Nasal flow, volumes, and minimal cross sectional areas in asthmatics

State of the art: Alternative overlap syndrome-asthma and obstructive sleep apnea

In the general population, Bronchial Asthma (BA) and Obstructive Sleep Apnea (OSA) are among the most prevalent chronic respiratory disorders. Significant epidemiologic connections and complex pathogenetic pathways link these disorders via complex interactions at genetic, epigenetic, and environmental levels. The coexistence of BA and OSA in an individual likely represents a distinct syndrome, that is, a collection of clinical manifestations attributable to several mechanisms and pathobiological signatures. To avoid terminological confusion, this association has been named alternative overlap syndrome (vs overlap syndrome represented by the chronic obstructive pulmonary disease-OSA association). This comprehensive review summarizes the complex, often bidirectional links between the constituents of the alternative overlap syndrome. Cross-sectional, population, or clinic-based studies are unlikely to elucidate causality or directionality in these relationships. Even longitudinal epidemiological evaluations in BA cohorts developing over time OSA, or OSA cohorts developing BA during follow-up cannot exclude time factors or causal influence of other known or unknown mediators. As such, a lot of pathophysiological interactions described here have suggestive evidence, biological plausibility, potential or actual directionality. By showcasing existing evidence and current knowledge gaps, the hope is that deliberate, focused, and collaborative efforts in the near-future will be geared toward opportunities to shine light on the unknowns and accelerate discovery in this field of health, clinical care, education, research, and scholarly endeavors.

Revisiting Asthma Obstructive Sleep Apnea Overlap: Current Knowledge and Future Needs

Asthma and obstructive sleep apnea are highly prevalent conditions with a high cost burden. In addition to shared risk factors, existing data suggest a bidirectional relationship between asthma and OSA, where each condition can impact the other. Patients with asthma often complain of sleep fragmentation, nocturnal asthma symptoms, daytime sleepiness, and snoring. The prevalence of OSA increases with asthma severity, as evidenced by multiple large studies. Asthma may lower the threshold for arousal in OSA, resulting in the hypopnea with arousal phenotype. Epidemiologic studies in adults have shown that OSA is associated with worse asthma severity, increased frequency of exacerbation, and poor quality of life. The current literature assessing the relationship among OSA, asthma, and CPAP therapy is heavily dependent on observational studies. There is a need for randomized controlled trials to minimize the interference of confounding shared risk factors.

The nose has it: Opportunities and challenges for intranasal drug administration for neurologic conditions including seizure clusters

Nasal administration of treatments for neurologic conditions, including rescue therapies to treat seizure clusters among people with epilepsy, represents a meaningful advance in patient care. Nasal anatomy and physiology underpin the multiple advantages of nasal administration but also present challenges that must be addressed in any successful nasal formulation. Nasal cavity anatomy is complex, with a modest surface area for absorption that limits the dose volume of an intranasal formulation. The mucociliary clearance mechanism and natural barriers of the nasal epithelia must be overcome for adequate absorption. An extensive vasculature and the presence of olfactory nerves in the nasal cavity enable both systemic and direct-to-brain delivery of drugs targeting the central nervous system. Two intranasal benzodiazepine rescue therapies have been approved by the US Food and Drug Administration for seizure-cluster treatment, in addition to the traditional rectal formulation. Nasal sprays are easy to use and offer the potential for quick and consistent bioavailability. This review aims to increase the clinician's understanding of nasal anatomy and physiology and of the formulation of intranasal rescue therapies and to facilitate patient education and incorporate intranasal rescue therapies for seizure clusters (also known as acute repetitive seizures) into their seizure action plans.

Association Between Mouth Breathing and Asthma: a Systematic Review and Meta-analysis

PURPOSE OF REVIEW

This systematic review and meta-analysis evaluated the association between asthma and mouth breathing. We performed a systematic search in the PubMed, SCOPUS, Lilacs, Web of Science, Google Scholar and OpenThesis databases.

RECENT FINDINGS

Asthma is defined as a heterogeneous disease characterized by variable symptoms of wheezing, shortness of breath, chest oppression and/or cough, and limitation of expiratory airflow. Although several studies have examined the association between asthma and mouth breathing, there are no systematic reviews or meta-analyses that synthesize the available bodies of evidence. We used the odds ratio as a measure of the association between asthma and mouth breathing. Summary estimates were calculated using random-effects models, and the risk of bias was estimated using the Newcastle-Ottawa Scale for case-control studies and the National Institutes of Health tool for cross-sectional studies. Nine studies were included in the present systematic review. Data from 12,147 subjects were analyzed, of which 2083 were children and adolescents and 10,064 were adults. We found an association between mouth breathing and asthma in children and adolescents (OR 2.46, 95% CI 1.78-3.39) and in adults (OR 4.60, 95% CI 1.49-14.20). However, limitations were found in the methodological description of the included studies, as well as high heterogeneity among studies evaluating adult populations. This meta-analysis showed an association between mouth breathing and asthma in children, adolescents and adults, but the results should be interpreted with caution. Further studies with standardized criteria for the investigation of mouth breathing are needed.

Nasal Peak Inspiratory Flow in Healthy and Obstructed Patients: Systematic Review and Meta-Analysis

OBJECTIVES

Nasal peak inspiratory flow (NPIF) is a practical and affordable tool that measures maximum inspiratory flow rate through both nostrils. Although NPIF values for healthy controls and patients appear to differ considerably, a generally expected value for populations with and without nasal obstruction has yet to be established. The aim of this systematic review and meta-analysis was to determine the mean NPIF value in populations with and without nasal obstruction.

METHODS

Medline (1946-) and Embase (1947-) were searched until July 1, 2017. A search strategy was used to identify studies that reported NPIF values for defined healthy or disease states. All studies providing original data were included. The study population was defined as having either normal nasal breathing or nasal obstruction. A meta-analysis of the mean data was presented in forest plots, and data were presented as mean (95% confidence interval [CI]).

RESULTS

The search yielded 1,526 studies, of which 29 were included. The included studies involved 1,634 subjects with normal nasal breathing and 817 subjects with nasal obstruction. The mean NPIF value for populations with normal nasal breathing was 138.4 (95% CI: 127.9-148.8) L/min. The mean value for populations with nasal obstruction was 97.5 (95% CI: 86.1-108.8) L/min.

CONCLUSIONS

Current evidence confirms a difference between mean NPIF values of populations with and without nasal obstruction. The mean value of subjects with no nasal obstruction is 138.4 L/min, and the mean value of nasally obstructed populations is 97.5 L/min. Prospective studies adopting a standardized procedure are required to further assess normative NPIF values. Laryngoscope, 131:260-267, 2021.

The complexities of nasal airflow: theory and practice

The objective of this study was to investigate the effects of nasal valve area, valve stiffness, and turbinate region cross-sectional area on airflow rate, nasal resistance, flow limitation, and inspiratory "hysteresis" by the use of a mathematical model of nasal airflow. The model of O'Neill and Tolley (Clin Otolaryngol Allied Sci 13: 273-277, 1988) describing the effects of valve area and stiffness on the nasal pressure-flow relationship was improved by the incorporation of additional terms involving 1) airflow through the turbinate region, 2) the dependence of the flow coefficients for the valve and turbinate region on the Reynolds number, and 3) effects of unsteady flow. The model was found to provide a good fit for normal values for nasal resistance and for pressure-flow curves reported in the literature for both congested and decongested states. Also, by showing the relative contribution of the nasal valve and turbinate region to nasal resistance, the model sheds light in explaining the generally poor correlation between nasal resistance measurements and the results from acoustic rhinometry. Furthermore, by proposing different flow conditions for the acceleration and deceleration phases of inspiration, the model produces an inspiratory loop (commonly referred to as hysteresis) consistent with those reported in the literature. With simulation of nasal flaring, the magnitude of the loop, the nasal resistance, and flow limitation all show change similar to that observed in the experimental results.NEW & NOTEWORTHY The present model provides considerable insight into some difficult conundrums in both clinical and technical aspects of nasal airflow. Also, the description of nasal airflow mechanics based on the Hagen-Poiseuille equation and Reynolds laminar-turbulent transition in long straight tubes, which has figured prominently in medical textbooks and journal articles for many years, is shown to be seriously in error at a fundamental level.

Improvement in minimal cross-sectional area and nasal-cavity volume occurs in different areas after septoplasty and radiofrequency therapy of inferior turbinates

PURPOSE

Septoplasty and radiofrequency therapy for inferior turbinate hypertrophy (RFIT) are common techniques used to improve nasal patency. Our aim was to compare nasal geometry and function using acoustic rhinometry and peak nasal inspiratory flow (PNIF) in three patients groups undergoing surgery for nasal obstruction, and to investigate if the improvement in minimal cross-sectional area (MCA) and nasal-cavity volume (NCV) occurred in different cavity areas in the groups. Finally, we evaluated the correlation between the objective measurements and the patients' assessment of nasal obstruction (SNO).

METHODS

This prospective, observational study investigated 148 patients pre-operatively and 6 months post-operatively. Fifty patients underwent septoplasty (group 1), 51 underwent septoplasty combined with RFIT (group 2), and 47 underwent RFIT alone (group 3). The MCA and NCV were measured at two distances (MCA/NCV_0-3.0 and MCA/NCV_3-5.2), in addition to measuring PNIF and SNO.

RESULTS

Pre-operatively, groups 1 and 2 had narrower MCA_0-3.0 on one side than group 3 (0.31 ± 0.14 and 0.31 ± 0.14) versus (0.40 ± 0.16) cm². Post-operatively, total MCA_0-3.0 and MCA/NCV_3-5.2 increased in group 1. In group 2, MCA/NCV_0-3.0 at the narrow side and total MCA/NCV_3-5.2 increased, while total MCA/NCV_3-5.2 increased in group 3. PNIF improved from 106 ± 49 to 150 ± 57 l/min post-operatively. We found a correlation between increased MCA and NCV and less SNO in the septoplasty group (p < 0.01).

CONCLUSION

Surgery produced an improvement in MCA and NCV in all groups. The improvement occurred in different areas of the nasal cavity in the patient groups. Both anterior and posterior areas increased in the septoplasty groups, while only the posterior area increased in the RFIT group. PNIF improved in all three patient groups, indicating that surgery produced an improvement in nasal patency.

Sinonasal Characteristics in Patients with Obstructive Sleep Apnea Compared to Healthy Controls

Background. The difference in nasal obstruction between OSA patients and healthy individuals is not adequately documented. Our aim was to describe the sinonasal quality of life and nasal function in OSA patients and healthy controls using the sinonasal outcome test-20 (SNOT-20), nasal obstruction visual analog scale (NO-VAS), and peak nasal inspiratory flow (PNIF). Methodology and Principal. Ninety-three OSA patients and 92 controls were included in a case-control study from 2010 to 2015. Results. Mean SNOT-20 score in the OSA group was 1.69 (SD 0.84) compared to 0.55 (SD 0.69) in controls (p < 0.001, 95% CI [0.9, 1.4]). The mean NO-VAS score was 41.3 (SD 12.8) and 14.7 (SD 14.4) in the OSA group and controls, respectively, (p < 0.001, 95% CI [22.7, 30.6]). PNIF measured 105 litres/minute in the OSA group and 117 litres/minute in controls (p < 0.01, 95% CI [−21.8, −3.71]). There was a positive correlation between subjective nasal obstruction and change in PNIF after decongestion in the control group alone. Conclusions. OSA patients have a reduced sinonasal QoL and lower peak nasal inspiratory flow compared to controls. Treatment of nasal obstruction in OSA patients should be made a priority along with treatment of the ailment itself.

Nasal septal deviation with obstructive symptoms: Association found with asthma but not with other general health problems

BACKGROUND

Nasal septal deviation (NSD) is a very common deformity. Because it may induce chronic upper airway obstruction in the nose, clinicians encounter some patients who have concerns about whether this can be a risk factor for general health. However, the influence of NSD on general health has rarely been studied.

OBJECTIVE

To determine associations between NSD, especially NSD with nasal obstructive symptom, and general health problems in an adult Korean population.

METHODS

This nationwide study analyzed data from the Korea National Health and Nutritional Examination Survey, 2008-2009. NSD was evaluated by using a nasal endoscope, and a nasal obstructive symptom was assessed via individual interviews. The survey also investigated general health problems, such as medical comorbidity, mental health status, and quality of life. Medical conditions included neurocardiovascular, respiratory, metabolic, musculoskeletal, gastrointestinal, and malignant diseases. To eliminate the effect of combined nasal problems in otorhinolaryngology, subjects with rhinosinusitis and allergic rhinitis were excluded. This study focused on obstructive NSD, which is defined as an anatomic NSD with a chronic nasal obstructive symptom.

RESULTS

We enrolled 8865 participants, and the prevalence of NSD was 44.8%. No general health problems showed a significant association with NSD. However, the prevalence of NSD with an obstructive symptom was 2.1%. Obstructive NSD had no association with all the general health problems, except asthma. A significant association was found between obstructive NSD and asthma (odds ratio 2.648 [95% confidence interval, 1.211-5.791]).

CONCLUSION

Among various general health problems, our study found that NSD was associated with asthma only when NSD was accompanied by a chronic nasal obstructive symptom.

Increased expression of bitter taste receptors in human allergic nasal mucosa and their contribution to the shrinkage of human nasal mucosa

OBJECTIVE

Bitter taste receptors (TAS2Rs) are expressed in the extraoral tissues, where they possess various physiological functions. This study is to characterize TAS2Rs expression in normal and allergic nasal mucosa and analyse nasal symptom after challenge with bitter tastes to evaluate their pathophysiological function in normal and allergic nasal mucosa.

METHODS

The expression levels of TAS2Rs (TAS2R4, 5, 7, 10, 14, 39, and 43) in nasal mucosa were investigated by real-time PCR, Western blot, and immunohistochemistry. The expression levels of TAS2Rs and Ca(2+) imaging in cultured epithelial cells were measured after stimulation with type 2 cytokines (IL-4, IL-5, and IL-13) or bitter tastes. Nasal symptoms in control subjects and allergic rhinitis patients using visual analogue score and acoustic rhinometry were evaluated before and after stimulation with bitter tastes. Vascular diameter of rat nasal septum was measured before and after treatment with bitter tastes.

RESULTS

TAS2Rs tested here were expressed in nasal mucosa where they were commonly distributed in superficial epithelium, submucosal glands, and endothelium. Their expression levels are increased in allergic nasal mucosa and up-regulated in cultured epithelial cells simulated with type 2 cytokines. After treatment with bitter tastes, intracellular Ca(2+) signalling was increased in cultured epithelial cells, and vascular constriction was found in rat nasal septum. Increased nasal patency was observed in human nasal mucosa without pain or sneezing.

CONCLUSION AND CLINICAL RELEVANCE

TAS2Rs are constitutively expressed in human nasal mucosa and their expression levels are increased in allergic nasal mucosa, where they could potentially contribute to shrinkage of normal and allergic nasal mucosa.

Exercise simultaneously increases nasal patency and bronchial obstruction in asthmatic children

We found that simultaneous post-exercise increase in nasal patency and bronchial obstruction occurs only in children with atopic asthma, but not in sensitized children without asthma. In healthy children, the increase in nasal patency is accompanied by bronchial dilatation.

Measurements of nasal airflow and patency: a critical review with emphasis on the use of peak nasal inspiratory flow in daily practice

Objective measures can be used to assist the clinician to diagnose and treat nasal obstruction and also to quantify nasal obstruction in research. Objective measurements of nasal obstruction are as important as objective measurements of lung function. peak nasal inspiratory flow (PNIF), acoustic rhinometry (AR) and rhinomanometry (RM), with their specific peculiarity, assess different aspects of nasal obstruction. From the studies available in the literature, it seems that these methods roughly correlate with each other and that all of them can be alternatively utilized very well in research as well as in clinical practice. This review describes the various methods that can be used to measure nasal patency, airflow and resistance, mainly peak nasal inspiratory flow, rhinomanometry and acoustic rhinometry. PNIF has been demonstrated to be reproducible and as good an indication of objective nasal patency as formal rhinomanometry and has the advantage to be cheap, simple and suitable for serial measurements and for home use even in the paediatric population. PNIF normative data are available for children, adults and elderly subjects, and the availability of unilateral PNIF normal values allows evaluation of nasal sides separately. Just as in the lower airways, objective and subjective evaluation gives different information that together optimizes the diagnosis and the treatment of our patients. We argue that PNIF should be used regularly in every outpatient clinic that treats patients with nasal obstruction.

Paranasal sinus opacification at MRI in lower airway disease (the HUNT study-MRI)

The study builds on the concept of united airways, which describes the link between the upper and lower airways. Explorations of this concept have mainly related to asthma and less to chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate paranasal sinus opacification at magnetic resonance imaging (MRI) in COPD, self-reported asthma and respiratory symptoms. In this cross-sectional study, 880 randomly selected participants in the Nord-Trøndelag health survey (HUNT) (mean age 57.7 years, range 50-66 years, 463 women) were investigated using MRI of the paranasal sinuses. Participants were allocated to four mutually exclusive groups: (1) COPD (n = 20), (2) asthma (n = 89), (3) respiratory symptoms (n = 199), and (4) reference group (n = 572). Paranasal sinus opacifications were categorised as mucosal thickening, polyps and retention cysts, and fluid. In each participant, measurements ≥1 mm from all sinuses were summed to give a total for each category of opacities. The sums for these three categories were further added together, and referred to as the total sum. Using the 75th percentile cut-off values, the likelihood of having paranasal sinus opacifications was more than six times higher in participants with COPD and twice as high in participants with asthma than among the reference group. Respiratory symptoms were only associated with mucosal thickening. The present study shows that paranasal sinus opacification is associated not only with asthma, but also with COPD and respiratory symptoms. This is in accordance with the united airways hypothesis, and should be kept in mind when handling patients with these conditions.