Effect of the cooling sensation induced by olfactory stimulation by L-menthol on dyspnoea: a pilot study

Supramolecular Structure of the β-Cyclodextrin Metal-Organic Framework Optimizes Iodine Stability and Its Co-delivery with l-Menthol for Antibacterial Applications

The spread of upper respiratory tract (URT) infections harms people's health and causes social burdens. Developing targeted treatment strategies for URT infections that exhibit good biocompatibility, stability, and strong antimicrobial effects remains challenging. The dual antimicrobial and antiviral effects of iodine (I2) in combination with the cooling sensation of l-menthol in the respiratory tract can simultaneously alleviate URT inflammation symptoms. However, as both I2 and l-menthol are volatile, addressing stability issues is crucial. In this study, a potassium iodide β-cyclodextrin metal-organic framework [β-CD-POF(I)] with appropriate particle size was used to coload and deliver I2 and l-menthol. Primarily, β-CD-POF(I) was employed as the most efficient carrier to significantly enhance the stability of I2, surpassing any other known protection strategies in the pharmaceutical field (CD complexations, PVP conjugations, and cadexomer iodine). The mechanism underlying the improvement in stability of I2 by β-CD-POF(I) was investigated through scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and molecular docking. The results revealed that the key processes involved in improving stability were the inclusion of I2 by β-CD cavities in β-CD-POF(I) and the formation of polyiodide anion between iodine ions and I2. Furthermore, the potential of β-CD-POF(I) to load and deliver drugs was validated, and coloading of l-menthol and I2 demonstrated reliable stability. β-CD-POF(I) achieved a rate of URT deposition ≥95% in vitro, and the combined antibacterial effects of coloaded I2 and l-menthol was better than I2 or PVP-I alone, with no irritation noted following URT administration in rabbits. Therefore, the stable coloading of drugs by β-CD-POF(I), leading to enhanced antimicrobial effects, provides a new strategy for treating URT infections.

Dyspnoea relief as an inherent benefit of high flow nasal cannula therapy: A laboratory randomized trial in healthy humans

BACKGROUND AND OBJECTIVE

Persistent dyspnoea is a public health issue for which the therapeutic arsenal is limited. This study tested high-flow nasal cannula therapy (HFNT) as a means to alleviate experimental dyspnoea.

METHODS

Thirty-two healthy subjects underwent an experimental dyspnoea induced by thoracoabdominal elastic loading. HFNT was administered with alternately FiO2 of 100% (HFNT100) or 21% (HFNT21). The sensory (S-VAS) and affective (A-VAS) components of dyspnoea, transcutaneous CO2 pressure (PtcCO2 ), pulse-oximetry oxygen saturation (SpO2 ), heart rate, respiratory rate and skin galvanometry were monitored continuously. Three experimental sessions of 8 min were conducted: the first session consisted in familiarization with the experimental dyspnoea and the next two sessions tested the effects of HFNT100 and HFNT21 alternatively in a randomized order.

RESULTS

HFNT21 and HFNT100 significantly reduced dyspnoea, respectively of ∆A-VAS = 0.80 cm [-0.02-1.5]; p = 0.007 and ∆A-VAS = 1.00 cm [0.08-1.75]; p < 0.0001; ∆S-VAS = 0.70 cm [-0.15-1.98]), p < 0.0001 and ∆S-VAS = 0.70 cm [0.08-1.95]), p = 0.0002) with no significant difference between HFNT21 and HFNT100. HFNT did not significantly alter the respiratory rate or the heart rate, reduced PtcCO2 only on room air and GSR under both experimental conditions.

CONCLUSION

HFNT was associated with a statistically significant reduction in the intensity of the sensory and affective components of dyspnoea, independent of oxygen addition. This relief of laboratory dyspnoea could result from a reduction of afferent-reafferent mismatch.

L-menthol administration facilitates breathing comfort during exhaustive endurance running and improves running capacity in well-trained runners: A randomized crossover study

ABSTRACTThis study aimed to clarify the contribution of L-menthol administration to endurande exercise capacity. Thirteen male runners (age, 35.8 ± 7.8 years; peak oxygen uptake, 62.7 ± 6.8 mL kg-1 min-1) ran on treadmills at fixed intensities of their anaerobic thresholds to exhaustion. All participants underwent three trials-water ingestion (W-IG), L-menthol mouth rinsing (M-MR), and L-menthol ingestion (M-IG)- in a random order every 5 min while running. Breathing comfort (BC) was measured immediately after fluid intake. Dyspnea threshold against external inspiratory resistance was examined before and after the running test. The running time with M-IG (1683.9 ± 520.3 s) was longer than that with W-IG (1410.2 ± 465.9 s, effect size [ES] = 0.55). BC with M-IG (2.00 ± 0.74) was higher than that with W-IG (0.42 ± 0.79) at exhaustion (ES > 2.00). The dyspnea threshold after running decreased to 19.2 ± 7.6 cm H₂O L-1 s-1 with W-IG, whereas that with M-MR (26.2 ± 6.5 cm H₂O L-1 s-1) and M-IG (29.2 ± 2.8 cm H₂O L-1 s-1) remained high (p for interaction < 0.001). M-IG facilitated BC during running, improved endurance capacity, and prevented decreases in the dyspnea threshold against external inspiratory resistance after exhaustive running.HighlightsL-menthol ingestion facilitated breathing comfort during high intensity endurance running and improved exhaustive endurance running capacity.Even after exhaustion, L-menthol solution relieved dyspnea sensitivity against external inspiratory resistance.L-menthol ingestion might help athletes improve their endurance running capacity.

L-Menthol Olfactory Stimulation Reduced Dyspnea Sensation during the 6 min Walk Test in Patients with Chronic Breathlessness Syndrome: A Pilot Study

There are very limited methods of relieving dyspnea that are independent of the causative disease. L-menthol olfactory stimulation is reported to be effective for dyspnea during exercise and inspiratory resistance. Therefore, we examined the effects of L-menthol olfactory stimulation on exertional dyspnea during the 6 min walking distance test (6MWT) in patients with chronic breathlessness syndrome. The subjects who consented to the study were divided into two groups. In Group A, the first 6MWT was performed as usual (placebo) while wearing a surgical mask, and the second 6MWT was performed under the L-menthol condition. In Group B, the first 6MWT was performed under the L-menthol condition, and the second 6MWT was performed as a placebo. A total of 16 subjects (70.8 ± 9.5 years) were included in the analysis. As for the effect of reducing dyspnea, a significant difference was observed in Group A patients who underwent the L-menthol condition in the second 6MWT (p = 0.034). In the comparison of the 6 min walking test under the L-menthol condition and the placebo, the modified Borg scale gain was significantly different between the L-menthol condition and the placebo (p = 0.007). Our results suggested that the L-menthol olfactory stimulation reduced dyspnea on exertion in patients with chronic breathlessness syndrome.

Distinguishing science from pseudoscience in commercial respiratory interventions: an evidence-based guide for health and exercise professionals

Respiratory function has become a global health priority. Not only is chronic respiratory disease a leading cause of worldwide morbidity and mortality, but the COVID-19 pandemic has heightened attention on respiratory health and the means of enhancing it. Subsequently, and inevitably, the respiratory system has become a target of the multi-trillion-dollar health and wellness industry. Numerous commercial, respiratory-related interventions are now coupled to therapeutic and/or ergogenic claims that vary in their plausibility: from the reasonable to the absurd. Moreover, legitimate and illegitimate claims are often conflated in a wellness space that lacks regulation. The abundance of interventions, the range of potential therapeutic targets in the respiratory system, and the wealth of research that varies in quality, all confound the ability for health and exercise professionals to make informed risk-to-benefit assessments with their patients and clients. This review focuses on numerous commercial interventions that purport to improve respiratory health, including nasal dilators, nasal breathing, and systematized breathing interventions (such as pursed-lips breathing), respiratory muscle training, canned oxygen, nutritional supplements, and inhaled L-menthol. For each intervention we describe the premise, examine the plausibility, and systematically contrast commercial claims against the published literature. The overarching aim is to assist health and exercise professionals to distinguish science from pseudoscience and make pragmatic and safe risk-to-benefit decisions.

Impact of trigeminal and/or olfactory nerve stimulation on measures of inspiratory neural drive: Implications for breathlessness

The perception of breathlessness is mechanistically linked to the awareness of increased inspiratory neural drive (IND). Stimulation of upper airway cold receptors on the trigeminal nerve (TGN) with TGN agonists such as menthol or cool air to the face/nose has been hypothesized to reduce breathlessness by decreasing IND. The aim of this systematic scoping review was to identify and summarize the results of studies in animals and humans reporting on the impact of TGN stimulation or blockade on measures of IND. Thirty-one studies were identified, including 19 in laboratory animals and 12 in human participants. Studies in laboratory animals consistently reported that as TGN activity increased, measures of IND decreased (e.g., phrenic nerve activity). In humans, stimulation of the TGN with a stream of cool air to the face/nose decreased the sensitivity of the ventilatory chemoreflex response to hypercapnia. Otherwise, TGN stimulation with menthol or cool air to the face/note had no effect on measures of IND in humans. This review provides new insight into a potential neural mechanism of breathlessness relief with selected TGN agonists.

Impact of trigeminal nerve and/or olfactory nerve stimulation on activity of human brain regions involved in the perception of breathlessness

Breathlessness is a centrally processed symptom, as evidenced by activation of distinct brain regions such as the insular cortex and amygdala, during the anticipation and/or perception of breathlessness. Inhaled L-menthol or blowing cool air to the face/nose, both selective trigeminal nerve (TGN) stimulants, relieve breathlessness without concurrent improvements in physiological outcomes (e.g., breathing pattern), suggesting a possible but hitherto unexplored central mechanism of action. Four databases were searched to identify published reports supporting a link between TGN stimulation and activation of brain regions involved in the anticipation and/or perception of breathlessness. The collective results of the 29 studies demonstrated that TGN stimulation activated 12 brain regions widely implicated in the anticipation and/or perception of breathlessness, including the insular cortex and amygdala. Inhaled L-menthol or cool air to the face activated 75% and 33% of these 12 brain regions, respectively. Our findings support the hypothesis that TGN stimulation contributes to breathlessness relief by altering the activity of brain regions involved in its central neural processing.

[The role of the physiotherapist in the assessment and management of dyspnea]

The role of the physiotherapist in the assessment and management of dyspnea. Dyspnea is the most common symptom in cardio-respiratory diseases. Recently improved comprehension of dyspnea mechanisms have underlined the need for three-faceted assessment. The three key aspects correspond to the "breathing, thinking, functioning" clinical model, which proposes a multidimensional - respiratory, emotional and functional - approach. Before initiating treatment, it is essential for several reasons to assess each specific case, determining the type of dyspnea affecting the patient, appraising the impact of shortness of breath, and estimating the effectiveness of the treatment applied. The physiotherapist has a major role to assume in the care of dyspneic patients, not only in assessment followed by treatment but also as a major collaborator in a multidisciplinary team, especially with regard to pulmonary rehabilitation. The aim of this review is to inventory the existing assessment tools and the possible physiotherapies for dyspnea, using a holistic approach designed to facilitate the choice of techniques and to improve quality of care by fully addressing the patient's needs.

Breathing control, brain, and bodily self-consciousness: Toward immersive digiceuticals to alleviate respiratory suffering

Breathing is peculiar among autonomic functions through several characteristics. It generates a very rich afferent traffic from an array of structures belonging to the respiratory system to various areas of the brain. It is intimately associated with bodily movements. It bears particular relationships with consciousness as its efferent motor control can be automatic or voluntary. In this review within the scope of "respiratory neurophysiology" or "respiratory neuroscience", we describe the physiological organisation of breathing control. We then review findings linking breathing and bodily self-consciousness through respiratory manipulations using virtual reality (VR). After discussing the currently admitted neurophysiological model for dyspnea, as well as a new Bayesian model applied to breathing control, we propose that visuo-respiratory paradigms -as developed in cognitive neuroscience- will foster insights into some of the basic mechanisms of the human respiratory system and will also lead to the development of immersive VR-based digital health tools (i.e. digiceuticals).

Limitations of a 6-minute-walk test to assess the efficacy of menthol for breathlessness

Walking is a vital component of physical activity in patients with chronic obstructive pulmonary disease (COPD). Exertional multidimensional breathlessness in daily life can reduce walking speed and time in patients with established COPD [1]. Improvement in breathlessness beyond a minimal clinically significant difference brought about by pulmonary rehabilitation, pharmaceutical bronchodilators and opioids has been reported [2–4]. However, despite guideline-directed disease-specific therapy, some patients with COPD experience residual breathlessness. Therefore, the application of a novel symptom-based treatment that is widely available will benefit patients with long-term breathlessness.

l-Menthol is a novel treatment option for breathlessness in patients with COPD. However, the clinical application of menthol for the treatment of exertional breathlessness in these patients warrants further research.https://bit.ly/3D6rLiJ

Hand-held fans: Physical Properties and Perceptions of Patients with COPD

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) may remain breathless despite optimal medical treatment. Hand-held fans (HHFs) are recommended to relieve breathlessness, but little is known about physical properties of different fans and the impact HHF properties may have on patient perceptions of fans.

OBJECTIVE

To describe the physical properties of HHFs and investigate the relationship of these properties to patient fan preference.

METHODS

We recruited 33 participants with COPD who were attending a pulmonary rehabilitation program. Participants trialled 5 HHFs in random order. Participants rated perceived airflow, pleasantness of airflow, noisiness, and ease of use of each fan using a 1-10 numerical rating scale (NRS). After trialling all 5 fans, participants ranked each HHF from best (5 arbitrary units; a.u.) to worst (1 a.u.). Rankings for each fan were tallied to produce total HHF scores (T-HHF; maximum=165 a.u.). Objective measurements were made of sound intensity (dB; sound level meter), airflow between 5cm and 30cm from the middle of the fan (anemometer), blade rotation speed, blade size and total fan weight. We assessed the strength of association of T-HHF scores against mean NRS values using Spearman correlation coefficients and used linear regression to compare measured to perceived airflow, and noisiness to sound intensity.

RESULTS

Participants were 68.5 ± 8.9 years (mean ± SD), 63% male, with a median FEV₁ of 0.99L(IQR 0.76-1.31L). There was considerable variability between the 5 fans tested in terms of participant perceptions and physical properties with an almost 5-fold difference in air velocity at 30cm and a 3-fold difference in blade rotation speed. The most preferred fan had a T-HHF score of 140 and had the highest airflow (1.9 m/s) measured at 30cm. T-HHF score positively correlated with pleasantness of airflow (r = 0.46; P < 0.001), perceived airflow (r=0.58; P<0.001) and airflow velocity at 30cm from fan blades (r=1.0; P = 0.02). There were positive linear relationships between fan airflow velocity and perceived air amount, and between measured sound intensity and perceived noisiness(both P<0.001). Women reported significantly higher perceived airflow than men (P < 0.001).

CONCLUSIONS

The physical properties of the five included HHFs are quite distinct. Patient preference was related to pleasantness of airflow, perceived airflow, and measured airflow at 30cm. Gender differences in perceived airflow were noted. Future research should explore the relationship between HHF characteristics and relief of breathlessness.

Dyspnea

The clinical term dyspnea (a.k.a. breathlessness or shortness of breath) encompasses at least three qualitatively distinct sensations that warn of threats to breathing: air hunger, effort to breathe, and chest tightness. Air hunger is a primal homeostatic warning signal of insufficient alveolar ventilation that can produce fear and anxiety and severely impacts the lives of patients with cardiopulmonary, neuromuscular, psychological, and end-stage disease. The sense of effort to breathe informs of increased respiratory muscle activity and warns of potential impediments to breathing. Most frequently associated with bronchoconstriction, chest tightness may warn of airway inflammation and constriction through activation of airway sensory nerves. This chapter reviews human and functional brain imaging studies with comparison to pertinent neurorespiratory studies in animals to propose the interoceptive networks underlying each sensation. The neural origins of their distinct sensory and affective dimensions are discussed, and areas for future research are proposed. Despite dyspnea's clinical prevalence and impact, management of dyspnea languishes decades behind the treatment of pain. The neurophysiological bases of current therapeutic approaches are reviewed; however, a better understanding of the neural mechanisms of dyspnea may lead to development of novel therapies and improved patient care.

Relieving from Breathlessness in the Wind: A Meta-Analysis and Subjective Report of Effectiveness of Fan Blowing in Patients with Cardiorespiratory Diseases or Cancer

OBJECTIVES

Breathlessness is common among terminally ill patients with cardiorespiratory disease or cancer. The experience may induce secondary physiological and behavioral responses that limit patient well-being and independence and cause emotional distress.

METHODS

We conducted a meta-analysis on randomized controlled trials (RCTs) that examined the effectiveness of fan blowing on breathlessness among patients with cardiorespiratory diseases or cancer. The PubMed, Cochrane Library, Embase, SCOPUS, and CINAHL databases were searched to retrieve potential articles. The primary outcome was breathlessness severity. The secondary outcomes were SpO₂, anxiety, depression, and quality of life. Also, we presented the changes of vital signs and subjective feeling of a male patient who used fan blowing for relieving his breathlessness.

RESULTS

Eight RCTs were available for analysis. The pooled results demonstrated no significant difference in breathlessness severity between fan-to-face blowing and control methods (standard mean difference: -0.21, 95% confidence interval: -.59 to .17); however, a significant reduction in breathlessness severity was observed in the short-time intervention compared with long-time intervention. A trend occurred toward significance in the reduction of respiratory rate in fan-to-face blowing compared with control methods (MD: -.64, 95% CI: -1.37 to .09). No differences were observed between groups in oxygen saturation, anxiety, depression, or QoL. The male patient who used fan blowing showed an improved vital signs and a satisfied subjective feeling.

CONCLUSIONS

Consistent short-time fan-to-face blowing is effective for relieving breathlessness among conscious terminally ill patients with cardiorespiratory diseases or cancer. The use of this convenient method for relieving breathlessness symptoms in terminally ill patients is recommended.

l-Menthol - a new treatment for breathlessness?

PURPOSE OF REVIEW

In patients with advanced chronic obstructive pulmonary disease (COPD), it is challenging to treat breathlessness. In addition, novel palliative interventions are required for multiple perspectives of breathlessness that may still be present after disease-specific therapies. This review provides an overview of the mechanisms and effects of l-menthol on breathlessness by covering the latest relevant papers.

RECENT FINDINGS

A literature review identified one randomized controlled trial assessing the effect of l-menthol on relieving breathlessness in patients with COPD. It has been reported that the mechanism of relieving breathlessness partly involves stimulation of the trigeminal nerve by the cooling sensation of l-menthol, which gives a cognitive illusion of inspiratory flow perception. The effect of l-menthol on breathlessness caused by exertion has been reported in healthy subjects but not yet in patients with breathlessness.

SUMMARY

The effect of l-menthol on the sensory-emotional dimensions of laboratory-induced breathlessness in patients with COPD has been described in a clinical trial. Further studies are warranted to investigate its application to inspiratory muscle training and its effects in combination with exercise training.

Short-term effects of menthol on walking dyspnoea in patients with COPD: a randomised, single blinded, cross-over study

Chewing menthol gum prior to exercise is a safe, easy-to-implement, low-cost, non-pharmacologic intervention that provides a reduction in dyspnoea in a third of patients and decreases the perception of discomfort during exercise in two-thirds of patients https://bit.ly/3FoFHp1.

Medical aromatherapy in geriatric syndrome

Geriatric syndromes are symptoms and signs, such as falls, incontinence, delirium, pressure ulcers, dysphagia and so on, that often threaten the independence of older adults, rather than the disease itself. Although the syndromes are very common in older people, it is difficult to treat those by modern medicine due to their complexity. To mitigate the intractable geriatric symptoms, we review the efficacy of aromatherapy, especially for dysphagia, dyspnea, cognitive dysfunction and falls in geriatric syndrome. Olfactory stimulation using a volatile black pepper oil on institutional residents improved the swallowing reflex, which is a crucial risk factor of aspiration pneumonia. Brain imaging study showed that olfactory stimulation using volatile black pepper oil activated cerebral regions of the anterior cingulate and the insular cortex, which play a role in controlling appetite and swallowing. Also, aromatherapy with volatile l-menthol decreased the sense of dyspnea and improved the efficacy of exercise therapy. The fragrance of the combination of rosemary and lemon oils in the morning, and the combination of lavender and orange oils in the night-time were reported to improve cognition and behavioural and psychological symptoms of dementia, respectively. Also, the combination of lavender and lemon balm oils was reported to be effective for irritability-related agitation in older adults. Furthermore, aromatherapy with lavender fragrance could improve both static and dynamic balance, resulting in a reduction in the number of fallers and the incidence rate in older people. Thus, aromatherapy is a promising remedy for geriatric syndrome. Geriatr Gerontol Int 2021; 21: 377-385.

Effect of facial skin cooling induced by a handheld fan on the cough reflex threshold and urge to cough induced by citric acid

Chronic cough is a condition that impairs the quality of life of affected patients and may persist despite optimal intervention. Thus, a novel therapeutic approach with broad clinical utility based on the nature of the cough reflex is required.

Facial skin cooling induced by a handheld fan alleviates the cough reflex and the urge to cough induced by citric acidhttp://bit.ly/2m1kzAP

Differences between experienced and recalled breathlessness: a review

PURPOSE OF REVIEW

Experienced breathlessness and recalled breathlessness are two different entities, which may be associated with different factors and might have different impacts on function for the individual. The aim was to review the knowledge from the last 2 years concerning experienced breathlessness and recalled breathlessness and related factors.

RECENT FINDINGS

Experienced breathlessness was most often induced or measured during exercise testing in a lab environment using a modified Borg scale. It was associated with both psychological factors, such as social rejection, presence of others, psychosocial stress and prenatal exposure to stress, as well as physical factors, such as hypoxia and frequent exacerbations.Recalled breathlessness was most often measured in epidemiological studies, most commonly using the modified Medical Research Council scale. It was associated with lung volumes, overweight, exercise training, frailty, smoking, personality traits, behavior and marital and occupational status.

SUMMARY

No studies during the review period had directly compared experienced breathlessness and recalled breathlessness. Several factors were related to either experienced breathlessness or recalled breathlessness but no clear differences between factors were found in this review. There is a need for comparative studies using the same measurement methods and in the same settings in order to examine their relation.

Updates in opioid and nonopioid treatment for chronic breathlessness

PURPOSE OF REVIEW

Chronic breathlessness is a troublesome symptom experienced by people with advanced malignant and nonmalignant disease. Disease-directed therapies are often insufficient in the management of chronic breathlessness. Therefore, pharmacological and nonpharmacological breathlessness-specific interventions should be considered for select patients.

RECENT FINDINGS

There is some evidence to support the use of low-dose opioids (≤30 mg morphine equivalents per day) for the relief of breathlessness in the short term. However, additional studies are needed to understand the efficacy of opioids for chronic breathlessness in the long term.Nonopioid therapies, including inspiratory muscle training, fan-to-face therapy, L-menthol and inhaled nebulized furosemide show some promise for the relief of breathlessness in advanced disease. There is insufficient evidence to support the use of anxiolytics and benzodiazepines and cannabis for chronic breathlessness.

SUMMARY

More research is needed to identify therapies for the management of chronic breathlessness.

Fooling the brain to alleviate dyspnoea

Dyspnoea affects a multitude of patients with a multitude of diseases, and therefore concerns a multitude of physicians and other healthcare professionals. In view of the physical and psychological distress associated with dyspnoea, and in view of the pervasive impact of dyspnoea on the patient's psychological state and social life [1, 2], relieving dyspnoea should constitute a leading and universal clinical goal. Some have even proposed that failing to provide a patient with dyspnoea with “state of the art” management of this symptom would constitute an infringement of human rights [3, 4].

The application of a stream of air onto the face by a hand-held fan has a real place in the treatment of dyspnoea http://ow.ly/tKJk30dJ5Pv