Nose vs. mouth breathing- acute effect of different breathing regimens on muscular endurance.

BACKGROUND: It has been reported that the way we breathe (whether through the nose or mouth) can influence many aspects of our health and to some extent, sport performance. The purpose of this study was to evaluate the acute effects of different breathing regimens on muscular endurance and physiological variables. METHODS: A randomized experiment to verify the acute effect of different breathing regimens (NN- inhaling and exhaling through the nose; NM- inhaling through the nose, exhaling through the mouth; MM- inhaling and exhaling through the mouth) on the muscular endurance performance was conducted. 107 physically active college students (68 males, 39 females) performed repeated bench press testing protocol (repetitions to failure (RTF) with 60% of body weight for males (BP60), respectively 40% of body weight for females (BP40)) with various breathing regimens (NN, NM, MM) in random order. Heart rate (HR), blood oxygen saturation (SpO2) and perceived exertion by Borg scale (RPE) were measured as well. A short questionnaire, given after the testing protocol and observation during familiarization, was used to detect each subject's normal breathing approach during resistance training. RESULTS: In both genders, no significant differences in RTF, RPE and SpO2 were found. No individual case of deviation of arterial oxygen saturation outside the physiological norm was recorded. ​​In the male group, significantly lower HR values were found during the NN trials, compared to during the NM (p = 0.033) and MM (p = 0.047) trials with no significant differences in females. The HR differences in the males demonstrated a small effect size (NN < NM, d = 0.32; NN < MM, d = 0.30). Questionnaire results suggest that 80% of our participants use NM breathing, 15% use MM breathing and 5% use NN breathing during resistance training. CONCLUSION: It seems, that various breathing regimens have none or only minor effect on muscular endurance performance and selected physiological parameters. NN seems to be as efficient as other two regimens, which are mostly used in practice (NM, MM).

Mouth Breathing and Its Impact on Atypical Swallowing: A Systematic Review and Meta-Analysis.

The aim of this systematic review is the assessment of the effect of mouth breathing on the prevalence of tongue thrust. The review was performed according to the PRISMA 2020 checklist guidelines, and the protocol was registered with PROSPERO (CRD42022339527). The inclusion criteria were the following: studies of clinical trials and cross-sectional and longitudinal descriptive studies that evaluate the appearance of tongue thrust in patients with mouth breathing; healthy subjects of any age, race or sex; and studies with a minimum sample group of five cases. The exclusion criteria were the following: studies with syndromic patients, articles from case reports, and letters to the editor and/or publisher. Searches were performed in electronic databases such as The National Library of Medicine (MEDLINE via PUBMED), the Cochrane Central Register of Controlled Trials, Web of Science and Scopus, including studies published until November 2023, without a language filter. The methodological quality of the included case-control studies was assessed using the Newcastle-Ottawa Scale (NOS), and the Joanna Briggs Institute (JBI) tool was used for descriptive cross-sectional studies and cross-sectional prevalence studies. A meta-analysis was conducted on studies that provided data on patients' classification according to mouth breathing (yes/no) as well as atypical swallowing (yes/no) using Review Manager 5.4. From 424 records, 12 articles were selected, and 4 were eligible for meta-analysis. It was shown that there is no consensus on the diagnostic methods used for mouth breathing and tongue thrust. The pooled risk ratio of atypical swallowing was significantly higher in the patients with mouth breathing (RR: 3.70; 95% CI: 2.06 to 6.66). These studies have several limitations, such as the heterogeneity among the individual studies in relation to the diagnostic tools and criteria for the assessment of mouth breathing and atypical swallowing. Considering the results, this systematic review shows that patients with mouth breathing presented higher risk ratios for atypical swallowing.

Quantitative microbial risk assessment with nasal/oral breathing pattern for S. aureus bioaerosol emission from aeration tanks and residual sludge storage yard in a wastewater treatment plant.

A large number of pathogenic bioaerosols are generated during the treatment process of wastewater treatment plants (WWTPs), and they can pose potential risks to human health. Therefore, this study systematically analyzed the emission characteristics of Staphylococcus aureus bioaerosols released from an inverted umbrella aeration tank, a microporous aeration tank, and a residual sludge storage yard in a WWTP, and quantitatively evaluated the health risks of four kinds of exposed populations with nasal/oral breathing patterns under optimistic and conservative estimations. The results displayed that the bioaerosol concentration in inverted umbrella aeration tank was higher than that in microporous aeration tank and residual sludge storage yard. Aerosolization ratio in residual sludge storage yard was an order of magnitude lower than that in aeration tanks. Sludge workers were at higher health risks than the other three exposed populations. The health risks of nasal breathers (infection risk: 1.62 × 10-5-2.56 × 10-3 pppy; disease burden: 4.24 × 10-8-6.72 × 10-6 DALYs pppy) were 0.61-0.63 times higher than those of oral breathers (infection risk: 9.95 × 10-6-1.59 × 10-3 pppy; disease burden: 2.61 × 10-8-4.18 × 10-6 DALYs pppy). For female field engineers using oral breathing, laboratory technicians, and researchers without personal protective equipment (PPE), infection risk and disease burden had the opposite results, which indicated that satisfying one certain benchmark did not mean absolute safety. In addition, health risks of exposed populations were reduced by an order of magnitude after wearing PPE. This study can provide a reliable theoretical basis for the risk prevention of bioaerosols and supply data support for the strategies of health risk control perspectives for local sewage utilities.

Paper-Based Humidity Sensor for Respiratory Monitoring.

Flexible respiratory monitoring devices have become available for outside-hospital application scenarios attributable to their improved system wearability. However, the complex fabrication process of such flexible devices results in high prices, limiting their applications in real-life scenarios. This study proposes a flexible, low-cost, and easy-processing paper-based humidity sensor for sleep respiratory monitoring. A paper humidity sensing model was established and sensors under different design parameters were processed and tested, achieving high sensitivity of 5.45 kΩ/%RH and good repeatability with a matching rate of over 85.7%. Furthermore, the sensor patch with a dual-channel 3D structure was designed to distinguish between oral and nasal breathing from origin signals proved in the simulated breathing signal monitoring test. The sensor patch was applied in the sleep respiratory monitoring of a healthy volunteer and an obstruct sleep apnea patient, demonstrating its ability to distinguish between different respiratory patterns as well as various breathing modes.

Rapid Maxillary Expansion (RME): An Otolaryngologic Perspective.

Background. To evaluate the possible effects of Rapid Maxillary Expansion (RME), such as nasal breathing problems, middle ear function, Obstructive Sleep Apnea (OSA) in the otolaryngology field. RME has already been introduced in orthodontics to expand the maxilla of young patients affected by transversal maxillary constriction. Methods. A literature search was performed using different databases (Medline/PubMed, EMBASE, and CINAHL), from May 2005 to November 2021, according to the PRISMA guidelines. Results. The application of RME in children has shown good results on nasal function, reducing nasal resistances, independently from a previous adenotonsillectomy. These results are not only related to the increasing of nasal transverse diameters and volume, but also to the stiffening of airway muscles, enabling the nasal filtrum function and avoiding mouth opening, thereby decreasing respiratory infections. Positive effects have also been reported for the treatment of conductive hearing loss and of OSA, with the reduction of Apnea Hypopnea Index (AHI), possibly due to (i) an increased pharyngeal dimensions, (ii) a new tongue posture, and (iii) reduced nasal respiratory problems. Conclusions. Otolaryngologists should be aware of the indications and benefits of the RME treatment, considering its possible multiple beneficial effects.

Obstructive sleep apnea -consideration of its pathogenesis.

The pathogenesis of obstructive sleep apnea (OSA) is characterized not only by obstruction of the pharynx, but also by repeated obstruction. OSA onset is thought to involve four phenotypic traits: pharyngeal muscle responsiveness, respiratory center instability (loop gain), arousal threshold, and anatomical factors. Patients with lower muscle responsiveness are likely to have OSA, whereas those with higher responsiveness are not. When the loop gain is relatively high, reaction and suppression of the respiratory drive are repeated, decreasing ventilation and pharyngeal muscle activity and leading to mixed or central apnea events. Patients with a low arousal threshold tend to have frequent respiratory events and less severe respiratory efforts, whereas those with a high arousal threshold tend to have fewer respiratory events and more severe respiratory efforts. Pharyngeal muscle activity, as well as respiratory drive, increases during apnea and decreases after its release. Patients with a low arousal threshold have lower muscle responsiveness and instability of the respiratory center control, whereas those with a high arousal threshold have higher muscle responsiveness and relatively stable respiratory control. The overshoot and undershoot responses of the chemical drive and pharyngeal muscle tone characterize the periodic repetition of obstructive events, which are enhanced by the arousal response. The presence of certain anatomical factors is prerequisite for the onset of OSA. Also, not only volume and flow, but also stiffness and elasticity may contribute to the pathogenesis of OSA. Mouth breathing also plays an important role in the mechanism of pharyngeal collapse. These four factors influence each other, with the first three-muscle responsiveness, loop gain, and arousal threshold-in particular in a trinity. The era is already close in which not only anatomical treatment, but also treatments for other traits can be selected and combined according to the individual pathophysiological condition of each patient with OSA.

Investigation on the Effect of Oral Breathing on Cognitive Activity Using Functional Brain Imaging.

Oral breathing directly affects behavioral performance and dental health. Various relationships between oral breathing and periodontal disease have been well-described. However, the effect of oral breathing on cognitive performance remains unclear. This study aimed to investigate the effects of oral breathing on cognitive function using functional magnetic resonance imaging (fMRI). Twenty-two healthy participants (mean age, 22.27 ± 1.42 years) performed a two-back (2B) working memory fMRI task using a 3T MRI scanner while breathing through their oral or nasal passage. Functional activity analysis was performed using a statistical parametric mapping software package. One-sample group analyses were performed in 2B > Rest contrast. Functional connectivity analysis was conducted using MATLAB-based imaging software. Mixed ANOVA analysis was performed. The results showed more brain activation and connection during nasal breathing than during oral breathing. For Nasal > Oral contrast, various functional connections are known to have a significant relationship with working memory, including the left cerebellum, left and right inferior parietal gyrus. This can be significant evidence to demonstrate that oral breathing is an inappropriate method for intellectual activity using brain imaging techniques. Therefore, this study suggests that changing various habits related to oral breathing is important for cognitive function.

Weblog "How Do I Breathe?"-Design and View Statistics

Abstract Introduction Breathing is one of the vital functions of the body and is essential for the maintenance of life. Preventive measures for respiratory disorders can be used by the population, as well as early self-diagnosis and immediate search for treatment based on knowledge of this subject. Objective this study developed a weblog on the breathing function targeting young people and analyzed the statistical data of views until the present moment. Methods The weblog was developed, and the stages of analysis, design, development and implementation were followed. All texts were evaluated by the Flesch Reading Index to verify the language, and the statistical data were analyzed by the number of views, countries with the highest number of views, search terms used, most viewed pages and number of comments on the blog. Results Issues related to the breathing function and thosemost cited in the literature were selected. The blog was structured using pages with content and curiosities, with texts with minimum readability of 50%, and was made available on the internet by means of the Wordpress tool. The statistics showed an increase in the number of visits after August 2015; the countries with the highest number of views were Brazil, United States and Portugal; the search terms used were unknown or related to mouth breathing; the most viewed pages related to mouth breathing and the comments addressed questions on mouth breathing, reports and compliments. Conclusion The blog "How do I breathe?," aimed at young people and containing information about the breathing function, was developed and is available on the internet at the address: https://comoeurespiro.wordpress.com. (AU)

Weblog "How Do I Breathe?"-Design and View Statistics.

Introduction Breathing is one of the vital functions of the body and is essential for the maintenance of life. Preventive measures for respiratory disorders can be used by the population, as well as early self-diagnosis and immediate search for treatment based on knowledge of this subject. Objective this study developed a weblog on the breathing function targeting young people and analyzed the statistical data of views until the present moment. Methods The weblog was developed, and the stages of analysis, design, development and implementation were followed. All texts were evaluated by the Flesch Reading Index to verify the language, and the statistical data were analyzed by the number of views, countries with the highest number of views, search terms used, most viewed pages and number of comments on the blog. Results Issues related to the breathing function and those most cited in the literature were selected. The blog was structured using pages with content and curiosities, with texts with minimum readability of 50%, and was made available on the internet by means of the Wordpress tool. The statistics showed an increase in the number of visits after August 2015; the countries with the highest number of views were Brazil, United States and Portugal; the search terms used were unknown or related to mouth breathing; the most viewed pages related to mouth breathing and the comments addressed questions on mouth breathing, reports and compliments. Conclusion The blog "How do I breathe?," aimed at young people and containing information about the breathing function, was developed and is available on the internet at the address: https://comoeurespiro.wordpress.com .

Quantitative evaluation of tongue pressure in children with oral breathing / Avaliação quantitativa da pressão de língua em crianças com respiração oral

ABSTRACT Objective: to quantify tongue pressure in children with oral breathing and to describe their respiratory clinical manifestations, comparing them to the objective evaluation Methods: the study was performed with 60 children, four to nine years old, treated at the outpatient clinics of the Pernambuco Clinical Hospital, Federal University of Pernambuco, distributed into two groups, with and without oral breathing. The collection consisted of a survey of respiratory clinical manifestations, application of the protocol on respiratory mode and assessment of tongue pressure, using the Iowa Oral Performance Instrument (IOPI). Results: male predominance and correlation between diagnosis of allergic rhinitis and/or nasal obstruction and the clinical diagnosis of oral breathing were observed. There was a statistically significant difference between the groups for usual position of open lips, open mouth, sagging facial expression muscles, narrow nostrils, shortened upper and everted lower lip. The mean tongue pressure in children with oral and nasal breathing presented a mean of 38.27 Kpa and 53.73 Kpa, respectively. Conclusion: tongue pressure decreased in children with oral breathing, corroborating that which is reported in the literature. There was agreement between the results of respiratory clinical characteristics and the objective evaluation.

RESUMO Objetivo: quantificar a pressão de língua em crianças com respiração oral e descrever as suas manifestações clínicas respiratórias, comparando-as à avaliação objetiva. Métodos: o estudo foi realizado com 60 crianças de 04 a 09 anos de idades atendidas nos ambulatórios do Hospital das Clínicas da Universidade Federal de Pernambuco, distribuídas em dois grupos, com e sem respiração oral. A coleta constou do levantamento das manifestações clínicas respiratórias, da aplicação do protocolo sobre o modo respiratório e da avaliação da pressão de língua utilizando o Iowa Oral Performance Instrument (IOPI). Resultados: observou-se predominância do sexo masculino e correlação entre o diagnóstico clínico de rinite alérgica e/ou obstrução nasal com o diagnóstico clínico de Respiração oral. Houve diferença estatisticamente significante entre os grupos para posição habitual dos lábios entreabertos, boca aberta, flacidez dos músculos da expressão facial, narinas estreitas, lábio superior encurtado e inferior evertido. As médias das pressões de língua em crianças com respiração oral e nasal apresentaram médias de 38,27 Kpa e 53,73 Kpa, respectivamente. Conclusão: foi verificada diminuição da pressão de língua em crianças com respiração oral, corroborando com o que é referido na literatura. Houve concordância entre os resultados das características clínicas respiratórias com a avaliação objetiva.

Association of breathing patterns and quality of life in patients with nasal obstruction.

INTRODUCTION: In the general population, nasal obstruction is a common complaint. However, an objective evaluation of nasal obstruction is difficult. Nose examination, computed tomography (CT), acoustic rhinometry, and anterior rhinomanometry do not accurately reflect the discomfort reported by patients with nasal obstruction. In patients with nasal obstruction, this study evaluated nasal breathing with a unique device for continuous nasal-oral spirometry - a nasal-oral flow analyzer (NOFA); moreover, quality of life was compared between patients with normal nasal breathing on NOFA and of those with impaired nasal breathing on NOFA. METHODS: Of 181 adult patients admitted to an ENT department due to nasal obstruction that were enrolled in the study, 97 (53.6%) completed all per-protocol assessments, including the SF-36 questionnaire and 3-hour, continuous nasal-oral spirometry with NOFA. Based on the presence of normal nasal breathing defined as ≥95% of nasal flow, the 97 patients were divided into those with normal nasal breathing (n=31) and impaired nasal breathing (n=66). RESULTS: Patients with normal nasal breathing differed from those with impaired nasal breathing with respect to all SF-36 subscales (physical functioning, p=0.004; role-physical, p=0.009; bodily pain, p<0.001; general health, p=0.007; vitality, p=0.002; social functioning, p=0.008; mental health, p=0.009; physical component summary, p<0.001; mental component summary, p=0.02), except for the role-emotional subscale (p=0.1). CONCLUSIONS: Among patients with symptoms of nasal obstruction, compared to patients with normal nasal breathing, those with impaired nasal breathing had significantly lower quality of life in the physical and mental domains. Further research needs to determine whether NOFA can be used to diagnose nasal obstruction.

Postural disorders in mouth breathing children: a systematic review.

BACKGROUND: Mouth breathing syndrome can cause sleep disturbances that compromise the performance of children in school. It might also cause postural abnormalities involving the head and cervical spine; however, the association between postural abnormalities and mouth breathing in children is unclear. OBJECTIVE: To assess the methodological quality of studies and determine if there is an association between mouth breathing and postural disorders in children. METHODS: Databases comprised MEDLINE, CINAHL, PEDro, LILACS, EMBASE and Cochrane Central Registrar of Controlled Trials. Searches were until March 2016 and included studies that evaluated postural disorders in children diagnosed with mouth breathing. The Downs and Black checklist was used to evaluate the quality of the evidences. RESULTS: Ten studies were included totaling 417 children from 5 to 14 years. Two studies used the New York State Postural Rating Scale, seven used photography and one used motion capture to measure posture. The methods used to analyze the data included the Postural Analysis Software (SAPO), Fisiometer, ALCimagem and routines in MATLAB program. Quality assessment resulted in low scores (<14) for all the studies. The main areas of weakness were a clear description of the participants, of the methods used to access posture, of the principal confounders and lack of power analysis. External and internal validity were also threatened by the lack of a representative sample and blinding of the participants and assessors, respectively. CONCLUSIONS: The review provides low evidence that mouth-breathing pattern in children between the ages 5-14 years is associated with postural deviations.

Unilateral nasal obstruction induces degeneration of fungiform and circumvallate papillae in rats.

BACKGROUND: In clinical orthodontic treatment, chronic respiratory disturbance or mouth breathing has been concerned symptoms and screening criteria. In this study, to analyze the relation between nasal obstruction and taste sensing, a unilateral nasal obstruction model was performed to investigate the taste papillae and taste buds in rats. METHODS: Fourteen 6-day-old male Wistar rats were randomly divided into control and experimental groups (n = 7 each). The experimental group underwent unilateral nasal obstruction at 8 days of age. The rats were euthanized at 9-week-old. The morphology of the circumvallate papillae and taste buds were identified by immunohistochemical methods. The fungiform papillae were visualized with 1% methylene blue and sectioned for taste bud observation. RESULTS: Some defects in the gustatory epithelium were observed after unilateral nasal obstruction. Rats in the experimental group had significantly fewer fungiform papillae and smaller volumes of taste bud. In circumvallate papillae, smaller total taste bud area was found in experiment group. CONCLUSION: Findings in the present study suggest that nasal obstruction might have significant influences on the gustatory function via morphologic change in the taste papillae and taste buds in tongue area.

Frequency of rhinitis and orofacial disorders in patients with dental malocclusion / Frequência de rinite e alterações orofaciais em pacientes com má oclusão dentária

Objective: To describe the frequency and etiology of rhinitis, oral breathing, types of malocclusion and orofacial disorders in patients treated for dental malocclusion. Methods: Patients with poor dental occlusion (n=89, 8-15 years) undergoing orthodontic treatment at the Postgraduate Orthodontics Center (São Paulo, Brazil) participated in the study. Rhinitis and oral breathing were diagnosed by anamnesis, clinical assessment and allergic etiology of rhinitis through immediate hypersensitivity skin prick test with airborne allergens. The association between types of breathing (oral or nasal), rhinitis and types of dental malocclusion, bruxism and cephalometric alterations (increased Y axis of facial growth) compared to standard cephalometric tracing (Escola de Odontologia da Universidade de São Paulo) were assessed. Results: The frequency of rhinitis in patients with dental malocclusion was 76.4% (68), and, of these, 81.7% were allergic (49/60 positive skin prick test), whereas the frequency of oral breathing was 62.9%. There was a significant association between an increased Y axis of facial growth and oral breathing (p<0.001), as well as between oral breathing and rhinitis (p=0.009). There was no association between rhinitis and bruxism. Conclusions: The frequency of rhinitis in children with dental malocclusion is higher than that in the general population, which is approximately 30%. Patients with oral breathing have a tendency to a dolichofacial growth pattern (increased Y axis of facial growth). In patients with rhinitis, regardless of the presence of oral breathing, the dolichofacial growth tendency was not observed.

Objetivo: Descrever a frequência e etiologia da rinite, da respiração oral, os tipos de má oclusão e as alterações orofaciais em pacientes tratados por má oclusão dentária. Métodos: Pacientes com má oclusão dentária (n=89, oito a 15 anos) em tratamento ortodôntico em centro de pós-graduação em ortodontia (São Paulo, Brasil) participaram do estudo. Rinite e respiração oral foram diagnosticadas por anamnese e exame clínico e a etiologia alérgica dessa por teste cutâneo de hipersensibilidade imediata (TCHI) com aeroalérgenos. Avaliou-se a relação entre tipos de respiração (oral ou nasal), rinite e tipos de má oclusão dentária, bruxismo e alterações cefalométricas (aumento do eixo Y de crescimento facial) em comparação com o traçado cefalométrico padrão (Escola de Odontologia da Universidade de São Paulo). Resultados: A frequência de rinite nos pacientes com má oclusão dentária foi de 76,4% (68), desses 81,7% eram alérgicos (49/60 TCHI positivo) e a frequência de respiração oral foi de 62,9%. Houve associação significativa entre ter o eixo Y de crescimento facial aumentado e respiração oral (p<0,001), o mesmo entre respiração oral e rinite (p=0,009). Não houve associação entre rinite e bruxismo. Conclusões: A frequência de rinite em crianças com má oclusão dentária é superior à da população geral, que gira ao redor de 30%. Os pacientes com respiração oral têm tendência de crescimento dólico facial (eixo Y de crescimento aumentado). Nos pacientes com rinite, independentemente da presença da respiração oral, a tendência dólico facial não foi observada.

[Frequency of rhinitis and orofacial disorders in patients with dental malocclusion]. / Frequência de rinite e alterações orofaciais em pacientes com má oclusão dentária.

OBJECTIVE: To describe the frequency and etiology of rhinitis, oral breathing, types of malocclusion and orofacial disorders in patients treated for dental malocclusion. METHODS: Patients with poor dental occlusion (n=89, 8-15 years) undergoing orthodontic treatment at the Postgraduate Orthodontics Center (Sao Paulo, Brazil) participated in the study. Rhinitis and oral breathing were diagnosed by anamnesis, clinical assessment and allergic etiology of rhinitis through immediate hypersensitivity skin prick test (SPT) with airborne allergens. The association between types of breathing (oral or nasal), rhinitis and types of dental malocclusion, bruxism and cephalometric alterations (increased Y axis of facial growth) compared to standard cephalometric tracing (Escola de Odontologia da Universidade de São Paulo) were assessed. RESULTS: The frequency of rhinitis in patients with dental malocclusion was 76.4% (68), and, of these, 81.7% were allergic (49/60 positive skin prick test), whereas the frequency of oral breathing was 62.9%. There was a significant association between an increased Y axis of facial growth and oral breathing (p<0.001), as well as between oral breathing and rhinitis (p=0.009). There was no association between rhinitis and bruxism. CONCLUSIONS: The frequency of rhinitis in children with dental malocclusion is higher than that in the general population, which is approximately 30%. Patients with oral breathing have a tendency to a dolichofacial growth pattern (increased Y axis of facial growth). In patients with rhinitis, regardless of the presence of oral breathing, the dolichofacial growth tendency was not observed.

Spatiotemporal Quantification of Vocal Fold Vibration After Exposure to Superficial Laryngeal Dehydration: A Preliminary Study.

OBJECTIVES: The aim of the study was to evaluate the effects of a superficial laryngeal dehydration challenge on vocal fold vibration in young healthy adults using high-speed video imaging. SUBJECTS AND METHODS: In this prospective study, the effects of a 60-minute superficial laryngeal dehydration challenge on spatial (speed quotient, amplitude quotient) and temporal measures (jitter percentage, vibratory onset time) of vocal fold vibration and phonation threshold pressure (PTP) were evaluated in 10 (male = 4, female = 6) vocally normal adults (21-29 years). All measures except the vibratory onset time were measured at the 10 (low) and 80 (high) percent level of their pitch range. The vibratory onset time was obtained at habitual pitch and loudness level. Superficial laryngeal dehydration was induced by oral breathing in low ambient humidity. Prechallenge and postchallenge differences were statistically investigated using t tests with Bonferroni correction. RESULTS: The speed quotient at low-pitch phonation significantly decreased after oral breathing of low ambient humidity. Other spatiotemporal measures and PTP at low and high pitch were not significant after challenge. CONCLUSIONS: Results from this initial study have implications for the use of high-speed video imaging to detect and quantify the subtle changes in vocal fold vibrations after superficial dehydration in healthy individuals. Preliminary findings indicate that superficial dehydration in healthy individuals results in spatial deviations at low pitch. However, further studies are warranted to identify additional spatiotemporal changes in vocal fold vibration after superficial dehydration in normal and disordered populations.

Pressure drop of filtering facepiece respirators: How low should we go?

INTRODUCTION: This study was undertaken to determine the mean peak filter resistance to airflow (Rfilter) encountered by subjects while wearing prototype filtering facepiece respirators (PRs) with low Rfilter during nasal and oral breathing at sedentary and low-moderate work rates. MATERIAL AND METHODS: In-line pressure transducer measurements of mean Rfilteracross PRs with nominal Rfilter of 29.4 Pa, 58.8 Pa and 88.2 Pa (measured at 85 l/min constant airflow) were obtained during nasal and oral breathing at sedentary and low-moderate work rates for 10 subjects. RESULTS: The mean Rfilter for the 29.4 PR was significantly lower than the other 2 PRs (p < 0.000), but there were no significant differences in mean Rfilter between the PRs with 58.8 and 88.2 Pa filter resistance (p > 0.05). The mean Rfilter was greater for oral versus nasal breathing and for exercise compared to sedentary activity (p < 0.001). CONCLUSIONS: Mean oral and nasal Rfilter for all 3 PRs was at, or below, the minimal threshold level for detection of inspiratory resistance (the 58.8-74.5 Pa/l×s-1), which may account for the previously-reported lack of significant subjective or physiological differences when wearing PRs with these low Rfilter. Lowering filtering facepiece respirator Rfilter below 88.2 Pa (measured at 85 l/min constant airflow) may not result in additional subjective or physiological benefit to the wearer.

Relationship between Oral Flow Patterns, Nasal Obstruction, and Respiratory Events during Sleep.

STUDY OBJECTIVES: Sleep breathing patterns are altered by nasal obstruction and respiratory events. This study aimed to describe the relationships between specific sleep oral flow (OF) patterns, nasal airway obstruction, and respiratory events. METHODS: Nasal flow and OF were measured simultaneously by polysomnography in 85 adults during sleep. OF was measured 2 cm in front of the lips using a pressure sensor. RESULTS: OF could be classified into three patterns: postrespiratory event OF (postevent OF), during-respiratory event OF (during-event OF), and spontaneous arousal-related OF (SpAr-related OF). Postevent OFs begin at the end of airflow reduction, are preceded by respiratory arousal, and are accompanied by postapneic hyperventilation; during-event OFs occur during nasal flow reduction; and SpAr-related OFs to OF begin during stable breathing, and are preceded by spontaneous arousal but are rarely accompanied by apnea/hypopnea. Multivariate regression showed that nasal obstruction was predictive of SpAr-related OF. The relative frequency of SpAr-related OF events was negatively correlated with the apnea-hypopnea index. The fraction of SpAr-related OF duration relative to total OF duration was significantly greater in patients with nasal obstruction than in those without. CONCLUSION: SpAr-related OF was associated with nasal obstruction, but not respiratory events. This pattern thus functions as a "nasal obstruction bypass", mainly in normal subjects and patients with mild sleep disordered breathing (SDB). By contrast, the other two types were related to respiratory events and were typical patterns seen in patients with moderate and severe SDB.

Impact of short term forced oral breathing induced by nasal occlusion on respiratory function in mice.

Inconsistent findings regarding the experimental nasal obstruction on respiratory functions in small animals have been reported. The purpose of this study was to investigate the impact of short term forced oral breathing on respiratory functions as well as the therapeutic implication of esophageal intubation in BALB/c mice. Thirty BALB/c mice were randomized equally to two groups: an experimental group and control group. Oral breathing was induced by applying petrolatum ointment in nostrils for occlusion both nasal cavities. Esophageal tube was inserted to enlarge the oropharyngeal airway in the experimental mice. Respiratory parameters were measured by barometric whole-body plethysmography (WBP) in the following condition: normal nasal breathing; nasal breathing loading in a soft bag; forced oral breathing loading in a soft bag; forced oral breathing loading in a soft bag after undergoing esophageal intubation. After applying petrolatum ointment of nostrils, all the mice switch to oral breathing with apparent discomfort (bradypnea). Nasal occlusion was associated with a decrease in the average respiratory rate (268±36 vs. 90±10 breaths/min; P<0.01) and an increase in Penh (0.67±0.14 vs. 19.23±2.12; P<0.01). After undergoing esophagus intubation, these mice switched to oral breathing with less discomfort. Compared with the control mice, respiratory rate (175±25 vs. 90±10) was higher; the Penh (8.84±1.05 vs. 18.09±2.03; P<0.01) was lower. Short term forced oral breathing induced by nasal occlusion caused respiratory insufficiency in mice. Stenotic oropharyngeal airway was supposed to be one of the most important factors. Enlarging oropharyngeal airway by esophagus intubation could improve the respiratory insufficiency under nasal occlusion.

Temporary forced oral breathing affects neonates oxygen consumption, carbon dioxide elimination, diaphragm muscles structure and physiological parameters.

OBJECTIVES: We studied adaptation of diaphragm, oxygen consumption and carbon dioxide elimination to forced oral breathing (lasting for only 4 days) following reversible bilateral nasal obstruction performed on day 8 post-natal male rats. METHODS: Diaphragm myosin heavy chain (MHC) composition, oxygen consumption, carbon dioxide elimination and hormones level were analysed during nasal obstruction period. RESULTS: Diaphragm muscle showed significant increases in adult isoforms (MHC 1, 2a) in oral breathing group versus control. Reversible nasal obstruction was associated with a decrease of oxygen consumption and carbon dioxide elimination. Nasal obstruction period was associated with reduced growth of the olfactory bulbs and an initial decrease in lung growth. One day after implementing nasal obstruction, basal corticosterone levels had increased (by over 1000). Oral breathing was also associated with a lower level of thyroid hormone. CONCLUSIONS: We conclude that a 4 day nasal obstruction period in young rats leads to hormonal changes and to Diaphragm myosin heavy chain structural adaptation.