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

Traditional Nostril Yoga Breathing Practices and Oxygen Consumption: A Randomized, Cross-over Study

Background

Traditional yoga texts describe "cross nostril breathing," with inhalation and exhalation through different nostrils. Previous research reported no clear differences in oxygen consumption during uninostril breathing (i.e., inhalation and exhalation through the same nostril), hence not supporting right and left uninostril breathing as activating or relaxing, respectively, with no research on oxygen consumed in "cross nostril breathing."

Methods

Oxygen consumed during "cross nostril breathing" was measured in healthy participants (n = 47, males, 26.3 ± 6.4 years). Five sessions (viz., right nostril inspiration yoga breathing [RNIYB], left nostril inspiration yoga breathing [LNIYB], alternate nostril yoga breathing [ANYB], breath awareness (BAW), and quiet rest (QR) were conducted on separate days in random order. Sessions were 33 min in duration with pre, during, and post states.

Results

Volume of oxygen consumed (VO2) and carbon dioxide eliminated (VCO2) increased during RNIYB (9.60% in VO2 and 23.52% in VCO2), LNIYB (9.42% in VO2 and 21.20% in VCO2) and ANYB (10.25% in VO2 and 22.72% in VCO2) with no significant change in BAW and QR. Diastolic blood pressure decreased during BAW and QR and after all five sessions (P < 0.05; in all cases). All comparisons were with the respective preceding state.

Conclusion

During the three yoga breathing practices, the volume of oxygen consumed increased irrespective of the nostril breathed through, possibly associated with (i) conscious regulation of the breath; (ii) attention directed to the breath, and (iii) "respiration-locked cortical activation." Restriction of the study to males reduces the generalizability of the findings.

Correlations between objective and subjective tests of nasal patency in patients undergoing septoplasty

OBJECTIVE

This study assessed correlations between pre- and post-operative objective and subjective nasal patency test results in patients undergoing septoplasty to treat nasal septum deviation.

METHOD

Eighty nasal septum deviation patients who underwent septoplasty were prospectively enrolled. Nasal Obstruction Symptom Evaluation questionnaire scores, anterior rhinomanometry and acoustic rhinometry data were compared pre-operatively and three months after surgery. The left, right and total volume and left, right and total minimum cross-sectional area acoustic rhinometry values were compared.

RESULTS

The left volume, total volume, left minimum cross-sectional area and total minimum cross-sectional area differed significantly between the two time-points (all p < 0.05). The total resistance, inspiratory total airflow, expiratory total resistance and expiratory total airflow rhinomanometric data did not differ between the two timepoints (all p > 0.05).

CONCLUSION

This study suggested that subjective tests such as the Nasal Obstruction Symptom Evaluation questionnaire are optimal to identify complaints and assess post-operative satisfaction.

Gender Differences in Nasal Anatomy and Function Among Caucasians

Background: Anatomical variations influence nasal physiology, yet sex differences in physiology remains unclear. Objective: To investigate sex differences among Caucasians using computational fluid dynamics. Methods: Adult subjects were selected with normal nasal cone beam computed tomography (CBCT) images and Nasal Obstruction Symptom Evaluation scores ≤30. The CBCT images were used to create subject-specific airway models. Nasal surface area (SA) and volume were computed, and airflow and heat transfer were simulated. Results: The CBCT scans were taken from 23 females and 12 males. The SA and volume (males: mean = 25.0 cm3; females: mean = 19.5 cm3; p < 0.001; Cohen's d = 1.51) were significantly larger for males, but SA-to-volume ratio did not differ significantly. Although unilateral nasal resistance did not vary greatly, females had higher bilateral resistance (males: mean = 0.04 Pa.s/mL; females: mean = 0.05 Pa.s/mL; p = 0.044; Cohen's d = 0.37). Females had higher heat flux (males: mean = 158.5 W/m2; females: mean = 191.8 W/m2; p = 0.012; Cohen's d = 0.79), but males had larger SA where mucosal heat flux exceeds 50 W/m2. Conclusions: These findings suggest differences in normal nasal anatomy and physiology between Caucasian males and females, which may be useful when assessing sex-specific functional outcomes after nasal surgery.

The role of normal nasal morphological variations from race and gender differences on respiratory physiology

This study identifies anatomical and airflow-induced relationships based on nasal morphological variations due to inter- and intra-racial differences and gender. Subject-specific nasal airway reconstruction was created from computed tomography images in 16 subjects: 4 subjects from each ethnic group (Black, East Asian, Caucasian, and Latino) comprising of 2 males and 2 females. Volume, surface area and nasal index were calculated, as well as airflow rate and nasal resistance after computational fluid dynamics simulations in the nasal airway. Results showed that nasal airspace surface area (p = 0.0499) and volume (p = 0.0281) were significantly greater in males than in females. Nasal volume was greatest in East Asians (Median = 20.38cm³, Interquartile Range [IQR] = 4.58 cm³), Latinos had the greatest surface area (Median = 219.70cm², IQR = 29.56cm²). On average, East Asian and Black females had larger nasal index than their male counterparts. Caucasians had the highest median nasal resistance (0.050 Pa.s/mL, IQR = 0.025 Pa.s/mL). Results indicate that there exist anatomical variabilities based on race and gender. However, these variabilities may not significantly influence nasal function.

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

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Re-evaluating the nasal cycle by long-term rhinoflowmetry: most individuals demonstrate a 'mixed' nasal cycle

BACKGROUND

The nasal cycle seems to be more complex than a strictly alternating swelling of the nasal mucosa. Long-term rhinoflowmetry (LRFM) allows continuous investigation of changes in nasal airflow over 24 hours (24h). We evaluated the various types of nasal cycle with LRFM over 24 hours and investigated the influence of age and gender.

METHODS

LRFM was continuously performed over 24h in 55 rhinologically healthy subjects (36 female, 19 male). The LRFM flow curves were examined for phases of the 'classical' 'in-concert' 'one-side' and'no-cycle' cycle types. Subjects were divided into 4 age subgroups (19-29; 30-49; 50-69; >70 years). Correlations of age and gender with the individual cycle forms were analyzed.

RESULTS

85.5% of the subjects presented a 'mixed' nasal cycle within 24h. 'classical' nasal cycle was seen most often (92.7% vs. 'in-concert' 56.4% vs. 'one-sided' 18.2% vs. 'no-cycle' 5.5%). Older age groups significantly more often presented the 'no-cycle' type. A tendency was seen towards a mixed nasal cycle with increasing age. The mixed nasal cycle was significantly more often seen in the female subjects.

CONCLUSIONS

LRFM is an easy-to-use measurement tool. The 'mixed' nasal cycle predominates. However, all 4 different cycle types can be detected, alternating over 24h in each subject. Moreover, the cycle type varies with age.

The effect of decongestion on nasal airway patency and airflow

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

Three-Dimensional Measurements in Assessing the Results of Inferior Turbinate Surgery

Objectives:

Acoustic rhinometry is widely used in evaluating patients with nasal congestion, but it only has a partial correlation with patient symptoms. The use and focus of cone beam computed tomography (CBCT) scans are mainly on the paranasal sinuses and less on the nasal cavities. Therefore, information acquired from CBCT scans is not used to its full extent. In our present study, we have studied patients with enlarged inferior turbinates. Our aim was to investigate and compare the use of 3D volumetric measurements and cross-sectional area measurements taken from CBCT scans to results obtained from acoustic rhinometry.

Material and methods:

In total, 25 patients with enlarged inferior turbinates were studied. CBCT scans were obtained preoperatively and at twelve months postoperatively. 3D volumetric and cross-sectional area measurements were compared to results from acoustic rhinometry, the visual analogue scale (VAS) and Glasgow Health Status Inventory (GHSI) questionnaires.

Results:

A statistically significant change in 3D volume and cross-sectional area was measured in the anterior part of the inferior turbinate and surrounding air space after inferior turbinate surgery. VAS and GHSI results had mild correlations with the 3D volume and cross-sectional area measurements of the anterior part of the inferior turbinate. Acoustic rhinometry correlated with the air space 3D volume measurements in the anterior part.

Conclusions:

Fully utilized CBCT scans provide more comprehensive and accurate information. Furthermore, 3D analysis of the inferior turbinates provides valuable information and more precise measurements compared to acoustic rhinometry.

Short-term and long-term effects of rapid maxillary expansion on the nasal soft and hard tissue

OBJECTIVES

To evaluate nasal soft and hard tissue changes immediately post-rapid maxillary expansion (RME) and to assess the stability of these changes using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 35 treatment group (TG) patients (18 girls, 17 boys; 9.39 ± 1.4) had a pre-RME CBCT and a post-RME CBCT approximately 66 days after expansion, and 25 patients had a follow-up CBCT 2.84 years later. A total of 28 control group (CG; no RME) patients (16 girls, 12 boys; 8.81 ± 1.6) had an initial CBCT and a CBCT an average of 2.25 years later. Soft and hard tissue nasal landmarks were measured in transverse, sagittal, and coronal planes of space on CBCT scans. Differences within the same group were evaluated by paired t-tests or Wilcoxon signed-rank tests. Long-term comparisons between TG and CG were evaluated by independent-sample t-tests or Wilcoxon rank-sum tests.

RESULTS

Immediately post-RME, there were statistically significant mean increases of 1.6 mm of alar base width, 1.77 mm of pyriform height, and 3.57 mm of pyriform width (P < .05). CG showed the significant increases over 2.25 years (P < .001). Compared with CG, the long-term evaluation of TG demonstrated only pyriform height and pyriform width showed a statistically significant difference (P < .01).

CONCLUSIONS

Although RME produced some significant increase on the nasal soft tissue immediately after expansion, it regressed to the mean of normal growth and development over time. However, long-term evaluation of TG compared with CG showed only pyriform height and pyriform width to be affected by RME.

Investigating the nasal cycle using unilateral peak nasal inspiratory flow and acoustic rhinometry minimal cross-sectional area measurements

OBJECTIVE

To plot the nasal cycle using unilateral peak nasal inspiratory flow (UPNIF) and unilateral minimal cross-sectional area (UMCA) readings demonstrating a linear relationship in normal nasal function. Additionally, to determine how this changes in abnormal nasal function.

DESIGN

A cross-sectional study measuring UPNIF and UMCA in controls demonstrating normal nasal function and in patients with nasal obstruction.

SETTING

Royal National Throat Nose and Ear Hospital, London.

PARTICIPANTS

A total of 39 participants, 26 controls and 13 patients, were recruited. Controls exhibited normal nasal function with SNOT-22 <5. Patients nasal obstruction symptoms secondary to inflammation or structural abnormality with SNOT-22 >9.

MAIN OUTCOME MEASURES AND RESULTS

Airflow rates and resistance values were derived from UPNIF and UMCA measurements respectively based on Poiseuille's laws. Ratios between right and left UPNIF and UMCA values were taken to adjust for confounding factors. The relationship of 1/Resistance Ratio and Airflow Rate Ratio demonstrated a linear of direct proportionality of strong correlation and statistical significance (correlation coefficient = 0.76, P « 0.01). This suggests that data points from controls with a normal nasal cycle lie closely along the regressed line, whilst those lying significantly away were shown to belong to patients with nasal dysfunction. Olfactory dysfunction appears to be a sensitive discriminator in predicting this.

CONCLUSION

This study demonstrates the directly proportional relationship of 1/Resistance Ratio and Airflow Rate Ratio in normal nasal function. Furthermore, nasal pathology can be predicted if data points lie significantly outside these normal limits. Further studies are needed to validate exact normal and abnormal thresholds.

A simple, quick, validated method of recording the nasal cycle in humans using a subjective scale

BACKGROUND

Studies on the nasal cycle can be limited by time-consuming rhinomanometric measurements. However, quantifiable subjective assessment of nasal airflow has been limited by poor correlation with rhinomanometric data, even when investigating patients with a deviated nasal septum.

METHODS

Thirty healthy participants attended two study days for rhinomanometric and subjective assessment of nasal airflow (using the subjective ordinal scale). A nasal partitioning ratio was calculated for both measures.

RESULTS

Objective and subjective nasal partitioning ratios were compared; strong correlations were seen, with a correlation coefficient of 0.64 (p &lt; 0.00001) on day 1 and 0.68 (p &lt; 0.00001) on day 2.

CONCLUSION

The use of the subjective ordinal scale and nasal partitioning ratio provides a sensitive tool for assessing relative nasal airflow, with results that correlate strongly with rhinomanometric data. This finding strongly suggests that this combination could be used for future subjective assessment of the nasal cycle.

Relationship between Subjective Nasal Stuffiness and Nasal Patency Measured by Acoustic Rhinometry

Nasal geometry measured by acoustic rhinometry was compared with the subjective sensation of nasal stuffiness in healthy subjects before and after provocation with histamine. The correlation was poor at rest, but it was significant after histamine provocation in children and adults. It is easier to find a relationship between subjective and objective nasal obstruction after inducing congestion.

Measuring and Characterizing the Human Nasal Cycle

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

The relationship between nasal resistance to airflow and the airspace minimal cross-sectional area

The relationship between nasal resistance (R) and airspace minimal cross-sectional area (mCSA) remains unclear. After the introduction of acoustic rhinometry, many otolaryngologists believed that mCSA measurements would correlate with subjective perception of nasal airway obstruction (NAO), and thus could provide an objective measure of nasal patency to guide therapy. However, multiple studies reported a low correlation between mCSA and subjective nasal patency, and between mCSA and R. This apparent lack of correlation between nasal form and function has been a long-standing enigma in the field of rhinology. Here we propose that nasal resistance is described by the Bernoulli Obstruction Theory. This theory predicts two flow regimes. For mCSA>Acrit, the constriction is not too severe and there is not a tight coupling between R and mCSA. In contrast, when mCSAAcrit (estimated to be 0.37cm(2)), this theory suggests that airway constrictions are rarely an exclusive contributor to nasal resistance, which may explain the weak correlation between mCSA and subjective nasal patency.

The effect of vibrissae on subjective and objective measures of nasal obstruction

BACKGROUND

Nasal congestion and/or obstruction represents a prevalent and extensively studied problem. No published research exists that describes the impact of nasal hair (vibrissae) on nasal obstruction.

OBJECTIVE

To assess the impact of nasal vibrissae on subjective and objective measurements of nasal obstruction.

METHODS

In this prospective study, 30 healthy participants without nasal symptoms were assessed for baseline vibrissae density and were treated with a topical decongestant. The subjects were then asked to subjectively assess nasal breathing by using four questions from the Nasal Obstruction Symptom Evaluation instrument before undergoing rhinomanometry. Nasal vibrissae were then trimmed, and the participants repeated the subjective and objective assessments. Pre- and postintervention outcomes, including symptom scores, nasal airflow, and resistance, were compared by using statistical analysis.

RESULTS

Statistically significant improvement was noted in subjects' nasal airway specific symptom scores and in objective measurements of their nasal airway. Patients with moderate or many vibrissae at baseline were noted to have greater likelihood of improvement in subjective and objective obstruction assessments than patients rated with few.

CONCLUSION

In these 30 subjects, statistically significant improvement occurred in both subjective and objective assessments of nasal obstruction, particularly in patients with greater density of vibrissae. These findings support further study of the potential benefit of the reduction of vibrissae density in some patients with nasal obstruction.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Assessment of nasal obstruction: correlation between subjective and objective techniques

BACKGROUND

Nasal sensation of airflow describes the perception of the passage of air through the nose. Nasal obstruction can be assessed using subjective techniques (symptom scores and visual analogue scales [VAS]) and objective techniques (anterior rhinomanometry [RMN], acoustic rhinometry [AR], and peak nasal inspiratory flow [PNIF]). Few studies have evaluated the correlation between these techniques.

OBJECTIVE

The primary objective of our study was to determine the degree of correlation between subjective and objective techniques to assess nasal obstruction.

MATERIALS AND METHODS

Nasal obstruction was assessed using a symptom score, VAS, RMN, AR (minimal cross-sectional area [MCSA] and volume), and PNIF in 184 volunteer physicians. Spearman's rho was recorded. Correlations were considered weak if r ≤ 0.4, moderate if 0.4 < r < 0.8, and strong if r > 0.8.

RESULTS

Mean (SD) age was 37.1 (6.9) years (range, 25-56 years); 61% were women. We found a strong correlation (r > 0.8; p = 0.001) between the different parameters of RMN and a moderate correlation between symptom score and VAS (r = 0.686; p = 0.001) and between MCSA and RMN (resistance) (r = 0.496; p = 0.001) and PNIF (r = 0.459; p = 0.001). The correlations were weak or non-significant for the remaining comparisons.

CONCLUSION

Nasal obstruction can be assessed using subjective and objective approaches. The correlations between objective techniques were moderate to strong. In addition, between subjective techniques we reported a moderate correlation. Finally, the correlations between the subjective and objective techniques were weak and absent. These findings suggest that each of the techniques assesses different aspects of nasal obstruction, thus making them complementary.

Assessment of nasal parameters in determination of olfactory dysfunction in Parkinson's disease

OBJECTIVES

To assess nasal cycle, nasal mucosal pH and mucociliary clearance time in patients with Parkinson's disease and healthy control subjects.

METHODS

Patients with idiopathic Parkinson's disease and healthy control subjects were recruited. Presence of the nasal cycle, nasal mucosa pH and mucociliary clearance time were investigated in all participants.

RESULTS

The study included 27 patients and 24 control subjects. The nasal cycle was present in significantly fewer patients than controls. Nasal pH and mucociliary clearance time were significantly higher in patients than in controls.

CONCLUSIONS

Parkinson's disease is associated with alterations in nasal cycle, nasal mucosa pH and mucociliary clearance time. Measurements of these nasal parameters may be useful for the early diagnosis of autonomic and olfactory dysfunction in Parkinson's disease.

Allergic rhinitis with negative skin tests

Recently, several studies have revealed a subset of patients who have positive nasal provocation to allergens despite having a negative skin prick test. It has been hypothesized that these patients have localized allergic rhinitis. However, the prevalence varies greatly, ranging from 0% to 100% of skin test-negative individuals. This wide range in prevalence is likely related to differences in methodology, including differences in allergen manufacturers, concentrations, and numbers of allergens tested and, perhaps most importantly, criteria for a positive nasal challenge. Despite the evidence to date, many challenges exist with regard to the concept of localized nasal allergy. Further studies will be required to further define the immunopathology, prevalence, practical diagnostic tests, and management.

Diagnostic tools in Rhinology EAACI position paper

This EAACI Task Force document aims at providing the readers with a comprehensive and complete overview of the currently available tools for diagnosis of nasal and sino-nasal disease. We have tried to logically order the different important issues related to history taking, clinical examination and additional investigative tools for evaluation of the severity of sinonasal disease into a consensus document. A panel of European experts in the field of Rhinology has contributed to this consensus document on Diagnostic Tools in Rhinology.

Correlation between subjective and objective evaluation of the nasal airway. A systematic review of the highest level of evidence

BACKGROUND

There is no consensus about the value of objective measurements of nasal patency.

OBJECTIVE

To assess the correlation between the subjective sense of nasal patency and the outcomes found with rhinomanometry and acoustic rhinometry.

TYPE OF REVIEW

Structured literature search. SEARCH STRATEGY AND EVALUATION METHOD: Review of English-language articles in which correlations were sought between subjective nasal patency symptoms and objective scores as found with rhinomanometry [nasal airway resistance (NAR)] and acoustic rhinometry [minimal cross-sectional area (MCA)]. Correlations were related to unilateral or combined assessment of nasal passages and to symptomatic nasal obstruction or unobstructed nasal breathing.

RESULTS

Sixteen studies with a level of evidence II-a or II-b fit the inclusion criteria and were further analysed. Almost every possible combination of correlations or lack thereof in relation to the variables included was found. However, when obstructive symptoms were present, a correlation between the patency symptoms with nasal airway resistance and minimal cross-sectional area was found more often than in the absence of symptoms. In cases of bilateral assessment a correlation was found almost as often as it was not between patency symptoms and total nasal airway resistance or combined minimal cross-sectional areas, while in the limited amount of studies in which unilateral assessment was done a correlation was found each time between patency symptoms and nasal airway resistance.

CONCLUSIONS

The correlation between the outcomes found with rhinomanometry and acoustic rhinometry and an individual's subjective sensation of nasal patency remains uncertain. Based on this review, it seems that the chance of a correlation is greater when each nasal passage is assessed individually and when obstructive symptoms are present. There still seems to be only a limited argument for the use of rhinomanometry or acoustic rhinometry in routine rhinologic practice or for quantifying surgical results.

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.

Modified Glatzel mirror test reproducibility in the evaluation of nasal patency

The Glatzel Mirror (GM) is used to evaluate nasal patency. Validation studies are not available in the literature. This paper aims to verify the GM test reproducibility and the correlation between the intra-subject condensation area and nasal patency subjective perception.

Methods

This is a prospective study. 25 subjects were evaluated with the GM for five consecutive minutes, every half an hour for 4 hours; every day, beginning in the early afternoon, every Thursday for five consecutive weeks. A visual analogue scale was used to evaluate nasal patency perception in all periods.

Results

The total correlation coefficient (right + left areas) found between the condensation area and the subjective perception was r = 0.04 (p = 0.37). On the left side it was r = 0.08 (p = 0.09) and on the right side r = 0.05 (p = 0.28). The mean unilateral variation coefficient was less than 15% and the total was less than 12%, regardless of the time period interval between test and re-test.

Conclusion

We did not observe any significant correlation between the subjective perception of breathing and the condensation area. Unilateral variability was higher than the total (right + left area) and the test variability was the same between the different time periods of measurements.

Evidence-based recommendations regarding the differential diagnosis and assessment of nasal congestion: using the new GRADE system

Nasal congestion is an important symptom in nasal pathology and can be defined as an objective restriction of nasal cavity airflow because of mucosal pathology and/or increased mucus secretion (excluding anatomical variants). Using the new Grading Recommendations Assessment, Development and Evaluation system, evidence-based recommendations are made that will encompass different clinical questions regarding diagnostic modalities of nasal congestion: (i) their usefulness in assessment of presence and severity of congestion; (ii) their usefulness in assessment of etiological pathology responsible for congestion; and (iii) their usefulness in follow up and treatment effectiveness evaluation of nasal congestion.

A reprodutibilidade do espelho de Glatzel modificado na aferição da permeabilidade nasal

O espelho de Glatzel (EG) é utilizado para a avaliação da permeabilidade nasal. Estudos de validação inexistem na literatura. Este estudo teve por objetivos verificar a reprodutibilidade do EG e a correlação intra-sujeito entre área de condensação e percepção subjetiva de permeabilidade nasal. MÉTODOS: Estudo prospectivo onde 25 sujeitos foram avaliados com o EG por cinco minutos consecutivos; cada meia hora por quatro horas; cada dia no início da tarde, por cinco dias e toda a quinta-feira por cinco semanas consecutivas. Utilizou-se uma escala analógica visual para avaliar a percepção de respiração nos períodos. RESULTADOS: O coeficiente de correlação total (área direita mais esquerda) encontrado entre área de condensação e percepção subjetiva foi de r=0,04 (p=0,37). No lado esquerdo foi de r=0,08 (p=0,09) e no lado direito de r=0,05 (p=0,28). Os coeficientes de variação unilaterais medianos foram menores que 15% e os totais menores que 12%, independente do intervalo de tempo entre teste e re-teste. CONCLUSÃO: Não se evidenciou correlação significativa entre a percepção subjetiva e a área de condensação. A variabilidade unilateral foi maior do que quando considerados os valores totais (direito mais esquerdo) e não houve diferença na variabilidade das medidas de área de condensação nasal nos diferentes momentos do tempo.

Bilateral nasal allergen provocation monitored with acoustic rhinometry. Assessment of both nasal passages and the side reacting with greater congestion: relation to the nasal cycle

BACKGROUND

The effect of bilateral nasal provocation on nasal mucosa measured with the use of acoustic rhinometry (AR) can be assessed for both nasal passages or for the side responding with greater congestion. Assessment of changes in nasal congestion during the nasal provocation test (NPT) can be affected by the nasal cycle (NC). The aim of this study was to find out the most accurate method to evaluate changes observed during bilateral nasal provocation.

METHODS

Cross-sectional areas (CSA) at the level of inferior nasal turbinate (CSA-2) were recorded by AR in 26 volunteers with allergic rhinitis during the NC for 5-7 h and subsequently during NPT. The risk of spontaneous total and unilateral CSA-2 decrease was established. Sensitivity of the NPT assessment for the total CSA-2 and for the side responding with greater congestion was evaluated at chosen thresholds. These thresholds were selected in a way that the risk levels of spontaneous decrease of unilateral and total CSA-2 were equal.

RESULTS

The assessment of the total CSA-2 was found to be more sensitive than the assessment of the side responding with greater congestion. The highest sensitivity and specificity of the test was achieved by using a combination of both assessments. Optimum thresholds of the CSA-2 decrease for assessment at 15 min after provocation, with this method, were 27% and 40% for the side responding with greater congestion and for the total CSA-2, respectively.

CONCLUSIONS

Recognition of the risk of spontaneous unilateral and total CSA-2 decreases enables introduction of combined assessment of bilateral NPT. This assessment seems to be the most accurate method for evaluation of the test results.

A Comparison of Skin Endpoint Titration and Skin-Prick Testing in the Diagnosis of Allergic Rhinitis

Among the many methods of allergy diagnosis are intradermal testing (IDT) and skin-prick testing (SPT). The usefulness of IDT has been called into question by some authors, while others believe that studies demonstrating that SPT was superior might have been subject to bias. We conducted a study to compare the validity of SPT and IDT—specifically, the skin endpoint titration (SET) type of IDT—in diagnosing allergic rhinitis. We performed nasal provocation testing on 62 patients to establish an unbiased screening criterion for study entry. Acoustic rhinometric measurements of the nasal responses revealed that 34 patients tested positive and 28 negative. All patients were subsequently tested by SET and SPT. We found that SPT was more sensitive (85.3 vs 79.4%) and more specific (78.6 vs 67.9%) than SET as a screening procedure. The positive predictive value of SPT was greater than that of SET (82.9 vs 75.0%), as was the negative predictive value (81.5 vs 73.0%). None of these differences was statistically significant; because of the relatively small sample size, our study was powered to show only equivalency. The results of our study suggest that the information obtained by the SET method of IDT is comparable to that obtained by SPT in terms of sensitivity, specificity, and overall performance and that both SET and SPT correlate well with nasal provocation testing for ragweed. Therefore, the decision as to which to use can be based on other factors, such as the practitioner's training, the desire for quantitative results, the desire for rapid results, and the type of treatment (i.e., immunotherapy or pharmacotherapy) that is likely to be chosen on the basis of test results.

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

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

Assessment of Nasal Cycle by Acoustic Rhinometry and Rhinomanometry

OBJECTIVE: We sought to investigate the pattern, duration, and amplitude of nasal cycle and its response to nasal decongestant.

STUDY DESIGN AND SETTING: Ten adult volunteers attended 2 sessions (with and without nasal spray of 0.1% xylometazoline) for consecutive examinations by rhinomanometry and acoustic rhinometry every 10 minutes over 6 hours.

RESULTS: A spontaneous fluctuation in nasal minimum cross-sectional area, volume, and nasal resistances (inspiration and expiration) could be observed in every consecutive measurement. A significant negative correlation ( r = −0.33 to −0.70, P < 0.05) between both nasal passages was shown in 5 subjects by rhinomanometry and in 2 subjects by acoustic rhinometry but was not detectable after nasal spray with 0.1% xylometazoline.

CONCLUSION: A spontaneous fluctuation in nasal patency can be documented every 10 minutes with irregular pattern, frequency, and amplitude. Classic nasal cycle is not a universal phenomenon, which can be abolished by the application of decongestant.

Risk factors for epistaxis during nasotracheal intubation

We performed a study to confirm which risk factors are significantly associated with epistaxis during nasotracheal intubation. One hundred patients who underwent nasotracheal intubation were included. Risk factors for epistaxis were analysed using the multiple logistic regression analysis with stepwise variable selection method. Epistaxis was most likely to occur if transit of the tube through the nasal passage was difficult (P=0.0001, odds ratio 625, 95% confidence interval 3.14-14.26). On the other hand, age and gender, obesity, smoking, tube size, repeated attempts of intubation, and intubation performed with the aid of Magillforceps were not significantly related with risk of epistaxis. The presence of nasal anatomical abnormalities also did not correlate significantly with epistaxis. Strategies to ensure smooth transit of the tube through the nasal passageways are essential to reduce the incidence of epistaxis.

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.

Elevation of nasal mucosal temperature increases the ability of the nose to warm and humidify air

The nose functions to warm and humidify inspired air. The factors that influence these functions have been studied to a limited degree. We have developed a method for measuring the temperature and relative humidity of the air before and after nasal conditioning to study nasal function. In this experiment we studied the effects of raising the mucosal surface temperature by immersion of the feet in warm water. Six subjects (avg. age = 27.0 years) were randomized to immersion of the feet in 30 degrees C and 40 degrees C water. The nasal mucosal temperature increased significantly from the 32.2+/-1.3 degrees C during immersion in the 30 degrees C water to the 33.1+/-1.2 degrees C during immersion in 40 degrees water (p < 0.05). No significant difference in nasal volume was noted between the 30 degrees (17.8+/-4.5 cc) and the 40 degrees (17.7+/-5.3 cc) immersions. There was a significant increase in the conditioning capacity of the nose (as measured by total water content of inspired air) in response to cold-air challenge during the 40 degrees immersion (1669+/-312 mg water) when compared to the 30 degrees immersion (1324+/-152 mg water). From these data we deduce that warming of the nasal mucosa improves the ability of the nose to condition inspired air without a significant change in the volume of the nasal cavity.