Characterization of airway nitric oxide in allergic rhinitis: the effect of intranasal administration of L-NAME

Nasal nitric oxide measurement in allergic rhinitis and non-allergic rhinitis: a meta-analysis

The goal of this meta-analysis was to study nasal nitric oxide (nNO) measurements in allergic rhinitis (AR) and non-allergic rhinitis (non-AR). The protocol was registered with PROSPERO (no: CRD4202124828). Electronic databases from PubMed, Google Scholar, Scopus, Web of Science, and Cochrane were all thoroughly searched and studies were chosen based on the qualifying requirements. The quality of the studies was evaluated by Joanna Briggs Institute evaluation tools, and publication bias using funnel plots. The meta-analysis included 18 studies, whereas the systematic review included 20 studies, totaling 3097 participants (1581 AR, 458 non-AR, and 1058 healthy/control). Patients with AR had significantly greater nNO levels than the control group, although this did not change significantly before or after treatment. AR patients had significantly greater nNO levels than non-AR patients, but there was no significant difference between non-AR patients and healthy controls. Nineteen of the studies were of high quality and the remaining one was of moderate quality. nNO measurement has a promising role in the management of AR and non-AR patients, but more investigations are needed to document clinical benefits.

Nasal nitric oxide testing for allergic rhinitis patients: Systematic review and meta-analysis

BACKGROUND

Nasal nitric oxide (nNO) levels in allergic rhinitis (AR), healthy people or nonallergic rhinitis (NAR) have shown contradicting results in previous studies. By meta-analysis, we reviewed studies that measured nNO in AR patients to assess nNO's ability to discriminate AR from healthy people or NAR.

METHODS

We systematically searched PubMed, Cochrane, Embase, Ovid, Web of Science, Wanfang Data, CNKI until December 15, 2020. Differences were expressed as standardized mean differences (SMD) with 95% confidence interval (CI), by random-effects method.

RESULTS

A total of 10 original studies with 561 AR patients, 327 healthy controls, 123 NAR patients were included in the narrative synthesis and 9 studies in the meta-analysis. nNO in AR was significantly increased compared with healthy controls (SMD: 0.989; 95% CI: 0.402, 1.576; p = .001) or NAR (SMD: 0.680; 95% CI: 0.101, 1.259; p = 0.021). However, subgroup analysis based on measuring process and patient characteristics showed that no significant differences were detected in nNO between AR patients with nasal polyps or sinusitis or marked ostial obstruction and healthy controls.

CONCLUSIONS

nNO is a potential indicator for recognizing AR. Nasal polyps, sinusitis and marked ostial obstruction should be considered before nNO is applied to detect AR.

Exhaled and Nasal Nitric Oxide - Impact for Allergic Rhinitis

FeNO measurement is a validated non-invasive technique, which is used for diagnosis and monitoring of asthma. It would be desirable to find a reliable method to monitor allergic rhinitis (AR) via measurement of FeNO, and/or nasal nitric oxide (nNO). The aim of our study was the assessment of the efficacy of FeNO and nNO as markers in AR treatment. FeNO and nNO were measured with the portable NO analyser (NIOX MINO®) in healthy participants and in patients with AR. The patients were examined during the pollen season and out of it. The effect of local corticosteroids and antihistamine therapy was observed in patients with AR during pollen season after three weeks of therapy. There are significant differences between FeNO and nNO in patients with AR compared to healthy controls at all set points of measurements. While FeNO responded well to the treatment with both antihistamines and combined therapy, nNO decreased only after combined therapy with antihistamines and nasal corticosteroids. nNO monitoring alone is not a suitable method to monitor inflammation of the upper airways in AR and its suppression by anti-allergic treatment and should be correlated with other markers as FeNO or symptom scores.

Nasal nitric oxide in relation to asthma characteristics in a longitudinal asthma cohort study

OBJECTIVE

Cross-sectional studies report relations between low nasal nitric oxide (nNO) and poor asthma control and between low nNO and chronic rhinosinusitis (CRS). In our cohort study, we studied if changes in nNO related to changes in asthma control, symptoms of CRS, or asthma or rhinitis medication.

METHODS

A total of 196 subjects with predominantly mild to moderate asthma, aged 10-35 years, performed nNO measurements at both baseline and follow-up after a median of 43 (range 23-65) months. Asthma control, CRS symptoms, and medication, were questionnaire-assessed at both timepoints. IgE sensitisation against aeroallergens was quantified at baseline.

RESULTS

There was an increase in nNO between baseline and follow-up (764 ± 269 ppb vs. 855 ± 288 ppb, p < 0.001). When adjusted for covariates, a larger increase in nNO was found in subjects sensitised to perennial aeroallergens than those not sensitised (92 (16-167) ppb), as well as in subjects with daily use of inhaled corticosteroids (ICS) at baseline but not at follow-up than those on ICS daily at both timepoints (146 (51-242) ppb). In the same model, subjects using nasal steroids daily at both timepoints had decreased nNO compared with those without such treatment at both timepoints (-185 (-321-(-48)) ppb). No relations between changes in nNO levels and changes in asthma control or symptoms of CRS were found.

CONCLUSION

Longitudinal changes in nNO were not related to changes in asthma control, but were related to changes in asthma or rhinitis medication.

Clinical application of nasal nitric oxide measurement in allergic rhinitis: A systematic review and meta-analysis

BACKGROUND

Nasal nitric oxide (nNO) is considered a biomarker of nasal inflammation.

OBJECTIVE

To perform a systematic review with meta-analysis and meta-regressions on the association between nNO levels and allergic rhinitis (AR).

METHODS

PubMed, Web of Science, Scopus, and EMBASE databases were systematically searched. Differences between cases and controls were expressed as standardized mean differences (SMD) with 95% confidence intervals (CI).

RESULTS

Overall, 39 articles were included: 30 containing data on nNO measured by nasal aspiration (1881 patients with AR and 1337 controls) and 12 assessing nNO by nasal exhalation (525 patients with AR and 350 controls). Compared with controls, AR presented significantly higher nNO values both during nasal aspiration (SMD, 1.309; 95% CI, 0.841-1.777; P < .001) and nasal exhalation (SMD, 0.708; 95% CI, 0.303-1.114; P = .001). Sensitivity and subgroup analyses confirmed that the results for the evaluated outcomes were not affected by the presence of clinical confounding factors (asthma, nasal polyps, inhaled corticosteroids, smoking history), this being valid for both perennial and seasonal diseases during exposure to allergens. For the aspiration method, meta-regressions indicated that older age and a better pulmonary function were associated with a lower difference in nNO levels between patients with AR and controls, whereas an increasing aspiration flow was associated with a high effect size.

CONCLUSION

nNO levels are higher in AR, particularly when using high aspiration flows and in younger patients, who often perceive this condition as a source of disability. Further studies are needed to evaluate the usefulness of this biomarker for monitoring airway disorders and optimizing strategies in different settings (community, hospital, rehabilitation).

Nasal Nitric Oxide in Chronic Rhinosinusitis with or without Nasal Polyps: A Systematic Review with Meta-Analysis

Background and Aims: There has been a recent growing interest in the role of nasal nitric oxide (nNO) as a biomarker for osteomeatal complex obstruction in paranasal sinus diseases. By using meta-analysis, we systematically reviewed the literature to establish the possible link between nNO concentration and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP). Methods: We systematically searched the EMBASE, PubMed, Scopus, and Web of Science databases for related studies. Differences between controls and cases were reported as standardized mean difference (SMD), with 95% confidence intervals (95% CI), using the random-effects method. Results: We selected 23 articles for the final analysis: 15 with data on 461 CRSwNP patients and 384 healthy controls, 10 with data on 183 CRSsNP patients and 260 controls, and 14 studies on 372 CRSwNP and 297 CRSsNP patients. CRSwNP patients showed significantly lower nNO values when compared to both healthy controls (SMD: −1.495; 95% CI: −2.135, −0.854; p < 0.0001) and CRSsNP patients (SMD: −1.448; 95% CI: −2.046, −0.850; p < 0.0001). Sensitivity and subgroup analyses confirmed the results, which were further refined by regression models. They showed that an increasing aspiration flow is related to a greater difference in nNO levels between cases and control subjects. We also documented lower nNO levels in CRSsNP patients with respect to controls (SMD: −0.696; 95% CI: −1.189, −0.202; p = 0.006), being this result no longer significant when excluding patients in therapy with intranasal corticosteroids. As shown by regression models, the increased Lund–Mackay score indicates a high effect size. Conclusions: nNO levels are significantly lower in CRSwNP, especially when using higher aspiration flows. Additional studies are needed to define one single standardized method and normal reference values for nNO.

Measurement of nasal and fractional exhaled nitric oxide in children with upper airway inflammatory disease: Preliminary results

OBJECTIVES

To assess the clinical significance of nasal nitric oxide (nNO) and fractional exhaled nitric oxide (FeNO) concentrations in children with upper airway inflammatory disease.

METHODS

Fifteen healthy children, 30 with allergic rhinitis (AR), 10 with non-allergic rhinitis (NAR), and 30 with sleep disordered breathing (SDB) were enrolled. The FeNO and nNO concentrations were measured non-invasively using a NIOX MINO system.

RESULTS

Both nNO and FeNO were significantly higher in children with AR than in healthy children (P=0.000 and P=0.000, respectively). Compared to healthy children, nNO was also significant higher in children with NAR (P=0.011) or SDB (P=0.027). In contrast, FeNO did not differ from controls in children with NAR or SDB.

CONCLUSIONS

Our data suggest that nNO has potential value for diagnosing upper airway inflammation. Moreover, elevated FeNO distinguishes allergic from non-allergic rhinitis.

Comparison of nasal nitric oxide levels between the inferior turbinate surface and the middle meatus in patients with symptomatic allergic rhinitis

BACKGROUND

Because of the anatomical complexity and the high output of the human nose, it has been unclear whether nasal nitric oxide (NO) serves as a reliable marker of allergic rhinitis (AR). We examined whether nasal NO levels in the inferior turbinate (IT) surface and the middle meatus (MM) differ in symptomatic AR patients.

METHODS

We measured fractional exhaled NO (FeNO) and nasal NO in normal subjects (n = 50) and AR patients with mild symptoms (n = 16) or moderate or severe symptoms (n = 27). Nasal NO measurements were obtained using an electrochemical analyzer connected to a catheter and an air-suction pump (flow rate 50mL/sec).

RESULTS

Compared to the normal subjects, the AR patients showed significantly higher nasal FeNO and nasal NO levels in the IT area. No significant difference in the MM area was observed among the three groups. The MM area showed higher NO levels than the IT area in all three groups. The ratio of nasal NO levels of the MM area to the IT area (MM/IT ratio) was significantly lower in the AR groups. The moderate/severe AR patients showed significantly higher nasal NO in the IT area (104.4 vs. 66.2ppb) and lower MM/IT ratios than those in the mild AR patients. The analysis of nasal brushing cells revealed significantly higher eosinophil cationic protein and nitrotyrosine levels in the AR groups.

CONCLUSIONS

Nasal NO assessment in the IT area directly reflects persistent eosinophilic inflammation and may be a valid marker to estimate the severity of AR.

Nasal nitric oxide in sleep-disordered breathing in children

BACKGROUND

Inflammation plays a role in the pathogenesis and consequences of sleep-disordered breathing (SDB). The nasal mucosa and paranasal sinuses produce high levels of nitric oxide (NO). In asthma, exhaled NO is a marker of airway inflammation. There is only limited information whether nasal NO (nNO) accompanies also chronic upper airway obstruction, specifically, SDB. The objective of this study was to investigate nNO levels in children with SDB in comparison to healthy non-snoring children.

METHODS

Nasal NO was measured in children who underwent overnight polysomnographic studies due to habitual snoring and suspected SDB and in healthy non-snoring controls.

RESULTS

One hundred and eleven children participated in the study: 28 with obstructive sleep apnea (OSA), 60 with primary snoring (PS), and 23 controls. Nasal NO levels were significantly higher in children with OSA and PS compared to controls (867.4 ± 371.5, 902.0 ± 330.9, 644.1 ± 166.5 ppb, respectively, p = 0.047). No difference was observed between children with OSA and PS. No correlations were found between nNO levels and any of the PSG variables, nor with age, BMI percentile or tonsils size.

CONCLUSIONS

Compared to healthy controls, nNO is increased in children with SDB, but it is not correlated with disease severity. This is probably due to the local mechanical processes and snoring.

Nasal nitric oxide is associated with exhaled NO, bronchial responsiveness and poor asthma control

The fraction of exhaled nitric oxide (FeNO) is an established marker of airway inflammation in asthma. Nasal nitric oxide (nNO) has initially been regarded as a promising marker of inflammation of nasal mucosa. However, due to its dual origins, paranasal sinuses and nasal mucosa, the clinical use of nNO is controversial. There is an inflammatory link between inflammation in the upper and lower airways within the united airways' paradigm, but the study of the clinical value of nNO in asthma has been limited. The objective of this study is to analyse nNO in asthmatics and its relationship to FeNO, bronchial hyperresponsiveness, allergic sensitization and asthma control. A total of 371 children and young adults from an asthma cohort were included in this study, which performed measurements of nNO (through aspiration at 5 mL s(-1)), FeNO, bronchial responsiveness to methacholine, blood eosinophil count (B-Eos) and IgE sensitization. The asthma control test (ACT) and a questionnaire regarding medical treatment, symptoms of asthma, rhinitis and chronic rhinosinusitis were completed by all subjects. An association was found between higher nNO levels and increased bronchial responsiveness (p < 0.001), FeNO (p < 0.001) and B-Eos (p = 0.002). Sensitization to furry animals related to higher levels of nNO (p < 0.001). Subjects with poorly controlled asthma (ACT < 15) had lower levels of nNO than subjects with a higher ACT score (619 ± 278 ppb, versus 807 ± 274 ppb, p = 0.002). Loss of smell showed the strongest association with lower nNO levels among the upper airway symptoms recorded. In patients with asthma, nNO was positively correlated with exhaled NO, bronchial responsiveness and asthma control. This study suggests clinical utility of nNO in subjects with asthma, but in order to get better understanding of the nNO determinants, simultaneous mapping of upper airway comorbidities by clinical examination is appropriate.

Exhaled nasal nitric oxide during humming: potential clinical tool in sinonasal disease?

The use of nasal nitric oxide (nNO) in sinonasal disease has recently been advocated as a potential tool to explore upper inflammatory airway disease. However, it is currently hampered by some factors including the wide range of measurement methods, the presence of various confounding factors and the heterogeneity of the study population. The contribution of nasal airway and paranasal sinuses communicating with the nose through the ostia represents the main confounding factor. There is accumulating evidence that nasal humming (which is the production of a tone without opening the lips or forming words) during nNO measurement increases nNO levels due to a rapid gas exchange in the paranasal sinuses. The aim of this review is to discuss the basic concepts and clinical applications of nNO assessment during humming, which represents a simple and noninvasive method to approach sinonasal disease.

Markers of upper airway inflammation associated with microbial exposure and symptoms in occupants of a water-damaged building

BACKGROUND

Water damage in buildings has been associated with reports of upper airway inflammation among occupants.

METHODS

This survey included a questionnaire, allergen skin testing, nasal nitric oxide, and nasal lavage on 153 participants. We conducted exposure assessments of 297 workstations and analyzed collected dust for fungi, endotoxin, and (1 → 3)-β-D-glucan to create floor-specific averages.

RESULTS

Males had higher levels of nasal inflammatory markers, and females reported more symptoms. ECP, IL-8, and MPO were significantly associated with nasal symptoms, flu-like achiness, or chills. Fungi and glucan were positively associated with blowing out thick mucus. Endotoxin was significantly associated with ECP in overall models, and with ECP, IL-8, MPO, and neutrophils among non-atopic females.

CONCLUSIONS

In this study, we documented an association between endotoxin and nasal inflammatory markers among office workers. The results of our study suggest that a non-allergic response may contribute to symptoms occurring among occupants in this water-damaged building.

Nasal and exhaled nitric oxide in allergic rhinitis

Objectives

The primary aim of this study was to assess whether one can use levels of nasal nitric oxide (nNO) and exhaled nitric oxide (eNO) as a means of evaluation in allergic rhinitis.

Methods

We used a chemiluminescence analyzer to measure nNO and eNO in normal controls (n=34) and allergic rhinitis patients (n=35), and compared these measurements with various parameters of clinical symptoms and laboratory data.

Results

Mean nNO (389±119 ppb) in allergic rhinitis patients was significantly higher than normal controls (276±88 ppb). Without asthma, mean eNO (64.8±55.9 ppb) in allergic rhinitis patients was significantly higher than normal controls (33.0±24.0 ppb). In the persistent allergic rhinitis group, eNO concentration was significantly higher, while nNO concentration was significantly lower than the intermittent group.

Conclusion

We can use nNO and eNO levels for evaluation of allergic rhinitis. However, we should consider the fact that nNO levels can be reduced, when symptoms are severe and long-lasting. Additionally, in allergic rhinitis, eNO can be elevated without asthma.

Measurements of nasal fractional exhaled nitric oxide with a hand-held device in patients with allergic rhinitis: relation to cedar pollen dispersion and laser surgery

BACKGROUND

There has been an increasing interest in monitoring the fractional concentrations of exhaled NO (FeNO) levels in allergic rhinitis (AR) patients. In the present study, we examined whether the nasal FeNO measurement might reflect the degree of local allergic inflammation as well as subjective symptoms.

METHODS

The FeNO measurement was performed using a handheld electrochemical analyzer (NObreath®) with a nose adaptor. In the cross-sectional study, 56 patients with perennial AR patients, 18 AR patients with bronchial asthma (BA), 12 patients with vasomotor rhinitis, and 30 normal subjects were enrolled. For the follow-up study, 12 seasonal allergic rhinitis (SAR) patients against Japanese cedar and 10 perennial AR patients who underwent laser surgery were examined.

RESULTS

The AR patients and vasomotor rhinitis patients showed significantly higher oral FeNO levels as compared with the normal subjects. The nasal FeNO levels were significantly higher in the perennial AR patients with or without BA than in the normal subjects and vasomotor rhinitis patients. There were positive correlations between the nasal symptom scores and FeNO levels. The SAR patients showed a significant decrease in the nasal FeNO level after the pollen dispersion season. In addition, the therapeutic effects of laser surgery in the AR patients accompanied a significant reduction in the nasal FeNO levels one month after treatment.

CONCLUSIONS

The nasal FeNO measurement by NObreath® is easy to perform and suitable for monitoring AR patients in various treatment modalities. Furthermore, it may have potential usefulness as a tool to improve daily clinical care.

Clara cell protein in nasal lavage fluid and nasal nitric oxide - biomarkers with anti-inflammatory properties in allergic rhinitis

Background

Clara cell protein (CC16) is ascribed a protective and anti-inflammatory role in airway inflammation. Lower levels have been observed in asthmatic subjects as well as in subjects with intermittent allergic rhinitis than in healthy controls. Nasal nitric oxide (nNO) is present in high concentrations in the upper airways, and considered a biomarker with beneficial effects, due to inhibition of bacteria and viruses along with stimulation of ciliary motility. The aim of this study was to evaluate the presumed anti-inflammatory effects of nasal CC16 and nNO in subjects with allergic rhinitis.

Methods

The levels of CC16 in nasal lavage fluids, achieved from subjects with persistent allergic rhinitis (n = 13), intermittent allergic rhinitis in an allergen free interval (n = 5) and healthy controls (n = 7), were analyzed by Western blot. The levels of nNO were measured by the subtraction method using NIOX^®. The occurrences of effector cells in allergic inflammation, i.e. metachromatic cells (MC, mast cells and basophiles) and eosinophils (Eos) were analyzed by light microscopy in samples achieved by nasal brushing.

Results

The levels of CC16 correlated with nNO levels (r² = 0.37; p = 0.02) in allergic subjects.

The levels of both biomarkers showed inverse relationships with MC occurrence, as higher levels of CC16 (p = 0.03) and nNO (p = 0.05) were found in allergic subjects with no demonstrable MC compared to the levels in subjects with demonstrable MC. Similar relationships, but not reaching significance, were observed between the CC16 and nNO levels and Eos occurrence. The levels of CC16 and nNO did not differ between the allergic and the control groups.

Conclusions

The correlation between nasal CC16 and nNO levels in patients with allergic rhinitis, along with an inverse relationship between their levels and the occurrences of MC in allergic inflammation, may indicate that both biomarkers have anti-inflammatory effects by suppression of cell recruitment. The mechanisms behind these observations warrant further analyses.

Expression of nitric oxide synthases in leukocytes in nasal polyps

BACKGROUND

Nitric oxide (NO) has various roles in airway physiology and pathophysiology. Monitoring exhaled NO levels is increasingly common to measure airways inflammation and inhaled NO studied for its therapeutic value in premature infants and adult respiratory distress syndrome. NO is produced by 3 isoforms of NO synthase (NOS1, 2, 3), and each can play distinct and perhaps overlapping roles in the airways. However, the distribution, regulation, and functions of NOS in various cells in the upper airways, particularly in leukocytes, are incompletely understood.

OBJECTIVE

To characterize the expression of NOS isoforms in leukocytes in normal middle turbinate tissues (MT) and in inflammatory nasal tissue (nasal polyps, NP).

METHODS

Normal MT tissue was collected from surgical specimens that were to be discarded. The NP samples were from surgical tissue archives of 15 patients with chronic rhinosinusitis. Isoforms of NOS in cells were identified by double immunostaining using NOS isoform-specific and leukocyte-specific (mast cell, eosinophil, macrophage, neutrophil, or T cell) antibodies.

RESULTS

The proportion of total cells below the epithelium that were positive for each isoform of NOS was higher in NP than in MT. Each isoform of NOS was found in all leukocyte populations studied, and there were significant differences in the percentage of leukocytes expressing NOS isoforms between MT and NP.

CONCLUSION

All isoforms of NOS are expressed in leukocytes in MT and NP, and their expression varies among leukocyte types. Our data provide a basis to investigate the regulation, cell distribution, and distinct functions of NOS isoforms in normal and inflamed nasal tissues.

Hand-held nitric oxide sensor NIOX MINO® for the monitoring of respiratory disorders

Measurements of exhaled nitric oxide have been proposed as a tool to improve the control of asthma and inflammatory airways disease, including the patient's response to anti-inflammatory treatment and to predict loss of control and to monitor compliance with treatment. Several techniques have been used to assess exhaled nitric oxide gas and the majority of studies have used the chemiluminescence method. More recently, a new hand-held electrochemical sensor NIOX MINO(®) has been developed. Here, we will review the use of the NIOX MINO for the study of respiratory disorders.

Acoustic rhinometry, spirometry and nitric oxide in relation to airway allergy and smoking habits in an adolescent cohort

OBJECTIVE

This study aimed to analyze upper and lower airway function and the impact of smoking habits in a cohort of allergic and healthy adolescents. The influence of smoking habits on the outcomes of rhinitis and asthma is well documented, but only few reports are available showing smoke related upper airway impairment by rhinometric measurements, and none with focus on early changes in adolescents.

METHODS

A cohort followed from infancy was re-examined at the age of 18 years concerning allergy development. Acoustic rhinometry (VOL2), spirometry (FEV(1)) and measurements of nitric oxide levels from the upper (nNO) and lower airways (eNO) were performed before and after physical exercise, and smoking habits were registered.

RESULTS

Active smoking habits were reported by 4/21 subjects suffering from allergic rhinitis, by 1/4 from probable allergic rhinitis, by 0/3 subjects with atopic dermatitis and by 2/10 healthy controls. Smoking habits were reported as daily by 2 and occasional by 5 of the 7 active smokers. VOL2 did not increase in smokers after exercise as in non-smokers, resulting in a post-exercise group difference (7.3±1.1cm(3) vs. 8.8±1.5cm(3); p=0.02), and FEV(1) values were lower in smokers compared to non-smokers (89±7% vs. 98±8%; p=0.02). The nNO and eNO levels were, however, only slightly reduced in smokers. Airway allergy was discerned only in subjects with current allergen exposure by increased eNO levels compared to healthy controls (41±44ppb vs. 13±5ppb). The levels of VOL2, nNO and FEV(1) did not differentiate allergic subjects from healthy controls.

CONCLUSIONS

Low levels of tobacco smoke exposure resulted in reduced airway functions in this adolescent cohort. Acoustic rhinometry and spirometry were found to be more sensitive methods compared to nitric oxide measurements in early detection of airway impairment related to smoke exposure. A possible difference in airway vulnerability between allergic and healthy subjects due to smoke exposure remains to be evaluated in larger study groups.

Relationship between fractional exhaled nitric oxide and nasal nitric oxide in airways disease

BACKGROUND

Invasive techniques show evidence of a unified allergic airway. Nitric oxide is measured noninvasively from the lungs (fractional exhaled nitric oxide [FeNO]) and nose (nasal nitric oxide [nNO]).

OBJECTIVE

To investigate the relationship between FeNO and nNO in different airway conditions.

METHODS

A total of 227 participants were assessed: 41 healthy volunteers (HVs), 33 patients with asthma, 52 patients with allergic rhinitis (AR), 63 with unified airway disease (UAD), and 38 with nasal polyposis (NP). Correlation and multiple linear regression analyses were performed.

RESULTS

Geometric means (95% confidence intervals) for FeNO were as follows: 14.7 (12.4-17.5) ppb for HVs, 29.0 (22.5-37.4) ppb for asthma patients, 23.1 (19.0-28.1) for AR patients, 27.2 (23.0-32.4) for UAD patients, and 28.5 (21.5-37.8) for NP patients. For nNO, the values were as follows: 878.1 (807.0-955.6) ppb for HVs, 674.1 (557.4-815.1) for asthma patients, 853.3 (778.8-934.8) ppb for AR patients, 763.4 (694.1-839.5) for UAD patients, and 388.6 (317.9-474.9) for NP patients. The nNO was lower in the NP group than the other groups (P < .001). The nNO and FeNO were correlated in the AR patients (r = 0.56; P < .0001) and HVs (r = 0.44; P = .004) but not significantly in the other groups. Multiple linear regression of the whole cohort demonstrated that after diagnosis, age, sex, and inhaled corticosteroids were taken into account nNO had a significant association with FeNO (P = .02).

CONCLUSION

Reduced nNO in NP patients is due to ostiomeatal complex obstruction. FeNO is sensitive to suppression by inhaled corticosteroids. The AR and HV groups have no such confounders; hence, correlation is most evident. Exclusion of confounders reveals a correlation between upper and lower airway inflammation with noninvasive techniques.

Increased exhaled nitrite in children with allergic asthma is not related to nitric oxide formation

INTRODUCTION

Nitrite sampled from the upper airways could originate from inflammation-induced nitric oxide (NO), as reports of elevated nitrite in exhaled breath condensate (EBC) from asthmatics suggest, but also through bacterial action in the pharyngo-oral tract.

OBJECTIVES

To correlate EBC nitrite and nitrate to exhaled NO (FENO, fraction of expired NO) and other markers of disease activity in children with allergic asthma and thereby further investigate their role and origin.

MATERIALS AND METHODS

EBC was collected from 27 asthmatic subjects (ages 6-17 years, all immunoglobulin E-positive for aeroallergens) and 21 age-matched non-atopic healthy controls for fluorometric analysis of nitrite and nitrate. These markers were compared with measurements of FENO, blood eosinophil count (EOS), methacholine reactivity (PD(20)) and baseline spirometry.

RESULTS

EBC nitrite, in contrast to nitrate, was significantly increased (P < 0.01) in the asthmatic children. They also had increased levels of FENO (P < 0.001) and EOS (P < 0.001) along with decreased PD(20) (P < 0.001) and FEV1/FVC (P < 0.01). However, there was no correlation between EBC nitrite and FENO (r = 0.05) or any other marker of disease activity in the asthmatic children, whereas between the other markers correlations could be established.

CONCLUSION

EBC nitrite is elevated in childhood asthma but the lack of correlation to FENO and other markers, together with simultaneously normal levels of nitrate, make its origin as a metabolite of inflammation-induced NO questionable.

Noninvasive methods for assessment of airway inflammation in occupational settings

The present document is a consensus statement reached by a panel of experts on noninvasive methods for assessment of airway inflammation in the investigation of occupational respiratory diseases, such as occupational rhinitis, occupational asthma, and nonasthmatic eosinophilic bronchitis. Both the upper and the lower airway inflammation have been reviewed and appraised reinforcing the concept of 'united airway disease' in the occupational settings. The most widely used noninvasive methods to assess bronchial inflammation are covered: induced sputum, fractional exhaled nitric oxide (FeNO) concentration, and exhaled breath condensate. Nasal inflammation may be assessed by noninvasive approaches such as nasal cytology and nasal lavage, which provide information on different aspects of inflammatory processes (cellular vs mediators). Key messages and suggestions on the use of noninvasive methods for assessment of airway inflammation in the investigation and diagnosis of occupational airway diseases are issued.

Nasal nitric oxide and regulation of human pulmonary blood flow in the upright position

There are a number of evidences suggesting that lung perfusion distribution is under active regulation and determined by several factors in addition to gravity. In this work, we hypothesised that autoinhalation of nitric oxide (NO), produced in the human nasal airways, may be one important factor regulating human lung perfusion distribution in the upright position. In 15 healthy volunteers, we used single-photon emission computed tomography technique and two tracers (99mTc and 113mIn) labeled with human macroaggregated albumin to assess pulmonary blood flow distribution. In the sitting upright position, subjects first breathed NO free air through the mouth followed by the administration of the first tracer. Subjects then switched to either nasal breathing or oral breathing with the addition of exogenous NO-enriched air followed by the administration of the second tracer. Compared with oral breathing, nasal breathing induced a blood flow redistribution of ∼4% of the total perfusion in the caudal to cranial and dorsal to ventral directions. For low perfused lung regions like the apical region, this represents a net increase of 24% in blood flow. Similar effects were obtained with the addition of exogenous NO during oral breathing, indicating that NO and not the breathing condition was responsible for the blood flow redistribution. In conclusion, these results provide evidence that autoinhalation of endogenous NO from the nasal airways may ameliorate the influence of gravity on pulmonary blood flow distribution in the upright position. The presence of nasal NO only in humans and higher primates suggest that it may be an important part of the adaptation to bipedalism.

The minimal clinically important difference in allergic rhinitis

BACKGROUND

When presented with results from clinical measurements or research findings, clinicians must first make an interpretation of their importance, not only in statistical terms, but also the 'clinical importance' given the size of the change observed. To do this, they require an understanding of the relationship between their outcome measures, and the patient's perception of change. The minimal clinically important difference (MCID) illustrates this relationship by calculating the smallest change in a given outcome that is meaningful to a patient. There are few reports of calculated MCIDs in the Rhinology literature.

OBJECTIVE

To calculate MCIDs for common subjective and objective outcome measures in allergic rhinitis (AR).

METHODS

Nine randomized, blinded, placebo-controlled clinical trials in intermittent and persistent AR (pooled subjects, n=204) were analysed using anchor- and distribution-based approaches, applying regression and meta-analysis techniques.

RESULTS

MCIDs were obtained for the Mini Rhinoconjunctivitis Quality of Life Questionnaire: 0.4 units, peak nasal inspiratory flow: 5 L/min and total nasal symptoms score: 0.55 units. Nasal NO measurement changes had no correlation with patient perceptions of benefit.

CONCLUSION

Estimates of MCIDs were obtained for common subjective and objective rhinological outcomes. MCIDs can and should be applied by physicians interpreting research findings, as well as researchers reporting their findings. We can then be confident that our changes in practice will be of perceptible benefit to the patient.

Evidence-based recommendations regarding the differential diagnosis and assessment of nasal congestion: using the new GRADE system

Nasal congestion is an important symptom in nasal pathology and can be defined as an objective restriction of nasal cavity airflow because of mucosal pathology and/or increased mucus secretion (excluding anatomical variants). Using the new Grading Recommendations Assessment, Development and Evaluation system, evidence-based recommendations are made that will encompass different clinical questions regarding diagnostic modalities of nasal congestion: (i) their usefulness in assessment of presence and severity of congestion; (ii) their usefulness in assessment of etiological pathology responsible for congestion; and (iii) their usefulness in follow up and treatment effectiveness evaluation of nasal congestion.

Complementary therapy in allergic rhinitis

The term complementary/alternative medicine (CAM) refers to those therapeutic and diagnostic approaches different from conventional allopathic medicine. CAM may encompass homeopathy, acupuncture, phytotherapy, antioxidant therapy, and numerous holistic or behavioral techniques. Allergists and physicians of all disciplines are confronted with patients using CAM treatments, making it imperative that they become familiar with the scientific literature surrounding them. Given the high prevalence of allergic diseases and associated costs of CAM treatments, proof of CAM therapies is needed to establish appropriate guidelines for their use. Efficacy of CAM modalities should be established with randomized, double-blind, placebo-controlled trials, including adverse-effects monitoring. Of all the CAM therapies examined to treat allergic rhinitis, some herbal therapies and antioxidants demonstrate a trend toward some clinical efficacy. Researchers have yet to determine how to integrate these CAM modalities into the general treatment paradigm of allergic rhinitis.

Nitric oxide in the airways

PURPOSE OF REVIEW

This review briefly explains the basic facts about nitric oxide, which is entering clinical practice as a measure of lower airways inflammation and is likely also to be employed in otorhinolaryngological practice.

RECENT FINDINGS

These include the validity of nasal nitric oxide in diagnosing primary ciliary dyskinesia and in monitoring the response to chronic rhinosinusitis therapy. The nasal nitric oxide value combined with a humming manoeuvre, which increases the passage of nitric oxide from the sinuses to the nose if the ostiomeatal complex is patent, could reduce the need for computed tomography scans. The link between nitric oxide production and ciliary beating requires further exploration. Therapeutic adjustments to nitric oxide production are under investigation.

SUMMARY

Nitric oxide is likely to prove highly relevant to airways defence, as well as being an inflammatory mediator. Nasal nitric oxide probably explains some of the benefit of nasal rather than mouth breathing.

The effect of allergic rhinitis on adenosine concentration in exhaled breath condensate

BACKGROUND

Patients with allergic rhinitis (AR) frequently develop asthma. This initiating inflammation in the lower airways may result in increased levels of inflammatory mediators such as adenosine in the exhaled breath.

OBJECTIVE

We compared adenosine levels in exhaled breath condensate (EBC) and both exhaled and nasal nitric oxide (NO) levels of AR patients and healthy control subjects. We also tested whether inhalation through inflamed nasal cavity during EBC sampling influences adenosine concentrations in exhaled air.

METHODS

Exhaled and nasal NO levels were measured and EBC samples (at oral inhalation) were collected from 27 patients and 15 healthy controls. EBC collection was repeated after 15 min with subjects inhaling through their nose. Adenosine was measured by HPLC and NO was determined by chemiluminescence.

RESULTS

The concentration of EBC adenosine was higher in patients with AR than in healthy controls (12.4+/-1.3 nM vs. 6.5+/-0.7 nM, P=0.0019) and this was accompanied by an increase in the concentration of exhaled NO (10.2+/-1.3 ppb vs. 5.3+/-0.5 ppb; P=0.0099, respectively). No difference in nasal NO was detected. EBC adenosine concentration showed a significant positive correlation with the level of exhaled NO. In contrast to healthy control subjects, patients with rhinitis had higher levels of exhaled adenosine when inhaling via the nose instead of the mouth (17.7+/-2.8 nM, P=0.007).

CONCLUSION

When compared with healthy subjects, patients with AR exhibit an increased concentration of exhaled adenosine and a related increase in exhaled NO concentration. EBC adenosine is further increased when rhinitis patients inhale through their nose than via their mouth. Our data suggest that non-asthmatic patients with rhinitis may have subclinical inflammation in their lower airways.

Exhaled nasal nitric oxide output is reduced in humans at night during the sleep period

The physiologic function of nasal nitric oxide (NO) release is unknown. In prior experiments, topical NG-nitro-L-arginine methyl ester (L-NAME) on nasal mucosa reduced exhaled nasal NO output and caused daytime sleepiness. We hypothesized that nasal NO output is reduced at night during the sleep period. We measured exhaled nasal NO concentration and minute ventilation and calculated nasal NO output in humans over 24 h. Daytime awake NO output was greater than NO output at night during sleep or transient wakefulness. Exhaled NO concentration decreased during sleep along with minute ventilation. A daytime voluntary reduction in minute ventilation also decreased nasal NO output but exhaled NO concentration increased. Nasal NO output was not changed by body position. We conclude that exhaled nasal NO output is decreased at night due to decreased mass flow of NO into nasal air in addition to decreased minute ventilation. Our findings suggest a role of nasal NO in sleep or in the physiologic processes accompanying sleep.

Nasal nitric oxide and nasal allergy

Measurements of nasal nitric oxide (nNO) are attractive because they are completely noninvasive and can easily be performed. The measurements may be useful in the early diagnosis of patients with chronic airway disorders such as Kartager's syndrome and cystic fibrosis. The possible use of nNO measurements in the diagnosis and treatment of allergic rhinitis still needs to be further evaluated because of the variable and also contradicting findings of nNO concentrations in this disease. In this review we will discuss the origin, production and measurement of nNO as well as the effect of allergic rhinitis, nasal allergen challenge and medication on nNO. Subsequently, we examine published data on allergic rhinitis and nNO, and summarize the effect of treatment of rhinitis on nNO. Finally, we discuss the potential future role for nNO in the diagnosis and management of allergic rhinitis.

Nasal NO measurement by direct sampling from the nose during breathhold: aspiration flow, nasal resistance and reproducibility

The objective of this study was assessment of the effect of aspiration flow, the nasal cycle, and time on nasal nitric oxide (nNO) concentrations in air sampled from one nostril during breathhold. nNO was measured in 45 healthy subjects (19 males, aged 18-45 years) from one nostril during breathholding. We compared nNO values and time to plateau in both nostrils with 3 aspiration flows (280, 700, 1,200 ml/min) and assessed the short-term and long-term reproducibility. Mean nNO values at flows of 280, 700 and 1,200 ml/min differed significantly (P < 0.01): 854, 474, 380 ppb, respectively. The (median) plateau was reached after 6, 4 and 3 s for the different flows. The within-subject coefficient of variability was always < 5%. We found no difference in nNO between left-, right-, largest or smallest nostril (P > 0.10). nNO values after 6, 24 h and 7 days were not significantly different from baseline (P > 0.10) and showed fair reproducibility. The highest aspiration flow was experienced as unpleasant. nNO can be measured in either nostril and shows no diurnal variation. The measurement is quick, reproducible, feasible and best accepted with an aspiration flow of 700 ml/min during breathhold for 10 s.

Determinants of increased exhaled nitric oxide in patients with suspected asthma

Exhaled nitric oxide (FENO) has been proposed as a marker of asthmatic inflammation, but it is unclear whether FENO in clinical use selects patients primarily according to their atopic or asthmatic status. The aim of this study was to investigate the determinants of increased FENO in patients with suspected asthma, by means of multinomial logistic regression analysis. The FENO of 132 patients referred because of symptoms suggestive of asthma were studied, and the explanatory factors tested included atopy according to prick skin tests, clinical asthma according to lung function tests, sputum eosinophilia and bronchial hyperresponsiveness (BHR). Slightly elevated FE(NO) levels were significantly explained only by sputum eosinophilia (OR: 3.7; 95% CI: 1.1-13.1; P=0.04), but for high levels of FE(NO) (> or =3 SD of predicted), clinical asthma (OR: 16.3; 95% CI: 5.4-49.7; P <0.0001) and sputum eosinophilia (OR: 12.0; 95% CI: 4.1-35.0; P >0.0001) were the characteristics with the highest prediction, followed by atopy and BHR. A significant interaction between asthma and atopy was observed relating to the effect on high FENO, but further analyses stratified by atopy showed significant associations between asthma and high FENO both in atopic and nonatopic patients. We conclude that in patients with symptoms suggesting asthma, slightly elevated and high levels of FENO are associated with sputum eosinophilia, whereas asthma is significantly associated only with high levels of FENO, irrespective of atopy. The results suggest that FENO is primarily a marker of airway eosinophilia, and that only high values of FENO may be useful to identify patients with atopic or nonatopic asthma.

Exhaled nitric oxide in asthmatic children and adolescents after nasal allergen challenge

Epidemiological data suggest a comorbidity link between nasal and bronchial allergic disease. Exhaled nitric oxide (FENO) is a sensitive marker of bronchial inflammation and increases after bronchial allergen provocation. We studied FENO in 19 children and adolescents with allergic asthma and 10 controls before and 2, 6 and 24 h after a single nasal allergen challenge. The correlation between FENO and other markers of allergic inflammation, such as eosinophils in blood and eosinophil cationic protein (ECP) in serum and nasal lavage was also assessed. FENO remained unchanged 24 h post-challenge in both steroid and steroid-naive patients. At 6 h post-challenge, FENO decreased in both asthmatics and controls. The asthmatic subjects showed a positive correlation between FENO and blood eosinophils before (r=0.71, p=0.001) and after the challenge, and between FENO and ECP in nasal lavage (r=0.62, p=0.02) 2 h after the challenge. Mean ECP in nasal lavage increased post-challenge but not significantly. We conclude that a single nasal allergen challenge does not augment bronchial inflammation although FENO, is related to blood eosinophil count and to the nasal inflammatory response. Our data do not support the theory of a direct transmission of the nasal inflammation to the lower airways.

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.