Interoception of respiratory resistance in asthmatic patients

Vague sensations. About the background and consequences of discordance between actual and perceived physiological changes

Empirical evidence consistently shows that discordance, also called dissociation or discrepancy, between actual physiological (mainly visceral) events and their perceived counterparts is substantial. On the one hand, we typically do not perceive actual visceral events occurring in our bodies; on the other hand, sometimes we do perceive bodily changes that do not really take place. This narrative review presents the available empirical findings on the discordance, and summarizes possible explanations that approach the phenomenon from the viewpoint of evolution, cognitive development, and predictive processing. Also, the role of top-down factors, such as expectations and experiences is discussed. Finally, practically relevant consequences of the discordance are presented using the examples of mind-body practices, the placebo and nocebo phenomenon, and medically unexplained symptoms. It is concluded that the discordance between actual and perceived body changes can have a negative impact on health, mainly through issues with adherence and other behavioral factors. The existence of actual-perceived discordance should be taught and demonstrated in the elementary and high school, as well as in many areas of higher education.

Sensory and affective aspects of the perception of respiratory resistance

Perception of airway resistance has a sensory and an affective aspect, i.e., perceived resistance and unpleasantness, respectively. The current study aimed to shed more light on the relationship of these aspects, as well as their malleability to trait-like aspects of body awareness. In a laboratory study, 71 young participants completed two respiratory resistive load discrimination tasks relying on sensory and affective evaluation, respectively, and filled out questionnaires assessing somatosensory amplification, anxiety sensitivity, somatic symptoms distress, and breath awareness. Frequentist and Bayesian statistical analysis revealed no differences in discrimination accuracy with respect to the sensory and affective aspect of perceived resistance. Psychological traits were not associated with accuracy scores. In conclusion, affective evaluation of respiratory load is as accurate as sensory evaluation. Neither sensory not affective accuracy is influenced by various aspects of body awareness.

Interoceptive pathways to understand and treat mental health conditions

An increasing recognition that brain and body are dynamically coupled has enriched our scientific understanding of mental health conditions. Peripheral signals interact centrally to influence how we think and feel, generating our sense of the internal condition of the body, a process known as interoception. Disruptions to this interoceptive system may contribute to clinical conditions, including anxiety, depression, and psychosis. After reviewing the nature of interoceptive disturbances in mental health conditions, this review focuses on interoceptive pathways of existing and putative mental health treatments. Emerging clinical interventions may target novel peripheral treatment mechanisms. Future treatment development requires forward- and back-translation to uncover and target specific interoceptive processes in mental health to elucidate their efficacy relative to interventions targeting other factors.

Recent insights into respiratory modulation of brain activity offer new perspectives on cognition and emotion

Over the past six years, a rapidly growing number of studies have shown that respiration exerts a significant influence on sensory, affective, and cognitive processes. At the same time, an increasing amount of experimental evidence indicates that this influence occurs via modulation of neural oscillations and their synchronization between brain areas. In this article, we review the relevant findings and discuss whether they might inform our understanding of a variety of disorders that have been associated with abnormal patterns of respiration. We review literature on the role of respiration in chronic obstructive pulmonary disease (COPD), anxiety (panic attacks), and autism spectrum disorder (ASD), and we conclude that the new insights into respiratory modulation of neuronal activity may help understand the relationship between respiratory abnormalities and cognitive and affective deficits.

The breathing brain: The potential of neural oscillations for the understanding of respiratory perception in health and disease

Dyspnea or breathlessness is a symptom occurring in multiple acute and chronic illnesses, however, the understanding of the neural mechanisms underlying its subjective experience is limited. In this topical review, we propose neural oscillatory dynamics and cross-frequency coupling as viable candidates for a neural mechanism underlying respiratory perception, and a technique warranting more attention in respiration research. With the evidence for the potential of neural oscillations in the study of normal and disordered breathing coming from disparate research fields with a limited history of interdisciplinary collaboration, the main objective of the review was to converge the existing research and suggest future directions. The existing findings show that distinct limbic and cortical activations, as measured by hemodynamic responses, underlie dyspnea, however, the time-scale of these activations is not well understood. The recent findings of oscillatory neural activity coupled with the respiratory rhythm could provide the solution to this problem, however, more research with a focus on dyspnea is needed. We also touch on the findings of distinct spectral patterns underlying the changes in breathing due to experimental manipulations, meditation and disease. Subsequently, we suggest general research directions and specific research designs to supplement the current knowledge using neural oscillation techniques. We argue for the benefits of interdisciplinary collaboration and the converging of neuroimaging and behavioral methods to best explain the emergence of the subjective and aversive individual experience of dyspnea.

Respiratory modulation of intensity ratings and psychomotor response times to acoustic startle stimuli

Respiratory interoception may play an important role in the perception of respiratory symptoms in pulmonary diseases. As the respiratory cycle affects startle eye blink responses, startle modulation may be used to assess visceral-afferent signals from the respiratory system. To ascertain the potential impact of brainstem-relayed signals on cortical processes, we investigated whether this pre-attentive respiratory modulation of startle (RMS) effect is also reflected in the modulation of higher cognitive, evaluative processing of the startle stimulus. Twenty-nine healthy volunteers received 80 acoustic startle stimuli (100 or 105 dB(A); 50 ms), which were presented at end and mid inspiration and expiration, while performing a paced breathing task (0.25 Hz). Participants first responded to the startle probes by 'as fast as possible' button pushes and then rated the perceived intensity of the stimuli. Psychomotor response time was divided into 'reaction time' (RT; from stimulus onset to home button release; represents stimulus evaluation) and 'movement time' time (MT; from home button release to target button press). Intensity judgments were higher and RTs accelerated during mid expiration. No effect of respiratory cycle phase was found on eye blink responses and MTs. We conclude that respiratory cycle phase affects higher cognitive, attentional processing of startle stimuli.

Breathlessness and the brain: the role of expectation

PURPOSE OF REVIEW

Breathlessness debilitates countless people with a wide range of common diseases. For some people, the experience of breathlessness is poorly explained by the findings of medical tests. This disparity complicates diagnostic and treatment options and means that disease-modifying treatments do not always have the expected effect upon symptoms. These observations suggest that brain processing of respiratory perceptions may be somewhat independent of disease processes. This may help to explain the dissonance observed in some patients between physical disease markers and the lived experience of breathlessness.

RECENT FINDINGS

A body of breathlessness research using functional neuroimaging has identified a relatively consistent set of brain areas that are associated with breathlessness. These areas include the insula, cingulate and sensory cortices, the amygdala and the periaqueductal gray matter. We interpret these findings in the context of new theories of perception that emphasize the importance of distributed brain networks. Within this framework, these perceptual networks function by checking an internal model (a set of expectations) against peripheral sensory inputs, instead of the brain acting as a passive signal transducer. Furthermore, other factors beyond the physiology of breathlessness can influence the system.

SUMMARY

A person's expectations and mood are major contributors to the function of the brain networks that generate perceptions of breathlessness. Breathlessness, therefore, arises from inferences made by the brain's integration of both expectations and sensory inputs. By better understanding individual differences across these contributing perceptual factors, we will be better poised to develop targeted and individualized treatments for breathlessness that could complement disease-modifying therapies.

Respiratory modulation of startle eye blink: a new approach to assess afferent signals from the respiratory system

Current approaches to assess interoception of respiratory functions cannot differentiate between the physiological basis of interoception, i.e. visceral-afferent signal processing, and the psychological process of attention focusing. Furthermore, they typically involve invasive procedures, e.g. induction of respiratory occlusions or the inhalation of CO₂-enriched air. The aim of this study was to test the capacity of startle methodology to reflect respiratory-related afferent signal processing, independent of invasive procedures. Forty-two healthy participants were tested in a spontaneous breathing and in a 0.25 Hz paced breathing condition. Acoustic startle noises of 105 dB(A) intensity (50 ms white noise) were presented with identical trial frequency at peak and on-going inspiration and expiration, based on a new pattern detection method, involving the online processing of the respiratory belt signal. The results show the highest startle magnitudes during on-going expiration compared with any other measurement points during the respiratory cycle, independent of whether breathing was spontaneous or paced. Afferent signals from slow adapting phasic pulmonary stretch receptors may be responsible for this effect. This study is the first to demonstrate startle modulation by respiration. These results offer the potential to apply startle methodology in the non-invasive testing of interoception-related aspects in respiratory psychophysiology.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Interoceptive dimensions across cardiac and respiratory axes

Interoception refers to the sensing of signals concerning the internal state of the body. Individual differences in interoceptive sensitivity are proposed to account for differences in affective processing, including the expression of anxiety. The majority of investigations of interoceptive accuracy focus on cardiac signals, typically using heartbeat detection tests and self-report measures. Consequently, little is known about how different organ-specific axes of interoception relate to each other or to symptoms of anxiety. Here, we compare interoception for cardiac and respiratory signals. We demonstrate a dissociation between cardiac and respiratory measures of interoceptive accuracy (i.e. task performance), yet a positive relationship between cardiac and respiratory measures of interoceptive awareness (i.e. metacognitive insight into own interoceptive ability). Neither interoceptive accuracy nor metacognitive awareness for cardiac and respiratory measures was related to touch acuity, an exteroceptive sense. Specific measures of interoception were found to be predictive of anxiety symptoms. Poor respiratory accuracy was associated with heightened anxiety score, while good metacognitive awareness for cardiac interoception was associated with reduced anxiety. These findings highlight that detection accuracies across different sensory modalities are dissociable and future work can better delineate their relationship to affective and cognitive constructs.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Follow your breath: respiratory interoceptive accuracy in experienced meditators

Attention to internal bodily sensations is a core feature of mindfulness meditation. Previous studies have not detected differences in interoceptive accuracy between meditators and nonmeditators on heartbeat detection and perception tasks. We compared differences in respiratory interoceptive accuracy between meditators and nonmeditators in the ability to detect and discriminate respiratory resistive loads and sustain accurate perception of respiratory tidal volume during nondistracted and distracted conditions. Groups did not differ in overall performance on the detection and discrimination tasks; however, meditators were more accurate in discriminating the resistive load with the lowest ceiling effect. Meditators were also more accurate during the nondistracted tracking task at a lag time of 1 s following the breath. Results provide initial support for the notion that meditators have greater respiratory interoceptive accuracy compared to nonmeditators.

Psychosocial factors and behavioral medicine interventions in asthma

OBJECTIVE

This review examines the evidence for psychosocial influences in asthma and behavioral medicine approaches to its treatment.

METHOD

We conducted a systematic review of the literature on psychosocial influences and the evidence for behavioral interventions in asthma with a focus on research in the past 10 years and clinical trials. Additional attention was directed at promising new developments in the field.

RESULTS

Psychosocial factors can influence the pathogenesis and pathophysiology of asthma, either directly through autonomic, endocrine, immunological, and central nervous system mechanisms or indirectly through lifestyle factors, health behaviors, illness cognitions, and disease management, including medication adherence and trigger avoidance. The recent decade has witnessed surging interest in behavioral interventions that target the various pathways of influence. Among these, self-management training, breathing training, and exercise or physical activation programs have proved particularly useful, whereas other essential or promising interventions, such as smoking cessation, dietary programs, perception and biofeedback training, and suggestive or expressive psychotherapy, require further, more rigorous evaluation. Given the high comorbidity with anxiety and mood disorders, further evaluation of illness-specific cognitive behavior therapy is of particular importance. Progress has also been made in devising community-based and culturally tailored intervention programs.

CONCLUSION

In concert with an essential medication treatment, behavioral medicine treatment of asthma is moving closer toward an integrated biopsychosocial approach to disease management.

Airway responsiveness to psychological processes in asthma and health

Psychosocial factors have been found to impact airway pathophysiology in respiratory disease with considerable consistency. Influences on airway mechanics have been studied particularly well. The goal of this article is to review the literature on airway responses to psychological stimulation, discuss potential pathways of influence, and present a well-established emotion-induction paradigm to study airway obstruction elicited by unpleasant stimuli. Observational studies have found systematic associations between lung function and daily mood changes. The laboratory-based paradigm of bronchoconstrictive suggestion has been used successfully to elicit airway obstruction in a substantial proportion of asthmatic individuals. Other studies have demonstrated modulation of airway responses to standard airway challenges with exercise, allergens, or pharmacological agents by psychological factors. Standardized emotion-induction techniques have consistently shown airway constriction during unpleasant stimulation, with surgery, blood, and injury stimuli being particularly powerful. Findings with various forms of stress induction have been more mixed. A number of methodological factors may account for variability across studies, such as choice of measurement technique, temporal association between stimulation and measurement, and the specific quality and intensity of the stimulus material, in particular the extent of implied action-orientation. Research has also begun to elucidate physiological processes associated with psychologically induced airway responses, with vagal excitation and ventilatory influences being the most likely candidate pathways, whereas the role of specific central nervous system pathways and inflammatory processes has been less studied. The technique of emotion-induction using films has the potential to become a standardized challenge paradigm for the further exploration of airway hyperresponsiveness mediated by central nervous system processes.

Airway constriction in asthma during sustained emotional stimulation with films

BACKGROUND

Individuals with asthma have been shown to respond to unpleasant stimuli with bronchoconstriction, but little is known about the time course of responding during sustained emotional stimulation and whether it varies with patients' experience.

OBJECTIVE

To examine the time course of oscillatory resistance (R(os)) during emotionally evocative films in 15 asthma patients and 14 healthy controls.

METHODS

Participants viewed unpleasant, surgery, and neutral films, each ranging 3-5min in duration. R(os) and the respiratory pattern (respiration rate, tidal volume, minute ventilation) were monitored continuously. Following each film, participants rated their affective response and symptoms. The time course of R(os) during films was explored using multilevel modeling.

RESULTS

Compared to neutral film sequences, unpleasant films (including those with surgery scenes) elicited a uniform pattern of initial increases in R(os) with peaks within the first 1-2min, followed by a gradual decline. Increases were more pronounced in asthma and during surgery films. Including additional respiratory parameters as time-varying covariates did not affect the temporal course of R(os) change. The rate of decline in R(os) (after the initial increase) was less in participants who experienced greater arousal and in patients who reported more shortness of breath. Patients more susceptible to psychological triggers in daily life showed slower rates of decline in R(os).

CONCLUSION

The temporal course of bronchoconstriction to unpleasant stimulation is highly uniform in asthma, with strong constriction in early stages of stimulation. More sustained constriction in emotion-induced asthma could be a risk factor for developing asthma exacerbation in daily life.

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.

Airway response to emotion- and disease-specific films in asthma, blood phobia, and health

Earlier research found autonomic and airway reactivity in asthma patients when they were exposed to blood-injection-injury (BII) stimuli. We studied oscillatory resistance (R(os)) in asthma and BII phobia during emotional and disease-relevant films and examined whether muscle tension counteracts emotion-induced airway constriction. Fifteen asthma patients, 12 BII phobia patients, and 14 healthy controls viewed one set of negative, positive, neutral, BII-related, and asthma-related films with leg muscle tension and a second set without. R(os), ventilation, cardiovascular activity, and skin conductance were measured continuously. R(os) was higher during emotional compared to neutral films, particularly during BII material, and responses increased from healthy over asthmatic to BII phobia participants. Leg muscle tension did not abolish R(os) increases. Thus, the airways are particularly responsive to BII-relevant stimuli, which could become risk factors for asthma patients.

Airway response to emotional stimuli in asthma: the role of the cholinergic pathway

In asthma, airways constrict in response to emotion and stress, but underlying mechanisms, potential extrathoracic contributions, and associations with airway pathophysiology have not been elucidated. We therefore investigated the role of the cholinergic pathway in emotion-induced airway responses in patients with asthma and the association of these responses with airway pathophysiology. Patients with asthma (n=54) and healthy participants (n=25) received either 40 microg ipratropium bromide or a placebo in a double-blind double-dummy cross-over design in two laboratory sessions with experimental emotion induction. Stimuli were preevaluated films and pictures of pleasant, unpleasant, and neutral quality. Respiratory resistance and reactance at 5 and 20 Hz were measured continuously before and during presentations, together with respiration by impedance plethysmography and end-tidal PCO2 by capnometry. In addition, measures of airway inflammation (fraction of exhaled nitric oxide), airway hyperreactivity (methacholine challenge), and reversibility of obstruction were obtained. Respiratory resistance at 5 and 20 Hz increased during unpleasant stimuli in asthma patients. This response was blocked by ipratropium bromide and was not substantially associated with asthma severity, airway inflammation, hyperreactivity and reversibility, or pattern of ventilation and PCO2. Under the placebo condition, changes in resistance during unpleasant films were positively correlated with patients' reports of psychological asthma triggers. In conclusion, airway constriction to unpleasant stimuli in asthma depends on an intact cholinergic pathway, is largely due to the central airways, and is not substantially associated with other indicators of airway pathology. Its link to the perceived psychological triggers in patients' daily lives suggests a physiological basis for emotion-induced asthma.

The effects of paced breathing on respiratory resistance are minimal in healthy individuals

Paced breathing has been criticized for its presumed influences on autonomic and respiratory regulation, among that on respiratory resistance. It has been speculated that excessive pulmonary stretch receptor activation through high tidal volume (V(T)) would be the mechanism underlying such influences. However, the idea of airway dilation by paced breathing has remained untested. We analyzed inspiratory and expiratory resistance measured by forced oscillations in 26 healthy participants during baseline and two paced breathing conditions, regular pacing with instructions to alter rate only and pacing with additional instructions to alter volume randomly throughout the task. In each condition, four 3-min paced breathing trials at 8, 10.5, 13, and 18 breaths/min were administered. Despite pronounced changes in respiration rates and V(T) across pacing trials, neither inspiratory nor expiratory resistance were changed significantly under the regular paced breathing condition. A small reduction in resistance was only observed under conditions of variable volume at 18 breaths/min. Thus, regular paced breathing at different speeds across a range of naturally occurring breathing frequencies has only minimal effects on resistance of the airway passages.

Body awareness: construct and self-report measures

Objectives

Heightened body awareness can be adaptive and maladaptive. Improving body awareness has been suggested as an approach for treating patients with conditions such as chronic pain, obesity and post-traumatic stress disorder. We assessed the psychometric quality of selected self-report measures and examined their items for underlying definitions of the construct.

Data sources

PubMed, PsychINFO, HaPI, Embase, Digital Dissertations Database.

Review methods

Abstracts were screened; potentially relevant instruments were obtained and systematically reviewed. Instruments were excluded if they exclusively measured anxiety, covered emotions without related physical sensations, used observer ratings only, or were unobtainable. We restricted our study to the proprioceptive and interoceptive channels of body awareness. The psychometric properties of each scale were rated using a structured evaluation according to the method of McDowell. Following a working definition of the multi-dimensional construct, an inter-disciplinary team systematically examined the items of existing body awareness instruments, identified the dimensions queried and used an iterative qualitative process to refine the dimensions of the construct.

Results

From 1,825 abstracts, 39 instruments were screened. 12 were included for psychometric evaluation. Only two were rated as high standard for reliability, four for validity. Four domains of body awareness with 11 sub-domains emerged. Neither a single nor a compilation of several instruments covered all dimensions. Key domains that might potentially differentiate adaptive and maladaptive aspects of body awareness were missing in the reviewed instruments.

Conclusion

Existing self-report instruments do not address important domains of the construct of body awareness, are unable to discern between adaptive and maladaptive aspects of body awareness, or exhibit other psychometric limitations. Restricting the construct to its proprio- and interoceptive channels, we explore the current understanding of the multi-dimensional construct and suggest next steps for further research.

Perceived triggers of asthma: evaluation of a German version of the Asthma Trigger Inventory

BACKGROUND AND OBJECTIVE

Patients' perception of asthma triggers has been explored in a largely unstructured fashion in the past. Therefore, we developed the Asthma Trigger Inventory (ATI), a questionnaire that allows for a psychometrically valid measurement of patients' perceived asthma triggers. Here we evaluate a German language version of the ATI and studied the relationship of subscales with self-reported health status, health care use, psychopathology, and results of allergy skin testing.

METHOD

Data were obtained from 370 asthma patients recruited from the community, primary care, and in-patient asthma treatment and education.

RESULTS

Analysis revealed a five-factor structure that largely confirmed results with the English original. Reliability was good to satisfactory (Cronbach's alpha=0.77-0.89) for allergy, exercise, air pollution/irritants, infection, and psychological trigger subscales. In hierarchical regression analysis adjusting for demographics and asthma severity, asthma patients with stronger non-allergic triggers showed less physical and mental well-being and more asthma-related health care use. Psychological triggers showed unique associations with anxious and depressed mood. Pollen and animal allergen scores of the ATI were significantly related to skin test results for relevant allergens. Non-allergic but not allergic triggers showed substantial associations with asthma control.

CONCLUSION

The German version of the ATI reliably measures asthma patients' trigger perceptions. Non-specific asthma triggers exert a greater burden on patients' well-being and primary health care use.

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.

The asthma trigger inventory: validation of a questionnaire for perceived triggers of asthma

BACKGROUND

Asthma patients' perceptions of triggers have been explored in a largely unstructured fashion in the past. We therefore developed and validated a questionnaire of commonly perceived asthma triggers.

METHODS

Two hundred forty-seven primary care patients with asthma filled in an asthma trigger survey together with questionnaires on demographics, asthma-relevant information, perceived control of asthma, and general health status. Factor structure of the item pool and psychometric properties of trigger subscales were evaluated. We also investigated the relationship between allergen or psychological trigger reports and allergy skin test response or respiratory impedance during emotional film viewing, respectively.

RESULTS

Principal component analysis yielded six factors that were thematically associated with psychology, animal allergens, pollen allergens, physical activity, infection, and air pollution/irritants. Subscales showed good internal consistencies and low to moderately positive intercorrelations. Psychological triggers were consistently associated with less favorable health status, a reduced perception of asthma control, and greater medical treatment utilization. Animal allergen scores correlated positively with skin test responses to animal allergens. Respiratory impedance increases during emotional film clips were positively correlated with the psychological trigger subscale.

CONCLUSION

The questionnaire is a reliable measure of commonly perceived asthma triggers. Aspects of patients' trigger reports reflect actual reactivity to specific trigger factors.

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.

Airways, respiration, and respiratory sinus arrhythmia during picture viewing

Emotional stimuli can cause airway constriction; however, it is uncertain whether a dimensional or categorical model of emotion can better describe airway changes. Also, little is known about the affective modulation of respiration and vagal activity, which can influence airway tone. We studied changes in oscillatory resistance (Ros), respiration, and respiratory sinus arrhythmia (RSA) in asthmatics and controls during viewing of affective pictures eliciting anxiety, depression, disgust, happiness, contentment, erotic tension, or neutral affect. Ros, respiration, cardiac activity, and self-report were measured during picture presentations. Ros increased monotonically with picture unpleasantness mainly due to disgust pictures. RSA and respiratory timing parameters were particularly sensitive to erotic pictures. Differences between asthmatics and controls were minimal, suggesting that airway responses to unpleasant pictures are not specific to asthma.

Current perspectives on symptom perception in asthma: a biomedical and psychological review

Symptom perception in patients with asthma is often inadequate. Patients may fail to perceive serious airway obstruction or suffer from breathlessness without objective cause. These extremes are associated with fatal asthma and excessive use of medicines, respectively. This article covers symptom perception in a multidisciplinary perspective. A presentation of current definitions and methods for studying symptom perception in asthma is followed by a summary of theories on the origin of breathlessness. Next, biomedical and psychological factors influencing symptom perception are examined. Preliminary biomedical research emphasizes neural pathway impairment, but causal factors remain inconclusive, particularly regarding the overperception of symptoms. Psychological studies suggest that the accuracy of symptom perception is influenced by (a) competition between asthmatic and nonasthmatic sensory information, (b) negative emotions, and (c) acquired response tendencies (e.g. habituation to symptoms, repression of symptoms, selective perception, and false interpretation of symptoms). These factors may favor either blunted perception or overperception. Empirical data in support of psychological factors are still insufficient. Methodological problems and procedures to improve symptom perception are discussed.

Advancing the science of perceptual accuracy in pediatric asthma and diabetes

OBJECTIVES

To review research on perceptual accuracy in pediatric asthma and diabetes and to provide recommendations for future research efforts and clinical applications of the construct in these populations.

METHODS

A literature search was conducted using Medline and PsychInfo databases as well as the bibliographies of relevant articles.

RESULTS

Children and adolescents with asthma or diabetes evidence considerable variability in perceptual accuracy and frequently make clinically relevant errors that have the potential to affect self-management behavior.

CONCLUSIONS

Recommendations for future research include studying distinct types of perceptual errors, empirically supporting the relationship between perceptual accuracy and relevant outcomes, identifying factors related to perceptual inaccuracy, and conducting longitudinal research and intervention studies. Recommendations for applying the construct in clinical practice include adopting an individualized approach to symptoms to guide patient education and management, identifying patients prone to making clinically relevant errors, and developing and implementing interventions to improve accuracy.

Probing the psychophysiology of the airways: physical activity, experienced emotion, and facially expressed emotion

This article reviews research on airway reactivity in health and asthma within a psychophysiological context, including the effects of physical activity, emotion induction, and manipulation of facial expression of emotion. Skeletal muscle activation leads to airway dilation, with vagal withdrawal being the most likely mechanism. Emotional arousal, in particular negative affect, leads to airway constriction, with evidence for a vagal pathway in depressive states and ventilatory contributions in positive affect. Laboratory-induced airway responses covary with reports of emotion-induced asthma and with lung function decline during negative mood in the field. Like physical activity, facial expression of emotion leads to airway dilation. However, these effects are small and less consistent in posed emotional expressions. The mechanisms of emotion-induced airway responses and potential benefits of emotional expression in asthma deserve further study.

Automatic Negative Evaluation of Suffocation Sensations in Individuals With Suffocation Fear

The current study tested whether "suffocation sensations" (respiratory loads) are automatically evaluated in a negative way by people fearing these sensations. It was found that, after having been primed with a slight respiratory load, participants with high suffocation fear (n=15) reacted more quickly to suffocation words and more slowly to positive words than participants with low suffocation fear (n=21). However, the effect was present only in participants who had noticed the primes. The findings are relevant to the cognitive model of panic disorder because automatic negative appraisal of sensations may play a role in initiating a panic attack.

Behavioral interventions in asthma: biofeedback techniques

OBJECTIVES

Biofeedback techniques have long been recommended as an adjunctive treatment for bronchial asthma. Techniques that target lung function directly, or indirectly by altering facial muscle tension, heart rate, heart rate variability (HRV) or inspiratory volume together with accessory muscle tension, have been proposed. We review evidence for the effectiveness of these biofeedback interventions and discuss the psychophysiological rationale behind individual techniques.

METHOD

Controlled studies of biofeedback in asthma were retrieved using relevant search engines and reference lists of published articles. Effect sizes comparing intervention with control groups were calculated where appropriate.

RESULTS

Most of the studies suffer from methodological inadequacies or poor reporting of methods and results. Interventions targeting respiratory resistance directly have yielded only small and inconsistent changes in lung function and are difficult to implement without producing dynamic hyperinflation. Biofeedback-assisted facial muscle relaxation as an indirect intervention has yielded mixed results across studies, with only half of the studies showing significant albeit very small and clinically irrelevant improvements in lung function. The underlying physiological assumptions of the technique are questionable in the light of current knowledge of respiratory physiology. For other indirect techniques, only preliminary evidence of small effects is available.

CONCLUSION

Currently, there is little good evidence that biofeedback techniques can contribute substantially to the treatment of asthma.

Airway response of healthy individuals to affective picture series

We studied the effects of viewing pictures in three series of homogeneous affects on respiratory resistance. Results from prior studies had been equivocal with respect to modulation of resistance by affective valence or arousal. Forty-two healthy participants viewed three series of affective slides preselected for global categories of positive, neutral and negative valence. Oscillatory resistance (R(os)), time, volume and flow parameters of respiration, cardiac interbeat-interval, respiratory sinus arrhythmia, and skin conductance were measured throughout the picture series, and individual pictures were rated in pleasure, arousal and interest. During the slide presentation, R(os) increased with decreasing picture valence. Other physiological parameters did not parallel these changes. R(os) changes were restricted to the expiratory portion of the breathing cycle, thus suggesting a contribution of upper airway sites to the response. It is concluded that R(os) is modulated by affective valence when pictures are selected in global categories of positive, neutral and negative affect. Observed airway responses are probably less informative with respect to affect-induced exacerbation in lower airway disease.

Improved Methodology for Threshold Detection Studies in Asthmatic Children

Abstract This paper reports the differences between two methodologies for threshold detection of added resistive loads in children and adolescents. The first-generation apparatus utilized a series of laminar flow screens to present various total resistances, while in the second generation the apparatus utilized a servo-controlled cone that occluded an aperture to varying degrees. Protocol modifications in the second generation methodology included forced choice, attentional enhancements, and larger increments of added resistance. Two studies conducted 2 years apart provided data on the first and second generations of methodology. All participants in Study 1 (N = 33) and Study 2 (N = 33) were children with asthma. Subjects were matched for both age and asthma severity. Results showed the methodologic improvements in the second generation to be significant. Tracking and random thresholds were achieved by 85% and 82% of the subjects in Study 2 compared to 76% and 42% in Study 1, respectively. The correlation between the mean tracking and random thresholds was .40 in Study 2 compared to a statistically insignificant result in Study 1, indicating improved reliability. Raw thresholds were correlated with intrinsic resistance in both studies (r = .29-.88), supporting the use of Weber's Law in resistive loading studies of children. Results using the second generation methodologic improvements demonstrate that children as young as age 7 can complete resistance loading protocols. Standard methodology will enhance the comparability between studies.