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

Clinical Applications of Nasal Nitric Oxide in Allergic Rhinitis: A Review of the Literature

Allergic rhinitis, a common allergic disease affecting a significant number of individuals worldwide, is observed in 25% of children and 40% of adults, with its highest occurrence between the ages of 20 and 40. Its pathogenesis, like other allergic diseases, involves innate and adaptive immune responses, characterized by immunologic hypersensitivity to environmental substances. This response is mediated by type 2 immunity. Within type 2 allergic diseases, certain molecules have been identified as clinical biomarkers that contribute to diagnosis, prognosis, and therapy monitoring. Among these biomarkers, nitric oxide has shown to play a key role in various physiological and pathological processes, including neurotransmission, immunity, inflammation, regulation of mucus and cilia, inhibition of microorganisms, and tumor cell growth. Therefore, measurement of nasal nitric oxide has been proposed as an objective method for monitoring airway obstruction and inflammation in different settings (community, hospital, rehabilitation) and in various clinical conditions, including upper airways diseases of the nose and paranasal sinuses. The purpose of this review is to analyze the potential mechanisms contributing to the production of nasal nitric oxide in allergic rhinitis and other related health issues. Additionally, this review aims to identify potential implications for future research, treatment strategies, and long-term management of symptoms.

Nasal Nitric Oxide as a Biomarker in the Diagnosis and Treatment of Sinonasal Inflammatory Diseases: A Review of the Literature

OBJECTIVE

To critically review the literature on nasal nitric oxide (nNO) and its current clinical and research applicability in the diagnosis and treatment of different sinonasal inflammatory diseases, including acute bacterial rhinosinusitis (ABRS), allergic rhinitis (AR), and chronic rhinosinusitis (CRS).

METHODS

A search of the PubMed database was conducted to include articles on nNO and sinonasal diseases from January 2003 to January 2020. All article titles and abstracts were reviewed to assess their relevance to nNO and ABRS, AR, or CRS. After selection of the manuscripts, full-text reviews were performed to synthesize current understandings of nNO and its applications to the various sinonasal inflammatory diseases.

RESULTS

A total of 79 relevant studies from an initial 559 articles were identified using our focused search and review criteria. nNO has been consistently shown to be decreased in ABRS and CRS, especially in cases with nasal polyps. While AR is associated with elevations in nNO, nNO levels have also been found to be lower in AR cases with higher symptom severity. The obstruction of the paranasal sinuses is speculated to be an important variable in the relationship between nNO and the sinonasal diseases. Treatment of these diseases appears to affect nNO through the reduction of inflammatory disease burden and also mitigation of sinus obstruction.

CONCLUSION

nNO has been of increasing interest to researchers and clinicians over the last decade. The most compelling data for nNO as a clinical tool involve CRS. nNO can be used as a marker of ostiomeatal complex patency. Variations in measurement techniques and technology continue to impede standardized interpretation and implementation of nNO as a biomarker for sinonasal inflammatory diseases.

Nasal nitric oxide flux from the paranasal sinuses

PURPOSE OF REVIEW

Upper airway nitric oxide (NO) is physiologically important in airway regulation and defense, and can be modulated by various airway inflammatory conditions, including allergic rhinitis and chronic rhinosinusitis - with and without polyposis. Paranasal sinuses serve as a NO 'reservoir', with concentrations typically exceeding those measured in lower airway (fractional exhaled NO or FeNO) by a few orders of magnitude. However, the dynamics of NO flux between the paranasal sinuses and main nasal airway, which are critical to respiratory NO emission, are poorly understood.

RECENT FINDINGS

Historically, NO emissions were thought to be contributed mostly by the maxillary sinuses (the largest sinuses) and active air movement (convection). However, recent anatomically-accurate computational modeling studies based on patients' CT scans showed that the ethmoid sinuses and diffusive transport dominate the process.

SUMMARY

These new findings may have a substantial impact on our view of nasal NO emission mechanisms and sinus physiopathology in general.

Efficacy of Pranayama in Preventing COVID-19 in Exposed Healthcare Professionals: A Quasi-Randomized Clinical Trial

Background

The global outbreak of COVID-19 has created a challenging situation, especially for the frontline Health Care Professionals (HCPs), who are routinely exposed and thus are at a higher risk of infection. Pranayama, a component of Yoga, is known to improve immune function and reduce infection. However, no clinical trial on the efficacy of Pranayama in preventing COVID-19 has yet been conducted.

Aim & Objective

This quasi-randomized clinical trial assessed the efficacy of Pranayama in preventing COVID-19 infection in HCPs routinely exposed to COVID-19.

Methodology

The study was conducted at 5 different COVID-19 hospitals, India in year 2020. The inclusion criteria were being an HCP exposed to COVID-19 patients and being negative on antibody tests. 280 HCPs were recruited sequential and assigned to intervention and control groups. Of these, 250 HCPs completed the study. The intervention was twice daily practice, for 28 days, of specially designed Pranayama modules under the online supervision of Yoga instructors. The HCPs in the control group were advised to continue their normal daily routine, but no pranayama sessions. Participants who developed symptoms suggestive of COVID-19 were subjected to Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) or Point of Care Rapid Antigen Test (RAT) for confirmation of the diagnosis. All the participants were tested for antibodies to COVID-19 on 28^th day of the intervention to detect any asymptomatic infection.

Results

The intervention (123) and control (127) groups had comparable demographics and baseline characteristics. At end of 28 days of intervention, nine participants in the control group and one in the intervention group developed COVID-19 (P-value: 0.01, Odds Ratio: 0.107, 95% CI: 0.86; Risk Ratio: 0.11, 95% CI: 0.89).

Conclusion

The intervention of twice daily practice of the Pranayama module for 28 days in HCPs might have made a noteworthy contribution and may have helped in preventing COVID-19 infection.

CTRI Number

CTRI/2020/07/026667.

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.

Fractional Exhaled Nitric Oxide (FENO) in the management of asthma: a position paper of the Italian Respiratory Society (SIP/IRS) and Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC)

Asthma prevalence in Italy is on the rise and is estimated to be over 6% of the general population. The diagnosis of asthma can be challenging and elusive, especially in children and the last two decades has brought evidences that asthma is not a single disease but consists of various phenotypes. Symptoms can be underestimated by the patient or underreported to the clinician and physical signs can be scanty. Usual objective measures, like spirometry, are necessary but sometimes not significant. Despite proper treatment, asthma can be a very severe condition (even leading to death), however new drugs have recently become available which can be very effective in its control. Since asthma is currently thought to be caused by inflammation, a direct measure of the latter can be of paramount importance. For this purpose, the measurement of Fractional Exhaled Nitric Oxide (FE_NO) has been used since the early years of the current century as a non-invasive, easy-to-assess tool useful for diagnosing and managing asthma. This SIP-IRS/SIAAIC Position Paper is a narrative review which summarizes the evidence behind the usefulness of FE_NO in the diagnosis, management and phenotypization of asthma.

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 Nitric Oxide in Chronic Rhinosinusitis and Its Relationship to Patient-Reported Outcome: A Longitudinal Pilot Study

OBJECTIVE

To assess whether nasal nitric oxide (nNO) levels differ between healthy and sick sinuses in chronic rhinosinusitis (CRS). A secondary aim was to assess whether nNO levels change after treatment of CRS and whether there is an association with radiological findings or symptoms.

METHOD

Three groups of 12 participants each were examined: patients with CRS without polyposis (CRS group), patients with symptoms of CRS but radiologically normal sinuses (symptoms-only), and healthy controls. Measurements of nNO were carried out using aspiration method and humming maneuver. All participants completed the Sino-Nasal Outcome Test (SNOT-22). A second nNO measurement was done after treatment in the CRS group (n = 9) and the healthy control group (n = 12).

RESULTS

Nasal NO did not differ between any of the groups with any of the measurement techniques. There was a trend toward lower nNO values in the CRS group compared with the symptoms-only group and healthy controls, but it did not reach statistical significance. The SNOT-22 demonstrated inferior values for the CRS and symptoms-only groups compared with the healthy controls. At follow-up, no statistically significant change was found for the nNO measurements in either group.

CONCLUSION

Irrespective of occluded or open ostiomeatal complexes, no statistically significant differences in nNO were found in CRS compared with healthy controls using aspiration and humming methods. Treatment of CRS improved sinus patency without accompanying a significant change in nNO. This study can therefore not conclude that nNO can be used as a diagnostic tool for CRS without polyposis.

Correlation of Exhaled Nasal Nitric Oxide With Sinus Computed Tomography and Sinonasal Outcome Test Scores: A Cross-sectional Pilot Study

BACKGROUND

Computed tomography (CT) of the paranasal sinuses is the diagnostic reference standard for chronic rhinosinusitis and related inflammatory sinus pathology. Nasal nitric oxide (nNO) levels have been investigated as a diagnostic tool in sinus disease because it decreases with sinus obstruction.

OBJECTIVE

The primary aim of the study was to determine the correlation of passive (baseline) and dynamic (humming) nNO to CT findings of sinus inflammation and to sinonasal symptoms measured by the modified Sinonasal Outcome Test (26 items) (SNOT-26).

METHODS

From June 2015 through January 2016, subjects had baseline and humming nNO levels measured with a chemiluminescence NO analyzer, and each subject underwent CT imaging and completed the SNOT-26 survey. CT images were scored using the Lund-Mackay (LM) system (LM scores >3 indicated sinus inflammation). Correlation was measured by linear and ordinal regression analysis that compared SNOT-26 scores, LM scores, and nNO measurements.

RESULTS

Fourteen subjects were recruited. LM scores had a positive pairwise correlation with total SNOT-26 scores ( R² = .1457; correlation = .3817) and nasal-specific SNOT-26 scores ( R² = .4036; correlation = .6353). Baseline nasal nNO scores had a negative pairwise correlation with LM scores ( R² = .1580; correlation = -.3582), total SNOT-26 scores ( R² = .1515; correlation = -.3893), and nasal-specific SNOT-26 scores ( R² = .0805; correlation = -.4343). Although baseline nNO levels correlated with LM and SNOT-26 scores, humming nNO levels did not show a similar correlation.

CONCLUSION

Baseline passive nNO may be a useful and inexpensive point-of-care screening test for sinonasal opacification.

Lessons From Unilateral Loss of Cilia: Early Nasal Nitric Oxide Gas Mixing and the Role of Sinus Patency in Determining Nasal Nitric Oxide

Nasal nitric oxide (nNO) measurement is a diagnostic test for primary ciliary dyskinesia (PCD). Here, we have shown the development of unilateral PCD-like symptoms associated with low nNO. A 60-year-old man had been previously healthy but developed unilateral, severe pansinusitis. He required surgical drainage of all left sinuses, and biopsies showed loss of the ciliated epithelium. At 4 weeks, he had unilateral (left-sided), profuse, clear rhinorrhea characteristic of PCD, and his surgical ostia were all patent endoscopically. His left-sided nNO was less than the right side by 37 ± 1.2 nL/min; this difference decreased to 18 ± 0.87 nL/min at 5 weeks and was gone by 6 weeks when his symptoms resolved. Measurements of 2- and 10-second measurements, in addition to standard nNO measurements, identified this discordance. We conclude that nNO reflects, in part, the production of NO by the ciliated epithelium, not just in the absence or occlusion of sinuses. Early (nasal/sinus volume) measures may be better for diagnosing PCD in than standard, steady-state assays in certain populations.

Exhaled and nasal nitric oxide in relation to lung function, blood cell counts and disease characteristics in cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) have similar or lower exhaled nitric oxide (FeNO) and lower nasal nitric oxide (nNO) levels than controls. There are divergent results on alveolar NO (Calv_NO) concentrations in relation to CF. There are inconsistent results on correlation between different nitric oxide parameters and lung function and inflammation in CF.

AIM

To compare FeNO, Calv_NO and nNO levels between subjects with CF, asthma and healthy controls and to study whether these parameters are related to lung function, blood cell counts or clinical characteristics in CF patients.

MATERIAL AND METHODS

Measurements of FeNO at multiple exhalation flow rates, nNO and spirometry were done in 38 patients (18 adults) with CF. Blood cell counts and CF clinical characteristics were recorded. Thirty-eight healthy controls and 38 asthma patients, gender- and age-matched, were included as reference groups.

RESULTS

FeNO levels were lower in CF patients (7.2 [4.7-11.2] ppb) than in healthy controls (11.4 [8.3-14.6] ppb) and asthma patients (14.7 [8.7-24.7] ppb) (both p < 0.005). These differences were consistent in adults. No difference in Calv_NO was seen between the groups. nNO levels in CF patients (319 [193-447] ppb) were lower than in healthy controls (797 [664-984] ppb) and asthma patients (780 [619-961] ppb) (both p < 0.001). FeNO positively related to FEV₁ (rho = 0.51, p = 0.001) in CF patients and this was consistent in both adults and children. A negative correlation was found between FeNO and blood neutrophil counts (rho = -0.37, p = 0.03) in CF patients.

CONCLUSION

CF patients have lower FeNO and nNO and similar Calv_NO levels as healthy controls and asthma patients. Lower FeNO related to lower lung function in both adults and children with CF. Furthermore, in CF, lower FeNO also related to higher blood neutrophil counts.

Fractional exhaled nitric oxide-measuring devices: technology update

The measurement of exhaled nitric oxide (NO) has been employed in the diagnosis of specific types of airway inflammation, guiding treatment monitoring by predicting and assessing response to anti-inflammatory therapy and monitoring for compliance and detecting relapse. Various techniques are currently used to analyze exhaled NO concentrations under a range of conditions for both health and disease. These include chemiluminescence and electrochemical sensor devices. The cost effectiveness and ability to achieve adequate flexibility in sensitivity and selectivity of NO measurement for these methods are evaluated alongside the potential for use of laser-based technology. This review explores the technologies involved in the measurement of exhaled NO.

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.

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.

Pilot evaluation of the nasal nitric oxide response to humming as an index of osteomeatal patency

BACKGROUND

Paranasal sinuses are reservoirs for nitric oxide (NO), and humming facilitates nasal diffusion of NO. The nasal NO response to humming has previously been shown to be blunted with chronic sinusitis and nasal polyposis. We hypothesized that the nasal NO response to humming will be proportional to radiographic osteomeatal patency when comparing allergic rhinitis (AR) patients (without chronic sinusitis) with normal controls.

METHODS

Nonsmoking subjects completed questionnaires and skin-prick testing. Subjects underwent sinus CT scanning, followed by exhaled (oral) and nasal NO sampling (with and without humming). Humming-to-quiet (H/Q) nasal NO ratios were calculated. Three-dimensional reconstructions were used to trace the osteomeatal complex (OMC) and measure minimum cross-sectional area. Lund-Mackay scores were also documented.

RESULTS

A total of 33 subjects (22 women; mean age, 35.5 years) completed the study. Seventeen AR patients (5 IAR and 12 PAR) participated, as did 16 nonallergic controls. Among controls, quiet nasal NO levels--corrected for fractional exhaled NO--rose significantly with OMC area and fell significantly with Lund-Mackay scores (p < 0.05). However, we observed no proportionality between H/Q ratio and radiographic OMC patency.

CONCLUSION

Analysis of nasal NO samples taken under quiet conditions from normal controls was consistent with the paranasal sinuses acting as a reservoir of nasal NO and with OMC patency acting as a significant factor in NO diffusion. However, our results did not support a relationship between the nasal NO response to humming and radiographic OMC patency in a sample excluding subjects with severe rhinosinusitis.

Measurement of nasal nitric oxide by hand-held and stationary devices

BACKGROUND

Nasal nitric oxide (nNO) is assessed by nasal aspiration/insufflation via one nostril or by nasal silent exhalation through a facemask and is also measured during humming, a manoeuvre that results in increased nNO in the presence of a patent osteomeatal complex. Humming nNO peak is absent in primary ciliary dyskinesia (PCD) and in cystic fibrosis (CF). Hand-held devices are used successfully for exhaled or nNO analysis. No study compared nNO during silent and humming exhalation using hand-held and stationary analysers.

METHODS

Thirty-eight subjects (14 PCD; 11 CF; 13 healthy individuals) measured nNO with a stationary and a hand-held analyser during silent and humming exhalations.

RESULTS

No difference between nNO obtained from stationary or hand-held analyser during silent and humming exhalation was found (P > 0·05). Patients with PCD exhibited lower silent and humming nNO than CF or controls (P < 0·001). During both silent and humming exhalation, there was a significant correlation between nNO from the two analyzers both in the whole study population and within each group (r ≥ 0·7, P < 0·01). Bland-Altman plots confirmed this agreement. Using the hand-held device during humming, nNO values of 50, 81 and 21 ppb had sensitivity and specificity > 90% for discriminating PCD or CF from healthy subjects, and patients with PCD from patients with CF, respectively.

CONCLUSIONS

The hand-held device is as effective as the stationary analyzer for assessing nNO during silent and humming exhalation. Its wider use might result in an increased number of subjects suspected to have PCD.

Exhaled and nasal nitric oxide in laryngectomized patients

Background

Nitric oxide (NO) shows differing concentrations in lower and upper airways. Patients after total laryngectomy are the only individuals, in whom a complete separation of upper and lower airways is guaranteed. Thus the objective of our study was to assess exhaled and nasal NO in these patients.

Methods

Exhaled bronchial NO (FE_NO) and nasal nitric oxide (nNO) were measured in patients after total laryngectomy (n = 14) and healthy controls (n = 24). To assess lung function we additionally performed spirometry. Co-factors possibly influencing NO, such as smoking, infections, and atopy were excluded.

Results

There was a markedly (p < 0.001) lower FE_NO in patients after total laryngectomy (median (range): 4 (1-22) ppb) compared to healthy controls 21 (9-41) ppb). In contrast, nNO was comparable between groups (1368 versus 1380 in controls) but showed higher variability in subjects after laryngectomy.

Conclusions

Our data suggest that either bronchial NO production in patients who underwent laryngectomy is very low, possibly due to alterations of the mucosa or oxidant production/inflammation, or that substantial contributions to FE_NO arise from the larynx, pharynx and mouth, raising FE_NO despite velum closure. The data fit to those indicating a substantial contribution to FE_NO by the mouth in healthy subjects. The broader range of nNO values found in subjects after laryngectomy may indicate chronic alteration or oligo-symptomatic inflammation of nasal mucosa, as frequently found after total laryngectomy.

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.

Documentation of the nasal nitric oxide response to humming: methods evaluation

RATIONALE

Nitric oxide (NO) is present at higher concentrations in the nasal cavity than in the lower airway, and at even higher concentrations within the paranasal sinuses proper. When the paranasal sinus ostia are patent, acoustic activity produced by vocalization with closed lips (humming) promotes mixing of sinus with nasal gases, producing a further increase in nasal NO. We wished to evaluate procedures for the documentation of the nasal NO response to humming.

MATERIALS AND METHODS

We compared two ATS-recommended sampling methods: 1) active exhalation of lower airway gas (parallel technique) and 2) passive aspiration of nasal gas with closed velopharynx (series technique). Variables controlled for included sampling rate, external resistance (parallel method), humming frequency, humming duration, and intertrial interval. Prior to upper airway sampling, exhaled lower airway NO was determined utilizing ATS-standardized technique.

RESULTS

Ten volunteers (seven males and three females, aged 21-58) with no history of respiratory allergies or sino-nasal disease were studied in a single session each. The parallel technique documented an increase in nasal NO during the humming manoeuvre in all subjects (mean ratio of humming-to-quiet NO, 4.2), whereas the series technique did so in eight of 10 subjects (mean ratio 2.1). Correcting for admixture from the lower airway, the ratio of humming-to-quiet NO was greater with the parallel than series sampling technique (P < 0.05).

CONCLUSIONS

Documentation of the response of nasal NO to humming in subjects without sino-nasal disease was consistently achievable by parallel sampling using commercially available equipment. Specific operational procedures are proposed.

Measurement of nasal nitric oxide

Nasal nitric oxide (nNO) is produced in high quantity in the upper airways. It is thought to be involved in host defence functions and regulation of mucociliary function, and to serve as a biochemical airborne transmitter. The measurement of nNO is easy and non-invasive. It has evolved as a screening test to exclude primary ciliary dyskinesia (PCD) in patients with suggestive symptoms, because nNO is extremely low in this condition. Nasal NO is also altered in other nasal, sinus and pulmonary pathologies, but is without diagnostic value outside of PCD.

Nasal nitric oxide in cystic fibrosis with and without humming

BACKGROUND

Nasal nitric oxide (nNO) values are reduced in patients with cystic fibrosis (CF). Humming during nNO measurement increases nNO values in healthy subjects. Nasal NO is reduced in patients with CF, sinus disease or nasal polyps. Humming nNO values have not been reported in CF patients yet. Our aim was to explore humming nNO values in CF patients and assess whether nNO during humming is a better discriminator than silent nNO measurements in this patient group.

MATERIALS AND METHODS

In a cross sectional study we measured nNO concentrations in healthy controls (HC) and in CF patients (n = 23 and 31, respectively). The participants held their breath for 10 s while air was passively extracted from one nostril with 700 mL min(-1) for direct NO measurements (NIOX chemiluminescence analyser). Subsequently nNO was measured during humming with the mouth closed for 10 s.

RESULTS

Mean nNO in parts per billion (p.p.b.) (SD) during breath hold was 499 (164) and 240 (139), respectively. The median nNO peak (p.p.b., minimum-maximum) during humming was 1500 (425-4100) for HC and 120 (23-500) for CF. There was a highly significant difference between nNO both with and without humming between CF and HC (P < 0.01). The sensitivity and specificity of nNO for detecting CF were better with humming.

CONCLUSION

Nasal NO concentrations with and without humming are significantly decreased in CF. Humming nNO is an excellent discriminator between HC and CF and performs better than silent nNO.

Sounding airflow enhances aerosol delivery into the paranasal sinuses

BACKGROUND

The use of aerosol therapy is commonly suggested in the treatment of paranasal disorders but it is difficult to achieve an effective penetration of drugs into the sinuses. The authors have recently shown that an oscillating airflow produced by phonation (nasal humming) causes a large increase in the gas exchange between the nose and the paranasal sinuses. This is reflected by a high peak in nasally exhaled nitric oxide (NO) levels because NO accumulated in the sinuses is rapidly washed-out via the sinus ostia.

OBJECTIVE

This study was designed to test whether the increase in sinus gas exchange caused by an oscillating airflow could be used to enhance penetration of a drug into the sinuses.

MATERIALS AND METHODS

In six healthy subjects a nitric oxide-synthase inhibitor L-NAME was administrated into the nostrils by a jet nebulizer connected to a duck call, which could be modified to generate either a sounding airflow or a non-sounding airflow. The degree of L-NAME penetration into the sinuses was judged from the reduction in nasal NO during humming exhalations. Sinus drug deposition was also studied in a model of the nose and sinus.

RESULTS

In humans the delivery of L-NAME with the non-sounding airflow had no effect on the NO levels achieved during humming, whereas L-NAME administration with sound caused a significant 22-35% reduction in nasal NO. In the model the aerosol delivery with the sounding airflow caused a fourfold increase in sinus drug deposition as compared with an aerosol without sound.

CONCLUSION

A sounding airflow increases the delivery of an aerosolized drug into the paranasal sinuses.

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.

A comparison between nitric oxide output in the nose and sinuses: A pilot study in one volunteer

From a study of nitric oxide (NO) output in the nose and sinuses it seems that: (i) the results obtained regarding the regulation of NO output in the nose do not necessarily apply to the sinuses; (ii) the results obtained for one group of sinuses may not apply to another; and (iii) NO output in the sinuses does not behave as one would expect if it serves to protect against infection.A pilot study was undertaken in one subject to determine whether the control of NO output in the nose differs from that in the sinuses.NO output was measured by aspirating different gaseous concentrations of oxygen (and/or carbon dioxide) through the nasal airways or punctured maxillary and frontal sinuses before and after i.v. administration of L-arginine (20 mg/kg). In the absence of gaseous oxygen in the nose or maxillary antrum, the effect of L-arginine on NO output was the same as that in the presence of oxygen. In the frontal sinus, the effect of L-arginine on NO output was blocked by the absence of gaseous oxygen. NO output in the nose and frontal sinus showed similar changes after either i.v. administration of L-arginine or removal of oxygen from the air. NO output in the maxillary antrum was virtually unaffected by either procedure. NO output in the nose was largely unaffected by the gaseous carbon dioxide content but that in the frontal and maxillary sinuses was profoundly inhibited by it. In both sinuses, suppression of NO output by carbon dioxide was countered by oxygen. Alterations in the oxygen or carbon dioxide content of the maxillary antrum did not alter NO output in the frontal sinus, or vice versa. After i.v. infusion of L-arginine, nasal NO output remained elevated for >1 h.

Silent and humming nasal NO measurements in adults aged 18-70 years

BACKGROUND

The concentration of nitric oxide (NO) measured from the nose is much higher than in the lower airways and increases during humming. We assessed nasal NO (nNO) normal values during breath hold and during humming in healthy adults.

MATERIALS AND METHODS

Nasal NO concentrations were measured in healthy adults (ages 18-70). They held their breath for 10 s and thereafter hummed as loud as possible with their mouths closed also for 10 s. During breath hold, air was passively extracted from one nostril with 700 mL min(-1). The average NO concentration at the plateau after 7-10 s was recorded and the mean of three consecutive measurements was calculated. During humming, air was extracted with 1200 mL min(-1), the peak NO values were recorded.

RESULTS

One hundred healthy adults participated (37 men). The nNO concentrations during breath hold were distributed normally (mean: 455 parts per billion (p.p.b.), SD 147). A random subgroup of 40 out of the 100 subjects (15 men) performed nNO measurement during humming. The median peak NO value was 1019 p.p.b. (SD 561) at the first, and 837 p.p.b. (SD 408) at the second measurement. There was a significant difference between the peak NO values of first and second humming.

CONCLUSION

We present normal values for nNO in adults, which can be used to assess the value of nNO in respiratory illnesses. The peak nNO values during humming are variable, and their clinical relevance remains to be shown.