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

Fractional Exhaled Nitric Oxide as a Marker of Mucosal Inflammation in Chronic Rhinosinusitis

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a cost-effective, noninvasive point-of-care test that has proven valuable in identifying patients with lower airway inflammation and predicting the likelihood of responsiveness to inhaled corticosteroid therapy in asthma. The utility of FeNO in upper airway disease, specifically in CRS, remains to be determined.

OBJECTIVE

The goal of this study was to test whether FeNO could serve as a noninvasive marker of sinonasal mucosal inflammation in CRS patients.

METHODS

FeNO was obtained using a nitric oxide analyzer (NIOX VERO) as well as nasal mucus, the 22-item Sinonasal Outcome Test (SNOT-22), University of Pennsylvania Smell Identification Test (UPSIT), and Lund-Kennedy endoscopic scores concurrently in 112 CRS patients. Nasal mucus was analyzed for cytokine expression using solid-phase sandwich ELISA. Linear regression with Spearman correlation coefficient was used to determine strength of relationship between variables.

RESULTS

CRS patients showed elevated FeNO levels with asthma (47.12 ± 5.21 ppb) or without asthma (43.24 ± 9.810 ppb). Elevated FeNO levels correlated with sinonasal mucosal inflammation, as determined by increased levels of CCL26 and TNFα in nasal mucus obtained from CRS patients. Furthermore, elevated FeNO levels selectively correlated with worsened SNOT-22 nasal symptoms (P = 0.03) and Lund-Kennedy endoscopic scores (P = 0.007), but did not correlate with UPSIT scores.

CONCLUSIONS

FeNO levels correlated with increased sinonasal mucosal inflammation and symptom severity in CRS regardless of asthma status. FeNO measurements may serve as a quick and noninvasive marker in evaluating CRS patients.

Nasal nitric oxide measurement variability to establish a standard for reliable results

Nasal nitric oxide (nNO) measurement is a first-line test used to increase the post-measurement probability of primary ciliary dyskinesia (PCD) in subjects with symptoms consistent with this diagnosis [1]. The accuracy of nNO measurement is essential since it will orientate the work-up towards tests that are usually highly specialised and sometimes invasive. Accuracy of biological measurements relies on the technical and on the biological variability. While the accuracy of NO analysers is known better for chemiluminescence devices (e.g. <1 ppb with 1% linearity from 0.1 to 5000 ppb for CLD 88 (Eco Medics, Duernten, Switzerland)) than for widely used electrochemical devices (e.g. ±5 ppb for values <50 ppb and 10% for values >50 ppb for Niox Vero (Circassia, Oxford, UK)) [2], little is known on the biological variability of nNO measurements, except for increased nNO output variability in adults with rhinitis compared with healthy subjects and the positive effect of training on the level of nNO taken during expiration against a resistance (nNO-ER) in children [3, 4].

A repeatability of 10% for NO measurements obtained with the velum closed in the same or both nostrils is relevant, while measurements taken during tidal breathing should aim for a repeatability of 20% and 30%, respectivelyhttps://bit.ly/3sMnug6

An international survey on nasal nitric oxide measurement practices for the diagnosis of primary ciliary dyskinesia

Nasal nitric oxide (nNO) measurements are routinely used in the assessment of patients suspected to have primary ciliary dyskinesia (PCD), but recommendations for performing such measurements have not focused on children and do not include all current practices. To guide the development of a European Respiratory Society-supported technical standard for nNO measurements in children, an international online survey was conducted to better understand current practices for measuring nNO among providers involved in PCD diagnostics.

Seventy-eight professionals responded, representing 65 centres across 18 countries, mainly located in Europe and North America. Nearly all centres measured nNO in children and more than half of them performed measurements before 5-years of age. The test was often postponed in children with signs of acute airway infection. In Europe, the electrochemical technique was more frequently used than chemiluminescence. A similar proportion of centres performed measurements during exhalation against a resistance (49/65) or during tidal breathing (50/65) with 15 centres using only exhalation against a resistance and 15 centres using only tidal breathing. The cut-off values used to discriminate PCD was consistent across centres using chemiluminescence analyzers and these centres reported results as an output (nL.min−1). However, cut-off values were highly variable across centres using electrochemical devices, and nNO concentrations were typically reported as ppb.

This survey represents the first to determine real-world use of nNO measurements worldwide and revealed remarkable variability in methodology, equipment, and interpretation. These findings will be useful to standardise methods and training.

Nasal Nitric Oxide Measurement in Primary Ciliary Dyskinesia. A Technical Paper on Standardized Testing Protocols

Nasal nitric oxide concentrations are extremely low in primary ciliary dyskinesia (PCD), and measurement of this nasal gas is recommended as a PCD diagnostic test in cooperative patients aged 5 years and older. However, nasal nitric oxide measurements must be performed with chemiluminescence analyzers using a standardized protocol to ensure proper results, because nasal nitric oxide values can be influenced by various internal and external factors. Repeat nasal nitric oxide testing on separate visits is required to ensure that low diagnostic values are persistent and consistent with PCD. This technical paper presents the standard operating procedures for nasal nitric oxide measurement used by the PCD Foundation Clinical and Research Centers Network at various specialty centers across North America. Adherence to this document ensures reliable nasal nitric oxide testing and high diagnostic accuracy when employed in a population with appropriate clinical phenotypes for PCD.

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.

Measuring nasal nitric oxide in allergic rhinitis patients

OBJECTIVE

This study aimed to compare two sampling methods for nasal nitric oxide in healthy individuals and allergic rhinitis patients, and to examine the within-subject reliability of nasal nitric oxide measurement.

METHODS

The study included 23 allergic rhinitis patients without concomitant asthma and 10 healthy individuals. For all participants, nitric oxide levels were measured non-invasively from the lungs through the mouth (i.e. the oral fractional exhaled nitric oxide) and the nose. Nasal nitric oxide was measured by two different methods: (1) nasal aspiration via one nostril during breath holding and (2) single-breath quiet exhalation against resistance through a tight facemask (i.e. the nasal fractional exhaled nitric oxide).

RESULTS

Compared with healthy participants, allergic rhinitis patients had significantly higher average oral and nasal nitric oxide levels. All methods of nitric oxide measurement had excellent reliability.

CONCLUSION

Nasal nitric oxide measurement is a useful and reliable clinical tool for diagnosing allergic rhinitis in patients without asthma in an out-patient setting.

Intranasal odorant concentrations in relation to sniff behavior

Knowledge on how odorants are transported through the nasal cavity to the olfactory epithelium is limited. One facet of this is how the sniffing behavior affects the abundance of odorants transferred to the olfactory cleft and in turn influences odor perception. A novel system that couples an online mass spectrometer with an odorant pulse delivery olfactometer was employed to characterize intranasal odorant concentrations of butane-2,3-dione (or butanedione, commonly known as diacetyl) at the interior naris and the olfactory cleft. Volunteers (n=12) were asked to perform different modes of sniffing in relation to the sniff intensity that were categorized as 'normal', 'rapid' and 'forced'. The highest concentrations of butanedione at both positions in the nose were observed during normal sniffing, with the lowest concentrations correlating with periods of forced sniffs. This corresponded to the panelists' ratings that normal sniffing elicited the highest odor intensities. These feasibility assessments pave the way for more in-depth analyses with a variety of odorants of different chemical classes at various intranasal positions, to investigate the passage and uptake of odorants within the nasal cavity.

Clinical application of nasal nitric oxide measurement in pediatric airway diseases

Nitric oxide plays an important role in several physiological and pathophysiological processes in the respiratory tract. Different ways to measure nasal nitric oxide levels in children are currently available. The possibility of obtaining nasal nitric oxide measurement from relatively young children, combined with the availability of portable devices that can be used even in the office setting, opens new perspectives for nasal nitric oxide analysis in the pediatric daily practice. This review presents a synopsis about the current clinical applications of nasal nitric oxide measurement in the pediatric clinical practice. A total of 3,775 articles on the topic were identified, of which 883 duplicates were removed, and 2,803 were excluded based on review of titles and abstracts. Eighty-nine full text articles were assessed for eligibility and 32 additional articles were obtained from the reference lists of the retrieved studies. Since very low nasal nitric oxide levels are found in the majority of patients with primary ciliary dyskinesia, most publications support a central role for nasal nitric oxide to screen the disease, and indicate that it is a very helpful first-line tool in the real-life work-up in all age groups. Decreased nasal nitric oxide concentration is also typical of cystic fibrosis, even though nasal nitric oxide is not as low as in primary ciliary dyskinesia. In other upper airway disorders such as allergic rhinitis, rhinosinusitis, nasal polyposis, and adenoidal hypertrophy, clinical utility of nasal nitric oxide is still critically questioned and remains to be established. Since nNO determination is flow dependent, a general consensus from the major investigators in this area is highly desirable so that future studies will be performed with the same flow rate. A shared nNO methodology will enable to overcome the challenges that lie ahead in incorporating nNO measurement into the mainstream clinical setting of pediatric airway diseases.

Spectral Estimation of Nasal Cyclic Rhythm by Nasal Airflow Temperature Measurement

.The nasal cycle is referred to a cyclic fluctuation in congestion of the nasal mucosa that results in rhythmic and bilateral reciprocal alteration of nasal airway patency. The purpose of this study is to deal with statistical and power spectral analysis of nasal cycle by measuring the temperature difference between the airflow of both left and right nostrils. Five adult voluntary healthy subjects are enrolled for the study. Nasal temperature probe combined with amplifier are used for recording nasal airflow temperature on both nostrils. The highest nasal airflow temperature values are detected at the end of expiration and the lowest values are detected at the end of inspiration. Nasal cycle found in all the subjects and lasted to the minimum of 30 minutes to maximum of 6 hours. The difference in temperature of both nostrils is statistically significant (p<0.05) and spectral estimation is made using autoregressive modeling. The method is used to quantify nasal obstruction in pathological condition and also to correlate the related physiological phenomenon.

A human study model for nitric oxide research in sinonasal disease

Sinus nitric oxide (NO) measurements present a novel and promising approach to help overcome difficulties and confounding variables associated with nasal NO measurements such as the nasal cycle, ostial patency, and individual contribution to total NO production of each sinus. Conflicting results reported on nasal NO measurements in various sinonasal diseases are presumed to originate from the variable diffusion of sinus NO into the nose where it is measured. This study presents a novel technique and research method for direct measurement of sinus NO. The authors' original technique of individual, non-destructive catheterization of the sinuses through their natural ostia is developed and refined to allow accurate measurements of NO produced in the sinuses. Our study indicates that reproducible catheterization of the sinuses through their natural ostia can be performed in the clinical research setting under local and topical anesthesia. The model can be used to test the effects of various conditions on nasal and sinus NO production in a variety of disease models and the variables affecting sinonasal gas exchange can be differentially studied. Volunteer healthy adult human subjects without nasal allergies are used. An endoscopic nasal exam with topical anesthesia followed by in vitro allergy testing is performed to determine eligibility. Sinus computerized tomography (CT) scans are used to delineate anatomic features and to calculate paranasal sinus volumes. Continuous flow sinus air sampling and NO measurement with a chemiluminescence analyzer is obtained through polyethylene tube catheters (PEC) placed endoscopically into an aerated major paranasal sinus. Catheters are introduced through natural ostia under local and topical anesthesia. Nasal and differential sinus NO measurements are performed.

Nasal nitric oxide in a random sample of adults and its relationship to sensitization, cat allergen, rhinitis, and ambient nitric oxide

BACKGROUND

There is conflicting evidence whether nasal nitric oxide (NO) is associated with current rhinitis and with other possible predictors. Most studies have been performed in clinical cohorts and there is a lack of studies based on a general population sample. The aim of the present study was to investigate predictors for levels of nasal nitric oxide (NO) in a general population.

METHODS

The population consisted of 357 subjects from Gothenburg participating in the follow-up of the European Respiratory Health Survey in 1999-2001. All subjects completed an extensive respiratory questionnaire. Nasal NO was measured from one nostril at a time with a sampling rate of 50 mL/s for 16 seconds and the nasal NO concentration was determined as the mean value within the plateau phase. Mattress dust samples were collected for cats and mites in a subsample of subjects. Ambient and exhaled NO was also measured. The predictors for nasal NO were analyzed in multiple linear regression models.

RESULTS

There was no relation between the levels of nasal NO and reporting current rhinitis. Nasal NO was significantly increased among those with high levels of IgE against cats and current smokers had significantly lower nasal NO. There was also a positive association between ambient NO and nasal NO. There were no significant associations between nasal NO and sex, age, or height, or between nasal NO and measured levels of cat antigen.

CONCLUSION

In this general population sample we found no relation between current rhinitis and nasal NO levels. There was a clear association between sensitization to cat and nasal NO, but there was no relation to current exposure to cat allergen. Our data support that nasal NO has a limited value in monitoring upper airway inflammation.

Nasal nitric oxide and nasal eosinophils decrease with levocetirizine in subjects with perennial allergic rhinitis

BACKGROUND

Allergic rhinitis is commonly treated with antihistamines. Monitoring improvement of airway inflammation noninvasively using nasal nitric oxide (nNO) would be clinically useful. To determine the anti-inflammatory effect of oral levocetirizine dihydrochloride (LC), we measured nNO and nasal eosinophils (nEos) in perennial allergic rhinitis (PAR) subjects.

METHODS

A randomized double-blind placebo-controlled crossover design was used. Inclusion criteria consisted of subjects having a PAR history, exam and diary scores consistent with active symptoms, and positive skin testing. Subjects taking allergy medications 1 month before the study were not enrolled. After consenting, 31 subjects (24 female subjects; mean age, 29 years) were randomized to either oral LC (5 mg) or matching placebo for 2 weeks. After 2 week washout, subjects started the other 2-week treatment. At each visit, nNO was measured by aspiration at each nare using a nasal kit from NIOX (Aerocrine, Sweden) in parts per billion; nEos was collected from nasal smears and measured by microscopy using the scoring system (0-4+) and symptoms were self-reported using the allergic Rhinitis Quality of Life Questionnaire (RQLQ). Daily allergy symptom scores (total symptom score [TSS] 4) were collected at each visit.

RESULTS

During LC, mean baseline nNO was 807 ± 317 parts per billion (ppb; left) and 831 ± 332 ppb (right) and decreased significantly to 688 ± 266 ppb and 702 ± 286 ppb, respectively (p < 0.05). No significance was found during placebo treatment (778 ± 270 ppb, 808 ± 299 ppb to 802 ± 271 ppb, 813 ± 273 ppb). The mean nNO change was also significant compared with placebo (-125 ppb versus +14 ppb; p < 0.05). There was a significant decrease in nEos with LC compared with placebo (3.1-2.5 versus 2.9-2.6; p < 0.05). RQLQ scores were significantly improved with LC only. In TSS-4 scoring, a trend toward improvement during LC and significant worsening during placebo was found. Baseline nNO predicted changes in nasal eosinophils (nEos) and RQLQ.

CONCLUSION

We showed that oral LC therapy decreased objective markers of rhinitis inflammation, nNO and nEos, in patients with PAR. Improvement in symptom scoring was also found with LC treatment.

Nasal nitric oxide and sinonasal disease: a systematic review of published evidence

OBJECTIVE

To critically and systematically review the data available on the sinonasal application of nasal nitric oxide measurement, particularly its use as a diagnostic, prognostic, or treatment effect indicator.

DATA SOURCES

EMBASE 1980 to February 10, 2010; Medline 1950 to February 10, 2010; Cochrane Collaboration database; NHS Evidence Health Information Resources database. Review Methods. The databases were searched using a search strategy designed to include manuscripts relevant both to nitric oxide measurement and sinus or nasal problems. A title search was carried out on these manuscripts to select those relevant to clinical or basic science aspects of nitric oxide measurement. A subsequent abstract search selected those manuscripts concerning the application of nitric oxide measurement to sinonasal problems. The manuscripts selected were subject to a full-text review to extract data sets of nasal nitric oxide readings for different patient groups.

RESULTS

Initially, 1088 manuscripts were selected. A title search found 335 manuscripts of basic scientific or clinical interest. An abstract search found 35 manuscripts directly relating to nitric oxide measurement in sinonasal disease. Full-text analysis produced 20 studies with extractable data on nasal nitric oxide levels in clearly defined patient groups. Studies did not show sufficient homogeneity to enable substantial meta-analysis of aggregated data.

CONCLUSION

Current evidence shows that nasal nitric oxide is not a clinically useful measure for sinonasal disease. Although there is some evidence that sinus surgery is associated with lowered nasal nitric oxide levels, there is no evidence that this is associated with deterioration in sinus health.

Nasal nitric oxide in children with adenoidal hypertrophy: a preliminary study

OBJECTIVE

Nasal nitric oxide, a mediator involved in upper airway inflammation, is impaired in children with allergic rhinitis and rhinosinusitis. Normal values are 200-450 parts per billion, but no data are available concerning its levels in children with adenoidal obstruction, predisposing to chronic nasosinusal inflammation. This study aimed to: (1) measure nasal nitric oxide levels in non-allergic children with adenoidal hypertrophy and (2) assess its possible relationship with the degree of adenoidal hypertrophy and other variable (gender, age, body max index, passive smoking exposure, recurrent acute otitis media, recurrent respiratory infections, and hypertrophy of nasal turbinates).

METHODS

Eighty-one children with suspected adenoidal hypertrophy underwent nasal fibroendoscopy to assess the degree of adenoidal hypertrophy, and nasal nitric oxide on-line measurements by means of a dedicated chemiluminescence analyser.

RESULTS

Nasal nitric oxide was successfully measured in 35 patients, most of whom had levels >450 parts per billion; the values were significantly higher (p=0.031) in children with non-obstructive adenoids. There was no significant correlation with any other variable.

CONCLUSIONS

Preliminary data show above-normal nasal nitric oxide levels in children with adenoidal hypertrophy, especially those with non-obstructive adenoids. This suggests nitric oxide involvement in recurrent nasopharyngeal inflammation due to adenoidal hypertrophy.

Measurement of nasal nitric oxide: evaluation of six different sampling methods

BACKGROUND

Specific guidelines are developed for the measurement of bronchial FE(NO), however, nasal nitric oxide (nNO) measurement is not standardised yet, resulting in divergent nNO values. This study compares six different sampling methods for nNO as described in the literature, to analyse their outcome and short term and long term reproducibility.

DESIGN

nNO concentrations were measured in 38 healthy subjects. Each subject performed nNO measurements during tidal breathing (nNO-TB), single breath quiet exhalations (nNO-QE), QE with oral exhalation against a resistance (nNO-QE + R), breath holding (nNO-BH) and during single-breath humming exhalations at 128 and 440 Hz (nNO-HE(128) and nNO-HE(440), respectively). To assess short term and long term reproducibility all manoeuvres were repeated after one and 24 h.

RESULTS

Lowest values were found during quiet exhalation (mean nNO-QE was 364 p.p.b., SEM 27). Methods in which there is turbulence of nasal flow (as in TB, HE(128) and HE(440)) result in higher nNO levels. Highest values were found in methods with decreased nasal flow [when there is no nasal flow as in BH or when the velum is closed as in QE + R: mean nNO 763 p.p.b. (SEM 61)]. NNO during humming at 440 Hz was significantly higher than at 128 Hz (P < 0.01). The within-subject coefficient of variation of repeated measurements was lowest during humming and breath holding, 3.4 and 3.8%, respectively. Concerning short term and long term reproducibility, best agreement is reached with humming and second best with breath holding.

CONCLUSIONS

Different methods result in different levels and reproducibility of nNO. In regard to this, methods of humming and breath holding are recommended for standardised measurement of nasal NO.

A methodology for measurements of nasal nitric oxide in children under 5 yr

Measurements of nasal nitric oxide (nNO) may give insight into respiratory conditions in children aged under 5 yr but no methodology has been described for this age-group. The present study aimed to establish the methodology and reproducibility for measuring nNO during tidal breathing in young children and to relate nNO to allergic conditions. Children and siblings aged under 5 yr attending hospital clinics were enrolled. On-line nNO measurements were obtained during tidal breathing using a chemiluminescence analyser. To establish our methodology, nNO was measured over 3, 5 or 10 s NO plateaus and nNO was also measured from left and right nostrils. nNO was then compared between children with and without allergic conditions. The reproducibility of nNO measurements over 24 h was studied in a separate group of children. Eighty-three children participated in the methodological part of the study and nNO was successfully measured in 57 (69%), mean (s.d.) age 3.4 (1.1) years, 14 with allergic conditions. Neither NO plateau duration nor choice of nostril influenced nNO values. The mean (s.d.) nNO for non-atopic children was 208 (103) parts per billion (ppb) and for atopic children was 284 (122), p = 0.032. Nasal NO values were not related to ambient NO, gender and passive smoke exposure; there was a non-significant trend for nNO to be positively related to age. Nasal NO measurements were reproducible in the 21 children tested, mean difference 9.6 ppb (limits of agreement-127, 146). We report a methodology for nNO measurement in young children. Further work is now required to establish the clinical utility of nNO in this age-group.