Research progress on the pathogenesis of chest tightness variant asthma characterized by chest tightness

Chest tightness variant asthma (CTVA) is an atypical form of asthma with chest tightness as the sole or predominant symptom. The underlying receptors for chest tightness are bronchial C-fibers or rapidly adapting receptors. The nerve impulses are transmitted via the vagus nerve and processed in different regions of the cerebral cortex. Chest tightness is associated with sensory perception, and CTVA patients may have heightened ability to detect subtle changes in lung function, but such sensory perception is unrelated to respiratory muscle activity, lung hyperinflation, or mechanical loading of the respiratory system. Airway inflammation, pulmonary ventilation dysfunction (especially involving small airways), and airway hyperresponsiveness may underlie the sensation of chest tightness. CTVA patients are prone to comorbid anxiety and depression, which share similar central nervous system processing pathways with dyspnea, suggesting a possible neurological basis for the development of CTVA. This article examines the recognition and mechanisms of chest tightness, and explores the pathogenesis of CTVA, focusing on its association with airway inflammation, ventilation dysfunction, airway hyperresponsiveness, and psychosocial factors.

Breath-holding as model for the evaluation of EEG signal during respiratory distress

PURPOSE

Research describes the existence of a relationship between cortical activity and the regulation of bulbar respiratory centers through the evaluation of the electroencephalographic (EEG) signal during respiratory challenges. For example, we found evidences of a reduction in the frequency of the EEG (alpha band) in both divers and non-divers during apnea tests. For instance, this reduction was more prominent in divers due to the greater physiological disturbance resulting from longer apnea time. However, little is known about EEG adaptations during tests of maximal apnea, a test that voluntarily stops breathing and induces dyspnea.

RESULTS

Through this mini-review, we verified that a protocol of successive apneas triggers a significant increase in the maximum apnea time and we hypothesized that successive maximal apnea test could be a powerful model for the study of cortical activity during respiratory distress.

CONCLUSION

Dyspnea is a multifactorial symptom and we believe that performing a successive maximal apnea protocol is possible to understand some factors that determine the sensation of dyspnea through the EEG signal, especially in people not trained in apnea.

Dyspnea and Dyspnea-Associated Anxiety in the ICU Patient Population: A Narrative Review for CL Psychiatrists

BACKGROUND

Consultation-liaison psychiatrists frequently address dyspnea in intensive care unit (ICU) patients. Dyspnea is common in this patient population, but is frequently misunderstood and underappreciated in noncommunicative ICU patients.

OBJECTIVE

This paper provides an updated review on dyspnea specifically in the ICU population, including its pathophysiology and management, pharmacological and nonpharmacological, aimed at consultation-liaison psychiatrists consulting in ICU.

METHODS

A literature review was conducted with PubMed, querying published articles for topics associated with dyspnea and dyspnea-associated anxiety in ICU patient populations. When literature in ICU populations was limited, information was deduced from dyspnea and anxiety management from non-ICU populations. Articles discussing the definition of dyspnea, mechanistic pathways, screening tools, and pharmacologic and nonpharmacologic management were included.

RESULTS

A reference guide was created to help consultation-liaison psychiatrists and intensivists in the screening and treatment of dyspnea and dyspnea-associated anxiety in critically ill patients.

CONCLUSIONS

Dyspnea is frequently associated with anxiety, prolonged days on mechanical ventilation, and worse quality of life after discharge. It can also increase the risk of posttraumatic stress disorder post-ICU discharge. However, it is not routinely screened for, identified, or addressed in the ICU. This manuscript provides an updated review on dyspnea and dyspnea-associated anxietyin the ICU population, including its pathophysiology and management, and offers a useful reference for consultation-liaison psychiatrists to provide treatment recommendations.

Asthma's effect on brain connectivity and cognitive decline

Objective

To investigate the changes in dynamic voxel mirror homotopy connection (dVMHC) between cerebral hemispheres in patients with asthma.

Methods

Our study was designed using a case-control method. A total of 31 subjects with BA and 31 healthy subjects with matching basic information were examined using rsfMRI. We also calculated and obtained the dVMHC value between the cerebral cortexes.

Results

Compared with the normal control group, the dVMHC of the lingual gyrus (Ling) and the calcarine sulcus (CAL), which represented the visual network (VN), increased significantly in the asthma group, while the dVMHC of the medial superior frontal gyrus (MSFG), the anterior/middle/posterior cingulate gyrus (A/M/PCG), and the supplementary motor area (SMA) of the sensorimotor network decreased significantly in the asthma group.

Conclusion

This study showed that the ability of emotion regulation and the efficiency of visual and cognitive information processing in patients with BA was lower than in those in the HC group. The dVMHC analysis can be used to sensitively evaluate oxygen saturation, visual function changes, and attention bias caused by emotional disorders in patients with asthma, as well as to predict airway hyperresponsiveness, inflammatory progression, and dyspnea.

Current pharmacological strategies for symptomatic reduction of persistent breathlessness - a literature review

INTRODUCTION

Persistent breathlessness is a debilitating symptom that is prevalent in the community, particularly in people with chronic and life-limiting illnesses. Treatment includes different steps, including pharmacological treatment aiming to improve the symptom and optimize people's wellbeing.

AREAS COVERED

PubMed and Google Scholar were screened using 'chronic breathlessness' OR 'persistent breathlessness,' AND 'pharmacological treatment,' OR 'opioids.' This review focuses on pharmacological treatments to reduce persistent breathlessness and discusses possible mechanisms involved in the process of breathlessness reduction through pharmacotherapy. Research gaps in the field of persistent breathlessness research are outlined, and future research directions are suggested.

EXPERT OPINION

Regular, low-dose (≤30 mg/day), sustained-release morphine is recommended as the first-line pharmacological treatment for persistent breathlessness. Inter-individual variation in response needs to be investigated in future studies in order to optimize clinical outcomes. This includes 1) better understanding the centrally mediated mechanisms associated with persisting breathlessness and response to pharmacological therapies, 2) understanding benefit from the perspective of people experiencing persistent breathlessness, small and meaningful gains in physical activity.

Laryngology Outcomes Following Implantable Vagus Nerve Stimulation

Importance

Vagus nerve stimulation (VNS) devices have gained widespread acceptance for treatment of resistant epilepsy and depression. The increasing number of procedures has resulted in an increasing number of iatrogenic injuries to the vagus nerve, which can have a significant effect on vocalization and quality of life.

Objective

To determine the relative frequency of laryngeal adverse effects reported to the US Food and Drug Administration (FDA) after VNS implantation and to analyze associated VNS device problems.

Design, Setting, and Participants

This retrospective cross-sectional analysis queried the FDA Manufacturer and User Facility Device Experience database of adverse events in the US between 1996 and 2020.

Main Outcomes and Measures

The primary outcome was the percent of adverse events reported to the FDA that included patients who received VNS with laryngeal adverse effects and the associated proportion of device problems after VNS surgery.

Results

A total of 12 725 iatrogenic vagus nerve issues were documented after VNS implantation, with apnea (n = 395; 3.1%) being the most common patient problem. Overall, 187 reports of laryngeal adverse effects associated with VNS devices were identified and represented the eighth most common iatrogenic vagus nerve problem reported to the FDA. Laryngeal adverse effects included 78 reports of voice alteration and 57 reports of paresis/paralysis. The VNS device problems frequently associated with laryngeal adverse effects were high impedance (n = 15, 8.02%), incorrect frequency delivery (n = 10, 5.35%), and battery problems (n = 11, 5.88%). The number of laryngeal adverse effect reports per year peaked in 2012 with 43 cases.

Conclusions and Relevance

This cross-sectional study found that although the literature demonstrates that vocal changes occur with nearly all VNS devices, the FDA receives adverse event reports of voice changes. Our results emphasize a potential need to improve patient counseling prior to VNS surgery to better set patient expectations regarding vocal changes and to prevent unnecessary patient concern. In addition, reports of vocal fold paresis/paralysis potentially suggest that patients may benefit from preoperative laryngeal assessment to differentiate preexisting vocal fold paralysis from that caused by VNS surgery.

The effect of trait self-control on dyspnoea and tolerance to a CO2 rebreathing challenge in healthy males and females

BACKGROUND

High trait self-control is associated with greater tolerance of unpleasant sensations including effort and pain. Dyspnoea and pain have several commonalities and this study aimed to investigate for the first time whether trait self-control influences responses to a hypercapnic rebreathing challenge designed to induce dyspnoea. As sex also influences tolerance to dyspnoea, we also sought to investigate whether this moderated the role of trait self-control.

METHODS

Participants (n = 65, 32 females) scoring high or low for trait self-control, performed a standardised rebreathing challenge, in which inspired carbon dioxide (CO₂) gradually increased over a period of 6 min or until an intolerable level of dyspnoea. Air hunger (AH) intensity - a distinctive quality of dyspnoea, was measured every 30 s. The multidimensional dyspnoea profile (MDP) was completed after the rebreathing challenge for a more complete overview of breathing discomfort.

RESULTS

Males high in trait self-control (SCHIGH) (302 ± 42 s), tolerated the rebreathing challenge for longer than males low in self-control (SCLOW) (252 ± 66 s, P = 0.021), experienced slower increases in AH intensity during the rebreathing challenge (0.03 ± 0.01 cm^.s ^- 1 vs. 0.04 ± 0.01 cm^.s ^- 1,P = 0.045) and reported lower perceived mental effort on the MDP (4.94 ± 2.46 vs. 7.06 ± 1.60, P = 0.007). There was no difference between SCHIGH and SCLOW females for challenge duration. However, SCHIGH females (9.29 ± 0.66 cm) reported greater air hunger at the end of the challenge than SCLOW females (7.75 ± 1.75 cm, P = 0.003). It is possible that SCLOW females were unwilling to tolerate the same perceptual intensity of AH as the SCHIGH females.

CONCLUSIONS

These results indicate that individuals high in trait self-control are more tolerant of dyspnoea during a CO₂ rebreathing challenge than low self-control individuals. Tolerance of the stimulus was moderated by the sex of the participant, presenting an interesting opportunity for future research.

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).

Acute intermittent hypercapnic-hypoxia elicits central neural respiratory motor plasticity in humans

KEY POINTS

The occurrence of respiratory long-term facilitation following acute exposure to intermittent hypoxia is believed to be dependent upon CO₂ regulation - mechanisms governing the critical role of CO₂ have seldom been explored. We tested the hypothesis that acute intermittent hypercapnic-hypoxia (AIHH) enhances cortico-phrenic neurotransmission in awake healthy humans. The amplitude of diaphragmatic motor-evoked potentials induced by transcranial magnetic stimulation was increased after AIHH, but not the amplitude of compound muscle action potentials evoked by cervical magnetic stimulation. Mouth occlusion pressure (P_0.1 , indicator of neural respiratory drive) was also increased after AIHH, but not tidal volume or minute ventilation. Thus, moderate AIHH elicits central neural mechanisms of respiratory motor plasticity, without measurable ventilatory long-term facilitation in awake humans.

ABSTRACT

Acute intermittent hypoxia (AIH) elicits long-term facilitation (LTF) of respiration. Although LTF is observed when CO₂ is elevated during AIH in awake humans, the influence of CO₂ on corticospinal respiratory motor plasticity is unknown. Thus, we tested the hypotheses that acute intermittent hypercapnic-hypoxia (AIHH): 1) enhances cortico-phrenic neurotransmission (reflecting volitional respiratory control); and 2) elicits ventilatory LTF (reflecting automatic respiratory control). Eighteen healthy adults completed four study visits. Day 1 consisted of anthropometry and pulmonary function testing. On Days 2, 3 and 4, in a balanced alternating sequence, participants received: AIHH, poikilocapnic AIH, and normocapnic-normoxia (Sham). Protocols consisted of 15, 60-s exposures with 90-s normoxic intervals. Transcranial (TMS) and cervical (CMS) magnetic stimulation were used to induce diaphragmatic motor-evoked potentials and compound muscle action potentials, respectively. Respiratory drive was assessed via mouth occlusion pressure (P_0.1 ), and minute ventilation measured at rest. Dependent variables were assessed at baseline and 30-60 min post-exposures. Increases in TMS-evoked diaphragm potential amplitudes were observed following AIHH versus Sham (+28 ± 41%, p = 0.003), but not after AIH. No changes were observed in CMS-evoked diaphragm potential amplitudes. Mouth occlusion pressure also increased after AIHH (+21 ± 34%, p = 0.033), but not after AIH. Ventilatory LTF was not observed after any treatment. We demonstrate that AIHH elicits central neural mechanisms of respiratory motor plasticity and increases resting respiratory drive in awake humans. These findings may have important implications for neurorehabilitation after spinal cord injury and other neuromuscular disorders compromising respiratory motor function. Abstract Figure Legend In a single-blind, cross-over, sham-controlled trial, 18 healthy adults received in a balanced alternating sequence: normocapnic-normoxia (Sham), poikilocapnic acute intermittent hypoxia (AIH), and acute intermittent hypercapnic-hypoxia (AIHH). The study tested the hypothesis that AIHH enhances cortico-phrenic neurotransmission and elicits ventilatory long-term facilitation. Note the increase in the mean amplitude of diaphragmatic motor-evoked potentials (MEP) induced by transcranial magnetic stimulation 60 min after AIHH only, whereas the amplitude of diaphragmatic compound muscle action potentials evoked by cervical (phrenic nerve) stimulation were unchanged after AIHH, AIH and Sham. Traces are composite averages of all participants. Mouth occlusion pressure (P_0.1 ), an indicator of resting respiratory drive, was increased after AIHH, but not after AIH or Sham (see yellow shaded area). Traces are mouth pressure at the onset of an occluded inspiration during resting breathing. Finally, tidal volume (V_T ) was unchanged 30-60 min after AIHH, AIH and Sham. Our results indicate that moderate AIHH elicits a central neural mechanism of respiratory motor plasticity and increases resting respiratory drive in awake humans, without measurable ventilatory long-term facilitation. This article is protected by copyright. All rights reserved.

Cortical Sources of Respiratory Mechanosensation, Laterality, and Emotion: An MEG Study

Airway obstruction activates mechanoreceptors that project to the cerebral cortices in humans, as evidenced by scalp encephalography recordings of cortical neuronal activation, i.e., respiratory-related evoked potential (RREP). However, neural evidence of both high spatial and temporal resolution of occlusion-elicited cortical activation in healthy individuals is lacking. In the present study, we tested our hypothesis that inspiratory mechanical stimuli elicit neural activation in cortical structures that can be recorded using magnetoencephalography (MEG). We further examined the relationship between depression and respiratory symptoms and hemispheric dominance in terms of emotional states. A total of 14 healthy nonsmoking participants completed a respiratory symptom questionnaire and a depression symptom questionnaire, followed by MEG and RREP recordings of inspiratory occlusion. Transient inspiratory occlusion of 300 ms was provided randomly every 2 to 4 breaths, and approximately 80 occlusions were collected in every study participant. Participants were required to press a button for detection when they sensed occlusion. Respiratory-related evoked fields (RREFs) and RREP peaks were identified in terms of latencies and amplitudes in the right and left hemispheres. The Wilcoxon signed-rank test was further used to examine differences in peak amplitudes between the right and left hemispheres. Our results showed that inspiratory occlusion elicited RREF M1 peaks between 80 and 100 ms after triggering. Corresponding neuromagnetic responses peaked in the sensorimotor cortex, insular cortex, lateral frontal cortex, and middle frontal cortex. Overall, the RREF M1 peak amplitude in the right insula was significantly higher than that in the left insula (p = 0.038). The RREP data also showed a trend of higher N1 peak amplitudes in the right hemisphere compared to the left (p = 0.064, one-tailed). Subgroup analysis revealed that the laterality index of sensorimotor cortex activation was significantly different between higher- and lower-depressed individuals (−0.33 vs. −0.02, respectively; p = 0.028). For subjective ratings, a significant relationship was found between an individual’s depression level and their respiratory symptoms (Spearman’s rho = 0.54, p = 0.028, one-tailed). In summary, our results demonstrated that the inspiratory occlusion paradigm is feasible to elicit an RREF M1 peak with MEG. Our imaging results showed that cortical neurons were activated in the sensorimotor, frontal, middle temporal, and insular cortices for the M1 peak. Respiratory occlusion elicited higher cortical neuronal activation in the right insula compared to the left, with a higher tendency for right laterality in the sensorimotor cortex for higher-depressed rather than lower-depressed individuals. Higher levels of depression were associated with higher levels of respiratory symptoms. Future research with a larger sample size is recommended to investigate the role of emotion and laterality in cerebral neural processing of respiratory sensation.

Pathophysiology and Clinical evaluation of the patient with unexplained persistent dyspnea

INTRODUCTION

Dyspnea is a complex symptom, which largely results from an imbalance between an afferent sensory stimulus and the corresponding efferent respiratory neuromuscular response. In addition, it is heavily influenced by the patient's prior experiences and sociocultural factors.

AREAS COVERED

The diagnostic approach to these patients requires a graded, systematic, and often multidisciplinary approach to determine what is the underlying pathophysiologic process. Utilization of objective data obtained through lab testing, imaging, and advanced testing, such as cardiopulmonary exercise testing, is often required to help identify underlying pathology contributing to a patient's symptoms. This article will review dyspnea's underlying pathophysiological mechanisms and standardized approaches to diagnoses. In the expert opinion section, we will discuss our own clinical approach to evaluating patients with persistent dyspnea.

EXPERT OPINION

Unexplained dyspnea is a challenging diagnosis that occurs in patients with and without underlying cardiopulmonary diseases. It requires a systematic approach, which initially uses clinical evaluation in addition to standard imaging and clinical biomarkers. When diagnoses are not made during the initial evaluation, subsequent tests can include cardiopulmonary exercise test and methacholine challenge. To be certain of the correct diagnosis, It is imperative that the clinician determines dyspnea's response to a particular therapeutic intervention.

Associations of symptoms of anxiety and depression with health-status, asthma control, dyspnoea, dysfunction breathing and obesity in people with severe asthma

BACKGROUND

Anxiety and depression are comorbidities of severe asthma. However, clinical characteristics associated with coexisting severe asthma and anxiety/depression are poorly understood. The study objective is to determine clinical characteristics associated with anxiety and depressive symptoms in severe asthma.

METHODS

Severe asthma participants (N = 140) underwent a multidimensional assessment. Categorization of symptoms of anxiety and depression were based on HADS scale sub-scores and divided into four groups (< 8 on both subscales; ≥ 8 on one subscale; ≥ 8 on both subscales). Clinical characteristics were compared between subgroups. Multivariate logistic regression determined associations of clinical characteristics and anxiety and/or depressive symptoms in people with severe asthma.

RESULTS

Participants were (mean ± SD) 59.3 ± 14.7 years old, and 62% female. There were 74 (53%) severe asthma participants without symptoms of anxiety/depression, 11 (7%) with symptoms of anxiety, 37 (26%) with symptoms of depression and 18 (13%) with symptoms of anxiety and depression. Quality of life impairment was greater in participants with symptoms of depression (4.4 ± 1.2) and combined symptoms of anxiety and depression (4.4 ± 1.1). Asthma control was worse in those with symptoms of depression (2.9 ± 1.1) and combined anxiety and depression (2.6 ± 1.0). In multivariate models, dysfunctional breathing was associated with symptoms of anxiety (OR = 1.24 [1.01, 1.53]). Dyspnoea was associated with symptoms of depression (OR = 1.90 [1.10, 3.25]). Dysfunctional breathing (OR 1.16 [1.04, 1.23]) and obesity (OR 1.17 [1.00, 1.35]) were associated with combined symptoms of anxiety and depression.

CONCLUSION

People with severe asthma and anxiety and/or depressive symptoms have poorer QoL and asthma control. Dyspnoea, dysfunctional breathing and obesity are associated with these symptoms. These key clinical characteristics should be targeted in severe asthma management.

Randomised controlled trial to investigate the use of high-frequency airway oscillations as raining to mprove yspnoa (TIDe) in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by symptomatic dyspnoea and reduced exercise tolerance, in part as a result muscle weakness, for which inspiratory muscle training (IMT) may be useful. Excess mucus hypersecretion commonly coexists in COPD and may lead to reduce ventilation, further impacting on breathlessness. Devices for sputum clearance may be employed to aid mucus expectoration. This trial aimed to explore the effectiveness of a combined IMT and high-frequency airway oscillating (HFAO) device in the management of dyspnoea.

METHODS

This was a double-blinded, randomised sham-controlled trial which recruited symptomatic patients with COPD. Patients were randomised to either a HFAO device (Aerosure) or sham device for 8 weeks, three times a day. The primary outcome was the Chronic Respiratory Questionnaire dyspnoea (CRQ-D) domain. Pre-specified subgroup analyses were performed including those with respiratory muscle weakness, excessive sputum and frequent exacerbators.

RESULTS

104 participants (68% men, mean (SD) age 69.75 years (7.41), forced expiratory volume in 1 s per cent predicted 48.22% (18.75)) were recruited to this study with 96 participants completing. No difference in CRQ-D was seen between groups (0·28, 95% CI -0.19 to 0.75, p=0.24), though meaningful improvements were seen over time in both groups (mean (SD) HFAO 0.45 (0.78), p<0.01; sham 0.73 (1.09), p<0.01). Maximal inspiratory pressure significantly improved in the HFAO group over sham (5.26, 95% CI 0.34 to 10.19, p=0.05). Similar patterns were seen in the subgroup analysis.

CONCLUSION

There were no statistical differences between the HFAO and the sham group in improving dyspnoea measured by the CRQ-D.

TRIAL REGISTRATION NUMBER

ISRCTN45695543.

Silent hypoxaemia in COVID-19 patients

The clinical presentation of COVID-19 due to infection with SARS-CoV-2 is highly variable with the majority of patients having mild symptoms while others develop severe respiratory failure. The reason for this variability is unclear but is in critical need of investigation. Some COVID-19 patients have been labelled with 'happy hypoxia', in which patient complaints of dyspnoea and observable signs of respiratory distress are reported to be absent. Based on ongoing debate, we highlight key respiratory and neurological components that could underlie variation in the presentation of silent hypoxaemia and define priorities for subsequent investigation.

Rationale for targeted self-management strategies for breathlessness in heart failure

To provide a conceptual rationale for targeted self-management strategies for breathlessness in chronic heart failure. Breathlessness is a defining symptom of chronic heart failure and is the primary cause for hospital readmissions and emergency room visits, resulting in extensive health care utilization. Chronic breathlessness, punctuated by acute physiological decompensation, is a sentinel symptom of the heart failure syndrome and often intensifies towards the end of life. Drawing upon evidence-based guidelines, physiological mechanisms and existing conceptual models for the management of breathlessness is proposed. Key elements of this model include adherence to evidence-based approaches (pharmacological and non-pharmacological management to optimize heart failure treatment), self-monitoring of symptoms, identification of modifiable factors (such as fluid overload), and targeted strategies for breathlessness including distraction and gas flow. Self-management is an essential component in heart failure management which could positively influences health outcomes and quality of life. Refining programs to focus on breathlessness may have the potential to reduce symptom burden and improve quality of life.

Oral morphine drops for prompt relief of breathlessness in patients with advanced cancer-a randomized, double blinded, crossover trial of morphine sulfate oral drops vs. morphine hydrochloride drops with ethanol (red morphine drops)

PURPOSE

Episodic breathlessness is frequent in palliative cancer patients. Opioids are the only pharmacological agents with sufficient evidence in treatment. In Denmark, the main recommendation is red morphine drops (RMD), an off-label solution of morphine, ethanol, and red color (cochenille) described since 1893 (Pharmacopoea Danica). In 2015, the Danish Medicines Agency increased focus on off-label medicines and recommended registered morphine drops without ethanol instead. However, our palliative patients told us that RMD was better. For that reason, we conducted a clinical trial to clarify any perceived difference between the two types of drops.

METHODS

We conducted a randomized, double blinded, crossover trial. Patients were asked to perform standardized activity (2-min walk) aiming to provoke breathlessness. Primary endpoint (breathlessness NRS) and secondary endpoints (saturation, pulse, respiratory frequency) were measured before (t = 0) and after test medicine at t = 1, t = 3, t = 5, t = 10, and t = 20 min. After 2-4 days (washout period), the patients repeated the test, receiving the alternative drops in a blinded setup (crossover).

RESULTS

In the first 3 min, the relative drop in breathlessness for morphine drops with ethanol (RMD) was significant more than for morphine drops without ethanol. We found no significant difference in secondary endpoints.

CONCLUSIONS

A conclusion could be that ethanol might facilitate morphine absorption in the mouth. Our results needs further research of opioid absorption in the mouth as well as trials, testing morphine vs. more lipophilic opioids. The RMD drops are cheap, easy to use, and noninvasive and keep the patient independent of health care professionals.

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.

Activity-related dyspnea in chronic obstructive pulmonary disease: physical and psychological consequences, unmet needs, and future directions

Dyspnea is a distressing, debilitating, and near-ubiquitous symptom affecting patients with COPD. In addition to the functional consequences of dyspnea, which include activity limitation and reduced exercise tolerance, it is important to consider its psychological impact on patients with COPD, such as onset of depression or anxiety. Moreover, the anticipation of dyspnea itself can have a significant effect on patients' emotions and behavior, with patients frequently self-limiting physical activity to avoid what has become the hallmark symptom of COPD. Dyspnea is, therefore, a key target for COPD treatments. Pharmacologic treatments can optimize respiratory mechanics, provide symptom relief, and reduce patients' increased inspiratory neural drive to breathe. However, it is important to acknowledge the value of non-pharmacologic interventions, such as pulmonary rehabilitation and patient self-management education, which have proven to be invaluable tools for targeting the affective components of dyspnea. Furthermore, it is important to encourage maintenance of physical activity to optimize long-term patient outcomes. Here, we review the physiological and psychological consequences of activity-related dyspnea in COPD, assess the efficacy of modern management strategies in improving this common respiratory symptom, and discuss key unmet clinical and research needs that warrant further immediate attention.

The Effect of 20-Minute Mindful Breathing on the Rapid Reduction of Dyspnea at Rest in Patients With Lung Diseases: A Randomized Controlled Trial

CONTEXT

Dyspnea is a common and distressing symptom in respiratory diseases. Despite advances in the treatment of various lung diseases, the treatment modalities for dyspnea remain limited.

OBJECTIVES

This study aims to examine the effect of 20-minute mindful breathing on the rapid reduction of dyspnea at rest in patients with lung cancer, chronic obstructive pulmonary disease, and asthma.

METHODS

We conducted a parallel-group, nonblinded, randomized controlled trial of standard care plus 20-minute mindful breathing vs. standard care alone for patients with moderate to severe dyspnea due to lung disease, named previously, at the respiratory unit of University Malaya Medical Centre in Malaysia, from August 1, 2017, to March 31, 2018.

RESULTS

Sixty-three participants were randomly assigned to standard care plus a 20-minute mindful breathing session (n = 32) or standard care alone (n = 31), with no difference in their demographic and clinical characteristics. There was statistically significant reduction in dyspnea in the mindful breathing group compared with the control group at minute 5 (U = 233.5, n₁ = 32, n₂ = 31, mean rank₁ = 23.28, mean rank₂ = 37.72, z = -3.574, P < 0.001) and minute 20 (U = 232.0, n₁ = 32, n₂ = 31, mean rank₁ = 23.00, mean rank₂ = 36.77, z = -3.285, P = 0.001).

CONCLUSION

Our results provide evidence that a single session of 20-minute mindful breathing is effective in reducing dyspnea rapidly for patients with lung cancer, chronic obstructive pulmonary disease, and asthma.

Inhaled furosemide for relief of air hunger versus sense of breathing effort: a randomized controlled trial

Background

Inhaled furosemide offers a potentially novel treatment for dyspnoea, which may reflect modulation of pulmonary stretch receptor feedback to the brain. Specificity of relief is unclear because different neural pathways may account for different components of clinical dyspnoea. Our objective was to evaluate if inhaled furosemide relieves the air hunger component (uncomfortable urge to breathe) but not the sense of breathing work/effort of dyspnoea.

Methods

A randomised, double blind, placebo-controlled crossover trial in 16 healthy volunteers studied in a university research laboratory. Each participant received 3 mist inhalations (either 40 mg furosemide or 4 ml saline) separated by 30–60 min on 2 test days. Each participant was randomised to mist order ‘furosemide-saline-furosemide’ (n- = 8) or ‘saline-furosemide-saline’ (n = 8) on both days. One day involved hypercapnic air hunger tests (mean ± SD PCO₂ = 50 ± 3.7 mmHg; constrained ventilation = 9 ± 1.5 L/min), the other involved work/effort tests with targeted ventilation (17 ± 3.1 L/min) and external resistive load (20cmH₂O/L/s). Primary outcome was ratings of air hunger or work/effort every 15 s on a visual analogue scale. During saline inhalations, 1.5 mg furosemide was infused intravenously to match the expected systemic absorption from the lungs when furosemide is inhaled. Corresponding infusions of saline during furosemide inhalations maintained procedural blinding. Average visual analogue scale ratings (%full scale) during the last minute of air hunger or work/effort stimuli were analysed using Linear Mixed Methods.

Results

Data from all 16 participants were analysed. Inhaled furosemide relative to inhaled saline significantly improved visual analogues scale ratings of air hunger (Least Squares Mean ± SE − 9.7 ± 2%; p = 0.0015) but not work/effort (+ 1.6 ± 2%; p = 0.903). There were no significant adverse events.

Conclusions

Inhaled furosemide was effective at relieving laboratory induced air hunger but not work/effort in healthy adults; this is consistent with the notion that modulation of pulmonary stretch receptor feedback by inhaled furosemide leads to dyspnoea relief that is specific to air hunger, the most unpleasant quality of dyspnoea.

Funding

Oxford Brookes University Central Research Fund.

Trial registration

ClinicalTrials.gov Identifier: NCT02881866. Retrospectively registered on 29th August 2018.

Abnormal Functional Connectivity of Ventral Anterior Insula in Asthmatic Patients with Depression

Objective

To explore the underlying mechanism of depression in asthmatic patients, the ReHo in the insula and its FC was used to probe the differences between depressed asthmatic (DA) and nondepressed asthmatic (NDA) patients.

Methods

18 DA patients, 24 NDA patients, and 60 healthy controls (HCs) received resting-state fMRI scan, severity of depression, and asthma control assessment.

Results

DA patients showed increased FC between the left ventral anterior insula (vAI) and the left middle temporal gyrus compared with both NDA and HC groups. In addition, compared with HCs, the DA and NDA patients both exhibited increased FC between the left vAI and the right anterior cingulate cortex (ACC), decreased FC between the left vAI and the bilateral parietal lobe, and increased FC between the right vAI and the left putamen and the right caudate, respectively. Furthermore, the increased FC between the left vAI and the right ACC could differentiate HCs from both DA and NDA patients, and the increased FC between the right vAI and both the left putamen and the right caudate could separate NDA patients from HCs.

Conclusions

This study confirmed that abnormal vAI FC may be involved in the neuropathology of depression in asthma. The increased FC between the left vAI and the left MTG could distinguish DA from the NDA and HC groups.

When dyspnea gets worse: Suffocation fear and the dynamics of defensive respiratory responses to increasing interoceptive threat

In patients with anxiety and/or respiratory diseases, body sensations, particularly from the respiratory system, may increase in intensity and aversiveness and thus lead into defensive action (e.g., escape) or panic. The processes, however, that might contribute to the culmination of symptoms and the switch into defensive action have not been well understood yet. The current study aimed at evaluating an experimental paradigm to characterize the dynamics of defensive mobilization to body sensations increasing in intensity and aversiveness. Persons reporting low and high suffocation fear (SF; N = 69) were exposed to increasingly unpleasant feelings of dyspnea induced by inspiratory resistive loads and a breathing occlusion requiring voluntary breath holding. Respiratory responses were assessed along with subjective reports of anxiety and panic symptoms. Presentation of respiratory loads with increasing physical resistance led to increasingly unpleasant feelings of dyspnea. Twenty-eight participants terminated the exposure prematurely at least once. When dyspnea was severe, high compared to low SF persons exhibited an increased respiratory rate that was accompanied by reports of more intense panic symptoms. Premature terminations of exposure were preceded by a surge in anxiety, breathing frequency, and mouth pressure, and a decrease in tidal volume. We successfully established an experimental paradigm to assess changes in defensive responding with increasing intensity of an interoceptive threat. The current data foster our understanding of behavioral expression patterns observed in patients with anxiety and/or respiratory diseases and the processes involved in the culmination of bodily sensations and anxiety into panic.

Group Cognitive Behavior Therapy Reversed Insula Subregions Functional Connectivity in Asthmatic Patients

Background: Group cognitive behavior therapy (GCBT) is an effective treatment in improving self-management behaviors and quality of life for asthmatic patients. However, the mechanisms by which GCBT improves asthma-related clinical symptoms remain unknown. Previous studies have indicated that insula is an important region involved in the neuropathology of asthma. Therefore, we examined the possible alteration of functional connectivity (FC) in insula subregions after GCBT in asthmatic patients. Methods: Forty-two asthmatic patients and 60 healthy controls (HCs) received resting-state functional magnetic resonance imaging (rs-fMRI) scan and clinical assessments, 17 asthmatic patients completed GCBT treatment consisting of 8 sessions, and then received rs-fMRI scan and clinical assessments. Results: Asthmatic patients had greater left ventral anterior insula (vAI) FC with the left cerebellum posterior lobe, right middle temporal gyrus, and bilateral anterior cingulate cortex (ACC), but less FC with bilateral postcentral gyrus, bilateral occipital lobe, and left precentral gyrus compared with HCs. FC between left posterior insula and left medial frontal gyrus also increased in the patients. In addition, right vAI showed increased FC with right caudate and left putamen. FC between right dorsal anterior insula (dAI) and left calcarine however decreased. The increase in FC in insula subregions were significantly improved following GCBT. FC between the left vAI connectivity and left postcentral gyrus was positively correlated with the percentage of improvement in 17-items Hamilton depression rating scale scores, and FC between the right dAI and left calcarine was negatively associated with the improvement percentage in asthma control test scores. Conclusions: This study in the first time demonstrated that GCBT led to significant improvement of FC between insula subregions and other brain regions. Clinical Trial Registration: An investigation of therapeutic mechanism in asthmatic patients: based on the results of Group Cognitive Behavioral Therapy (Registration number: ChiCTR-COC-15007442) (http://www.chictr.org.cn/usercenter.aspx).

Coupling of dyspnea perception and occurrence of tachypnea during exercise

During exercise, tidal volume initially contributes to ventilatory responses more than respiratory frequency, and respiratory frequency then increases rapidly while tidal volume stabilizes. Dyspnea intensity is also known to increase in a threshold-like manner. We tested the possibility that the threshold of tachypneic breathing is equal to that of dyspnea perception during cycle ergometer exercise (n = 27). Dyspnea intensity was scored by a visual analog scale. Thresholds were expressed as values of pulmonary O2 uptake at each breakpoint. Dyspnea intensity and respiratory frequency started increasing rapidly once the intensity of stimuli exceeded a threshold level. The thresholds for dyspnea intensity and for occurrence of tachypnea were significantly correlated. An intraclass correlation coefficient of 0.71 and narrow limits of agreement on the Bland-Altman plot indicated a good agreement between these thresholds. These results suggest that the start of tachypneic breathing coincides with the threshold for dyspnea intensity during cycle ergometer exercise.

[Pulmonary causes of chest pain]

Chest pain represents one of the most frequent symptoms of pulmonary diseases, in addition to dyspnea and cough. The broad differential diagnostics include the intensely painful but prognostically benign acute pleurisy as well as potentially life-threatening events, such as acute pulmonary embolism or malignant chest diseases. Primary spontaneous pneumothorax is characterized by acute chest pain. Pain associated with a respiratory infection, such as pneumonia rarely poses a difficult diagnostic problem. Painful diseases of the lungs can be differentiated in an initial approach by asking the patient if the pain is related to breathing, which is characteristic of pleuritic chest diseases. Pulmonary hypertension, lung cancer and mesothelioma show more constant pain unrelated to respiratory movements. It is most important to differentiate pain associated with acute exacerbation of chronic obstructive pulmonary disease (COPD), whereby a possible cardiac comorbidity, such as acute coronary syndrome (ACS) should always be considered.

Tension pneumothorax recurrence in COPD: a care study

This care study concerns a patient with chronic obstructive pulmonary disease, who endures the recurrence of a tension pneumothorax. A holistic and evidence-based approach is employed to critically discuss his assessment, pathophysiology, and nursing care. These discussions facilitate extrapolation of implications pertinent to nursing practice.

Opioids for the palliation of refractory breathlessness in adults with advanced disease and terminal illness

BACKGROUND

Breathlessness is a common and disabling symptom which affects many people with advanced cardiorespiratory disease and cancer. The most effective treatments are aimed at treating the underlying disease. However, this may not always be possible, and symptomatic treatment is often required in addition to maximal disease-directed therapy. Opioids are increasingly being used to treat breathlessness, although their mechanism of action is still not completely known. A few good sized, high quality trials have been conducted in this area.

OBJECTIVES

To determine the effectiveness of opioid drugs in relieving the symptom of breathlessness in people with advanced disease due to malignancy, respiratory or cardiovascular disease, or receiving palliative care for any other disease.

SEARCH METHODS

We performed searches on CENTRAL, MEDLINE, EMBASE, CINAHL, and Web of Science up to 19 October 2015. We handsearched review articles, clinical trial registries, and reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised double-blind controlled trials that compared the use of any opioid drug against placebo or any other intervention for the relief of breathlessness. The intervention was any opioid, given by any route, in any dose.

DATA COLLECTION AND ANALYSIS

We imported studies identified by the search into a reference manager database. We retrieved the full-text version of relevant studies, and two review authors independently extracted data. The primary outcome measure was breathlessness and secondary outcome measures included exercise tolerance, oxygen saturations, adverse events, and mortality. We analysed all studies together and also performed subgroup analyses, by route of administration, type of opioid administered, and cause of breathlessness. Where appropriate, we performed meta-analysis. We assessed the evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach and created three 'Summary of findings' tables.

MAIN RESULTS

We included 26 studies with 526 participants. We assessed the studies as being at high or unclear risk of bias overall. We only included randomised controlled trials (RCTs), although the description of randomisation was incomplete in some included studies. We aimed to include double blind RCTs, but two studies were only single blinded. There was inconsistency in the reporting of outcome measures. We analysed the data using a fixed-effect model, and for some outcomes heterogeneity was high. There was a risk of imprecise results due to the low numbers of participants in the included studies. For these reasons we downgraded the quality of the evidence from high to either low or very low.For the primary outcome of breathlessness, the mean change from baseline dyspnoea score was 0.09 points better in the opioids group compared to the placebo group (ranging from a 0.36 point reduction to a 0.19 point increase) (seven RCTs, 117 participants, very low quality evidence). A lower score indicates an improvement in breathlessness. The mean post-treatment dyspnoea score was 0.28 points better in the opioid group compared to the placebo group (ranging from a 0.5 point reduction to a 0.05 point increase) (11 RCTs, 159 participants, low quality evidence).The evidence for the six-minute walk test (6MWT) was conflicting. The total distance in 6MWT was 28 metres (m) better in the opioids group compared to placebo (ranging from 113 m to 58 m) (one RCT, 11 participants, very low quality evidence). However, the change in baseline was 48 m worse in the opioids group (ranging from 36 m to 60 m) (two RCTs, 26 participants, very low quality evidence).The adverse effects reported included drowsiness, nausea and vomiting, and constipation. In those studies, participants were 4.73 times more likely to experience nausea and vomiting compared to placebo, three times more likely to experience constipation, and 2.86 times more likely to experience drowsiness (nine studies, 162 participants, very low quality evidence).Only four studies assessed quality of life, and none demonstrated any significant change.

AUTHORS' CONCLUSIONS

There is some low quality evidence that shows benefit for the use of oral or parenteral opioids to palliate breathlessness, although the number of included participants was small. We found no evidence to support the use of nebulised opioids. Further research with larger numbers of participants, using standardised protocols and with quality of life measures included, is needed.

Exertional dyspnoea and cortical oxygenation in patients with COPD

This study was designed to investigate the association of perceived dyspnoea intensity with cortical oxygenation and cortical activation during exercise in patients with chronic obstructive pulmonary disease (COPD) and exertional hypoxaemia.Low-intensity exercise was performed at a constant work rate by patients with COPD and exertional hypoxaemia (n=11) or no hypoxaemia (n=16), and in control participants (n=11). Cortical oxyhaemoglobin (oxy-Hb) and deoxyhaemoglobin (deoxy-Hb) concentrations were measured by multichannel near-infrared spectroscopy. Increased deoxy-Hb is assumed to reflect impaired oxygenation, whereas decreased deoxy-Hb signifies cortical activation.Exercise decreased cortical deoxy-Hb in control and nonhypoxaemic patients. Deoxy-Hb was increased in hypoxaemic patients and oxygen supplementation improved cortical oxygenation. Decreased deoxy-Hb in the pre-motor cortex (PMA) was significantly correlated with exertional dyspnoea in control participants and patients with COPD without hypoxaemia. In contrast, increased cortical deoxy-Hb concentration was correlated with dyspnoea in patients with COPD and hypoxaemia. With the administration of oxygen supplementation, exertional dyspnoea was correlated with decreased deoxy-Hb in the PMA of COPD patients with hypoxaemia.During exercise, cortical oxygenation was impaired in patients with COPD and hypoxaemia compared with control and nonhypoxaemic patients; this difference was ameliorated with oxygen supplementation. Exertional dyspnoea was related to activation of the pre-motor cortex in COPD patients.

The impact of exercise-induced bronchoconstriction on athletic performance: a systematic review

BACKGROUND

Exercise-induced bronchoconstriction (EIB) describes the phenomenon of transient airway narrowing in association with physical activity. Although it may seem likely that EIB would have a detrimental impact on athletic performance, this has yet to be established.

OBJECTIVES

The aim of this review is to provide a systematic appraisal of the current status of knowledge regarding EIB and exercise performance and to highlight potential mechanisms by which performance may be compromised by EIB.

DATA SOURCES AND STUDY SELECTION

PubMed/Medline and EBSCO databases were searched up to May 2014 using the search parameter: [('exercise' OR 'athlete') AND ('asthma' OR 'bronchoconstriction' OR 'hypersensitivity') AND 'performance']. This search string returned 243 citations. After systematically reviewing all of the abstracts, 101 duplicate papers were removed, with 132 papers excluded for not including an exercise performance outcome measure.

RESULTS

The remaining ten studies that met the initial criteria were included in this review; six evaluated the performance of physically active individuals with asthma and/or EIB while four assessed the effects of medication on performance in a comparable population.

CONCLUSION

The evidence concludes that whilst it is reasonable to suspect that EIB does impact athletic performance, there is currently insufficient evidence to provide a definitive answer.

Diagnosis of asthma - new theories

INTRODUCTION

Recent studies have shown a remarkably high frequency of poorly controlled asthma. Several reasons for this treatment failure have been discussed, however, the basic question of whether the diagnosis is always correct has not been considered. Follow-up studies have shown that in many patients asthma cannot be verified despite ongoing symptoms. Mechanisms other than bronchial obstruction may therefore be responsible. The current definition of asthma may also include symptoms that are related to mechanisms other than bronchial obstruction, the clinical hallmark of asthma.

AIM

Based on a review of the four cornerstones of asthma - inflammation, hyperresponsiveness, bronchial obstruction and symptoms - the aim was to present some new aspects and suggestions related to the diagnosis of adult non-allergic asthma.

CONCLUSION

Recent studies have indicated that "classic" asthma may sometimes be confused with asthma-like disorders such as airway sensory hyperreactivity, small airways disease, dysfunctional breathing, non-obstructive dyspnea, hyperventilation and vocal cord dysfunction. This confusion may be one explanation for the high proportion of misdiagnosis and treatment failure. The current diagnosis, focusing on bronchial obstruction, may be too "narrow". As there may be common mechanisms a broadening to include also non-obstructive disorders, forming an asthma syndrome, is suggested. Such broadening requires additional diagnostic steps, such as qualitative studies with analysis of reported symptoms, non-effort demanding methods for determining lung function, capsaicin test for revealing airway sensory hyperreactivity, careful evaluation of the therapeutic as well as diagnostic effect of corticosteroids and testing of suggested theories.

The Challenge of Diagnosing Dyspnea

Dyspnea is a subjective and nonspecific symptom, yet very distressing for those who experience it. Acute onset dyspnea and exacerbation of chronic dyspnea from heart or lung disease significantly add to the number of emergency department visits and inpatient admissions. Although dyspnea may appear to be a simple condition to evaluate and manage, it is actually complex in description and quality. As such, dyspnea is the first symptom of many diseases. The onset of dyspnea can be due to a new acute disease, the exacerbation of an existing chronic illness, or a new disease compounding a chronic illness. Finding the cause of dyspnea is generally more difficult than it originally may appear. Therefore, the purpose of this article is to discuss the differential diagnoses associated with dyspnea.

Error signals as powerful stimuli for the operant conditioning-like process of the fictive respiratory output in a brainstem-spinal cord preparation from rats

Respiratory neuromuscular activity needs to adapt to physiologic and pathologic conditions. We studied the conditioning effects of sensory fiber (putative Ia and II type from neuromuscular spindles) stimulation on the fictive respiratory output to the diaphragm, recorded from C4 phrenic ventral root, of in-vitro brainstem-spinal cord preparations from rats. The respiratory burst frequency in these preparations decreased gradually (from 0.26±0.02 to 0.09±0.003 bursts(-1)±SEM) as the age of the donor rats increased from zero to 4 days. The frequency greatly increased when the pH of the bath was lowered, and was significantly reduced by amiloride. C4 low threshold, sensory fiber stimulation, mimicking a stretched muscle, induced a short-term facilitation of the phrenic output increasing burst amplitude and frequency. When the same stimulus was applied contingently on the motor bursts, in an operant conditioning paradigm (a 500ms pulse train with a delay of 700ms from the beginning of the burst) a strong and persistent (>1h) increase in burst frequency was observed (from 0.10±0.007 to 0.20±0.018 bursts(-1)). Conversely, with random stimulation burst frequency increased only slightly and declined again within minutes to control levels after stopping stimulation. A forward model is assumed to interpret the data, and the notion of error signal, i.e. the sensory fiber activation indicating an unexpected stretched muscle, is re-considered in terms of the reward/punishment value. The signal, gaining hedonic value, is reviewed as a powerful unconditioned stimulus suitable in establishing a long-term operant conditioning-like process.

Increased respiratory drive relates to severity of dyspnea in systemic sclerosis

BACKGROUND

Dyspnea may be a presenting symptom in progressive systemic sclerosis (SSc). Respiratory drive (mouth occlusion pressure, MOP, at rest and during CO2 rebreathing, 7% CO2, 93% O2) is a major determinant of dyspnea and may relate to the magnitude of dyspnea.

METHODS

In a prospective design, MOP at 0.1 sec (P0.1) was measured in 73 SSc patients while breathing room air and during CO2 rebreathing. An abnormal V'E/P0.1 is defined as < 8 L/min/cm H2O. Dyspnea scores were assessed by a shortness of breath questionnaire (UCSD dyspnea scale).

RESULTS

Mean P0.1 in patients with normal V'E/P0.1 (n = 45) was 1.1 ± 0.04 and 1.6 ± 0.08 cm H2O in patients with abnormal V'E/P0.1 (n = 28), p <0.001. ∆P0.1/∆PetCO2 differed significantly between these groups (0.45 versus 0.75 cm H2O/mmHg, P < 0.001), but no significant difference was present in ∆V'E/∆PetCO2. V'E/P0.1 showed the highest significant correlation with the UCSD dyspnea score (r = -0.76, p <0.001). UCSD cut-off value for abnormal V'E/P0.1 was 8.5 (sensitivity 93%, specificity 96%, area under the curve 0.98).

CONCLUSIONS

In SSc patients an abnormal V'E/P0.1 better relates to the severity of dyspnea than traditional lung function parameters and can easily be assessed at first outpatient consultation.

Voice-related modulation of mechanosensory detection thresholds in the human larynx

Rapidly adapting mechanoreceptors within the laryngeal mucosa provide the central nervous system with perceptual and proprioceptive afference for a variety of essential yet diverse human functions including voice sound production and airway protection. It is unknown why mechanosensory information that yields a defensive response when an individual breathes may go largely unnoticed when the individual voices. Therefore, a central question is whether there is voice-related modulation of laryngeal mechanosensory detection. Such modulation would be consistent with current models of afferent laryngeal control, and may be important to maintain fluent voice in the presence of potentially distracting sensory input. Therefore, we employed endoscopic assessment of laryngeal mechanosensory detection thresholds in ten healthy adults during tidal breathing and a voice task. We tested the hypothesis that laryngeal mechanosensory detection thresholds would be higher during the voice task. We found that thresholds were significantly higher for all participants during the voice task and that these changes were significantly more modest in women. Our findings suggest that the laryngeal sensorium may modulate mechanosensory afference to attenuate the potentially distracting influence of sensory input during voice. The finding that women maintain a greater sensitivity during the voice task than men (lower thresholds) may have important implications for the higher prevalence of sensorimotor voice disturbances in women. Our results are consistent with the presence of mechanosensory modulation in other motor systems and with observed sensory differences between women and men. Such modulation has important implications for understanding the underlying neural mechanisms of laryngeal control and how these mechanisms may operate in individuals with laryngeal disturbances.

Mechanisms of acute exacerbation of respiratory symptoms in chronic obstructive pulmonary disease

Exacerbations of chronic obstructive respiratory disease (ECOPD) are acute events characterized by worsening of the patient's respiratory symptoms, particularly dyspnoea, leading to change in medical treatment and/or hospitalisation. AECOP are considered respiratory diseases, with reference to the respiratory nature of symptoms and to the involvement of airways and lung. Indeed respiratory infections and/or air pollution are the main causes of ECOPD. They cause an acute inflammation of the airways and the lung on top of the chronic inflammation that is associated with COPD. This acute inflammation is responsible of the development of acute respiratory symptoms (in these cases the term ECOPD is appropriate). However, the acute inflammation caused by infections/pollutants is almost associated with systemic inflammation, that may cause acute respiratory symptoms through decompensation of concomitant chronic diseases (eg acute heart failure, thromboembolism, etc) almost invariably associated with COPD. Most concomitant chronic diseases share with COPD not only the underlying chronic inflammation of the target organs (i.e. lungs, myocardium, vessels, adipose tissue), but also clinical manifestations like fatigue and dyspnoea. For this reason, in patients with multi-morbidity (eg COPD with chronic heart failure and hypertension, etc), the exacerbation of respiratory symptoms may be particularly difficult to investigate, as it may be caused by exacerbation of COPD and/or ≥ comorbidity, (e.g. decompensated heart failure, arrhythmias, thromboembolisms) without necessarily involving the airways and lung. In these cases the term ECOPD is inappropriate and misleading.

When the chief complaint is (or should be) dyspnea in adults

Dyspnea, "a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity," is an important and challenging complaint associated with a wide variety of adverse clinical outcomes, including hospitalizations for chronic obstructive pulmonary disease and cardiac mortality. Although up to 85% of cases are caused by asthma, chronic obstructive pulmonary disease, interstitial lung disease, pneumonia, cardiac ischemia, congestive heart failure, or psychogenic disorders, a systematic approach can help to identity uncommon, but important, causes of dyspnea. In this review that includes clinical examples as well as a didactic review of currently available information, we suggest a step-wise approach to the evaluation of the adult patient with dyspnea. It is also important to avoid 3 possible pitfalls: accepting a cause for dyspnea in which the element identified is only part of a syndrome which includes that element; accepting a single cause for dyspnea when the cause is multifactorial; and failing to recognize a diagnosis and cause of dyspnea is incorrect and has been assumed without rigorous confirmation, when a patient with a specific diagnosis is referred for "failing to respond to treatment."

Lung/chest expansion contributes to generation of pleasantness associated with dyspnoea relief

Pleasantness associated with dyspnoea relief or 'respiratory pleasure' is considered as a particular sensory experience. The purpose of this study is to elucidate the mechanism of generation of this particular sensory experience. After taking deep breaths during normal breathing, 35 healthy subjects received three different magnitudes of inspiratory loads (light: 8.4; moderate: 23.4; severe: 70.5 cm H2O/L/s) to induce dyspnoeic sensation. We found that (1) deep breaths during normal breathing rarely induce 'respiratory pleasure', (2) a sudden removal of dyspnoea alone is not sufficient to produce 'respiratory pleasure', and (3) the generation of 'respiratory pleasure' can be observed when a sudden removal of dyspnoea accompanies a large increase in tidal volume (V(T)). In addition, qualitative assessment of 'respiratory pleasure' showed that this sensation is compatible with a strong, positively valenced sensation. These findings indicate that an increase in V(T) after removal of respiratory loading plays a crucial role in generation of 'respiratory pleasure' that is a specific sensory-emotional experience.

Exercise therapy in the management of dyspnea in patients with cancer

PURPOSE OF REVIEW

Dyspnea is a frequent, debilitating, and understudied symptom in cancer associated with poor prognosis and reduced health-related quality of life. The purpose of this study is to review the incidence, pathophysiology, and mechanisms of dyspnea in patients diagnosed with cancer. We also discuss the existing evidence supporting the efficacy of exercise therapy to complement traditional approaches to reduce the impact of this devastating symptom in persons with cancer.

RECENT FINDINGS

In other clinical populations presenting with dyspnea, such as chronic obstructive pulmonary disease, exercise therapy is demonstrated to be an efficacious strategy. In contrast, relatively few studies to date have investigated the efficacy of exercise training as a therapeutic strategy to mitigate dyspnea in patients with cancer.

SUMMARY

Although much more work is required, exercise therapy is a promising adjunct strategy to systematically reduce dyspnea in the oncology setting that may also provide additive efficacy when prescribed in combination with other adjunct therapies including pharmacologic interventions.

Diagnosis of asthma - a new approach

Current definition of asthma involves four cornerstones: inflammation, hyperresponsiveness, bronchoconstriction, and symptoms. In research, the symptoms have had the slightest attention. According to international guidelines, the asthma symptoms are episodic breathlessness, wheeze, cough, tightness of the chest, and shortness of breath. As there are several symptoms, a primary question is how they are related to bronchoconstriction, the main clinical feature of asthma. Symptoms and lung function tests are regularly used for the evaluation of clinical health status and effect of treatment. However, there is no or poor correlation between these two variables, which means that they represent different mechanisms. Reduced lung function, such as a low FEV(1) , represents bronchial constriction, what do the symptoms represent? Some symptoms such as breathlessness and shortness of breath seem not to be evidence-based asthma symptoms. Focusing on bronchial obstruction is important in view of the potential risk of asthma attacks, but nonobstructive symptoms occur frequently and may also cause severe discomfort and poor quality of life. Interpreting all symptoms as signs of bronchoconstriction (asthma) may lead to misinterpretation when assessing health status and effect of treatment. Although a 'soft' variable, the strength of symptoms is that they are representing various mechanisms. The physiological preconditions for control and defense of respiration must be considered in the diagnostic process, regardless of inflammation, allergy, psychology, or other etiological factors. Based on studies on dyspnea in cardiopulmonary diseases, including asthma and asthma-like disorders, there seems to be a continuous spectrum of symptoms and mechanisms integrated in a single asthma syndrome.

Coupling of dyspnea perception and tachypneic breathing during hypercapnia

Respiratory rhythm is susceptible to behavioral influences including emotions. Since laboratory dyspnea induces negative emotions, we examined whether tachypneic breathing occurs in relation to perception of dyspnea during CO(2) rebreathing (n=21). Dyspnea intensity scored by a visual analog scale and respiratory frequency started to increase rapidly once the intensity of the stimuli exceeded a threshold for the end-tidal CO(2) fraction. The thresholds for dyspnea and respiratory frequency were similar (7.5±0.1% and 7.6±0.2% of the end-tidal CO(2) fraction, respectively), while the threshold for tidal volume (8.0±0.2%), when the tidal volume had stabilized, was significantly higher than the thresholds for dyspnea (p<0.01) and respiratory frequency (p<0.05). A positive correlation was found between the thresholds for dyspnea and respiratory frequency (r=0.81, p<0.001), and these thresholds showed good agreement on a Bland-Altman plot. These findings suggest that the start of tachypneic breathing is coupled with the threshold for dyspnea.