Reciprocity versus rhythmicity in spontaneous alternations of nasal airflow

Chief Complaint: Nasal Congestion

Nasal obstruction is the subjective perception and objective state of insufficient airflow through the nose. Nasal congestion, conversely, describes a state of not just inadequate airflow or obstructive phenomena but also pressure- and mucus-related states to the patient. Nasal receptors belonging to the transient receptor potential (TRP) protein family mediate the sense of nasal patency via the trigeminal nerve. The transient receptor potential melastatin-8 (TRPM8) responds to temperatures around 8°C to 22°C, and is stimulated by menthol and other cooling agents. The radiant effects of airflow create heat loss to activate these receptors and humans perceive this as nasal patency rather than the direct detection of airflow. The thermovascular state of the mucosa, in conditions such as rhinitis, influence TRPM8 activation. Nasal endoscopy can show signs of rhinitis and should be considered an essential part of the workup of nasal congestion. Efforts to relieve nasal congestion need to manage the mucosal state and surgery needs to ensures that the nasal cavity mucosa is exposed to the cooling effects of airflow rather than simply creating a passage to the nasopharynx.

Effect of ambient temperature and respiration rate on nasal dominance: preliminary findings from a nostril-specific wearable

The nasal dominance (ND) determination is crucial for nasal synchronized ventilator, optimum nasal drug delivery, identifying brain hemispheric dominance, nasal airway obstruction surgery, mindfulness breathing, and for possible markers of a conscious state. Given these wider applications of ND, it is interesting to understand the patterns of ND with varying temperature and respiration rates. In this paper, we propose a method which measures peak-to-peak temperature oscillations (difference between end-expiratory and end-inspiratory temperature) for the left and right nostrils during nasal breathing. These nostril-specific temperature oscillations are further used to calculate the nasal dominance index (NDI), nasal laterality ratio (NLR), inter-nostril correlation, and mean of peak-to-peak temperature oscillation for inspiratory and expiratory phase at (1) different ambient temperatures of 18 °C, 28 °C, and 38 °C and (2) at three different respiration rate of 6 bpm, 12 bpm, and 18 bpm. The peak-to-peak temperature (Tpp) oscillation range (averaged across participants;n= 8) for the left and right nostril were 3.80 ± 0.57 °C and 2.34 ± 0.61 °C, 2.03 ± 0.20 °C and 1.40 ± 0.26 °C, and 0.20 ± 0.02 °C and 0.29 ± 0.03 °C at the ambient temperature of 18 °C, 28 °C, and 38 °C respectively (averaged across participants and respiration rates). The NDI and NLR averaged across participants and three different respiration rates were 35.67 ± 5.53 and 2.03 ± 1.12; 8.36 ± 10.61 and 2.49 ± 3.69; and -25.04 ± 14.50 and 0.82 ± 0.54 at the ambient temperature of 18 °C, 28 °C, and 38 °C respectively. The Shapiro-Wilk test, and non-parametric Friedman test showed a significant effect of ambient temperature conditions on both NDI and NLR. No significant effect of respiration rate condition was observed on both NDI and NLR. The findings of the proposed study indicate the importance of ambient temperature while determining ND during the diagnosis of breathing disorders such as septum deviation, nasal polyps, nosebleeds, rhinitis, and nasal fractions, and in the intensive care unit for nasal synchronized ventilator.

How do phosphodiesterase-5 inhibitors affect cancer? A focus on glioblastoma multiforme

Since the discovery of phosphodiesterase-5 (PDE5) enzyme overexpression in the central nervous system (CNS) malignancies, investigations have explored the potential capacity of current PDE5 inhibitor drugs for repositioning in the treatment of brain tumors, notably glioblastoma multiforme (GBM). It has now been recognized that these drugs increase brain tumors permeability and enhance standard chemotherapeutics effectiveness. More importantly, studies have highlighted the promising antitumor functions of PDE5 inhibitors, e.g., triggering apoptosis, suppressing tumor cell growth and invasion, and reversing tumor microenvironment (TME) immunosuppression in the brain. However, contradictory reports have suggested a pro-oncogenic role for neuronal cyclic guanosine monophosphate (cGMP), indicating the beneficial function of PDE5 in the brain of GBM patients. Unfortunately, due to the inconsistent preclinical findings, only a few clinical trials are evaluating the therapeutic value of PDE5 inhibitors in GBM treatment. Accordingly, additional studies should be conducted to shed light on the precise effect of PDE5 inhibitors in GBM biology regarding the existing molecular heterogeneities among individuals. Here, we highlighted and discussed the previously investigated mechanisms underlying the impacts of PDE5 inhibitors in cancers, focusing on GBM to provide an overview of current knowledge necessary for future studies.

Correlation between Rhinometric Measurement Methods in Healthy Young Adults

The most common rhinometric measurement methods used in modern rhinology are acoustic rhinometry, rhinomanometry, and nasal peak expiratory flow (PEF) rate. In this prospective study, we wanted to clarify whether the parameters given by these three methods in the same subject support each other and can be used simultaneously in clinical practice. We also wanted to define the dimensions of normal nasal geometry and function based on these three methods. The rhinometric measurements were done in 249 healthy white subjects consisting of 171 women and 78 men. The geometry was analyzed with regard to body mass index (BMI) and smoking habits. The result could be used as some kind of reference value for the same kind of patient cohort as when rhinological pathology is investigated. The measurements obtained by acoustic rhinometry showed only statistically significant correlations between the measured volume and minimal cross-sectional area in the nasal cavities (r = 0.959). Rhinomanometry showed only a statistically significant correlation between the measured resistance in expiration and inspiration (r = 0.977). Acoustic rhinometry, rhinomanometry, and nasal PEF did not show any correlations and the BMI did not have any effect on the results. Although the smoking group was relatively small in this cohort, the rhinometric methods showed smaller nasal cavity volume, higher resistance, and lower nasal PEF values. Based on these results, we recommend the use of these three rhinometric methods as independent instruments in rhinological examinations. However, in the pathological nose, e.g., smokers, the methods show equal changes in measurements. It is important to measure at least acoustic rhinometry and rhinomanometry at the same time in clinical practice to achieve good quality of examinations.

Measuring and Characterizing the Human Nasal Cycle

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

The influences of age on olfaction: a review

Decreased olfactory function is very common in the older population, being present in over half of those between the ages of 65 and 80 years and in over three quarters of those over the age of 80 years. Such dysfunction significantly influences physical well-being and quality of life, nutrition, the enjoyment of food, as well as everyday safety. Indeed a disproportionate number of the elderly die in accident gas poisonings each year. As described in this review, multiple factors contribute to such age-related loss, including altered nasal engorgement, increased propensity for nasal disease, cumulative damage to the olfactory epithelium from viral and other environmental insults, decrements in mucosal metabolizing enzymes, ossification of cribriform plate foramina, loss of selectivity of receptor cells to odorants, changes in neurotransmitter and neuromodulator systems, and neuronal expression of aberrant proteins associated with neurodegenerative disease. It is now well established that decreased smell loss can be an early sign of such neurodegenerative diseases as Alzheimer's disease and sporadic Parkinson's disease. In this review we provide an overview of the anatomy and physiology of the aging olfactory system, how this system is clinically evaluated, and the multiple pathophysiological factors that are associated with its dysfunction.

A Review of the Effects of Expansion of the Nasal Base on Nasal Airflow and Resistance

PURPOSE

The purpose of this article is to inform the reader of the current literature regarding nasal airflow resistance. The anatomy and physiology of nasal airflow resistance will be examined and the known effects of widening of the nasal airway upon airflow will be described.

MATERIALS AND METHODS

This article is a review of the current literature regarding nasal airflow and resistance and the effects of widening of the nasal base. No patient data were collected.

RESULTS

The literature shows that nasal airflow resistance can be changed by surgical manipulation and by rapid palatal expansion, but that the effects on airflow resistance and future growth and development are unpredictable.

CONCLUSION

Patients with a maxilla that is constricted in the transverse dimension and nasal airflow problems may benefit from expansion of the nasal base. The resultant effects upon nasal airflow resistance and subsequent growth and development are unpredictable and therefore airflow issues alone may not be a primary reason to increase the transverse dimension of the nasal base.

Sleep, breathing and the nose

During sleep there is a discrete fall in minute ventilation and an associated increase in upper airway resistance. In normal subjects, the nasal part of the upper airway contributes only little to the elevation of the total resistance, which is mainly the consequence of pharyngeal narrowing. Yet, swelling of the nasal mucosa due to congestion of the submucosal capacitance vessels may significantly affect nasal airflow. In many healthy subjects an alternating pattern of congestion and decongestion of the nasal passages is observed. Some individuals demonstrate congestion of the ipsilateral half of the nasal cavity when lying down on the side. Nasal diseases, including structural anomalies and various forms of rhinitis, tend to increase nasal resistance, which typically impairs breathing via the nasal route in recumbency and during sleep. A role of nasal obstruction in the pathogenesis of sleep-disordered breathing has been implicated by many authors. While it proves difficult to show a relationship between the degree of nasal obstruction and the number of disturbed breathing events, the presence of nasal obstruction will most likely have an impact on the severity of sleep-disordered breathing. Identification of nasal obstruction is important in the diagnostic work-up of patients suffering from snoring and sleep apnea.

The application of electroencephalographic techniques to the study of human olfaction: a review and tutorial

The use of a variety of electrophysiological techniques to determine the effects of odor on the nervous system is reviewed. Methods and problems associated with the collection of on-going EEG, chemosensory event-related potentials, and contingent negative variation data are discussed in depth as is the use of odors as modulators of brain potentials produced by other senses. In addition, the advantages of several seldom used EEG analysis techniques are discussed with respect to the unique problems of understanding olfaction.

Spontaneous changes of unilateral nasal airflow in man. A re-examination of the 'nasal cycle'

It is now over 100 years since Kayser (Archiv für Laryngol Rhinol 1895; 3: 101-120) first reported in the scientific literature that the human nasal passages exhibit spontaneous changes in unilateral nasal airway resistance, yet our understanding of this unusual phenomenon is still very confused. Spontaneous, reciprocal changes in unilateral nasal resistance are often referred to as a "nasal cycle" and although this term is now commonly used to describe spontaneous changes in nasal resistance in man and animals, there is little evidence for any true periodicity. A major problem in increasing our knowledge and understanding of the so-called "nasal cycle" is that most studies have relied on simple descriptions of the changes in nasal resistance and have not developed any numerical parameters to quantify the changes in resistance over time. This lack of definition of what actually constitutes a nasal cycle has meant that the literature of the present day generally accepts the views put forward by Heetderks (Am J Med Sci 1927; 174; 231-244) and Stoksted (Acta Otolaryngol (Stockh) 1953; Suppl 109: 159-175) that around 80% of the healthy population exhibit a regular cycle. In order to define the characteristics of the spontaneous changes in nasal airway resistance we have used numerical measures of reciprocity and also developed a measurement of the division of airflow between the nasal passages over time. With these two parameters it is possible to describe the nature of the spontaneous changes in airflow in numerical terms and to define what exactly constitutes a nasal cycle. Fifty-two volunteers underwent hourly measurement of unilateral nasal airflow for 8 h. For each volunteer, two values were derived from the graph of unilateral nasal airflows against time; the correlation coefficient between unilateral airflows (r) and the airflow distribution ratio between the two nasal airways (ADR). The spread of different types of airflow pattern (nasal cycle) throughout the population was illustrated by plotting r against ADR for each subject. A nasal cycle was defined as having an r value between -0.6 and -1.0, and an ADR value between 0.7 and 1.0. Only 21% (11 of the 52 volunteers) exhibited airflow patterns that could be defined as a nasal cycle in these terms. This finding contradicts the generally accepted, but undefined, view that around 80% of the population exhibit a regular nasal cycle. The numerical definition of a nasal cycle in terms of both reciprocity and airflow distribution, as described in this paper may help to clarify our understanding of this interesting phenomenon and allow rhinologists to describe the spontaneous changes in nasal airflow in more exact terms than have been used previously in the literature.

Changes in the amplitude of the nasal cycle associated with symptoms of acute upper respiratory tract infection

Nasal airflow is normally asymmetrical and subject to spontaneous reciprocal changes which are often referred to as the 'nasal cycle'. The nature of these spontaneous changes in nasal resistance is poorly understood and little information is available about how they are affected by nasal disease. In order to understand the changes in nasal resistance in health and disease it is important to record unilateral resistance rather than express results as total nasal resistance. Unilateral resistance is subject to continuous reciprocal changes and therefore new measurements were developed in this study in order to quantify the nasal resistance of each nasal passage. Twelve human subjects (age 19-38) with symptoms of acute respiratory tract infection (URTI) were recruited for the study which involved serial measurements of unilateral nasal airway resistance using the technique of posterior rhinomanometry over a period of six hours. Measurements were made on one day when subjects had symptoms of URTI and then repeated 6-8 weeks later when subjects were healthy. The results of this study show that all of the subjects exhibited spontaneous reciprocal changes in nasal airway resistance on both study days but that there was a significant increase in the amplitude of the changes in resistance when the subjects had symptoms of URTI with one nasal passage often becoming severely congested. In order to quantify the amplitude of the reciprocal changes in nasal resistance two new measures were used. The minimum and maximum nasal airway resistance recorded for each nasal passage during the six hour recording period (MIN NAR and MAX NAR). Mean MIN NAR with URTI was 0.4 Pa cm3s +/- 0.07 which was not significantly different from mean MIN NAR in health which was 0.36 Pa cm3s +/- 0.05 (p = 0.22, n = 20). The mean MAX NAR during URTI was 2.44 Pa cm3s +/- 0.38 and this decreased significantly to 1.36 +/- 0.17 when recorded during healthy conditions (p = 0.01, n = 20). The increased amplitude of spontaneous reciprocal changes in nasal airway resistance associated with symptoms of URTI is proposed to be due to an increased filling pressure to the nasal venous sinusoids associated with a nasal inflammatory response. A model is proposed to explain the role of the nasal sympathetic vasoconstrictor tone and nasal venous filling pressure in the control of nasal airway resistance and to help explain the periods of unilateral nasal obstruction often associated with allergic and infective rhinitis.

The effect of pressure and warmth applied to the axilla on unilateral nasal airway resistance and facial skin temperature

The effect of pressure, warmth, and control stimuli applied to the axilla and lateral chest wall on unilateral nasal airway resistance and facial skin temperature was investigated in 60 healthy adults. Nasal resistance was measured by posterior rhinomanometry and skin temperature with an infrared thermometer. A significant increase in unilateral nasal resistance ipsilateral to the applied stimulus was seen with both pressure and warmth (p = 0.006, p = 0.02). A decrease in unilateral nasal resistance contralateral to the stimulus was seen in both these groups, but this was not significant (p = 0.45, p = 0.81). The control stimulus showed a non-significant increase in unilateral nasal resistance ipsilateral to the applied stimulus (p = 0.55), and a significant rise in unilateral nasal resistance on the contralateral side (p = 0.008). There were no significant differences between the ipsilateral and contralateral facial skin temperatures before or after the application of a unilateral pressure, warm or control stimulus. A significant bilateral increase in facial temperature was observed during the course of the experiment in all three groups. The mechanisms of induced changes in unilateral nasal resistance are discussed. The results increase our knowledge of the corporo-nasal reflex and demonstrate that the reciprocal changes in sympathetic tone to the nasal capacitance blood vessels are independent from any parallel reflex changes in sympathetic tone to cutaneous blood vessels.

The relationship of cortical activation to alternating autonomic activity

It has been proposed that it is possible to selectively activate the cerebral hemispheres, thereby enhancing lateralized cognitive abilities. A proposed method of achieving selective activation is by altering nasal congestion/decongestion (nasal cycle), which is believed to effect a contralateral change in hemispheric activation through the autonomic nervous system (ANS). This hypothesis was tested in 4 right-handed male and 6 right-handed female undergraduate students. Subjects were untrained in specific breathing techniques but were aware of the experimental hypothesis. Four 1 min samples of EEG were recorded in each of 4 experimental conditions in which nasal decongestion was altered by having subjects lie in the lateral recumbent position and occluding the contralateral nare. Cortical activation and laterality were examined using ratios of the low beta (12-18 Hz) and high alpha (10-12 Hz) bandwidths relative to each other and between hemispheres. Repeated measures ANOVAs showed non-significant changes in the alpha and beta bandwidths across the 4 experimental conditions. Although changes in hemispheric activation have been postulated for all subjects, this study does not support such changes in subjects untrained in breathing techniques.