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

Nasal Patency Measurement: State of the Art of Acoustic Rhinometry

Nasal obstruction is one of the main symptoms of different nasal pathologies. Many physiological and pathological conditions can produce nasal airflow impairment causing nasal obstruction and affecting patients' quality of life. There are different methods for the measurement of nasal obstruction, but in clinical practice the most common used are acoustic rhinometry, rhinomanometry, and peak nasal inspiratory flow. This review describes the fundamentals of acoustic rhinometry, its normal values, the different physiological and pathological conditions that can modify nasal patency, and the utility of this instrument for the measurement of nasal obstruction in clinical practice. Acoustic rhinometry is a simple test, so it is suitable for measurements in the pediatric population, i.e., for evaluating adenoid hypertrophy. Acoustic rhinometry normal values are available, unilaterally and bilaterally for pediatric and adult populations. Acoustic rhinometry has been demonstrated to be reproducible and even superior to rhinomanometry when measuring nasal modifications during challenges. It is possible to use acoustic rhinometry before and after nasal surgery. Measuring nasal cavities volume and cross-sectional area, acoustic rhinometry is particularly indicated in rhinosurgery, especially for the evaluation of spreader grafts. Brief considerations about the correlation between nasal symptoms, in particular the subjective sensation of nasal obstruction, and the acoustic rhinometry results as well as the correlation of acoustic rhinometry with other methods for the measurement of nasal obstruction are also reported. Objective and subjective evaluation of nasal obstruction gives different information that together optimizes the diagnosis and the treatment of rhinologic patients. Acoustic rhinometry alone or in combination of other instruments for the measurement of nasal obstruction or patency should be used regularly in every outpatient clinic that treats patients with nasal obstruction as there is an increasing need of evidence-based therapies.

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.

A new segmentation algorithm for measuring CBCT images of nasal airway: a pilot study

Background

Three-dimensional (3D) modeling of the nasal airway space is becoming increasingly important for assessment in breathing disorders. Processing cone beam computed tomography (CBCT) scans of this region is complicated, however, by the intricate anatomy of the sinuses compared to the simpler nasopharynx. A gold standard for these measures also is lacking. Previous work has shown that software programs can vary in accuracy and reproducibility outcomes of these measurements. This study reports the reproducibility and accuracy of an algorithm, airway segmentor (AS), designed for nasal airway space analysis using a 3D printed anthropomorphic nasal airway model.

Methods

To test reproducibility, two examiners independently used AS to edit and segment 10 nasal airway CBCT scans. The intra- and inter-examiner reproducibility of the nasal airway volume was evaluated using paired t-tests and intraclass correlation coefficients. For accuracy testing, the CBCT data for pairs of nasal cavities were 3D printed to form hollow shell models. The water-equivalent method was used to calculate the inner volume as the gold standard, and the models were then embedded into a dry human skull as a phantom and subjected to CBCT. AS, along with the software programs MIMICS 19.0 and INVIVO 5, was applied to calculate the inner volume of the models from the CBCT scan of the phantom. The accuracy was reported as a percentage of the gold standard.

Results

The intra-examiner reproducibility was high, and the inter-examiner reproducibility was clinically acceptable. AS and MIMICS presented accurate volume calculations, while INVIVO 5 significantly overestimated the mockup of the nasal airway volume.

Conclusion

With the aid of a 3D printing technique, the new algorithm AS was found to be a clinically reliable and accurate tool for the segmentation and reconstruction of the nasal airway space.

Management of Rhinitis Medicamentosa: A Systematic Review

OBJECTIVE

Rhinitis medicamentosa (RM) is a common condition resulting from overuse of topical nasal decongestants. Despite the prevalence in otolaryngologic practice, a clear treatment protocol has not been established. Our objective was to review the current published literature pertaining to the treatment of RM with the possibility of finding data that support one treatment over another.

DATA SOURCES

PubMed, Embase, Cochrane, and Web of Science databases were examined for patients diagnosed with RM resulting from chronic use of topical nasal decongestants.

REVIEW METHODS

The PRISMA standard (Preferred Reporting Items for Systematic Reviews and Meta-analyses) was utilized to identify English-language studies reporting treatment of patients with the primary diagnosis of RM after chronic use of a topical decongestant. Outcome measures of interest included patient-reported symptom relief and objective parameters. MINORS criteria (methodological index for nonrandomized studies) were used to assess the quality of articles.

RESULTS

A total of 350 articles were identified, 9 of which met final inclusion criteria for qualitative analysis. Outcomes defined in each publication were highly varied and relied on several unstandardized measures. The most commonly reported treatment option was topical nasal steroids, although overall there was limited evidence on which to base treatment recommendation.

CONCLUSIONS

There is not adequate evidence to develop a standardized treatment protocol for RM. The development of a uniform questionnaire, standard outcomes to be measured, and a method of assessing such outcomes is necessary. Prospective randomized controlled studies are warranted to determine the optimal treatment regimen following diagnosis of RM.

Modulation of the ultradian human nasal cycle by sleep stage and body position

Objective:

The nasal cycle, which is present in a significant number of people, is an ultradian side-to-side rhythm of nasal engorgement associated with cyclic autonomic activity. We studied the nasal cycle during REM/non-REM sleep stages and examined the potentially confounding influence of body position on lateralized nasal airflow.

Methods:

Left- and right-side nasal airflow was measured in six subjects during an eight-hour sleep period using nasal thermistors. Polysomnography was performed. Simultaneously, body positions were monitored using a video camera in conjunction with infrared lighting.

Results:

Significantly greater airflow occurred through the right nasal chamber (relative to the left) during periods of REM sleep than during periods of non-REM sleep (p<0.001). Both body position (p < 0.001) and sleep stage (p < 0.001) influenced nasal airflow lateralization.

Conclusions:

This study demonstrates that the lateralization of nasal airflow and sleep stage are related. Some types of asymmetrical somatosensory stimulation can alter this relationship.

Evaluation of the effect of nasal dorsal skin cooling on nasal mucosa by acoustic rhinometry

BACKGROUND

The use of cold nasal packs on the nose and nape of the neck is currently recommended for patients with epistaxis as this is thought to induce reflex nasal vasoconstriction, which decreases the bleeding. There have been a few investigations on the effect of cold compress application to the nose, but none of these focused specifically on nasal cooling of the skin of the nose.

METHODS

Acoustic rhinometry was performed to obtain baseline measurements. Nasal dorsal skin was then cooled with two ice packs that were held on the left and right side of the nose for a total of 10 minutes by the subjects. The rhinometry measurements were taken at the time of initial application (baseline), and after 5 and 10 minutes of ice pack application.

RESULTS

Comparisons of the first and second minimal cross-sectional area values, and total nasal cavity volume measurements revealed no statistical differences.

CONCLUSION

The results of this study indicate that one should be sceptical about the efficiency of cold compress application, which is frequently used in clinical practice in cases with epistaxis.

Diagnostic value of outcome measures following allergen exposure in an environmental challenge chamber compared with natural conditions

BACKGROUND

Efficacy testing of drugs in seasonal allergic rhinitis (SAR) is often disturbed by seasonal variations of environmental allergens, and assessment of onset and duration of action is hardly possible under natural conditions. Allergen provocation in an environmental challenge chamber (ECC) can be of added value in this respect. However, the specificity, sensitivity, and reproducibility of outcome measures under both settings are unclear.

OBJECTIVE

The aim of this study was to investigate and compare the diagnostic value (specificity, sensitivity, and reproducibility) of clinical end-points and biomarkers both following allergen provocation in an ECC and under natural conditions.

METHODS

Sixty adult patients with SAR to grass and 60 healthy subjects were exposed twice to grass pollen in an ECC and observed twice during the pollen season. Symptoms, nasal flow, as well as exhaled and nasal nitric oxide (NO) were investigated.

RESULTS

The total nasal symptom score (TNSS) in the ECC had the best reproducibility (intraclass correlation coefficient ICC=0.86) and sensitivity/specificity [area under receiver operating characteristic curve (AUC)=0.99] of all measures. Symptoms in season also had good sensitivity/specificity but were far less reproducible. Nasal flow in the ECC had good sensitivity/specificity but reproducibility was limited. NO measurements showed good reproducibility but sensitivity/specificity were limited, except for exhaled NO in season (AUC=0.75).

CONCLUSION

The high reproducibility and sensitivity/specificity in the ECC suggests that TNSS is a valuable outcome measure. While exhaled NO can be considered to monitor airway inflammation, nasal NO appears to be unspecific.

Validation of a cadaveric model for comprehensive physiologic and anatomic evaluation of rhinoplastic techniques

BACKGROUND

The physiologic effects of specific rhinoplasty maneuvers are incompletely understood, largely because of a limited ability to objectively examine such interventions. The purpose of this study was to develop and validate a cadaveric model for rhinoplasty testing.

METHODS

Ten cadaver heads were methodically prepared to simulate ventilatory conditions. Airway dimensions were measured with three-dimensional computed tomography and acoustic rhinometry. Airflow, pressure, and resistance were measured under conditions of both inhalation and exhalation. Resistance was determined using active anterior rhinomanometry and a continuously variable pressure gradient. Anatomic and physiologic properties were first compared against normative data. Measurements were then taken after application of an adhesive external midvault dilator (BreatheRight; GlaxoSmithKline).

RESULTS

The average minimal cross-sectional areas by acoustic rhinometry and by computed tomography were 0.87 cm2 and 0.84 cm2 per nostril, respectively (n = 20). The average distance from the nostril to the internal nasal valve was 1.7 cm by acoustic rhinometry and 1.5 cm by computed tomography, consistent with published in vivo normative data at the internal nasal valve. The average resistance with simulated exhalation closely approximated known normative values. With the application of the adhesive nasal dilator, the average area (acoustic rhinometry) increased by 50 percent at the internal nasal valve. During inhalation, the resistance decreased by 21 percent following application of the adhesive dilator.

CONCLUSIONS

The model provides an accurate representation of nasal anatomy and physiology suitable for objective analysis of rhinoplasty maneuvers. The objective modalities used herein may be applied to rhinoplasty study using this model with accuracy and reproducibility. The external dilator increased area at the internal valve (minimal cross-sectional area) and decreased resistance.

Low temperature results in decreased tension in decellularized human nasal mucosa

BACKGROUND

Cooling may induce nasal obstruction. In our previous study, we showed low temperature induced a rapid relaxation of isolated human nasal mucosa and it was independent of vasoconstriction. The aim of this study was to elucidate the mechanism responsible for such findings.

METHODS

Nasal mucosa strips were prepared from inferior turbinate samples. Decellularization of human nasal mucosa was achieved by treatment with sodium dodecyl sulfate 0.1% for 15 hours at 37 degrees C in a shaking water bath. Then, the effect of cooling (37-10 degrees C) on the isometric tension change of decellularized nasal mucosa was evaluated. In addition, the presence of elastic fibers within the nasal mucosa was identified in both histological section and scanning electron microscope.

RESULTS

Results indicated cooling induced a relaxation response of isolated decellularized human nasal mucosa and it was similar to that of intact nasal mucosa. The elastic fibers formed in wavy lines and were distributed throughout the submucosal layer.

CONCLUSION

Cooling induced a similar relaxation response both in the absence or in the presence of cellular components in isolated human nasal mucosa, suggesting that this response is mediated by the abundant extracellular matrix.

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.

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.