Multidisciplinary management of inducible laryngeal obstruction and breathing pattern disorder

We provide an overview of the assessment and management of inducible laryngeal obstruction and breathing pattern disorder. We highlight the multidisciplinary team members involved and their essential roles within a complex breathlessness service. We discuss treatments initiated by physiotherapy and speech and language therapy, the importance of joint working, and discuss the high incidence of comorbidities and the association with other respiratory disorders.

Educational aims

Inducible laryngeal obstruction and breathing pattern disorder are common causes of breathlessness.Inducible laryngeal obstruction is an inappropriate, transient, reversible narrowing of the laryngeal area that causes breathlessness and laryngeal symptoms.Breathing pattern disorder is an alteration in the normal biomechanical patterns of breathing that results in intermittent or chronic symptoms, which may be respiratory and/or non-respiratory.People with inducible laryngeal obstruction or breathing pattern disorder often have other comorbidities that will also need addressing.Multidisciplinary assessment and treatment is essential for comprehensive workup and holistic care.Timely assessment and diagnosis can prevent unnecessary medication use and hospital admissions and facilitate effective management of the condition using reassurance, advice, education, breathing retraining and vocal exercises.

Assessment of functional respiratory complaints and related factors in people with hypermobile Ehlers-Danlos syndrome: Cross-sectional study

BACKGROUND

Hypermobile Ehlers-Danlos Syndrome (hEDS) is the most common type of EDS. Apart from joint symptoms, people with hEDS have systemic manifestations as a chronic modification of the breathing pattern (functional respiratory complaints (FRCs)) and mental disorders. However, the prevalence of FRCs, and its relationship with mental disorders, have not yet been estimated for this population.

OBJECTIVES

To assess the FRCs, central sensitization, disease perception, depression, and anxiety in people with hEDS from Belgium; and to identify the clustering of FRCs and determine any association with the characteristics assessed for this sample.

METHODS

This cross-sectional study assessed socio-demographic characteristics, Nijmegen questionnaire (NQ), Central Sensitization Inventory (CSI), Brief Illness Perception Questionnaire, and the Hospital Anxiety and Depression Scale (HADS) in people with hEDS from Belgium. A two-step cluster analysis was performed to identify clusters according to NQ, and to understand how the other questionnaires are grouped among these clusters.

RESULTS

The Spearman correlation coefficients showed that all the outcomes were significantly and positively correlated with each other (p<0.05). Furthermore, 84.9% of the sample had symptoms suggestive of FRCs, and 54.3% had probable anxiety. Three clusters were grouped (no FRCs, mild FRCs, and severe FRCs), with NQ, HADS-D and CSI-part A being the variables that contributed the most. People from cluster of severe FRCs got the worst scores for all the questionnaires.

CONCLUSION

FRCs, central sensitization, depression, and anxiety are prevalent comorbidities in people with hEDS. Moreover, those people with FRCs had worse results in the investigated parameters, with depression being the variable that contributed the most to the clusters of FRCs. Consequently, investigating mechanisms for these co-occurring symptom profiles may improve our understanding of pathogenesis and indicate new management strategies to alleviate these symptoms and lead to the development of more effective care for persons with hEDS.

Immediate Effects of Whole-Body versus Local Dynamic Electrostimulation of the Abdominal Muscles in Healthy People Assessed by Ultrasound: A Randomized Controlled Trial

Dynamic electrostimulation consists of the application of local or global electrostimulation together with physical exercise. This study aimed to investigate the immediate effects of a dynamic electrostimulation session on the thickness of the abdominal musculature, inter-rectus distance, heart rate, blood pressure, and body temperature, and to identify possible differences in its form of application. A total of 120 healthy participants were divided into three groups: the whole-body electrostimulation group, the local electrostimulation group, and the control group without electrical stimulation. All groups performed a single session with the same dynamic exercise protocol. Muscle thickness and inter-rectus distance were evaluated ultrasonographically using the Rehabilitative Ultrasound Imaging technique both at rest and in muscle contraction (the active straight leg raise test) to find the post-intervention differences. The results showed significant differences in immediate post-intervention heart rate, with a smaller increase in the local electrostimulation group compared to the control and whole-body electrostimulation groups. No significant differences were identified between the groups after the interventions in the rest of the variables analyzed. Therefore, a local application, with the same effects as a global application on the abdominal musculature, has fewer contraindications, which makes its use more advisable, especially in populations with cardiorespiratory disorders, for which more research is needed.

Psycho-demographic profile in severe asthma and effect of emotional mood disorders and hyperventilation syndrome on quality of life

Background

Severe asthma affects a small population but carries a high psychopathological risk. Therefore, the psychodemographic profile of these patients is of interest. A substantial prevalence of anxiety, depression, alexithymia and hyperventilation syndrome in severe asthma is known, but contradictory results have been observed. These factors can also affect patients’ quality of life. For this reasons, our purpose is to evaluate the psychodemographic profile of patients with severe asthma and assess the prevalence of anxiety, depression, alexithymia and hyperventilation syndrome and their impact on the quality of life of patients with severe asthma.

Methods

A cross-sectional study of 63 patients with severe asthma. Their psychodemographic profile was evaluated using the Hospital Anxiety and Depression Scale (HADS), Toronto Alexithymia Scale (TAS-20), Nijmegen questionnaire and Asthma Control Test (ACT) to determine the state of anxiety and depression, alexithymia, hyperventilation syndrome and control of asthma, respectively. Quality of life was assessed with the Mini Asthma Quality of Life Questionnaire (Mini-AQLQ).

Results

The mean age was 60 ± 13.6 years. Personal psychopathological histories were found in 65.1% of participants, and 8% reported previous suicidal attempts. The rate of anxiety and/or depression (HADS ≥ 11) was 68.3%. These patients present higher scores on the TAS-20 (p < 0.001) for the level of dyspnea (p = 0.021), and for emotional function (p = 0.017) on the Mini-AQLQ, compared with patients without anxiety or depression. Alexithymia (TAS-20 ≥ 61) was observed in 42.9% of patients; these patients were older (p = 0.037) and had a higher HADS score (p = 0.019) than patients with asthma without alexithymia. On the other hand, patients with hyperventilation syndrome (Nijmegen ≥ 23) scored higher on the HADS (p < 0.05), on the Mini-AQLQ (p = 0.002) and on the TAS-20 (p = 0.044) than the group without hyperventilation syndrome. Quality of life was related to anxiety-depression symptomatology (r =  − 0.302; p = 0.016) and alexithymia (r =  − 0.264; p = 0.036). Finally, the Mini-AQLQ total score was associated with the Nijmegen questionnaire total score (r =  − 0.317; p = 0.011), and the activity limitation domain of the Mini-AQLQ correlated with the ACT total score (r = 0.288; p = 0.022).

Conclusions

The rate of anxiety, depression, alexithymia and hyperventilation syndrome is high in patients with severe asthma. Each of these factors is associated with a poor quality of life.

Fibromyalgia in Iraqi patients with asthma and its impact on asthma severity and control

Background

Fibromyalgia (FM) is common with significant impact on patients quality of life. Limited reports on coexistence of FM with asthma.

Objectives

To assess the prevalence of FM in asthmatic patients and its impact on asthma severity and control.

Patients and methods

This case-control study included 103 patients with asthma and 102 apparently healthy controls matched in age and sex. Sociodemographic and clinical characteristics of FM and controls were recorded. FM was diagnosed according to the 2016 revision of American College of Rheumatology criteria. Asthma diagnosis and severity were performed by the pulmonologist according to Global Initiative for Asthma (GINA) guidelines and asthma control was assessed by Asthma Control Test (ACT) score.

Results

The mean age of asthmatic patients was 41.1 ± 12.7 years and for controls was 39.8 ± 12 years (p = 0.453). Females were more prevalent in asthmatic patients and controls although statistically were not significant (p-value = 0.532). Prevalence of FM was significantly more in asthmatic patients compared to controls [18 (17.6%) vs 7 (6.8%), p = 0.018] and asthmatic patients had three folds risk of having FM (ranging from 1.2 to 7.4 times. FM increased the risk of severe asthma by 4.91 folds (P < 0.005). Also, only FMS and glucocorticoids were significant independent predictor of having poor asthma control. FM was significantly and negatively correlated with low ACT score (β standardized regression coefficient = −0.291, p = 0.005).

Conclusions

fibromyalgia was common in asthmatic patients and was significantly associated with more severe and poorly controlled asthma.

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Fibromyalgia (FM) was more common in asthmatic patients compared with controls.

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FM was significantly associated with more severe and poorly controlled asthma.

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Breathing training programs may be useful management in asthmatic patients with FM.

Dysfunctional Breathing in Children and Adults With Asthma

Asthma occurs across the life course. Its optimal treatment includes the use of personalized management plans that recognize the importance of co-morbidities including so-called "dysfunctional breathing." Such symptoms can arise as a result of induced laryngeal obstruction (ILO) or alterations in the mechanics of normal breathing called breathing pattern disorders. Whilst these two types of breathing abnormalities might be related, studies tend to focus on only one of them and do not consider their relationship. Evidence for these problems amongst childhood asthmatics is largely anecdotal. They seem rare in early childhood. Both types are more frequently recognized in the second decade of life and girls are affected more often. These observations tantalizingly parallel epidemiological studies characterizing the increasing prevalence and severity of asthma that also occurs amongst females after puberty. Exercise ILO is more common amongst adolescents and young adults. It should be properly delineated as it might be causally related to specific treatable factors. More severe ILO occurring at rest and breathing pattern disorders are more likely to be occurring within a psychological paradigm. Dysfunctional breathing is associated with asthma morbidity through a number of potential mechanisms. These include anxiety induced breathing pattern disorders and the enhanced perception of subsequent symptoms, cooling and drying of the airways from hyperventilation induced hyperresponsiveness and a direct effect of emotional stimuli on airways constriction via cholinergic pathways. Hyperventilation is the most common breathing pattern disorder amongst adults. Although not validated for use in asthma, the Nijmegen questionnaire has been used to characterize this problem. Studies show higher scores amongst women, those with poorly controlled asthma and those with psychiatric problems. Evidence that treatment with breathing retraining techniques is effective in a primary care population including all types of asthmatics suggests the problem might be more ubiquitous than just these high-risk groups. Future challenges include the need for studies characterizing all types of dysfunctional breathing in pediatric and adult patient cohorts and clearly defined, age appropriate, interventional studies. Clinicians caring for asthmatics in all age groups need to be aware of these co-morbidities and routinely ask about symptoms that suggest these problems.

Breathing exercises for asthma

Educational aims

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

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

Summary

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

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

Key points

Asthma is frequently poorly controlled despite effective modern medication

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

Breathing exercises can improve patient-reported outcomes and psychological state

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

Factors associated with severe uncontrolled asthma and the perception of control by physicians and patients

INTRODUCTION

Despite current treatments, more than half of patients with asthma are not controlled. The objective was to evaluate the correlation between control perceived by patients and physicians, compared with control evaluated according to criteria of the Spanish Guidelines for Asthma Management (GEMA), and to investigate the factors associated with that control.

METHODS

Multicenter, cross-sectional, observational study including 343 patients with severe persistent asthma according to GEMA criteria seen in the Department of Pulmonology and Allergology. The correlation between asthma control perceived by the patient, the physician and according to clinical judgment based on the GEMA criteria was calculated, and a multivariate analysis was used to determine variables related to the perception of asthma control.

RESULTS

According to GEMA criteria, only 10.2% of patients were well controlled, 27.7% had partial control and 62.1% were poorly controlled. Both the physicians and the patients overestimated control: 75.8% and 59.3% of patients had controlled asthma according to the patient and the physician, respectively, and were not controlled according to GEMA (P<.0001). Patients with uncontrolled asthma according GEMA had higher body mass index (P=.006) and physical inactivity (P=.016). Factors associated with a perceived lack of control by both physicians and patients were: nocturnal awakenings (≥ 1 day/week), frequent use of rescue medication (≥ 5 days/week) and significant limitation in activities. Discrepant factors between physicians and patients were dyspnea and emergency room visits (patients only), FEV1 ≤ 80% and a poorer understanding of the disease by the patient (physicians only).

CONCLUSIONS

Only 10% of patients with severe asthma evaluated in this study are controlled according to GEMA criteria. Patients and physicians overestimate control and the overestimation by patients is greater. Physical inactivity and obesity are associated with a lack of control according to GEMA.

Prevalence of psychiatric disorders among patients investigated for occupational asthma: an overlooked differential diagnosis?

RATIONALE

Up to one-third of patients assessed for occupational asthma (OA) do not receive a diagnosis of OA or any other medical disorder. Although several differential diagnoses are considered (e.g., rhinitis, chronic obstructive pulmonary disease), psychiatric disorders (many with somatic complaints that mimic asthma) are rarely considered or assessed.

OBJECTIVES

To assess the prevalence of psychiatric disorders (mood and anxiety disorders and hypochondriasis) in patients suspected of having OA, and whether psychiatric morbidity increases the risk of not receiving any medical diagnosis.

METHODS

A total of 219 consecutive patients (57% male; mean age, 41.8 ± 11.1 yr) underwent sociodemographic and medical history interviews on the control or specific inhalation testing day of their OA evaluation. The Primary Care Evaluation of Mental Disorders was used to assess mood and anxiety disorders, and the Whiteley Hypochondriasis Index was used to assess hypochondriasis.

MEASUREMENTS AND MAIN RESULTS

A total of 26% (n = 50) of patients had OA; 25% (n = 48) had asthma or work-exacerbated asthma; 14% (n = 28) had another inflammatory disorder; 13% (n = 26) had a noninflammatory disorder; and 22% (n = 44) did not receive any medical diagnosis. A total of 34% (n = 67) of patients had a psychiatric disorder: mood and anxiety disorders affected 29% (n = 57) and 24% (n = 46) of the sample, respectively, and 7% (n = 12) had scores on the Whiteley Hypochondriasis Index indicating hypochondriasis. Hypochondriasis, but not mood or anxiety disorders, was associated with an increased risk of not receiving any medical diagnosis (adjusted odds ratio, 3.92; 95% confidence interval, 1.18-13.05; P = 0.026).

CONCLUSIONS

Psychiatric morbidity is common in this population, and hypochondriasis may account for a significant proportion of the "undiagnosable" cases of patients who present for evaluation of OA.

[Prevalence of chronic hyperventilation syndrome in children and teenagers]

OBJECTIVE

The aim of this study was to investigate the prevalence of hyperventilation syndrome in the general population of children and teenagers from the Île-de-France region (France).

METHODS

Three hundred children and teenagers (170 girls and 130 boys, aged 1 to17 years) were included in the study. To evaluate the probability of hyperventilation syndrome, we asked the children and teenagers to complete the Hyperventilation Syndrome Ambroise-Paré Enfant (SHAPE) questionnaire. The frequency of occurrence of the signs was evaluated by the child himself or herself with or without parental help. Children and teenagers with a score of 25 or over were considered to have hyperventilation syndrome.

RESULTS

Sixty-three out of 300 questionnaires with a score of 25 or over revealed the presence of hyperventilation syndrome: 21% of the population evaluated. Among those surveyed, 42 were girls and 21 boys: 24.7 and 16.2%, respectively. The 280 questionnaires filled out among the non-asthmatics showed that 52 were positive (18.6%), while the positivity rate in the asthma group amounted to 55%.

CONCLUSION

Although the diagnostic criteria for hyperventilation syndrome remains contested, this study shows that the disorder is real and frequent.

Factors related with the higher percentage of hospitalizations due to asthma amongst women: the FRIAM study

INTRODUCTION

The reason why there is a higher hospitalization rate due to asthma exacerbations amongst women is unclear. The objective of this study is to explore the possible causes that may explain this fact.

METHODS

A multi-center, prospective study including asthma patients hospitalized in the pulmonary medicine departments during a two-year period. By means of a questionnaire, the following data were collected: demographic characteristics and treatment compliance, anxiety-depression, hyperventilation and asthma control, both prior to and during the hospitalization.

RESULTS

183 patients were included, 115 (62.84%) of whom were women. The women were older (52.4 ± 18.3/43.4 ± 18.7; P=.02), were more frequently prescribed inhaled corticosteroids (63.2%/47.1%; P=.03) and had a higher rate of hyperventilation syndrome (57.3/35.9; P=.02) and a longer mean hospital stay (7.3 ± 3.4/5.9 ± 3.6; P=.02). The percentage of smokers among the women was lower (21.2%/38.8%; p=0.01) and the FEV(1) was lower at admittance (58.2% ± 15.9/67.5% ± 17.4; P=.03). In the 40 to 60-year-old age range, an association was demonstrated between being female and the 'previous hospitalizations' variable (OR, 16.1; 95% CI, 1.6-156.7); sex and obesity were also independently associated (OR, 4.8; 95% CI, 1.06-22).

CONCLUSIONS

In this cohort, the rate of hospitalization for asthma was higher in women than in men. Being a woman between the ages of 40 and 60 is associated with previous hospitalizations and is a risk factor for asthma-related hospitalization. This situation could partially be explained by the hormonal changes during menopause, where polyposis and obesity are independent risk factors.

Reliability and validity of a short version of the STAI anxiety measurement scale in respiratory patients

BACKGROUND

There is comorbidity between respiratory disease and anxiety. In order to measure the anxiety of hospitalized patients it is necessary to use reliable and valid, and preferably short questionnaires.

OBJECTIVE

To analyze the reliability and validity of a shortened version of the state subscale of the “State-Trait Anxiety Inventory (STAI)” in respiratory patients.

PATIENTS AND METHODS

A total of 103 respiratory patients admitted to the respiratory ward between February of 2009 and February of 2010 were non-consecutively selected. They answered two questionnaires: the Spanish version of the STAI-state and a short version consisting of 7 items. Sociodemographic and clinical variables of the patients were also obtained. The internal consistency, and convergent and construct validity of the short scale were analyzed.

RESULTS

The short scale did not have floor/ceiling effect, the α-Cronbach was acceptable (0.89), and correlated positively (r = 0.90; P = .01) and also maintained the factorial structure of the original scale (half anxiety-present items and half anxiety-absent items).

CONCLUSIONS

The short version of the state subscale of the STAI has showed good metric properties in hospitalized respiratory patients.

Psychological profile of patients with bronchial asthma and functional dyspnea: a comparison with a non-asthmatic population and impact on the disease

BACKGROUND

Few studies have analysed the relationship between anxiety and alexithymia with functional dyspnea (FD) and its impact on quality of life and asthma control. The aim of this study was to assess the prevalence of DD in asthma, its impact on quality of life and asthma control and its relationship with anxiety and alexithymia.

PATIENTS AND METHODS

We performed a cross-sectional study of 264 asthmatic patients and 111 controls. Both groups completed the following questionnaires: quality of life (AQLQ), alexithymia (TAS-20), anxiety (STAI) and FD (Nijmegen). In asthmatics were evaluated: asthma severity, dyspnoea, exacerbation and control of the disease (ACT test).

RESULTS

38% of asthmatics and 5.5% of non-asthmatics had FD. Asthmatics had more anxiety and were more alexithymic. Asthmatics with FD had significantly more anxiety, more alexithymia, poor control of asthma, more exacerbations and poorer quality of life, that asthma without DD. Asthmatics with an ACT<19, a score >3 in the emotion subscale of the AQLQ, who were being treated for anxiety and scored >19 on the alexithymia subscale that assesses difficulty in identifying emotions, showed ORs for FD of 2.6 (1.1-5.9), 6.8 (2.9-15.8), 4.4 (1.9-9.8) and 3.3 (1.5-7), respectively. A predictive model of FD was constructed.

CONCLUSIONS

We demonstrated the close relationship between anxiety, alexithymia and DD in asthmatics, as well as the significant impact of FD on the control and quality of life of this asthmatics.

The utility of cardiopulmonary exercise testing in difficult asthma

BACKGROUND

Unexplained persistent breathlessness in patients with difficult asthma despite multiple treatments is a common clinical problem. Cardiopulmonary exercise testing (CPX) may help identify the mechanism causing these symptoms, allowing appropriate management.

METHODS

This was a retrospective analysis of patients attending a specialist-provided service for difficult asthma who proceeded to CPX as part of our evaluation protocol. Patient demographics, lung function, and use of health care and rescue medication were compared with those in patients with refractory asthma. Medication use 6 months following CPX was compared with treatment during CPX.

RESULTS

Of 302 sequential referrals, 39 patients underwent CPX. A single explanatory feature was identified in 30 patients and two features in nine patients: hyperventilation (n = 14), exercise-induced bronchoconstriction (n = 8), submaximal test (n = 8), normal test (n = 8), ventilatory limitation (n = 7), deconditioning (n = 2), cardiac ischemia (n = 1). Compared with patients with refractory asthma, patients without "pulmonary limitation" on CPX were prescribed similar doses of inhaled corticosteroid (ICS) (median, 1,300 μg [interquartile range (IQR), 800-2,000 μg] vs 1,800 μg [IQR, 1,000-2,000 μg]) and rescue oral steroid courses in the previous year (median, 5 [1-6] vs 5 [1-6]). In this group 6 months post-CPX, ICS doses were reduced (median, 1,300 μg [IQR, 800-2,000 μg] to 800 μg [IQR, 400-1,000 μg]; P < .001) and additional medication treatment was withdrawn (n = 7). Patients with pulmonary limitation had unchanged ICS doses post CPX and additional therapies were introduced.

CONCLUSIONS

In difficult asthma, CPX can confirm that persistent exertional breathlessness is due to asthma but can also identify other contributing factors. Patients with nonpulmonary limitation are prescribed inappropriately high doses of steroid therapy, and CPX can identify the primary mechanism of breathlessness, facilitating steroid reduction.

[Evolution over time in over perceivers of dyspnea in asthma]

OBJECTIVE

In previous studies we identified a subgroup of patients whose perception of breathlessness was exaggerated during acute bronchoconstriction and who were termed "over perceivers" or "hyperperceivers". In this study we aimed to determine whether such over perception is sporadic or stable over time. We also examined whether there is an association between over perception of dyspnea and hyperventilation syndrome.

PATIENTS AND METHODS

The subjects were 22 stable asthmatics (11 men, 11 women) who had been over perceivers of dyspnea in a study 9 years earlier. After a medical history was taken, a patient performed forced spirometry and a severity classification was made according to the criteria of the Global Initiative for Asthma (GINA). A bronchial histamine challenge was then administered to measure dose-related perception of dyspnea on a Borg scale, according to a procedure that was similar to the one used 9 years earlier by the same investigator. The patients were also asked for a subjective assessment of the severity of their asthma (scale, 0-10) and to respond to items on the Nijmegen hyperventilation questionnaire and the trait form of the State-Trait Anxiety Inventory.

RESULTS

The overall perception of severity of disease, level of anxiety, and perception of dyspnea at rest were lower after 9 years (P<.001). No change was observed in bronchial hyperresponsiveness (dose of inhaled histamine required to provoke a 20% decline in forced expiratory volume in the first second [FEV1]-PD20) or objective parameters of severity (FEV1 and GINA classification). Fourteen asthmatics (64%) were still over perceivers and the other patients had changed: 6 were normal perceivers and 2 were "poor perceivers". Only subjective perception of disease severity improved for the patients who were still over perceivers; the other patients, on the other hand, showed improvements in subjective assessments, objective ones (except PD20), and anxiety. Finally, those who remained over perceivers had higher scores for anxiety (24 vs 15; P<.05) and hyperventilation (18 vs 13; P= not significant).

CONCLUSIONS

Most over perceivers of dyspnea remain so over the years and this trait is related to anxiety. We have been unable to demonstrate an association with hyperventilation syndrome.