The impact of expiration on particle deposition within the nasal cavity

One of the most important functions of the nose is cleansing the inspired air. The aim of this study was to compare the intranasal deposition of particles during inspiration and expiration, applying different breathing manoeuvres. In nine subjects, the non-deposited particles during inhalation of an aerosol of starch particles were laser-optically detected by placing a suction probe transnasally in the anterior nasal segment. The particle deposition was measured during cyclical nose-in/nose-out (nose-only) and nose-in/mouth-out breathing. The deposited fraction was calculated in percentages. Active anterior rhinomanometry and acoustic rhinometry were performed. The mean deposited fraction in the anterior nasal segment was statistically significantly higher (P < 0.02) during nose-only breathing (46.0%) compared with nose-in/mouth-out breathing (33.0%). Our results suggest that intranasal particle deposition takes place during inspiration as well as during expiration. The period of expiration does not only seem to be important for water and heat recovery, but also for cleansing of the respiratory air.     

Impact of resection of the turbinates and the lateral nasal wall on particle deposition

OBJECTIVES/HYPOTHESIS: The aim of the investigation was to determine the influence of complete resection of the turbinates and the lateral nasal wall on nasal deposition of particulate matter with an aerodynamic diameter of 10 microm or less (pm10) and its relation to nasal patency and geometry. STUDY DESIGN: Retrospective study. METHODS: Eight patients were enrolled in the study after unilateral sinus surgery for a unilateral inverted papilloma of the sinuses. Particle deposition from the inhaled and exhaled air was measured by means of a laser particle counter in the nasal valve area and the nasopharynx during nose-only breathing and nose-in, mouth-out breathing. The data on deposited fraction for the operated side were compared with the data for the untreated, healthy side. Rhinomanometry and acoustic rhinometry were performed. RESULTS: Particle deposition did not differ significantly between the operated and untreated sides of the nose at both detection sites. No correlation between the deposited fraction and rhinomanometric and rhinometric values was found. CONCLUSION: Radical resection of the turbinates does not seem to disturb particle deposition (pm10) measured in the nose to a significant degree. Factors other than impaction and sedimentation onto the mucosal surface of the turbinates seem to be sufficient for effective particle deposition after radical removal of the turbinates.     

Value of acoustic rhinometry for measuring nasal valve area

OBJECTIVE: To assess the validity of acoustic rhinometry for measuring nasal valve area in human subjects. STUDY DESIGN: A comprehensive study that compared acoustic rhinometry data with computed tomography findings from scans obtained perpendicular to the acoustic axis and perpendicular to the floor of the nose. METHODS: Fifty nasal passages of 25 healthy adults with no nasal disease were examined by acoustic rhinometry and computed tomography. In each case, the area of the nasal valve as measured by acoustic rhinometry was compared with the area calculations from computed tomography sections taken in two different coronal planes, one perpendicular to the acoustic axis and one perpendicular to the floor of the nose. Computed tomography slices perpendicular to the floor of the nose were obtained at two different locations, a specific distance from the tip of the nose and a specific distance from the anterior nasal spine. RESULTS: There was a significant correlation between the nasal valve areas determined by acoustic rhinometry and computed tomography when imaging was obtained perpendicular to the acoustic axis. In contrast, when scanning was obtained perpendicular to the straight axis of the floor of the nose, the correlations between the acoustic rhinometry and computed tomography data were weak. CONCLUSIONS: When any type of imaging is used for comparison with nasal valve areas determined by acoustic rhinometry, the cross-sections should be perpendicular to the acoustic pathway. The results of the study show that acoustic rhinometry is a valuable method for measuring nasal valve area.     

Acoustic rhinometry compared with anterior rhinomanometry in the assessment of the response to nasal allergen challenge

Acoustic rhinometry was used to assess nasal airway patency objectively and was compared with the more established method of anterior rhinomanometry. Ten patients with allergic rhinitis underwent 15 nasal challenges with allergen to which they showed positive skin-prick tests. Responses were assessed by measuring the minimum nasal cross-sectional area (Amin.) using acoustic rhinometry and by measuring nasal airway resistance (NAR) using anterior rhinomanometry. The measurements of Amin. and NAR showed a significant negative correlation. Acoustic rhinometry appears to be superior to anterior rhinomanometry in quantifying the response to nasal allergen challenge and may be particularly useful in patients with initial nasal blockage.     

Influence of personal factors on nasal patency and lavage biomarkers in white-collar workers

Large biological variability between subjects has been shown for both acoustic rhinometry and nasal lavage biomarker concentrations, but relatively little is known about the influence of personal factors on these techniques. The aim was to evaluate if nasal symptoms, acoustic rhinometric measurements and nasal lavage fluid biomarkers are related to age, gender, smoking, atopy or asthma. A standardized nasal investigation was applied in 411 white-collar workers, belonging to three occupational groups: school personnel (n = 234), office workers (n = 89) and hospital workers (n = 88). Lavage fluid analysis included determination of eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme and albumin. Females had smaller nasal dimensions in the anterior part of the nose (p < 0.001), and lower lavage fluid concentrations of ECP (p = 0.004), MPO (p = 0.002), and albumin (p = 0.01). Rhinometric dimensions or lavage fluid biomarker concentrations were not related to age, smoking, atopy or asthma. Some differences in rhinometric and biomarker measurements were observed between the occupational groups, and adjustment was made for occupation. Rhinometric measures and lavage biomarkers were consistently interrelated, which suggests a combined mucosal swelling and inflammatory reaction. This indicates a potential usefulness of a combined use of acoustic rhinometry and lavage biomarkers to study nasal mucosal reactions.     

Correlation between rhinometric measurement methods in healthy young adults

The most common rhinometric measurement methods used in modern rhinology are acoustic rhinometry, rhinomanometry, and nasal peak expiratory flow (PEF) rate. In this prospective study, we wanted to clarifiy whether the parameters given by these three methods in the same subject support each other and can be used simultaneously in clinical practice. We also wanted to define the dimensions of normal nasal geometry and function based on these three methods. The rhinometric measurements were done in 249 healthy white subjects consisting of 171 women and 78 men. The geometry was analyzed with regard to body mass index (BMI) and smoking habits. The result could he used as some kind of reference value for the same kind of patient cohort as when rhinological pathology is investigated. The measurements obtained by acoustic rhinometry showed only statistically significant correlations between the measured volume and minimal cross-sectional area in the nasal cavities (r = 0.959). Rhinomanometry showed only a statistically significant correlation between the measured resistance in expiration and inspiration (r = 0.977). Acoustic rhinometry, rhinomanometry, and nasal PEF did not show any correlations and the BMI did not have any effect on the results. Although the smoking group was relatively small in this cohort, the rhinometric methods showed smaller nasal cavity volume, higher resistance, and lower nasal PEF values. Based on these results, we recommend the use of these three rhinometric methods as independent instruments in rhinological examinations. However, in the pathological nose, e.g., smokers, the methods show equal changes in measurements. It is important to measure at least acoustic rhinometry and rhinomanometry at the same time in clinical practice to achieve good quality of examinations.     

Effect of the external nasal dilator on nasal minimal cross-sectional area in orientals as assessed by acoustic rhinometry.

OBJECTIVE: This study aimed to evaluate the effect of the external nasal dilator on the dimension of the nasal valve in Orientals. DESIGN: A cohort study of normal subjects. SETTING: Academic institution. METHODS: The nasal fossae of normal subjects were assessed by acoustic rhinometry before and after application of the external nasal dilator. MAIN OUTCOME MEASURES: The minimal cross-sectional area of the nasal fossae and the total cross-sectional area of the nose. RESULTS: Nasal fossae of 25 normal subjects were evaluated. There was a significant increase of 0.10 cm2 (SD = 0.16) or a 17% increase in the minimal cross-sectional area of the 50 nasal cavities after application of the external nasal dilator (Wilcoxon's matched-pairs signed rank test, p = .0001). A significant increase in the total minimal cross-sectional area for the whole nose after application was also present (0.19 cm2, SD = .27, or 16%; Wilcoxon's matched-pairs signed rank test, p = .0032). CONCLUSIONS: The external nasal dilator results in an increase in the minimal cross-sectional area of the nasal airway in Orientals.     

The combination of acoustic rhinometry, rhinoresistometry and flow simulation in noses before and after turbinate surgery: a model study

BACKGROUND: Especially to young examiners, the interpretation of rhinometric findings seems to be difficult. In order to understand rhinometric assessments precisely, knowledge of airflow behavior in the nose is necessary. We therefore investigated the influence of nasal concha surgery on acoustic rhinometry and rhinoresistometry in a model. METHOD: Six nose models were examined with acoustic rhinometry and rhinoresistometry, each of these models with its lateral wall altered to represent various conditions after nasal concha surgery. Besides, all models were rinsed with water and the flow was visualized for observation. RESULTS AND CONCLUSIONS: The normal nose presented an even flow distribution over the entire nasal cavity. After nasal concha resection, though, an unfavorable flow course and a strong increase in turbulence were seen. Additionally, flow resistance decreased considerably. In the model with general lateral wall hyperplasia, reduction of the inferior and even of the middle nasal concha showed good functional results. The model revealed a good correlation between the result of flow observation and findings in acoustic rhinometry and rhinoresistometry. Both methods complement one another in their diagnostic outcome.     

Acoustic rhinometry: evaluation of the nasal cavity with septal deviations, before and after septoplasty

We introduce acoustic rhinometry as a new, objective method to assess the geometry of the nasal cavity. The cross-sectional area of the nasal cavity as a function of distance from the nostrils was obtained. A group of 21 patients with septal deformities was examined with acoustic rhinometry preoperatively and postoperatively. These values were compared with those of 21 normal control subjects. The minimal cross-sectional area (MCA) is located in the anterior part of the nose, and it shifts anteriorly under the effect of decongestion. The preoperative value of MCA is related to the location and severity of the anterior septal deformity. Postoperative smaller MCA found in the opposite side of that narrowed by a severe anterior septal deformity may be explained by the impact of septoplasty without reduction of a hypertrophic turbinate. A highly significant relation between MCA and the subjective feeling of nasal patency, before and after surgery, suggests that MCA is a valuable parameter to express nasal patency. Correction of posterior septal deformities is found to increase significantly the cross-sectional area posteriorly. The effect of decongestion in the postoperative values, however, suggests that the mucosa contributes even more to the cross-sectional area of the posterior part of the nose. Acoustic rhinometry seems very suitable for evaluation of the nasal cavity in cases where septoplasty and turbinoplasty is considered, as well as for the postoperative evaluation.     

Correlation between acoustic rhinometry and subjective nasal patency during nasal challenge test in subjects with suspected occupational rhinitis; a prospective controlled study

Clin. Otolaryngol. 2010, 35 , 462–467 Objectives: To assess the correlation between acoustic rhinometry and visual analogue scale endpoints in the context of nasal challenge with occupational agents. Design: Prospective controlled study. Setting: University teaching hospital. Participants: Sixty-seven subjects with a history of work-related rhinitis and asthma symptoms. Main outcomes measures: Subjects underwent nasal challenge with control and specific agent on consecutive days. Nasal congestive response to challenge was monitored by acoustic rhinometry and visual analogue scale. Results: Results showed no correlation between visual analogue scale and acoustic rhinometry measurements at baseline on the control (r = −0.13, P = 0.3) and active (r = 0.14, P = 0.2) challenge days. No correlation was found between acoustic rhinometry and visual analogue scale when analysing all measurements obtained at all times after challenge with the control and active agent (control: r = 0.09, P = 0.04; active: r = 0.001, P = 0.9). The correlation between acoustic rhinometry and visual analogue scale was good and significant (r = −0.62, P = <0.01) when the analysis was restricted to cases showing a decrease in nasal volume >40% from baseline values. Conclusions: We showed that the correlation between acoustic rhinometry and subjective nasal patency was poor on steady conditions. However, a significant correlation was observed in those cases showing a greater nasal congestive response after challenge measured by acoustic rhinometry.     

Detection of particles within the nasal airways before and after nasal decongestion

Cleansing of the air is one of the most important functions of the nose. The aim of this investigation was to determine the influence of decongestion of the nasal mucosa with xylometazoline on the intranasal particle deposition at different sites of the nasal cavity. During respiration of an aerosol of starch particles, the non-deposited particles in the air were laseroptically detected in 10 healthy volunteers by a transnasally placed suction probe at different locations within the nasal cavity. The anterior nasal segment was the main area of intranasal particle deposition before and after decongestion of the nasal mucosa. Particle deposition after nasal decongestion was not significantly different from the values before application of xylometazoline. Decongestion of the nasal mucosa and increase in nasal cavity diameter seems not to influence particle deposition of inhaled and exhaled air within a short period after onset of the maximal decongestive effect of xylometazoline.     

Detection of the nasal cycle

The nasal cycle is a fluctuation of nasal patency due to the stages of congestion and decongestion of the nasal mucosa on both the right and left nasal conchae. We compared the effectiveness of the rhinostereometer in detecting the presence of a nasal cycle with the acoustic rhinometer whose effectiveness we have demonstrated in previous studies. The rhinostereometer measures the horizontal range of the most anterior portion of the inferior turbinate. The acoustic rhinometer measures the volume and various cross-sectional areas of the nostril using a pulse emitted from a sound tube. Among some of the subjects tested, it was found that rhinostereometer and acoustic rhinometer measurements of nasal patency correlated reasonably well with r values up to 0.78. The overall correlation between rhinostereometry and acoustic rhinometry was not as strong at r = 0.36. Observed variations between rhinostereometry and acoustic rhinometry could be a result of certain confounding variables that may have altered the nasal cycle between measurements.     

Acoustic rhinometry: an explanation of some common artefacts associated with nasal decongestion

The nasal cavities of 51 healthy volunteers were examined using acoustic rhinometry before and after nasal decongestant. Several specific dimensions were studied, which included the minimum cross-sectional area, and three volumes corresponding to the anterior, middle and posterior regions of the nasal airway. An average acoustic rhinometry trace was constructed for the whole group of subjects, before and after decongestion, from data extracted from the raw data files written to the computer hard disk for each subject. A 27.5% (P < 0.0001) increase in the minimum cross-sectional area was observed, with no shift in its position. The greatest increase in nasal dimensions was seen in the anterior and middle parts of the nose, however, significant changes were also seen in the posterior nasal cavity and post nasal space. There are a number of possible sources of artefact. First, confusion of the first and second minima may produce apparent movement of the minimum cross-sectional area following nasal decongestion. Second, a postulated change in the acoustic path length may lead to apparent changes in volume in certain regions of the nose. Third, a variable and uncontrollable degree of sound energy loss will occur into the opposite nasal cavity beyond the posterior border of the septum. An apparent increase in the dimensions of this region will be seen as the opposite cavity decongests. We feel that all users of the acoustic rhinometer need to be aware of these potential sources of artefact, and attention needs to be focused on an agreed definition of the components of the acoustic rhinometry trace.     

Investigating the nasal cycle using endoscopy,rhinoresistometry, and acoustic rhinometry

OBJECTIVES: Cyclic congestion and decongestion in the two nasal cavities is seen in connection with the respiratory function of the nose. The turbulent behavior of nasal airflow is a prerequisite for adequate contact of inspired air particles with the mucosa. The aim of this study was to gain insight into this turbulent behavior of nasal airflow during the nasal cycle. METHODS: The nasal cycle in 10 healthy human subjects was investigated using endoscopic imaging, rhinoresistometry, and acoustic rhinometry every 20 minutes over a time period of up to 15 hours. The following parameters were recorded for each nasal cavity: airflow resistance, hydraulic diameter, friction coefficient lambda as an indicator for the wall configuration triggering turbulence, transition from laminar to turbulent flow, and the minimal cross-sectional areas. RESULTS: In addition to the known cyclic change of flow resistance and nasal width, a periodic change in the turbulence behavior was observed. In the resting phase, mainly laminar flow was found. During the working phase, the onset of turbulence occurred already at low flow velocities. The increase of turbulence during the working phase is caused by the increase in cross-sectional area in the anterior cavum due to decongestion of the mucosa of the head of the inferior turbinate and the septal tuberculum. CONCLUSIONS: Rhinoresistometry and acoustic rhinometry complement each other. The combination of the two methods provides insight into the functional changes during the nasal cycle and into nasal physiology in general. The authors therefore advocate a combination of the two methods for functional evaluation of the nasal airway.     

Evaluation of nasal cavity by acoustic rhinometry in Chinese, Malay and Indian ethnic groups.

Acoustic rhinometry (AR) evaluates the geometry of the nasal cavity by measuring the minimum cross-sectional area (MCA) and nasal volume (V) by means of acoustic reflection. Understanding the normal and pathologic conditions of the internal nasal cavity using AR is important in the diagnosis of structural abnormalities in patients. The aim of this study was to investigate the normal range of AR parameters in healthy volunteers from three ethnic groups in Singapore: Chinese, Malay and Indian. We also attempted to evaluate the role of these measurements in the documentation of structural abnormalities in the nose. A total of 189 Singaporeans, aged > or = 18 years, were recruited from a nationwide survey study. They comprised 83 Chinese, 35 Malays and 71 Indians. Eighty-nine subjects had a rhinoscopically normal nose (Group 1), 77 had significant septal deviation (Group 2) and 23 had inferior turbinate hypertrophy (Group 3). AR was performed to measure the MCA at the anterior 1-5 cm from the nostril and the volume (V) between points at the nostril and 5 cm into the nose. A mean MCA (mMCA; equal to (L + R)/2) and a total volume (Vt; equal to L + R) were then calculated for each subject, where L and R refer to the measurements made for the left and right nostrils, respectively. The results showed that there was no statistically significant difference in mMCA (p = 0.80) and Vt (p = 0.60) among the three ethnic subgroups of Group 1. Statistically significant differences were found only between Groups 1 and 3 (p < 0.001 for both mMCA and Vt) and between Groups 2 and 3 (p = 0.001 for mMCA and p = 0.013 for Vt). Although there was no significant difference between Groups 1 and 2, significant differences in MCA (p = 0.001) and V (p = 0.040) were found between the narrower sides (smaller volume) and the wider sides in Group 2, indicating volume compensation between the nasal cavities. In conclusion, our study demonstrates that there is no significant difference in the normal range of AR measurements among Chinese, Malay and Indian ethnic groups. AR is able to determine the structural abnormality of the internal nasal cavity caused by septal deviation and inferior turbinate hypertrophy.     

Measurement of nasal geometry by acoustic rhinometry in normal-breathing Asian children.

OBJECTIVE: The purpose of this study was to obtain normal values of nasal geometry in Asian children with no nasal problems using the acoustic rhinometry method. METHOD: Acoustic rhinometric measurement of the nasal fossae was performed in pediatric patients coming for general surgical operations with no nasal problem. RESULTS: A cohort study of 183 children in an acute care hospital with full elective and emergency surgical services was undertaken. The mean minimal cross-sectional area (MCA), which was functionally important for nasal breathing, was found to be 0.32 cm2 (SD = 0.13) and situated at 1.40 cm (SD = 0.26) from the anterior nare. Normal values for area, length, and volume of the nose in these children as a group and at different ages from 1 to 11 years old were obtained. CONCLUSIONS: Acoustic rhinometry was found to be well tolerated by the children. The MCA was confirmed to be situated at the anterior part of the nose and had a positive correlation with an increase in age.     

Increased net water loss by oral compared to nasal expiration in healthy subjects

AIM OF THE STUDY: To compare the difference in respiratory water loss during expiration through the nose and through the mouth, in healthy subjects. METHODS: The study included 19 healthy, non-smoking volunteers without any present history of non-infectious rhinitis, presenting with symptoms of rhinitis, asthma or previous nasal surgery. Nasal and oral expiratory breath condensates were collected using a breath condenser during tidal respiration at indoor resting conditions. During the nasal breath condensate sampling, the subjects were breathing into a transparent face mask covering the nose and the mouth with the mouth closed. During the oral breath condensate sampling, the subjects inhaled through the nose and exhaled through a mouthpiece connected to the condenser. The airflow during the sampling was assessed with a dry-spirometer connected to the condenser. Sampling was stopped after 100 litres of expired air for each breathing mode. Nasal sampling was done before and after decongestion of the nasal mucosa with oxymetazoline, 0.5 mg/ml. The effect on the nasal mucosa was assessed with acoustic rhinometry. RESULTS: The mean loss of expired water was 42% less by nasal expiration before decongestion than by oral expiration (1.9 x 10(-3) g/L min compared to 2.7 x 10(-3) g/L min, p < 0.001). The mean expiratory minute ventilation was 9.0 L/min by nasal respiration and 9.8 L/min by oral respiration. Decongestion of the nasal mucosa showed a mean increase of the cross-sectional area at 4 cm from the nostril (1.44 to 1.67 cm2, p = 0.0024), but there was no effect on the net water loss (1.9 x 10(-3) g/Lmin vs 1.9 x 10(-3) g/Lmin). CONCLUSION: This study showed that the net water loss increased by 42% when the breathing mode was switched from nasal to oral expiration during tidal breathing in healthy subjects. Increased water and energy loss by oral breathing could be a contributing factor to the symptoms seen in patients suffering from nasal obstruction.     

Evaluation of Nasal Cavity by Acoustic Rhinometry in Chinese,Malay and Indian Ethnic Groups

Acoustic rhinometry (AR) evaluates the geometry of the nasal cavity by measuring the minimum cross-sectional area (MCA) and nasal volume (V) by means of acoustic reflection. Understanding the normal and pathologic conditions of the internal nasal cavity using AR is important in the diagnosis of structural abnormalities in patients. The aim of this study was to investigate the normal range of AR parameters in healthy volunteers from three ethnic groups in Singapore: Chinese, Malay and Indian. We also attempted to evaluate the role of these measurements in the documentation of structural abnormalities in the nose. A total of 189 Singaporeans, aged &#83 18 years, were recruited from a nationwide survey study. They comprised 83 Chinese, 35 Malays and 71 Indians. Eighty-nine subjects had a rhinoscopically normal nose (Group 1), 77 had significant septal deviation (Group 2) and 23 had inferior turbinate hypertrophy (Group 3). AR was performed to measure the MCA at the anterior 1-5 cm from the nostril and the volume (V) between points at the nostril and 5 cm into the nose. A mean MCA (mMCA; equal to (L + R) 2) and a total volume (V t ; equal to L + R) were then calculated for each subject, where L and R refer to the measurements made for the left and right nostrils, respectively. The results showed that there was no statistically significant difference in mMCA ( p =0.80) and V t ( p = 0.60) among the three ethnic subgroups of Group 1. Statistically significant differences were found only between Groups 1 and 3 ( p < 0.001 for both mMCA and V t ) and between Groups 2 and 3 ( p = 0.001 for mMCA and p = 0.013 for V t ). Although there was no significant difference between Groups 1 and 2, significant differences in MCA ( p = 0.001) and V ( p = 0.040) were found between the narrower sides (smaller volume) and the wider sides in Group 2, indicating volume compensation between the nasal cavities. In conclusion, our study demonstrates that there is no significant difference in the normal range of AR measurements among Chinese, Malay and Indian ethnic groups. AR is able to determine the structural abnormality of the internal nasal cavity caused by septal deviation and inferior turbinate hypertrophy.     

Improving the reproducibility of acoustic rhinometry in the assessment of nasal function

Acoustic rhinometry readings are very position dependent, and it was hypothesized that this accounts for its relative lack of reproducibility on a day-to-day basis. Multiple readings on each visit were taken to investigate their impact, if any, on improving the day-to-day reproducibility of the method. Measurements of the minimal cross-sectional area of the nose as measured by acoustic rhinometry were studied in 10 subjects following nasal decongestion. For each individual, acoustic rhinometry was performed ten times. The ten recordings were repeated again, in an identical manner on a separate day. The subjects were repositioned and the nasal probes reinserted between each measurement. The mean coefficient of variation for minimal cross-sectional area readings in all 10 subjects was calculated as 9.92%. This is comparable to the day-to-day variability of acoustic rhinometry as measured by other workers and thus supports the hypothesis that the high measurement error of the device (rhinometer) is a function of positional variation during data acquisition. We were able to demonstrate a minimal gain in intervisit reproducibility by doing multiple recordings per person, with a plateau effect of reproducibility after 7 repeat readings.     

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.