Hypocapnia and asthma: a mechanism for breathing retraining?

Effect of breathing re-training on end-tidal carbon-di-oxide in patients with asthma: a systematic review and meta-analysis

OBJECTIVE

The review aims to determine the effect of breathing re-training on End-tidal carbon-di-oxide (ETCO2) in patients with asthma.

DATA SOURCES

A systematic search of articles was performed in PubMed, Cochrane, PEDro, Scopus, and Ovid databases from their inception till May 2022.

STUDY SELECTIONS

Studies were included if the patients were clinically diagnosed with mild-moderate asthma. Randomized controlled trials that monitored ETCO2 as a primary or secondary outcome were included. Studies were examined for potential risk of bias using the Revised Cochrane risk of bias tool by two independent reviewers.

RESULTS

Eight articles were included. The trials used various techniques like Buteyko, Papworth, Biofeedback, and holistic approach. Quantitative analysis was conducted to examine the effects on ETCO2 at various time points. A significant large effect was seen on ETCO2 following breathing re-training post-treatment, 3 and 6 months post-intervention.

CONCLUSION

There is moderate evidence for a significant effect of breathing re-training on ETCO2 in the short and long term in patients with asthma. However, high-quality randomized controlled trials using standardized measurement of ETCO2 are required to evaluate the effects of different breathing re-training techniques.

Role of Breathing Exercises in Asthma-Yoga and Pranayama

Asthma is a chronic airway inflammatory disease that results from a complex interplay of genetic, environmental, and lifestyle factors. There is no cure for asthma, and the management is usually as per published guidelines. As in many chronic diseases conditions, various alternative or complimentary therapies have been tried. Of these, yoga and pranayama have gained wider attention in recent years. While the term yoga is a complex term encompassing eight limbs as per Patamjai in the yoga sutras, in simple terms, yoga is described as a combination of 'asana' (physical exercises) and 'pranayama' (breathing exercise). The term "asthma" has been derived from the Greek word "panting,", which indicates a rapid and shallow breathing. The main aim of yoga and pranayama in asthma is to synchronize and control breathing, thus decreasing hyperventilation. Besides this, they also decrease the stress/strain/anxiety, change in behavior, boost immunity, and improve strength/endurance of respiratory muscles that are helpful in any subject with asthma. There have been a good number of studies including clinical trials in children with asthma that have found some beneficial effects. In the present review, the physiology of yoga and pranayama, rationale for their use in children with asthma along with a summary of various studies conducted till date, have been discussed. These are followed by recommendations regarding their incorporation in the standard of care of children with asthma.

Prevalence of hyperventilation in patients with asthma

OBJECTIVE

Asthma is frequently accompanied by dysfunctional breathing of which hyperventilation has been recognized as a subtype. The prevalence of hyperventilation in stable asthma has been scantily studied using blood gas analysis. Hence, a reliable estimate of its prevalence is lacking. It is unknown whether the Nijmegen Questionnaire (NQ) is a useful screening tool for hyperventilation in asthma. Therefore, the primary aim of this study was to determine the prevalence of hyperventilation in a large sample of patients with asthma in a stable state of disease. Secondary aims were to compare the clinical characteristics between patients with and without hyperventilation, and, to examine the concurrent validity of the NQ to detect hypocapnia in patients with asthma.

METHODS

A real-world, observational, multicenter study was conducted. Capillary blood gas analysis was performed in adults with a confirmed diagnosis of stable asthma. A subset of patients completed the NQ.

RESULTS

A blood gas analysis was obtained in 1006 patients. In 17% of the patients an acute hyperventilation was found, and in another 23% a chronic hyperventilation was uncovered. Patients with a chronic hyperventilation blood gas were more often female, were younger and had a better spirometric outcomes. The NQ appeared not to correlate with PCO2.

CONCLUSION

Hyperventilation is common in patients with stable asthma. Chronic hyperventilation is more often found in females of younger age and with the best spirometric outcomes compared to patients without hyperventilation. The NQ is not a suitable screening tool for the presence of hyperventilation in stable asthmatics.

Breathing Re-Education and Phenotypes of Sleep Apnea: A Review

Four phenotypes of obstructive sleep apnea hypopnea syndrome (OSAHS) have been identified. Only one of these is anatomical. As such, anatomically based treatments for OSAHS may not fully resolve the condition. Equally, compliance and uptake of gold-standard treatments is inadequate. This has led to interest in novel therapies that provide the basis for personalized treatment protocols. This review examines each of the four phenotypes of OSAHS and explores how these could be targeted using breathing re-education from three dimensions of functional breathing: biochemical, biomechanical and resonant frequency. Breathing re-education and myofunctional therapy may be helpful for patients across all four phenotypes of OSAHS. More research is urgently needed to investigate the therapeutic benefits of restoring nasal breathing and functional breathing patterns across all three dimensions in order to provide a treatment approach that is tailored to the individual patient.

Asthma - A Disease of How We Breathe: Role of Breathing Exercises and Pranayam

To describe the role of breathing exercises or yoga and/or pranayama in the management of childhood asthma. We conducted an updated literature search and retrieved relevant literature on the role of breathing exercises or yoga and/or pranayama in the management of childhood asthma. We found that the breathing exercises or yoga and/or pranayama are generally multi-component packaged interventions, and are described as follows: Papworth technique, Buteyko technique, Yoga and/or Pranayam. These techniques primarily modify the pattern of breathing to reduce hyperventilation resulting in normalisation of CO2 level, reduction of bronchospasm and resulting breathlessness. In addition they also change the behaviour, decrease anxiety, improve immunological parameters, and improve endurance of the respiratory muscles that may ultimately help asthmatic children. We found 10 clinical trials conducted in children with asthma of varying severity, and found to benefit children with chronic (mild and moderate) and uncontrolled asthma, but not acute severe asthma. Breathing exercises or yoga and/or pranayama may benefit children with chronic (mild and moderate) and uncontrolled asthma, but not acute severe asthma. Before these techniques can be incorporated into the standard care of asthmatic children, important outcomes like quality of life, medication use, and patient reported outcomes need to be evaluated in future clinical trials.

Association of epilepsy and asthma: a population-based retrospective cohort study

Background

Epidemiologic data supporting the epilepsy–asthma association are insufficient. Therefore, we examined this association in this study.

Methods

By using claims data from the National Health Insurance Research Database (Taiwan), we executed a retrospective cohort analysis. Analysis 1 entailed comparing 150,827 patients diagnosed as having incident asthma during 1996–2013 with disease-free controls who were selected randomly during the same period, frequency matched in terms of age and sex. Similarly, analysis 2 entailed comparing 25,274 patients newly diagnosed as having epilepsy with sex- and age-matched controls who were selected randomly. At the end of 2013, we evaluated in analysis 1 the epilepsy incidence and risk and evaluated in analysis 2 the asthma incidence and risk. We applied Kaplan–Meier analysis to derive plots of the proportion of asthma-free seizures.

Results

In analysis 1, the asthma group exhibited a higher epilepsy incidence than did the control group (3.05 versus 2.26 per 1,000 person-years; adjusted hazard ratio: 1.39, 95% CI [1.33–1.45]). We also noted a greater risk of subsequent epilepsy in women and girls. In analysis 2, we determined that the asthma incidence between the control and epilepsy groups did not differ significantly; however, some age subgroups including children and individuals in their 30s had an increased risk. A negative association was found in adolescents. The Kaplan–Meier analysis revealed epilepsy to be positively associated with subsequent onset of asthma within seven years of epilepsy diagnosis.

Discussion

Asthma may be associated with high epilepsy risk, and epilepsy may be associated with high asthma risk among children and individuals in their 30s. Nevertheless, people with epilepsy in other age subgroups should be aware of the possibility of developing asthma within seven years of epilepsy diagnosis.

Breathing training for dysfunctional breathing in asthma: taking a multidimensional approach

Various breathing training programmes may be helpful for adults with asthma. The main therapeutic aim for many of these programmes is the correction of dysfunctional breathing. Dysfunctional breathing can be viewed practically as a multidimensional entity with the three key dimensions being biochemical, biomechanical and psychophysiological. The objectives of this review are to explore how each of these dimensions might impact on asthma sufferers, to review how various breathing therapy protocols target these dimensions and to determine if there is evidence suggesting how breathing therapy protocols might be optimised. Databases and reference lists of articles were searched for peer-reviewed English language studies that discussed asthma or dysfunctional breathing and various breathing therapies. Biochemical, biomechanical and psychophysiological aspects of dysfunctional breathing can all potentially impact on asthma symptoms and breathing control. There is significant variation in breathing training protocols and the extent to which they evaluate and improve function in these three dimensions. The various dimensions of dysfunctional breathing may be of greater or lesser importance in different cases and the effectiveness of breathing training protocols is likely to be improved when all three dimensions are considered. Outcomes for breathing training for dysfunctional breathing in asthma may be most successful when the three key dimensions of dysfunctional breathing are evaluated at the start of treatment and monitored during treatment. This allows breathing training protocols to be adjusted as appropriate to ensure that treatment is sufficiently comprehensive and intensive to produce measurable improvements where necessary.

Breathing exercises for children with asthma

BACKGROUND

Asthma is the most common chronic disease in childhood. Breathing exercise techniques have been widely used by researchers and professionals in the search for complementary therapies for the treatment of asthma.

OBJECTIVES

To assess the effects of breathing exercises in children with asthma.

SEARCH METHODS

We searched for trials in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL and AMED and handsearched respiratory journals and meeting abstracts. We also consulted trial registers and reference lists of included articles.The literature search was run up to September 2015.

SELECTION CRITERIA

We included randomised controlled trials of breathing exercises alone versus control or breathing exercises as part of a more complex intervention versus control in children with asthma.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The primary outcomes were quality of life, asthma symptoms and serious adverse events. The secondary outcomes were reduction in medication usage, number of acute exacerbations, physiological measures (lung function (especially low flow rates) and functional capacity), days off school and adverse events.

MAIN RESULTS

The review included three studies involving 112 participants. All the included studies performed the comparison breathing exercises as part of a more complex intervention versus control. There were no trials comparing breathing exercises alone with control. Asthma severity of participants from the included studies varied. The studies measured: quality of life, asthma symptoms, reduction in medication usage, number of acute exacerbations and lung function. Breathing exercise techniques used by the included studies consisted of lateral costal breathing, diaphragmatic breathing, inspiratory patterns and pursed lips. One study included in the review did not specify the type of breathing exercise used. The control groups received different interventions: one received placebo treatment, one an educational programme and doctor appointments, and one was not described. There were no reported between-group comparisons for any of the primary outcomes. We judged the included studies as having an unclear risk of bias.

AUTHORS' CONCLUSIONS

We could draw no reliable conclusions concerning the use of breathing exercises for children with asthma in clinical practice. The breathing exercises were part of a more comprehensive package of care, and could not be assessed on their own. Moreover, there were methodological differences among the three small included studies and poor reporting of methodological aspects and results in most of the included studies.

Controlling asthma by training of Capnometry-Assisted Hypoventilation (CATCH) vs slow breathing: a randomized controlled trial

BACKGROUND

Hyperventilation has been associated with adverse effects on lung function, symptoms, and well-being in asthma. We examined whether raising end-tidal CO2 levels (ie, Pco2) compared with slow breathing is associated with improvements in asthma control, including peak flow variability.

METHODS

One hundred twenty patients with asthma were randomly assigned to capnometry-assisted respiratory training (CART) for raising Pco2 or slow breathing and awareness training (SLOW) for slowing respiratory rate. Patients received five weekly sessions and completed bid homework exercises over 4 weeks. Blinded assessments at baseline, posttreatment, 1- and 6-month follow-up of asthma control, Pco2, and diurnal peak flow variability were primary outcome measures. Additionally, we measured pulmonary function (spirometry, forced oscillation, exhaled nitric oxide, and methacholine challenge), symptoms, quality of life, and bronchodilator use. Because the control group received active treatment, we expected improvements in asthma control in both groups but more pronounced benefits from CART.

RESULTS

Improvements were seen in 17 of 21 clinical indexes (81.0%) in both interventions, including the primary outcome variables asthma control (d = 0.81), peak flow variability (d = 0.54), quality of life, bronchodilator use, lung function, and airway hyperreactivity. Most improvements were sustained across the 6-month follow-up. Compared with slow breathing, CART showed greater increases in Pco2 (d = 1.45 vs 0.64 for CART vs SLOW, respectively) and greater reductions in respiratory impedance during treatment, less distress during methacholine challenge, and greater reduction in asthma symptoms at follow-up (P < .05).

CONCLUSIONS

Brief interventions aimed at raising Pco2 or slowing respiratory rate provide significant, sustained, and clinically meaningful improvements in asthma control. Raising Pco2 was associated with greater benefits in aspects of lung function and long-term symptoms.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00975273; URL: www.clinicaltrials.gov.

Hyperventilation in asthma: a validation study of the Nijmegen Questionnaire--NQ

INTRODUCTION

The Nijmegen questionnaire (NQ) has previously been used for screening the hyperventilation syndrome (HVS) in asthmatics. However, no validity study has been reported so far.

OBJECTIVE

To examine the validity and reliability of the NQ in asthma patients and identify the prevalence of HVS.

METHODS

The NQ (n = 162) was examined for translation, construct, cross-sectional and discriminant validity as well as for internal consistency and test-retest reliability.

RESULTS

Principal component analysis and exploratory factor analysis revealed a single factor solution with 11 items and 58.6% of explained variability. These 11 NQ items showed high internal consistency (Cronbach's alpha = 0.92) and test-retest reliability (IR = 0.98). Higher NQ scores were found in the following subgroups: women versus men (p < 0.01); participants with moderate versus mild asthma (p < 0.001) or uncontrolled versus controlled asthma (p < 0.001), and participants with breath-hold time (BHT) < 30 versus ≥ 30 s (p < 0.01) or end-tidal CO2 (ETCO2) ≤ 35 versus >35 mmHg (p < 0.001). A cut-off score of >17 discriminated the participants with regard to the presence of HVS. The NQ showed 92.73% sensitivity and 91.59% specificity. The total NQ score was found significantly correlated with ETCO2 (r = -0.68), RR (r = 0.66) and BHT (r = -0.65). The prevalence of HVS was found 34%.

CONCLUSION

The NQ is a valid and reliable questionnaire for screening HVS in patients with stable mild-to-moderate asthma.

Breathing exercises for adults with asthma

BACKGROUND

Breathing exercises have been widely used worldwide as a complementary therapy to the pharmacological treatment of people with asthma.

OBJECTIVES

To evaluate the evidence for the efficacy of breathing exercises in the management of patients with asthma.

SEARCH METHODS

The search for trials led review authors to review the literature available in The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and AMED and to perform handsearching of respiratory journals and meeting abstracts. Trial registers and reference lists of included articles were also consulted.The literature search has been updated to January 2013.

SELECTION CRITERIA

We included randomised controlled trials of breathing exercises in adults with asthma compared with a control group receiving asthma education or, alternatively, with no active control group.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. RevMan software was used for data analysis based on the fixed-effect model. Continuous outcomes were expressed as mean differences (MDs) with confidence intervals (CIs) of 95%. Heterogeneity was assessed by inspecting the forest plots. The Chi(2) test was applied, with a P value of 0.10 indicating statistical significance. The I(2) statistic was implemented, with a value greater than 50% representing a substantial level of heterogeneity.

MAIN RESULTS

A total of 13 studies involving 906 participants are included in the review. The trials were different from one another in terms of type of breathing exercise performed, number of participants enrolled, number and duration of sessions completed, outcomes reported and statistical presentation of data. Asthma severity in participants from the included studies ranged from mild to moderate, and the samples consisted solely of outpatients. The following outcomes were measured: quality of life, asthma symptoms, number of acute exacerbations and lung function. Eleven studies compared breathing exercise with inactive control, and two with asthma education control groups. All eight studies that assessed quality of life reported an improvement in this outcome. An improvement in the number of acute exacerbations was observed by the only study that assessed this outcome. Six of seven included studies showed significant differences favouring breathing exercises for asthma symptoms. Effects on lung function were more variable, with no difference reported in five of the eleven studies that assessed this outcome, while the other six showed a significant difference for this outcome, which favoured breathing exercises. As a result of substantial heterogeneity among the studies, meta-analysis was possible only for asthma symptoms and changes in the Asthma Quality of Life Questionnaire (AQLQ). Each meta-analysis included only two studies and showed a significant difference favouring breathing exercises (MD -3.22, 95% CI -6.31 to -0.13 for asthma symptoms; MD 0.79, 95% CI 0.50 to 1.08 for change in AQLQ). Assessment of risk of bias was impaired by incomplete reporting of methodological aspects of most of the included trials.

AUTHORS' CONCLUSIONS

Even though individual trials reported positive effects of breathing exercises, no reliable conclusions could be drawn concerning the use of breathing exercises for asthma in clinical practice. This was a result of methodological differences among the included studies and poor reporting of methodological aspects in most of the included studies. However, trends for improvement are encouraging, and further studies including full descriptions of treatment methods and outcome measurements are required.

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.

Hypoventilation training for asthma: a case illustration

Hyperventilation-induced hypocapnia is common among asthma patients. This case study illustrates both methodology and results from a patient undergoing training in capnometry-assisted respiratory training (CART). CART is a 4-week training aimed at normalizing basal and acute levels of end-tidal carbon dioxide (PCO(2)) using a portable capnometer. In the presented case, basal levels of PCO(2) increased from hypocapnic to normocapnic range over the course of treatment. Improvements were accompanied by improvements in lung function and reductions in diurnal lung function variability. Improvements remained stable throughout follow-up.

Resting and post bronchial challenge testing carbon dioxide partial pressure in individuals with and without asthma

Objective

There is conflicting evidence about resting carbon dioxide levels in asthmatic individuals. We wanted to determine if transcutaneously measured carbon dioxide levels prior and during bronchial provocation testing differ according to asthma status reflecting dysfunctional breathing.

Methods

We investigated active firefighters and policemen by means of a validated questionnaire on respiratory symptoms, spirometry, bronchial challenge testing with methacholine (MCT) and measurement of transcutaneous blood carbon dioxide partial pressure (PtcCO₂) at rest prior performing spirometry, one minute and five minutes after termination of MCT. A respiratory physician blinded to the PtcCO₂ results assigned a diagnosis of asthma after reviewing the available study data and the files of the workers medical screening program.

Results

The study sample consisted of 128 male and 10 female individuals. Fifteen individuals (11%) had physician-diagnosed asthma. There was no clinically important difference in median PtcCO₂ at rest, one and five minutes after recovery from MCT in asthmatics compared to non-asthmatics (35.6 vs 35.7 mmHg, p = 0.466; 34.7 vs 33.4 mmHg, p = 0.245 and 37.4 vs 36.4 mmHg, p = 0.732). The median drop in PtcCO₂ during MCT and the increase after MCT was lower in asthmatics compared to non-asthmatics (0.1 vs 3.2 mmHg, p = 0.014 and 1.9 vs 2.9 mmHg, p = 0.025).

Conclusions

PtcCO₂ levels at rest prior and during recovery after MCT do not differ in individuals with or without physician diagnosed asthma. The fall and subsequent increase in PtcCO₂ levels are higher in non-asthmatics than in asthmatics and seems to be related with increased number of respiratory maneuvers during MCT.

The effect of physiotherapy-based breathing retraining on asthma control

BACKGROUND

The mechanism of the breathing retraining effect on asthma control is not adequately based on evidence.

OBJECTIVE

The present study was designed to evaluate the effect of physiotherapy-based breathing retraining on asthma control and on asthma physiological indices across time.

STUDY DESIGN

A 6-month controlled study was conducted. Adult patients with stable, mild to moderate asthma (n = 40), under the same specialist's care, were randomized either to be trained as one group receiving 12 individual breathing retraining sessions (n = 20), or to have usual asthma care (n = 20). The main outcome was the Asthma Control Test score, with secondary outcomes the end-tidal carbon dioxide, respiratory rate, spirometry, and the scores of Nijmegen Hyperventilation Questionnaire, Medical Research Council scale, and SF-36v2 quality-of-life questionnaire.

RESULTS

The 2 × 4 ANOVA showed significant interaction between intervention and time in asthma control (F = 9.03, p < .001, η(2) = 0.19), end-tidal carbon dioxide (p < .001), respiratory rate (p < .001), symptoms of hypocapnia (p = .001), FEV1% predicted (p = .022), and breathlessness disability (p = .023). The 2 × 4 MANOVA showed significant interaction between intervention and time, with respect to the two components of the SF-36v2 (p < .001).

CONCLUSION

Breathing retraining resulted in improvement not only in asthma control but in physiological indices across time as well. Further studies are needed to confirm the benefits of this training in order to help patients with stable asthma achieve the control of their disease.

The role of breathing training in asthma management

PURPOSE OF REVIEW

There is considerable public interest in the use of breathing modification techniques in the treatment of asthma. Surveys suggest many people with asthma use them, often without the knowledge of their medical attendants. Extravagant claims have been made about the effectiveness of some techniques, resulting in scepticism from orthodox clinicians. The evidence supporting breathing training for asthma was previously weak, and limited by the small size and methodological limitations of published research.

RECENT FINDINGS

The evidence base for the effectiveness of breathing training has recently improved, with reports from several larger and more methodologically robust controlled trials. These trials are reviewed in this study, and the findings placed in context. Trials have investigated a variety of breathing training programmes delivered by different therapists in different ways. All incorporate some instruction in breathing pattern, usually focusing on slow, regular, nasal, abdominal breathing and reduced ventilation, with patients instructed to practise exercises at home and when symptomatic.

SUMMARY

Current evidence suggests that breathing training programmes can be effective in improving patient-reported outcomes such as symptoms, quality of life and psychological impact; and may reduce the use of rescue bronchodilator medication. There is little evidence that airways physiology, hyper-responsiveness or inflammation is affected by such training. The optimal way of providing breathing training within the context of routine asthma care is still uncertain.

Medically unexplained dyspnea: partly moderated by dysfunctional (thoracic dominant) breathing pattern

BACKGROUND

Dysfunctional breathing (DB) may contribute to disproportionate dyspnea and other medically unexplained symptoms. The extent of dysfunctional breathing is often evaluated using the Nijmegen Questionnaire (NQ) or by the presence of abnormal breathing patterns. The NQ was originally devised to evaluate one form of dysfunctional breathing - hyperventilation syndrome. However, the symptoms identified by the NQ are not primarily due to hypocapnia and may be due to other causes including breathing pattern dysfunction.

OBJECTIVES

The relationships between breathing pattern abnormalities and the various categories of NQ symptoms including respiratory or dyspnea symptoms have not been investigated. This study investigates these relationships.

METHOD

62 patients with medically unexplained complaints, that seemed to be associated with tension and breathing dysfunction, were referred, or self-referred, for breathing and relaxation therapy. Dysfunctional breathing symptoms and breathing patterns were assessed at the beginning and end of treatments using the NQ for assessment of DB symptoms, and the Manual Assessment of Respiratory Motion (MARM) to quantify the extent of thoracic dominant breathing. Subscales for the NQ were created in 4 categories, tension, central neurovascular, peripheral neurovascular and dyspnea. Relationships between the NQ (sum scores and subscales) and the MARM were explored.

RESULTS

Mean NQ scores were elevated and mean MARM values for thoracic breathing were also elevated. There was a small correlation pre-treatment between MARM and NQ (r=0.26, p<0.05), but classification of subjects as normal/abnormal on both measurements agreed in 74% (p < 0.001) of patients. From the sub scores of NQ only the respiratory or 'dyspnea' items correlated with the MARM values. Dyspnea was only elevated for subjects with abnormal MARM. After treatment, both MARM and NQ returned to normal values (p< 0.0001). Changes in NQ were largest for subjects with abnormal MARM pre-treatment. There was a large interaction between the change in the NQ sub score dyspnea and initial MARM values. (p<0.001).

Impact of comorbidities on asthma

Asthma is a common and serious illness with suboptimal outcomes of care. Epidemiological studies show certain comorbidities occurring more frequently than expected with asthma, with some being associated with poor control and a differential response to therapy options. This review summarizes the evidence of clinically important comorbidities, focusing on the best-explored conditions, including rhinitis and rhinosinusitis, anxiety and depression, obesity, gastroesophageal reflux, smoking and dysfunctional breathing. The evidence of epidemiological and pathophysiological associations for these comorbidities is explored, and the practical therapeutic implications are considered. Comorbidities are important for clinicians treating asthma as they may be markers of patients at risk of poor outcomes, they may point to specific effective treatment options and they are important to researchers as possible confounding factors in clinical trials.

Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies

Sustained or spontaneous hyperventilation has been associated with a variety of physical symptoms and has been linked to a number of organic illnesses and mental disorders. Theories of panic disorder hold that hyperventilation either produces feared symptoms of hypocapnia or protects against feared suffocation symptoms of hypercapnia. Although the evidence for both theories is inconclusive, findings from observational, experimental, and therapeutic studies suggest an important role of low carbon dioxide (CO2) levels in this disorder. Similarly, hypocapnia and associated hyperpnia are linked to bronchoconstriction, symptom exacerbation, and lower quality of life in patients with asthma. Raising CO2 levels by means of therapeutic capnometry has proven beneficial effects in both disorders, and the reversing of hyperventilation has emerged as a potent mediator for reductions in panic symptom severity and treatment success.

Acute effects of inspiratory pressure threshold loading upon airway resistance in people with asthma

Large inspiratory pressures may impart stretch to airway smooth muscle and modify the response to deep inspiration (DI) in asthmatics. Respiratory system resistance (Rrs) was assessed in response to 5 inspiratory manoeuvres using the forced oscillation technique: (a) single unloaded DI; (b) single DI at 25 cmH(2)O; (c) single DI at 50% maximum inspiratory mouth pressure [MIP]; (d) 30 DIs at 50% MIP; and (e) 30 DIs at 50% MIP with maintenance of normocapnia. Rrs increased after the unloaded DI and the DI at 25 cmH(2)O but not after a DI at 50% MIP (3.6+/-1.6 hPa Ls(-1) vs. 3.6+/-1.5 hPa Ls(-1); p=0.95), 30 DIs at 50% MIP (3.9+/-1.5 hPa Ls(-1) vs. 4.2+/-2.0 hPa Ls(-1); p=0.16) or 30 DIs at 50% MIP under normocapnic conditions (3.9+/-1.5 hPa Ls(-1) vs. 3.9+/-1.5 hPa Ls(-1); p=0.55). Increases in Rrs in response to DI were attenuated after single and multiple loaded breaths at 50% MIP.

Changes in pCO2, symptoms, and lung function of asthma patients during capnometry-assisted breathing training

In a recent pilot study with asthma patients we demonstrated beneficial outcomes of a breathing training using capnometry biofeedback and paced breathing assistance to increase pCO(2) levels and reduce hyperventilation. Here we explored the time course changes in pCO(2), respiration rate, symptoms and lung function across treatment weeks, in order to determine how long training needs to continue. We analyzed in eight asthma patients whether gains in pCO(2) and reductions in respiration rate achieved in home exercises with paced breathing tapes followed a linear trend across the 4-week treatment period. We also explored the extent to which gains at home were manifest in weekly training sessions in the clinic, in terms of improvement in symptoms and spirometric lung function. The increases in pCO(2) and respiration rate were linear across treatment weeks for home exercises. Similar increases were seen for in-session measurements, together with gradual decreases in symptoms from week to week. Basal lung function remained stable throughout treatment. With our current protocol of paced breathing and capnometry-assisted biofeedback at least 4 weeks are needed to achieve a normalization of pCO(2) levels and reduction in symptoms in asthma patients.

The non-occupational environment and the lung: opportunities for intervention

Many environmental factors, both indoors and outdoors, can cause or worsen respiratory disease. Although in many cases individuals have little influence over environmental exposures (e.g., weather conditions), there are many (such as environmental tobacco smoke (ETS) and outdoor air pollution) where interventions can improve health. While for environmental exposures such as air pollution, remediation largely devolves to the government, for exposures such as ETS advice to individuals in these settings will confer benefit. Climate change has begun to feature more and more in the context of health but how this may affect pulmonary disease remains debatable. It is possible that heat associated changes in allergen exposures may be more than counterbalanced by potential reductions in cold related exacerbations of diseases such as COPD. An improved assessment of environmental exposures is key in how we approach the effects of the environment on lung disease which would allow better understanding of gene-environment interactions and how remediation might influence population health for the better.

Hyperventilation symptoms are linked to a lower perceived health in asthma patients

BACKGROUND

Hyperventilation symptoms are among the sensations asthma patients tend to report during exacerbations of their disease. However, little is known about their importance for the patients' perceived well-being.

METHOD

We therefore studied the association of reported hyperventilation symptoms (Asthma Symptom Checklist) with perceived physical and mental health (36-item Short-form Health Survey) in a sample of primary care asthma patients (N = 190). We also studied the potential role of perceived control of asthma (Perceived Control of Asthma Questionnaire) in mediating any association between these variables.

RESULTS

In hierarchical multiple regression analyses controlling for demographics, asthma severity, and other asthma symptoms (obstruction, congestion, panic-fear, irritation, and fatigue), hyperventilation symptoms were significantly associated with both physical and mental health status. This association was partially mediated by perceived control of asthma.

CONCLUSION

It is possible that hypocapnia creates symptoms that asthma patients cannot control by using their antiasthmatic medication, thus compromising their perceived control over the management of their asthma, and consequently their perceived health. Behavioral interventions should address the problem of hyperventilation in asthma.

Integrated breathing and relaxation training (the Papworth method) for adults with asthma in primary care: a randomised controlled trial

BACKGROUND

An integrated breathing and relaxation technique known as the Papworth method has been implemented by physiotherapists since the 1960s for patients with asthma and dysfunctional breathing, but no controlled trials have been reported. This study evaluated the effectiveness of the Papworth method in a randomised controlled trial.

METHODS

Eighty-five patients (36 men) were individually randomised to the control group (n = 46) or to the intervention group receiving five sessions of treatment by the Papworth method (n = 39). Both groups received usual medical care. Assessments were undertaken at baseline, post-treatment (6 months after baseline) and at 12 months. The primary outcome measure was the St George's Respiratory Symptoms Questionnaire (SGRQ). Secondary outcome measures included the Hospital Anxiety and Depression Scale (HADS), the Nijmegen dysfunctional breathing questionnaire and objective measures of respiratory function.

RESULTS

Post-treatment and 12 month data were available for 78 and 72 patients, respectively. At the post-treatment assessment the mean (SD) score on the SGRQ Symptom subscale was 21.8 (18.1) in the intervention group and 32.8 (20.1) in the control group (p = 0.001 for the difference). At the 12 month follow-up the corresponding figures were 24.9 (17.9) and 33.5 (15.9) (p = 0.007 for the difference). SGRQ Total scores and HADS and Nijmegen scores were similarly significantly lower in the intervention group than in the control group. The groups did not differ significantly following the treatment on objective measures of respiratory function except for relaxed breathing rate.

CONCLUSIONS

The Papworth method appears to ameliorate respiratory symptoms, dysfunctional breathing and adverse mood compared with usual care. Further controlled trials are warranted to confirm this finding, assess the effect in other patient groups and determine whether there is some effect on objective measures of respiratory function.

Targeting pCO(2) in asthma: pilot evaluation of a capnometry-assisted breathing training

OBJECTIVES

This pilot study aimed to evaluate the feasibility and potential benefits of a novel biofeedback breathing training for achieving sustained increases in pCO(2) levels.

METHODS

Twelve asthma patients were randomly assigned to an immediate 4-week treatment group or waiting list control. Patients were instructed to modify their respiration in order to change levels of end-tidal pCO(2) using a hand-held capnometer. Treatment outcome was assessed in frequency and distress of symptoms, asthma control, lung function, and variability of peak expiratory flow (PEF).

RESULTS

We found stable increases in pCO(2) and reductions in respiration rate during treatment and 2-month follow-up. Mean pCO(2) levels rose from a hypocapnic to a normocapnic range at follow-up. Frequency and distress of symptoms was reduced and reported asthma control increased. In addition, mean PEF variability decreased significantly in the treatment group.

CONCLUSIONS

Our pilot intervention provided evidence for the feasibility of pCO(2)-biofeedback training in asthma patients.