The role of rhinomanometry, acoustic rhinometry, and mucociliary transport time in the assessment of nasal patency.

Desiderio pass[grave{a}]li

Giulio Cesare Pass[grave{a}]li

Abstract

We conducted a study of 60 patients with different nasal pathologies who complained of nasal obstruction. Our goal was to evaluate the reliability of rhinomanometry, acoustic rhinometry, and the measurement of mucociliary transport time in helping make the diagnosis of nasal pathologies. We also sought to discover whether there is a correlation between the findings of these objective tests and the results of patients' own subjective assessments of nasal obstruction. We found that acoustic rhinometry was more specific and more sensitive than rhinomanometry in diagnosing rhinopathies in patients with structural anomalies. Symptom scores as rated by patients on the visual analog scale frequently did not correlate with objective measures, as patients often overestimated the severity of their obstruction. However, for a few patients, there was a correlation between symptom scores and mucociliary transport times.

Introduction

Nasal obstruction is a common symptom in both acute and chronic nasal pathologies. The subjective evaluation of this symptom is marked by great variability, as patients often find it difficult to describe the sensation they feel. For this reason, Eccles proposed the use of a visual analog scale to quantify the severity of obstruction. [1] Patients rate the degree of their patency or blockage on a scale of 0 (completely patent) to 10 (completely blocked). Some studies have shown a good correlation between the subjective data obtained from the visual analog rating and objective data obtained from acoustic rhinometry. [2]

The aim of our study was to evaluate the reliability of rhinomanometry, acoustic rhinometry, and the measurement of mucociliary transport time (MCTt) in helping make the diagnosis of nasal pathologies. We also sought to discover whether there is a correlation between the subjective assessment of nasal obstruction and objective parameters (partial and total nasal resistance, right and left nasal volumes) in patients with rhinopathies of different etiologies.

Patients

We studied three groups of 20 patients; all 60 patients had complained of nasal obstruction. The three groups were distinguished by the type of nasal pathology that was diagnosed in each member of the group.

Group A. These patients had structural anomalies, such as a deviated septum or an irreversible hypertrophy of the inferior turbinate as revealed by a negative nasal decongestion test.

Group B. These patients were affected by seasonal or perennial allergic rhinitis, which had been diagnosed on the basis of the medical history, the clinical picture, or a positive response to an allergy test. The allergy assays included a prick test (level I), a radioallergosorbent test (level II), and a specific nasal provocation test (level III).

Group C. These patients had been diagnosed with nonspecific vasomotor rhinopathies. This was a diagnosis of exclusion, as patients had a positive nasal decongestion test but a negative allergy test.

All three groups were homogenous with regard to sex, age, and level of education. Patients were not in an acute phase of their pathology, and none had taken pharmacologic therapy of any type during the 2 weeks prior to the study. We were thus able to obtain objective and subjective assessments of their pathology during a "status" phase.

Materials and methods

All patients underwent an evaluation of nasal function by active anterior rhino-manometry, acoustic rhinometry, and measurement of the MCTt.

Rhinomanometry. Active anterior rhinomanometry was performed with a Menfis Rhino System device. All patients wore a face mask during the test to prevent distortion of the nostrils and nasal valve during the test. Measurements were taken in accordance with the standards set by the International Committee on Standardization of Rhinomanometry.[3] Nasal resistance was expressed at a pressure of 150 Pa.

Rhinometry. Acoustic rhinometry was performed with a Stimotron Rhinoklack RK 1000. To reduce variations in results related to the degree of angulation between the probe and the nasal cavities in different anatomic planes, we used an ophthalmologic-type craniostat that we had modified to suit our needs. This craniostat allowed us to exactly position each patient's head in relation to the rhinometer. With this method, which we call "positioned acoustic rhinometry," we were able to reduce the number of errors caused by the procedure itself.[4]

Transport time. MCTt was measured with an inert, colored tracer (charcoal powder) mixed with 3% saccharine. We swabbed a small quantity of the mixture onto the head of the inferior turbinate. Because the constituents of this mixture interact with nasal secretions in different ways, they allow a precise evaluation of how an insoluble medium (charcoal) and a soluble one (saccharine) behave in a fluid. The use of this mixture provided us with information on mucociliary function both objectively (via the appearance of the tracer on the posterior pharyngeal wall) and subjectively (the patient's sense of taste). Normal MCTt values in adults are 13 minutes (+/-3) for charcoal powder and 17 (+/-5) for saccharine; in children, they are 11 (+/-3) and 5 (+/-6) minutes, respectively.[5]

Visual analog rating. The subjective symptom score was obtained with a visual analog scale modified from Eccles' model (figure). Patients rated the perceived degree of their obstruction on a scale of 0 (complete patency) to 5 (complete stenosis). The scale also featured a gradation of color, from blue (patency) to red (stenosis).

Results

The variables we considered were age, sex, total inspiratory and expiratory nasal resistance, right and left nasal cavity volume, MCTt, and symptom score. Statistical analysis of the data was performed with the Student-Newman-Keuls procedure, which involves comparing the three groups of patients for all variables. The only statistically significant differences (p[less than]0.05) were found in groups B (allergic rhinitis) and C (nonspecific rhinitis) versus group A (structural anomalies) with regard to the mean inspiratory and expiratory nasal resistances measured on rhinomanometry (table 1). This finding indicates that nasal resistances are the most reliable parameter in patients with functional nasal pathologies such as rhinitis.

An "analysis of variance" was then performed by comparing the variables within each of the three groups. All patients in group A had significantly different values between right and left nasal volumes on rhinometry (p[less than]0.00l), as well as significantly different values between volume and age (p[less than]0.0l) (table 2). In both groups B and C, there were statistically significant differences (p[less than]0.00l) between the right and left nasal volumes (table 3).

It was not possible to measure statistically significant differences between symptom scores and objective parameters because of the small number of different scores, but discrepancies were frequently observed, as many patients had high symptom scores but normal resistance values and nasal volumes. However, in five patients (three with important septal deviation and two with nonallergic rhinitis), there was a positive correlation between delayed or blocked MCTt and high symptom scores.

Discussion

The results of this study prompt some interesting clinical observations. In group A, acoustic rhinometry was more specific and more sensitive than rhinomanometry in evaluating patency. This was confirmed by the significant correlation between the nasal volumes (left and right) and total nasal volumes and age in group A; in fact, nasal volumes physiologically change according to age, and acoustic rhinometry is able to detect these differences as well as any differences in partial nasal volumes in patients with structural anomalies.

In groups B and C, the measurement of nasal resistance by active anterior rhinomanometry was more reliable than acoustic rhinometry in evaluating nasal patency. This finding provides evidence that in patients with rhinitis, changes in respiratory parameters can be very evident if rhinomanometry is performed, even though the objective picture indicates an absence of significant morphologic change.

We frequently observed discrepancies between a patient's rating of symptoms on our visual analog scale and objective findings. When these discrepancies occurred, patients usually overestimated the severity of their obstruction. The reason for this exaggeration of symptoms was usually related to the psychological state of patients who focused their general anxiety on their nasal symptoms (somatization). However, in those cases when a positive correlation was observed between subjective sensation and MCTt, the overestimate of symptoms was simply the result of atrophy of the nasal mucosa. Atrophy can cause sensations that can mislead patients into believing there is obstruction even when there is complete patency. For example, atrophic nerve endings might not detect the feeling of airflow through the nose, leading the patient to believe that air is not flowing.

From the ENT Department, University of Siena Medical School, Siena, Italy.

Reprint requests: Prof. Desiderio Pass[grave{a}]li, ENT Department, University of Siena Medical School, V.le Bracci, 53100 Siena, Italy. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

References

(1.) Eccles R. Nasal airway resistance and nasal sensation of airflow. Rhinol Suppl 1992;14:86-90.

(2.) Yamagiwa M, Miyahara Y, Sakakura Y. Nasal sensation of airflow and nasal geometry evaluated by acoustic rhinometry. In: Passali D, ed. Rhinology Up-to-Date. Rome: Industria Grafica Romana, 1994:416-25.

(3.) Clement PA. Committee report on standardization of rhinomanometry. Rhinology 1984;22:151-5.

(4.) Passali D, Biagini C, Di Girolamo S, Bellussi L. Acoustic rhinometry: Practical aspects of measurement. Acta Otorhinolaryngol Belg 1996;50:41-5.

(5.) Passali D, Bellussi L, Bianchini Ciampoli M, De Seta E. Experiences in the determination of nasal mucociliary transport time. Acta Otolaryngol 1984;97:319-23.

       Comparison of the three groups of patients for all variables
                     (Student-Newman-Keuls procedure)
Group A   B  C   Mean
 A    -- -- -- 0.3470
 B    *  -- -- 0.4665
 C    *  -- -- 0.2865
(*.)p[less than]0.05
There were statistically significant differences in
groups B and C versus A with regard to inspiratory and
expiratory nasal resistances on rhinomanometry.
                     Comparison of variables in group
                         A by analysis of variance
          Age       AAR insp AAR exp AR right    AR left
Age        --          --      --     0.6483 [*] 0.6112 [*]
AAR insp   --          --      --       --         --
AAR exp    --          --      --       --         --
AR right 0.6483 [*]    --      --       --       0.6346 [+]
AR left  0.6122 [*]    --      --     0.6346 [+]   --
(*.)p[less than]0.01
(+.)p[less than]0.001
Significant differences were seen between
right and left nasal volumes on rhinometry
and between nasal volumes and age.
Key: AAR insp/exp = anterior active
rhinomanometry total inspiratory/expiratory
resistances; AR right/left = acoustic
rhinometry right/left nasal cavity volumes
                    Comparison of variables in groups B
                       and C by analysis of variance
         Age AAR insp AAR exp AR right    AR left
Age      --     --      --       --         --
AAR insp --     --      --       --         --
AAR exp  --     --      --       --         --
AR right --     --      --       --       0.6633 [*]
AR left  --     --      --     0.6633 [*]   --
(*.) p[less than]0.001
Significant differences were seen between
right and left nasal volumes on rhinometry.
Key: AAR insp/exp = anterior active
rhinomanometry total inspiratory/expiratory
resistances; AR right/left = acoustic
rhinometry right/left nasal cavity volumes.