Visceral learning in asthma

Behavioral Treatment of Psychophysical Disorders

The behavioral treatment of psychophysiological disorders is reviewed with an emphasis on group outcome research and controlled, comparative group outcome studies. These behavioral treatments tend to fall into three categories: (I) biofeed-back training; (2) relaxation training; and (3) other behavioral techniques including assertiveness training and systematic desensitization.

Guided by two inclusion criteria-seriousness as defined in terms of prevalence and mortality and the existence of a large body of research-this review discusses the following disorders: essential hypertensions, migraine headaches, muscle contraction headaches, asthma, ulcers, and colitis.

Audio-visual biofeedback for respiratory-gated radiotherapy: impact of audio instruction and audio-visual biofeedback on respiratory-gated radiotherapy

PURPOSE

Respiratory gating is a commercially available technology for reducing the deleterious effects of motion during imaging and treatment. The efficacy of gating is dependent on the reproducibility within and between respiratory cycles during imaging and treatment. The aim of this study was to determine whether audio-visual biofeedback can improve respiratory reproducibility by decreasing residual motion and therefore increasing the accuracy of gated radiotherapy.

METHODS AND MATERIALS

A total of 331 respiratory traces were collected from 24 lung cancer patients. The protocol consisted of five breathing training sessions spaced about a week apart. Within each session the patients initially breathed without any instruction (free breathing), with audio instructions and with audio-visual biofeedback. Residual motion was quantified by the standard deviation of the respiratory signal within the gating window.

RESULTS

Audio-visual biofeedback significantly reduced residual motion compared with free breathing and audio instruction. Displacement-based gating has lower residual motion than phase-based gating. Little reduction in residual motion was found for duty cycles less than 30%; for duty cycles above 50% there was a sharp increase in residual motion.

CONCLUSIONS

The efficiency and reproducibility of gating can be improved by: incorporating audio-visual biofeedback, using a 30-50% duty cycle, gating during exhalation, and using displacement-based gating.

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.

Biofeedback-induced voluntary reduction of respiratory resistance in severe bronchial asthma

Attempts to reduce asthmatic symptoms with respiratory resistance (Ros) biofeedback yielded heterogeneous results. The nature of treatment effects remained unclear (e.g. unspecific relaxation, visceral learning); little is known about clinical long-term effects. The present study investigated the suitability of a statistical single-case approach for an adequate evaluation. A female asthmatic underwent 12 Ros biofeedback sessions. Several breathing parameters were recorded during all sessions and pre/post investigations. The clinical course was observed with symptom diaries for 100 days. The subject achieved considerable voluntary control over her Ros, this control was based upon the expiratory flow. In general, the effects on the clinical course were weak; however, asthmatic attacks decreased in the follow-up period. Careful analyses of physiological, psychophysiological, and course variables allowed the identification of the main processes underlying the biofeedback effects. Further studies should investigate the worth of the expiratory flow as feedback variable.

Clinical evaluation of a respiratory resistance biofeedback training

This study evaluated the effectiveness of a respiratory resistance biofeedback training. Fifteen adult asthmatic subjects participated in a feedback training program including twelve feedback sessions (three sessions weekly). Respiratory resistance (Ros) was measured using the forced oscillation method; to prevent subjects from lung hyperinflation, feedback was interrupted when functional residual capacity increased. One-second forced expiratory volume (FEV1), usage of self-administered medication, degree of asthmatic dyspnoea, and general activity were daily recorded in symptom diaries for at least three months, starting four weeks before the first feedback session. Seven subjects showed significant average Ros decreases within the sessions, while mean Ros in two subjects was increased. However, these direct feedback effects were not related to transfer effects outside the laboratory: e.g., not one of the seven successful subjects showed FEV1 improvements, and only in one of them were within-session Ros reductions accompanied by a decreased frequency of self-administered medication during the training period. These results lead to the conclusion that Ros feedback may not be an effective technique for the treatment of bronchial asthma in adults.

A device for functional residual capacity controlled biofeedback of respiratory resistance

A computer-aided procedure is presented providing subjects with analogous visual feedback of respiratory resistance, which is continuously measured using the forced oscillation method. Simultaneous pneumotachographical control of the breathing volume curve makes it possible to prevent reinforcement for decreases of respiratory resistance which are due to increases of functional residual capacity (FRC). Lung hyperinflation is an unsuitable way to reduce respiratory resistance; if it occurs, feedback is interrupted until the subject decreases his FRC to its initial level. Analysis of the data of 15 adult asthmatic subjects which underwent a 12-sessions feedback training showed that no substantial changes of FRC appeared within feedback trials. Advantages of this new biofeedback technique compared to other procedures are discussed with regard to volume control and feedback signal.

Trachea-noise biofeedback in asthma: a comparison of the effect of trachea-noise biofeedback, a bronchodilator, and no treatment on the rate of recovery from exercise- and eucapnic hyperventilation-induced asthma

We review some of the evidence that supports the existence of psychosomatic triggers to bronchospasm in asthmatics, and hypothesize that it may also be possible to consciously reverse bronchospasm using trachea-noise biofeedback. We precipitated significant levels of bronchospasm in 16 asthmatics using exercise or eucapnic-hyperventilation challenges on five occasions, and administered four different treatments and a no-treatment control. The treatments were trachea-noise biofeedback (TNBF), wrong-information TNBF, an inhaled adrenergic bronchodilator, and a placebo inhaler, all given double blind. Half of the subjects had 3 training days in the use of the TNBF device before study. Our results show that TNBF, in the trained subjects only, is associated with a detectable, but not statistically significant, increase in the rate of recovery from bronchospasm over that found with no treatment. We conclude that, although asthmatics seem to have a strong ability to consciously induce bronchospasm, conscious reversal of a full asthma attack using TNBF is limited. Despite contrary conclusions by other investigators, we believe that this study demonstrated little TNBF-assisted recovery from bronchospasm. We suggest that this is because its effect may be inhibited by humoral mechanisms that sustain the attack, but we believe further work is required to support this.

Respiratory resistance feedback in the treatment of bronchial asthma in adults

Two studies evaluated feedback of total respiratory resistance of the airways (TRR) as a treatment for adults with moderate to severe chronic bronchial asthma. Respiratory function tests and questionnaires were used to select the patients and to assess treatment effects. Study I provided eight biofeedback sessions in four weeks (each session containing four, 3-min training trials) plus three pre-treatment and three post-treatment sessions. Over the eight treatment sessions biofeedback failed to produce any significant improvements, although overall the nine patients showed lower mean initial TRR values at the three post-treatment sessions compared with the three pre-treatment sessions. Patients consistently showed improvement following bronchodilator administration at the end of every session. In study II, biofeedback was provided in one intensive session of 20, 2-min trials. While careful instruction about biofeedback was provided to subjects, and more post-treatment measures were included, no significant improvements were shown following biofeedback, but were shown following bronchodilator administration.

Behavioral interventions as adjunctive treatments for chronic asthma

Results of this review of the behavioral literature on asthma therapy indicate that systematic desensitization, operant interventions, and biofeedback treatments have been successful in altering pulmonary functioning, asthma symptomatology, and/or asthma-related behaviors, whereas some evidence for the limited effectiveness of relaxation training has been demonstrated. The clinical usefulness of these techniques remains open to interpretation. It cannot be said, however, that the results reported represent the definitive statement regarding the usefulness of these interventions, due to the lack of methodological sophistication evident in this body of research. Behavioral investigators currently interested in this area have the opportunity to design and implement research strategies which attend to sound methodological considerations and which may present a clearer demonstration of the efficacy of the adjunctive behavioral treatments which have been used with asthma patients for the past several decades.

Biofeedback training of cardiac acceleration; effects on airway resistance in bronchial asthma

Twenty-four volunteers adolescent and adult asthmatics were pre-tested for suggestibility and retained for an investigation of the airway effects of biofeedback induced voluntary cardiac acceleration. Eight subjects were successful in achieving large magnitude voluntary cardiac acceleration after 2-5 training sessions. Eight matched control group subjects received one session of biofeedback assisted training in cardiac constancy. Results revealed that large magnitude heart rate increase was accompanied by a statistically significant increase in Peak Expiratory Flow Rate for experimental group subjects. Control group subjects showed a drop in heart rate and a statistically insignificant drop in PEFR. Clinical records for experimental and control group subjects during the pre- and post-training periods revealed that a significant reduction in the incidence of attacks, the use of p.r.n. medication, and the index of medication use per attack occurred in trained subjects. No change on any of these criteria occurred for control group subjects. The acquisition of the cardiac acceleration response of asthmatic experimental group subjects was compared with the acquisition rate of a matched group of normal subjects receiving one session of biofeedback training. No differences were revealed between the groups in the rate of acquisition. However, symptom-free asthmatics were shown to have PEFR readings significantly below those of the normal group, thus supporting previous findings. The possible implications of these findings for the clinical management of bronchial asthma, are discussed.

Applications of biofeedback to the treatment of asthma: a critical review

Both muscular and respiratory biofeedback procedures have been employed in attempts to reduce symptoms of bronchial asthma. Research relating to these approaches is reviewed in the present article. Biofeedback training both for facial muscle relaxation and for respiratory resistance decrease improves short-term pulmonary function in asthmatic individuals. These forms of training represent promising avenues for the management of asthma. However, unqualified endorsement of these procedures is premature, at the present time, since their influence on asthma-related variables other than pulmonary function has not been determined and since their long-term effects have not been investigated.

Use of biofeedback in weaning paralyzed patients from respirators

Two paralyzed patients who were being treated with mechanical respirators and in whom weaning with intermittent mandatory ventilation failed were treated with regular sessions of biofeedback. Their respiratory volumes were displayed to them on oscilloscopes at bedside. A plastic (Plexiglas) template was placed on the face of the oscilloscope with two horizontal strips of adhesive tape affixed to it; the patient had to achieve a certain tidal volume (TV) to push the tracing outside the space between the horizontal lines. During each session the highest TV achieved determined the target TV to be maintained during the next session. The application of treatment coincided with improved ventilation; both patients were eventually weaned.

Biofeedback and relaxation training in the treatment of psychophysiological disorders: or are the machines really necessary?

The literature on the use of biofeedback and various forms of relaxation training in the treatment of psychophysiological disorders was reviewed; special attention was devoted to studies in which biofeedback and some form of relaxation training were compared. Based on this review, we conclude that there is no consistent advantage for one form of treatment over the other with any psychophysiological disorder for which a comparison has been made, e.g., essential hypertension, migraine headaches, premature ventricular contractions, tension headaches, temporomandibular joint pain, asthma, primary dysmenorrhea, and functional diarrhea. For other disorders in which no comparisons have been made (e.g., Raynaud's disease, sinus tachycardia, peptic uclers, and fecal incontinence) biofeedback seems to be a very promising treatment modality.