),并计算PEF占预计值的百分比(PEF%pred),记录儿童哮喘控制评分(C-ACT)。根据孟鲁司特治疗前及治疗12周时的哮喘控制水平分级变化,将入组患儿分为显效组和无效组,采用SPSS 17.0对不同分组的临床资料进行分析。最后有31例患儿完成为期12周的研究,其中显效组21例,无效组10例。 结果两组患儿在哮喘病史时间[(2.36±2.03)年,(3.60±1.51)年]、病情分级(部分控制/未控制)(16/5,1/9)、起始C-ACT评分[(20.71±0.85)分,(19.30±1.57)分]、起始FeNO水平[(9.93±7.69)ppb,(32.52±22.70)ppb]方面比较,均差异具有统计学意义(t＝1.72,χ²＝11.98,t＝3.29,t＝4.15;均P<0.05)。显效组患儿起始FeNO水平为(9.93±7.69)ppb,孟鲁司特治疗12周,前后测量结果比较,差异无统计学意义(F＝0.51,P>0.05);无效组患儿治疗前起始FeNO水平为(32.52±22.70)ppb,孟鲁司特治疗12周,前后测量结果之间差异无统计学意义(F＝0.56,P>0.05)。两组患儿孟鲁司特治疗后,PEF%pred、C-ACT评分均提高,6次测量结果之间均差异具有统计学意义(F＝4.63,6.06,50.67,6.09;均P<0.05)。两组患儿孟鲁司特治疗12周期间,除显效组患儿治疗2周时FeNO水平与PEF%pred呈正相关(r＝0.44,P<0.05)外,FeNO水平与PEF%pred、FeNO水平、C-ACT评分无相关性(P>0.05)。 结论FeNO与PEF%pred、C-ACT评分相比暂不具有明显的疗效监测价值,哮喘患儿的病史、病情分级、起始C-ACT评分、起始FeNO水平等因素可能会影响孟鲁司特的疗效。     

呼出气一氧化氮对呼吸机相关性肺炎的早期诊断意义

目的:探讨呼出气一氧化氮(FeNO)对呼吸机相关性肺炎(VAP)的早期诊断意义。方法:选择入住首都医科大学附属复兴医院重症医学科(ICU)需要进行有创机械通气的患者。收集患者人口学资料,第1、3、5、7天FeNO、白细胞计数(WBC)、降钙素原(PCT)及预后指标,前瞻性观察FeNO是否对VAP具有早期诊断意义。按照入ICU的主要原因分为肺内炎症组、肺外炎症组及非炎症组;将机械通气时间≥3 d的患者,根据14 d内是否发生VAP分为VAP组和非VAP组。结果:肺内炎症组患者FeNO浓度明显高于肺外炎症组及非炎症组(P0.05)。与非VAP组患者相比,VAP组患者第3天和第5天的FeNO明显升高,其对VAP的发生与否有良好的临床预测价值(第3天:AUC 0.87,P0.001,分界点6.5 ppb,敏感性76.9%,特异性81.4%;第5天:AUC 0.75,P=0.001,分界点为5.5 ppb,敏感性73.1%,特异性67.4%)。与非VAP组患者相比,VAP组患者28 d内非机械通气时间缩短(P0.05)、ICU住院时间延长(P0.05)。结论:肺炎患者FeNO明显升高,升高的FeNO对VAP有很好的临床预测价值,在临床中可以作为VAP的一项生物标志物。     

呼出气一氧化氮联合相关因素对咳嗽变异性哮喘的诊断价值评价

目的 :评价呼出气一氧化氮(Fe NO)检测单独或联合咳嗽变异性哮喘(cough variant asthma,CVA)相关因素对诊断CVA的有效性和准确性。方法:连续纳入2010年8月至2011年10月本院呼吸科门诊因慢性咳嗽行支气管激发试验检查的患者297例,记录病史并测定呼出气Fe NO水平,以支气管激发试验阳性作为CVA诊断的金标准,绘制ROC曲线,探讨诊断CVA的Fe NO临界点。建立Logisitic回归模型,通过分析筛选与CVA相关的因素,根据ROC曲线评价Fe NO联合其他相关因素对CVA的诊断价值。结果:145例患者支气管激发试验阳性并排除其他疾病被诊断为CVA(哮喘组),152例支气管激发试验阴性患者诊断为非哮喘的慢性咳嗽(非哮喘组)。1哮喘组患者Fe NO水平明显高于非哮喘组[(45.33±38.86)ppb比(26.28±23.86)ppb,P     

呼出气一氧化氮与胸腺基质淋巴细胞生成素在咳嗽变异性哮喘中的临床意义

目的研究咳嗽变异性哮喘(CVA)与呼出气一氧化氮(FeNO)、胸腺基质淋巴细胞生成素(TSLP)的相关性,推测其在CVA病理生理中的可能机制。方法收集2016年7月至2018年12月就诊于包头市中心医院呼吸科门诊及住院的病例:CVA患者67例(CVA组),嗜酸性粒细胞支气管炎(EB)患者8例(EB组)。选择同期健康体检者14名(健康对照组)。分别进行FeNO及血清TSLP的含量测定。采用单因素方差分析比较3组间上述资料的差异,不同组间的两两比较采用LSD-t检验法。采用Pearson相关分析分析CVA组FeNO与TSLP指标间的相关性。采用多元线性回归分析分析影响CVA组FeNO水平的因素,采用逐步法筛选变量(α入=0.10,α出=0.15)纳入合适的变量。结果FeNO水平在CVA组、EB组和健康对照组之间差异具有统计学意义(F=7.344,P=0.001);CVA患者FeNO水平显著高于健康对照组[(60.88±42.85)×10^-9 mol/L vs(17.64±4.91)×10^-9 mol/L],差异具有统计学意义(t=4.35,P<0.001);EB组FeNO水平高于健康对照组[(66.50±42.35)×10^-9 mol/L vs(17.64±4.91)×10^-9 mol/L)],差异具有统计学意义(t=2.71,P=0.008);CVA组患者和EB组患者比较,差异无统计学意义(P>0.05)。CVA组TSLP水平明显高于EB组[(421.60±111.65)ng/L vs(338.81±119.98)ng/L];EB组TSLP水平明显高于健康对照组[(338.81±119.98)ng/L vs(233.34±51.39)ng/L];CVA组血清TSLP水平显著高于健康对照组,差异均具有统计学意义(t=4.11、7.36、5.88,P均<0.001)。血清总IgE浓度在CVA组、EB组和健康对照组中比较,差异均无统计学意义(P>0.05)。CVA组FeNo与血清TSPL值呈正相关(r=0.258,P=0.035)。TSPL值、身高对FeNO水平均有影响。结论(1)FeNO和血清TSLP水平均与气道炎症相关。(2)单一的FeNO测定可能不能作为CVA与EB的鉴别标准。(3)血清TSLP水平参与了气道炎症的发生和发展,有助于慢性咳嗽CVA和EB的诊断和鉴别诊断。     

呼出气一氧化氮测定对吸入糖皮质激素治疗慢性阻塞性肺疾病疗效的预测价值

目的探讨呼出气一氧化氮（fraction of exhaled nitric oxide,FENO）测定预测慢性阻塞性肺疾病（chronicobstructive pulmonary disease,COPD）患者吸入糖皮质激素（inhaled corticosteroid,ICS）治疗疗效的价值。方法 31例戒烟的重度COPD患者（第1s用力呼气容积（forced expiratory volume in one second,FEV1）占预计值百分比〈50%）,试验前进行无ICS的洗脱期后,给予沙美特罗替卡松吸入剂500μg,2次/d,连用4周,测定试验前FENO和试验后肺功能变化。结果基线FENO与使用ICS后FEV1变化无相关性;对ICS有反应者（FEV1增加≥200mL）较对ICS无反应者FENO基线值明显增高（P=0.028）,利用FENO诊断有反应者与无反应者的AUC为0.767。结论对已戒烟的重度COPD患者,FENO是一个较好的预测ICS治疗疗效的指标。     

92例咳嗽变异性哮喘患者的呼出气一氧化氮浓度与气流阻塞的相关研究

目的:观察咳嗽变异性哮喘(cough variant asthma,CVA)患者的呼出气一氧化氮浓度(F E NO)变化及其与气流阻塞间的相关性。方法:2012年7月至2013年6月经支气管激发试验确诊的92例CVA成人患者,分别行常规肺功能、脉冲振荡肺功能和F E NO检测。结果:92例CVA患者中44例的F E NO>50 ppb,34例的F E NO为25~50 ppb,仅14例F E NO     

雾化吸入氯胺酮对哮喘大鼠肺组织一氧化氮及一氧化氮合酶的影响

目的通过建立大鼠支气管哮喘模型,观察不同浓度氯胺酮对哮喘大鼠肺组织iNOS活性及NO含量的影响。方法SD大鼠随机分成对照组(N组)、哮喘模型组(A组)、不同浓度氯胺酮预处理组(分别为K1组、K2组)和地塞米松组(D组),每组8只。A组大鼠用卵白蛋白辅以百日咳杆菌菌苗和氢氧化铝为佐剂注射致敏,2周后雾化吸入卵蛋白激发哮喘;氯胺酮处理组大鼠用同样方法致敏,但在激发前分别给予雾化吸入氯胺酮25 g/L(K1组)和50 g/L(K2组);D组在激发前给予雾化吸入0.01%地塞米松;N组用生理盐水替代卵蛋白进行注射和吸入。每组分别测定其肺组织NO2-/NO3-水平、肺组织诱导型NOS(iNOS)和原生型NOS(cNOS)活性水平,并用免疫组织化学法观察iNOS在大鼠哮喘模型肺组织中的分布。结果A组肺组织中NO2-/NO3-和iNOS水平升高,iNOS和肺组织NO2-/NO3-水平呈高度正相关;K1、K2组肺组织中NO2-/NO3-和iNOS水平低于A组(P<0.05);D组肺组织中NO2-/NO3-和iNOS水平亦低于A组(P<0.05)。结论25 g/L或50 g/L的氯胺酮雾化吸入可抑制哮喘大鼠肺组织iNOS活性,降低NO含量,减轻大鼠肺部炎症。     

呼出气一氧化氮测定在支气管哮喘诊断和管理中的价值

慢性气道炎症是支气管哮喘的本质。临床上急需能客观准确地反映气道炎症的炎性标志物来指导哮喘的诊断和管理,呼出气一氧化氮(FeNO)测定是一种符合临床需要的快速检测方法,现就FeNO在哮喘诊断、气道炎症监测、哮喘严重程度评级及预测哮喘发作等方面的研究进展做一综述。     

Performance of fractional exhaled nitric oxide in predicting response to inhaled corticosteroids in chronic cough: a meta-analysis

Background. Chronic cough is a disabling condition with a high proportion of diagnostic and therapeutic failures. Fractional exhaled nitric oxide (FeNO) has been considered a useful biomarker for predicting inhaled corticosteroids (ICS) response. We evaluated the relationship between FeNO and ICS response in chronic cough by performing a systematic review with meta-analysis.Methods. PubMed, Web of Science, Scopus and EMBASE databases were systematically searched. Differences were expressed as Odds Ratio (OR) with 95% confidence intervals (95%CI). Pooled sensitivity, specificity, positive (PLR) and negative likelihood ratio (NLR), and area under the hierarchical summary receiver operating characteristic curve (HSROC_AUC) were estimated.Results. Nine articles on 740 chronic-cough patients showed that the response rate to ICS was 87.4% (95%CI: 83.8–91.0) in 317 patients with a high FeNO and 46.3% (95%CI: 41.6–51.0) in 423 controls, with an attributable proportion of 47.0% and a diagnostic OR of 9.1 (95%CI: 3.7–22.4, p < .001). The pooled estimate of diagnostic indexes resulted in a sensitivity of 68.5% (95%CI: 46.7–84.4) and specificity of 81.9% (95%CI: 63.0–92.3), with a HSROC_AUC of 0.82 (95%CI: 0.64–0.90). In a realistic scenario with a pre-test probability set at 30%, based on a pooled PLR of 3.79 (95%CI: 1.24–7.47) and NLR of 0.38 (95%CI: 0.22–0.66), the post-test probability was 62% with a high FeNO and 14% if the test was negative. Subgroup analyses confirmed a better performance for the recommended FeNO cut-off greater than 25 ppb. Meta-regression and sensitivity analyses showed no impact of major demographic and clinic variables on results.Conclusions. A high FeNO before starting ICS therapy may help identify chronic-cough patients responding to treatment, with a better performance ofhigher cut-off values. Further studies are needed to evaluate the real usefulness of this biomarker to guide cough therapy and optimise strategies in different healthcare settings (community, hospital, rehabilitation).

Key messages

• Chronic cough is a disabling condition with a high proportion of diagnostic and therapeutic failures.
• Fractional exhaled nitric oxide (FeNO) may be a useful biomarker for identifying chronic cough patients who respond to steroid treatment.
• A FeNO cut-off lower than 25 ppb should be considered irrelevant for this clinical application.

     

Humming-induced release of nasal nitric oxide for assessment of sinus obstruction in allergic rhinitis: pilot study

BACKGROUND: Humming greatly increases nasal nitric oxide (NO) in healthy people by causing a rapid washout of NO from the sinuses. This increase is abolished in patients with complete sinus ostial obstruction. OBJECTIVE: Allergic rhinitis is a risk factor for development of sinusitis and we wanted to study whether nasal NO measurement during humming could be used to detect sinus abnormalities in this disorder. METHODS: Fifty-nine consecutive subjects with mild to moderate allergic rhinitis were studied. Their present nasal symptoms were recorded. Then NO levels were measured by chemiluminescence during quiet single-breath nasal exhalations and humming exhalations at a fixed exhalation flow of 0.2 L s(-1). Based on the NO results the patients were divided into two groups: those with a great increase in nasal NO during humming (humming responders, n = 46) and those without a significant increase (humming nonresponders, n = 13). In 11 of the nonresponders and in 22 of the responders the passage to the osteomeatal complex area was assessed and scored by nasal endoscopy. This was carried out by an oto-rhino-laryngologist unaware of the NO results. RESULTS: Among the nonresponders nine of 11 patients (80%) had endoscopic signs of bilateral sinus obstruction, compared with one of the 22 (< 5%) humming responders. Baseline nasal symptom score and NO levels during quiet exhalation were not significantly different between the groups CONCLUSION: Absence of a nasal NO peak during humming is associated with endoscopic findings suggestive of sinus ostial obstruction in subjects with allergic rhinitis. Measurement of nasal NO during humming may be a simple method to detect sinus abnormalities in these patients.     

Exhaled nitric oxide and its long‐term variation in healthy non‐smoking subjects

Exhaled nitric oxide (NOexp) is an indicator of inflammation in the airways. Reference values obtained from healthy adults or information on long‐term variation of NOexp are not yet available. The aims of this pilot study were to collect values of NOexp from a selected group of healthy adults and to assess their long‐term variation. We studied 26 healthy subjects (age 21–48, 16 male, 10 female) with normal findings in flow‐volume spirometry, pulmonary diffusing capacity, relative amount of blood eosinophils, chest X‐ray and ECG at rest. NOexp was determined according to the European Respiratory Society guidelines during slow expiration against an airflow resistance. The measurements were repeated after 7 (n=13) and 23 days (n=17). The mean value of NOexp (n=26) was 6·9 ng g^–1 (95% confidence interval, 6·0–7·9 ng g^–1). The upper limit of intra‐individual variation (+2 SD) was 11·9 ng g^–1 and the lower limit (–2 SD) 1·9 ng g^–1, respectively. The mean (SD) value of NO production (NO output) was 39·1 pmol s^–1 (20 pmol s^–1). We found no correlation between NOexp and age (r=–0·06, P=0·78) and no association of NOexp with the gender (male vs. female, P=0·40). The intraindividual coefficient of variation (CoV) was 15·8% of NOexp and 20·7% of NO output within the interval of 7 days. CoV was 16·8% of NOexp and 18% of NO output within the interval 23 days. The results suggest that NOexp values over 12 ng g^–1 are abnormally high in healthy subjects. According to the results the change of NOexp by 30–35% or more within the interval of 1–3 weeks would be abnormal.     

清肺汤对ALVARDS患者呼出气冷凝液及血清中NO的影响

目的：研究急性肺损伤（ALI）／急性呼吸窘迫综合征（ARDS）患者使用清肺汤治疗后呼出气冷凝液（EBC）和血清中一氧化氮（NO）改变的临床意义。方法：ICu行机械通气的Au／ARDs患者54例,随机分为常规治疗组（给予机械通气、液体管理、抗炎、综合营养支持等）和清肺汤治疗组（在常规治疗基础上联用中药清肺汤）。ALI／ARDS患者在第1天及第5天采用改进的德国JAEGER公司Ecoscreen呼出气冷凝液收集器收集EBC标本。54例患者均同步抽取静脉血5ml,在室温下离心留取血清。以ELISA法测定EBC和血清中的NO浓度。同时进行APACHEⅡ评分,记录氧合指数及机械通气时间。结果：①清肺汤治疗组第5天,EBC和血清中NOE（26．71±9．32）μmol／L,（31．28±8．73）μmol／L]均低于常规治疗组[（34．27±9．96）／μmol／L,（39．34±9．15）tlmol／L],均P〈0．05。②清肺汤治疗组治疗前后氧合指数差值（94．74±42．19）mmHg高于常规治疗组（68．41±35．21）mmHg,P〈0．05;③清肺汤治疗组机械通气时间（225．06±74．79）h少于常规治疗组（296．42±96．25）h,P〈0．05;④清肺汤治疗组APACHEⅡ评分（9．75±4．52）低于常规治疗组（13．02±5．31）,P〈0．05。结论：ALI／ARDs患者联用中药清肺汤有助于控制炎症反应,减轻肺损伤,可提高临床疗效。     

Validation study of nasal nitric oxide measurements using a hand-held electrochemical analyser

Background Exhaled nitric oxide (NO) measurement is a simple and non‐invasive method for monitoring airway inflammation. Similarly, nasal NO has been proposed as a surrogate marker in inflammatory diseases of the upper airways, e.g. allergic rhinitis. A new portable analyser using an electrochemical sensor has been developed for measurements of exhaled NO, and its reproducibility and comparison with other analysers has been tested recently in healthy subjects and in patients with lower airways disease. The application of this hand‐held analyser in nasal NO analysis was tested and compared to the gold standard represented by a chemiluminescence analyser. Materials and methods Thirty subjects including 15 patients with allergic rhinitis (AR) and 15 healthy subjects (HS) were studied. The intraindividual variability, calculated as the difference in nasal NO levels between two measurements from a single nasally exhaled breath manoeuvre, and the comparison between the electrochemical analyser (NIOX MINO, Aerocrine) and a chemiluminescence analyser (NOA, Sievers) were performed. Results In AR patients mean nasal NO was 59·0 ± 16·3 p.p.b. with the MINO and 58·3 ± 15·6 p.p.b. with the NOA. In HS nasal NO was 49·1 ± 10·8 p.p.b. with the MINO and 49·8 ± 8·2 p.p.b. with the NOA. The Bland‐Altman analysis showed bias values of 0·005 ± 3·6 with the 95% limits of agreement from –6·97 to 6·98 p.p.b. Conclusion Measurements of nasal NO levels with a hand‐held electrochemical analyser are reproducible and the results are comparable to a stationary chemiluminescence analyser.