Language of dyspnea in assessment of patients with acute asthma treated with nebulized albuterol

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.

Severity and phenotypes of dyspnea in asthma: Impact of comorbidities

BACKGROUND

Dyspnea is a common but non-specific symptom of asthma, which in particular may be related to anxiety and hyperventilation syndrome, two frequent comorbidities of asthma.

METHODS

We conducted a prospective multicentric cohort study in dyspneic asthmatic adults. Dyspnea was assessed using the Multidimensional Dyspnea Profile questionnaire. We described the sensory (QS) and affective (A2) domains of dyspnea and investigated the effect of poor asthma control, hyperventilation and anxiety on each dimension at baseline and after 6 months.

RESULTS

We included 142 patients (65.5% women, age: 52 years). Dyspnea was severe and predominated on its sensory domain (median QS: 27/50; A2: 15/50). Uncontrolled asthma (ACQ≥1.5), hyperventilation symptoms (Nijmegen≥23) and anxiety (HAD-A≥10) were present in 75%, 45.7% and 39% of cases, respectively. Hyperventilation symptoms were associated with higher QS and A2 scores: QS at 28.4(10.7) vs. 21.7(12.8) (p = 0.001) and A2 at 24(14) vs. 11.3(11) (p < 0.001) in patients with vs. without hyperventilation symptoms. Anxiety was only associated with increased A2 (27(12.3) vs. 10.9(11), p < 0.001). At 6 months, QS and A2 decreased of 7 and 3 points, respectively, in relation with changes in ACQ-6 and Nijmegen scores as well as the HAD-A score for A2.

CONCLUSION

In breathless asthmatics, dyspnea is severe and worsened but differentially modulated by hyperventilation symptoms and anxiety. A multidimensional phenotyping of dyspnea in asthmatics could be useful to understand its origins and personalize treatment.

Single dose of budesonide/formoterol turbuhaler compared to salbutamol pMDI for speed of bronchodilator onset in asthma: a randomised cross-over trial

OBJECTIVE

To compare bronchodilator response after to salbutamol and budesonide/formoterol in adults with stable asthma.

METHODS

A double-blind, cross-over, single-centre, placebo-controlled, non-inferiority trial. Adults with stable asthma were randomised to different orders of two treatment regimens: two actuations of placebo via MDI and one actuation of budesonide/formoterol 200/6 µg via turbuhaler; and one actuation of placebo turbuhaler and two actuations of salbutamol 100 µg via MDI. The primary outcome measure was FEV1 after 2 min. Secondary outcome measures included FEV1, mBorg Dyspnoea Scale score and visual analogue score for breathlessness over 30 min.

RESULTS

Forty-nine of 50 potential participants were randomised. One participant withdrew following the first intervention visit and another could not be randomised due to COVID-19 restrictions. The mean (SD) change from baseline FEV1 2 min after treatment administration for budesonide/formoterol and salbutamol was 0.08 (0.14) L, n=49, and 0.17 (0.18) L, n=48, respectively, mean (95% CI) paired difference of -0.097 L (-0.147 to -0.047), p=0.07, against a non-inferiority bound of -0.06 L. In the secondary analysis, FEV1 over 30 min was lower for budesonide/formoterol compared with salbutamol, difference (95% CI): -0.10 (-0.12 to -0.08) L, p<0.001. There were no differences in Visual Analogue Scale score or mBorg Dyspnoea Scale score between treatments.

CONCLUSION

The results do not support the primary hypothesis of non-inferiority at the boundary of -0.06 L for the difference between budesonide/formoterol 200/6 µg compared with salbutamol 200 µg for FEV1 at 2 min, and could be consistent with inferiority with a p value of 0.07. For the secondary analysis of FEV1 measurements over time, the FEV1 was higher with salbutamol.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry (ACTRN 12619001387112).

'The body says it': the difficulty of measuring and communicating sensations of breathlessness

Breathlessness is a sensation affecting those living with chronic respiratory disease, obesity, heart disease and anxiety disorders. The Multidimensional Dyspnoea Profile is a respiratory questionnaire which attempts to measure the incommunicable different sensory qualities (and emotional responses) of breathlessness. Drawing on sensorial anthropology we take as our object of study the process of turning sensations into symptoms. We consider how shared cultural templates of 'what counts as a symptom' evolve, mediate and feed into the process of bodily sensations becoming a symptom. Our contribution to the field of sensorial anthropology, as an interdisciplinary collaboration between history, anthropology and the medical humanities, is to provide a critique of how biomedicine and cultures of clinical research have measured the multidimensional sensorial aspects of breathlessness. Using cognitive interviews of respiratory questionnaires with participants from the Breathe Easy groups in the UK, we give examples of how the wording used to describe sensations is often at odds with the language those living with breathlessness understand or use. They struggle to comprehend and map their bodily experience of sensations associated with breathlessness to the words on the respiratory questionnaire. We reflect on the alignment between cognitive interviewing as a method and anthropology as a disciplinary approach. We argue biomedicine brings with it a set of cultural assumptions about what it means to measure (and know) the sensorial breathless body in the context of the respiratory clinic (clinical research). We suggest the mismatch between the descriptions (and confusion) of those responding to the respiratory questionnaire items and those selecting the vocabularies in designing it may be symptomatic of a type of historical testimonial epistemic injustice, founded on the prioritisation of clinical expertise over expertise by experience.

The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles

Asthma often worsens at night. To determine if the endogenous circadian system contributes to the nocturnal worsening of asthma, independent of sleep and other behavioral and environmental day/night cycles, we studied patients with asthma (without steroid use) over 3 wk in an ambulatory setting (with combined circadian, environmental, and behavioral effects) and across the circadian cycle in two complementary laboratory protocols performed in dim light, which separated circadian from environmental and behavioral effects: 1) a 38-h "constant routine," with continuous wakefulness, constant posture, 2-hourly isocaloric snacks, and 2) a 196-h "forced desynchrony" incorporating seven identical recurring 28-h sleep/wake cycles with all behaviors evenly scheduled across the circadian cycle. Indices of pulmonary function varied across the day in the ambulatory setting, and both laboratory protocols revealed significant circadian rhythms, with lowest function during the biological night, around 4:00 AM, uncovering a nocturnal exacerbation of asthma usually unnoticed or hidden by the presence of sleep. We also discovered a circadian rhythm in symptom-based rescue bronchodilator use (β2-adrenergic agonist inhaler) whereby inhaler use was four times more likely during the circadian night than day. There were additive influences on asthma from the circadian system plus sleep and other behavioral or environmental effects. Individuals with the lowest average pulmonary function tended to have the largest daily circadian variations and the largest behavioral cycle effects on asthma. When sleep was modeled to occur at night, the summed circadian, behavioral/environmental cycle effects almost perfectly matched the ambulatory data. Thus, the circadian system contributes to the common nocturnal worsening of asthma, implying that internal biological time should be considered for optimal therapy.

Nasal High-flow Oxygen Versus Conventional Oxygen Therapy for Acute Severe Asthma Patients: A Pilot Randomized Controlled Trial

Background

Nasal high flow (NHF) has demonstrated efficacy in relieving dyspnea in various patients with hypoxemic and hypercapnic respiratory failure. It may also reduce dyspnea in patients with acute severe asthma in the emergency department (ED). The aim of the study was to compare the efficacy of NHF with conventional oxygen therapy (COT) in improving dyspnea in acute severe asthma patients with hypoxemia in the ED.

Methods

This pilot nonblinded randomized controlled trial was conducted involving 37 patients aged ≥ 18 years with acute severe asthma and hypoxemia in the ED of Siriraj Hospital, Bangkok, Thailand (TCTR20180926003). The participants were randomly allocated to receive either COT (n = 18) or NHF (n = 19) for 120 minutes. The primary outcome was comparing the intervention effects on the patients’ degree of dyspnea measured using the modified Borg scale (MBS). The secondary outcomes were comparing the interventions based on the numeric rating scale (NRS) of dyspnea, the dyspnea scale assessing accessory muscle use, vital signs, and blood gas results.

Results

The intention‐to‐treat analysis included 37 patients (COT group n = 18 and NHF group n = 19). The baseline mean MBS was 7.8 in both groups. At 120 minutes, the mean (±SD) MBSs in patients receiving COT and NHF were 3.3 (±2.5) and 1.4 (±2.5), respectively (mean difference = 1.9 [95% CI = 0.2 to 3.8], p = 0.043). The trends in NRS and dyspnea score results were similar to those of MBS. Respiratory rates were lower with NHF (mean difference = 4.7 [95% CI = 1.5 to 7.8], p = 0.001). No between‐ or within‐group differences in blood gas results were found.

Conclusion

Nasal high flow reduced the severity of dyspnea and respiratory rate in hypoxemic patients with acute severe asthma in the ED.

A Multidimensional Profile of Dyspnea in Hospitalized Patients

BACKGROUND

Dyspnea is prevalent among hospitalized patients but little is known about the experience of dyspnea among inpatients. We sought to characterize the multiple sensations and associated emotions of dyspnea in patients admitted with dyspnea to a tertiary care hospital.

METHODS

We selected patients who reported breathing discomfort of at least 4/10 on admission (10 = unbearable). Research staff recruited 156 patients within 24 hours of admission and evaluated daily patients' current and worst dyspnea with the Multidimensional Dyspnea Profile; patients participated in the study 2.6 days on average. The Multidimensional Dyspnea Profile assesses overall breathing discomfort (A₁), intensity of five sensory qualities of dyspnea, and 5 negative emotional responses to dyspnea. Patients were also asked to rate whether current levels of dyspnea were "acceptable."

RESULTS

At the time of the first research interview, patients reported slight to moderate dyspnea (A₁ median 4); however, most patients reported experiencing severe dyspnea in the 24 hours before the interview (A₁ mean 7.8). A total of 54% of patients with dyspnea ≥4 on day 1 found the symptom unacceptable. The worst dyspnea each day in the prior 24 hours usually occurred at rest. Dyspnea declined but persisted through hospitalization for most patients. "Air hunger" was the dominant sensation, especially when dyspnea was strong (>4). Anxiety and frustration were the dominant emotions associated with dyspnea.

CONCLUSIONS

This first multidimensional portrait of dyspnea in a general inpatient population characterizes the sensations and emotions dyspneic patients endure. The finding that air hunger is the dominant sensation of severe dyspnea has implications for design of laboratory models of these sensations and may have implications for targets of palliation of symptoms.

Exertional Dyspnea in Childhood: Is There an Iceberg Beneath the Apex?

This essay expounds on fundamental, quantitative elements of the exercise ventilation in children, which was the subject of the Tom Rowland Lecture given at the NASPEM 2018 Conference. Our knowledge about how much ventilation rises during aerobic exercise is reasonably solid; our understanding of its governance is a work in progress, but our grasp of dyspnea and ventilatory limitation in children (if it occurs) remains embryonic. This manuscript summarizes ventilatory mechanics during dynamic exercise, then proceeds to outline our current understanding of mechanisms of dyspnea, particularly during exercise (exertional dyspnea). Most research in this field has been done in adults, and the vast majority of these studies in patients with chronic obstructive pulmonary disease. To what extent conclusions drawn from this literature apply to children and adolescents-both healthy and those with cardiopulmonary disease-will be discussed. The few, recent, pertinent, pediatric studies will be reviewed in an attempt to provide an empirical basis for proposing a hypothetical model to study exertional dyspnea in youth. Just as somatic growth will have consequences for ventilatory and exercise capacity, so too will neural developmental plasticity and experience affect perception of dyspnea. Our path to understand how these evolving inputs and influences summate during a child's life will be Columbus' India.

Dyspnea in Children: What is driving it and how to approach it

Dyspnea in children has important physical and psychosocial impact. It is useful to define the quality of the dyspnea and quantify its magnitude in a child-friendly manner. Through careful history taking and physical examination, a targeted investigation can lead to identification of the cause and potential treatment. This article provides a framework for the clinical approach to dyspnea in children, including important information to gather during the history, physical assessment, how to quantify dyspnea, and choice and use of laboratory measurements.

Mechanisms, measurement and management of exertional dyspnoea in asthma: Number 5 in the Series "Exertional dyspnoea" Edited by Pierantonio Laveneziana and Piergiuseppe Agostoni

Asthma is a heterogeneous condition, with dyspnoea during exercise affecting individuals to a variable degree. This narrative review explores the mechanisms and measurement of exertional dyspnoea in asthma and summarises the available evidence for the efficacy of various interventions on exertional dyspnoea. Studies on the mechanisms of dyspnoea in asthma have largely utilised direct bronchoprovocation challenges, rather than exercise, which may invoke different physiological mechanisms. Thus, the description of dyspnoea during methacholine challenge can differ from what is experienced during daily activities, including exercise. Dyspnoea perception during exercise is influenced by many interacting variables, such as asthma severity and phenotype, bronchoconstriction, dynamic hyperinflation, respiratory drive and psychological factors. In addition to the intensity of dyspnoea, the qualitative description of dyspnoea may give important clues as to the underlying mechanism and may be an important endpoint for future interventional studies. There is currently little evidence demonstrating whether pharmacological or non-pharmacological interventions specifically improve exertional dyspnoea, which is an important area for future research.

Addressing unmet needs in understanding asthma mechanisms: From the European Asthma Research and Innovation Partnership (EARIP) Work Package (WP)2 collaborators

Asthma is a heterogeneous, complex disease with clinical phenotypes that incorporate persistent symptoms and acute exacerbations. It affects many millions of Europeans throughout their education and working lives and puts a heavy cost on European productivity. There is a wide spectrum of disease severity and control. Therapeutic advances have been slow despite greater understanding of basic mechanisms and the lack of satisfactory preventative and disease modifying management for asthma constitutes a significant unmet clinical need. Preventing, treating and ultimately curing asthma requires co-ordinated research and innovation across Europe. The European Asthma Research and Innovation Partnership (EARIP) is an FP7-funded programme which has taken a co-ordinated and integrated approach to analysing the future of asthma research and development. This report aims to identify the mechanistic areas in which investment is required to bring about significant improvements in asthma outcomes.

Exertional Dyspnoea in Chronic Respiratory Diseases: From Physiology to Clinical Application

Dyspnoea is a complex, highly personalized and multidimensional sensory experience, and its underlying cause and mechanisms are still being investigated. Exertional dyspnoea is one of the most frequently encountered symptoms of patients with cardiopulmonary diseases, and is a common reason for seeking medical help. As the symptom usually progresses with the underlying disease, it can lead to an avoidance of physical activity, peripheral muscle deconditioning and decreased quality of life. Dyspnoea is closely associated with quality of life, exercise (in)tolerance and prognosis in various conditions, including chronic obstructive pulmonary disease, heart failure, interstitial lung disease and pulmonary hypertension, and is therefore an important therapeutic target. Effective management and treatment of dyspnoea is an important challenge for caregivers, and therapeutic options that attempt to reverse its underlying cause have been only partially successful This "review" will attempt to shed light on the physiological mechanisms underlying dyspnoea during exercise and to translate/apply them to a broad clinical spectrum of cardio-respiratory disorders.

Determining the cause of dyspnoea: linguistic and biological descriptors

Dyspnoea is the most common symptom of patients with cardio-respiratory diseases. It is a generic term related to different pathophysiological abnormalities that may result in different qualities of respiratory discomfort, defined by specific verbal descriptors for a specific diagnosis. Often it is difficult to distinguish the underlying pathology of dyspnoea, eg, either from chronic heart failure (CHF) or from other respiratory causes. The discovery of the endocrine function of the heart, as well as the development of accurate and feasible assay methods allow the use of cardiac natriuretic hormones in the assessment of cardiovascular diseases, namely acute coronary syndromes and heart failure. It is advisable to measure cardiac natriuretic hormones in order to exclude or suggest the diagnosis of CHF in patients with a suspicious diagnosis, but with ambiguous signs and symptoms or manifestations that can be confused with other pathologies (like chronic obstructive pulmonary disease). The most common symptom of patients with cardio-respiratory diseases is dyspnoea, a 'difficult, laboured, uncomfortable breathing'. Dyspnoea has been defined as 'a term used to characterize a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. The experience derives from interactions among multiple physiological, psychological, social and environmental factors, and may induce secondary physiological and behavioural responses'. Breathlessness is characterized by measurable intensity and qualitative dimensions, which may vary depending on the individual, the underlying disease, and other circumstances.3 The neurophysiological basis of dyspnoea relies on receptors in the airways lung parenchyma, respiratory muscles together with chemoreceptors providing sensory feedback via vagal, phrenic and intercostal nerves to the spinal cord, medulla and higher centres. Breathlessness is based on different pathophysiolagical abnormalities that may result in different qualities of respiratory discomfort, which are defined by specific verbal descriptors related to a specific diagnosis. Nevertheless different diseases may share the same descriptors. There is no clear relationship between the qualitative descriptors of dyspnoea and the quantitative intensity among the patient groups: different diseases may be distinguished by quality but not intensity of the sensation. Differences in languages, in races, cultures, gender, and in the manner in which concepts or symptoms are held can all influence the idea, quality and intensity of dyspnoea.

Activity limitation and exertional dyspnea in adult asthmatic patients: What do we know?

Limitation of activity is the most cited symptom described by uncontrolled asthma patients. Assessment of activity limitation can be undertaken through several ways, more or less complex, subjective or objective. Yet little is known about the link between patients sensations and objective measurements. The present review reports the current knowledge regarding activity limitation and symptom perception (i.e., exertional dyspnea) in adult patients with asthma. This work is based on references indexed by PubMed, irrespective of the year of publication. Overall, patients with stable asthma do not have a more sedentary lifestyle than healthy subjects. However, during a cycle ergometric test, the maximal load is reduced when FEV1, FVC and muscle strengths are decreased. Additionally, during the six-minute walking test, mild asthma patients walk less than healthy subjects even if the minimal clinically important difference is not reached. The major complaint of asthma patients when exercising is dyspnea that is mainly related to the inspiratory effort and also to dynamic hyperinflation in some circumstances. Finally, the administration of bronchodilator does not improve the ventilatory pattern and the exercise capacity of asthma patients and little is known on its effect on exertional dyspnea. The present review allows to conclude that until now there is no gold standard test allowing the objective assessment of "activity limitation and exertional dyspnea" in asthma patients.

Prospective use of descriptors of dyspnea to diagnose common respiratory diseases

BACKGROUND

Although patients may find it difficult to describe their breathing discomfort, most are able to select statements among a list to describe their experience. The primary objective of this study was to examine sensitivity and specificity of descriptors of breathing discomfort prospectively in patients with common respiratory conditions as well as those patients who had refractory dyspnea.

METHODS

Outpatients answered "Yes" or "No" for each of 15 statements describing breathing discomfort, next selected the best three that most closely applied, and then completed the Hospital Anxiety Depression Scale-Anxiety subscale. Sensitivity, specificity, and predictive values were calculated for the descriptors by diagnosis.

RESULTS

"Work/effort" descriptors were selected as the best three by patients with COPD (n = 68), respiratory muscle weakness (n = 11), and refractory dyspnea (n = 17). Along with "work/effort" descriptors, "My chest feels tight" was among the best three in asthma (n = 22), with 38% sensitivity and 88% specificity. Along with "work/effort" descriptors, "My breathing is shallow" was among the best three in interstitial lung disease (n = 8), with 33% sensitivity and 84% specificity. Affective descriptors "frightening" (61% vs 31%, P = .002) and "awful" (66% vs 37%, P = .004) were reported more frequently in those with high anxiety scores compared with low anxiety scores.

CONCLUSIONS

Although no descriptor achieved satisfactory sensitivity and specificity for identifying a particular condition, chest "tightness" was unique for asthma, whereas "shallow breathing" was unique for interstitial lung disease. Affective descriptors were associated with high anxiety scores.

Multidimensional Dyspnea Profile: an instrument for clinical and laboratory research

There is growing awareness that dyspnoea, like pain, is a multidimensional experience, but measurement instruments have not kept pace. The Multidimensional Dyspnea Profile (MDP) assesses overall breathing discomfort, sensory qualities, and emotional responses in laboratory and clinical settings. Here we provide the MDP, review published evidence regarding its measurement properties and discuss its use and interpretation. The MDP assesses dyspnoea during a specific time or a particular activity (focus period) and is designed to examine individual items that are theoretically aligned with separate mechanisms. In contrast, other multidimensional dyspnoea scales assess recalled recent dyspnoea over a period of days using aggregate scores.

Previous psychophysical and psychometric studies using the MDP show that: 1) subjects exposed to different laboratory stimuli could discriminate between air hunger and work/effort sensation, and found air hunger more unpleasant; 2) the MDP immediate unpleasantness scale (A₁) was convergent with common dyspnoea scales; 3) in emergency department patients, two domains were distinguished (immediate perception, emotional response); 4) test–retest reliability over hours was high; 5) the instrument responded to opioid treatment of experimental dyspnoea and to clinical improvement; 6) convergent validity with common instruments was good; and 7) items responded differently from one another as predicted for multiple dimensions.

The Multidimensional Dyspnea Profile provides a unified, reliable instrument for both clinical and laboratory researchhttp://ow.ly/Ix8ic

Why aren't we doing better in asthma: time for personalised medicine?

After decades of improvement, asthma outcomes have stalled. Mortality, hospitalisations, exacerbations and symptom control remain sub-optimal. In controlled trials, most patients gain high levels of control, but in ‘real-life’ routine clinical practice most patients do not. Avoidable factors are found in most asthma deaths and hospital admissions. This perspective paper considers and contextualises the factors underlying poor asthma outcomes, and it suggests approaches that could improve the situation. Factors discussed include severe, therapy-resistant disease and the role of new and upcoming pharmacological therapies in improving outcomes. These are likely to be beneficial when targeted on patients with severe disease and discrete phenotypic characteristics, identified through biomarkers. However, for the majority of patients treated in the community, they are unlikely to be used widely, and better use of current therapy classes will be more important. Non-adherence with regular inhaled corticosteroid treatment and over-use of rescue bronchodilators are common, and many patients have poor inhaler technique. Self-management is frequently poor, particularly in those with psychosocial disadvantages and co-morbidities. Communication between clinicians and patients is sometimes poor, with failure to detect avoidable poor control and non-adherence, and failure to provide the necessary information and education to support efficient self-management. Strategies for improving monitoring and clinician–patient interactions to allow personalised treatment are considered. These strategies have the potential to allow individual patient needs to be recognised and efficient targeting of the variety of effective pharmacological and non-pharmacological interventions that we possess, which has the potential to improve both individual and population outcomes.

Breathing exercises for asthma

Educational aims

To summarise the evidence of the role of breathing control approaches in the management of asthma

To provide information on the content of evidence-based breathing exercises programmes

Summary

Asthma is a complex, multi-dimensional condition that affects patients in many ways. Having asthma is inherently stressful and psychological problems are common and associated with poor asthma outcomes. Although most patients in clinical trials can achieve high levels of control with optimised pharmacotherapy, in “real-life” practice, poor control is common, with over-reliance on rescue bronchodilator medication and ongoing symptoms and quality-of-life impairment. Many patients are interested in non-pharmacological treatments to improve asthma control, particularly breathing control exercises but, until recently, the evidence base has been inadequate. The place of breathing exercises has been controversial, partly because some proponents have made exaggerated, implausible claims of effectiveness. Recent evidence, however, has resulted in endorsement of breathing exercises as add-on treatment in asthma in systematic reviews and guidelines.

This review summarises the current evidence of effectiveness of breathing exercises programmes as an adjuvant treatment to pharmacological strategies for people with asthma. The types of breathing training programmes used and the content of effective programmes are discussed. We conclude that patients whose asthma continues to cause symptoms and quality-of-life impairment, despite adequate pharmacological treatment, or who have high bronchodilator use, should be offered access to an effective breathing training programme as a part of holistic, integrated asthma care.

Key points

Asthma is frequently poorly controlled despite effective modern medication

Psychological factors can be as important as physiological ones in affecting symptom perception and disease impact

Breathing exercises can improve patient-reported outcomes and psychological state

Breathing exercises should be offered to all asthma patients with symptoms or impaired quality of life despite standard treatment

Different respiratory behaviors disclosed by induced bronchoconstriction in mild asthma patients

Respiratory responses to bronchoconstriction in asthma have been partially assessed and their significance is unclear. In 44 mild asthma patients we investigated respiratory responses during increasing levels of methacholine-induced bronchoconstriction. Inspiratory muscle activity, tidal volume, inspiratory and expiratory times were continuously monitored; breathing discomfort was rated. Mean inspiratory flow, respiratory frequency and ventilation were calculated. Lung function was assessed prior to and at maximum bronchoconstriction. Bronchoconstriction "dose-dependently" increased inspiratory muscle activity and breathing discomfort (P<0.01). In 37 patients (84.1%), the increase in inspiratory muscle activity was associated with increases in mean inspiratory flow and ventilation (P<0.01) because of selective rises in breathing depth (volume responders), or rate (frequency responders) or both (dual responders). In seven patients (15.9%) ventilation was unchanged. Individual respiratory responses were reproducible. With bronchoconstriction, frequency responders displayed greater hyperinflation and stronger breathing discomfort than volume responders (P<0.01). Analysis of the responses to induced bronchoconstriction disclosed distinctive and reproducible respiratory adjustments that may identify functionally different asthma subpopulations.

Test-retest reliability of multidimensional dyspnea profile recall ratings in the emergency department: a prospective, longitudinal study

BACKGROUND

Dyspnea is among the most common reasons for emergency department (ED) visits by patients with cardiopulmonary disease who are commonly asked to recall the symptoms that prompted them to come to the ED. The reliability of recalled dyspnea has not been systematically investigated in ED patients.

METHODS

Patients with chronic or acute cardiopulmonary conditions who came to the ED with dyspnea (N = 154) completed the Multidimensional Dyspnea Profile (MDP) several times during the visit and in a follow-up visit 4 to 6 weeks later (n = 68). The MDP has 12 items with numerical ratings of intensity, unpleasantness, sensory qualities, and emotions associated with how breathing felt when participants decided to come to the ED (recall MDP) or at the time of administration ("now" MDP). The recall MDP was administered twice in the ED and once during the follow-up visit. Principal components analysis (PCA) with varimax rotation was used to assess domain structure of the recall MDP. Internal consistency reliability was assessed with Cronbach's alpha. Test-retest reliability was assessed with intraclass correlation coefficients (ICCs) for absolute agreement for individual items and domains.

RESULTS

PCA of the recall MDP was consistent with two domains (Immediate Perception, 7 items, Cronbach's alpha = .89 to .94; Emotional Response, 5 items; Cronbach's alpha = .81 to .85). Test-retest ICCs for the recall MDP during the ED visit ranged from .70 to .87 for individual items and were .93 and .94 for the Immediate Perception and Emotional Response domains. ICCs were much lower for the interval between the ED visit and follow-up, both for individual items (.28 to .66) and for the Immediate Perception and Emotional Response domains (.72 and .78, respectively).

CONCLUSIONS

During an ED visit, recall MDP ratings of dyspnea at the time participants decided to seek care in the ED are reliable and sufficiently stable, both for individual items and the two domains, that a time lag between arrival and questionnaire administration does not critically affect recall of perceptual and emotional characteristics immediately prior to the visit. However, test-retest reliability of recall over a 4- to 6-week interval is poor for individual items and significantly attenuated for the two domains.

An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea

BACKGROUND

Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome.

PURPOSE

The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea.

METHODS

An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members.

RESULTS

Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains.

CONCLUSIONS

Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea

BACKGROUND

Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome.

PURPOSE

The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea.

METHODS

An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members.

RESULTS

Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains.

CONCLUSIONS

Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

Validation of a three-factor measurement model of dyspnea in hospitalized adults with heart failure

OBJECTIVE

The purpose of this study was to validate a 3-factor measurement model of dyspnea sensory quality (WORK-EFFORT, TIGHTNESS, SMOTHERING-AIR HUNGER) originally derived in patients with exacerbated chronic obstructive pulmonary disease.

METHODS

In this validation study, adult patients with heart failure were enrolled after hospital admission (median hospital day 1) and asked to rate the intensity of dyspnea sensory quality descriptors on the day of enrollment (study day 1; N = 119) and in a recall version for the day of admission (study day 0; n = 97).

RESULTS

Confirmatory factor analysis demonstrated good model fit for both days. Cronbach's α for each factor was greater than .87 for both study days.

CONCLUSION

This is the first study to validate a previously specified measurement model of dyspnea sensory quality in an independent sample. Results indicate that measurement of dyspnea sensory quality in exacerbated cardiopulmonary disease does not necessarily require disease-specific questionnaires.

Assessment of dyspnea in asthma: validation of The Dyspnea-12

BACKGROUND

Dyspnea is a prominent symptom in asthma. The Dyspnea-12 (D-12), an instrument that quantifies breathlessness using 12 descriptors that tap the physical and affective aspects, has shown promise for the measurement of dyspnea in cardiorespiratory disease.

OBJECTIVE

We report the results of a study designed to test the validity and reliability of the D-12 in a population of patients with asthma.

METHODS

This cross-sectional study included 102 patients with asthma. Subjects completed the D-12, Hospital Anxiety and Depression scale, St. George's Respiratory Questionnaire (SGRQ), and Medical Research Council scale. Confirmatory factor analysis confirmed the two-component structure of the D-12 (i.e., seven items that tap the physical aspects of breathlessness and five items that tap the affective aspects).

RESULTS

The D-12 subscales had excellent internal reliability (Cronbach's alpha for the "physical" score was 0.94 and the affective score was 0.95). The D-12 physical component was more strongly correlated with SGRQ Symptoms (r = 0.648), SGRQ Activities (r = 0.635) and Medical Research Council grade (r = 0.636), while the affective component was more strongly correlated with SGRQ Impacts (r = 0.765) and Hospital Anxiety and Depression scale scores (anxiety r = 0.641 and depression r = 0.602).

CONCLUSION

This study supports validity of the D-12 for use in the assessment of dyspnea of patients with asthma. It assesses one of the most pertinent symptoms of asthma from two viewpoints-physical and affective.

Musculoskeletal dysfunction and pain in adults with asthma

BACKGROUND

The mechanical alterations related to the overload of respiratory muscles observed in adults with persistent asthma might lead to the development of chronic alterations in posture, musculoskeletal dysfunction and pain; however, these changes remain poorly understood.

OBJECTIVE

This study aimed to assess postural alignment, muscle shortening and chronic pain in adults with persistent asthma.

METHODS

This cross-sectional and controlled study enrolled 30 patients with mild (n = 17) and severe (n = 13) persistent asthma. Fifteen non-asthmatic volunteers were also assessed. Asthma was classified by the Global Initiative for Asthma (GINA) guidelines. Postural alignment and muscle shortening were evaluated by head and shoulder positions, chest wall mobility, and posterior (trunk and lower limb) muscle flexibility. In addition, the measures used were previously tested for their reproducibility. Pain complaints were also assessed.

RESULTS

In comparison with non-asthmatic subjects, patients with mild or severe persistent asthma held their head and shoulders more forward and had lower chest wall expansion, decreased shoulder internal rotation, and decreased thoracic spine flexibility. Chronic lower thoracic, cervical, and shoulder pain was significantly increased in patients with mild or severe asthma compared with non-asthmatic subjects (p < 0.05).

CONCLUSION

Adults with persistent asthma have musculoskeletal dysfunction and chronic pain that is independent of the severity of their disease but that might be related to their age at the onset of disease symptoms.

Descriptors of breathlessness in children with persistent asthma

BACKGROUND

In adult patients, the consistent use of language to describe dyspnea enhances patient-provider communication and contributes to diagnostic and therapeutic decisions. The objective of this research was to determine whether pediatric patients similarly display consistency in the language used to describe "uncomfortable awareness of breathing."

METHODS

One hundred children between the ages of 8 and 15 years with moderate to severe persistent asthma enrolled in an asthma education research program completed questionnaires regarding descriptors of asthma on each of two occasions. In addition to the breathlessness questionnaires, demographic information, self-reported asthma severity, ED visits, missed school days, anthropometrics, and spirometry were obtained for each participant.

RESULTS

Children were reliable in their choice of the descriptors that they applied to their breathing discomfort across two occasions, and they selected the same descriptors that were used by adults with asthma in previous studies. Children with greater self-reported asthma severity endorsed more descriptors to characterize breathing discomfort than did children with less severe asthma, but no differences were found among children based on demographic or anthropometric variables.

CONCLUSIONS

Children with moderate to severe persistent asthma are reliable in their choice of descriptors of breathlessness. Knowledge of their experience of symptoms may be helpful clinically in the assessment and management of asthma.

Validation of a verbal dyspnoea rating scale in the emergency department

OBJECTIVE

Use of a verbal dyspnoea rating scale in the emergency department (ED) has many potential benefits, providing information to clinicians otherwise not afforded by objective parameters. In the present study, we aimed to investigate the validity of a verbal dyspnoea rating scale, previously validated in the setting of cardiac stress tests, among patients presenting to the ED with acute shortness of breath (SOB).

METHODS

This was a prospective observational study conducted at an inner-urban adult tertiary hospital. A convenience sample of patients presenting with SOB to the ED had objective data collected at triage and 30 min later, including respiratory rate (RR), oxygen saturation (S(a)O(2)), heart rate (HR) and systolic blood pressure (SPB). These were correlated with the participants' subjective response to the question: 'On a scale from 0 to 10, how bad is your SOB, with zero being no SOB and 10 the worst SOB you could ever imagine?' Spearman correlations were then calculated between objective and subjective breathlessness measures.

RESULTS

For 253 breathless ED patients (mean age 60.6 years, 126 male), verbal dyspnoea scores at triage correlated with RR (r = 0.77, P < 0.001), S(a)O(2) (r =-0.43, P < 0.001), HR (r = 0.35, P < 0.001) and SPB (r = 0.19, P < 0.05). Thirty minutes later, correlations remained significant for RR (r = 0.74, P < 0.001), S(a)O(2) (r =-0.39, P < 0.001) and HR (r = 0.40, P < 0.001).

CONCLUSION

A verbal numerical SOB rating scale is a valid measure of breathlessness in the ED, and might therefore provide useful insight into a symptom that is otherwise unmeasurable.

Descriptors of dyspnea in obstructive lung diseases

In obstructive lung diseases such as asthma and COPD dyspnea is a common respiratory symptom with different characteristics given the different pathogenic mechanisms: in COPD initially it can occur during exertion but then it increases progressively along with the airflow obstruction, whereas in asthma it occurs episodically and is caused by transient bronchoconstriction.The language of dyspnea includes a large range of clinical descriptors which have been evaluated for their correlation (of one or several descriptors) with underlying physiologic/physiopathologic mechanisms. These studies were done in asthma rather than in COPD, and dyspnea descriptors were found to be useful in identifying patients with life-threatening asthma. However further studies are needed to further explore such descriptors and their clinical utility.This review discusses dyspnea mechanisms in various obstructive lung disease subsets as well as the descriptors of dyspnea and their utility in clinical practice.

Acute severe asthma: new approaches to assessment and treatment

The precise definition of a severe asthmatic exacerbation is an issue that presents difficulties. The term 'status asthmaticus' relates severity to outcome and has been used to define a severe asthmatic exacerbation that does not respond to and/or perilously delays the repetitive or continuous administration of short-acting inhaled beta(2)-adrenergic receptor agonists (SABA) in the emergency setting. However, a number of limitations exist concerning the quantification of unresponsiveness. Therefore, the term 'acute severe asthma' is widely used, relating severity mostly to a combination of the presenting signs and symptoms and the severity of the cardiorespiratory abnormalities observed, although it is well known that presentation does not foretell outcome. In an acute severe asthma episode, close observation plus aggressive administration of bronchodilators (SABAs plus ipratropium bromide via a nebulizer driven by oxygen) and oral or intravenous corticosteroids are necessary to arrest the progression to severe hypercapnic respiratory failure leading to a decrease in consciousness that requires intensive care unit (ICU) admission and, eventually, ventilatory support. Adjunctive therapies (intravenous magnesium sulfate and/or others) should be considered in order to avoid intubation. Management after admission to the hospital ward because of an incomplete response is similar. The decision to intubate is essentially based on clinical judgement. Although cardiac or respiratory arrest represents an absolute indication for intubation, the usual picture is that of a conscious patient struggling to breathe. Factors associated with the increased likelihood of intubation include exhaustion and fatigue despite maximal therapy, deteriorating mental status, refractory hypoxaemia, increasing hypercapnia, haemodynamic instability and impending coma or apnoea. To intubate, sedation is indicated in order to improve comfort, safety and patient-ventilator synchrony, while at the same time decrease oxygen consumption and carbon dioxide production. Benzodiazepines can be safely used for sedation of the asthmatic patient, but time to awakening after discontinuation is prolonged and difficult to predict. The most common alternative is propofol, which is attractive in patients with sudden-onset (near-fatal) asthma who may be eligible for extubation within a few hours, because it can be titrated rapidly to a deep sedation level and has rapid reversal after discontinuation; in addition, it possesses bronchodilatory properties. The addition of an opioid (fentanyl or remifentanil) administered by continuous infusion to benzodiazepines or propofol is often desirable in order to provide amnesia, sedation, analgesia and respiratory drive suppression. Acute severe asthma is characterized by severe pulmonary hyperinflation due to marked limitation of the expiratory flow. Therefore, the main objective of the initial ventilator management is 2-fold: to ensure adequate gas exchange and to prevent further hyperinflation and ventilator-associated lung injury. This may require hypoventilation of the patient and higher arterial carbon dioxide (PaCO(2)) levels and a more acidic pH. This does not apply to asthmatic patients intubated for cardiac or respiratory arrest. In this setting the post-anoxic brain oedema might demand more careful management of PaCO(2) levels to prevent further elevation of intracranial pressure and subsequent complications. Monitoring lung mechanics is of paramount importance for the safe ventilation of patients with status asthmaticus. The first line of specific pharmacological therapy in ventilated asthmatic patients remains bronchodilation with a SABA, typically salbutamol (albuterol). Administration techniques include nebulizers or metered-dose inhalers with spacers. Systemic corticosteroids are critical components of therapy and should be administered to all ventilated patients, although the dose of systemic corticosteroids in mechanically ventilated asthmatic patients remains controversial. Anticholinergics, inhaled corticosteroids, leukotriene receptor antagonists and methylxanthines offer little benefit, and clinical data favouring their use are lacking. In conclusion, expertise, perseverance, judicious decisions and practice of evidence-based medicine are of paramount importance for successful outcomes for patients with acute severe asthma.

Asthma: Pathophysiology and Diagnosis

Although asthma is a common disorder affecting approximately 7.8% of the United States population (Schiller et al. 2006) or 23 million Americans, the pathogenesis of this disease remains to be fully elucidated. Extensive research over the last few decades has yielded a better understanding of asthma. We know that the basic features of asthma include episodic airways inflammation, airways hyperresponsiveness, and mucous hypersecretion. Although we understand the basic clinical features of asthma, the links between symptoms, physical signs, and underlying pathophysiological mechanisms are still being delineated. Asthma is a heterogeneous disease process with varying phenotypes and presentations. In this chapter, we will briefly explore some major theories of asthma pathogenesis, both new and old. We will also explore how understanding the pathophysiology of asthma can help us to understand the symptoms and presentation of asthma, as well as the best strategies for diagnosing this disease.

The multiple dimensions of dyspnea: review and hypotheses

Although dyspnea is a common and troubling symptom, our understanding of the neurophysiology of dyspnea is woefully incomplete. Most measurements of dyspnea treat it as a single entity. Although the multidimensional dyspnea concept has been mentioned for many decades, only recently has the concept been the subject of experimental tests. Emerging evidence has begun to favor the hypothesis that dyspnea comprises multiple dimensions or components that can be measured as different entities. Most recently, studies have begun to show that there is a separable 'affective dimension' (i.e. unpleasantness and emotional impact). Understanding of the multidimensional measurement of pain is far in advance of dyspnea, and has enabled progress in the neurophysiology of pain, including identification of separate neural structures subserving various elements of pain perception. We propose here a multidimensional model of dyspnea based on a state-of-the-art pain model, and review existing evidence in the light of this model.

Review of dyspnoea quantification in the emergency department: is a rating scale for breathlessness suitable for use as an admission prediction tool?

Acute shortness of breath is a potential marker of serious cardiopulmonary disease and requires rapid assessment. In our current health-care system, increasing pressure on the ED to limit costs and waiting times has resulted in the development of many clinical decision aids and admission prediction tools designed to assist ED physicians in meeting these demands. However, most of these tools are disease specific, and none are currently available for application to patients presenting to the ED with shortness of breath. Although somewhat limited, current evidence supports the utilization of a simple dyspnoea rating scale, to assist in the streamlining of clinical severity assessments and urgency evaluations, and to potentially provide useful information to facilitate rapid and accurate site-of-care decisions in this setting.

A prospective and randomized study for improvement of acute asthma by non-invasive positive pressure ventilation (NPPV)

OBJECTIVE

We hypothesized that non-invasive positive pressure ventilation (NPPV) would improve an acute asthma attack in mild to moderate cases without bronchodilator therapy.

METHODOLOGY

A total of 44 eligible patients with acute asthma of mild to moderate severity who had acute attacks were randomly allocated to a NPPV (n=30) or control group (n=14). Both groups received intravenous infusion of hydrocortisone prior to the study. Patients in the NPPV group were divided into two subgroups at random: a high- (n=16) and a low-pressure group (n=14). The former had a fixed expiratory positive airway pressure and inspiratory positive airway pressure of 6 cmH2O and 8 cmH2O, respectively, while the latter had levels of 4 cmH2O and 6 cmH2O, respectively. Effects on the following variables were assessed: FEV(1), oxygen saturation, heart rate, respiratory rate, scores of accessory muscle use and wheezing by auscultation, modified Borg scale score, and mean intra-airway pressure on the monitor.

RESULTS

A total of 26 patients completed the study in the NPPV group. The mean percent change in FEV(1) significantly improved after 40 minutes in the high-pressure group compared with that in the control group (p<0.0001). Similar significant improvements in modified Borg scale score and physical examination findings were observed in the high- and low-pressure groups. None of the patients required re-hospitalization or return to the emergency room in either the NPPV or control group.

CONCLUSION

We conclude that higher inflation pressure on NPPV led to clinical improvement in patients with acute asthma attacks of mild to moderate severity.

Perception of airway obstruction and airway inflammation in asthma: a review

Dyspnea has a multifactorial nature and the exact mechanism that causes breathlessness in asthma is not fully understood. There is compelling evidence that factors other than merely mechanical ones take part in the pathophysiology of breathlessness. Some recent reports attribute airway inflammation, which may contribute to the unexplained variability in the perception of dyspnea associated with bronchoconstriction. Eosinophil airway inflammation has been proposed as a determinant of breathlessness via mechanisms affecting either the mechanical pathways that control breathlessness or the afferent nerves involved in perception of dyspnea. In this review, data on the interrelation between inflammation and dyspnea sensation and the impact of treatment on dyspnea sensation are discussed. We conclude that regardless of whether mechanical or chemical inflammatory factors are involved, much variability in dyspnea scores remains unexplained.

[Descriptors of breathlessness in Mexican Spanish]

OBJECTIVE

Breathlessness is the most common symptom of cardiovascular or pulmonary disease. The term encompasses a wide range of descriptors used by patients, however. Identifying those descriptors can be useful for analyzing symptoms and understanding how they arise. The aim of this study was to characterize the descriptors of breathlessness used in Mexican Spanish and to consider their association with various states of respiratory distress and cardiovascular or pulmonary disease.

MATERIAL AND METHODS

A questionnaire was based on 21 descriptors of breathlessness, some of which had no equivalents in English. The subjects included 15 healthy individuals during a cardiopulmonary stress test, 13 healthy subjects after a carbon dioxide rebreathing procedure, and 10 healthy women during pregnancy. We also included 16 patients with confirmed heart disease in stable condition, 15 patients during exacerbation of asthma, 20 with stable chronic obstructive pulmonary disease, and 15 with diffuse interstitial lung disease also in stable condition. Descriptors of breathlessness were then grouped based on the results of cluster analysis.

RESULTS

Seven clusters of phrasal descriptors were identified as possibly representative of types of dyspnea. These clusters of descriptors were categorized as follows: agitation, suffocation, smothering, inhalation, exhalation, panting, and rapidity. Associations between types of dyspnea and the groups of participants were identified based on how frequently they used the terms.

CONCLUSIONS

At least 7 clusters or groups of descriptors of breathlessness were identified as equivalent to 7 types of dyspnea; some items have no equivalent in English. Healthy subjects with respiratory distress or certain groups of patients with cardiovascular or pulmonary disease are associated with certain types of dyspnea.

Is there a link between the qualitative descriptors and the quantitative perception of dyspnea in asthma?

BACKGROUND

There is no obvious link between qualitative descriptors and overall intensity of dyspnea during bronchoconstriction in patients with asthma.

AIMS

To determine whether qualitative and quantitative perception of methacholine-induced bronchoconstriction independently contribute to characterizing clinically stable asthma.

MATERIAL AND METHODS

We assessed changes in inspiratory capacity, and quantitative (by Borg scale) and qualitative (by a panel of eight dyspnea descriptors) sensations of dyspnea at 20 to 30% fall in FEV(1) during methacholine inhalation in 49 asthmatics. Furthermore, we calculated the level of perception of bronchoconstriction at 20% fall in FEV(1) (PB(20)).

RESULTS

Descriptors selected by patients during methacholine inhalation allowed us to define three language subgroups: (1) chest tightness (subgroup A, n = 21); (2) work/effort (subgroup B, n = 7); and (3) both descriptors (subgroup C, n = 13). Eight of the 49 patients (subgroup D) were not able to make a clear-cut distinction among descriptors. The subgroups exhibited similar function at baseline and during methacholine inhalation. Most importantly, patients selected chest tightness to a greater extent (42.85%), and work/effort (14.3%) and both descriptors (26.5%) to a lesser extent at the lowest level of bronchoconstriction (FEV(1) fall < 10%) as at 20% fall in FEV(1). Thirty-two patients were normoperceivers (PB(20) > or = 1.4 to < 5 arbitrary units [au]), 7 patients were hyperperceivers (PB(20) > or = 5 au), and 10 patients were hypoperceivers (PB(20) < 1.4 au). Language subgroups were equally distributed across the perceiver subgroups.

CONCLUSIONS

In patients with clinically stable asthma, PB(20) and language of dyspnea independently contribute to defining the condition of the disease. However, the possibility that this independence may be due to a beta-error should be taken into account.

Dyspnea and asthma

PURPOSE OF REVIEW

Dyspnea--the perception of respiratory discomfort--is a primary symptom of asthma. This review examines possible ways to link mechanisms, measurement and treatment that will increase our understanding of this condition.

RECENT FINDINGS

Functional neuroimaging methods have proven to be powerful tools that serve as advanced models of sensor motor brain function. Studies examining functional neuroimaging methods have revealed activation of distinct brain areas associated with increased dyspnea. Pulmonary hyperinflation has been proposed to influence the perception of dyspnea. The association of hyperinflation with minor levels of bronchoconstriction reflects the partition of the sensory effect of airway narrowing per se from that of the attendant elastic loading of the inspiratory muscles. There is evidence to suggest, however, that hyperinflation does not play an important role in the pathogenesis of exercise dyspnea as it does during induced bronchoconstriction. Decreased levels of perception of airway obstruction may be a risk factor associated with life-threatening asthma. A poor perceiver may be vulnerable to further hypoxia-induced suppression of respiratory sensation. Monitoring the response to bronchodilator therapy with formoterol and salbutamol in patients with acute or chronic asthma has resulted in significantly faster improvement in dyspnea, within 2 min.

SUMMARY

Regardless of the factors involved, much variability in dyspnea scores remains unexplained. Quantitative and qualitative assessment of the perception of dyspnea, symptom measurement and quality of life complement physiological measurements and contribute to our understanding of dyspnea in asthma.

[Agreement in asthmatics' perception of dyspnea during acute and chronic obstruction]

OBJECTIVE

Three types of asthmatic patients can be identified during periods of clinical stability: "poor perceivers," "normal perceivers," and "over perceivers." When asthmatics undergo bronchial challenge in the laboratory, the same distinctions in type of perception can be observed. The aim of the present study was to determine the level of agreement between the 2 situations.

PATIENTS AND METHODS

A total of 93 patients with persistent moderate asthma (36 men and 57 women; mean age 40 years) were studied. We asked them to assess their dyspnea on a modified Borg scale when stable and after each histamine dose in a bronchial provocation test. When a patient's Borg scale assessment in stable situation was below the 25th percentile, that patient was classified as a poor perceiver. Patients were considered over perceivers if their score in stable situation was in the 75th percentile. Others were labeled normal perceivers. Type of perception during acute bronchoconstriction was defined in function of the change in Borg assessment once forced expiratory volume in the first second had decreased 20%: poor perceivers were those whose change in Borg assessment was in the 25th percentile, over perceivers were in the 75th percentile, and normal perceivers in the middle percentiles.

RESULTS

In stable situation, 23 patients were poor perceivers, 58 were normal perceivers, and 12 were over perceivers. During bronchoconstriction, there were 23 poor perceivers, 47 normal perceivers, and 23 over perceivers. Agreement was estimated by a kappa index of 0.0574 for poor perception, 0.1521 for over perception, and 0.3980 for normal perception.

CONCLUSIONS

Asthmatics' perception of dyspnea during periods of stability and during acute bronchoconstriction are independent phenomena. It is therefore not possible to infer how a patient will perceive an asthmatic attack by evaluating only how he or she perceives breathlessness during stable periods.