The effect of methodology on the determination of nasal resistance

Confusion and controversy continue to characterize scientific understanding of the role that respiration plays in modifying growth. Identification of specific methods to provide valid measurement of nasorespiratory function can help clinicians to (1) make an informed judgment regarding postulated relationships between respiration and growth, (2) test the validity of a diagnosis of impaired nasal respiration or "mouth breathing," and (3) evaluate the efficacy of treatment for nasal obstruction. A method that has been frequently used to quantify nasorespiratory function is nasal resistance measurement or rhinomanometry. This investigation used a common form of this method, studying 25 adult subjects to examine the effect of a number of variables in methodology on nasal airway resistance values. Results indicate that resistance to nasally inspired air was not significantly different from resistance to nasally expired air. However, a significant difference in estimating resistance was found between airflow rates of 0.25 and 0.5 L/sec, with nasal resistance increasing at the higher flow rate. Determination of the method error indicated that the technique was reliable and accurate for the sample studied. It was found that both expansion of the anterior nares and use of a nasal decongestant spray produced a decrease in mean nasal resistance. The study emphasizes the need to standardize the method of determining nasal resistance in order to permit comparisons among studies, to obtain a more reliable estimate of resistance, and to identify the location of maximum constriction in the nasal airway.     

The effect of rapid maxillary expansion on nasal airway resistance

The purpose of this study was to evaluate changes in nasal resistance to airflow in persons undergoing rapid maxillary expansion and to reevaluate the responses at a 1-year follow-up. Nasal resistance measurements, assessed in four modes (natural state, anterior nares dilation with Tygon tubing, following administration of decongestant, and nares dilation with tubing and decongestant), were taken on a group of 38 patients receiving rapid maxillary expansion and compared with a control group not receiving expansion. Thirty-three of the patients were reevaluated 9 to 12 months after expansion was completed. Eighteen subjects in the control group were also reevaluated. Oral/nasal airflow rates (percent nasality) were recorded for the control group and for some of the expansion patients. Results indicated that some subjects receiving rapid maxillary expansion had a significantly higher nasal resistance than the control group. There was a significant median reduction in nasal resistance following rapid maxillary expansion, measured in the natural state only, and this appeared to be stable up to 1 year after maximum expansion was obtained. Rapid maxillary expansion appeared to effect an expansion at the anterior nares, which contributes to nasal resistance reduction. Individual variation in nasal resistance values was considerable and hence the median response for the group was not a reliable estimate of individual response. Due to the high individual response variability, rapid maxillary expansion is not a predictable means of decreasing nasal resistance.     

Association between nasal respiratory obstruction and vertical mandibular position

Vertical mandibular position is considered to have an effect on the patency of the upper airway, because mouth opening is associated with a backward and downward displacement of the mandible and tongue. This study was conducted to investigate the nature of mandibular displacement at rest and to determine whether or not different respiration modes and body postures influence the mandibular position. The mandibular position was measured by use of a newly developed system with magnets and magnetic sensors placed on the upper and lower first molars, respectively. Vertical mandibular position was significantly affected by the degree of nasal airway obstruction. The proportion of the duration of mouth opening from 0 to 2.5 mm was about 80% in the sitting and lateral recumbent positions and 55% in the supine position. The amount and duration of vertical mandibular displacement were thus significantly increased by experimentally induced nasal respiratory obstruction. Furthermore, it was demonstrated that the amount and duration of mouth opening were significantly greater in the supine posture than in the sitting and lateral recumbent positions. It is thus shown that nasal respiratory disturbance may be a key determinant for mouth opening and breathing and the resultant vertical mandibular displacement.     

The relationship between nasal airway size and nasal-oral breathing

Most clinicians agree that impaired nasal breathing results in obligatory mouth breathing. Some believe that mouth breathing influences dentofacial growth; others disagree. The term mouth breathing is confusing because total mouth breathing rarely occurs. A combination of nasal and oral breathing is more usual. The purpose of the present study involving 116 adult subjects was to (1) assess the relationship between nasal impairment and nasal-oral breathing, (2) determine the switching range from nasal to nasal-oral breathing, and (3) quantify the term mouth breathing. The pressure-flow technique was used to estimate nasal airway size; inductive plethysmography was used to assess nasal-oral breathing in normal and impaired breathers. Analysis of the date showed a Pearson rank correlation of 0.545 (P less than 0.001) between nasal area and nasal-oral respiration. Ninety-seven percent of subjects with a nasal size less than 0.4 cm2 were mouth breathers to some extent. About 12% of subjects with an adequate airway were assumed to be habitual mouth breathers. The findings indicate that the switching range from nasal to nasal-oral breathing is very narrow (0.4-0.45 cm2). These results also confirm our contention that in adults an airway less than 0.4 cm2 is impaired.     

Evaluation of nasal airway resistance during rapid maxillary expansion using acoustic rhinometry

The purpose of this study was to evaluate nasal airway resistance (NAR) during rapid maxillary expansion (RME) using acoustic rhinometry (AR). The sample comprised 22 children (13 girls and nine boys) with maxillary constriction. The mean age was 12.9 +/- 1.54 years and all patients were found to have normal nasal cavities following anterior rhinoscopic examination. A modified bonded splint type RME appliance was used for expansion. AR was used to measure NAR before (T1), during (T2) and after (T3) expansion, and at the end of retention (T4). Each AR recording was performed, for each patient, with and without the use of a decongestant. Subjective evaluation of reported changes in nasal breathing were also undertaken at T3. The results showed that NAR was significantly reduced with the use of RME, with the main decrease observed during expansion (P < 0.05). The use of a decongestant was not found to have any effect on the results. Subjective evaluation showed that 59 per cent of patients considered that their nasal breathing had improved following RME.     

A quantitative assessment of respiratory patterns and their effects on dentofacial development

The purpose of this study was to assess the effects of quantitatively determined breathing patterns on dentofacial development in growing children. Forty-nine subjects ranging in age from 10 to 16 years participated in the breathing pattern assessment portion of this project. Oral, nasal, and total airflow were measured at separate times by means of a head-out body plethysmograph technique and the values were compared with the subjects' and parents' subjective perceptions of their breathing modes. These breathing pattern measurements also were compared to nasal airway resistance and nasal power. Temporal variation and cyclic respiration, which may play important roles in quantitative evaluations of childrens' breathing patterns, also were addressed. In addition, objective assessments of possible associations between dentofacial structure and respiration were made on 45 of these children. Most subjects' exhibited was either an oronasal or a completely nasal respiratory pattern. However, significant variation in breathing measures was evident among a number of subjects whose breathing was measured twice on the same day and on different days. No significant correlations were found between objectively measured and subjectively determined impressions of respiratory patterns. In addition, there was no association between nasal airway resistance or nasal power and plethysmograph recordings of percent of mouth breathing. Comparisons of measured breathing modes and dentofacial characteristics revealed a weak tendency among mouth breathers toward a Class II skeletal pattern and retroclination of maxillary and mandibular incisors. In contrast, subjective perception of mouth breathing was associated with increased anterior facial height and greater mandibular plane angles. Nasal power and resistance were not correlated with either dental or skeletal variables. This study presents evidence that determination of respiratory pattern is a complex issue for which methods must be refined and performed longitudinally.     

Long-term follow-up after division of a pharyngeal flap for severe nasal obstruction.

Between 1965 and 1986, nine patients were noticed to have significant nasal airway obstruction following surgery for velopharyngeal incompetence (VPI). All had a superiorly based pharyngeal flap. Division of the flap was recommended to correct the posterior obstruction. A complete section of the flap was done in seven cases and lateral port enlargement was done in the remaining two. The interval between flap elevation and transection ranged from 5 months to 5 years. Three patients required more than one operation to fully correct the obstruction. All the patients were evaluated 2 to 14 years later to assess nasal breathing and speech and to document velopharyngeal function by nasoendoscopy and video-fluoroscopy. One patient presented major symptoms of nasal obstruction at follow-up, while other reported snoring and occasional mouth breathing, although their nasal respiration appeared subjectively adequate. Four patients had normal speech, three were mildly hyponasal, one was moderately hyponasal, and the other was severely hyponasal. Intelligibility was good in all cases but one, although three patients had some articulation errors: two with persistent errors related to early VPI and one from dental malocclusion and tongue protrusion. Videofluoroscopy and nasoendoscopy showed that despite complete transection at the base of the flap in eight cases, five still had evidence of residual tethering. In one patient, the obstruction was almost complete and repeat division of the flap was recommended. Seven patients showed increased thickness of the soft palate in the midline where the flap had been anchored.(ABSTRACT TRUNCATED AT 250 WORDS)     

Proposal for a screening questionnaire for detecting habitual mouth breathing,based on a mouth-breathing habit score

Background

When mouth breathing becomes habitual, it can cause sleep disorders and abnormal maxillofacial growth, thus early detection of habitual mouth breathing is important. We created a questionnaire for early detection of habitual mouth breathing using a score based on a spectrum of factors found to be characteristic of mouth breathers.

Methods

First, a draft 50-question questionnaire was given to 101 random dental clinic patients, classified by dental professionals into habitual mouth breathers (n?=?28) and nose breathers (n?=?73). The 10 questions that significantly differentiated mouth and nose breathers (p?<?0.05) were identified from this questionnaire. These questions, regarding nasal obstruction, open mouth at rest, awareness of mouth breathing, gum swelling and dental staining of the front teeth, bad breath, maxillary protrusion, nasal obstruction in childhood, bottle-feeding, and history of asthma, formed the basis for a second questionnaire. This second survey was completed by another 242 participants, separately classified into mouth breathing (n?=?26), suspected mouth breathing (n?=?40), and nose breathing groups (n?=?176).

Results

Receiver operating characteristic curve analysis of the resulting mouth breathing habit scores, representing the responses to the 10-question survey, showed moderate checklist diagnosability. Sensitivity of cut-off values was 61.5% (specificity 92.0%) for the mouth-breathing group, and 77.5% (specificity 56.3%) for the suspected mouth-breathing group.Information was also obtained from visual assessment of maxillofacial characteristics. We found that the mouth-breathing and suspected mouth-breathing groups showed significantly high odds ratios for 7 items: discomfort while breathing and increased chin muscle tonus with lip closure, maxillary protrusion, tongue thrust, open mouth at rest, open bite, and childhood asthma. For 94.6% of the nose breathing group, ≥1 of these items applied.

Conclusions

These findings were then used together to create a sample screening form. We believe that screening of this kind can facilitate more accurate diagnosis of habitual mouth breathing and contribute to its early detection.

     

Effect of nasal decongestion on nasalance measures.

OBJECTIVE: The purpose of this study was to evaluate the effect of nasal decongestant on nasalance scores for a group of 100 individuals. PARTICIPANTS: Forty-one subjects with hypernasality and 59 subjects without hypernasality underwent nasometric assessment at the Hospital for Rehabilitation of Craniofacial Anomalies, University of S?o Paulo, Bauru, Brazil. DESIGN: Nasalance scores were obtained for each subject before the application of a nasal decongestant and again 10 minutes after subjects received a topical nasal decongestant applied into both nostrils. RESULTS: The nasalance scores obtained after the application of the nasal decongestant were significantly higher than those obtained before the decongestant. CONCLUSIONS: Nasal decongestion had a small but statistically significant effect on nasalance scores, suggesting that in some individuals, nasal congestion should be a variable of concern when using the Nasometer. Both nasal congestion (i.e., due to nasal rhinitis) and the effects of nasal decongestant sprays may influence Nasometer test results. Interpretation of nasalance scores, therefore, should be done carefully. Furthermore, nasometry, with and without nasal decongestant, can be a valuable clinical tool for screening anterior nasal obstruction, helping to isolate obstruction due to nasal congestion from structural obstruction in the nasal cavities.     

间歇性鼻阻塞对幼年大鼠髁突软骨细胞成软骨作用的早期影响

目的: 建立幼年大鼠双侧间歇性鼻阻塞动物模型,探讨鼻阻塞对髁突软骨细胞（mandibular condylar chondrocytes,MCCs）成软骨作用的早期影响。 方法: 64只4周龄SD大鼠随机分为4组,每组16只。A组：对照组,不做处理;B组：间歇性鼻阻塞引起开口呼吸4 d后,去除鼻阻塞因素;C组：间歇性鼻阻塞引起开口呼吸8 d后,去除鼻阻塞因素;D组：间歇性鼻阻塞引起开口呼吸16 d。鼻阻塞时间为每天8：00-16：00。在建模第4、8、12、16天,分别取4组大鼠双侧髁突,进行MCCs体外培养并鉴定,RT-PCR法检测4组MCCs成软骨标志基因（SOX9、COL2a、ACAN、PTHrp）表达的差异。采用 SPSS19.0软件包对实验数据进行统计学分析。 结果: 与对照组相比,4 d时B组、C组和D组SOX9、COL2a以及ACAN表达量均显著下降（P<0.05）,但PTHrp表达量显著升高（P<0.05）。8 d时,B组、C组和D组SOX9、COL2a、ACAN、PTHrp表达量均升高,且B组较C组和D组升高更显著（P<0.05）。12 d时,B、C和D组PTHrp的表达仍显著升高（P<0.05）,COL2a、ACAN的表达与对照组持平或降低。16 d时,C组COL2a、ACAN、PTHrp表达量较对照组显著升高（P<0.05）,B组和D组各项基因表达与对照组持平或降低。 结论: 幼年大鼠在早期双侧间歇性鼻阻塞致开口呼吸的情况下,髁突软骨细胞成软骨能力呈现先下降,随后代偿性升高,最终仍表现为下降的趋势。早期去除鼻阻塞因素后,髁突软骨细胞成软骨能力可以短期代偿性增强,但长期作用仍然是成软骨能力降低。     

Orthodontist-otorhinolaryngologist: an interdisciplinary approach to solve otitis media.

AIM: This was to investigate in oral breathing children with an associated atypical pattern of swallowing and otitis media, the effects of rapid maxillary expansion on nasal airway resistance and conductive hearing loss. MATERIALS AND METHODS: This study examined 24 children (16 males and 8 females) in early mixed dentition period, with an age range of 6-8 years (mean age 7 years), diagnosed with otitis media from the otorhinolaryngology Department of "Tor Vergata" Hospital. The young patients were seen in the Department of Orthodontics, Faculty of Dentistry University of Rome "Tor Vergata". All the subjects had an open mouth breathing pattern with a secondary atypical swallowing mode and a conductive hearing loss resulting from otitis media. The therapeutic approach was to apply a RPE fixed appliance (Butterfly expander). RESULTS: Follow up showed that after rapid maxillary expansion there was nasal resistance reduction, increased nasal airflow and improvement in conductive hearing loss. CONCLUSION Rapid maxillary expansion has been used for both dental and rhinological purposes in the belief that clinically significant reductions in nasal resistance to airflow and an improvement in conductive hearing loss occur predictably.     

Nasal airway impairment: the oral response in cleft palate patients

The purpose of this study was to assess the oral response to severe nasal airway impairment in patients with cleft palate. Inductive plethysmography was used to measure the percent of nasal breathing, and the pressure-flow technique was used to estimate nasal area in 15 persons with severe nasal airway impairment. Mean nasal area was 0.17 cm2, and the average percent of nasal breathing was 20%. Analysis revealed a strong correlation (0.87) between nasal size and percent of nasal breathing in this selected group. Modeling studies based on the mean values from the subjects' data indicated that the model "mouth" would have to open 0.5 cm2 to shunt 80% of the airflow orally, an amount equivalent to the mean value of the subjects' respiratory mode. More important, the extrapolated data revealed that upper-airway resistance decreased in the model from 8.7 cm H2O/L/sec to a level of 3.2 cm H2O/L/sec, which is an average value for healthy adults. These data support the concept that the mouth acts as a variable resistor to maintain an optimal respiratory tract resistance when the nasal airway is impaired.     

Influence of habitual mouth breathing on taste sensation

Purpose

Although habitual mouth breathing is recognized to cause various disorders of orofacial growth and function, including taste sensation, the relationship between habitual mouth breathing and taste disorders has not been investigated sufficiently. This study aimed to examine the influence of habitual mouth breathing on taste sensitivity and relevant factors such as salivation, oral moisture, and olfactory function.

The effects of chronic absence of active nasal respiration on the growth of the skull: A pilot study

Oral respiration associated with an obstructed nasal airway is common in orthodontic patients. For several years chronic oral respiration has been implicated as a prime causative factor in the development of "adenoid facies or the "long-face syndrome. The animal experiment reported here begins a series designed to study, as separate variables, the 2 components of chronic oral respiration: (1) chronic absence of active nasal respiration and 2) chronic mouth opening to find out what dentofacial changes can be attributed to chronic absence of active nasal respiration alone. In this pilot study, 5 growing dogs underwent tracheotomy so that significant active nasal respiration was not possible and oral respiration was not essential.     

Effects of short term forced oral breathing: physiological changes and structural adaptation of diaphragm and orofacial muscles in rats

Objective

We studied adaptation of diaphragm and orofacial muscles as well as hormonal responses to forced oral breathing (lasting for only 4 days) following reversible bilateral nasal obstruction performed on day 8 post-natal male rats.

Design

Muscle myosin heavy chain (MHC) composition and hormone levels were analysed during two periods: 1 and 3 days after obstruction (days 9 and 11 post-natal), and following 3 months recovery with nasal breathing (90 days, adult).

Results

Diaphragm muscle showed significant increases in adult isoforms (MHC 1, 2a) in oral breathing group versus control. We observed increases in MHC neonatal and adult type 1 isoforms in muscles involved with oral breathing, masseter superficialis and anterior digastric. No changes were observed in the levator nasolabialis muscle involved with nasal breathing. Reversible nasal obstruction was associated with reduced growth of the olfactory bulbs lasting into adulthood, and an initial decrease in lung growth followed by recovery at 90 days. Adrenal hypertrophy was observed after 1 day of nasal obstruction and lasted into adulthood. The “stress” hormone response was variable, increased (over 1000%) during the obstruction but normal by adulthood. An increase in plasma testosterone was observed during the obstruction, and a decrease in thyroid hormone levels throughout.

Conclusions

Very short term nasal obstruction, i.e. forced oral breathing, leads to long term hormonal changes and respiratory muscle fibre adaptation.     

Relationship between mandibular incisor crowding and nasal mucosal swelling.

In this study, cephalometric and dental cast variables relating to 30 male and 20 female children, 8 to 13 years old with chronic nasal mucosal swelling, were compared with those relating to age- and sex-method controls. These controls were orthodontically untreated subjects with no histories of airway obstruction. The children with chronic nasal mucosal swelling had been referred because of chronic difficulties with nasal breathing to the Department of Otolaryngology Airflow Laboratory at the Hospital for Sick Children in Toronto. Previously active posterior rhinomanometry with a head-out volume displacement plethysmograph had been used to measure nasal resistance in 1000 consecutive subjects. Participants in the study reported here were selected from subjects whose nasal resistance fell markedly following administration of a decongestant spray. The subjects selected were found to have significantly (p less than 0.001) more mandibular incisor crowding, significantly (p less than 0.01) smaller mandibular arch widths than the controls, and significantly (p less than 0.001) smaller maxillary arch widths than the controls. The male subjects had significantly (p less than 0.01) smaller mandibular arch widths than the male controls.     

Influence of myofunctional therapy on the perioral muscles. Clinical and electromyographic evaluations

The purpose of this study was to evaluate the influence of oral myofunctional therapy on the superior and inferior orbicularis oris (OOS and OOI) and mentalis (MT) muscles at rest and with lips closed in mouth breathing patients with no nasal airway obstruction. The sample consisted of 13 children aged 5-10 years. Clinical and electromyographic evaluations were performed before and after treatment. The results showed that muscles (P < 0.05) and functions (P < 0.01) improved after therapy, which can be observed by clinical evaluations. The electrical activity increase between rest and closed lip positions was statistically significant for the muscles studied. Before therapy the significant minimal level (s.m.l.) was P < 0.01 and after therapy it was P < 0.05. When the difference between the rest and closed lip positions before and after therapy was compared, a statistically significant decrease (P < 0.05) in the electrical activity of the OOI and MT muscles was observed. There was no correlation between the root-mean-square (RMS) of the OOI and MT muscles with the morphological and functional evaluations. The therapy can improve morphology and function of the muscles in mouth breathing patients with no nasal airway obstruction.     

Electromyographic muscle EMG activity in mouth and nasal breathing children

Mouth breathing may cause changes in muscle activity, because an upper airway obstruction leads may cause a person to extend his/her head forward, demanding a higher inspiratory effort on the accessory muscles (sternocleidomastoids). This purpose of this study is to compare, using electromyography (EMG), the activity pattern the sternocleidomastoid and upper trapezius muscles in mouth breathing children and nasal breathing children. Forty-six children, ages 8-12 years, 33 male and 13 female were included. The selected children were divided into two groups: Group I consisted of 26 mouth breathing children, and Group II, 20 nasal breathing children. EMG recordings were made using surface electrodes bilaterally in the areas of the sternocleidomastoideus and upper trapezius muscles, while relaxed and during maximal voluntary contraction. The data were analyzed using the Kruskall-Wallis statistical test. The results indicated higher activity during relaxation and lower activity during maximal voluntary contraction in mouth breathers when compared to the nasal breathers. It is suggested that the activity pattern of the sternocleidomastoid and upper trapezius muscles differs between mouth breathing children and nasal breathing children. This may be attributed to changes in body posture which causes muscular imbalance. Because of the limitations of surface EMG, the results need to be confirmed by adding force measurements and repeating the experiments with matched subjects.     

Rapid maxillary expansion and surgically assisted rapid maxillary expansion effects on nasal volume

The purpose of this study was to compare the effects of rapid maxillary expansion (RME) and surgically assisted rapid maxillary expansion (SARME) on nasal volume using acoustic rhinometric methods. Two groups of subjects were used in the study. Group 1 consisted of 10 subjects (mean age 12.30 +/- 0.82 years) who were treated with RME, and group 2 consisted of 10 subjects (mean age 18.70 +/- 2.54 years) who were treated by SARME. In both groups, all cases had a maxillary width deficiency with bilateral crossbites. Nasal volume records were taken by the same otorhinolaryngologist with an AR device. AR recordings were performed for each patient with and without the use of a decongestant. The first record was taken before expansion, and the second record was taken at the end of retention. The data for both groups were evaluated using Wilcoxon signed rank test and Mann-Whitney U-test. The nasal volume showed a significant increase in both the RME and the SARME groups (P < .05). The measurement with the use of decongestant was similar to that without use of decongestant on the both groups (P < .05), but the different increments in nasal volume between the RME and the SARME groups were not statistically significant. Although the mean ages between the RME and the SARME groups were different, the increase in nasal volume was similar in both groups.     

Endoscopic partial adenoidectomy for children with submucous cleft palate.

OBJECTIVE: Children with submucous cleft palate who suffer from chronic nasal obstruction because of hypertrophic adenoids usually are not subjected to adenoidectomy because of the fear of postoperative velopharyngeal insufficiency. These patients present a therapeutic challenge because we are aware more than ever of the importance of normal nasal breathing and nocturnal respiration, especially during childhood. Our hypothesis was that transnasal endoscopic horizontal limited adenoidectomy may relieve nasal obstruction while preserving the function of the velopharyngeal valve. The objective of this study was to evaluate the efficacy of transnasal endoscopic horizontal partial adenoidectomy in patients with submucous cleft palate and adenoidal hypertrophy. SETTING: Patients were either referred to the outpatient clinic of the Palate Surgery Unit (seven patients) or were patients referred to the senior author's (Y.F.) private clinic. All the patients had been operated on by this senior author (Y.F.). PATIENTS: Ten children aged 3.5 to 13 years (six girls and four boys) with submucous cleft palate and hypertrophic adenoids were included in the study. All the patients were hyponasal and suffered nasal obstruction, loud snoring, and episodes of apnea. INTERVENTIONS: Endoscopic partial adenoidectomy was accomplished to open the lower third of the choanae. Nasal breathing was achieved in all the patients, and only mild snoring remained in two patients. The hyponasality disappeared and speech intelligibility normalized. Mild hypernasality developed in two patients but was still perceived as an overall improvement in speech. CONCLUSIONS: Transnasal endoscopic horizontal partial adenoidectomy may be an effective surgical method for relief of nasal obstruction while preserving velopharyngeal valve function in patients with submucous cleft palate who suffer from obstructive adenoids.