Accuracy of respiratory symptom perception in different affective contexts

The impact of emotion on the perception of graded magnitudes of respiratory resistive loads

Emotional state can modulate the perception of respiratory loads but the range of respiratory load magnitudes affected by emotional state is unknown. We hypothesized that viewing pleasant, neutral and unpleasant affective pictures would modulate the perception of respiratory loads of different load magnitudes. Twenty-four healthy adults participated in the study. Five inspiratory resistive loads of increasing magnitude (5, 10, 15, 20, 45 cm H(2)O/L/s) were repeatedly presented for one inspiration while participants viewed pleasant, neutral and unpleasant affective picture series. Participants rated how difficult it was to breathe against the load immediately after each presentation. Only at the lowest load, magnitude estimation ratings were greater when subjects viewed the unpleasant series compared to the neutral and pleasant series. These results suggest that negative emotional state increases the sense of respiratory effort for single presentations of a low magnitude resistive load but high magnitude loads are not further modulated by emotional state.

Self-reported health bias: the role of daily affective valence and arousal

OBJECTIVE

The present study addresses gaps in the literature on affect-biased health perceptions by (a) investigating health bias while considering both valence and arousal components of affect; (b) establishing the presence of, and variability in, affective health bias at the daily level; and (c) exploring daily health bias in a non-clinical, community sample of adults.

DESIGN

Participants were 477 adults (aged 33-80 years) who reported daily health events, health satisfaction and affect for up to 56 days. Health bias was present when the effect of a given day's health events on that day's health satisfaction was significantly moderated by that day's affect. Multilevel modelling was used to investigate fixed and random within-day effects.

MAIN OUTCOME MEASURE

Daily health satisfaction.

RESULTS

Significant interaction effects indicated the presence of health bias on the daily level: positively valenced affect buffered the negative impact of health events on health satisfaction, whereas negatively valenced affect exacerbated this association; additionally, valence emerged as the most salient characteristic of positive affect, whereas arousal was a differentiating factor for negative affect.

CONCLUSION

The results provide evidence that both valence and arousal components of affect are important to consider when investigating day-level health bias, and that these effects can be detected using a general population of adults.

The impact of emotions on symptom perception in patients with asthma and healthy controls

Accurate perception of respiratory symptoms is highly important for course and treatment of asthma. Recent findings suggest that emotions can greatly impact respiratory symptom perception. This study compared the impact of emotions on respiratory symptom perception between patients with asthma and matched healthy controls. Pleasant and unpleasant emotional states were elicited by viewing emotional picture series while symptom reports and respiratory parameters were measured. Greater symptom report was observed for the unpleasant compared to the pleasant emotional state that was not related to respiratory parameters. Notably, this effect was comparable between patients with asthma and healthy controls. The present results suggest that the impact of emotions on respiratory symptom perception is a rather general phenomenon and not dependent upon previous experiences with asthma symptoms.

Review of evidence for a toxicological mechanism of idiopathic environmental intolerance

Idiopathic environmental intolerance (IEI) is a medically unexplained disorder characterised by a wide variety of unspecific symptoms in different organ systems and attributed to nontoxic concentrations of chemicals and other environmental factors that are tolerated by the majority of individuals. Both exposure to chemicals and behavioural conditioning are considered as possible contributors to the development of IEI. However, owing to the heterogeneity of the condition, it is difficult to separate the toxicological, physiological and psychological aspects of IEI. Here, we review the evidence for postulated toxicologically mediated mechanisms for IEI. Available data do not support either a classical receptor-mediated or an idiosyncratic toxicological mechanism. Furthermore, if there were convincing evidence for a psychological cause for many patients with IEI, then this would suggest that the priority for the future is the development of psychological treatments for IEI. Finally, we advocate genome wide screening of IEI patients to elucidate genotypic features of the condition.

The effect of anxiety on respiratory sensory gating measured by respiratory-related evoked potentials

Respiratory sensory gating is evidenced by decreased amplitudes of the respiratory-related evoked potentials (RREP) N1 peak for the second (S2) compared to the first occlusion (S1) when two paired occlusions are presented with a 500-millisecond (ms) inter-stimulus-interval during one inspiration. Because anxiety is prevalent in respiratory diseases and associated with altered respiratory perception, we tested whether anxiety can modulate individuals' respiratory neural gating mechanism. By using high-density EEG, RREPs were measured in a paired inspiratory occlusion paradigm in 11 low and 10 higher anxious individuals with normal lung function. The N1 peak gating S2/S1 ratio and the N1 S2 amplitudes were greater in higher compared to low anxious individuals (p's<0.05). In addition, higher anxiety levels were correlated with greater S2/S1 ratios (r=0.54, p<0.05) and S2 amplitudes (r=-0.49, p<0.05). The results demonstrate that anxiety is associated with reduced respiratory sensory gating which might underlie altered respiratory symptom perception in anxious individuals.

Indoor air pollutants in office environments: assessment of comfort, health, and performance

Concentrations of volatile organic compounds (VOCs) in office environments are generally too low to cause sensory irritation in the eyes and airways on the basis of estimated thresholds for sensory irritation. Furthermore, effects in the lungs, e.g. inflammatory effects, have not been substantiated at indoor relevant concentrations. Some VOCs, including formaldehyde, in combination may under certain environmental and occupational conditions result in reported sensory irritation. The odour thresholds of several VOCs are low enough to influence the perceived air quality that result in a number of acute effects from reported sensory irritation in eyes and airways and deterioration of performance. The odour perception (air quality) depends on a number of factors that may influence the odour impact. There is neither clear indication that office dust particles may cause sensory effects, even not particles spiked with glucans, aldehydes or phthalates, nor lung effects; some inflammatory effects may be observed among asthmatics. Ozone-initiated terpene reaction products may be of concern in ozone-enriched environments (≥0.1mg/m(3)) and elevated limonene concentrations, partly due to the production of formaldehyde. Ambient particles may cause cardio-pulmonary effects, especially in susceptible people (e.g. elderly and sick people); even, short-term effects, e.g. from traffic emission and candle smoke may possibly have modulating and delayed effects on the heart, but otherwise adverse effects in the airways and lung functions have not been observed. Secondary organic aerosols generated in indoor ozone-initiated terpene reactions appear not to cause adverse effects in the airways; rather the gaseous products are relevant. Combined exposure to particles and ozone may evoke effects in subgroups of asthmatics. Based on an analysis of thresholds for odour and sensory irritation selected compounds are recommended for measurements to assess the indoor air quality and to minimize reports of irritation symptoms, deteriorated performance, and cardiovascular and pulmonary effects.

Tactile perceptual processes and their relationship to medically unexplained symptoms and health anxiety

OBJECTIVE

The Somatic Signal Detection Task (SSDT; Lloyd, Manson, Brown and Poliakoff, 2008) is an innovative paradigm to study perceptual processes related to physical symptoms. It allows examining touch illusions as a laboratory analog of medically unexplained symptoms (MUS) according to the cognitive model of MUS proposed by Brown (2004). The present study compared psychopathologic measures of MUS and health anxiety with SSDT parameters. Furthermore, we aimed to define a reliable measurement of tactile perception threshold.

METHODS

67 participants of a student population reported whether they detected tactile stimuli at their fingertip which were presented in half of the test trials. An additional brief visual stimulus was displayed with a probability of 50%. The rate of false-positive perceptions of the tactile stimulus in its absence, response bias, tactile sensitivity, and tactile perception thresholds was recorded. Questionnaires were used to assess MUS and health anxiety.

RESULTS

The visual stimulus led to a more liberal response criterion (i.e., the tendency to report tactile perceptions irrespective of whether a stimulus was presented or not) and a non-significant increase in tactile sensitivity. The false-alarm rate when reporting the tactile stimulus was correlated with MUS (r=.26). Tactile perception thresholds were measured reliably (r(tt)=.84).

CONCLUSION

Some of the SSDT parameters, especially the response criterion (c), were related to self-report-measures of MUS and health anxiety. Previous SSDT results were replicated and extended. Further SSDT studies with clinical samples are needed.

The influence of fear of symptoms and perceived control on asthma symptom perception

OBJECTIVE

Self-reported asthma symptoms correlate only modestly with measures of underlying pathophysiological mechanisms. In this study, we investigated the role of fear of symptoms and perceived control on respiratory symptom perception in patients with asthma.

METHODS

Patients with intermittent to moderate persistent asthma (N=32) were administered 4 subsequent rebreathing challenges (one using 100% O(2) and three using 5% CO(2) and 95% O(2)). We manipulated perceived control by providing information on the availability/unavailability of rescue medication during the challenges (perceived control/no control condition). Perceived symptoms and lung function were assessed after each rebreathing challenge.

RESULTS

Persons with low fear of symptoms reported respiratory symptoms to be less unpleasant during the perceived control condition compared to the no control condition. The reverse was found for persons with high fear of symptoms. The interaction between fear of symptoms and the control manipulations was mediated by threat perception.

CONCLUSION

Messages intended to increase perceived control over symptoms may actually increase threat in persons with high fear of symptoms and eventually increase unpleasantness of respiratory sensations. This finding underlines the importance of affective processes in the perception of asthma symptoms and shows that instructions to patients should take pre-existing fear levels into account.

Controlled and uncontrolled allergic asthma in routine respiratory specialist care - a clinical-epidemiological study in Germany

BACKGROUND

Studies in the last decade showed high rates of poorly treated and poorly controlled asthma in the community. Extending these findings we describe the more recent situation in specialist respiratory care as the most frequent source of treatment provision using comprehensive clinical and patient assessments and exploring predictors for poor control.

METHODS

This is a German cross-sectional, clinical epidemiological study in a nationally representative stratified treatment prevalence sample of N = 572 outpatients diagnosed with allergic asthma (AA; females 58.2%, aged 47.5 ± 16.3 (16-81 years). Treating physicians completed standardized clinical assessments (lung function, laboratory, clinical findings, severity, illness and treatment history, asthma control [GINA]), supplemented by patients' self-report measures (EQ5-D, AQLQ, ACT) and mental health module (CIDI-SF).

RESULTS

A total of 65.4% of patients were rated (GINA) as controlled, 30.3% partially controlled, and 4.4% uncontrolled; the patient-rated ACT showed lower rates of control (19.9% controlled, 44.2% partial, 35.8% uncontrolled, kappa: 0.2). Consistent with findings of clinical measures, controlled asthma was highest among patients with pre-treatment stage I severity (83.6%) and decreased by pre-treatment severity (stage IV patients: 29.3%). Poorer control was associated with pre-treatment severity, nocturnal attacks, diminished adherence and comorbid anxiety/depression. Patients received complex multiple drug and non-drug interventions, largely consistent with guidelines. Degree of asthma control was associated with improved and even normalized quality of life findings.

CONCLUSION

In this representative sample of longterm treated AA patients in specialist respiratory care we find better control rates and better adherence to guidelines as previous studies. Despite remarkable differences in clinician- vs patient-rated control ratings even the initially most severe stage IV patients (12.9% of patients) showed remarkable control rates and close to normal quality of life. Intensified treatment (e.g. omalizumab) was associated with improved control. Poorer control was associated with higher initial severity, diminished adherence, comorbid anxiety/depression and old age.

LIMITATION

Findings apply to AA patients in respiratory specialist care sector which is likely to treat the more severely affected patients. Thus, findings cannot be generalized to the general population, other treatment settings or asthma types.

Increased interoceptive awareness in fear of flying: sensitivity to suffocation signals

In flight phobia, particular environmental factors can facilitate a fear response. The current study aimed to explore the relationship between respiratory sensations and fear of flying: individuals with fear of flying may be more sensitive to suffocation signals and could experience more bodily sensations as a consequence of an added resistive respiratory load. The sample included 19 subjects with fear of flying and 19 controls. Each subject wore a mask to which a respiratory load could be added. First, an interference paradigm was used: respiratory loads were presented during a tone detection task. Next, subjects were asked to detect the loads. After each task, subjects reported their somatic sensations. All subjects showed interference of the respiratory loads. However, subjects with fear of flying were more accurate in detecting the loads, thereby indicating higher interoceptive awareness. Moreover, their superior accuracy was related to increased bodily sensations: a higher interoceptive awareness resulted in increased symptom reporting. It follows that treatment interventions for fear of flying should be supplemented with interventions that target internal stimuli.

The impact of anxiety on the neural processing of respiratory sensations

Previous studies demonstrated that anxiety considerably impacts the reported perceptions of respiratory sensations. A novel feature of the current study is exploring the impact of anxiety on the neural processing of respiratory sensations elicited by short inspiratory occlusions during different affective contexts. Using high-density EEG, respiratory-related evoked potentials (RREP) were recorded in 23 low and 23 matched higher anxious individuals when viewing unpleasant or neutral picture series. Low anxious individuals showed the expected pattern of reduced magnitudes of later RREP components P2 and P3 during the unpleasant compared to the neutral affective context (p<0.05 and p<0.01). In contrast, higher anxious individuals showed greater magnitudes of P2 and P3 during the unpleasant compared to the neutral affective context (p's<0.05). Moreover, higher anxiety levels were correlated with greater magnitudes for P2 (r=0.44, p<0.01) and P3 (r=0.54, p<0.001) during the unpleasant relative to the neutral affective context. Earlier components of the RREP (Nf, P1, N1) were not affected by anxiety. This study demonstrates that anxiety affects the later, higher-order neural processing of respiratory sensations, but not its earlier, first-order sensory processing. These findings might represent a neural mechanism that underlies the increased perception of respiratory sensations in anxious individuals.

Dyspnoea and the brain

Chronic dyspnoea is a devastating symptom that debilitates millions of people worldwide. It causes a large burden on both patient and carer, and significant costs to society and health services. Treatment options are limited. Much effort has been directed at optimising lung function and improving exercise capacity, however, the brain mechanisms underlying dyspnoea perception have received less attention. In this review, we focus on cognitive and affective aspects of dyspnoea and discuss how novel neuroimaging methods can provide quantitative measures of these subjective sensations. We draw parallels with the more advanced field of chronic pain, and explain some of the challenges faced when imaging dyspnoea. To date, brain mechanisms of dyspnoea have been investigated in a handful of studies by a limited number of authors. These have found consistent activation in the insular cortex, the anterior cingulate cortex and the amygdala. Novel neuroimaging methods and an improved understanding of perceptual mechanisms underlying dyspnoea now position us to transform dyspnoea research. Future research should investigate how brain regions associated with dyspnoea interact, as well as accurately correlate this neuronal activation with reliable behavioural measures. A better understanding of the brain processes underlying dyspnoea perception will lead to new therapies that will improve quality of life for a very large group of patients.

The role of nicotine on respiratory sensory gating measured by respiratory-related evoked potentials

Respiratory perception can be altered by changes in emotional or psychological states. This may be due to affective (i.e., anxiety) modulation of respiratory sensory gating. Nicotine withdrawal induces elevated anxiety and decreased somatosensory gating. Respiratory sensory gating is evidenced by decreased amplitude of the respiratory-related evoked potentials (RREP) N1 peak for the second occlusion (S2) when two 150-ms occlusions are presented with a 500-ms interval during an inspiration. The N1 peak amplitude ratio of the S2 and first occlusion (S1) (S2/S1) is <0.5 and due to central neural sensory gating. We hypothesized that withdrawal from nicotine is anxiogenic and reduces respiratory gating in smokers. The RREP was recorded in smokers with 12-h withdrawal from nicotine and nonsmokers using a paired occlusion protocol. In smokers, the RREP was measured after nicotine withdrawal, then with either nicotine or placebo gum, followed by the second RREP trial. Nonsmokers received only placebo gum. After nicotine withdrawal, the smokers had a higher state anxiety compared with nonsmokers. There was a significant interaction between groups (nonsmokers vs. smokers with nicotine vs. smokers with placebo) and test (pre- vs. posttreatment) in RREP N1 peak amplitude S2/S1. The S2/S1 in the smokers were larger than in nonsmokers before treatment. After gum treatment, the smoker-with-placebo group had a significantly larger S2/S1 than the other two groups. The S2/S1 was significantly decreased after the administration of nicotine gum in smokers due to significantly decreased S2 amplitudes. The RREP Nf and P1 peaks were unaffected. These results demonstrated that respiratory sensory gating was decreased in smokers after nicotine withdrawal. Nicotine increased respiratory sensory gating in smokers with a S2/S1 similar to that of the nonsmokers. Nicotine did not change respiratory sensory information arrival, but secondary information processing in respiratory sensation.

The impact of emotion on respiratory-related evoked potentials

Emotion influences the perception of respiratory sensations, although the specific mechanism underlying this modulation is not yet clear. We examined the impact of viewing pleasant, neutral, and unpleasant affective pictures on the respiratory-related evoked potential (RREP) elicited by a short inspiratory occlusion in healthy volunteers. Reduced P3 amplitude of the RREP was found for respiratory probes presented when viewing pleasant or unpleasant series, when compared to those presented during the neutral series. Earlier RREP components, such as Nf, P1, N1, and P2, showed no modulation by emotion. The results suggest that emotion impacts the perception of respiratory sensations by reducing the attentional resources available for processing afferent respiratory sensory signals.

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.

Inaccurate perception of asthma symptoms: a cognitive-affective framework and implications for asthma treatment

Inaccurate perception of respiratory symptoms is often found in asthma patients. Typically, patients who inaccurately perceive asthma symptoms are divided into underperceivers and overperceivers. In this paper we point out that this division is problematic. We argue that little evidence exists for a trait-like stability of under- and overperception and that accuracy of respiratory symptom perception is highly variable within persons and strongly influenced by contextual information. Particularly, expectancy and affective cues appear to have a powerful influence on symptom accuracy. Based on these findings and incorporating recent work on associative learning, attention and mental representations in anxiety and symptom perception, we propose a cognitive-affective model of symptom perception in asthma. The model can act as a framework to understand both normal perception as well as under- and overperception of asthma symptoms and can guide the development of affect-related interventions to improve perceptual accuracy, asthma control and quality of life in asthma patients.

High symptom reporters are less interoceptively accurate in a symptom-related context

OBJECTIVE

We investigated the role of a symptom interpretation frame on the accuracy of interoception and on retrospective symptom reporting in nonclinical high and low reporters of medically unexplained symptoms.

METHODS

All participants (N=74) went through two subsequent trials of the Rebreathing Test, inducing altered respiration and other physical sensations as a result of a gradually increasing pCO(2) level in the blood. Each trial consisted of a baseline (60 s), a rebreathing phase (150 s), and a recovery phase (150 s). In one trial, the sensations were framed in a neutral way ("the gas mixture might alter breathing behavior and induce respiratory sensations"). In the other trial, a symptom frame was induced ("the gas mixture might alter breathing behavior and induce respiratory symptoms"). Breathing behavior was continuously monitored, subjective sensations were rated every 10 s, and after each trial, participants filled out a symptom checklist. Within-subject correlations between the subjective rating and its physiological referent were calculated for the rebreathing phase and recovery phase of each trial separately.

RESULTS

High symptom reporters had more (retrospective) complaints than low symptom reporters, especially in the symptom trial. Only in the symptom frame were high symptom reporters less accurate than low symptom reporters. The reduction in interoceptive accuracy (IA) in high symptom reporters was most striking in the recovery phase of the symptom frame trial.

CONCLUSION

A contextual cue, such as a reference to symptoms, reduced IA in high symptom reporters and this was more so during recovery from the symptom induction.

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.

[Perception of asthma control in asthma patients]

OBJECTIVE

To determine the proportion of asthma patients with poor perception of asthma control and to evaluate the characteristics of this subgroup.

METHODS

A cross-sectional study in which consecutive outpatients (over the age of 12) with mild, moderate, or severe asthma were selected. The patients underwent clinical examination and pulmonary function tests, as well as being assessed for depression and perception of asthma control. The degree of concordance between patients and physicians regarding the perception of asthma control was determined. Patients with good perception of asthma control were compared, in terms of characteristics, with those presenting poor perception.

RESULTS

The degree of concordance between patients and physicians regarding the perception of asthma control was low (kappa index = 0.5). Of the 289 patients included, 66 (23%) presented poor perception of asthma control. The preliminary univariate analysis revealed that the patients with poor perception of asthma control were older, had a lower income, and presented a lower degree of asthma severity. Those factors did not change in the multivariate analysis. There were no differences between the groups in terms of gender, frequency of having literate patients, duration of asthma symptoms, having been diagnosed with rhinitis, frequency of depression, pulmonary function, or treatment compliance.

CONCLUSIONS

The incidence of poor perception of asthma control in asthma patients is high, especially in elderly patients with lower income and a lower degree of asthma severity.

Repeated experiences of air hunger and ventilatory behavior in response to hypercapnia in the standardized rebreathing test: effects of anxiety

In this study, we assessed air hunger (AH) and ventilatory responses to repeated CO(2) exposures in healthy women (N=31), scoring high or low for trait anxiety. A standardized rebreathing test, implying a gradually increasing CO(2) stimulus, was administered three times with 15-min intervals. Respiratory behavior and the intensity of AH perception were measured continuously. Across repeated exposures, maximal tolerance for AH habituated and the slope of AH (increase in AH per unit increase in CO(2)) diminished. Also the dynamics of the breathing response changed across trials. The thresholds for AH and tidal volume (V(T)) moved closer to each other, whereas the threshold for the respiratory rate (RR) was generally postponed. In addition, the association between AH and V(T) was stronger than between AH and RR, and the latter association became weaker over trials, particularly in high anxious persons. This suggests that AH perception became increasingly influenced by psychological factors, especially in high anxious persons. The results suggest that habituation of perceived air hunger is depending on a complex interplay between both changes in respiratory behavior and in perceptual-cognitive processes related to trait anxiety.

The relationship between dyspnea and blood pressure in chronic obstructive pulmonary disease

BACKGROUND AND RESEARCH OBJECTIVE

Although dyspnea is a frequently encountered clinical symptom, precise clinical evaluation of this sensation remains illusive. Dyspnea has been difficult to evaluate empirically, as severity of mechanical pulmonary impairment does not appear to correlate with subjectively reported levels of dyspnea. The purpose of this study was to describe changes in dyspnea and blood pressure with the use of an incentive spirometry and to examine the relationship of such changes in patients with chronic obstructive pulmonary disease.

SUBJECTS AND METHODS

A convenience sample of 60 adults diagnosed with chronic obstructive pulmonary disease was recruited from ambulatory outpatient clinics at a large Veterans hospital. A quantitative single-group, within-subjects repeated-measure design was used to investigate the relationship between the variables following incentive spirometry. Dyspnea levels were recorded with the visual analog scale and arterial blood pressures (beat-to-beat systolic, mean, and diastolic) were continuously recorded with tonometry.

RESULTS AND CONCLUSIONS

The first 4 periods following use of the incentive spirometer were found to have statistically significant increases from dyspnea baseline scores (F = 77.4, P < .001). The baseline of each of the arterial blood pressure measurements, systolic, mean, and diastolic, were found to have significant differences with all of the 6 postintervention time points (systolic F = 8.0, P < .001; mean F = 7.1, P < .001; diastolic F = 7.2, P < .001). The changes in dyspnea scores and blood pressure measurements were found to have significant inverse correlations at the immediate postintervention time point (r = -0.32 to -0.35, P < .01). Results provide evidence of an inverse relationship between dyspnea and blood pressure patterns and may indicate significant clinical associations to add to the body of knowledge about the symptom of dyspnea.

Hyperventilation in patients with chronic fatigue syndrome: the role of coping strategies

Hyperventilation has been suggested as a concomitant and possible maintaining factor that may contribute to the symptom pattern of chronic fatigue syndrome (CFS). Because patients accepting the illness and trying to live with it seem to have a better prognosis than patients chronically fighting it, we investigated breathing behavior during different coping response sets towards the illness in patients with CFS (N=30, CDC criteria). Patients imagined a relaxation script (baseline), a script describing a coping response of hostile resistance, and a script depicting acceptance of the illness and its (future) consequences. During each imagery trial, end-tidal PCO2 (Handheld Capnograph, Oridion) was measured. After each trial, patients filled out a symptom checklist. Results showed low resting values of PetCO2 overall, while only imagery of hostile resistance triggered a decrease and deficient recovery of PetCO2. Also, more hyperventilation complaints and complaints of other origin were reported during hostile resistance imagery compared with acceptance and relaxation. In conclusion, hostile resistance seems to trigger both physiological and symptom perception processes contributing to the clinical picture of CFS.

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

BACKGROUND

Recent research has shown that distinct dimensions in the perception of dyspnea can be differentiated; however, most studies to date have only used a global rating scale for the measurement of this sensation.

OBJECTIVES

This study examined the different influence of sensory and affective aspects of perceived dyspnea on the commonly used Borg scale, which measures the global perception of dyspnea.

METHODS

Dyspnea was induced in 16 healthy volunteers (mean age 26.2 +/- 6.3 years) by breathing through an inspiratory resistive load (3.57 kPa/l/s) in two experimental conditions (attention and distraction). After each of the two conditions the experienced intensity (i.e., sensory dimension) and unpleasantness (i.e., affective dimension) of dyspnea were rated on separate visual analog scales (VAS), followed by a global rating of dyspnea on the Borg scale. Hierarchical multiple linear regression models were calculated to analyze the predictive validity of VAS ratings of intensity and unpleasantness on the Borg scale ratings.

RESULTS

When subjects attended to their breathing, only VAS intensity scores showed a significant influence on Borg scale ratings (p < 0.05). In contrast, only the VAS unpleasantness scores showed a significant influence on Borg scale ratings (p < 0.05) when subjects were distracted.

CONCLUSIONS

These findings show that sensory and affective aspects of perceived dyspnea differentially influence the global measure of dyspnea as determined by the Borg scale. A differentiation between these aspects in future studies through the use of separate rating scales could yield more detailed information on the perception and report of dyspnea.

Differentiation between the sensory and affective aspects of histamine-induced bronchoconstriction in asthma

Respiratory symptom perception research has focused mainly on respiratory sensations. Because dyspnea is multidimensional, affective aspects should be investigated. Patients with asthma (N=25) underwent a histamine provocation until a 20% fall in forced expiratory volume in 1s (FEV(1)). After each dose level, 6 symptoms of dyspnea intensity and 6 symptoms of dyspnea affectivity were rated. Individual perceptual sensitivity was determined by calculating the linear slope between the fall in FEV(1) and the increase in the total symptom score, and for affective and sensory symptoms separately [Bijl-Hofland, Folgering, van den Hoogen, et al. Perception of bronchoconstriction in asthma patients measured during histamine challenge test. Eur Respir J 1999;14:1049-54]. Trait anxiety, baseline state anxiety, daily asthma symptoms and catastrophizing during an asthma exacerbation were also assessed. Sensitivity was unrelated to physiological indices of disease severity (i.e., baseline FEV(1) and histamine dose level at 20% fall in FEV(1)), whereas it was positively related to trait anxiety, state anxiety, daily asthma symptoms and catastrophic thinking during an asthma exacerbation in daily life. These relationships were overall much stronger for affective than for sensory symptom slopes. In stepwise multiple regressions, state anxiety was the best predictor of the affective symptom slopes, whereas catastrophic thinking during an asthma exacerbation was the best predictor for the sensory symptom slopes. The differentiation between sensory and affective components of dyspnea adds to the understanding of respiratory symptom perception in asthma.

Psychological aspects in the perception of dyspnea in obstructive pulmonary diseases

Dyspnea is an impairing symptom in obstructive pulmonary diseases. Besides multiple physiological pathways contributing to this sensation recent research has demonstrated an important role of psychological factors in the perception of dyspnea. The present review article synthesizes the research literature with regard to psychological aspects of the perception of dyspnea as well as other dyspnea-related issues such as course of disease, neuropsychological correlates and interventions that focus on psychological or behavioural changes. The available data show that inaccurate perception of dyspnea is related to poorer treatment outcome in obstructive pulmonary diseases and is impacted upon by emotional, attentional and learning processes. Neuropsychological deficits might further contribute to this association. Different psychological and behavioural interventions might reduce comorbid psychological disorders and thus improve the perception of dyspnea. However, future research is clearly required to substantiate current findings.

The impact of emotions on the sensory and affective dimension of perceived dyspnea

Dyspnea is an impairing symptom in various diseases. Recent research has shown that the perception of dyspnea, like pain, consists of a sensory (intensity) and an affective (unpleasantness) dimension, but little is known about the specific impact of different emotions on these distinct dimensions. We therefore examined the impact of viewing affective picture series of positive, neutral, and negative valence on perceived dyspnea during resistive load breathing in healthy volunteers. Inspiratory time (Ti), breathing frequency (f), and oscillatory resistance (Ros) remained unchanged across conditions. Ratings for unpleasantness of dyspnea increased from positive to neutral to negative series, but ratings for intensity of dyspnea showed no changes. The results suggest that the affective dimension of the perception of dyspnea is particularly vulnerable to emotional influences, irrespective of objective lung function.

Air hunger and ventilation in response to hypercapnia: Effects of repetition and anxiety

We investigated the effects of anxiety on the intensity of air hunger during gradually increasing levels of CO2 until the end-tidal fractional concentration of CO2 was 7.9% or air hunger was intolerable. Normal high and low (trait) anxious participants (N=23) went through three rebreathing trials (15 min interval). Breathing behaviour was continuously monitored and air hunger was rated every 12 s. The threshold for responding to the increased CO2 was always lower for the subjective rating than for the ventilatory response. Habituation across trials was observed for both the ventilatory response and the air hunger rating regardless of anxiety. However, beyond the threshold, the slope in air hunger ratings decreased across trials in low anxious persons and tended to increase in high anxious persons (interaction P<0.05). No differences occurred in the slopes of the breathing responses. The findings documented uncoupling of the physiological and subjective responses during CO2-induced air hunger.