Warming of feet elevates nasal mucosal surface temperature and reduces the early response to nasal challenge with allergen

Nasal air conditioning following total inferior turbinectomy compared to inferior turbinoplasty - A computational fluid dynamics study

BACKGROUND

The aim of this study was to use computational fluid dynamics (CFD) to investigate the effects on nasal heat exchange and humidification of two different surgical techniques for reducing the inferior turbinate under different environmental conditions.

METHODS

Virtual surgery using two techniques of turbinate reduction was performed in eight nasal airway obstruction patients. Bilateral nasal airway models for each patient were compared: 1) Pre-operative 2) Post inferior turbinoplasty 3) Post total inferior turbinate resection (ITR). Two representative healthy models were included. Three different environmental conditions were investigated 1) ambient air 2) cold, dry air 3) hot, humid air. CFD modelling of airflow and conditioning was performed under steady-state, laminar, inspiratory conditions.

FINDINGS

Nasal conditioning is significantly altered following inferior turbinate reduction surgery, particularly with ITR under cold, dry inspired air (CDA). The degree of impairment is minor under the simulated range of environmental conditions (temperature = 12-40 °C; relative humidity = 13-80%). Streams of significantly colder air are found in the nasopharynx and more prevalent under CDA in ITR. These are related to high velocity flow streams, which remain cool in their centre throughout the widened inferior nasal cavity.

INTERPRETATION

Reduced air-mucosal heat exchange and moisture carrying capacity occurs under cooler temperatures in patients following inferior turbinate surgery. The clinical impact in extremely cold and dry conditions in groups with poor baseline respiratory function, respiratory illness, or endurance athletes is of special interest.

Sweat is a most efficient natural moisturizer providing protective immunity at points of allergen entry

Although there is a growing acceptance that sweat could play a detrimental role in various allergic skin diseases, the possibility that sweat is also involved in maintenance of skin hydration and skin-specific immune responses has not been acknowledged. We initially describe physiological role of sweat in both maintaining skin hydration and thermoregulation. The purpose of this article is to provide the reader with objective evidence that sweating is intimately linked to vital stratum corneum barrier function and usefulness of application of moisturizers in clinical care of allergic skin diseases. This review also covers how sweating disturbance would leave the skin vulnerable to the development of various allergic skin diseases, such as atopic dermatitis. New therapeutic approaches would specifically target such sweating disturbance in these allergic skin diseases.

Correlation of Nasal Mucosal Temperature With Subjective Nasal Patency in Healthy Individuals

Importance

Historically, otolaryngologists have focused on nasal resistance to airflow and minimum airspace cross-sectional area as objective measures of nasal obstruction using methods such as rhinomanometry and acoustic rhinometry. However, subjective sensation of nasal patency may be more associated with activation of cold receptors by inspired air than with respiratory effort.

Objective

To investigate whether subjective nasal patency correlates with nasal mucosal temperature in healthy individuals.

Design, Setting, and Participants

Healthy adult volunteers first completed the Nasal Obstruction Symptom Evaluation (NOSE) and a unilateral visual analog scale to quantify subjective nasal patency. A miniaturized thermocouple sensor was then used to record nasal mucosal temperature bilaterally in 2 locations along the nasal septum: at the vestibule and across from the inferior turbinate head.

Main Outcomes and Measures

Nasal mucosal temperature and subjective patency scores in healthy individuals.

Results

The 22 healthy adult volunteers (12 [55%] male; mean [SD] age, 28.3 [7.0] years) had a mean (SD) NOSE score of 5.9 (8.4) (range, 0-30) and unilateral VAS score of 1.2 (1.4) (range, 0-5). The range of temperature oscillations during the breathing cycle, defined as the difference between end-expiratory and end-inspiratory temperatures, was greater during deep breaths (mean [SD] change in temperature, 6.2°C [2.6°C]) than during resting breathing (mean [SD] change in temperature, 4.2°C [2.3°C]) in both locations (P < .001). Mucosal temperature measured at the right vestibule had a statistically significant correlation with both right-side visual analog scale score (Pearson r = -0.55; 95% CI, -0.79 to -0.17; P = .008) and NOSE score (Pearson r = -0.47; 95% CI, -0.74 to -0.06; P = .03). No other statistically significant correlations were found between mucosal temperature and subjective nasal patency scores. Nasal mucosal temperature was lower (mean of 1.5°C lower) in the first cavity to be measured, which was the right cavity in all participants.

Conclusions and Relevance

The greater mucosal temperature oscillations during deep breathing are consistent with the common experience that airflow sensation is enhanced during deep breaths, thus supporting the hypothesis that mucosal cooling plays a central role in nasal airflow sensation. A possible correlation was found between subjective nasal patency scores and nasal mucosal temperature, but our results were inconsistent. The higher temperature in the left cavity suggests that the sensor irritated the nasal mucosa, affecting the correlation between patency scores and mucosal temperature. Future studies should consider noncontact temperature sensors to prevent mucosa irritation.

Level of Evidence

NA.

Impacts of meteorological and environmental factors on allergic rhinitis in children

Meteorological and environmental factors influence the pathogenesis of allergic rhinitis (AR). An understanding of the risk factors will facilitate the development of diagnostic and preventative tools for AR children and improve their quality of life. However, research on the impact of these factors on subjective symptoms in AR children remains scarce. This study explored the relationships between subjective symptoms in pollen and dust mite positive AR children, and meteorological and environmental factors. Using a linear mixed effect model, we analyzed the correlations between monthly data on the subjective symptoms of 351 AR children (from the Shanghai Children's Medical Center) and meteorological and environmental factors during 2013. The monthly meteorological and environmental data were provided by the Shanghai Meteorological Service and Shanghai Environmental Protection Bureau. Temperature and humidity were negatively correlated with the subjective symptom score, with a 0.04 point increase observed for every 1 °C decrease in temperature (P < 0.0001) or 10 % decline in humidity (P = 0.0412). The particulate matter (PM) 10 and PM2.5 concentrations were positively correlated with the subjective symptom score, with a 10 μg/m³ increase in PM10 and PM2.5 yielding a 0.02 (P = 0.0235) and 0.03 (P = 0.0281) increase in the subjective symptom score, respectively. In conclusion, meteorological and environmental factors were correlated with subjective symptoms in AR children. Low temperatures, lower humidity, and high PM10 and PM2.5 concentrations aggravated subjective symptoms in AR children.

Efficacy and Safety of Sublingual Immunotherapy for Allergic Rhinitis in Pediatric Patients: A Meta-Analysis of Randomized Controlled Trials

Background

Allergic rhinitis (AR) has become a global health problem that constantly affects a large part of the general population, especially children.

Objective

Sublingual allergen immunotherapy (SLIT) has been used extensively for pediatric AR, although its efficacy and safety are often questioned. In this meta-analysis of randomized controlled trials (RCT), we evaluated the use of SLIT for pediatric AR.

Methods

A number of medical literature data bases were searched through January 2016 to identify RCTs that examined the use of SLIT for pediatric AR and that assessed clinical outcomes related to efficacy. Descriptive and quantitative information was abstracted. Standardized mean differences (SMD) were calculated by using fixed- and random-effects models. Subgroup analyses were performed. Heterogeneity was assessed by using the I2 metric. A network meta-analysis was used to estimate SMDs between two SLIT protocols for pediatric seasonal AR. All data were extracted from publications or received from the authors.

Results

Twenty-six studies were eligible for inclusion in the meta-analysis of rhinitis or rhinoconjunctivitis symptom scores, and 19 studies were eligible for the meta-analysis of medication scores. Descriptive and quantitative data were extracted. SLIT differed significantly from placebo in terms of symptom scores (SMD -0.55 [95% confidence interval {CI}, -0.86 to -0.25]; p = 0.0003, I2 = 90%) and medication scores (SMD -0.67 [95% CI, -0.96 to -0.38J; p < 0.00001, I2 = 83%). Oral pruritus was the adverse effect, which occurred most commonly in children who were receiving SLIT. Network meta-analysis revealed no significant difference between the pre-coseasonal and continuous SLIT protocols for seasonal AR in symptom scores (SMD -6.55 [95% CI, -25.38 to 12.29]; p = 0.496) and medication scores (SMD -8.83 [95% CI, -22.10 to 4.43]; p = 0.192).

Conclusions

Our meta-analysis results indicated that SLIT provided significant symptom relief and reduced the need for medication in pediatric patients Moreover, the safety of SLIT needs to be confirmed in RCTs with larger samples.

Numerical simulation and nasal air-conditioning

Heating and humidification of the respiratory air are the main functions of the nasal airways in addition to cleansing and olfaction. Optimal nasal air conditioning is mandatory for an ideal pulmonary gas exchange in order to avoid desiccation and adhesion of the alveolar capillary bed. The complex three-dimensional anatomical structure of the nose makes it impossible to perform detailed in vivo studies on intranasal heating and humidification within the entire nasal airways applying various technical set-ups. The main problem of in vivo temperature and humidity measurements is a poor spatial and time resolution. Therefore, in vivo measurements are feasible only to a restricted extent, solely providing single temperature values as the complete nose is not entirely accessible. Therefore, data on the overall performance of the nose are only based on one single measurement within each nasal segment. In vivo measurements within the entire nose are not feasible. These serious technical issues concerning in vivo measurements led to a large number of numerical simulation projects in the last few years providing novel information about the complex functions of the nasal airways. In general, numerical simulations merely calculate predictions in a computational model, e.g. a realistic nose model, depending on the setting of the boundary conditions. Therefore, numerical simulations achieve only approximations of a possible real situation. The aim of this review is the synopsis of the technical expertise on the field of in vivo nasal air conditioning, the novel information of numerical simulations and the current state of knowledge on the influence of nasal and sinus surgery on nasal air conditioning.

Low temperature results in decreased tension in decellularized human nasal mucosa

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effect of cooling on electrical field stimulation and norepinephrine-induced contraction in isolated hypertrophic human nasal mucosa

BACKGROUND

Exposure to cold causes cutaneous vasoconstriction to reduce body heat loss, while the nasal cavity warms up the inspired cold air. This suggests cooling might evoke a different response in nasal mucosa blood vessels than in cutaneous blood vessels. Thus, the aim of this study was to evaluate the effect of cooling (to 24 degrees C) on the vascular response of isolated nasal mucosa.

METHODS

An in vitro isometric contraction of nasal mucosa excised from patients suffered from chronic nasal congestion was continuously recorded. Either electrical field stimulation (EFS) or exogenous norepinephrine (NE) was applied to the turbinate mucosa strip at 37 and 24 degrees C, and the influence of cooling (to 24 degrees C) was evaluated.

RESULTS

EFS (1, 2, 4, and 8 Hz) produced frequency-dependent contractions at 37 and 24 degrees C. Cooling did not alter the magnitude but significantly prolonged the duration of EFS-induced contraction. Exogenous NE (10(-8) to 10(-4) M) produced concentration-dependent contractions at 37 and 24 degrees C. Cooling significantly enhanced the contractile responses evoked by NE between 3 x 10(-6) and 1 x 10(-4) M.

CONCLUSION

Cooling (to 24 degrees C) prolonged the EFS-induced and enhanced NE (3 x 10(-6) to 1 x 10(-4) M)-induced contraction of isolated human nasal mucosa.

Enhanced upper respiratory tract airflow and head fanning reduce brain temperature in brain-injured, mechanically ventilated patients: a randomized, crossover, factorial trial

BACKGROUND

Heat loss from the upper airways and through the skull are physiological mechanisms of brain cooling which have not been fully explored clinically.

METHODS

This randomized, crossover, factorial trial in 12 brain-injured, orally intubated patients investigated the effect of enhanced nasal airflow (high flow unhumidified air with 20 p.p.m. nitric oxide gas) and bilateral head fanning on frontal lobe brain temperature and selective brain cooling. After a 30 min baseline, each patient received the four possible combinations of the interventions--airflow, fanning, both together, no intervention--in randomized order. Each combination was delivered for 30 min and followed by a 30 min washout, the last 5 min of which provided the baseline for the next intervention.

RESULTS

The difference in mean brain temperature over the last 5 min of the preceding washout minus the mean over the last 5 min of intervention, was 0.15 degrees C with nasal airflow (P=0.001, 95% CI 0.06-0.23 degrees C) and 0.26 degrees C with head fanning (P<0.001, 95% CI 0.17-0.34 degrees C). The estimate of the combined effect of airflow and fanning on brain temperature was 0.41 degrees C. Selective brain cooling did not occur.

CONCLUSION

Physiologically, this study demonstrates that heat loss through the upper airways and through the skull can reduce parenchymal brain temperature in brain-injured humans and the onset of temperature reduction is rapid. Clinically, in ischaemic stroke, a temperature decrease of 0.27 degrees C may reduce the relative risk of poor outcome by 10-20%. Head fanning may have the potential to achieve a temperature decrease of this order.

Persistent allergic rhinitis and indoor air quality perception--an experimental approach

In order to compare patterns of indoor air perception, including perceptions of temperature, air movement, indoor air quality (IAQ), mental concentration, and comfort, 33 subjects either with persistent allergic rhinitis or controls were exposed to different temperatures and constant relative humidity in an experimental office environment. Results were obtained by means of a self-administered visual analogue scale, analyzed using mean score comparisons and principal component analysis. At 14 degrees C, the rhinitis group reported higher scores for sensations of air dryness than controls. At 18 degrees C, in the rhinitis group, there was a correlation between dry, stagnant air, and difficult mental concentration. This group also correlated heat, dry air, and poor IAQ, in contrast to the control group, which correlated comfort, easy mental concentration, and freshness. At 22 degrees C, the rhinitis group correlated heat, dryness, stagnant air, and overall discomfort. This group also correlated non-dry air, freshness, and comfort, whereas the control group correlated heat, humidity, good indoor air, freshness, and comfort. This study suggests that the rhinitis group perceives indoor temperatures of 14 degrees C as dryer than controls do, and that at 18 and 22 degrees C this group positively correlates different adverse perceptions of IAQ. By means of a self-administered questionnaire in an experimental condition, the present study compares subjective patterns of indoor air perception from individuals with respiratory allergy (allergic rhinitis) to control individuals. It reports different patterns of perception of indoor air quality (IAQ) between the two groups, suggesting that allergic individuals could have different IAQ perception.

Nasal conditioning in perennial allergic rhinitis after nasal allergen challenge

BACKGROUND

Antigen challenge in seasonal allergic rhinitis is considered to be associated with an increased ability of the nose to condition inspired air. In contrast, little is known about air conditioning after antigen challenge in perennial allergic rhinitis (PAR).

OBJECTIVE

The aims of this study were to investigate whether antigen challenge in PAR changes nasal air conditioning and to assess the relationship between nasal conditioning and nasal patency and geometry.

METHODS

Nineteen subjects with PAR were enrolled into this study. Measurement of nasal conditioning, active anterior rhinomanometry (AAR), acoustic rhinometry (AR), and clinical symptom evaluation were performed before and after nasal allergen challenge with allergen extracts from house dust mites.

RESULTS

Ten and 20 min after nasal allergen challenge, the total water content of the air measured in the nasopharynx and the water gradient across the nose were significantly higher in the nasal cavity in which the allergen extract was sprayed. The temperature on both sides of the nose increased non-significantly after nasal allergen challenge. No correlation to data obtained by AAR, AR, and clinical symptom evaluation after nasal allergen challenge was found.

CONCLUSION

We suggest that an increase in mucosal humidity due to the allergic provocation might be responsible for the increase in nasal conditioning capacity because no correlation to changes in nasal perimeter and patency was found.

New horizons in the management of allergy

Over the last year, the understanding of early childhood allergen exposures and their impact on the development of allergy has radically changed. This article reviews these epidemiologic discoveries, although they have not yet led to therapeutic initiatives.

The role of house dust mite elimination in the management of childhood asthma: an unresolved issue

Indoor allergens are likely to be direct environmental causes of asthma and mite exposure, and sensitization is the most important environmental risk factor for childhood asthma in temperate zones. Analagous to occupational asthma, allergen avoidance in asthmatic children sensitized and exposed to mite allergens is associated with a reduction in airway hyperresponsiveness and symptoms associated with improvement in lung function. The long-term effect of this strategy needs to be prospectively evaluated considering both the timing and duration of exposure, as well as the timing and duration of removal. In order to be successful, it is important to achieve and maintain a major reduction on allergen levels, for a long period of time.

Nasal mucosal temperature during respiration

One of the most important functions of the nose is heating the inspiratory air. The aim of the present study was to measure nasal mucosal temperature at defined intranasal sites during respiration, without interruption of nasal breathing. A total of 15 healthy volunteers was included in the study. A miniaturized thermocouple was used for continuous detection of the septal mucosal temperature in the nasal vestibule, the nasal valve area, the anterior turbinate area and the nasopharynx during respiration. The highest temperature values were measured at the end of expiration, the lowest values at the end of inspiration with a statistically significant difference (P < 0.005). Mean mucosal temperature ranged from 30.2 +/- 1.7 degrees C to 34.4 +/- 1.1 degrees C. Statistically there were significant differences between the detection sites during inspiration and expiration (P < 0.05). In our study, the temperature values of the nasal mucosa depend on the intranasal detection site and the respiratory cycle. We therefore conclude that whenever data of nasal mucosal temperature are published, it is absolutely essential to describe the precise site of detection and to give information about the time of detection in the respiratory cycle.

Supine position decreases the ability of the nose to warm and humidify air

We tested the hypothesis that decreasing nasal air volume (i.e., increasing nasal turbinate blood volume) improves nasal air conditioning. We performed a randomized, two-way crossover study on the conditioning capacity of the nose in six healthy subjects in the supine and upright position. Cold, dry air (CDA) was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before it entered and after it exited the nasal cavity. The total water gradient (TWG) across the nose was calculated and represents the nasal conditioning capacity. Nasal volume decreased significantly from baseline without changing the mucosal temperature when subjects were placed in the supine position (P < 0.01). TWG in supine position was significantly lower than that in upright position (P < 0.001). In the supine position, nasal mucosal temperature after CDA exposure was significantly lower than that in upright position (P < 0.01). Our data show that placing subjects in the supine position decreased the ability of the nose to condition CDA compared with the upright position, in contrast to our hypothesis.

Hot, humid air increases cellular influx during the late-phase response to nasal challenge with antigen

BACKGROUND

Inhalation of hot, humid air (HHA: 37 degrees C, > 95% relative humidity (RH)) partially inhibits the early response to nasal challenge with antigen.

OBJECTIVE

To investigate whether HHA inhibited the late-phase response to nasal challenge with antigen and increased hyper-responsiveness of the nasal mucosa to histamine.

METHODS

Twenty subjects with seasonal allergic rhinitis, outside of their allergy season, participated in a randomized, 2-way cross-over study. The subjects continuously breathed room air (25 degrees C, 30% RH) or HHA delivered via a face mask during the entire experiment. Subjects were challenged intranasally with antigen 1 h after beginning conditioning. The response was monitored by symptoms and nasal lavage at 2-h intervals after the last antigen challenge. Eight hours after antigen challenge, nasal challenge with histamine was performed.

RESULTS

Exposure to HHA significantly increased nasal mucosal temperature from baseline without affecting nasal secretion osmolality. HHA significantly inhibited antigen-induced sneezes, congestion, pruritus, and human serum albumin levels during the early response to antigen challenge. HHA exposure, however, was associated with an 8-fold increase in the eosinophil influx and a 15-fold increase in the levels of eosinophil cationic protein during the late-phase response compared to room air. There were no significant differences in nasal hyper-responsiveness to histamine during either exposure.

CONCLUSION

HHA partially decreases the early response to nasal challenge with antigen, but dramatically increases eosinophil influx. Increasing eosinophil number had no effects on the hyper-responsiveness to histamine. We speculate that the physical conditions of air differentially impact the stages of allergic inflammation.

The nasal passage of subjects with asthma has a decreased ability to warm and humidify inspired air

We previously showed that individuals with seasonal allergic rhinitis (SAR) had a reduced ability to condition air, which was improved by inflammation. We hypothesized that individuals with perennial allergic rhinitis (PAR) would condition air like SAR with inflammation. Because individuals with asthma usually have inflammation in the nose, we hypothesized that they would condition air like individuals with PAR. We performed a prospective, parallel study on 15 normal subjects, 15 subjects with SAR outside their allergy season, 15 subjects with PAR, and 15 subjects with asthma. Cold, dry air (CDA) was delivered to the nose and the temperature and humidity of the air were measured before entering and after exiting the nasal cavity. The total water gradient (TWG) was calculated and represents the nasal conditioning capacity. The TWG in the SAR group was significantly lower than that in normal subjects. There were no significant differences in TWG between the PAR and normal groups. Subjects with asthma had a significantly lower TWG than did normal subjects. There was a significant negative correlation between TWG and Aas score in the group with asthma (r(s) = -0.8, p = 0.0007). Our data show that subjects with asthma have a reduced ability of the nose to condition CDA compared with normal subjects, but which is similar to SAR out of season.

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.

Ipratropium bromide increases the ability of the nose to warm and humidify air

We have developed a method for measuring the temperature and relative humidity of air prior to and after nasal conditioning and used it to study the effect of treatment with ipratropium bromide on the ability of the nose to condition cold, dry air. We performed randomized, double-blind, placebo-controlled, two-way crossover studies and an open study in nonallergic subjects. The subjects were treated with ipratropium bromide (84 microgram) or normal saline solution sprayed into the nasal cavity 15 min before the measurement of nasal conditioning capacity. Cold, dry air was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before entering and after exiting the nasal cavity. The total water gradient across the nose was calculated and represents nasal conditioning capacity. Ipratropium bromide treatment significantly increased nasal conditioning capacity when compared with saline. Ipratropium bromide led to less reduction in the cold, dry air-induced decrease in the nasal volume (p < 0.05) without affecting the decrease in nasal surface temperature during cold, dry air exposure (p = 0.3). Our data show that ipratropium bromide increases the ability of the nose to condition cold, dry air. Thus, treating rhinitis with ipratropium bromide should not increase the burden for inspired air conditioning on the conducting pulmonary airways.