Biomedical Engineering Vo~ 30, No. 1, 1996

BIOLOGICAL FEEDBACK CORRECTION TREATMENT

OF BRONCHIAL

OF RESPIRATION

DURING

ASTHMA

M. I. A n o k h i n , V. N. S e r g e e v , a n d V. L. D o m a n s k i i

UDC 615.471:616.248-053.2-085

~u~on

Bronchial asthma (BA) in children has high incidence (with no tendency to decline), frequent exacerbations, and rather poor prognosis. In recent years the number of children with BA has significantly risen and the general pulmonary disability rate is expected to increase. Therefore, the development of efficacious methods for treatment of BA in children is an urgent problem. Clinical practice of recent years has revealed a rising incidence of allergic reactions. Side effects of drug therapy motivate researchers to search for drug-free treatments of BA, including psychosuggestive therapy, normalization of respiration stereotype, muscular relaxation, etc. Correction of respiration is one such methods which is based on biological feedback (BF) [1-3, 10]. A BF-based method was first used for treating BA by Alexander [4]. Khan [8] reported substantial long-term improvement in a group of 50 pediatric patients with BA treated by the BFbased method. The goat of the treatment was to help children to avoid a BA attack by deliberate relaxation of bronchi in stressful situations. As a results of such treatment, both the frequency of attacks and the use of drugs were reduced. Electromyogram-mediated BF was also used to implement the method of relaxation of frontal and other muscles [6]. This method allowed muscular tension to be reduced significantly. By the end of the 10-month trial o f the BF method, average frequency of BA attacks in the experimental group was only 8.3 versus the background of 31.7 in the control group. Relaxation training was also shown to be more effective than training without relaxation in terms of increase in the maximum (peak) inhalation rate [5]. ;l"hese results support the clinical efficacy of BF-mediated relaxation methods; these are particularly suitable in patients with contraindications to pharmacotherapy. Therefore, new methods of drug-free treatment of BA should be based on the BF principle. tn spite of obvious urgency, no BF-based methods have been yet applied to BA treatment because the choice of devices suitable for BF treatment of BA in pediatric patients is severely limited. One of the first methods of BF respiratory treatment and assessment of its results was proposed by Hillsman [7]. According to this method, air flow parameters of the patient's respiration are monitored by a flow meter and displayed on a monitor screen together with a reference signal of ideal shape. The patient tries to regulate his or her breathing to match the reference signal. A method for respiratory control based on thoracic cavity volume gauges was proposed in [9]. The problem of the development of BF equipment for respiratory control and its introduction into pediatric clinics is still urgent. Equipment The problem was posed to develop a device for visual presentation of a patient's breathing rhythm, depth, and corresponding reference values. This device should be friendly in use and adjustment, should not require special training of personnel, and should be easily adaptable to pediatric practice. A prototype of the device was developed in the preliminary stage of the work. This prototype of the respiratory correction device has the following characteristics. Sechenov Moscow Medical Academy. All-Russian Scientific-Research Institute for Medical Instrument Engineering, Russian Academy of Medical Sciences (VNIIMP-VITA Joint-Stock Company), Moscow. Translated from Meditsinskaya Tekianika, No. 1, pp. 26-29, January-February, 1996. Original article submitted August 10, 1995. 26

0006-3398/96/3001-0026515.00 9

Plenum Publishing Corporation

Two modes of reference signal generation: automatic and manual. The reference rhythm signal is displayed on two parallel vertical scales. Automatic mode allows independent adjustment of reference rhythm signal parameters: inhalation duration, exhalation duration, breathing depth and rate. The ranges of regulation are: inhalation and exhalation duration, from 1 to 3 sec; breathing rate, 10-25 cycles per min; breathing rate, 20-100% of maximum value. Manual mode allows remote control of the referehce rhythm. Spontaneous breathing rhythm is monitored by a thoracic cavity volume gauge. When the device is switched on, a control program stored in ROM is activated. In automatic mode, the reference rhythm signal with set parameters is displayed on the monitor screen. The signal applied from the respiratory control gauge to the input of the control circuit and ROM is amplified, converted into digital form, and applied to a computer in the form of 8bit digital code. Processing time does not exceed 1 msec per sample. Since the breathing rate is substantially lower, real-time processing of the complete breathing cycle is possible. Then the signal is displayed on the monitor in a graphical columnar form. Experimentally measured signal is shown as a column of variable height, which is compared to the reference column of periodically oscillating height. The device allows optional adjustment of the reference signal parameters. The patient with attached gauge is placed in front of the monitor and is asked to synchronize his (her) own breathing rhythm with the reference signal. Methods A total of 91 pediatric patients with BA were examined. All the children received outpatient treatment. The BF method of respiration correction was used in an experimental group (60 children). The control group (31 children) received the usual drug treatment. During the BF-mediated respiration correction the pediatric patients of the experimental group were trained to control the rhythm, rate, and depth of respiration with the aid of the respiratory correction device and to control manually muscular relaxation. The child is placed in front of the monitor placing particular emphasis on the fact that the patient's back should be straight and humeral muscles should be relaxed. Respiratory control gauges were attached to the thoracic cavity. Both physician and patient watched the picture on the monitor screen. The child was taught to synchronize his or her own breathing with the reference signal and to execute abdominal breathing. The training sessions were performed once per day, 15-20 rain each. Then the child was asked to perform self-training 2-3 times per day. At the beginning of the treatment, the children were oriented to natural breathing rate of about 20 cycles per min. Then this rate was gradually reduced to 12 cycles per min. Relaxation of humeral muscles was under particular control. General relaxation, passive expiration, and general sensation of warm body were suggested. Special attention was placed on gradual reduction of respiration depth by the decrease in the breathing amplitude. Average course of BF-mediated therapy took 2 weeks. Then patients took 1 session per week, and after 2 months, only once per month. Results Positive dynamics was observed in the patients of the experimental group. Most children were able to cope with the early symptoms of BA attack or to arrest it without bronchodilators. The attacks were less severe, their frequency reduced, sputum easily expectorated just after the training sessions, and emphysematous inflation of the lung disappeared. X-ray examination of the respiratory tract also supported positive dynamics. Remission duration increased. In children of the experimental group with benign form of BA spirographic examination during a BA attack or in the post-attack period before the treatment course showed symptoms of restrained emphysema and obstruction. After the BFmediated treatment, all the symptoms significantly decreased to normal values inherent in early remission and remained stable within the norm during the catamnesis. The BF-mediated treatment eliminates hypocapnia and increases pCO 2 content to the normal value. There is positive dynamics in the pCO 2 increment per second in the alveolar phase of inspiration, and its duration is significantly reduced. The 27

same e f f e c t s w e r e observed in t h e c o n t r o l group treated with bronchodilators. Changes in r e s p i r a t i o n r a t e w e r e found to be inversely proportional to the pCO 2 content in exhaled air and directly proportional to the pCO 2 increment per second. In other words, irregularity in lung ventilation increases with breathing rate, and infrequent breathing improved the distribution of alveolar gases. Hypoxemia (paO2 < 80 mm Hg) was completely eliminated in two of five children o f the experimental group. Hypocapnia (PaO2 < 30 mm Hg) which was observed in one child in the state of remission was normalized during the treatment. During the treatment BA a t t a c ~ were less frequent, remission duration increased, and doses of routinely prescribed bronchodilators were reduced. Generally, according to clinical observation and functional diagnosis of BA, the results of the drug-free therapy (experimental group) and drug therapy (control group) were similar in children with benign form of BA. Capnography and blood gas assay showed about the same treatment efficacy in pediatric patients with moderate form of BA. Positive dynamics were observed both in clinical symptoms and in functional parameters. BA attacks were significantly less frequent. In 29 patients subjected to BF-mediated treatment, no BA attacks were reported over half a year. Significant improvement was observed in 10 of 25 pediatric patients in the experimental group with infection-allergic BA. In patients with severe form of BA, BF-mediated therapy was used only in combination with traditional drug therapy. The treatment caused positive dynamics, although, in contrast to patients with benign and moderate forms of BA, no correlation was observed between clinical symptoms and functional parameters. Clinical symptoms were significantly better than in the control, but the functional performance of patients of the two groups was virtually equal. The proposed drug-free method of treatment allowed previously used bronchodilators to be completely withdrawn in 70% of the patients of the experimental group and significantly reduced in dosage in the other 30%. Remission duration was I-3 months longer than in the control group. The dysfunction typical for obstruction and emphysema was reported in the catamnesis of the patients of the experimental group receiving non-drug treatment between BA attacks half as often as in the control group. Conclusion

The developed prototype for BF-based respiration correction device allows BF-mediated treatment of BA in pediatric patients to be implemented and basic principles of medical procedure and technical requirements for the procedure and serially produced device to be formulated. The results of clinical trial of the prototype for the BF-mediated treatment device in pediatric patients with BA gave the following conclusions: - the respiratory correction device arrests early symptoms of BA attack without bronchodilators in most pediatric patients with benign and moderate forms of the disease, reduces frequency of BA attacks, prolongs remission, and reduces dosage of prescribed bronchodilators; - reduced obstruction and emphysema (as measured spirographically), normalization of blood gas content, and decreased capnographic symptoms of irregular lung ventilation can be regarded as functional criteria o f positive dynamics of the disease under the BF correction of respiration; - BF correction of respiration in outpatient settings is indicated for patients with benign and moderate forms of atopic BA during acute, post-attack, and inter-attack periods. Such treatment is contraindicated for patients with severe form and during BA attack; - BF respiratory correction reduces psychosomatic disorders, anxiety, dependence on bronchodilators, fear of recurrent attack, tearfulness, erethism, and insomnia. LITERATURE CITED

5.

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