Posture and nasal patency: evaluation by acoustic rhinometry

Polysomnographic Assessment on Osahs Outcomes in Patients with Nasal Obstruction Undergoing Septoplasty with Partial Inferior Turbinectomy

The relationship between nasal obstruction and obstructive sleep apnea has raised interest among otolaryngologists since years. There are studies that suggest that surgical correction of nasal obstruction improves sleep quality and reduces symptoms of sleep apnea. This lead to our study to understand the effect of nasal surgery on obstructive sleep apnea hypopnea syndrome (OSAHS).

AIM

To assess the effect of nasal surgery in improvement in Obstructive Sleep Apnoea Hypopnoea Syndrome in patients with nasal obstruction by Polysomnography (PSG).

MATERIAL AND METHODS

This study included 30 patients with nasal obstruction who underwent septoplasty and/or turbinate reduction procedure with pre and post operative assessment of respiratory distress index (RDI) including apnoea hypopnoea index (AHI), obstructive apnoea index (OAI), Snoring Index (SI) using polysomnography (PSG).

RESULT

Nasal correction surgery showed statistically significant improvement (p-value < 0.001) in RDI from 13.66 to 6.66, OAI from 6.34 to 3.18 and Snoring Index from 161.77 to 62.23 as assessed by polysomnography. There was statistically significant improvement in minimal saturation levels (during sleep) and positional sleep apnoea.

CONCLUSION

Isolated nasal surgery like septoplasty and/or turbinate reduction improved sleep parameters and alleviated OSA symptoms in patients with static nasal obstruction and obstructive sleep apnoea/hypopnoea syndrome. However, patients with multilevel or dynamic airway obstruction may need further intervention.

Reduction of postural nasal resistance following oropharyngeal surgery in patients with moderate-severe obstructive sleep apnea

BACKGROUND

Patients with obstructive sleep apnea (OSA) have elevated nasopharyngeal resistances due to increased turbulent airflow. The study aims to investigate the effect of oropharyngeal surgery on nasal resistance in patients with various severity levels of OSA.

METHODOLOGY

Patients with greater or equal to 5 events hourly on the apnea-hypopnea index (AHI) were enrolled. Patients with retropalatal obstruction underwent uvulopalatopharyngoplasty, while patients with concurrent retrolingual obstruction under- went uvulopalatopharyngoplasty (UPPP) plus tongue base suspension. Before surgery and after surgery, subjective outcomes were assessed using a visual analog scale (VAS), and objective outcomes were assessed using overnight polysomnography and rhinomanometry. The limitation of the study was that UPPP instead of expansion sphincter pharyngoplasty was performed in this study.

RESULTS

Sixty-two patients were enrolled, while 30 patients were diagnosed as mild OSA (group Mild) and 32 patients were mo- derate-severe OSA (group MS). The preoperative VAS of nasal obstruction in recumbency during sleep was significantly reduced after surgery in group MS. However, no significant differences between preoperative and postoperative VAS were found in group Mild. The postoperative anterior and posterior total nasal resistances (TNR) in sitting and supine positions were not significantly different from those before surgery in group. In contrast, the postoperative posterior TNR in supine position was 0.292±0.301(Pa/ cm3/s), compared with 0.425±0.343(Pa/cm3/s) preoperatively.

CONCLUSIONS

Oropharyngeal surgery improves nasal obstruction during sleep and lowers the supine TNR measured in poste- rior rhinomanometry in patients with moderate-severe OSA. Oropharyngeal surgery is a possible treatment for postural nasal obstruction in patients with moderate-severe OSA.

In silico approaches to respiratory nasal flows: A review

The engineering discipline of in silico fluid dynamics delivers quantitative information on airflow behaviour in the nasal regions with unprecedented detail, often beyond the reach of traditional experiments. The ability to provide visualisation and analysis of flow properties such as velocity and pressure fields, as well as wall shear stress, dynamically during the respiratory cycle may give significant insight to clinicians. Yet, there remains ongoing challenges to advance the state-of-the-art further, including for example the lack of comprehensive CFD modelling on varied cohorts of patients. The present article embodies a review of previous and current in silico approaches to simulating nasal airflows. The review discusses specific modelling techniques required to accommodate physiologically- and clinically-relevant findings. It also provides a critical summary of the reported results in the literature followed by an outlook on the challenges and topics anticipated to drive research into the future.

Establishing a Patent Nasal Passage in Obstructive Sleep Apnea

The role of the nose in the pathophysiology and treatment of sleep-disordered breathing (SDB) has not been fully understood and might have been underestimated. In the Staring resistor model, the nose is regarded as a passive and noncollapsible tube, but recent studies have shown that the nose might participate more in the pathophysiology of SDB as anatomic, neuromuscular, and respiratory factors than previously reported, which might imply the nose is an active noncollapsible tube. The roles of nasal treatments for OSA are not only the reduction of AHI, but also the improvement of subjective symptoms, sleep quality, and CPAP adherence.

Reproducibility of Acoustic Rhinometric Measurements

The purpose of this study is to evaluate the reproducibility of acoustic rhinometric measurements obtained by means of a technique that avoids distortion of the compliant nasal vestibule. Subjects with noses untreated by decongestant were tested every minute for 6 consecutive minutes (576 area-distance curves–A-D curves), every 30 minutes for 6 consecutive hours (672 A-D curves), every day at 9 AM for 5 consecutive days (1200 A-D curves) and every Monday morning for 5 consecutive weeks (1200 A-D curves). The coefficient of variation found for the total minimum cross-sectional area (MCA) and total nasal volume (NV) increased with duration of the time interval between test and retest from 5% to 17% and from 4% to 9%, respectively. Variation of total MCA (combined right and left) and total NV (combined right and left) was smaller than variation of unilateral MCA or NV. Despite the dynamic nature of the nose, a standardized acoustic rhinometric technique can obtain acceptable results from subjects acting as their own controls in nasal physiological research and in clinical assessments.

Nasal Airway Volumetric Measurement Using Segmented HRCT Images and Acoustic Rhinometry

Semiautomatic segmentation methods using High Resolution Computed Tomography (HRCT) or Magnetic Resonance Imaging give accurate and reproducible volumetric measurements in various intracranial diseases. In this prospective study, for the first time in literature, with the help of a new semiautomatic segmentation technique and coronal HRCT, we correlated the volumes and cross-sectional areas of the nasal cavity with those obtained by clinical acoustic rhinometry in 14 patients with chronic sinusitis. The measurements obtained by both techniques showed statistically significant correlations between volumes in the anterior and middle parts, but statistically poor correlations between the volumes in the posterior part of the nasal cavity. Coronal HRCT and our new microcomputer applicable semiautomatic segmentation software proved compatible with daily clinical practice. Based on the promising results of our study, we recommend the use of this technique in the validation studies of acoustic rhinometry and in complicated cases as a complementary examination in the evaluation of nasal cavity.

Acoustic impedance rhinometry (AIR): a technique for monitoring dynamic changes in nasal congestion

We describe a simple and inexpensive method for monitoring nasal air flow resistance using measurement of the small-signal acoustic input impedance of the nasal passage, similar to the audiological measurement of ear drum compliance with acoustic tympanometry. The method requires generation of a fixed sinusoidal volume-velocity stimulus using ear-bud speakers, and an electret microphone to monitor the resultant pressure fluctuation in the nasal passage. Both are coupled to the nose via high impedance silastic tubing and a small plastic nose insert. The acoustic impedance is monitored in real-time using a laptop soundcard and custom-written software developed in LabView 7.0 (National Instruments). The compact, lightweight equipment and fast time resolution lends the technique to research into the small and rapid reflexive changes in nasal resistance caused by environmental and local neurological influences. The acoustic impedance rhinometry technique has the potential to be developed for use in a clinical setting, where the need exists for a simple and inexpensive objective nasal resistance measurement technique.

Changes in nasal volume after surgically assisted bone-borne rapid maxillary expansion

INTRODUCTION

The purposes of this study were to detect, locate, and examine the changes in transverse nasal width, area, and volume from bone-borne, surgically assisted rapid maxillary expansion (SARME) with the Dresden distractor by using computer tomography (CT).

METHODS

Sixteen patients (average age, 28.7 years) underwent axial CT scanning before and 6 months after SARME. They also underwent CT fusion on specific bony structures. The nasal bone width was examined in the coronal plane. The cross-sectional images of the nasal cavity were taken of the area surrounding the apertura piriformis, the choanae, and in between. We calculated cross-sectional areas and nasal volume according to these data.

RESULTS

All but 2 patients had an increase in nasal volume of at least 5.1% (SD, 4.6%). The largest value of 35.3% (SD, 45.8%) was measured anteriorly on the nasal floor, decreasing cranially and posteriorly. This correlated with the V-shaped opening of the sutura palatina. There was no significant correlation between increase in nasal volume and transversal expansion.

CONCLUSIONS

Because most of the air we breathe passes over the lower nasal floor, SARME is likely to improve nasal breathing.

CT analysis of nasal volume changes after surgically-assisted rapid maxillary expansion

OBJECTIVE

Aim of this study was to detect the changes in nasal volume due to bone-borne, surgically-assisted rapid palatal expansion (RPE) with the Dresden Distractor using computed tomography (CT).

MATERIALS AND METHODS

17 patients (mean age 28.8) underwent axial CT scanning before and 6 months after RPE. The nasal bone width was examined in the coronal plane. Cross-sectional images of the nasal cavity were taken of the area surrounding the piriform aperture, choanae and in between. Bony nasal volume was computed by connecting the three cross-sectional areas.

RESULTS

All but two patients showed a 4.8% increase in nasal volume (SD 4.6%). The highest value, 33.3% (SD 45.1%), was measured anteriorly at the level of the nasal floor. This correlated with the midpalatal suture's V-shaped opening. There was no significant correlation between an increase in nasal volume and transverse dental arch expansion.

CONCLUSION

As most of the air we breathe passes the lower nasal floor, an improvement in nasal breathing is likely.

REM-associated nasal obstruction: a study with acoustic rhinometry during sleep

OBJECTIVE

Obstructive sleep apnea events are more common in REM sleep, although there is no relationship between sleep phase and pharyngeal airway status. We studied the patency of the nasal airway during REM and non-REM sleep with the use of acoustic rhinometry.

METHODS

Serial acoustic rhinometric assessment of nasal cross-sectional area was performed in 10 subjects, before sleep and during REM and non-REM sleep. All measurements were standardized to a decongested baseline with mean congestion factor (MCF).

RESULTS

MCF in the seated position was 10.6% (+/-3.7) and increased with supine positioning to 16.2% (+/-2.3). In REM sleep, MCF was highest, at 22.3% (+/-1.7). In non-REM sleep, MCF was lowest, at 2.3% (+/-3.1). All interstage comparisons were statistically significant on repeated measures ANOVA (P < 0.05).

CONCLUSION

REM sleep is characterized by significant nasal congestion; non-REM sleep, by profound decongestion. This phenomenon may be attributable to REM-dependent variation in cerebral blood flow that affects nasal congestion via the internal carotid system. REM-induced nasal congestion, an indirect effect of augmented cerebral perfusion, may contribute to the higher frequency of obstructive events in REM sleep.

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.

[Diagnostic methods of nasal respiratory function]

Objective assessment of nasal obstruction may help with preoperative planning for rhinosurgery and indicate different aspects of endonasal pathology. To improve quality control, preoperative and postoperative objective assessment is desirable. This review presents objective functional diagnostic tools and explains their appropriate uses, the information obtained, and their limitations. An algorithm is presented for analysing nasal obstruction by means of objective functional assessment. Examples illustrate how to use this information for preoperative planning in rhinosurgery.

Body Position-Dependent Shift in Odor Percept Present Only for Perithreshold Odors

We recently demonstrated that a supine position causes a decrease in olfactory sensitivity compared with an upright position. We pursued that initial finding in 3 separate experiments in which we explored the extent of, and mechanism underlying, this phenomenon. In Experiment 1, we replicated the decrease in olfactory sensitivity when in a supine compared with an upright position. In Experiment 2, we measured body position-dependent shifts in physiological variables and sniff measures while smelling suprathreshold odorants and performing a perithreshold odor intensity discrimination task. Olfactory performances were reduced while supine. However, no relationships between the shift in olfactory performances and either the physiological variables or sniff measures were found. In Experiment 3, we determined that there were no position-dependent shifts in ability to discriminate or identify suprathreshold odors or rate them for pleasantness, intensity, or familiarity. However, a drop in scores was observed, and performance was slowed, on a cognitive skill while supine. These results demonstrate a body position-dependent shift in olfactory sensitivity only for perithreshold odors that appears to be mediated by cognitive rather than physiological factors. Implications for olfactory imaging studies are discussed.

Physiological change in nasal patency in response to changes in posture, temperature, and humidity measured by acoustic rhinometry

BACKGROUND

Acoustic rhinometry has been used to assess nasal patency and to calculate nasal cavity volume. This study used acoustic rhinometry to assess changes in nasal patency after alterations in posture, unilateral mechanical obstruction, temperature, and humidity.

METHODS

Eight healthy adult volunteer subjects underwent acoustic rhinometry during the following conditions: (1) sitting position (control), (2) supine position, (3) left lateral recumbent position, (4) nostril unilaterally mechanically blocked, (5) ice pack on neck, (6) drinking cold water, (7) drinking hot water, (8) nasal nebulizer, and (9) oxymetazoline decongestant.

RESULTS

Two distinct patterns emerged based on the total nasal cavity volumes in response to the decongestant. Subjects with initial unilateral nasal cavity volumes near the mean had an expected increase in total volume after the topical decongestant administration. There were two subjects with initial volumes of 1 SD above the mean that had a paradoxical decrease in total volume in response to the decongestant. In all subjects, there was a significant decrease in the volume of each of the nasal cavities in response to ingestion of hot water at 1 minute. There was a significant decrease in the volume of the smaller of the two nasal cavities in response to nebulizer treatment and hot water ingestion at 5 minutes. Total nasal cavity volume changes were not significant for any of the variables.

CONCLUSION

Changes in nasal cavity volumes were detected by acoustic rhinometry after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. Nebulizer treatment and hot water ingestion caused a significant decrease in nasal volume. The nose of a healthy patient was able to adapt to environmental and physiological changes to maintain a consistent total nasal volume within 15 minutes.

Nasal patency measured by acoustic rhinometry in East Asian patients with sleep-disordered breathing

BACKGROUND

Nasal obstruction is thought to be a risk factor in obstructive sleep apnea (OSA). However, the relationship between nasal patency and sleep-disordered breathing remains controversial. The aim of this study was to examine the association between acoustic rhinometry findings and results of overnight polysomnography.

METHODS

From February to October 2003, patients who underwent overnight polysomnography assessment were enrolled in the study. We excluded patients who were under 20 years old, had severe deviated nasal septum, had previously received nasal or palatal surgery, or could not complete sleep test or acoustic rhinometry examination. Participants' basic data including age, gender, neck circumference, and body mass index (BMI) were collected. All participants received acoustic rhinometry before overnight polysomnography. The results along with sleep-test outcomes were recorded and analyzed.

RESULTS

A total of 87 patients were included in this study. Patients with respiratory disturbance index (RDI) less than 5/h (n = 26) or with RDI of 5-30/h (n = 28) tended to have larger minimal cross-sectional area (MCA) compared with those of patients whose RDI was more than 30/h (n = 33) (P = 0.001). A stepwise multiple regression analysis showed that BMI, male gender, and MCA were contributing factors in RDI. The R2 value of the multiple regression analysis was 0.406.

CONCLUSION

Patients with severe OSA tended to have smaller MCA when compared with patients with RDI less than 30/h. However, it was hard to predict whether patients had OSA from acoustic rhinometry examination.

The effect of allergen provocation on the nasal cycle estimated by acoustic rhinometry

CONCLUSION

The overall duration and reciprocity of the nasal cycle were not changed after allergen provocation. The duration of immediate response was 38 min, but the amplitude of the nasal cycle was increased significantly after allergen provocation.

OBJECTIVE

Nasal airflow is asymmetrical and subjected to spontaneous reciprocal changes which are referred to as the nasal cycle. Limited information is available on how this is affected by allergens. The purpose of this study was to evaluate the effects of allergen provocation on the nasal cycle.

MATERIALS AND METHODS

This study was performed on 25 patients with allergic rhinitis and 25 subjects in a control group with no symptoms of allergic rhinitis. Acoustic rhinometry was used to test patients before and after allergen provocation. The patients underwent acoustic rhinometry at 15-min intervals for evaluation of nasal cycle and 3-min intervals for immediate response.

RESULTS

With the allergic patients, 21 of the 25 patients (84.0%) showed a nasal cycle and they still had a nasal cycle after the allergen provocation. In the study on the changes in the immediate responses, the average recovery time was 38 min and the reduction rate of the non-patent side was higher than that of the patent side. Also, the average period of the nasal cycle was 153 min before the allergen provocation and 140 min on average after the allergen provocation; there were no statistical differences. The amplitude of each nasal cycle increased after allergen provocation and the difference had statistical meaning.

Sit Up and Smell the Roses Better: Olfactory Sensitivity to Phenyl Ethyl Alcohol Is Dependent on Body Position

Previous studies have demonstrated that body position can alter auditory sensitivity. Here we demonstrate for the first time that olfactory sensitivity for the commonly used odor phenyl ethyl alcohol (PEA) (rose odor) is also dependent on body position. By using successive dilutions presented in a staircase protocol, we determined olfactory thresholds for PEA in 36 healthy participants (18 women) in both an upright and a supine position. Participants had a significantly greater olfactory sensitivity when tested in an upright than a supine position, with no significant differences between the sexes. This preliminary study sets the stage for further work on the interaction between olfactory functions and our biology. The implications for olfactory neuroimaging studies are discussed.

Effects of posture change on nasal patency

Nasal obstruction when lying down frequently brings patients to the otolaryngologic clinic. There are several explanations for the problem. The nasal mucosa reaction to venous changes that alter local blood flow, secondary to compression of the neck veins or hydrostatic pressures, is the most accepted explanation. Acoustic rhinometry is a new non-invasive technique to assess nasal patency. Aim: The purpose of this study was to assess the effect of posture change from sitting to supine position applying acoustic rhinometry. Study design: clinical prospective. Material and method: 10 volunteers with no nasal disorders, aged 19 to 30 years old, and 10 volunteers with symptoms of rhinitis, aged 18 to 27 years old, were selected for the study. Nasal sensation was tested by means of a visual analogue scale. Nasal area and volume were assessed by acoustic rhinometry in the following positions: seated and 15 minutes after lying down. Results: Both groups showed significant nasal obstruction on the visual analogue scale and on acoustic rhinometry. The perception of nasal obstruction was significantly higher in subjects with rhinitis symptoms compared to normal. Conclusion: We conclude that the effect of posture change from sitting to supine position produces a decrease in nasal cross-sectional area and volume in both normal and in subjects with symptoms of rhinitis. However, the impact on the perception of nasal obstruction induced by lying down seems to be higher in subjects with symptoms of rhinitis.

Efeitos da alteração de postura sobre a permeabilidade nasal

Obstrução nasal ao deitar é uma experiência comumente relatada na clínica diária otorrinolaringológica. Das explicações postuladas destacam-se as alterações das pressões venosas que afetam o conteúdo sangüíneo da mucosa nasal, quer por compressão da veia do pescoço, quer por diferenças hidrostáticas. A rinometria acústica é uma técnica não-invasiva de aferição objetiva da permeabilidade nasal. A reflexão de ondas sonoras é analisada para gerar um gráfico de áreas intranasais. OBJETIVO: Os objetivos deste estudo foram aferir por meio da rinometria acústica o efeito da alteração de postura sobre a permeabilidade nasal entre as posições sentada e deitada. FORMA DE ESTUDO: clínico prospectivo. MATERIAL E MÉTODO: Dez voluntários normais com idades entre 19 e 30 anos e 10 riníticos com idades entre 18 e 27 anos foram selecionados. A percepção de respiração nasal foi testada por meio de uma escala analógica visual e a área e volume nasal por meio de rinometria acústica nas posições sentado e 15 minutos após deitar. RESULTADO: Ambos os grupos mostraram a ocorrência significativa de obstrução nasal tanto na análise da percepção como também na área e no volume nasal. Nos participantes com história de rinite, a percepção de obstrução nasal foi significativamente maior do que no grupo de normais em todas as posições estudadas. CONCLUSÃO: Concluímos que a alteração de postura da posição sentada para a deitada piora a área e o volume nasal tanto em indivíduos normais como em indivíduos com história de rinite. Contudo indivíduos com história clínica de rinite são mais sensíveis à percepção de obstrução nasal induzida pelo decúbito dorsal.

Nasal obstruction and sleep-disordered breathing: the effect of supine body position on nasal measurements in snorers

OBJECTIVE

Nasal obstruction is considered to be a potential etiological factor in sleep-disordered breathing. However, a significant correlation between nasal measurements and obstructive sleep apnea has not been demonstrated so far. The aim of this study was to investigate the relationships between nasal resistance, nasal volumes and selected sleep parameters using nasal measurements performed in both seated and supine positions. We also investigated whether snoring patients in our clinical sample showed increased positional or decongestive nasal mucosal changes.

MATERIAL AND METHODS

Forty-one snoring men on a waiting list for correction of nasal obstruction underwent polysomnography, anterior rhinomanometry and acoustic rhinometry. Nineteen non-snoring control subjects were also recruited. Nasal measurements were performed in a seated position, after lying down in a supine position and, after decongestion of nasal mucosa, in a seated position again.

RESULTS

In the overall patient group, nasal volume at a distance 2-4 cm from the nares in the supine position correlated inversely with apnea-hypopnea index (AHI) (r = -0.32, p < 0.05) and oxygen desaturation index (ODI) (r = -0.49, p < 0.05). In the non-obese patients, total nasal resistance measured in a supine position correlated with AHI (r = 0.50, p < 0.05) and ODI (r = 0.58, p < 0.05) and supine nasal volumes were also inversely correlated with ODI. No significant correlations were found between baseline nasal measurements performed in a seated position and sleep parameters. Postural or decongestive changes in nasal measurements were not increased in snoring patients compared with control subjects.

CONCLUSION

The relationship found between nasal measurements and sleep parameters suggests that nasal obstruction does augment airway collapse.

Nasal patency is related to dust exposure in woodworkers

OBJECTIVES

A cross sectional study of 54 furniture factories and three control factories was conducted to investigate the relation between subjective and objective nasal obstruction and exposure to wood dust.

METHODS

Acoustic rhinometry was performed on 161 woodworkers and 19 controls. For each person, four measuring rounds were performed: before work, after 4 hours of work, and after 7 hours of work before and after decongestion. Before the first and third measuring round, each person rated the current feeling of nasal obstruction in the left and right nostril separately, using a visual analogue scale. Personal passive dust measurements were performed on 140 woodworkers.

RESULTS

The mean (SD) of equivalent inhalable dust was relatively low, 1.17 (0.62) mg/m(3), range 0.17-3.44 mg/m(3). The exposure was divided into four levels: controls, low exposure, medium exposure, and high exposure. For the two highest concentrations of exposure, a significant increase in congestion--decreased nasal cavity volume and cross sectional areas--was found after 4 and 7 hours of work, compared with before work. Multivariate linear regression analysis showed positive correlations between concentration of dust and change in mucosal swelling. A significant increase in self rated nasal obstruction was found after work compared with before work for the two highest exposure groups. No correlation between objective nasal variables and self rated nasal obstruction was found.

CONCLUSION

Exposure to wood dust was related in a dose dependent manner to acute nasal obstruction measured by acoustic rhinometry and self reported obstruction, but no correlation was found between measured and self reported obstruction.

Supine position decreases the ability of the nose to warm and humidify air

We tested the hypothesis that decreasing nasal air volume (i.e., increasing nasal turbinate blood volume) improves nasal air conditioning. We performed a randomized, two-way crossover study on the conditioning capacity of the nose in six healthy subjects in the supine and upright position. Cold, dry air (CDA) was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before it entered and after it exited the nasal cavity. The total water gradient (TWG) across the nose was calculated and represents the nasal conditioning capacity. Nasal volume decreased significantly from baseline without changing the mucosal temperature when subjects were placed in the supine position (P < 0.01). TWG in supine position was significantly lower than that in upright position (P < 0.001). In the supine position, nasal mucosal temperature after CDA exposure was significantly lower than that in upright position (P < 0.01). Our data show that placing subjects in the supine position decreased the ability of the nose to condition CDA compared with the upright position, in contrast to our hypothesis.

Intranasal challenge with aspirin in the diagnosis of aspirin intolerant asthma: evaluation of nasal response by acoustic rhinometry

BACKGROUND

Nasal provocation tests with lysine-aspirin have recently been introduced for assessment of aspirin intolerant asthma. A study was undertaken to evaluate the usefulness of acoustic rhinometry, a new non-invasive technique, in the diagnosis of aspirin intolerant asthma/rhinitis.

METHODS

Fifteen patients with aspirin intolerant asthma/rhinitis (nine women, mean (SD) age 54.7 (14) years), eight patients with aspirin tolerant asthma/rhinitis (three women, mean (SD) age 52.6 (7.8) years), and eight healthy subjects (two women, mean (SD) age 32.5 (9.7) years) were studied. All subjects were challenged with saline (0.9% NaCl) and 25 mg lysine acetylsalicylic acid (L-ASA) instilled into each nostril of the nose on two separate days. The clinical response was evaluated based on nasal symptoms (sneezes, itching, secretion and blockage). The nasal response was measured by acoustic rhinometry. Symptoms and rhinometry curves were recorded at 10 minute intervals for three hours, one hour before challenge and two hours after challenge.

RESULTS

L-ASA challenge induced a significant increase in symptoms in patients with aspirin intolerant asthma/rhinitis. No differences in the clinical response were detected in those with aspirin tolerant asthma/rhinitis or healthy subjects. L-ASA challenge induced a significant decrease in nasal volume measured by acoustic rhinometry in aspirin intolerant patients. No differences were detected between the challenges in aspirin tolerant patients. If a 25% decrease in nasal volume is taken as the cut off point, the specificity of the test was 94% and the sensitivity reached 73%. The nasal challenge was well tolerated by all subjects.

CONCLUSION

Acoustic rhinometry may be used to study the nasal response to L-ASA. Nasal challenge with L-ASA is safe and can be used as a diagnostic test even in asthmatic patients with severe bronchial obstruction.

Nasal hyperreactivity to methacholine measured by acoustic rhinometry in asymptomatic allergic and perennial nonallergic rhinitis

This study was carried out to assess nasal response to different doses of methacholine and to evaluate the diagnostic possibilities of this test. Thirty-seven patients with allergic rhinitis induced by pollen (out of season), 16 with nonallergic rhinitis, and 25 normal subjects were evaluated. After provocation with saline, increasing doses of methacholine, ranging from 0.5 to 16 mg/mL, were applied. Nasal obstruction was assessed by acoustic rhinometry 10 minutes after each dose, the minimum cross-sectional area and the nasal volume in both fossae were obtained. Ipratropium bromide was applied after the last dose of methacholine to evaluate reversibility. After methacholine challenge with 0.5, 1, 2, and 4 mg/mL there was a statistically significant decrease (p < 0.05) in nasal area and volume in a dose-dependent manner in patients with allergic and nonallergic rhinitis in comparison with controls. A ROC (receiver-operating characteristic) analysis showed that a decrease in nasal volume > or = 20% at methacholine concentration of 2 mg/mL is able to predict the presence of rhinitis (positive predicted value 93%, negative predicted value 79%) in 75% of subjects. The clinical relevance of this finding suggests that patients with symptomatic nonallergic rhinitis or even asymptomatic patients with allergic rhinitis out of pollen season present a nasal hyperreactivity to methacholine, and that a decrease of nasal volume > 20% by acoustic rhinometry after challenge with methacholine at 2 mg/mL is able to discriminate these patients from normal subjects. This method seems to be a suitable tool in the diagnosis of rhinitis.

Acoustic rhinometry of the oriental nose

Most studies have established normal values for acoustic rhinometric (AR) analysis of the nasal passage based on a primarily caucasian or mixed population. Because consistent anatomic differences do occur in anthropomorphic measurements of the nose of different races, AR analysis was performed on an Asian population to determine whether differences occurred in the minimum cross-sectional area (MCA). AR with expanded testing was performed on a non-Asian control group and an Asian study population containing 28 subjects, with 56 half-cavities (F: 20; M: 8; age range 21-58), including 16 Vietnamese, 8 Korean, 4 Thai, all of whom had physically typical mesorrhine noses. In the Asian population, the mean MCA of each half-cavity was 0.56 +/- 0.16 cm2, and 39.3% of subjects had significant asymmetry between their two half-cavities. The mean MCA increased to 0.67 +/- 0.12 cm2 after the placement of a Breathe Right Strip Dilator (BRSD) over the nasal bridge, which was a significant increase in 32% of subjects, and to 0.68 +/- 0.14 cm2 after the application of 1% Neosinephrine, a significant increase in 34% of those tested compared to the resting state. The combination of BRSD and Neosinephrine produced an MCA of 0.72 +/- 0.11 cm2, which was a statistically significant increase in 24 half-cavities (43%). Compared to our non-Asian population, the Asian group had fewer subjects with significant asymmetry (39% versus 59%) before expanded testing and fewer responders to BRSD (48% versus 79%).

Changes in nasal resistance and nasal geometry using pressure and acoustic rhinometry in a feline model of nasal congestion

This is the first report describing the use and pharmacological characterization of nasal patency by both pressure rhinometry and acoustic rhinometry (AcR) in an experimental cat model of nasal congestion. In pressure rhinometry studies, aerosolized compound 48/80 (0.1-3.0%), a mast cell liberator, increased nasal airway resistance (NAR) 1.2 +/- 0.6, 5.8 +/- 0.5, 8.6 +/- 1.1 and 7.9 +/- 1.5 cmH2O.L/minute, respectively. Increases in NAR produced by compound 48/80 were associated with a 395% increase in histamine concentration found in the nasal lavage fluid. Pretreatment with the alpha-adrenoreceptor agonist, phenylpropanolamine (PPA; 0.1-3.0 mg/kg, i.v.), and the NO synthetase inhibitor, NG-nitro-L-arginine (L-NAME; 10 mg/kg, i.v.) attenuated the increases in NAR produced by compound 48/80. The histamine H1 antagonist chlorpheniramine (1.0 mg/kg, i.v.) and the H2 antagonist, ranitidine (1.0 mg/kg, i.v.) had no decongestant activity. Also without decongestant activity were the muscarinic antagonist atropine, the cyclooxygenase inhibitor indomethacin, and the 5-HT blocker methysergide. Aerosolized histamine (0.1-1.0%) also produced a dose dependent increase in NAR. In studies using acoustic rhinometry (AcR), intranasal application of compound 48/80 (0.1-1.0%) elicited pronounced decreases in nasal cavity volumes and minimum cross-sectional area (Amin). Pretreatment with PPA (3 mg/kg, i.v. or 10 mg/kg, p.o.) attenuated the decreases in nasal volume and Amin. The effects of topical intranasal histamine (0.1-1.0%) on nasal geometry were similar to compound 48/80. We conclude that the cat is a useful model for evaluating the pharmacological actions of potential nasal decongestants. Furthermore, we also conclude that AcR is a useful method for noninvasive assessment of nasal patency in a preclinical setting.

Evaluation of the nasal cavity by acoustic rhinometry in normal and allergic subjects

With acoustic rhinometry, one can detect a difference in response to a topical decongestant between normal and allergic subjects at the minimal cross-sectional area. The minimal cross-sectional area corresponds in most cases to the anterior end of the inferior turbinate or the first valley, which occurs after the nose piece of the acoustic rhinometer on the acoustic rhinometry graph. Allergic patients typically have an increase in nasal mucosal swelling, which leads to a decrease in the nasal volume and area and, subsequently, to an increase in congestion. In this study acoustic rhinometry was used to test normal and allergic subjects before and after the application of a topical decongestant (1% phenylephrine (Neo-Synephrine)). Symptoms were measured by a five-point scale. Results showed that increasing symptom scores demonstrated a trend toward being related to decreasing area as measured at the minimal cross-sectional area or nasal valve. The average total percent change at the minimal cross-sectional area was calculated for both groups and compared. The normal subjects had an average total percent area change at the minimal cross-sectional area of 15.6% ± 14.8%, and the allergic subjects had a percent change of 24.6% ± 20.8%. This represents a significant difference between the normal and allergic subjects in response to the topical decongestant at the minimal cross-sectional area ( p = 0.04). However, the average total percent change was not significantly different between the two groups at the second and third valleys. At the second valley, the normal subjects had a percent change of 40% ± 17.5%, and the allergic subjects had a percent change of 36% ± 18.5%. At the third valley, the normal subjects had a percent change of 35% ± 15.4%, and the allergic subjects had a percent change of 32% ± 20.6% ( p = 0.4 and 0.5, respectively). The total area was calculated by adding measurements from both right and left nasal cavities for each subject in an attempt to control the effect of the nasal cycle. Acoustic rhinometry makes it possible to detect a trend in the relationship between either a decrease in area at the minimal cross-sectional area or a decrease in the total volume from 0 to 7 cm into the nasal cavity and congestion. A statistically significant difference between normal and allergic subjects in their response to a topical decongestant at the minimal cross-sectional area was detected by acoustic rhinometry at the nasal valve.

Acoustic rhinometry in the study of the acute nasal allergic response

Acoustic rhinometry is a recently developed method for the objective assessment of nasal patency. In this study, acoustic rhinometry was used to measure changes in nasal cavity dimensions in the immediate response to nasal allergen challenge in eight pollen-sensitive subjects. Acoustic rhinometric changes were compared with subjective symptoms, as well as histamine in nasal secretions, cytology of nasal mucosal scrapings, and changes in olfactory function. A significantly greater decrease in nasal airway caliber occurred following allergen challenge as compared to buffer diluent challenge in the same individuals (70% +/- 7% versus 22% +/- 5%). During an allergic response, a strong correlation was found between the minimum cross-sectional area and the volume of the nasal cavity measured by acoustic rhinometry (r = .9). However, no correlation was observed between nasal airway caliber and concomitant subjective congestion reported by the subjects. A modest decrease in olfactory function was seen following allergen challenge (3.1 +/- 1.4 fewer odors identified correctly out of 20; p = .08). However, the alterations of olfactory function did not correlate with changes in nasal patency. The results presented in this study demonstrate that acoustic rhinometry has great potential as a reproducible method for the objective assessment of nasal obstruction occurring in nasal allergen challenge studies.

Acoustic rhinometry: do we need a standardized operating procedure?

The usefulness of a standardized operating procedure for acoustic rhinometry was assessed in a study on 51 healthy volunteers. Nasal measurements were made with acoustic rhinometry before and after application of a topical nasal decongestant. Our standard operating procedure used three consecutive readings of anterior nasal volume to obtain a valid estimate of mean nasal dimensions. The mean measurement was only accepted as valid if the three readings had a coefficient of variation (CV) of less than 20%. Twenty-two out of 192 (11.5%) nasal cavities required more than three consecutive readings to achieve this. Our data show that the error encountered by relying on a single reading of an acoustic trace can be greater than the changes caused by the topical nasal decongestant and that multiple readings using a standard operating procedure are essential to obtain valid data.