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

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.

Use of computational fluid dynamics (CFD) to model observed nasal nitric oxide levels in human subjects

BACKGROUND

Upper airway nitric oxide (NO) is physiologically important in airway regulation and defense, and nasal NO (nNO) levels typically exceed those in exhaled breath (fractional exhaled NO [FeNO]). Elevated concentrations of NO sampled from the nose, in turn, reflect even higher concentrations in the paranasal sinuses, suggesting a "reservoir" role for the latter. However, the dynamics of NO flux within the sinonasal compartment are poorly understood.

METHODS

Data from 10 human subjects who had previously undergone both real-time nNO sampling and computed tomography (CT) scanning of the sinuses were analyzed using computational fluid dynamics (CFD) methods. Modeled and observed nNO values during the initial 2-s transient ("spike") during nasal exhalation were then compared.

RESULTS

Examining the initial 2-s transient spike for each subject (as well as the pooled group), there was a statistically significant correlation between modeled and observed nNO levels, with r values ranging from 0.43 to 0.89 (p values ranging from <0.05 to <0.0001). Model performance varied between subjects, with weaker correlations evident in those with high background (FeNO) levels. In addition, the CFD simulation suggests that ethmoid sinuses (>60%) and diffusion process (>54%) contributed most to total nasal NO emissions.

CONCLUSION

Analysis of this dataset confirms that CFD is a valuable modeling tool for nNO dynamics, and highlights the importance of the ethmoid sinuses, as well as the role of diffusion as an initiating step in sinonasal NO flux. Future model iterations may apply more generally if baseline FeNO is taken into account.

Computational modeling of nasal nitric oxide flux from the paranasal sinuses: Validation against human experiment

BACKGROUND

Nitric oxide (NO) is important in respiratory physiology and airway defense. Although the paranasal sinuses are the major source of nasal NO, transport dynamics between the sinuses and nasal cavities are poorly understood.

METHODS

Exhaled nasal NO tracings were measured in two non-asthmatic subjects (one with allergic rhinitis, one without) using NO analyzer connected via face mask. We subsequently performed computational fluid dynamics NO emission simulations based on individual CT scans and compared to the experimental data.

RESULTS

Simulated exhaled NO tracings match well with experimental data (r > 0.84, p < 0.01) for both subjects, with measured peaks reaching 319.6 ppb in one subject (allergic-rhinitis), and 196.9 ppb in the other. The CFD simulation accurately captured the peak differences, even though the initial sinus NO concentration for both cases was set to the same 9000 ppb based on literature value. Further, the CFD simulation suggests that ethmoid sinuses contributed the most (>67%, other sinuses combined <33%) to total nasal NO emission in both cases and that diffusion contributes more than convective transport. By turning off diffusion (setting NO diffusivity to ~0), the NO emission peaks for both cases were reduced by >70%.

CONCLUSION

Historically, nasal NO emissions were thought to be contributed mostly by the maxillary sinuses (the largest sinuses) and active air movement (convection). Here, we showed that the ethmoid sinuses and diffusive transport dominate the process. These findings may have a substantial impact on our view of nasal NO emission mechanisms and sinus physiopathology in general.

The Functional Diversity of Nitric Oxide Synthase Isoforms in Human Nose and Paranasal Sinuses: Contrasting Pathophysiological Aspects in Nasal Allergy and Chronic Rhinosinusitis

The human paranasal sinuses are the major source of intrinsic nitric oxide (NO) production in the human airway. NO plays several roles in the maintenance of physiological homeostasis and the regulation of airway inflammation through the expression of three NO synthase (NOS) isoforms. Measuring NO levels can contribute to the diagnosis and assessment of allergic rhinitis (AR) and chronic rhinosinusitis (CRS). In symptomatic AR patients, pro-inflammatory cytokines upregulate the expression of inducible NOS (iNOS) in the inferior turbinate. Excessive amounts of NO cause oxidative damage to cellular components, leading to the deposition of cytotoxic substances. CRS phenotype and endotype classifications have provided insights into modern treatment strategies. Analyses of the production of sinus NO and its metabolites revealed pathobiological diversity that can be exploited for useful biomarkers. Measuring nasal NO based on different NOS activities is a potent tool for specific interventions targeting molecular pathways underlying CRS endotype-specific inflammation. We provide a comprehensive review of the functional diversity of NOS isoforms in the human sinonasal system in relation to these two major nasal disorders' pathologies. The regulatory mechanisms of NOS expression associated with the substrate bioavailability indicate the involvement of both type 1 and type 2 immune responses.

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.

Predictive and Diagnostic Value of Fractional Exhaled Nitric Oxide in Patients with Chronic Rhinosinusitis

Background

Fractional exhaled nitric oxide (FeNO) participates in the local defense of the upper respiratory tract. Abnormal FeNO level is directly related to the occurrence of nasal diseases. However, the clinical value of FeNO in the upper airway is limited, which greatly impedes the diagnosis and treatment of nasal diseases. Here, we assessed the level of FeNO and evaluated the diagnostic accuracy of FeNO for chronic rhinosinusitis.

Material/Methods

We enrolled 35 patients with confirmed nasal inflammation and 30 healthy subjects from December 2016 and June 2017. The FeNO level was measured using a fractional exhaled nitric oxide detector. The level of FeNO in patients with different clinicopathological factors was compared. The diagnostic potential of FeNO for chronic rhinosinusitis was evaluated by receiver operating characteristic (ROC) curve analysis.

Results

FeNO level was significantly lower in patients with nasal inflammation than in healthy subjects (P<0.05). For nasal inflammation diagnosis, FeNO had the highest area under the curve (AUC) at 0.760, with a sensitivity of 93.30% and a specificity of 68.60%. FeNO level was significantly downregulated in chronic rhinosinusitis patients relative to chronic rhinitis patients (P<0.05). FeNO had a good ability to discriminate between chronic rhinosinusitis patients and chronic rhinitis patients, with higher AUC, sensitivity, and specificity of 0.760, 93.30%, and 68.60%, respectively. However, FeNO levels were not significantly different between different histological types of chronic rhinosinusitis (P>0.05).

Conclusions

Our results show that FeNO is a useful marker for discriminating chronic rhinosinusitis, and has potential to provide valuable information in the early diagnosis of chronic rhinosinusitis.

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.

Oxidative stress and nasal polyposis: does it affect the severity of the disease?

BACKGROUND

Nasal polyposis (NP) is a chronic inflammatory disease and the waste products of this inflammation are reactive oxygen species composed of free radicals. Changes in oxidative status have already been revealed in NP. The aim of this study was to investigate the effect of oxidative status to the severity of the disease and the quality of life.

METHODS

The study group included 24 patients with NP and 20 controls. The Turkish version of the Rhinosinusitis Disability Index, visual analog scale (VAS), polyp stage, computed tomography (CT) score, and the eosinophilic cationic protein (ECP) levels in nasal lavage (NAL) fluid were used to assess the severity of the disease. Malondialdehyde, nitric oxide (NO), and the total antioxidant status (TAS) levels in NAL fluids were measured representing the oxidative stress.

RESULTS

NO values were correlated with nasal congestion (p = 0.031). TAS values were correlated with nasal obstruction (p = 0.039). ECP values showed correlation with all the nasal obstruction (p = 0.003), congestion (p = 0.009), rhinorrhea (p = 0.009), and VAS scores (p = 0.039).

CONCLUSION

In NP, ECP levels detected in NAL fluid were significantly high and were correlated with the severity of the disease. Moreover, the severity of oxidative stress, in the forms of TAS and NO, is significantly correlated with the severity of the nasal obstruction and congestion, respectively.

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.

Thirty minute-exposure to aged cigarette smoke increases nasal congestion in nonsmokers

The aim of this study was to assess the effects of short exposures to experimentally aged cigarette smoke on the nose and upper airways. This crossover study compared the effects of 30-min exposures to (1) experimentally aged cigarette smoke at 1 mg/m³ particulate matter (PM)/14 ppm carbon monoxide (CO) and (2) conditioned filtered air on urinary metabolites of nicotine and tobacco-specific nitrosamines. Subjective nasal symptoms were assessed by questionnaire, objective nasal congestion was assessed by anterior rhinomanometry and nasal nitric oxide (NO) concentrations were determined. Experimentally aged cigarette smoke is a validated model for secondhand smoke (SHS). Twenty-six healthy nonsmokers (10 normal, 7 atopic/nonrhinitic, 7 atopic rhinitic, 2 nonatopic/rhinitic) were studied. A 30-min exposure to SHS increased nasal resistance in healthy nonsmokers. The rise in nasal resistance was most pronounced in rhinitic subjects. Significant increases were not noted when atopic subjects were considered independent of rhinitis status. Secondhand smoke exposure also elevated subjective nasal symptoms and urinary concentrations of metabolites of nicotine (cotinine and trans-3´-hydroxycotinine) and tobacco-specific nitrosamines [(4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL)] in all subgroups of subjects. Exposure-related, subjective nasal symptoms were significantly higher in rhinitic than in normal subjects. Significant changes in nasal NO concentrations were not detected. Data indicate a 30-min exposure to secondhand smoke at 1 mg/m³ PM increases subjective upper respiratory symptoms, increases urinary cotinine and NNAL, and produces objective nasal airflow obstruction in human subjects.