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The Role of Biofeedback in Asthma
By Georges Ramalanjaona, MD, DSc, MBA, FACEP
Asthma is a chronic inflammatory disorder of the airways. Airway inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing. These episodes of asthma symptoms usually are associated with widespread but variable airflow obstruction that often is reversible either spontaneously or with treatment.1 More than 17 million people in the United States have asthma, including nearly 5 million children. Each year, asthma results in 2 million emergency department visits with nearly half a million hospitalizations and 5,000 deaths. As a consequence of asthma exacerbations, 3 million days of work are lost and 11 million days of school are missed, three times the rate of other causes of school absenteeism. The estimated annual cost related to asthma exceeds $12 billion.2
Although there is no known cure for asthma, pharmacologic therapies are highly effective in controlling symptoms of asthma. However, these drugs can have debilitating physical and emotional side effects, and patient compliance is estimated to be less than 50%.
Due to such limitations, more progressive treatment strategies combine pharmacologic intervention with psychoeducational programs such as biofeedback to improve health outcomes for adults and children with asthma.3 This article will review the current evidence on the role of biofeedback in the treatment of asthma.
Mechanism of Action
Asthma is characterized by chronic inflammation of the airway and smooth muscle dysfunction. Airflow obstruction is caused by a variety of changes in the airway, including bronchoconstriction, airway edema, chronic mucus plug formation, and airway remodeling. Inflammation causes an associated increase in the existing airway hyperresponsiveness to a variety of stimuli, including allergens, irritants, cold air, and viruses. These stimuli or precipitants result in airflow obstruction and asthma symptoms in the patient with asthma.1 This airflow obstruction is mediated by increased vagal efferent activity that is not effectively countered by sympathetic efferent activity or baroreflex mechanisms.
Biofeedback is defined as a learned method to monitor and gain control over automatic reflex-regulated body functions using data obtained from a monitoring apparatus. Although the various biofeedback techniques are not applied in uniform fashion, they do apply the same underlying principle—the self-regulation of a process typically believed to be involuntary—to achieve clinical benefit.
It is hypothesized that biofeedback affects both respiratory and immune functions in asthma. In one study, biofeedback appeared to lessen bronchoconstriction by inducing relaxation of the facial muscles, which was associated with a decrease in air flow resistance as evidenced by an increase in Peak Expiratory Flow Rate (PEFR) in both asthmatic and healthy children.4 Biofeedback also affects immune function. A biofeedback-assisted relaxation group displayed an increase in blastogenesis (stimulation of undifferentiated cells) in response to mitogens and a decline in number of neutrophils when compared to a control group.5
Although a wide range of biofeedback systems exist, a small number of specific biofeedback techniques have been associated with successful results in treating asthma. They include:
Respiratory Sinus Arrhythmia Biofeedback (RSA-BF). RSA-BF is the pattern of heart rate variation that accompanies the respiratory cycle. RSA-BF amplitude is both vagally mediated and modulated by the sympathetic and autonomic systems, which in turn affect the autonomic changes in asthma. RSA-BF intervenes at these levels to improve asthma symptoms.
With RSA-BF, electrodes are attached to the body to measure heart rate. The electrodes are connected to a device that translates the heart rate into a visual and auditory form. Using these visual and auditory cues and slow deep breathing exercises, patients learn to improve asthma symptoms by controlling heart rate.
Neck/Trapezius Electromyographic Biofeedback (EMG-BF) and Incentive Spirometry Biofeedback. This technique involves training subjects in abdominal breathing and relaxation of thoracic muscles assisted by EMG-BF training of the scalene and trapezius muscles and incentive spirometer training of thoracic muscles during slow and even breathing.
A variety of other biofeedback techniques also may prove useful to asthma patients.
• The electromyogram uses electrodes to measure muscle tension and can be used to promote relaxation in muscles that become tense in response to stress.
• Temperature biofeedback monitors skin temperature as a patient learns to redirect blood flow to specific muscles or organs.
• Galvanic skin response (also used in the lie detector test) measures electrical conductance in the skin, which is related to the activity of the sweat glands and emotional arousal.
• The electroencephalogram, although relatively imprecise, monitors brain wave activity. Patients using this device are trained to activate certain brain wave frequencies to achieve desired mental states.
Although a wealth of literature has been published on the role of biofeedback in asthma, randomized clinical trials (RCTs) are relatively scarce. Limitations of these RCTs include small number of participants, lack of standardized method for biofeedback technique, and relative short-term follow-up.
In one RCT, Harding and Maher investigated 16 adolescent and adult asthmatics who were divided in two groups: The experimental group (n = 8) received two to five training sessions to reach asymptotic levels of voluntary biofeedback cardiac acceleration while a matched control group (n = 8) received only one session.6 Inclusion criteria include history of asthma without other concurrent diseases. Those patients on steroid therapy or showing more than 20% suggestibility index calculated from both bronchoconstriction and bronchodilation trials were excluded. Results showed statistically significant differences (P < 0.01) between PEFR values for the experimental group compared to the control group. Furthermore, the experimental group displayed significant improvement in the post-test versus pre-training period on all three indices of asthma severity (P < 0.05; mean attack frequency per week: 4.12 vs. 6.7; medication usage per week 4.5 vs. 12.8; amount of medication use per attack per week 0.5 vs. 1.6). The control group did not show significant changes in any of the three indices of severity. The authors concluded that biofeedback produced a potential short-term therapeutic benefit on asthma severity and function.
A more recent RCT pilot study by Lehrer et al compared the effect of EMG-BF and incentive spirometer biofeedback with RSA-BF in asthmatic adults.7 The investigators randomly assigned patients to one of three groups: EMG-BF (n = 6), RSA-BF (n = 6), or waiting list control (n = 5). Participants were asthmatic adults, ages 18-65 years (12 females, 5 males) and were screened using the following criteria: a) history of recurrent asthma within the past 12 months and b) abnormal findings on spirometry (FEV1 < 80, FEF50% < 60%). A total of six 30-minute training sessions were given in each respective biofeedback group. Sessions were held weekly for one month and half, and in each of the testing sessions, 5 minutes of airway resistance and ECG were recorded before and after a 20-minute biofeedback session. In the RSA-BF group, there was a progressive and persistent decrease in airway resistance, as well as a significant increase (P < 0.01) in amplitude of Traub-Hering-Mayer (THM) waves (amplitude of cardiac fluctuations associated with breathing at a rate within a frequency of 0.03-0.12 Hz) in heart period compared to other groups. In summary, the authors pointed to a positive effect of RSA-BF in the treatment of asthma. In this study, the effects of EMG-BF were deemed insignificant.
In another RCT, Coen et al investigated the effects of eight sessions of biofeedback-assisted relaxation on asthma severity, pulmonary function, and immunity.8 Twenty patients ages 12-22 years with non-steroid dependent asthma were randomized to a biofeedback relaxation technique applied 15 minutes twice daily (n = 10) or a control group receiving weekly telephone contact (n = 10). Results showed a significant decrease (P < 0.02) in asthma severity and facial muscle tension in the pre- and post-tests of the experimental group, but not in the control group. Improvements in asthma severity were significantly correlated with a decrease in facial muscle tension (P < 0.05, r = 0.72). CD4 and CD8 lymphocyte counts increased by 25% (P < 0.05) in the experimental group compared to the control group. The authors concluded that biofeedback-assisted relaxation training can relieve symptoms of asthma and enhance immune function in young asthmatics.
In a trial notable for duration of follow-up, Kotses et al studied the long-term effects of biofeedback-induced facial relaxation on asthma symptoms in 33 children, ages 7-16 years.4 The children were randomly allocated to either biofeedback training to achieve facial relaxation (n = 15) or biofeedback training to maintain facial tension at a stable level (n = 14). The study design included four phases: four baseline sessions, eight training sessions, four short-term follow-up sessions for up to two months, and four long-term follow-up sessions for up to eight months. The baseline training and short-term follow-up sessions were conducted on a weekly schedule; the long-term sessions were conducted on a monthly basis. Primary outcome measurements included lung function, self-rated asthma severity, medication usage, frequency of attack, and standardized measures of attitude toward asthma. Compared to the control group, the experimental group exhibited significantly better pulmonary function scores (P < 0.05), a more positive attitude regarding asthma, and less anxiety at the two- and five-month follow-ups. However, there were no significant differences on self-rated asthma severity, frequency of asthma attack, or medication usage.
No adverse effects of properly applied biofeedback have been reported. However, biofeedback therapy is not recommended for patients with severe psychosis, depression, or obsessional neurosis, nor for debilitated patients or those with psychopathic personalities. Because biofeedback can change the need for insulin and other medications, patients with endocrine disorders should seek a physician’s advice before adding biofeedback to a treatment plan.
Cost and Commitment
Depending on the condition being treated, biofeedback therapy may represent a significant financial and time commitment. Sessions usually last 30-60 minutes and, to achieve results, 15 or more sessions may be required. Biofeedback may be more effective, especially in the long term, if patients also learn to employ relaxation techniques or self-hypnotism.
Many biofeedback instruments are available commercially; however, the most affordable machines monitor only one system (e.g., a thermometer). Patients should understand that a primary therapeutic goal is to learn the training sufficiently that it may be applied in everyday situations without the help of the machine.
Based on current evidence, biofeedback is a safe and relatively effective therapeutic adjunct for the treatment of asthma in young adolescents and adults.
Biofeedback can be recommended as a complement to conventional pharmacologic intervention for the symptomatic relief of asthma symptoms and as a part of self-regulatory programs to help reduce asthma recurrence. There remains a need to establish standardized protocols for employing the various methods available, and also to further confirm or refute the effectiveness of biofeedback for the treatment of asthma through large clinical trials.
Dr. Ramalanjaona is Associate Chairman for Academic Affairs, Department of Emergency Medicine, Seton Hall University; School of Graduate Medical Education, South Orange, NJ; and Director of Research, Division of Emergency Medicine, St. Michael’s Hospital, Newark, NJ.
1. National Asthma Education and Prevention Program. National Heart, Lung, and Blood Institute, National Institutes of Health. NIH Publication No. 97-4053. Available at: www.nhlbi.nih.gov/health/prof/lung/asthma/practgde/practgde.pdf.
2. Centers for Disease Control and Prevention. Surveillance for Asthma. U.S. 1960-1995. Morbid Mortal Weekly Rev 1998;47:1022-1025.
3. Huntley et al. Relaxation therapies for asthma: A systematic review. Thorax 2002;57:127-131.
4. Kotses H, et al. Long-term effects of biofeedback-induced facial relaxation on measures of asthma severity in children. Biofeedback Self Regul 1991;16:1-21.
5. Kern-Buell CL, et al. Asthma severity, psychological indicators of arousal, and immune function in asthma patients undergoing biofeedback-assisted relaxation. Appl Psychophysiol Biofeedback 2000;25:79-91.
6. Harding AV, Maher KR. Biofeedback training of cardiac acceleration; effects on airway resistance in bronchial asthma. J Psychosom Res 1982;26:447-454.
7. Lehrer P, et al. Respiratory sinus arrhythmia versus neck/trapezius EMG and incentive inspirometry biofeedback for asthma: A pilot study. Appl Psychophysiol Biofeedback 1997;22:95-109.
8. Coen BL, et al. Effects of biofeedback assisted relaxation on asthma severity and immune function. Ped Asthma Allergen Immunol 1996;10:71-78.