The Central Rhythm of the Nasal Cycle

Nasal Breathing Assessment Using Computational Fluid Dynamics: An Update from the Rhinologic Perspective

An objective assessment of nasal breathing is currently insufficiently achievable. The application of computational fluid dynamics for this purpose is increasingly gaining attention. However, the suggested specific frameworks can differ considerably. To the best of our knowledge, there is not yet a widely accepted clinical usage of computational fluid dynamics. In this article, selected aspects are addressed that might be crucial for future development and possible implementation of computational fluid dynamics in rhinology.

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.

The effect of decongestion on nasal airway patency and airflow

Nasal decongestant reduces blood flow to the nasal turbinates, reducing tissue volume and increasing nasal airway patency. This study maps the changes in nasal anatomy and measures how these changes affect nasal resistance, flow partitioning between superior and inferior cavity, flow patterns and wall shear stress. High-resolution MRI was applied to capture nasal anatomy in 10 healthy subjects before and after application of a topical decongestant. Computational fluid dynamics simulated nasal airflow at steady inspiratory flow rates of 15 L.min[Formula: see text] and 30 L.min[Formula: see text]. The results show decongestion mainly increases the cross-sectional area in the turbinate region and SAVR is reduced (median approximately 40[Formula: see text] reduction) in middle and lower parts of the cavity. Decongestion reduces nasal resistance by 50[Formula: see text] on average, while in the posterior cavity, nasal resistance decreases by a median factor of approximately 3 after decongestion. We also find decongestant regularises nasal airflow and alters the partitioning of flow, significantly decreasing flow through the superior portions of the nasal cavity. By comparing nasal anatomies and airflow in their normal state with that when pharmacologically decongested, this study provides data for a broad range of anatomy and airflow conditions, which may help characterize the extent of nasal variability.

Nasal response to stress test in healthy subjects: an experimental pilot study

PURPOSE

Stress has been suspected to play a role in rhinitis. The role of stress on nasal patency has been not yet elucidated. The aim was to evaluate the potential effects of stress on nasal patency in healthy subjects.

METHODS

We conducted a prospective pilot study including 12 healthy subjects. Experimental protocol was divided in three periods (pre-task, task and recovery). In the task period, subjects were exposed to the "Trier Social Stress Test" (TSST), a standardized laboratory stressor. Different parameters including Spielberger State Anxiety Inventory (SSAI) score, visual analogic scale (VAS) of nasal patency feeling, heart rate, acoustic rhinometry measurements have been compared between the three different periods. The study population was divided into two groups according to the Spielberger Trait Anxiety Inventory (STAI) score: A "non anxious" group and a "weakly anxious" group.

RESULTS

Seven subjects were in the "non anxious" group and five in the "weakly anxious" group. TSST significantly increased heart rate in all volunteers. SSAI score was significantly increased (p = 0.04) after the task period (36.6 ± 11.3) when compared to the SSAI score in pre-task period (31.9 ± 12.6). VAS score of nasal patency feeling significantly decreased from pre-task to task and recovery periods. Mean minimal cross-sectional areas and mean volumes of the nasal cavities were not significantly different between the three periods, except in "weakly anxious" group, but the small number of subjects does not allow to draw a definite conclusion.

CONCLUSION

We observed that stress influenced the feeling of nasal patency in healthy subjects. However, the objective effects of stress on nasal geometry were globally non-significant except in "weakly anxious" group. This latter result of our pilot study needs to be confirmed in a larger cohort.

Exercise-Induced Nasal Obstruction in Patients with Allergic Rhinitis

Exercise-induced nasal obstruction was studied in 90 patients with allergic rhinitis and 26 normal subjects. Allergic patients as well as normal subjects showed marked decreases of nasal resistance immediately after exercise. In allergic patients, however, the total nasal resistance returned to the pre-exercise level quickly after exercise and surpassed it. Meanwhile, the total nasal resistance gradually returned to the pre-exercise level in the post-exercise period in normal subjects. The profile of the total nasal resistance changes in the allergic patients was statistically different from that in the normal subjects. As far as unilateral nasal resistance is concerned, marked increases of nasal resistance appeared 10–30 minutes after exercise in 20 of 90 allergic patients. On the contrary, this phenomenon was not found in any normal subject. This unilateral nasal obstruction, which appeared only in allergic patients, is probably due to excessive dilatation of the capacitance vessels in the nasal mucosa and considered to appear as an enhancement of the nasal cycle. In this paper, the role of the nasal cycle is discussed in relation to exercise-induced nasal obstruction.

Effects of Posture on the Nasal Cycle

The effects of posture on the nasal cycle were studied in 26 normal subjects whose spontaneous nasal cycle had been confirmed before the experiment. Nasal resistance was measured by anterior rhinomanometry with nozzles. With 14 subjects, the changes in nasal resistance were observed consecutively on changing from sitting to supine and from supine to sitting. Six reversals of the cyclic phase occurred in 56 postural changes (reversal rare: 10.7%). The reversal occurred once per 2.9 hours. By contrast, with 12 subjects, 27 reversals were induced in 60 postural changes (reversal rate: 45%), on changing from one lateral recumbent position to the other. The reversal occurred once per 27 minutes. Lateral recumbency tends to switch the phase of the cycle and affects its duration.

Airflow and the Nasal Cycle: Nasal Patency Fluctuations after Laryngectomy

A periodic fluctuation in nasal patency or “nasal cycle” is observed in the majority of adults but has not hitherto been demonstrated in individuals after diversion of nasal airflow. Acoustic rhinometry, a highly sensitive technique which does not require airflow, provided the opportunity to evaluate this situation in patients who had undergone laryngectomy. We examined 21 postoperative individuals (mean postoperative time 4 years) and 14 control subjects matched for age (including 2 patients prelaryngectomy). Acoustic rhinometry was performed serially over 3–8 hours to determine minimum cross-sectional area and nasal cavity volume as indices of nasal patency. Fluctuations in nasal patency were observed in all laryngectomees and controls. These were classified as classical (reciprocal alternating), in concert (parallel) or irregular. The distribution of the control and laryngectomy subjects between the cycle categories was not statistically significant (Fisher's exact test: P > 0.05). The mean periodicity of the cycle was similar in the two groups (controls: 180 minutes, laryngectomees: 176 minutes), but the mean amplitude was significantly less in the laryngectomy group (68 versus 96 cm3; P < 0.07 Mann-Whitney U test). The nasal cycle can continue after cessation of airflow, but it is diminished in amplitude. Therefore, afferent input from nasal airflow receptors may continue to play a role in modulating the cycle's periodicity and amplitude, but are not responsible for generating the underlying cycle phenomenon.

The nasal cycle and age

CONCLUSION

The reciprocal nature of the nasal cycle declined with age in keeping with other published data, suggesting that studies of the nasal cycle may be a useful measure of central nervous system (CNS) disease and aging.

OBJECTIVES

The aim of this study was to investigate changes in the nasal cycle with age.

METHODS

In one male subject changes in nasal airflow were measured by anterior rhinomanometry to determine the reciprocal nature of the 'nasal cycle' at age 28 and again at age 66 years.

RESULTS

Significant reciprocity was demonstrated in the historical study (age 28 years) with correlation coefficients for the 3 study days of -0.81, -0.83 and -0.79. compared with the current study (age 66 years) where non-significant correlation coefficients of 0.02 and -0.43 were obtained.

Asymmetric nasal mucosal thickening in healthy dogs consistent with the nasal cycle as demonstrated by MRI and CT

The nasal cycle is a physiological phenomenon that causes regular cyclical congestion and decongestion of the venous sinusoids lining the nasal mucosa. The purpose of this prospective study was to describe magnetic resonance imaging (MRI) and computed tomographic (CT) features of the normal nasal cycle in a group of dogs. Five dogs were recruited that met the following criteria: 8 to 15 months old, nonbrachiocephalic breed, no clinical signs or history of nasal disease, and undergoing anesthesia for problems unrelated to the nasal cavity. Nasal MRI (n = 5) and CT scans (pre- and postcontrast, n = 5) were acquired. Images were evaluated subjectively by two board-certified radiologists and objectively by a diagnostic imaging intern using regions of interest placed on each side of the nasal cavity. Findings were compared using Cohen's kappa coefficient and Students t-test on log-transformed data. All dogs showed diffuse unilateral mucosal thickening of the rostral part of the nasal cavity in both MRI and CT studies. This mucosal thickening shifted sides between examinations in three dogs. Changes appeared most marked on T2-weighted scans. No asymmetric mucosal changes were seen in the mucosa of the ethmoturbinates, vomer-nasal septum, hard palate or the frontal sinuses in any patient on MRI or CT. Computed tomographic contrast enhancement of the thickened mucosa was not statistically significant (P-value < 0.08). In conclusion, the normal nasal cycle may cause asymmetrical mucosal changes in the rostral part of the nasal cavity that mimic MRI and CT characteristics previously reported for inflammatory disease in dogs.

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.

Study of nasal cycles in children by acoustic rhinometry

BACKGROUND

Studies concerning nasal cycle physiology in children are still rare, and controversies exist about its existence. This study was ascertained to evaluate the dynamic behavior of inferior turbinates in children by acoustic rhinometry.

METHODS

Sixteen volunteer patients, aged 2-11 years old (mean, 6.25 years), were evaluated between April and July 2003. The patients submitted to periodic acoustic rhinometry, with triplicate measurements (each 30 minutes) for 3 hours.

RESULTS

All evaluated children presented nasal cycles, with five children presenting a classic pattern (31.25%), three children presenting a concert pattern (18.75%), and eight children presenting an irregular pattern (50%).

CONCLUSION

This study suggests that children present nasal cycles, as well as adults. Nevertheless, the most prevalent pattern in children was the irregular pattern, whereas in adults the most frequently detected is the classic pattern.

Nostril dominance: differences in nasal airflow and preferred handedness

Because there appears to be a general propensity among many people to have a consistency in the sidedness of their lateral preferences, the purpose of the present study was to determine if this consistency extends to the airflow through the individual nostrils as well. To test for this, hot wire anemometers measured the airflow in each nostril at 15-minute intervals for 6 continuous hours in 11 right-handed and 9 left-handed adult males. Participants also provided self-reports of which nostril appeared to have the greater airflow. The airflow measurements supported the hypothesis of a handedness by nostril interaction, in that left-handers more often experienced greater airflow in their left nostrils whereas right-handers showed the opposite pattern. Self-reports were not an especially reliable measure of nasal patency. In most subjects the same nostril was not always the more open one. This left/right shifting of the more patent nostril is termed the nasal cycle. This study also provides the first data comparing the nasal cycle patterns of left-handers and right-handers.

Is the nasal cycle ablated in patients with high spinal cord trauma?

We have observed at our centre that patients with high spinal cord injury frequently complain of nasal obstruction requiring decongestants. This may be due to damage to the cervical sympathetic nerves supplying the nasal mucosa, which ablates the nasal cycle. In this study we assessed the nasal cycle in 10 patients with high spinal cord trauma (above T1 segment) using acoustic rhinometry. We found that all patients assessed within 1 year of injury had nasal obstruction and no nasal cycle. Patients with injuries between 1 and 4 years who complained of a nasal obstruction showed an irregular cycle. Patients with injuries older than 4 years showed a normal alternating reciprocal nasal cycle and an improvement of nasal symptoms. The exact reason for this recovery is presently not clear from this pilot study. Further research will be undertaken to assess reasons for the recovery and possible treatment regimens for this distressing condition.

Atypical nasal challenges in patients with idiopathic rhinitis: more evidence for the existence of allergy in the absence of atopy?

BACKGROUND

The pathophysiology of idiopathic rhinitis is unknown although evidence is accumulating to suggest that many patients may have a localized form of allergic rhinitis in the absence of other atopic symptoms and markers. This study compares detailed nasal challenge results obtained from patients with idiopathic rhinitis to those of atopic and normal controls.

METHODS

Patients with idiopathic rhinitis (n = 23), perennial allergic rhinitis (n = 8) and normal controls (n = 8) underwent a normal saline challenge to exclude hyper-reactivity and then bilateral nasal allergen challenges. Nasal patency was assessed by anterior active rhinomanometry.

RESULTS

All of the patients with atopic rhinitis demonstrated positive bilateral allergen challenges. All normal control subjects had bilateral negative challenges. Two patients in the idiopathic group tested positively to saline and were excluded from further study with 62% of the remainder testing positive to allergens. Of the idiopathic patients testing positive, 85% were sensitive to house dust mite.

CONCLUSION

A significant proportion of patients with idiopathic rhinitis have positive nasal challenges, the vast majority to house dust mite allergen. These findings add to the weight of evidence that suggests 'localized allergy' may exist in the absence of systemic atopic markers.

Combined effects of a nasal dilator and nasal prongs on nasal airflow resistance

STUDY OBJECTIVES

Nasal prongs (NPs), when used to assess nasal flow, can result in dramatic increases in nasal airflow resistance (NR). The aim of this study was to investigate whether the NP-induced increases in NR could be corrected by the simultaneous use of an internal nasal dilator (ND).

DESIGN

NR was estimated by posterior rhinomanometry, in the basal state (NRb), and while breathing with NP (NRp), with ND (NRd), and with both ND and NP (NRd + p).

PARTICIPANTS

The study was performed in 15 healthy subjects.

MEASUREMENTS AND RESULTS

NR (mean NRb [+/- SEM], 2.5 +/- 0.4 cm H(2)O/L/s) significantly decreased with ND (NRd = 1.4 +/- 0.2 cm H(2)O/L/s; p < 0.001) and significantly increased with NP (NRp = 3.8 +/- 0.8 cm H(2)O/L/s; p < 0.001). A significant logarithmic relationship was found between NRd and NRb (r(2) = 0.95; p < 0.0001), and a significant exponential relationship was found between NRp and NRb (r(2) = 0.99; p < 0.0001). While breathing with both ND and NP, NRd + p was significantly lower than NRb (1.9 +/- 1.4 cm H(2)O/L/s; p < 0.02).

CONCLUSIONS

Our results demonstrate that the ND tends to slightly overcorrect the NP-induced increase in NR and suggest that, in view of the possible effects of NPs on upper airway resistance, the combination of both devices might be used for nasal airflow monitoring during nocturnal polysomnography in patients presenting with highly resistive nares.

Reliable and reproducible anterior active rhinomanometry for the assessment of unilateral nasal resistance

Unilateral nasal resistance is now thought to be more important than total resistance in promoting obstructive symptoms. We assessed the reproducibility of anterior active rhinomanometry in measuring unilateral nasal resistance. Ten baseline readings of unilateral nasal resistance were made over a 30-min period in seven healthy subjects (14 nostrils) using anterior active rhinomanometry performed according to the International Committee for the Standardization of Rhinomanometry (ICSR) guidelines. Baseline readings revealed that measurements using anterior active rhinomanometry had an unacceptably high coefficient of variation (19%-60%). With a more time-consuming revised protocol involving multiple recordings and the identification and exclusion of erroneous data, coefficients of variation of 7%-15% were obtained. We conclude that single anterior active rhinomanometry readings are potentially prone to large errors and each researcher using such equipment must satisfy his/herself that their methodology has an acceptable coefficient of variation in their hands. The ICSR guidelines are not always sufficient to allow reproducible measurement and specially designed protocols may be necessary to produce reliable results.

The relationship between particle deposition in the anterior nasal passage and nasal passage characteristics

The objective of this study was to examine the effects of nasal passage characteristics on anterior particle deposition during cyclical breathing. Forty healthy, nonsmoking, adult subjects participated in this study. Nasal passage characteristics such as nostril length, width, angle, ellipticity, and minimum nasal cross-sectional area were measured. The subjects inhaled a polydisperse radioactively tagged aerosol (mass median aerodynamic diameter = 5.4 microns, geometric standard deviation [GSD] = 1.3) into the nose and exhaled through the mouth. The amount of radioactivity in the nose was measured immediately after inhalation and thereafter for 54 minutes. At 52.5 minutes, subjects wiped the accessible portion of the anterior nose to remove any remaining activity. The difference in activity at 52 and 54 minutes was used as a measure of activity removed during the nose wipe. Percentage of activity in the nasal passage at 52 minutes and percentage of activity removed with the nose wipe were considered surrogates for particles deposited in the anterior nasal passage. A multiple regression analysis showed that the degree of ellipticity of the nostrils was significantly related to particle deposition in the anterior nasal passage. These results suggest that ellipticity of the nostrils may be a determinant of the amount of particle deposition in the anterior nasal passage.

Effects of nasal prongs on nasal airflow resistance

STUDY OBJECTIVES

The aim of this study was to investigate whether nasal prongs, which have been proposed to assess nasal flow during sleep, affect nasal airflow resistance (NR).

DESIGN

NR was estimated by posterior rhinomanometry at a 0.5 L/s flow, under eight conditions: in the basal state, and with seven different nasal prongs.

PARTICIPANTS

The study was performed in 17 healthy supine subjects, 8 of whom had basal NR values within the normal range (< or = 2 cm H(2)O.L(-1).s, group 1), and 9 had increased basal NR values (> 2.5 cm H(2)O.L(-1).s, group 2), because of nare narrowness and/or deviated nasal septum.

MEASUREMENTS AND RESULTS

NR increased significantly while breathing with nasal prongs (p < 0.0001 in both groups). The changes in NR (DeltaNR) induced by the different nasal prongs were characterized by large intersubject and intrasubject variability, with a maximum DeltaNR of 24.2 cm H(2)O.L(-1).s. Significant differences were found between the DeltaNR induced by the different nasal prongs (p < 0.001 in group 1, and p < 0.0003 in group 2), and for six of them, DeltaNR was significantly higher in group 1 than in group 2 (p < 0.02).

CONCLUSIONS

This study demonstrates that nasal prongs can markedly increase NR in subjects presenting with nare narrowness and/or deviated nasal septum. Further investigations that would include nocturnal polysomnography are still required to evaluate the possible influence of nasal prongs on the diagnosis of obstructive sleep apnea syndrome and its severity.

Nasal airflow in health and disease

This review examines our present understanding of the physiology, pathophysiology and pharmacology of nasal airflow. The main aim of the review is to discuss the basic scientific and clinical knowledge that is essential for a proper understanding of the usefulness of measurements of nasal airflow in the clinical practice of rhinology. The review concludes with a discussion of the measurement of nasal airflow to assess the efficacy of surgery in the treatment of nasal obstruction. Areas covered by the review include: influence of nasal blood vessels on nasal airflow; nasal valve and control of nasal airflow; autonomic control of nasal airflow; normal nasal airflow; nasal cycle; central control of nasal airflow; effect of changes in posture on nasal airflow; effect of exercise on nasal airflow; effect of hyperventilation and rebreathing on nasal airflow; nasal airflow in animals; cerebral effects of nasal airflow; sensation of nasal airflow; sympathomimetics and sympatholytics; histamine and antihistamines; bradykinin; and corticosteroids.

Combined effects of a mechanical nasal dilator and a topical decongestant on nasal airflow resistance

The goal of this study was to compare the isolated and combined effects of two treatments being used to reduce nasal airflow resistance (NR): an internal nasal mechanical dilator (Nozovent; Prevancure; Sté Pouret, Paris, France) and a topical decongestant, fenoxazoline hydrochloride (Aturgyl; Synthelabo; Le Plessis-Robinson, France). The study was performed in 17 healthy subjects. NR was estimated by active posterior rhinometry at a 0.5 L/s flow under four conditions: in the basal state, with the internal nasal mechanical dilator, after treatment with fenoxazoline hydrochloride, and with both fenoxazoline hydrochloride and the mechanical dilator. The mean NR (+/- SD) decreased from 1.65+/-0.54 cm H2O/L/s in the basal state to 1.02+/-0.27 cm H2O/L/s with the mechanical dilator (p < 0.001), 1.03+/-0.47 cm H2O/L/s with fenoxazoline hydrochloride (p < 0.001), and 0.48+/-0.15 cm H2O/L/s with both the mechanical dilator and fenoxazoline hydrochloride (p < 0.001). The decreases in NR observed after using either the mechanical dilator (deltaNR(N)) or fenoxazoline hydrochloride (deltaNR(A)) were not significantly different. The decrease in NR observed with both (deltaNR(N + A)) was not significantly different from the sum deltaNR(N) + deltaNR(A): 1.16+/-0.53 cm H2O/L/s vs 1.25+/-0.63 cm H2O/L/s, respectively (p > 0.05). deltaNR(N + A) strongly correlated with deltaNR(N) + deltaNR(A): deltaNR(N + A) = 0.80 (deltaNR(N) + deltaNR(A)) + 0.15 (r = 0.96; p < 0.0001). However, the slope of the regression line of deltaNR(N + A) vs deltaNR(N) + deltaNR(A) was significantly lower than unity (p < 0.003). These results demonstrate that, although not totally additive, the effects of using the mechanical dilator and fenoxazoline hydrochloride are cumulative. Further studies that include patients with nasal obstruction would allow us to better evaluate the benefit of a therapy combining both treatments.

Detection of the nasal cycle with acoustic rhinometry: techniques and applications

Acoustic rhinometry is an appropriate method for detecting and recording the nasal cycle in normal subjects in terms of the cross-sectional areas and volume of the nasal cavity. In this study, we tried to detect and to define the nasal cycle in normal subjects so that we might develop a reliable and reproducible technique to be used in conjunction with studies on the physiology and pathology of nasal disease. We used normal volunteer adult subjects and performed bilateral acoustic rhinometry measurements every 15 minutes over 4 hours, along with the use of a visual analog scale for assessment of the subjective feeling of congestion (or patency) just before each acoustic rhinometry measurement. Volume and cross-sectional area changes were observed along with subjective patency-score changes in each subject. The subjective feeling of patency was not related to the volume and cross-sectional area changes measured simultaneously. The technique of recording the nasal cycle with acoustic rhinometry in nasal research is presented.

Studies of spontaneous fluctuations in congestion and nasal mucosal microcirculation and the effects of oxymetazoline using rhinostereometry and micromanipulator guided laser Doppler flowmetry

The mucosa of the inferior turbinate was studied using rhinostereometry and micromanipulator-guided laser Doppler flowmetry in 10 healthy volunteers. First, spontaneous fluctuations were studied measuring congestion and multiple microcirculatory parameters simultaneously every 2 minutes. The subjects were then challenged with oxymetazoline using the same measuring technique studying the effects of the challenge during 12 minutes. There were spontaneous variations in congestion of up to 2.1 mm and variations in perfusion from 38% to 175% of average. There was no correlation between congestion in itself, or change in congestion, to perfusion or any other microcirculatory parameter. After challenge with oxymetazoline there was a rapid decrease in perfusion at 3 minutes after which there were no significant changes. The congestion decreased gradually throughout the procedure. Because congestion reflects the filling of the venous sinusoids and the flowmetry the state of the superficial vessels, we conclude that there are spontaneous short-term fluctuations in the sympathetic tone with independent actions on the different vessels. After challenge with a sympathomimetic drug, there was a decrease in both swelling and flow, but not synchronized. The combination of rhinostereometry and micromanipulator-guided laser Doppler flowmetry is a useful tool to study the dynamics of intranasal challenge reactions.

Effects of different mechanical treatments on nasal resistance assessed by rhinometry

The goal of this study was to compare the effectiveness of three treatments aiming to reduce nasal airflow resistance (NR): an external nasal strip device (Respir+), an internal nasal mechanical dilator (Nozovent), and a topical decongestant (Pernazène). NR was estimated by active posterior rhinometry at both a 0.5 L/s flow (NRF) and a 1 cm H2O pressure (NRP), under four conditions: in the basal state, with Respir+, with Nozovent, and after treatment with Pernazène. The efficacy of each treatment was assessed by the percentage changes in NRF and NRP (%NRF and %NRP, respectively). The study was performed in 15 healthy subjects. The efficacy of the treatments was significantly different, depending on whether it was evaluated by NRF or by NRP (p<0.02), with %NRF and %NRP values, respectively, equal to the following: 88+/-20% and 91+/-14% with Respir+, 58+/-17% and 70+/-13% with Nozovent, and 55+/-29% and 69+/-22% with Pernazène. NRF remained unchanged with Respir+, whereas it significantly decreased with Nozovent and Pernazène (p<0.0001). No significant difference was observed between the effects of the two latter treatments. These results demonstrate that Nozovent, which involves no risk of side effects or drug interactions, is an effective treatment to improve nasal breathing. Nozovent might therefore be recommended as an alternative to topical decongestants, for certain subjects presenting with nasal obstruction.

Correlation between nasal obstruction symptoms and objective parameters of acoustic rhinometry and rhinomanometry

Acoustic rhinometry and rhinomanometry have been used to assess nasal airway patency objectively. We compared nasal obstruction symptoms before and after decongestion with several parameters of these objective tests. The patients assessed their nasal obstruction using a visual analogue scale (VAS). Cross-sectional areas and nasal resistance were measured by acoustic rhinometry and rhinomanometry before and after topical application of 1% phenylephrine solution in 32 patients with nasal obstruction symptoms. There was no significant correlation between the difference in the VAS and the difference in nasal resistance. There was also no significant correlation between the difference in the VAS and minimal cross-sectional area and cross-sectional areas at 3.3 cm (CA3.3), CA4.0 and CA6.4 from the nosepiece both in the wide and narrow sides and in both nasal cavities before and after nasal decongestion. It is concluded that rhinomanometry and acoustic rhinometry may have no diagnostic value in estimating the severity of nasal obstruction symptoms.

Physiological versus pharmacological decongestion of the nose in healthy human subjects

In the present study we were interested to determine whether the maximum unilateral nasal airflow associated with the nasal cycle (Fmax physiol) was equivalent to the maximum unilateral nasal airflow that could be achieved by the application of a topical nasal decongestant (Fmax pharmacol). Eight healthy subjects (three male and five female, aged between 19-28 years) were recruited for this study. Unilateral nasal airflow was measured using posterior rhinomanometry at the inspiratory reference pressure of 75 Pa by alternately occluding each nostril with surgical tape. The study was run over 2 consecutive days. On day one, measurements of unilateral nasal airflow were performed every hour for 8 h in each subject and Fmax physiol was found to be 265 cm3/sec (147) (median and interquartile range). On day 2 the median unilateral nasal airflow before application of the nasal decongestant was 171 cm3/sec (140) and this increased to 251 cm3/sec (127) (p = 0.046) at 15 min and to 278 cm3/sec (134) (p = 0.005) at 45 min after application of the decongestant (Fmax pharmacol). A paired comparison of Fmax physiol and Fmax pharmacol showed that these nasal airflow measurements were not significantly different (p > 0.999). The results show that there was no difference between the maximum physiological decongestion produced during the course of the nasal cycle and that produced pharmacologically by a topical nasal decongestant. This indicates that the point of maximal sympathetic vasoconstrictor tone occurring during the nasal cycle causes a constriction of the nasal venous sinuses that is equal to the constrictor response that can be achieved by applying a topical sympathomimetic medication.

Spontaneous changes of unilateral nasal airflow in man. A re-examination of the 'nasal cycle'

It is now over 100 years since Kayser (Archiv für Laryngol Rhinol 1895; 3: 101-120) first reported in the scientific literature that the human nasal passages exhibit spontaneous changes in unilateral nasal airway resistance, yet our understanding of this unusual phenomenon is still very confused. Spontaneous, reciprocal changes in unilateral nasal resistance are often referred to as a "nasal cycle" and although this term is now commonly used to describe spontaneous changes in nasal resistance in man and animals, there is little evidence for any true periodicity. A major problem in increasing our knowledge and understanding of the so-called "nasal cycle" is that most studies have relied on simple descriptions of the changes in nasal resistance and have not developed any numerical parameters to quantify the changes in resistance over time. This lack of definition of what actually constitutes a nasal cycle has meant that the literature of the present day generally accepts the views put forward by Heetderks (Am J Med Sci 1927; 174; 231-244) and Stoksted (Acta Otolaryngol (Stockh) 1953; Suppl 109: 159-175) that around 80% of the healthy population exhibit a regular cycle. In order to define the characteristics of the spontaneous changes in nasal airway resistance we have used numerical measures of reciprocity and also developed a measurement of the division of airflow between the nasal passages over time. With these two parameters it is possible to describe the nature of the spontaneous changes in airflow in numerical terms and to define what exactly constitutes a nasal cycle. Fifty-two volunteers underwent hourly measurement of unilateral nasal airflow for 8 h. For each volunteer, two values were derived from the graph of unilateral nasal airflows against time; the correlation coefficient between unilateral airflows (r) and the airflow distribution ratio between the two nasal airways (ADR). The spread of different types of airflow pattern (nasal cycle) throughout the population was illustrated by plotting r against ADR for each subject. A nasal cycle was defined as having an r value between -0.6 and -1.0, and an ADR value between 0.7 and 1.0. Only 21% (11 of the 52 volunteers) exhibited airflow patterns that could be defined as a nasal cycle in these terms. This finding contradicts the generally accepted, but undefined, view that around 80% of the population exhibit a regular nasal cycle. The numerical definition of a nasal cycle in terms of both reciprocity and airflow distribution, as described in this paper may help to clarify our understanding of this interesting phenomenon and allow rhinologists to describe the spontaneous changes in nasal airflow in more exact terms than have been used previously in the literature.

Influence of age on the 'nasal cycle'

The nasal cycle is classicially defined as a side-to-side fluctuation in nasal engorgement and airflow, with period lengths ranging from approximately 1 to 5 hours. This cycle, as well as its variants (e.g., cyclic changes on one side of the nose only), is produced by alterations in autonomic tone of the nasal vasculature and reportedly correlates with a number of ultradian rhythms, including asymmetries in left:right cerebral electroencephalographic (EEG) activity and differential performance on visual/spatial psychological tasks. Since the pacemaker for the nasal cycle is believed to lie within the suprachiasmatic nucleus of the hypothalamus, and this nucleus evidences degeneration in later life, we sought to determine whether the nasal cycle or its variants changes with age. To achieve this end, we used a liquid crystal thermography exhalation monitor to measure relative airflow of the two nasal chambers at 15-minute intervals for 6 hours in 60 people representing four age categories: 18 to 29 years (n=12); 30 to 49 years (n=15); 50 to 69 years (n=13); and 70 to 85 years (n=20). Overall, the proportion of subjects exhibiting the alternating rhythmicity associated with the classic nasal cycle decreased with age. No association was present between nasal cycle parameters and scores on the Mini-Mental State Examination (MMSE). The results suggest that the classic nasal cycle may be a marker for age-related central nervous system changes.

Asymmetry in the nasal mucociliary transport rate

Several methods have been devised for measuring the nasal mucociliary transport rate (N-MTR), but only one side of the nose has usually been studied. This study was conducted to determine whether there are side-to-side differences in N-MTR. A radioisotopic method was used to investigate 185 patients with various respiratory symptoms. Bilateral measurements were performed in the 111 patients with an N-MTR of under 7 mm per minute. In 16 healthy control subjects, the N-MTR ranged from 5.0 to 14.6 mm per minute (mean: 7.8 mm per minute) in the better nostril and from 1.2 to 11.0 mm per minute (4.3 mm per minute) in the poorer nostril (P<.001). In the 111 patients, the N-MTR ranged from 0.0 to 12.0 mm per minute (3.5 mm per minute) in the better nostril and from 0.0 to 9.5 mm per minute (1.7 mm per minute) in the poorer nostril (P<.001). In the control subjects, the mean N-MTR was better (P=.011) in the decongested nostril. Even when the N-MTR was less than 5 mm per minute on the first measured side, it was normal on the opposite side in 18.9% of patients and in 18.8% of control subjects. The author concluded that if the N-MTR is impaired in one nostril, it should also be measured in the opposite nostril.

Changes in the amplitude of the nasal cycle associated with symptoms of acute upper respiratory tract infection

Nasal airflow is normally asymmetrical and subject to spontaneous reciprocal changes which are often referred to as the 'nasal cycle'. The nature of these spontaneous changes in nasal resistance is poorly understood and little information is available about how they are affected by nasal disease. In order to understand the changes in nasal resistance in health and disease it is important to record unilateral resistance rather than express results as total nasal resistance. Unilateral resistance is subject to continuous reciprocal changes and therefore new measurements were developed in this study in order to quantify the nasal resistance of each nasal passage. Twelve human subjects (age 19-38) with symptoms of acute respiratory tract infection (URTI) were recruited for the study which involved serial measurements of unilateral nasal airway resistance using the technique of posterior rhinomanometry over a period of six hours. Measurements were made on one day when subjects had symptoms of URTI and then repeated 6-8 weeks later when subjects were healthy. The results of this study show that all of the subjects exhibited spontaneous reciprocal changes in nasal airway resistance on both study days but that there was a significant increase in the amplitude of the changes in resistance when the subjects had symptoms of URTI with one nasal passage often becoming severely congested. In order to quantify the amplitude of the reciprocal changes in nasal resistance two new measures were used. The minimum and maximum nasal airway resistance recorded for each nasal passage during the six hour recording period (MIN NAR and MAX NAR). Mean MIN NAR with URTI was 0.4 Pa cm3s +/- 0.07 which was not significantly different from mean MIN NAR in health which was 0.36 Pa cm3s +/- 0.05 (p = 0.22, n = 20). The mean MAX NAR during URTI was 2.44 Pa cm3s +/- 0.38 and this decreased significantly to 1.36 +/- 0.17 when recorded during healthy conditions (p = 0.01, n = 20). The increased amplitude of spontaneous reciprocal changes in nasal airway resistance associated with symptoms of URTI is proposed to be due to an increased filling pressure to the nasal venous sinusoids associated with a nasal inflammatory response. A model is proposed to explain the role of the nasal sympathetic vasoconstrictor tone and nasal venous filling pressure in the control of nasal airway resistance and to help explain the periods of unilateral nasal obstruction often associated with allergic and infective rhinitis.

A chaotic systems analysis of the nasal cycle

The nasal cycle is a chaotic ultradian rhythm with a period ranging from about 75 to 200 minutes. It has been shown to correlate highly with EEG amplitude in the contralateral hemisphere at virtually all frequencies, suggesting a connection between this rhythm and laterality of brain function. During a three-week period, five participants estimated airflow from both nostrils every 30 minutes during waking hours. Estimates were recorded on Likert scales and analyzed in three distinct phases: (1) reconstructing two-dimensional attractors by lagging and embedding; (2) computing Fourier frequency analyses; and (3) estimating fractal dimensions. Attractor reconstructions demonstrate noticeable order when compared to Monte Carlo reconstructions of the same data sets, and dimension estimates are in the fractal range. The attractor reconstructions, in combination with the frequency analyses, show distinct individual differences in the structure of the nasal cycle. The advantages of chaotic systems analyses over traditional behavioral statistics are discussed.

The nasal cycle after deprivation of airflow: a study of laryngectomy patients using acoustic rhinometry

Previous studies of the nasal cycle in laryngectomy patients using rhinomanometric techniques concluded that the cycle was abolished as a result of the cessation of airflow after laryngectomy. This study was performed with 20 postoperative laryngectomy patients (mean time after surgery 4 years, range: 2 weeks to 10 years) and 10 control subjects matched for age and sex (including 2 preoperative patients). Acoustic rhinometry was used to determine minimum nasal cross-sectional area and nasal cavity volume as the indices of nasal patency. Testing was repeated at intervals of 15-30 min over a period of 3-8 h. Fluctuations in nasal patency were observed in all laryngectomees and controls. The fluctuations were classified as 'classical' (reciprocal alternating) in 5 (25%) laryngectomees and 5 (50%) controls. An 'irregular' pattern of fluctuation was seen in 8 (40%) laryngectomees and 2 (20%) controls. An 'in concert' cyclical pattern was seen in 7 (35%) laryngectomees and 3 (30%) controls. This is the first demonstration of retention of the nasal cycle after airflow deprivation. Whilst the cycle may in some instances be modified after operation, it is not abolished. The central generation of the cycle is confirmed, although afferent input from airflow receptors may play a role in modulating the cycle's pattern and amplitude.

The relationship of cortical activation to alternating autonomic activity

It has been proposed that it is possible to selectively activate the cerebral hemispheres, thereby enhancing lateralized cognitive abilities. A proposed method of achieving selective activation is by altering nasal congestion/decongestion (nasal cycle), which is believed to effect a contralateral change in hemispheric activation through the autonomic nervous system (ANS). This hypothesis was tested in 4 right-handed male and 6 right-handed female undergraduate students. Subjects were untrained in specific breathing techniques but were aware of the experimental hypothesis. Four 1 min samples of EEG were recorded in each of 4 experimental conditions in which nasal decongestion was altered by having subjects lie in the lateral recumbent position and occluding the contralateral nare. Cortical activation and laterality were examined using ratios of the low beta (12-18 Hz) and high alpha (10-12 Hz) bandwidths relative to each other and between hemispheres. Repeated measures ANOVAs showed non-significant changes in the alpha and beta bandwidths across the 4 experimental conditions. Although changes in hemispheric activation have been postulated for all subjects, this study does not support such changes in subjects untrained in breathing techniques.

Changes in nasal mucosal blood flux and air-flow resistance on unilateral histamine challenge

To investigate reflex vascular control in the nose, we challenged each side of the nose with 0.9% saline and histamine (0.3 mg aqueous) and observed changes in unilateral nasal airway resistance (Rnaw) and laser doppler flux (LDF) in response to contra-lateral and ipsilateral challenge in eight normal subjects. Preliminary studies demonstrated that the preferred site for observation of LDF was the nasal septum (same-day concordance 0.920; inferior turbinate 0.307). Ipsilateral contra-lateral saline induced no significant change to either parameter. Ipsilateral histamine produced a highly significant rise in LDF (757 arbitrary units SEM 94 at 3 min; baseline 489 SEM 75: P < 0.05) and Rnaw (baseline: 3.10, SEM 0.52; 5 min: 8.81, SEM 2.09 cmH2O/l/s: P < 0.01). Contra-lateral histamine produced a significant P < 0.05) fall in both (LDF 317, SEM 24 at 3 min; Rnaw 2.67, SEM 0.78 cm H2O/l/s at 6 min). This previously unrecorded observation suggests a neural reflex that increases the patency of the contra-lateral nostril after unilateral obstruction is provoked.

The nasal cycle in patients with autonomic nervous disturbance

The nasal cycle is thought to be controlled by the autonomic nervous system. In this study, we measured nasal airflow resistance in patients with lesions of the autonomic nerves that supply the nasal mucosa. We examined 20 patients with facial palsy as examples of parasympathetic disturbance, five with Horner's syndrome as examples of sympathetic disturbance, and one with acute pandysautonomia. The nasal cycle was observed in 13 patients with facial palsy and four patients with Horner's syndrome. The nasal cycle was also observed in one patient with acute pandysautonomia and disturbance of the sympathetic-parasympathetic nerves. Our results indicate that disturbance of the parasympathetic and sympathetic nerves has little influence on the nasal cycle.

Distribution of eosinophils in the nose in patients with perennial rhinitis

The traditional method of classifying perennial rhinitis into eosinophilic and non-eosinophilic is by taking a single nasal smear from one nostril. In the light of personal experience it was felt that this method of sampling may be inadequate. The present study included 20 patients with perennial rhinitis undergoing nasal surgery. Serum total IgE levels were taken and those above 40 IU/ml had allergen specific IgE measured. Nasal smears and biopsies were taken from 5 sites on each side of the nose; middle and inferior turbinates and post nasal space. The smears significantly correlated with the biopsies (rs = 0.446, P < 0.001). The distribution of eosinophils between and within nasal cavities was found to differ. Representative sampling of the nose is important for accurate eosinophil expression. The definition of an eosinophil rich and poor nose requires greater clarification as it has great clinical relevance regarding management.

Developmental changes in nasal airflow patterns

Airflow through each nasal passage was measured every 10 min throughout a 5-h period in 48 subjects whose ages ranged from 3 to 17 years. The data were subjected to statistical techniques that characterize and quantify periodicities in a time series. Such analyses revealed that for the majority of children younger than 7 years of age, the airflow through the two nostrils changed either randomly (50%) or in parallel (31%). Between the ages of 7 and 10 years, however, the distribution of airflow patterns characteristic of adults emerged, such that the incidence of reciprocity increased to 63%, and the incidence of random and parallel patterns decreased to 31% and 6%, respectively. A similar distribution was evidenced in the 11- to 17-year-old subjects (56% reciprocal, 38% random, 6% parallel). Although the total airflow through the nose also increased with age, the increased inspiratory flow rates could not account for the developmental changes evidenced in airflow patterns.

The management of neonatal rhinitis

Life-threatening upper airway obstruction secondary to neonatal rhinitis is a rare and poorly understood condition. Despite potential lethal effects, there has been no basic scientific research investigating the nature of this curious condition. This paper retrospectively reviews 8 patients suffering from neonatal rhinitis. Both the medical and surgical management of neonatal rhinitis and possible aetiological factors involved are discussed. Increasing clinical awareness of this condition may, therefore, serve as inspiration for future research of both an epidemiological and basic scientific nature.

Modifications of the nasal cycle in patients with hypothalamic disorders: Kallmann's syndrome

The nasal cycle is a phenomenon characterized by cyclic changes in the airflow resistance of each nasal fossa from congestion or constriction of the nasal erectile tissue. This phenomenon is caused by alterations in the influence exerted by the autonomic nervous system and is believed to be regulated by a hypothalamic center. In order to verify this hypothesis on the hypothalamic regulation of the nasal cycle, the authors studied a group of subjects with Kallmann's syndrome. This disorder is characterized by coexisting hypothalamic hypogonadism and hyposmia or anosmia due to hypothalamic and olfactory center hypoplasia. An anomalous nasal cycle was found in all the subjects with Kallmann's syndrome. This disorder might be related to hypothalamus atrophy.

The objective assessment of nasal patency

Nasal patency was measured by five techniques in 24 subjects and the results compared. In addition three pulmonary parameters were measured as well as height and weight. Nasal resistance to airflow measured by active anterior rhinomanometry was found to be highly correlated with peak nasal inspiratory flow rate. Other correlations were also noted. Peak nasal inspiratory flow was itself highly correlated with pulmonary peak expiratory flow rate as well as with several other parameters. The possible reasons for these correlations are discussed in terms of fluid mechanics.

Paranasal sinus imaging

The inability of plain radiographs to yield conclusive information about the ostiomeatal complex in sinusitis is no longer a significant problem. Computed tomography (CT), magnetic resonance imaging (MRI), and improved endoscopic technology now enable almost complete exploration of the sinus anatomy and the pathophysiology of sinus disease. Nasal endoscopy provides a clear view of the anterior nasal cavity--including the middle meatus--in patients with symptoms of sinusitis. However, the maxillary ostia are still difficult to visualize directly. CT is required for noninvasive evaluation of deep ostiomeatal air passages and posterior ethmoid and sphenoid sinuses. MRI of the nasal cavity and paranasal sinuses, although of limited use for displaying nasal morphology, is even more sensitive than CT in identifying fungal concretions and neoplasms.

Nasal airflow in inspiration and expiration

Inspiratory and expiratory airflow rates were measured in 30 subjects during quiet respiration (at a pressure gradient of 150 Pa) and at peak flow rates. For low flow rates airflow rate was greater for inspiration than for expiration. Conversely at peak flow rates flow was greatest during expiration. Thus there was a reversal in the phase relationship between inspiration and expiration as flow rate increased. It was also found that peak inspiratory flow rate correlated better with values for nasal resistance than did peak expiratory flow rate. Flow rate measured by rhinomanometry during quiet respiration was more sensitive to physiologically induced changes in nasal resistance than was peak flow rate. The findings are discussed with reference to previous work on the physiology of nasal airflow.

Evaluation of the effect of localized skin cooling on nasal airway volume by acoustic rhinometry

Ten healthy subjects (four men and six women) were subjected to localized skin cooling by submersion for 5 min of both feet and, in another experiment, one hand and forearm into ice-cold water. Repeated measurements of nasal cavity volumes by a new method, acoustic rhinometry, showed characteristic patterns ranging from marked increases in volumes lasting the entire exposure period to transient monophasic or biphasic responses to no change at all. The pattern in individual subjects was reproducible with the two methods of cooling, and it could be characterized by five types when related to baseline measurements during the preexposure period. Because of large minute-to-minute variations, probably determined by local differences and fluctuations in blood flow in tissues through the nose, evaluation of induced changes in the nasal cavity volume cannot be based on single measurements as has frequently been done in the past by using rhinomanometry as the experimental method. The mechanisms behind the characteristic patterns in immediate human nasal response to local skin cooling challenge remains to be explored.

Rhinomanometry evaluation of the effects of pre- and post-operative SMR on exercise

Nasal airway resistance due to uncomplicated DNS was examined in 43 patients, and the results compared with those obtained following corrective surgery. The patients were examined independently by the two authors using a strict examination protocol. Rhinomanometry was carried out pre- and post-operatively at rest and after exercise assessing the worst and the better breathing nostrils separately. The results show that both resting and post-exercise nasal resistance was reduced following septal surgery.

Nasal mucosal temperature and the effect of acute infective rhinitis

Nasal mucosal temperature was measured in 71 healthy subjects with an electronic thermometer. No correlation was found between the nasal mucosal temperature and age or sex. An increased mucosal temperature was found in patients with acute rhinitis, an effect which is supposed to assist in the defence system against microorganisms. When measuring nasal mucosal temperature over a 7-h period at the same time as nasal airway resistance, there was no correlation between these factors, indicating that the temperature is independent of the state of the capacitance vessels.

Clinical nasal obstruction and objective respiratory mode determination

Nasal obstruction represents a considerable portion of the symptoms addressed by the otolaryngologist. It has received widespread interest in the orthodontic literature as well, because of the presumed relation between nasal obstruction and facial growth, especially vertical maxillary excess. The range of normal variation in oral versus nasal breathing has not been defined. This study attempted to correlate patient symptoms with respiratory mode. A sample of 20 symptomatic adult subjects presenting with nasal obstruction was compared to a control sample of 20 asymptomatic adults by means of SNORT (Simultaneous Nasal and Oral Respirometric Technique). Nasal resistance was significantly different between the two groups, but percent nasality (that proportion of the total volume of air breathed nasally) was a more consistent and significant finding. The relevance of these results to both clinical and basic physiology is discussed.