Sensory and Affective Aspects of Dyspnea Contribute Differentially to the Borg Scale’s Measurement of Dyspnea

Dificultad respiratoria y COVID-19: Un llamado a la investigación

La dificultad respiratoria, también conocida como disnea, es un síntoma frecuente que causa debilidad. Varios reportes han destacado la ausencia de disnea en un subgrupo de pacientes que padecen COVID-19, en la llamada hipoxemia «silenciosa» o «feliz». Los reportes también han mencionado la falta de una relación clara entre la gravedad clínica de la enfermedad y los niveles de disnea referidos por los pacientes. Se ha demostrado en gran medida que entre las complicaciones cerebrales del COVID-19 hay alta prevalencia de encefalopatía aguda, que podría afectar el procesamiento de las señales aferentes o bien la modulación descendente de las señales de disnea. En esta revisión pretendemos destacar los mecanismos implicados en la disnea y resumir la fisiopatología del COVID-19 y sus efectos en la interacción cerebro-pulmón. Posteriormente, presentamos hipótesis sobre la alteración de la percepción de la disnea en pacientes con COVID-19 y sugerimos formas de investigar más a fondo este fenómeno.

Atemnot und COVID-19: Ein Aufruf zu mehr Forschung

Atemnot, auch als Dyspnoe bezeichnet, ist ein häufiges und lähmendes Symptom. In mehreren Berichten wurde die Abwesenheit von Atemnot bei einer Untergruppe von Patienten mit COVID-19 hervorgehoben, die manchmal als «stille» oder «glückliche Hypoxie» bezeichnet wird. Ebenfalls wurde in Berichten erwähnt, dass es an einem klaren Zusammenhang zwischen dem klinischen Schweregrad der Erkrankung und der von den Patienten berichteten Schwere der Atemnot fehlt. Die zerebralen Komplikationen von COVID-19 sind weitgehend nachgewiesen, mit einer hohen Prävalenz akuter Enzephalopathien, die möglicherweise die Verarbeitung afferenter Signale oder die absteigende Modulation von Atemnotsignalen beeinträchtigen könnte. In dieser Übersichtsarbeit möchten wir die an der Atemnot beteiligten Mechanismen hervorheben und die Pathophysiologie von COVID-19 und den bekannten Auswirkungen der Erkrankung auf die Interaktion von Gehirn und Lunge zusammenfassen. Anschließend stellen wir Hypothesen für die Veränderung der Wahrnehmung von Atemnot bei COVID-19-Patienten auf und schlagen Möglichkeiten vor, mit denen dieses Phänomen weiter erforscht werden könnte.

Dyspnea could be accurately assessed by a caregiver in hospitalized patients with respiratory diseases: Interrater reliability and agreement study

BACKGROUND

The perception of dyspnea is a subjective feeling typically self-assessed by the patient. However, the assessment by a caregiver is sometimes required.

OBJECTIVES

The primary aim was to compare patient self-assessment and caregiver assessment of dyspnea (interrater reliability) using the modified Borg and visual analog scale (VAS) in hospitalized patients. The secondary aim was to compare dyspnea assessment between the two scales for patients and caregiver (inter-instrument reliability).

METHODS

Self-assessment of dyspnea intensity of hospitalized patients with respiratory diseases was compared with caregiver's assessment. Dyspnea intensity was measured using two scales, the modified Borg scale (0-10 scale) and the 10 cm VAS. Mean difference and 95% confidence interval (CI) between assessors (i.e. patient versus caregiver) were calculated for each scale. Inter- and intra-rater reliability was calculated using intraclass correlation coefficients (ICCs).

RESULTS

A total of 254 patients were recruited. The mean differences between patient and caregiver ratings were 0.31 (95% CI: 0.09, 0.53) for the modified Borg scale and 0.36 (95% CI: 0.06, 0.65) for the VAS scale. Interrater reliability was good for both scales with ICC of 0.79 (95% CI: 0.73, 0.84) for VAS and 0.82 (95% CI: 0.77, 0.86) for the modified Borg scale. The mean differences in scores between scales were 0.93 (95% CI 0.69, 1.17) for patients' ratings and 0.88 (95% CI 0.72, 1.04) for caregiver's rating. The inter-instrument reliability was moderate to good and similar for both assessors.

CONCLUSION

Dyspnea can be accurately estimated by caregivers when patients with lung diseases cannot self-report. Scores on the VAS to rate dyspnea were higher than the scores on the Borg scale.

Breathlessness and COVID-19: A Call for Research

Breathlessness, also known as dyspnoea, is a debilitating and frequent symptom. Several reports have highlighted the lack of dyspnoea in a subgroup of patients suffering from COVID-19, sometimes referred to as “silent” or “happy hyp­oxaemia.” Reports have also mentioned the absence of a clear relationship between the clinical severity of the disease and levels of breathlessness reported by patients. The cerebral complications of COVID-19 have been largely demonstrated with a high prevalence of an acute encephalopathy that could possibly affect the processing of afferent signals or top-down modulation of breathlessness signals. In this review, we aim to highlight the mechanisms involved in breathlessness and summarize the pathophysiology of COVID-19 and its known effects on the brain-lung interaction. We then offer hypotheses for the alteration of breathlessness perception in COVID-19 patients and suggest ways of further researching this phenomenon.

Multidimensional breathlessness response to exercise: Impact of COPD and healthy ageing

This study compared the multidimensional breathlessness response to incremental cardiopulmonary cycle exercise testing (CPET) in people with chronic obstructive pulmonary disease (COPD; n = 14, aged 69 ± 9 years, forced expiratory volume in 1-sec = 54 ± 16 % predicted) and healthy older (OA) (n = 35, aged 68 ± 5 years) and younger (YA) (n = 19, aged 28 ± 8 years) adults. Participants performed CPET and successively rated overall breathlessness intensity, unsatisfied inspiration, breathing too shallow, work/effort of breathing, and breathlessness-related unpleasantness, fear, and anxiety using the 0-10 Borg scale. At any given percent predicted peak minute ventilation, people with COPD rated all breathlessness sensations higher than OA and YAs, who were similar. Most between group differences disappeared when examined in relation to inspiratory reserve volume, except people with COPD reported higher levels of unsatisfied inspiration and breathing too shallow (vs YA), and breathlessness-related fear and anxiety (vs OA and YAs). Multidimensional ratings of breathlessness sensations during CPET provides further insight into differences in exertional symptom perceptions among people with COPD and without COPD.

The Effects of Repeated Dyspnea Exposure on Response Inhibition

In order to treat dyspnea (=breathlessness) successfully, response inhibition (RI) as a major form of self-regulation is a premise. This is supported by research showing that self-regulation is associated with beneficial behavioral changes supporting treatment success in patients. Recent research showed that dyspnea has an impairing effect on RI, but the effects of repeated dyspnea exposure on RI remain unknown. Therefore, the present study tested the effects of repeated resistive load-induced dyspnea on RI over a 5-day period. Healthy volunteers (n = 34) performed the standard version of the Stroop task during baseline and dyspnea conditions on the first and fifth testing day and underwent an additional dyspnea exposure phase on each testing day. Variables of interest to investigate RI were reaction time, accuracy as well as the event-related potentials late positive complex (LPC) and N400 in the electroencephalogram. Reduced accuracy for incongruent compared to congruent stimuli during the dyspnea condition on the first testing day were found (p < 0.001). This was paralleled by a reduced LPC and an increased N400 for incongruent stimuli during the induction of dyspnea (p < 0.05). After undergoing dyspnea exposure, habituation of dyspnea intensity was evident. Importantly, on the fifth testing day, no differences between baseline, and dyspnea conditions were found for behavioral and electrophysiological measures of RI. These findings demonstrate that the impairing effect of dyspnea on RI disappeared after repeated dyspnea exposure in healthy participants. Translated to a clinical sample, it might cautiously be suggested that dyspnea exposure such as dyspnea perceived during physical exercise could reduce the impairing effect of dyspnea on RI which might have the potential to help increase self-regulation abilities and subsequent treatment efforts in dyspneic patients.

A Bayesian network meta-analysis on the efficacy and safety of eighteen targeted drugs or drug combinations for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) can be relieved by pharmacological interventions, especially the targeted drug, which is classified into endothelin receptor antagonist, phosphodiesterase 5 inhibitor, prostaglandin I₂, soluble guanylate cyclase stimulator and selective non-prostanoid prostacyclin receptor agonist. To solve the contradictions existing in reported trials and provide a comprehensive guideline for clinical practice. PubMed, Embase, Cochrane library, and clinicaltrials.gov were searched. The basic information about the article, trial, arm, intervention, and the detailed data of outcome, including 6 minutes walking distance (6MWD) change, WHO functional class (FC) improvement, Borg dyspnea score (BDS) change, cardiac index (CI) change, mean pulmonary arterial pressure (mPAP) change, mean right arterial pressure (mRAP) change, pulmonary vascular resistance (PVR) change, clinical worsening, hospitalization, death, severe adverse events (SAEs), and withdrawal were extracted. The rank of treatments was estimated. 10,230 cases provided the firsthand comparison data about targeted drugs for treating PAH. For 6MWD, ambrisentan + tadalafil, vardenafil, and sildenafil + bosentan were better than others. Epoprostenol, macitentan, and sildenafil represented a greater WHO FC improvement. Vardenafil and treprostinil were better for BDS. So were bosentan + epoprostenol and bosentan alone for CI. Iloprost plus bosentan, bosentan + epoprostenol, and epoprostenol were better for mPAP. Iloprost plus bosentan, bosentan alone, and selexipag could reduce PVR. Sildenafil, epoprostenol, and vardenafil had the highest probability to reduce the incidence of death and withdrawal. To conclude, vardenafil and iloprost + bosentan showed relatively better performance in both efficacy and safety. However, the therapeutic choice should be made according to both the feature of each therapy and the individual condition.

The Impact of Listening to Music During a High-Intensity Exercise Endurance Test in People With COPD

BACKGROUND

In people with COPD, dyspnea is the primary symptom limiting exercise tolerance. One approach to reducing dyspnea during exercise is through music listening. A constant speed endurance test reflects a high-intensity aerobic exercise training session, but whether listening to music affects endurance time is unknown. This study aimed to determine the effects of listening to music during a constant speed endurance test in COPD.

METHODS

Participants with COPD completed two endurance walk tests, one with and one without listening to self-selected music throughout the test. The primary outcome was the difference in endurance time between the two conditions. Heart rate, percutaneous oxygen saturation, dyspnea, and rate of perceived exertion were measured before and after each test.

RESULTS

Nineteen participants (mean [SD]: age, 71 [8] years; FEV₁, 47 [19] % predicted) completed the study. Endurance time was greater (1.10 [95% CI, 0.41-1.78] min) while listening to music (7.0 [3.1] min) than without (5.9 [2.6] min), and reduced end-test dyspnea (1.0 [95% CI, -2.80 to -1.80] units) (with music, 4.6 [1.7] units; vs without music, 5.6 [1.4] units, respectively). There was not a significant difference in heart rate, percutaneous oxygen saturation, or leg fatigue. There were no adverse events under either condition.

CONCLUSIONS

In COPD, dyspnea was less while listening to music and was accompanied by an increased tolerance of high-intensity exercise demonstrated by greater endurance time. Practically, the effect was modest but may represent an aid for exercise training of these patients.

TRIAL REGISTRY

Australian New Zealand Clinical Trials Registry; No. ACTRN12617001217392.

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.

Relationship between the sensation of activity limitation and the results of functional assessment in asthma patients

OBJECTIVE

In asthma patients, the assessment of activity limitation is based on questions evaluating how limited the patient feels in their activities. However, the lack of functional data complicates the interpretation of the answers. We aimed to evaluate the intensity of relationships between the patient's perception of activity limitation and the results of several functional tests.

METHODS

Twenty patients complaining of asthma exacerbation were invited to complete three scores (Chronic Respiratory Disease questionnaire, Asthma Control Questionnaire, Hospital Anxiety and Depression scale). They also underwent lung function measurements, a 6-minute walk test and a cardio-pulmonary exercise test. In addition, physical activity was studied by actigraphy. Spearman's rank correlation coefficients between the patient's perception of activity limitation and each of the other parameters were analysed.

RESULTS

Five parameters were significantly correlated with the perception of activity limitation: ACQ question 4, related to dyspnea (rs 0.74, p < 0.001); Emotion domain of the Chronic Respiratory Disease questionnaire (rs -0.57, p = 0.02); HAD anxiety (rs 0.48, p = 0.032); HAD depression (rs 0.46, p = 0.041); ACQ question 6, related to reliever use (rs 0.46, p = 0.046). No parameters from the lung function test, 6MWT, CPET or actigraphy, were significantly correlated with the perception of activity limitation.

CONCLUSIONS

In response to questions about limitation of activity, patients do not specifically answer mentioning physical limitation but rather the psychological burden associated with this constraint.

A randomised controlled trial of three or one breathing technique training sessions for breathlessness in people with malignant lung disease

BACKGROUND

About 90 % of patients with intra-thoracic malignancy experience breathlessness. Breathing training is helpful, but it is unknown whether repeated sessions are needed. The present study aims to test whether three sessions are better than one for breathlessness in this population.

METHODS

This is a multi-centre randomised controlled non-blinded parallel arm trial. Participants were allocated to three sessions or single (1:2 ratio) using central computer-generated block randomisation by an independent Trials Unit and stratified for centre. The setting was respiratory, oncology or palliative care clinics at eight UK centres. Inclusion criteria were people with intrathoracic cancer and refractory breathlessness, expected prognosis ≥3 months, and no prior experience of breathing training. The trial intervention was a complex breathlessness intervention (breathing training, anxiety management, relaxation, pacing, and prioritisation) delivered over three hour-long sessions at weekly intervals, or during a single hour-long session. The main primary outcome was worst breathlessness over the previous 24 hours ('worst'), by numerical rating scale (0 = none; 10 = worst imaginable). Our primary analysis was area under the curve (AUC) 'worst' from baseline to 4 weeks. All analyses were by intention to treat.

RESULTS

Between April 2011 and October 2013, 156 consenting participants were randomised (52 three; 104 single). Overall, the 'worst' score reduced from 6.81 (SD, 1.89) to 5.84 (2.39). Primary analysis [n = 124 (79 %)], showed no between-arm difference in the AUC: three sessions 22.86 (7.12) vs single session 22.58 (7.10); P value = 0.83); mean difference 0.2, 95 % CIs (-2.31 to 2.97). Complete case analysis showed a non-significant reduction in QALYs with three sessions (mean difference -0.006, 95 % CIs -0.018 to 0.006). Sensitivity analyses found similar results. The probability of the single session being cost-effective (threshold value of £20,000 per QALY) was over 80 %.

CONCLUSIONS

There was no evidence that three sessions conferred additional benefits, including cost-effectiveness, over one. A single session of breathing training seems appropriate and minimises patient burden.

TRIAL REGISTRATION

Registry: ISRCTN;

TRIAL REGISTRATION NUMBER

ISRCTN49387307; http://www.isrctn.com/ISRCTN49387307 ; registration date: 25/01/2011.

Effect of anticipation triggered by a prior dyspnea experience on brain activity

[Purpose] Oxygenated hemoglobin (oxy-Hb) concentrations in the prefrontal cortex are closely associated with dyspnea. Dyspnea is influenced not only by physical activity, but also by visual stimuli, and several studies suggest that oxy-Hb concentrations change in response to certain external stimuli. However, the effects of internal psychological states on dyspnea have not been reported. This study explored the influence of anticipation triggered by previous episodes of dyspnea on brain activity. [Subjects] The subjects were 15 healthy volunteers with a mean age of 25.0 ± 3.0 years. [Methods] The subjects were shown a variety of photographs and instructed to expect breathing resistance matched to the affective nature of the particular photograph. After viewing the images, varying intensities of breathing resistance that were identical to, easier than, or harder than those shown in the images were randomly administered to the subjects; in fact, the image and resistance were identical 33% of the time and discordant 66% of the time. [Results] The concentrations of oxy-Hb in the right medial prefrontal cortex (rMPFC) increased significantly with an inspiratory pressure that was 30% of the maximum intensity in the subjects shown a pleasant image compared to the concentrations in subjects shown an unpleasant image. Moreover, rMPFC activity was significantly correlated with the magnitude of the dyspnea experienced. [Conclusion] These results suggest that a correlation exists between increased oxy-Hb in the rMPFC and the effects of expectations on dyspnea.

Variability of the perception of dyspnea in healthy subjects assessed through inspiratory resistive loading

Objective:

Few studies have evaluated the variability of the perception of dyspnea in healthy subjects. The objective of this study was to evaluate the variability of the perception of dyspnea in healthy subjects during breathing against increasing inspiratory resistive loads, as well as to assess the association between the level of perception of dyspnea and the level of physical activity.

Methods:

This was a cross-sectional study involving healthy individuals 16 years of age or older. Subjects underwent inspiratory resistive loading testing, in which the level of perception of dyspnea was quantified with the modified Borg scale. We also determined body mass indices (BMIs), assessed maximal respiratory pressures, performed pulmonary function tests, applied the international physical activity questionnaire (IPAQ)-long form, and conducted six-minute walk tests (6MWTs). The level of perception of dyspnea was classified as low (Borg score < 2), intermediate (Borg score, 2-5), or high (Borg score > 5).

Results:

We included 48 healthy subjects in the study. Forty-two subjects completed the test up to a load of 46.7 cmH₂O/L/s. The level of perception of dyspnea was classified as low, intermediate, and high in 13, 19, and 10 subjects, respectively. The level of perception of dyspnea was not significantly associated with age, gender, BMI, IPAQ-long form score, maximal respiratory pressures, or pulmonary function test results.

Conclusions:

The scores for perceived dyspnea induced by inspiratory resistive loading in healthy subjects presented wide variability. The perception of dyspnea was classified as low in 31% of the subjects, intermediate in 45%, and high in 24%. There was no association between the level of perception of dyspnea and the level of physical activity (IPAQ or six-minute walk distance).

Repeatability of the evaluation of perception of dyspnea in normal subjects assessed through inspiratory resistive loads

Purpose:

Study the repeatability of the evaluation of the perception of dyspnea using an inspiratory resistive loading system in healthy subjects.

Methods:

We designed a cross sectional study conducted in individuals aged 18 years and older. Perception of dyspnea was assessed using an inspiratory resistive load system. Dyspnea was assessed during ventilation at rest and at increasing resistive loads (0.6, 6.7, 15, 25, 46.7, 67, 78 and returning to 0.6 cm H2O/L/s). After breathing in at each level of resistive load for two minutes, the subject rated the dyspnea using the Borg scale. Subjects were tested twice (intervals from 2 to 7 days).

Results:

Testing included 16 Caucasian individuals (8 male and 8 female, mean age: 36 years). The median scores for dyspnea rating in the first test were 0 at resting ventilation and 0, 2, 3, 4, 5, 7, 7 and 1 point, respectively, with increasing loads. The median scores in the second test were 0 at resting and 0, 0, 2, 2, 3, 4, 4 and 0.5 points, respectively. The intra-class correlation coefficient was 0.57, 0.80, 0.74, 0.80, 0.83, 0.86, 0.91, and 0.92 for each resistive load, respectively. In a generalized linear model analysis, there was a statistically significant difference between the levels of resistive loads (p<0.001) and between tests (p=0.003). Dyspnea scores were significantly lower in the second test.

Conclusion:

The agreement between the two tests of the perception of dyspnea was only moderate and dyspnea scores were lower in the second test. These findings suggest a learning effect or an effect that could be at least partly attributed to desensitization of dyspnea sensation in the brain.

Sedation in non-invasive ventilation: do we know what to do (and why)?

This review examines some of the issues encountered in the use of sedation in patients receiving respiratory support from non-invasive ventilation (NIV). This is an area of critical and intensive care medicine where there are limited (if any) robust data to guide the development of best practice and where local custom appears to exert a strong influence on patterns of care.

We examine aspects of sedation for NIV where the current lack of structure may be contributing to missed opportunities to improve standards of care and examine the existing sedative armamentarium. No single sedative agent is currently available that fulfils the criteria for an ideal agent but we offer some observations on the relative merits of different agents as they relate to considerations such as effects on respiratory drive and timing, and airways patency. The significance of agitation and delirium and the affective aspect(s) of dyspnoea are also considered.

We outline an agenda for placing the use of sedation in NIV on a more systematic footing, including clearly expressed criteria and conditions for terminating NIV and structural and organizational conditions for prospective multicentre trials.

The affective dimension of dyspnea improves in a dyspnea self-management program with exercise training

CONTEXT

The perception of dyspnea includes both sensory and affective dimensions that are shaped by emotions and psychological, social, and environmental experiences. Previous investigators have studied either measurement or strategies to decrease the affective dimension with laboratory-induced dyspnea. Few have reported the effect of a therapeutic clinical intervention on the affective dimension of dyspnea.

OBJECTIVES

(1) To evaluate the effects of three different versions of a dyspnea self-management program (DM) on the affective dimension of dyspnea, measured by dyspnea-related anxiety (DA) and dyspnea-related distress (DD); and (2) to determine the stability of DA and DD over two baseline incremental treadmill tests (ITTs).

METHODS

Participants with chronic obstructive pulmonary disease were randomly assigned to three 12 month DMs with varying doses of supervised exercise (DM, DM-Exposure, and DM-Training). The measurements of the affective dimension, DA and DD, were rated during ITTs on two baseline days and at two, six, and 12 months. Changes over time in DA and DD were analyzed using linear mixed-effects models.

RESULTS

Participants in the DM-Training group who received 24 nurse-coached exercise sessions had significantly greater reductions in DA and DD compared with those who had four exercise sessions (DM-Exposure) or only received a home-walking program (DM). Reductions in DA and DD in the DM-Training group were only maintained through six months. There were no significant differences in ratings of DA and DD at end between the two baseline ITTs.

CONCLUSION

These findings provide initial support for the positive impact of a self-management program with nurse-coached exercise on the affective dimension of dyspnea. Further investigation of interventions that target the affective dimension in addition to the sensory dimension of dyspnea should be encouraged.

Evidence for cognitive-behavioral strategies improving dyspnea and related distress in COPD

BACKGROUND

Dyspnea is a complex, prevalent, and distressing symptom of chronic obstructive pulmonary disease (COPD) associated with decreased quality of life, significant disability, and increased mortality. It is a major reason for referral to pulmonary rehabilitation.

METHODS

We reviewed 23 COPD studies to examine the evidence for the effectiveness of cognitive-behavioral strategies for relieving dyspnea in COPD.

RESULTS

Preliminary evidence from randomized controlled trials exists to support cognitive- behavioral strategies, used with or without exercise, for relieving sensory and affective components of dyspnea in COPD. Small to moderate treatment effects for relieving dyspnea were noted for psychotherapy (effect size [ES] = 0.08-0.25 for intensity; 0.26-0.65 for mastery) and distractive auditory stimuli (ES = 0.08-0.33 for intensity; 0.09 to -0.61 for functional burden). Small to large dyspnea improvements resulted from yoga (ES = 0.2-1.21 for intensity; 0.67 for distress; 0.07 for mastery; and -8.37 for functional burden); dyspnea self-management education with exercise (ES = -0.14 to -1.15 for intensity; -0.62 to -0.69 for distress; 1.04 for mastery; 0.14-0.35 for self-efficacy); and slow-breathing exercises (ES = -0.34 to -0.83 for intensity; -0.61 to -0.80 for distress; and 0.62 for self-efficacy). Cognitive-behavioral interventions may relieve dyspnea in COPD by (1) decreasing sympathetic nerve activity, dynamic hyperinflation, and comorbid anxiety, and (2) promoting arterial oxygen saturation, myelinated vagus nerve activity, a greater exercise training effect, and neuroplasticity.

CONCLUSION

While evidence is increasing, additional randomized controlled trials are needed to evaluate the effectiveness of psychosocial and self-management interventions in relieving dyspnea, in order to make them more available to patients and to endorse them in official COPD, dyspnea, and pulmonary rehabilitation practice guidelines. By relieving dyspnea and related anxiety, such interventions may promote adherence to exercise programs and adaptive lifestyle change.

Dyspnea perception in cystic fibrosis patients

We evaluated dyspnea perception in cystic fibrosis patients compared with normal subjects, during an inspiratory resistive loading test and 6-min walk test. We also evaluated the correlation between dyspnea scores induced by resistive loads and by the 6-min walk test. In this prospective, cross-sectional study, 31 patients with cystic fibrosis (≥15 years of age) and 31 age-, gender-, and ethnicity-matched healthy volunteers (20 females and 11 males per group) underwent inspiratory resistive loading, spirometry, and the 6-min walk test. As the magnitude of the inspiratory loads increased, dyspnea scores increased (P<0.001), but there was no difference between groups in dyspnea score (P=0.654). Twenty-six (84%) normal subjects completed all the resistive loads, compared with only 12 (39%) cystic fibrosis patients (P<0.001). Dyspnea scores were higher after the 6-min walk test than at rest (P<0.001), but did not differ between groups (P=0.080). Post-6-min walk test dyspnea scores correlated significantly with dyspnea scores induced by resistive loads. We conclude that dyspnea perception induced in cystic fibrosis patients by inspiratory resistive loading and by 6-min walk test did not differ from that induced in normal subjects. However, cystic fibrosis patients discontinued inspiratory resistive loading more frequently. There were significant correlations between dyspnea perception scores induced by inspiratory resistance loading and by the 6-min walk test. This study should alert clinicians to the fact that some cystic fibrosis patients fail to discriminate dyspnea perception and could be at risk for delay in seeking medical care.

The longitudinal pattern of response when morphine is used to treat chronic refractory dyspnea

BACKGROUND

While evidence supports using sustained release morphine for chronic refractory breathlessness, little is known about the longitudinal pattern of breathlessness intensity as people achieve symptomatic benefit. The aim of this study is to describe this pattern.

METHODS

This secondary analysis used breathlessness intensity scores (100 mm visual analogue scale (VAS)) from a prospective, dose increment study of once daily (morning) sustained release morphine for chronic refractory breathlessness. Participants who achieved <10% improvement over their own baseline at one week (10 mg) were titrated to 20 mg and if no response, another week later to 30 mg for one week. Time was standardized at the first day of the week in which participants responded generating twice daily data one week either side of symptomatic benefit. Analysis used random effect mixed modeling.

RESULTS

Of the 83 participants, 17/52 responders required >10 mg: 13 participants (20 mg) and 4 (30 mg), contributing 634 VAS observations. In the week leading to a response, average VAS scores worsened by 0.3 mm/day (p=0.16); the average improvement in the first 24 hours of response was 10.9 mm (7.0 to 14.7; p<0.0001), with continued improvement of 2.2 mm/day (p<0.001) for six more days.

CONCLUSION

When treating chronic refractory breathlessness with once daily sustained release morphine, titrate to effect, since inadequate dose may generate no response; and following an initial response, further dose increases should not occur for at least one week. Whether further benefit would be derived beyond day six on the dose to which people respond, and what net effect a further dose increase would have are questions yet to be answered.

A multidimensional computer adaptive test approach to dyspnea assessment

OBJECTIVES

To develop and test a prototype dyspnea computer adaptive test (CAT).

DESIGN

Prospective study.

SETTING

Two outpatient medical facilities.

PARTICIPANTS

A convenience sample of adults (N=292) with chronic obstructive pulmonary disease (COPD).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

We developed a modified and expanded item bank and CAT for the Dyspnea Management Questionnaire (DMQ), an outcome measure consisting of 4 dyspnea dimensions: dyspnea intensity, dyspnea anxiety, activity avoidance, and activity self-efficacy.

RESULTS

Factor analyses supported a 4-dimensional model underlying the 71 DMQ items. The DMQ item bank achieved acceptable Rasch model fit statistics, good measurement breadth with minimal floor and ceiling effects, and evidence of high internal consistency reliability (α=.92-.98). With the use of CAT simulation analyses, the DMQ-CAT showed high measurement accuracy compared with the total item pool (r=.83-.97, P<.0001) and evidence of good to excellent concurrent validity (r=-.61 to -.80, P<.0001). All DMQ-CAT domains showed evidence for known-groups validity (P≤.001).

CONCLUSIONS

The DMQ-CAT reliably and validly captured 4 distinct dyspnea domains. Multidimensional dyspnea assessment in COPD is needed to better measure the effectiveness of pharmacologic, pulmonary rehabilitation, and psychosocial interventions in not only alleviating the somatic sensation of dyspnea but also reducing dysfunctional emotions, cognitions, and behaviors associated with dyspnea, especially for anxious patients.

Effects of low-level laser therapy (808 nm) on isokinetic muscle performance of young women submitted to endurance training: a randomized controlled clinical trial

Low-level laser therapy (LLLT) has shown efficacy in muscle bioenergetic activation and its effects could influence the mechanical performance of this tissue during physical exercise. This study tested whether endurance training associated with LLLT could increase human muscle performance in isokinetic dynamometry when compared to the same training without LLLT. The primary objective was to determine the fatigue index of the knee extensor muscles (FIext) and the secondary objective was to determine the total work of the knee extensor muscles (TWext). Included in the study were 45 clinically healthy women (21 ± 1.78 years old) who were randomly distributed into three groups: CG (control group), TG (training group) and TLG (training with LLLT group). The training for the TG and TLG groups involved cycle ergometer exercise with load applied to the ventilatory threshold (VT) for 9 consecutive weeks. Immediately after each training session, LLLT was applied to the femoral quadriceps muscle of both lower limbs of the TLG subjects using an infrared laser device (808 nm) with six 60-mW diodes with an energy of 0.6 J per diode and a total energy applied to each limb of 18 J. VT was determined by ergospirometry during an incremental exercise test and muscle performance was evaluated using an isokinetic dynamometer at 240°/s. Only the TLG showed a decrease in FIext in the nondominant lower limb (P = 0.016) and the dominant lower limb (P = 0.006). Both the TLG and the TG showed an increase in TWext in the nondominant lower limb (P < 0.001 and P = 0.011, respectively) and in the dominant lower limb (P < 0.000 and P < 0.000, respectively). The CG showed no reduction in FIext or TWext in either lower limb. The results suggest that an endurance training program combined with LLLT leads to a greater reduction in fatigue than an endurance training program without LLLT. This is relevant to everyone involved in sport and rehabilitation.

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.

Perception of multiple-breath inspiratory resistive loads in males and females

Resistive load magnitude estimation (ME) was measured over multiple breaths in male and female subjects. It was hypothesized that multiple breaths against a range of resistive loads would result in a change in the perceived load magnitude as a function of load magnitude and the number of inspiratory efforts. It was further hypothesized that males and females would differ in their perceptual response to sustained breathing against inspiratory resistive loads. The subjects were tested in a sound isolated room and respired through a non-rebreathing valve, the inspiratory port connected to the loading manifold. The subject inspired to a peak airflow target for each breath. Each R load was presented for 10 continuous breaths. The load was estimated at breath 1, 5, and 10 using a modified Borg scale. Each 10-breath load presentation was presented in a randomized block. There was no significant group difference between the ME for breath 1 and 10 for small R loads, but a significant group difference for large R loads. The ME for males did not change between breath 1 and 10 for the small load magnitudes, but decreased with large loads. The ME for the 10th breath of the large R load was greater than the 1st breath for females. Males estimated the large R load on the 1st breath the same as females but the ME on the 10th breath was significantly less for males compared to females. These results demonstrate that magnitude estimation of large resistive loads with a sustained 10-breath trial elicits significant increases in females, but significantly decreased in males. The increase in ME may represent increased respiratory discomfort for females and the decrease habituation in males.

Anxiety is associated with diminished exercise performance and quality of life in severe emphysema: a cross-sectional study

Background

Anxiety in patients with chronic obstructive pulmonary disease (COPD) is associated with self-reported disability. The purpose of this study is to determine whether there is an association between anxiety and functional measures, quality of life and dyspnea.

Methods

Data from 1828 patients with moderate to severe emphysema enrolled in the National Emphysema Treatment Trial (NETT), collected prior to rehabilitation and randomization, were used in linear regression models to test the association between anxiety symptoms, measured by the Spielberger State Trait Anxiety Inventory (STAI) and: (a) six-minute walk distance test (6 MWD), (b) cycle ergometry peak workload, (c) St. Georges Respiratory Questionnaire (SRGQ), and (d) UCSD Shortness of Breath Questionnaire (SOBQ), after controlling for potential confounders including age, gender, FEV₁ (% predicted), DL_CO (% predicted), and the Beck Depression Inventory (BDI).

Results

Anxiety was significantly associated with worse functional capacity [6 MWD (B = -0.944, p < .001), ergometry peak workload (B = -.087, p = .04)], quality of life (B = .172, p < .001) and shortness of breath (B = .180, p < .001). Regression coefficients show that a 10 point increase in anxiety score is associated with a mean decrease in 6 MWD of 9 meters, a 1 Watt decrease in peak exercise workload, and an increase of almost 2 points on both the SGRQ and SOBQ.

Conclusion

In clinically stable patients with moderate to severe emphysema, anxiety is associated with worse exercise performance, quality of life and shortness of breath, after accounting for the influence of demographic and physiologic factors known to affect these outcomes.

Trail Registration

ClinicalTrials.gov NCT00000606

The impact of panic disorder on interoception and dyspnea reports in chronic obstructive pulmonary disease

The prevalence of panic disorder (PD) in patients with chronic obstructive pulmonary disease (COPD) is significantly higher than that in the general population. Comorbid anxiety disorders in COPD are associated with a number of worse outcomes, however little is known about the mechanisms by which PD affects patients with COPD. We hypothesized that patients with COPD and PD would have greater dyspnea severity, but not greater somatosensory sensitivity, to dyspneic stimuli. We studied 10 patients with COPD and PD, 9 patients with COPD without PD, and 9 healthy, matched controls. Participants were administered the Anxiety Sensitivity Index-3. We tested interoceptive sensitivity using a respiratory load detection protocol and dyspnea ratings in response to inspiratory resistive loads. Participants with COPD and PD had higher anxiety sensitivity scores and reported greater dyspnea in response to resistive loads. However no group differences were found in resistive load detection threshold. Anxiety sensitivity scores accounted for a significant amount of the variance in the group difference in dyspnea ratings. Patients with COPD and PD do not show heightened interoceptive sensitivity, but report greater dyspnea to inspiratory resistive loads. Emotional responses to dyspneic sensations may account for higher dyspnea ratings in patients with PD and COPD.

Additional evidence for the affective dimension of dyspnea in patients with COPD

The primary purpose of this secondary analysis was to determine whether 103 participants with chronic obstructive pulmonary disease rated the affective dimension of dyspnea (dyspnea-related anxiety and dyspnea-related distress) separately from the sensory dimension (intensity) during baseline exercise testing conducted as part of a randomized clinical trial. A secondary purpose was to determine if dyspnea-related anxiety and distress were rated distinctly different from other measurements of anxiety. At the end of a 6-minute walk and an incremental treadmill test, participant ratings of the magnitude of dyspnea-related anxiety and distress on the Modified Borg Scale were significantly different from their ratings of the intensity of dyspnea. Dyspnea-related anxiety and distress also appeared to be concepts independent from measures of state anxiety, negative affect, and anxiety before a treadmill test.

Quality of recalled dyspnoea is different from exercise-induced dyspnoea: an experimental study

QUESTIONS

Are volunteered and endorsed descriptors of recalled breathlessness consistent with descriptors of exercise-induced breathlessness? Are volunteered and endorsed descriptors of exercise-induced breathlessness consistent?

DESIGN

Within-participant, repeated measures, experimental study.

PARTICIPANTS

57 people with symptomatic chronic respiratory disease aged 71 years.

INTERVENTION

There were three conditions. The first was recalled breathlessness. Two conditions of exercise-induced breathlessness were created by getting the participants to undertake the 6-min Walk Test twice (breathlessness 1 and 2).

OUTCOME MEASURES

Descriptors of breathlessness were volunteered (where participants' used their own words) or endorsed (from a pre-existing list of 15 breathlessness statements).

RESULTS

Emotive descriptors made up 65% of recalled descriptors compared with 11% of exercise-induced descriptors, whereas physical descriptors made up 35% of recalled descriptors compared with 89% of exercise-induced descriptors. Of the 237 potential language pairs volunteered to describe recalled and exercise-induced breathlessness 1, only 27 (11%) were identical whereas of the 171 potential language pairs endorsed as describing recalled and exercise-induced breathlessness 1, 66 (39%) were identical. Of the 175 potential language pairs of descriptors volunteered to describe exercise-induced breathlessness 1 and 2, 72 (41%) were identical whereas of the 153 potential language pairs endorsed as describing exercise-induced breathlessness 1 and 2, 71 (46%) were identical.

CONCLUSION

The language used to describe exercise-induced breathlessness immediately after two walking challenges was similar. However, descriptions of recalled breathlessness did not consistently match descriptions of exercise-induced breathlessness, which may reflect the different contexts under which breathlessness was recalled and induced.

The impact of affective states on the perception of dyspnea in patients with chronic obstructive pulmonary disease

Dyspnea is the cardinal symptom of chronic obstructive pulmonary disease (COPD). Affective states can profoundly impact upon the perception of dyspnea, but little is known about this relationship in patients with COPD. We, therefore, examined the impact of viewing positive versus negative affective picture series on perceived dyspnea during two cycle ergometer exercise tests (CEET) in 30 patients with COPD. Whereas cardiopulmonary measures indicated comparable exercise intensity during both CEETs, parallel viewing of negative affective pictures resulted in increased dyspnea ratings compared to positive affective pictures. Regression analyses showed that only during positive picture viewing increases in the affective unpleasantness of dyspnea, but not in the sensory intensity of dyspnea, during CEETs were predictive of greater dyspnea during everyday activities and reduced health-related quality of life. The results suggest that negative affective states increase perceived dyspnea in patients with COPD and underline the importance of targeting the affect-dyspnea-relationship in this patient group.

Repeated breathlessness experiences induced by hypercapnia: differential effects on intensity and unpleasantness

BACKGROUND

The present study investigated the effect of repeated hypercapnic challenges on the sensory (intensity [I]) and affective (unpleasantness [U]) dimensions of breathlessness.

METHODS

Three subsequent rebreathing trials (Read, 1968) were administered to healthy men and women (n = 39). The I and U of breathlessness were rated every 20 s during the baseline, rebreathing, and recovery phases. Breathing behavior (fractional end-tidal CO(2) [Fetco(2)] and minute ventilation [Ve]) was monitored continuously. Intraindividual linear regression slopes for Fetco(2) and Ve] were calculated and standardized, separately for both rating dimensions.

RESULTS

Both the absolute magnitude and the slope of the I of breathlessness were higher compared to U (p < 0.05). Across-trial habituation of the peak I and U of breathlessness occurred in both genders (p < 0.001), but habituation was larger for the U than for the I (p = 0.05).

CONCLUSIONS

The findings show that the sensory and affective dimensions of breathlessness can meaningfully be distinguished during hypercapnic challenges and that repeated exposures have different effects on both dimensions.

Mechanisms of dyspnea in chronic lung disease

PURPOSE OF REVIEW

To discuss three emerging areas of research triggering new hypotheses for mechanisms of dyspnea.

RECENT FINDINGS

There has been an emphasis on the importance of lung volumes in evaluating symptoms and lung function in patients with chronic obstructive pulmonary disease. Dyspnea intensity seems to more closely correlate with measures of hyperinflation than airflow limitation, highlighting the importance of neuromechanical dissociation in the development of dyspnea. Inhaled furosemide has demonstrated a beneficial effect in laboratory-induced dyspnea, and the sensation of air hunger has been ameliorated by this therapy, possibly via activation of pulmonary stretch receptors. There appear to be distinct affective and sensory components of dyspnea, and the affective dimension may be modifiable, although this has not been fully studied.

SUMMARY

Dyspnea in chronic obstructive pulmonary disease is clearly related to hyperinflation, and lung volumes are valuable for characterizing disease. It remains unclear whether a limitation in tidal volume due to dynamic hyperinflation is the key factor in exertional dyspnea in this disease. Research of inhaled furosemide demonstrates the importance of afferent sensory input in modifying dyspnea, and deserves further study. The contributions of the affective and sensory components of dyspnea remain unclear, but should be studied further.

Reduced perception of dyspnea and pain after right insular cortex lesions

RATIONALE

The perception of dyspnea and pain show many similarities. Initial imaging studies suggested an important role of the insular cortex for the perception of both sensations. However, little is known about the cortical processing of dyspnea.

OBJECTIVES

This study investigated the influence of lesions of the insular cortex on the perception of dyspnea and pain.

METHODS

Dyspnea was induced by resistive loaded breathing in four patients with right-hemispheric insular cortex lesions, as assessed with computer tomography or magnetic resonance imaging, and four matched healthy control subjects. Pain was induced by a cold-pressor test. Perceived intensity and unpleasantness of both sensations were rated on visual analog scales.

MEASUREMENTS AND MAIN RESULTS

In contrast to healthy control subjects, patients with lesions demonstrated reduced perceptual sensitivity for dyspnea, in particular for the unpleasantness of dyspnea (P < 0.05). This was paralleled by reduced sensitivity for pain in patients with lesions, as reflected by smaller ratings of intensity and unpleasantness, higher sensory pain-thresholds, and, in particular, higher affect-related pain tolerance times (P < 0.05).

CONCLUSIONS

The results suggest that lesions of the right insular cortex are associated with reduced sensitivity for the perception of dyspnea and pain, in particular for their perceived unpleasantness. This underlines the importance of the insular cortex for the perception of both sensations.

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.

The language of breathlessness differentiates between patients with COPD and age-matched adults

BACKGROUND

If descriptors of the sensation of breathlessness are able to differentiate between medical conditions, the language of breathlessness could potentially have a role in differential diagnosis. This study investigated whether the language used to describe the sensation of breathlessness accurately categorized older individuals with and without a prior diagnosis of COPD.

METHODS

Using a parallel-group design, participants with and without a prior diagnosis of COPD volunteered words and phrases and endorsed up to three statements to describe their sensation of breathlessness. Cluster analysis (v-fold cross-validation) was applied, and subjects were clustered by their choice of words. Cluster membership was then compared to original group membership (COPD vs non-COPD), and predictive power was assessed.

RESULTS

Groups were similar for age and gender (COPD, n = 94; 48 men; mean age, 70 +/- 10 years [+/- SD]; vs non-COPD, n = 55; 21 men; mean age, 69 +/- 13 years) but differed significantly in breathlessness-related impairment, intensity, and quality of life (p < 0.0001). Cluster membership corresponded accurately with original group classifications (volunteered, 85%; and up to three statements, 68% agreement). Classification based on a single best descriptor (volunteered [62%] or endorsed [55%]) was less accurate for group membership.

CONCLUSIONS

Language used to describe the sensation of breathlessness differentiated people with and without a prior diagnosis of COPD when descriptors were not limited to a single best word or statement.

Distractive Auditory Stimuli Reduce the Unpleasantness of Dyspnea During Exercise in Patients With COPD

BACKGROUND

Dyspnea is the primary symptom limiting exercise in patients with COPD. Recent research has demonstrated that psychological factors can substantially influence the perception of dyspnea, but little is known about the modulation of perceived intensity or unpleasantness of dyspnea by attentional distraction. Therefore, we examined the impact of distractive auditory stimuli on the perception of exercise-induced dyspnea and the affective state in patients with COPD during 6-min walking tests (6MWTs).

METHODS

Twenty patients with mild-to-severe COPD (mean FEV1, 55.9% predicted) underwent two 6MWTs. Under one exercise condition, distractive auditory stimuli were presented with headphones, while the other condition was performed without auditory distraction. Lung function (FEV1), heart rate (HR), pulse oximetric saturation (SpO2), perceived intensity of dyspnea (ie, visual analog scale for perceived intensity of dyspnea [VAS-I]), and perceived unpleasantness of dyspnea (visual analog scale for perceived unpleasantness of dyspnea [VAS-U]) were measured before and after exercise. In addition, the global level of dyspnea (Borg score), positive affectivity (PA), and negative affectivity were assessed after both conditions.

RESULTS

A similar exercise level during both conditions was confirmed by comparable results in FEV1, HR, SpO2, and distances walked. During auditory distraction, Borg scores and increases in VAS-U were smaller, while PA was higher compared to the nondistraction condition (p<0.05). VAS-I did not show differences across conditions.

CONCLUSIONS

Distractive auditory stimuli decrease the global level of exercise-induced dyspnea in patients with COPD by reducing the perceived unpleasantness of dyspnea and lead to an additional increase in PA. Auditory distraction might therefore serve as an intervention for the reduction of dyspnea during exercise in this patient group.

Dyspnea and symptom amplification in asthma

BACKGROUND

The severity of a patient's asthma and the intensity with which he describes his dyspnea do not correlate.

OBJECTIVES

There is an indirect relationship between airway function in asthma and the intensity of dyspnea; this relationship is found only when the measure of a patient's general tendency to exaggerate the intensity of any somatic symptom is considered simultaneously.

METHODS

Lung function, including spirometry (forced expiratory volume in 1 s, FEV(1)) and plethysmography (airway resistance, R(aw)), dyspnea (Borg scale score) and the tendency to exaggerate (the somatosensory amplification scale score, SSAS) have been quantified in 42 stable asthmatic patients.

RESULTS

There was no correlation between the Borg score and any spirometric or plethysmographic measure in these subjects. By contrast, there was a moderate correlation between the Borg score and the SSAS (r = 0.36, p = 0.03). However, when FEV(1) or R(aw) (abscissa) and Borg scores (ordinate) were converted to residuals, there was a moderate correlation between the residuals and the SSAS score (for FEV(1), r = 0.33 and p = 0.05; for R(aw), r = -0.36 and p = 0.03).

CONCLUSION

A physician may make a reasonable estimate of an asthmatic patient's lung function from the intensity of his complaint only if he - the physician - considers the patient's tendency to symptom amplify as well.

The influence of corticosteroids on the perception of dyspnea in asthma

Corticosteroids are effective anti-inflammatory medications that are recommended for the control of persistent asthma. Little, however, is known about their influence on the perception of dyspnea, which, in turn, is important to the successful self-management of asthma. This paper provides a synopsis of available studies examining the impact of corticosteroids on the sensitivity to perceive dyspnea and presents possible mechanisms underlying this relationship. The results of these investigations are conflicting with some studies showing improved perception and other studies showing worsened perception of dyspnea after corticosteroid treatment. Thus, firm conclusions cannot be derived from the currently available data. Implications for future research, which is required to increase our understanding of potential influences of corticosteroids on the perception of dyspnea, are provided.