The nasal cycle in health and disease

Whole-Genome Deep Sequencing of the Healthy Adult Nasal Microbiome

This study aimed to determine shifts in microbial populations regarding richness and diversity from the daily use of a popular over-the-counter nasal spray. In addition, the finding of nasal commensal bacterial species that overlap with the oral microbiome may prove to be potential probiotics for the "gateway microbiomes". Nasal swab samples were obtained before and after using the most popular over-the-counter (OTC) nasal spray in 10 participants aged 18-48. All participants were healthy volunteers with no significant medical histories. The participants were randomly assigned a number by randomizing software and consisted of five men and five women. The sampling consisted of placing a nasal swab atraumatically into the nasal cavity. The samples were preserved and sent to Northwestern University Sequencing Center for whole-genome deep sequencing. After 21 days of OTC nasal spray use twice daily, the participants returned for further nasal microbiome sampling. The microbial analysis included all bacteria, archaea, viruses, molds, and yeasts via deep sequencing for species analysis. The Northwestern University Sequencing Center utilized artificial intelligence analysis to determine shifts in species and strains following nasal spray use that resulted in changes in diversity and richness.

Chief Complaint: Nasal Congestion

Nasal obstruction is the subjective perception and objective state of insufficient airflow through the nose. Nasal congestion, conversely, describes a state of not just inadequate airflow or obstructive phenomena but also pressure- and mucus-related states to the patient. Nasal receptors belonging to the transient receptor potential (TRP) protein family mediate the sense of nasal patency via the trigeminal nerve. The transient receptor potential melastatin-8 (TRPM8) responds to temperatures around 8°C to 22°C, and is stimulated by menthol and other cooling agents. The radiant effects of airflow create heat loss to activate these receptors and humans perceive this as nasal patency rather than the direct detection of airflow. The thermovascular state of the mucosa, in conditions such as rhinitis, influence TRPM8 activation. Nasal endoscopy can show signs of rhinitis and should be considered an essential part of the workup of nasal congestion. Efforts to relieve nasal congestion need to manage the mucosal state and surgery needs to ensures that the nasal cavity mucosa is exposed to the cooling effects of airflow rather than simply creating a passage to the nasopharynx.

Lateralisation of nasal cycle is not reflected in the olfactory bulb volumes and cerebral activations

Nasal cycle (NC) is a rhythmic change of lateralised nasal airflow mediated by the autonomous nervous system. Previous studies reported the dependence of NC dominance or more patent side on handedness and hemispheric cerebral activity. We aimed to investigate firstly the possible lateralised effect of NC on olfactory bulb volume and secondly the association of NC with the lateralised cerebral dominance in terms of olfactory processing. Thirty-five subjects (22 women and 13 men, mean age 26 ± 3 years) participated in the study. NC was ascertained using a portable rhino-flowmeter. Structural and functional brain measurements were assessed using a 3T MR scanner. Vanillin odorant was presented during functional scans using a computer-controlled olfactometer. NC was found to be independent of the olfactory bulb volumes. Also, cerebral activations were found independent of the NC during odorant perception. NC potency is not associated with lateralised structural or functional differences in the cerebral olfactory system.

Assessing Nasal Epithelial Dynamics: Impact of the Natural Nasal Cycle on Intranasal Spray Deposition

This study investigated the intricate dynamics of intranasal spray deposition within nasal models, considering variations in head orientation and stages of the nasal cycle. Employing controlled delivery conditions, we compared the deposition patterns of saline nasal sprays in models representing congestion (N1), normal (N0), and decongestion (P1, P2) during one nasal cycle. The results highlighted the impact of the nasal cycle on spray distribution, with congestion leading to confined deposition and decongestion allowing for broader dispersion of spray droplets and increased sedimentation towards the posterior turbinate. In particular, the progressive nasal dilation from N1 to P2 decreased the spray deposition in the middle turbinate. The head angle, in conjunction with the nasal cycle, significantly influenced the nasal spray deposition distribution, affecting targeted drug delivery within the nasal cavity. Despite controlled parameters, a notable variance in deposition was observed, emphasizing the complex interplay of gravity, flow shear, nasal cycle, and nasal morphology. The magnitude of variance increased as the head tilt angle increased backward from upright to 22.5° to 45° due to increasing gravity and liquid film destabilization, especially under decongestion conditions (P1, P2). This study's findings underscore the importance of considering both natural physiological variations and head orientation in optimizing intranasal drug delivery.

Effect of ambient temperature and respiration rate on nasal dominance: preliminary findings from a nostril-specific wearable

The nasal dominance (ND) determination is crucial for nasal synchronized ventilator, optimum nasal drug delivery, identifying brain hemispheric dominance, nasal airway obstruction surgery, mindfulness breathing, and for possible markers of a conscious state. Given these wider applications of ND, it is interesting to understand the patterns of ND with varying temperature and respiration rates. In this paper, we propose a method which measures peak-to-peak temperature oscillations (difference between end-expiratory and end-inspiratory temperature) for the left and right nostrils during nasal breathing. These nostril-specific temperature oscillations are further used to calculate the nasal dominance index (NDI), nasal laterality ratio (NLR), inter-nostril correlation, and mean of peak-to-peak temperature oscillation for inspiratory and expiratory phase at (1) different ambient temperatures of 18 °C, 28 °C, and 38 °C and (2) at three different respiration rate of 6 bpm, 12 bpm, and 18 bpm. The peak-to-peak temperature (Tpp) oscillation range (averaged across participants;n= 8) for the left and right nostril were 3.80 ± 0.57 °C and 2.34 ± 0.61 °C, 2.03 ± 0.20 °C and 1.40 ± 0.26 °C, and 0.20 ± 0.02 °C and 0.29 ± 0.03 °C at the ambient temperature of 18 °C, 28 °C, and 38 °C respectively (averaged across participants and respiration rates). The NDI and NLR averaged across participants and three different respiration rates were 35.67 ± 5.53 and 2.03 ± 1.12; 8.36 ± 10.61 and 2.49 ± 3.69; and -25.04 ± 14.50 and 0.82 ± 0.54 at the ambient temperature of 18 °C, 28 °C, and 38 °C respectively. The Shapiro-Wilk test, and non-parametric Friedman test showed a significant effect of ambient temperature conditions on both NDI and NLR. No significant effect of respiration rate condition was observed on both NDI and NLR. The findings of the proposed study indicate the importance of ambient temperature while determining ND during the diagnosis of breathing disorders such as septum deviation, nasal polyps, nosebleeds, rhinitis, and nasal fractions, and in the intensive care unit for nasal synchronized ventilator.

Analysis of nasal resistance regulation mechanism during postural changes in patients with obstructive sleep apnea by measuring heart rate variability

STUDY OBJECTIVES

Changes in nasal resistance (NR) during postural changes are influenced by venous filling pressure and autonomic nervous system mediation, and heart rate variability (HRV) can reflect changes in the autonomic nervous system. This study aimed to explore the regulatory mechanisms of NR in patients with obstructive sleep apnea (OSA) during postural changes.

METHODS

Healthy controls (apnea-hypopnea index < 5 events/h) and patients with OSA were recruited. NR and electrocardiogram data were collected in sitting, supine, left-lateral, and right-lateral postures. HRV parameters were obtained by analyzing the electrocardiogram data from each posture. Subgroups were divided according to sitting-supine NR changes, and HRV parameters were compared between different postures and groups/subgroups.

RESULTS

In total, 34 healthy controls and 39 patients with OSA (mean apnea-hypopnea index 34.34 ± 22.44 events/h) were recruited. During sitting-supine postural changes, the NR increased in the control group but did not change significantly in the OSA group. None of the autonomic nervous system-related HRV parameters changed significantly. After the groups were divided into NR-elevated and NR-unchanged subgroups, sympathetic activity-related HRV parameters were higher in the NR-unchanged subgroup but only statistically significant in the OSA group. When comparing the left and right postures, there was no significant change in NR; however, the OSA group had lower parasympathetic activity-related HRV parameters when in the right posture.

CONCLUSIONS

During postural changes from the sitting to supine positions, the total NR increases, and this increment is smaller in patients with OSA. This is likely due to overregulation of sympathetic activity, which may occur in patients with OSA.

CITATION

Shi Y, Lou H, Wang H, et al. Analysis of nasal resistance regulation mechanism during postural changes in obstructive sleep apnea patients by measuring heart rate variability. J Clin Sleep Med. 2023;19(4):643-650.

Nasal sprays for treating COVID-19: a scientific note

Clinical management of COVID-19 has been a daunting task. Due to the lack of specific treatment, vaccines have been regarded as the first line of defence. Innate responses and cell-mediated systemic immunity, including serum antibodies, have been the primary focus of practically all studies of the immune response to COVID-19. However, owing to the difficulties encountered by the conventional route, alternative routes for prophylaxis and therapy became the need of the hour. The first site invaded by SARS-CoV-2 is the upper respiratory tract. Nasal vaccines are already in different stages of development. Apart from prophylactic purposes, mucosal immunity can be exploited for therapeutic purposes too. The nasal route for drug delivery offers many advantages over the conventional route. Besides offering a needle-free delivery, they can be self-administered. They present less logistical burden as there is no need for refrigeration. The present article focuses on various aspects of nasal spray for eliminating COVID-19.

Can Upper Airway Surgeries Improve Lower Airway Function ? A Prospective Study

Deviated nasal septum and turbinate hypertrophy are the most common causes for nasal obstruction, which compromise nasal airflow and increases airway resistance. These conditions can further reduce the airflow to lung, which will affect the lung volume and function subsequently reduces the exercise tolerance. The present study aimed to evaluate the impact of upper airway surgeries like septoplasty and turbinoplasty on lower airway functions using simple tests like spirometry and 6 min walking test (6mWt). This research was a prospective study. There were 88 subjects in the study who completed follow up. Spirometry and 6mWt was performed 1 day before and 1 month after surgery in all subjects. Mean preoperative and postoperative values of spirometry (forced vital capacity (FVC),forced expiratory volume in 1 s (FEV1), forced expiratory volume in 1 s/ forced vital capacity (FEV1/FVC), peak expiratory flow rate (PEFR) and 6mWt (systolic blood pressure, diastolic blood pressure, heart rate and oxygen saturation) parameters were compared and analyzed. Percentage of improvement of each parameter was compared with the type of surgery, side of obstruction, age of the patient and duration of symptom. Spirometry showed statistically significant improvement in all 4 parameters after surgery in 86 subjects. 6mWt showed statistically significant improvement in SBP and SpO2 and there was no significant improvement in DBP and HR. We also observed that improvement in parameters was irrespective of age and duration of symptoms. So this study concludes that airway narrowing nasal diseases can compromise lower airway function.

Source terms for benchmarking models of SARS-CoV-2 transmission via aerosols and droplets

There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.

Source terms for benchmarking models of SARS-CoV-2 transmission via aerosols and droplets

There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.

[Definition and illustration of the different types of nasal cycle using long-term rhinometry]

BACKGROUND

A reciprocal swelling of the nasal mucosa is often referred to as the classical nasal cycle; however, reports in the literature suggest a more complex picture. Most of the research on the nasal cycle is based on individual measurements. The long-term rhinometry (LRM) now makes it possible to continuously examine the cyclic swelling of the nasal mucosa over 24 h. The aim of this study was therefore to evaluate the nasal cycle with LRM over 24 h.

MATERIAL AND METHODS

An LRM was performed in 55 rhinologically healthy subjects over 24 h using the portable measuring system Rhino-Move© (Happersberger Otopront; Hohenstein, Germany).

RESULTS

In addition to the expected strictly reciprocal swelling of the nasal mucosa in the sense of the classical nasal cycle, the following cycle types were detected: in-concert type with simultaneous rise and drop of the air flow on both sides of the nose, the one-sided type with significant congestion and decongestion of the mucous membrane only on one side and no detectable changes on the other side of the nose and the non-cycle type without any change in airflow on both sides. Most subjects showed a complex picture with multiple cycle types within the 24 h measurement (mixed nasal cycle). The types often differed during the day and night.

CONCLUSION

This study confirms the assumption that the nasal cycle measured over 24 h is much more complex than often described in the literature. Most subjects showed several of the 5 cycle types described here. The LRM has proven to be an easy to- use and reliable measurement method. The relationship between cycle type and physical activity as well as other factors remains to be investigated.

Inhaled nasopharyngeal nitric oxide concentrations during unilateral nostril breathing - A pilot study

The yogic pranayama technique of unilateral nostril breathing (UNB) has previously demonstrated improvements in language and anxiety in stroke sufferers, as well as reduced blood pressure and increased heart rate in normal healthy adults. The nose typically passes different amounts of air through each nostril with the greater amount of air passing through the 'patent' side, and a lesser amount through the 'congested' side. Each side of the nose periodically takes turns at carrying the dominant tidal air flow in what is termed the' nasal cycle'. The nasal sinuses are a rich source of inhaled nitric oxide, a colourless and odourless gas that acts as a bronchodilator, vasodilator, and neurotransmitter. Nasal derived nitric oxide (NO) may contribute to the benefits attributed to UNB. This investigation seeks to assess the influence the nasal cycle has on inhaled nasopharyngeal NO concentrations during UNB by comparing unobstructed bilateral nostril breathing to patent-side and congested-side UNB in healthy individuals demonstrating a nasal cycle. After determining the patent and congested nasal sides in healthy adult volunteers, and sampling air at both nostrils, nasopharyngeal inhaled NO concentrations were then assessed during normal nasal at-rest tidal breathing during three different nasal breathing states: first both nostrils, then allocated in randomised order, patent side only, and congested side with only UNB. Nasopharyngeal NO concentrations were found to be consistently higher on both exhalation and inhalation during congested side UNB, when compared with either unilateral patent side UNB or breathing through both nostrils.

Nasal Obstruction as a Potential Factor Contributing to Hypoxemia in Obstructive Sleep Apnea

PURPOSE

This study aimed to evaluate the correlation between nasal resistance and oxygen desaturation to better elucidate the role of nasal obstruction in the pathophysiology of obstructive sleep apnea (OSA).

PATIENTS AND METHODS

Eighty-eight OSA patients aged between 22 and 77 years were enrolled in this study. Nasal resistance was measured at pressures of 75, 150, and 300 Pa, with the patients first in the seated position than in the supine position. Relationships between the oximetric variables and nasal resistance in the seated and supine positions were analyzed.

RESULTS

From seated to supine position, a statistically significant increase in nasal resistance was observed at pressures of 75 and 150 Pa (p=0.001 and p=0.006, respectively). Significant positive correlations were noted between nasal resistance in the supine position at 75 Pa (SupineNR75) and oximetry variables, including oxygen desaturation index (ODI, p=0.015) and the percentage of total time with oxygen saturation level lower than 90% (T < 90%, p=0.012). However, significant positive correlations existed only in moderate to severe OSA when the study group was further divided into two subgroups (mild vs moderate to severe OSA). Body mass index (β = 0.476, p<0.001) and SupineNR75 (β = 0.303, p=0.004) were identified as independent predictors for increased ODI.

CONCLUSION

Nasal resistance in the supine position measured at 75 Pa significantly correlated with the severity of oxygen desaturation. Therefore, nasal obstruction may play an important role in the pathophysiology of hypoxemia in OSA patients, especially in patients with moderate to severe OSA.

The role of nasal congestion as a defence against respiratory viruses

Introduction

This review discusses how nasal congestion may have benefits as a mechanism of defence against respiratory viruses.

Methods

A literature research was conducted on respiratory viruses and nasal congestion, following a recently published review on how temperature sensitivity is important for the success of common respiratory viruses.

Results

The literature reported that common respiratory viruses are temperature sensitive and replicate well at the cooler temperatures of the upper airways (32°C), but replication is restricted at body temperature (37°C). The amplitude of the phases of congestion and decongestion associated with the nasal cycle was increased on infection with respiratory viruses and this caused unilateral nasal congestion and obstruction. Nasal congestion and obstruction increase nasal mucosal temperature towards 37°C and therefore restricted the replication of respiratory viruses.

Conclusion

Nasal congestion associated with the nasal cycle may act as a mechanism of respiratory defence against infection with respiratory viruses.

Future Direction in Rhinoplasty: Functional Improvements for a Better Outcome

The nose plays both an aesthetic and functional role in the human body. Physiologically, the nose is an important part of the upper airway. Aesthetically, it is the central focal point of the face. Thus, rhinoplasty has evolved to be both an aesthetic and functional surgery, as the manipulation of the aesthetic subunits of the nose inadvertently leads to the functional alterations of the nose. While the aesthetic goals of rhinoplasty are well described in the literature, functional outcomes from rhinoplasty have been more challenging to delineate. Rhinoplasty can have an impact on the sense of smell, sleep apnea, oxygenation, cognitive function, cardiovascular function, and voice. We have systematically reviewed the current literature in regard to functional rhinoplasty and septoplasty to summarize current surgical maneuvers and their impact on nasal function, along with physiological and perceived functional changes from rhinoplasty.

Relationship Between Nasal Cycle, Nasal Symptoms and Nasal Cytology

Background

The nasal cycle is the spontaneous congestion and decongestion of nasal mucosa that happens during the day. Classically, 4 types of nasal cycle patterns have been described: (1) classic, (2) parallel, (3) irregular, and (4) acyclic. Hypothalamus has been considered as the central regulator even if several external factors may influence its activity.

Objective

The aim of the study was to evaluate the presence of a correlation between nasal cycle pattern, nasal cytology and nasal symptoms.

Methods

Thirty healthy volunteers have been enrolled in the study. All subjects completed a Sino-Nasal Outcome Test-22 questionnaire and a Visual Analog Scale (VAS) for nasal obstruction. The nasal cycle was studied by means of peak nasal inspiratory flow. Nasal cytology has been used to evaluate the presence of local nasal inflammation.

Results

Nineteen subjects showed a parallel nasal cycle pattern, while 11 showed a regular one. A parallel pattern was present in 60% of asymptomatic subjects and in 67% of the symptomatic one ( P = 1). VAS for nasal obstruction did not show a significant difference between the 2 patterns of the nasal cycle ( P = .398). Seventeen subjects had a normal rhinocytogram, while 13 volunteers showed a neutrophilic rhinitis; 53.8% of the subjects with a neutrophilic rhinitis showed a parallel pattern, while the remaining 46.2% had a regular one. In the case of a normal cytology, 70.6% of the volunteers had a parallel pattern and 29.4% had a regular one. Differences between the 2 groups were not statistically significant ( P = .575).

Conclusion

Rhinitis with neutrophils seems to not influence the nasal cycle pattern. Based on the present results, the pattern of nasal cycle does not influence subjective nasal obstruction sensation.

[Airway anatomy : Relevant structures in emergency medicine]

The subject of this article is the anatomy of the respiratory tract with an emphasis on the larynx. A differentiation is made between the upper and lower airways according to topographical and functional aspects, the limits of which are marked by the lower section of the larynx. The focus is on the anatomy of the structures involved, which are relevant for emergency medicine.

Validity of rhinometry in measuring nasal patency for nasotracheal intubtion

PURPOSE

Numerous techniques have been used to reduce epistaxis during nasotracheal intubation. Rhinometry can assess nasal patency in preoperative conditions. However, the possible role of rhinometry in routine nasotracheal intubation has not been studied.

METHODS

One hundred and one patients undergoing dental and maxillofacial surgery that required general anesthesia and nasotracheal intubation were enrolled. We examined whether symmetry or any asymmetry in bilateral airflow patterns by condensation of the expiration, assessed by preoperative rhinometry on seated position, increased the incidence of epistaxis and the need for a nasogastric catheter to guide the endotracheal tube into the oropharynx. We also compared the incidence of changing the site of nasal intubation between the assessment by rhinometry and by cone-beam computed tomography analysis of nasal airspace in the inferior meatus.

RESULTS

Patients with any asymmetry in bilateral airflow patterns were 18 % (n = 18), the remaining 82 % (n = 83) had symmetric bilateral nasal cavities. Patients with any asymmetry were more likely to need a guiding nasogastric catheter than patients with symmetry (22 vs. 3.6 %, p = 0.018). The incidence of epistaxis was higher in patients with any asymmetry (39 %) than those with symmetry (16 %), but there was no significant difference between groups (p = 0.055). The site of intubation was changed more frequently based on cone-beam computed tomography analysis than by rhinometry (38 vs. 11 %, p = 0.043).

CONCLUSION

Preoperative rhinometry may be a valuable objective tool to assess nasal patency for nasotracheal intubation in patients who undergo dental and maxillofacial surgery.

Measuring and Characterizing the Human Nasal Cycle

Nasal airflow is greater in one nostril than in the other because of transient asymmetric nasal passage obstruction by erectile tissue. The extent of obstruction alternates across nostrils with periodicity referred to as the nasal cycle. The nasal cycle is related to autonomic arousal and is indicative of asymmetry in brain function. Moreover, alterations in nasal cycle periodicity have been linked to various diseases. There is therefore need for a tool allowing continuous accurate measurement and recording of airflow in each nostril separately. Here we provide detailed instructions for constructing such a tool at minimal cost and effort. We demonstrate application of the tool in 33 right-handed healthy subjects, and derive several statistical measures for nasal cycle characterization. Using these measures applied to 24-hour recordings we observed that: 1: subjects spent slightly longer in left over right nostril dominance (left = 2.63 ± 0.89 hours, right = 2.17 ± 0.89 hours, t(32) = 2.07, p < 0.05), 2: cycle duration was shorter in wake than in sleep (wake = 2.02 ± 1.7 hours, sleep = 4.5 ± 1.7 hours, (t(30) = 5.73, p < 0.0001). 3: slower breathing was associated with a more powerful cycle (the extent of difference across nostrils) (r = 0.4, p < 0.0001), and 4: the cycle was influenced by body posture such that lying on one side was associated with greater flow in the contralateral nostril (p < 0.002). Finally, we provide evidence for an airflow cycle in each nostril alone. These results provide characterization of an easily obtained measure that may have diagnostic implications for neurological disease and cognitive state.

Nasal airflow and brain activity: is there a link?

BACKGROUND

Over the past few decades, evidence has emerged suggesting that nasal airflow asymmetry and brain asymmetry are linked. The nose exhibits asymmetrical airflow, with the dominant airflow alternating from one nasal passage to the other over a period of hours. Some authors have suggested a correlation between cerebral hemisphere dominance and nostril dominance. Others have proposed an association between rhythmic fluctuations in nasal airflow and corresponding fluctuations in cerebral hemisphere activity. Based on ancient yoga breathing techniques, newer evidence suggests that altering nasal airflow can influence brain activity, with reports of improved cognitive function caused by unilateral forced nostril breathing. It seems that a nasal airflow stimulus may have an activating effect on the brain, as it has also been shown to trigger seizure activity in epileptic patients.

OBJECTIVES

This article explores these theories in detail, reviews the evidence, and presents new models linking nasal airflow and brain activity.

Nasal airway responses to nasal continuous positive airway pressure breathing: An in-vivo pilot study

The nasal cycle, through variation in nasal airflow partitioning, allows the upper airway to accommodate the contrasting demands of air conditioning and removal of entrapped air contaminants. The purpose of this study was to investigate the influence of nasal continuous positive airway pressure (nCPAP) breathing has on both nasal airflow partitioning and nasal geometry. Using a custom-made nasal mask, twenty healthy participants had the airflow in each naris measured during normal nasal breathing followed by nCPAP breathing. Eight participants also underwent magnetic resonance imaging (MRI) of the nasal region during spontaneous nasal breathing, and then nCPAP breathing over a range of air pressures. During nCPAP breathing, a simultaneous reduction in airflow through the patent airway together with a corresponding increase in airway flow within the congested nasal airway were observed in sixteen of the twenty participants. Nasal airflow resistance is inversely proportional to airway cross-sectional area. MRI data analysis during nCPAP breathing confirmed airway cross-sectional area reduced along the patent airway while the congested airway experienced an increase in this parameter. During awake breathing, nCPAP disturbs the normal inter-nasal airflow partitioning. This could partially explain the adverse nasal drying symptoms frequently reported by many users of this therapy.

Decrease of nasal airway resistance and alleviations of symptoms after balloon sinuplasty in patients with isolated chronic rhinosinusitis: a prospective, randomised clinical study

OBJECTIVES

The aim of this study was to evaluate and compare the clinical outcome of balloon sinuplasty and uncinectomy for patients suffering from isolated chronic rhinosinusitis of the maxillary sinus.

DESIGN

A prospective, randomised, non-blinded, controlled trial was conducted.

SETTING

The study was carried out at the Department of Otolaryngology, Tampere University Hospital, Finland.

PARTICIPANTS

Adult patients with symptomatic isolated chronic or recurrent rhinosinusitis without severe findings in the sinuses, as documented in the sinus' Computer Tomography scan and clinical examination, were randomised into two groups: uncinectomy and balloon sinuplasty.

MAIN OUTCOME MEASURES

The variables in our study are the Sinonasal Outcome Test-22 (SNOT 22), acoustic rhinometry and rhinomanometry. These parameters were analysed preoperatively and postoperatively (after 3 and 6 months).

RESULTS

The preliminary results of our study have been previously published. Both balloon sinuplasty and uncinectomy significantly improved almost all the parameters of SNOT22 (P < 0.05), with no significant difference being found between these two groups (P > 0.05). Based on rhinomanometry results, airway resistance decreased after treatment. Regarding adverse effects, balloon sinuplasty was significantly associated with a lesser risk of synechia.

CONCLUSIONS

Both balloon sinuplasty and uncinectomy improved the quality of life and decreased upper airway resistance of patients with mild, isolated chronic or recurrent rhinosinusitis. The smaller risk of postoperative synechiae with balloon sinuplasty combined with its promising efficiency could partially compensate for its high material cost.

A model for the central control of airflow patterns within the human nasal cycle

BACKGROUND

The nasal cycle exhibits mainly reciprocal changes in nasal airflow that may be controlled from centres in the hypothalamus and brainstem. This study aims to gather new knowledge about the nasal cycle to help develop a control model.

METHOD

Right and left nasal airflow was measured in healthy human subjects by rhinomanometry. This was performed over 7-hour periods on 2 study days separated by approximately 1 week. The correlation coefficient for nasal airflow was calculated for day 1 and day 2.

RESULTS

Thirty subjects (mean age, 22.7 years) completed the study. The correlation coefficient for nasal airflow varied between r = 0.97 with in-phase changes in airflow and r = -0.89 with reciprocal changes in airflow. The majority of r values were negative, indicating reciprocal changes in airflow (50 out of 60). There was a tendency for r values to become more negative between day 1 and day 2 (p < 0.001).

CONCLUSION

A control model involving a hypothalamic centre and two brainstem half centres is proposed to explain both the in-phase and reciprocal changes in airflow associated with the nasal cycle.

Model demonstrates functional purpose of the nasal cycle

Background

Despite the occurrence of the nasal cycle being well documented, the functional purpose of this phenomenon is not well understood. This investigation seeks to better understand the physiological objective of the nasal cycle in terms of airway health through the use of a computational nasal air-conditioning model.

Method

A new state-variable heat and water mass transfer model is developed to predict airway surface liquid (ASL) hydration status within each nasal airway. Nasal geometry, based on in-vivo magnetic resonance imaging (MRI) data is used to apportion inter-nasal air flow.

Results

The results demonstrate that the airway conducting the majority of the airflow also experiences a degree of ASL dehydration, as a consequence of undertaking the bulk of the heat and water mass transfer duties. In contrast, the reduced air conditioning demand within the other airway allows its ASL layer to remain sufficiently hydrated so as to support continuous mucociliary clearance.

Conclusions

It is quantitatively demonstrated in this work how the nasal cycle enables the upper airway to accommodate the contrasting roles of air conditioning and the removal of entrapped contaminants through fluctuation in airflow partitioning between each airway.

Swelling of Erectile Nasal Tissue Induced by Human Sexual Pheromone

Most chemically mediated sexual communication in humans remains uncharacterized. Yet the study of sexual communication is decisive for understanding sexual behavior and evolutive mechanisms in our species. Here we provide the evidence to consider 4,16-androstadien-3-one (AND) as a man's sexual pheromone. Our experiment provides support for the physiological effect of AND on nasal airway resistance (Rna) in women, as assessed by anterior rhinomanometry. We found that AND administration increased the area of turbinate during the ovulatory phase, resulting in an increase of Rna. Thus, we discovered that minute amounts of AND, acting through neuroendocrine brain control, regulate Rna and consequently affect the sexual physiology and behavior. Fascinatingly, this finding provides the evidence of the preservation of chemosexual communication in humans, which it has been largely neglected due to its unconscious perception and concealed nature. Therefore, chemical communication is a plesiomorphic evolutive phenomenon in humans.

Effects of radiofrequency thermal ablation on the nasal cycle measured using rhinomanometry

OBJECTIVE

This study was designed to research the effects of radiofrequency thermal ablation (RFTA) surgery on the nasal cycle, with anterior rhinomanometry being used for assessment.

METHODS

Thirty patients with inferior concha hypertrophy and 13 healthy volunteers were included in this study. An anterior rhinomanometry was performed on each of the patients before surgery and at 1 month and 6 months after surgery, and on the volunteers in the control group, simultaneously.

RESULTS

Nineteen of the 30 patients and 8 of the 13 healthy participants showed a distinct type of nasal cycle at different periods of measurement. The mean of the total nasal airflow of the patients was lower before RFTA surgery but increased at a rate of 71.07%, closer to the value of the control group, after RFTA surgery. After RFTA, the unilateral nasal airflow (fmin and fmax) values increased at ratios of 22.36% and 94.44%, respectively. The amplitude (fmax-fmin) showed a statistically significant decrease in the postoperative period (108.43 ± 54.37), when compared with that of the preoperative period (202.80 ± 81.24) (P < .01).

CONCLUSION

We conclude that the RFTA is a useful method for treating inferior concha hypertrophy, because it positively affects the nasal physiology, increasing the total nasal airflow without changing the nasal cycle time.

Total nasal resistance among Sasang constitutional types: a population-based study in Korea

Background

There have been many attempts to find an objective phenotype by Sasang constitutional types (SCTs) on an anatomical, physiological, and psychological basis, but there has been no research on total nasal resistance (TNR) among SCTs.

Methods

We assessed the value of the TNR in the SCTs classified by an integrated diagnostic model. Included in the study were 1,346 individuals (701 males, 645 females) who participated in the Korean Genome and Epidemiology Study (KoGES). The TNR was measured by active anterior rhinomanometry (AAR) at transnasal pressures of 100 and 150 Pascal (Pa).

Results

The average TNR was 0.186 ± 0.004 Pa/cm³/second at 100 Pa in the Tae-eum (TE), 0.193 ± 0.007 in the So-eum (SE), and 0.208 ± 0.005 in the So-yang (SY) types. Under condition of 150 Pa the TE type had a TNR value of 0.217 ± 0.004, the SE type was 0.230 ± 0.008, and the SY type was 0.243 ± 0.005. Higher values of TNR were more likely to be reported in the SY type at 100 Pa and 150 Pa. In the stratified analysis by sex, the SY type in males and females tended to have higher TNR value than the TE and SE types at transnasal pressure of both 100 Pa and 150 Pa.

Conclusions

These results provide new approaches to understand the functional characteristics among the SCTs in terms of nasal physiology. Further studies are required to clarify contributing factors for such a difference.

Frictional resistance sheds light on the multicomponent nature of nasal obstruction: a combined in vivo and computational fluid dynamics study

Exploring nasal flow contributes to better understanding of pathophysiological functions of nasal cavities. We combined the rhinomanometry measurements of 11 patients and computational fluid dynamics (CFD) simulations in 3 nasal airway models to dissect the complex mechanisms that determine nasal flow obstruction: spatial complexity and pressure-dependent deformability of nasal airways. We quantified spatial complexity by calculating longitudinal variations of hydraulic diameter, perimeter and area of nasal cavities, and their impact on flow characteristics by examining the longitudinal variations of the kinetic energy coefficient and the kinetic to potential energy ratio. Airway distensibility variably affected in vivo pressure-flow relationships through the appearance of flow-limitation patterns characterized by maximum flow and/or flow plateau. We quantified deformability and spatial complexity effects on nasal airway resistance by normalizing all data with averaged reference parameters. The results show that discrepancies in nasal flow resistances reflect airway deformability and geometrical complexity, and thereby constitute a framework to better characterize nasal obstruction.

The importance of side difference in nasal obstruction and rhinomanometry: a retrospective correlation of symptoms and rhinomanometry in 1000 patients

OBJECTIVES

The correlation between subjective and objective outcomes of nasal obstruction is still a matter of controversy. The aim of this study was to determine the minimal level of side difference in nasal airway resistance (NAR measured by Broms'v(2)) between the two nasal cavities, which could be discerned subjectively by the patient on a visual analogue scale (VAS). Nasal airway resistance was calculated from rhinomanometric measurements of nasal airflow and transnasal pressure after decongestion of the nasal mucosa.

DESIGN

A retrospective study.

SETTING

ENT department, Vaxjo Central Hospital, Sweden.

PARTICIPANTS

We studied 1000 active anterior rhinomanometries from patients with nasal obstructions.

MAIN OUTCOME MEASURES

We compared the side difference of nasal airway resistance with the side difference of VAS estimated immediately prior to the rhinomanometry. Each measurement was performed after nasal decongestion.

RESULTS

When the difference in nasal airway resistance between the two nasal cavities was larger than 20° (Broms'v(2)) or R(2) > 0.36 Pa/cm(3) /s, we found a significant correlation between side differences of the objective measurement and the subjective assessment (VAS). With a nasal airway resistance side difference over 20°, an additional 20° difference corresponded to a 0.9 centimetre average VAS change. The more obstructed side of the nose could be determined by VAS in 823 (82.3%) of 1000 patients. Yet, 177 (17.7%) patients had a paradoxical sensation of nasal obstruction with the low resistance side of the nose experienced as the most congested side.

CONCLUSION

A significant correlation between the side differences of nasal airway resistance and VAS can serve as a supplement to rhinoscopy in decisions about nasal surgery. This study also showed that in 17.7% of patients, there was a negative correlation between subjective and objective evaluations of nasal airway resistance. But in this group, the nasal airway resistance side difference was mostly under 20°.

Comparative evaluation of nasal blood flow and airflow in the decongestant response to oxymetazoline

BACKGROUND

Nasal blood flow (NBF) plays a crucial role in many physiological and pathological processes but its regulation and relation to other rhinological outcomes is poorly understood.

OBJECTIVES

We measured nasal airway patency, nasal blood flow, and subjective and objective measures of decongestion and assessed their reproducibility and responsiveness.

METHODS

19 healthy adults attended twice. A dose-response curve was constructed using doubling doses of oxymetazoline of 25 μg, 50 μg, 100 μg, and 200 μg at 20 minute intervals. Peak nasal inspiratory flow (PNIF) and nasal airway resistance (NAR) were measured at baseline and after each successive dose, NBF using laser Doppler flowmetry at baseline, 50 μg and 200 μg and a decongestion visual analogue scale after the final dose.

RESULTS

After the final dose of oxymetazoline, NBF decreased by a mean (95% CI, P value) of 139.6 (108.3-170.8, P < .001) units and 99.4 (68.1-130.7, P < .001) units, PNIF increased by 48.9 (22.0-75.8, P < .001) L.min-1 and 38.9 (12.0-65.8, P = .003) L.min-1, and NAR decreased by 0.1 (0.02-0.15, P < .001) Pa/s/cm(3) and 0.09 (0.02-0.15, P = .002) Pa.s.cm-3 at the first and second visits respectively. The area under the curve of decongestion was not significantly different between visits for each variable. The standardized response means for the decongestant response were as follows: NBF, 1.41; PNIF, 1.03; and NAR, 0.97.

CONCLUSIONS

Nasal blood flow using laser Doppler flowmetry is a sensitive and reproducible outcome to decongestion with oxymetazoline, similar to nasal patency and symptoms.

CLINICAL TRIALS REGISTRATION

www.clinicaltrials.gov (NCT 00487032).

Correlation of nasal morphology to air-conditioning and clearance function

Nasal morphology plays an important functional role in the maintenance of upper airway health. Identification of functional regions, based on morphological attributes, assists in correlating location to primary purpose. The effects of morphological variation on heat and water mass transport in congested and patent nasal airways were investigated by examining nasal cross-sectional MRI images from 8 healthy subjects. This research confirms the previous identification of functional air-conditioning regions within the nose. The first is the anterior region where the morphology prevents over-stressing of tissue heat and fluid supply near the nares. The second is the mid region where low flow velocity favours olfaction and particle deposition. The third is the posterior region which demonstrates an increase in heat and water mass flux coefficients to compensate for rising air humidity and temperature. Factors identified within the congested airway that favour enhanced mucocillary clearance were also identified.

'Valve-stabilised' rhinospirometry can predict the benefit of septal surgery: a pre- and post-operative correlation study

Septoplasty is a procedure often associated with high levels of patient dissatisfaction post-operatively. This study examined whether rhinospirometry and a modified 'valve-stabilised' technique could pre-operatively predict the outcome of septal surgery and therefore have a role as an objective tool for selection of patients suffering from nasal obstruction due to septal deformity for the procedure of septoplasty. A prospective study was performed of patients attending Singleton Hospital, Swansea, for surgical treatment of nasal obstruction due to septal deformity. Participants were asked to undertake decongested visual analogue scoring (VAS) and rhinospirometric assessment of their nasal obstruction in both normal 'resting' and 'valve-stabilised' nasal positioning. These investigations were undertaken on the day of surgery and 6 weeks post-operatively. Results were converted into nasal partition ratio scores and were assessed statistically for difference, correlation and accuracy. A total of 29 individual participants were included in the study. Septal surgery produced a statistically significant improvement in nasal airflow symmetry in the normal 'resting' nasal position using rhinospirometry (Wilcoxon ranked p > 0.5). This difference was not seen between evaluations in 'valve-stabilised' position (Wilcoxon p < 0.001). No statistical difference was evident between pre-operative 'valve-stabilised' testing and post-operative 'resting position'. The finding was also apparent on VAS nasal assessment. Correlation studies showed a strong relationship between pre-operative 'valve-stabilised' and post-operative 'resting' rhinospirometry results (Spearman's rho = 0. 586, p < 0.002). The strength of this relationship between VAS assessments was less pronounced (Spearman's rho = 0.386 p = 0.07). 'Valve-stabilised' rhinospirometry and VAS appear to be useful pre-operatively to predict the outcome of septal surgery, in terms of airflow symmetry, for nasal obstruction due to septal deformity, with pre-operative 'valve-stabilised' results correlating well with the post-operative standard 'resting' outcomes. Valve-stabilised rhinospirometry may have a role in pre-operatively predicting of likely post-operative patient satisfaction, although further studies are required in this area.

[Nasal-air conditioning]

INTRODUCTION

We present a review of nasal-air conditioning, a process essential to undisturbed gas exchange and cleansing of the respiratory mucosa in the nose.

METHODS

A selective literature review was made on the basis of in vivo measurements and computer simulation of the upper airways as well as the authors' own clinical and experimental data.

RESULTS AND DISCUSSION

Healthy subjects normally breathe through the nose, although the nasal airways have significantly higher airway resistance compared to the oral cavity, which is opened for breathing during exercise, in the case of nasal airway blockage, or in allergic rhinitis. In addition to olfaction, the main tasks of nasal breathing include: cleansing, defense, and conditioning (i.e., humidification and heating). The current knowledge of nasal conditioning processes will be discussed. In addition, research activities of particular relevance for diagnosis and intervention in various pathologies of the upper airways will be presented.

Inferior turbinate surgery and nasal airflow: evidence-based management

PURPOSE OF REVIEW

This review will discuss the evidence-based management of enlarged inferior turbinate by considering methods of assessing nasal airflow, controversies surrounding patient selection and surgical outcomes.

RECENT FINDINGS

There is currently no consensus on patient selection for turbinate surgery. Patients are empirically offered surgery on the basis of subjective complaint of nasal obstruction and surgeon's clinical examination. Few authors have utilized objective measurements of nasal airflow such as rhinomanometry to select suitable patients for surgery. There is a small body of evidence suggesting that more robust criteria of selecting patients, using a nasal decongestant test and rhinomanometry, may have some influence on the surgical outcome. Although most surgical techniques demonstrate improvement in postoperative nasal airflow and subjective scores, it is impossible to draw conclusions as to which technique is best suited for treating inferior turbinate enlargement. The heterogeneous study cohorts, differing patient selection criteria and outcome measures used do not allow meta-analysis of outcomes and comparison between surgical techniques.

SUMMARY

Inferior turbinate surgery is an evolving operative concept and the evidence supporting the efficacy of the various techniques remains undecided. More prospective controlled studies are needed with both objective and subjective outcome measures.

Inflow boundary profile prescription for numerical simulation of nasal airflow

Knowledge of how air flows through the nasal passages relies heavily on model studies, as the complexity and relative inaccessibility of the anatomy prevents detailed in vivo measurement. Almost all models to date fail to incorporate the geometry of the external nose, instead employing a truncated inflow. Typically, flow is specified to enter the model domain either directly at the nares (nostrils), or via an artificial pipe inflow tract attached to the nares. This study investigates the effect of the inflow geometry on flow predictions during steady nasal inspiration. Models that fully replicate the internal and external nasal airways of two anatomically distinct subjects are used as a reference to compare the effects of common inflow treatments on physiologically relevant quantities including regional wall shear stress and particle residence time distributions. Inflow geometry truncation is found to affect flow predictions significantly, though slightly less so for the subject displaying more pronounced passage area contraction up to the internal nasal valve. For both subject geometries, a tapered pipe inflow provides a better approximation to the natural inflow than a blunt velocity profile applied to the nares. Computational modelling issues are also briefly outlined, by comparing quantities predicted using different surface tessellations, and by evaluation of domain-splitting techniques.

Mechanics of airflow in the human nasal airways

The mechanics of airflow in the human nasal airways is reviewed, drawing on the findings of experimental and computational model studies. Modelling inevitably requires simplifications and assumptions, particularly given the complexity of the nasal airways. The processes entailed in modelling the nasal airways (from defining the model, to its production and, finally, validating the results) is critically examined, both for physical models and for computational simulations. Uncertainty still surrounds the appropriateness of the various assumptions made in modelling, particularly with regard to the nature of flow. New results are presented in which high-speed particle image velocimetry (PIV) and direct numerical simulation are applied to investigate the development of flow instability in the nasal cavity. These illustrate some of the improved capabilities afforded by technological developments for future model studies. The need for further improvements in characterising airway geometry and flow together with promising new methods are briefly discussed.

Effect of postural change on nasal airway and autonomic nervous system established by rhinomanometry and heart rate variability analysis

BACKGROUND

Clinically, nasal obstruction is experienced frequently in the supine position, and the nasal autonomic nervous system (ANS) may be involved in the mechanism. The central ANS functions at maintaining cardiovascular hemodynamics. However, during postural change, the corresponding changes of the central ANS may simultaneously change the nasal airway as well. In this study, the relationships between nasal ANS and central ANS were explored using rhinomanometry (RMM) and heart rate variability (HRV) analysis between postural changes.

METHODS

Twelve healthy volunteers aged between 19 and 39 years and without a history of allergic rhinitis or significant nasal anatomic obstruction were enrolled for the study. The nasal airway was measured using RMM in a sitting position and then in a supine position; the electrocardiography was simultaneously recorded.

RESULTS

In supine position, the total nasal airflow significantly decreased and the airway resistance significantly increased (p<0.05, Wilcoxon signed-rank test). The ratio of low frequency power to high frequency (HF) power of HRV that represents sympathetic modulation significantly decreased in the supine position (p<0.05, Wilcoxon signed-rank test). However, the HF that represents parasympathetic activity did not show significant change with postural change. The correlations of heartbeat interval with total inspiratory airflow and total inspiratory resistance were significant also (p<0.01, Pearson's correlation).

CONCLUSION

The central ANS activities significantly correlated with changes to the nasal airway during postural change. The central ANS, especially the sympathetic nervous system, may play a role in controlling nasal airway during postural change.

A Review of the Effects of Expansion of the Nasal Base on Nasal Airflow and Resistance

PURPOSE

The purpose of this article is to inform the reader of the current literature regarding nasal airflow resistance. The anatomy and physiology of nasal airflow resistance will be examined and the known effects of widening of the nasal airway upon airflow will be described.

MATERIALS AND METHODS

This article is a review of the current literature regarding nasal airflow and resistance and the effects of widening of the nasal base. No patient data were collected.

RESULTS

The literature shows that nasal airflow resistance can be changed by surgical manipulation and by rapid palatal expansion, but that the effects on airflow resistance and future growth and development are unpredictable.

CONCLUSION

Patients with a maxilla that is constricted in the transverse dimension and nasal airflow problems may benefit from expansion of the nasal base. The resultant effects upon nasal airflow resistance and subsequent growth and development are unpredictable and therefore airflow issues alone may not be a primary reason to increase the transverse dimension of the nasal base.

Sleep, breathing and the nose

During sleep there is a discrete fall in minute ventilation and an associated increase in upper airway resistance. In normal subjects, the nasal part of the upper airway contributes only little to the elevation of the total resistance, which is mainly the consequence of pharyngeal narrowing. Yet, swelling of the nasal mucosa due to congestion of the submucosal capacitance vessels may significantly affect nasal airflow. In many healthy subjects an alternating pattern of congestion and decongestion of the nasal passages is observed. Some individuals demonstrate congestion of the ipsilateral half of the nasal cavity when lying down on the side. Nasal diseases, including structural anomalies and various forms of rhinitis, tend to increase nasal resistance, which typically impairs breathing via the nasal route in recumbency and during sleep. A role of nasal obstruction in the pathogenesis of sleep-disordered breathing has been implicated by many authors. While it proves difficult to show a relationship between the degree of nasal obstruction and the number of disturbed breathing events, the presence of nasal obstruction will most likely have an impact on the severity of sleep-disordered breathing. Identification of nasal obstruction is important in the diagnostic work-up of patients suffering from snoring and sleep apnea.