Wavelet analysis of voluntary cough sound in patients with respiratory diseases.

Changes in the characteristics of the cough sound may refer to some specific pathological processes and their evolution. In this pilot study we analyzed voluntary cough sound properties in subjects with asthma bronchiale (AB) and chronic obstructive pulmonary disease (COPD) and discriminated them from the control cough sound in healthy subjects. The wavelet transform was used due to a nonstationarity of cough sound recordings. The duration of cough sound was longer during pathological conditions. The longest duration and the highest power of the cough sound were found in COPD. In AB patients, higher frequencies were detected compared with chronic bronchitis and the power of cough sound was shifted to a higher frequency range compared with control coughs. Cough sounds were classified using discriminant analysis with a correct classification rate of about 85-90 %. The method of cough analysis enables an objective quantification of voluntary cough sound with a useful diagnostic and prognostic value.

Analysis of the cough sound frequency in adults and children with bronchial asthma.

It is well known that the frequency distribution of cough sound varies in different pathological conditions. Its identification could have diagnostic value. In this study the cough sound frequency in adults (n=20, 51.7 +/- 11 yrs), children (n=21, 11.8 +/- 0.4 yrs) asthmatics and healthy volunteers (n=25, 21 yrs) was explored. All patients were suffering from bronchial asthma. They were on a stable therapeutic regime and in a quiet status. Voluntary cough sound was recorded by a microphone and a tape recorder an ddigitally processed. Overlapping technique and Fast Fourier Transform were used to estimate the sound spectra. The records were smoothed by the method of Pascal triangle. They demonstrate the mean values of cough sound spectra. The registered pseudo three-dimensional plots of cough sound frequency (1 K spectra as function in time) of adults showed that the intensity of frequencies increased from 100 to 900 Hz in 3-4 waves. These frequencies afterwards decreased and between 1 to 2 kHz a smaller elevation was present. The spectra of children resembled to the spectrum of adults but had a smoother course. The spectra of asthmatics had some specificity and differed from the spectrum of healthy volunteers.

The effect of the pulsatile electromagnetic field in children suffering from bronchial asthma.

From the bibliography it is well known that pulsatile electromagnetic field has an anti-inflammatory and analgesic effect. It causes vasodilatation, myorelaxation, hyper-production of connective tissue and activation of the cell membrane. Therefore our aim was to study the possible therapeutic effect of pulsatile electromagnetic field in asthmatic children. Forty-two children participating in this study were divided in two groups. The 1st group consisting of 21 children (11 females, 10 males, aged 11.8 +/- 0.4 yr) was treated by pulsatile electromagnetic field and pharmacologically. The 2nd group served as control, consisting also of 21 children (11 females, 10 males, aged 11.7 +/- 0.3 yr) and was treated only pharmacologically. Therapeutic effect of the pulsatile electromagnetic field was assessed on the basis of pulmonary tests performed by means of a Spirometer 100 Handi (Germany). The indexes FVC, IVC, ERV, IRV, FEV1, FEV1/FVC%, MEF75,50,25, PEF, PIF and the changes of the flow-volume loop were also registered. The pulsatile electromagnetic field was applied by means of the device MTU 500H, Therapy System (Brno, Czech Republic) for 5 days, two times daily for 30 minutes (magnetic induction: 3 mT, frequency: 4 Hz as recommended by the manufacturer). The results in children of the 1st group showed an improvement of FVC of about 70 ml, IVC of about 110 ml, FEV1 of about 80 ml, MEF75 of about 30 ml, PEF of about 480 ml, PIF of about 550 ml. The increases of ERV, IRV and FEV1/FVC and decreases of MEF25,50 were statistically insignificant. The results in the 2nd group were less clear. The flow-volume loop showed a mild improvement in 14 children. This improvement in the 2nd group was less significant. The clinical status of children and their mood became better. We believe that the pulsatile electro-magnetotherapy in children suffering from asthma is effective. On the basis of our results we can recommend it as a complementary therapy.

The effect of the pulsatile electromagnetic field in patients suffering from chronic obstructive pulmonary disease and bronchial asthma.

Pulsatile electromagnetotherapy (PETh) stimulates biological tissues and processes; it modulates ion exchange across cell membranes and thus regulates the tone of smooth muscles. On the basis of these effects we hypothetized that PETh might treat COPD and bronchial asthma. We examined 117 (61 females, 56 males) adult patients who were decided in 4 groups. The 1st consisted of 16 patients with COPD who were treated by PETh and pharmacologically. The 2nd group (control) consisted of 24 patients with COPD who were treated only with medicaments. The 3rd group consisted of 37 asthmatics, treated by PETh and medicaments. The 4th group (control) consisted of 40 asthmatics treated only with medicaments. The effectiveness of PETh was assessed by lung function tests, which were performed using a Spirometer 100 Handi (Germany). We measured FVCex, FEV1, percentage of FEV1/FVCex, MEF25, 50, 75, PEF and registered the flow-volume loops. PETh was applied by apparatus MTU 500H (Therapy System, Czech Republic). It was administered 10 doses; once daily for 20 min, with a frequency of 4.5 Hz and a magnetic induction 3 T. The initial 3 doses were about 25% lower then the later doses. PETh was very effective in patients with COPD. The measured indexes improved about 200-660 ml or ml x s(-1), except FVC. PETh was less effective in asthmatics. Most indices improved without statistical significance, about 50-620 ml or ml x s(-1). The indices of FEV1/FVC and MEF25 deteriorated. The changes in controls without PETh were very small. (Tab. 2, Fig. 1, Ref. 19.)

The sensitivity of tussiphonography for assessing the effectiveness of treatment.

Our previous studies have demonstrated that tussiphonogram is suitable not only for the detection of pathological condition in the respiratory tract but also for treatment effectiveness assessment. The purpose of this study was to evaluate the possibilities of tussiphonography in detection of already little pathological changes in the airways and lungs. Therefore the changes of voluntary cough sound indexes were compared with pulmonary function tests in selected group of asthmatics before and after a pulsatile electromagnetic therapy in which the effect of therapy on pulmonary function tests was minimal. After magnetotherapy in 18 patients with increased expiratory forced lung capacity by 7.3% and increased peak inspiratory flow by 31.7% in average the voluntary cough sound intensity decreased by 37.8%, the sound duration shortened by 11% and the sound pattern showed the tendency to normalization. The improvement of mentioned cough indexes was absent in 17 patients who were treated by magnetotherapy too, but at the same time suffered from respiratory viral infection and in 22 patients treated only with climatotherapy and antiasthmatics. Changes of flow-volume loops in patients were not in the close relation to other followed indices. The correlation analysis showed a functional connection in relative differences of cough sound indices and some pulmonary function tests. The results confirmed the suitability of tussiphonography to indicate even mild pathological changes in respiratory tract. (Fig. 4, Ref. 21.)

The expiration reflex from the vocal folds.

The authors present their 30 years' experience with expiration reflex. The reflex can be elicited from vocal folds by mechanical, chemical or electrical stimulation of the superior laryngeal nerve of man and laboratory animals, except mice and rats. It manifests itself by a short, forcible expiratory effort without a preceding inspiration which is indispensable for cough effort. The role of expiration reflex is to prevent penetration of foreign bodies into airways, expelling phlegm and detritus from subglottal area. The initial inspiration before expiration is undesired and could lead to inspiration pneumonia. The reflex is well known to laryngologists as '"laryngeal cough." Its receptors are small in number, localised mainly in medial margin of vocal folds deep in mucosa which can explain their stability in pathological conditions of the larygx. Afferentiation of the reflex is via laryngeal nerve similarly to sneezing and cough. Expiration reflex is not co-ordinated by a single "centre" but rather by a network system in the brain stem. Its motor pattern is supposedly produced by "multifunctional" population of medullar neurones in Botzinger complex and the rostral ventral respiratory group involved also in the genesis of breathing and cough. However, in cats also other neurones may play a vital role in production, shaping and mediation of the motor pattern of respiratory reflex, localised in rostral pons, lateral tegmental field or in the raphe medullar midline.

[Personal experience in the use of magnetotherapy in diseases of the musculoskeletal system]. / Vlastné poznatky o pouzití magnetoterapie pri niektorých chorobách pohybového ústrojenstva.

Therapeutic application of pulsatile electromagnetic field in disorders of motility is recently becoming more frequent. Despite this fact information about the effectiveness of this therapy in the literature are rare. The aim of this study was therefore the treatment of 576 patients who suffered from vertebral syndrome, gonarthritis and coxarthritis. For application of pulsatile electromagnetic field MTU 500H Therapy System was used. Pulsatile electromagnetic field had a frequency valve of 4.5 mT in all studied groups and magnetic induction valve 12.5-18.75 mT in the 1st group. In the 2nd group the intensity was 5.8-7.3 mT and in the 3rd group it was 7.6-11.4 mT. The time of inclination/declination in the 1st group was 20/60 ms, in the 2nd group 40/80 ms and in the 3rd group 40/90 ms. The electromagnetic field was applied during 10 days. In the 1st-3rd day during 20 minutes and in the 4th-10th day during 30 minutes. The therapy was repeated in every patient after 3 months with values of intensity higher by 50%. In the time of pulsatile electro-magnetotherapy the patients were without pharmacotherapy or other physiotherapy. The application of pulsatile electromagnetic field is a very effective therapy of vertebral syndrome, gonarthritis and coxarthritis. The results have shown that the therapy was more effective in patients suffering from gonarthrosis, than in patients with vertebral syndrome and least effective in patients with coxarthosis. Owing to regression of oedema and pain relieve the motility of patients improved. (Tab. 3, Ref. 19.)

[Use of recording methods and sound analysis of cough in the study of sound phenomena associated with respiration]. / Pouzitie metódy registrácie a analýzy zvuku kasl'a pre stúdium zvukových fenoménov spojených s dýchaním.

The objective registration of the human body functions is one of the main tasks of the modern and prospective medicine. The registration of the heart, brain, muscles etc. activity have a long tradition. The registration of sound processes, for instance coughing was not solved completely despite their diagnostic importance. The authors worked out a new non invasive and precise method for cough sound registration and analysis which allows evaluation of the sound pattern, intensity and time duration. Application of this method for registration and analysis of the cry of new-borns gave rise to doubts about its suitability for an assessment of other sounds related to respiratory organs, except that of a cough. We registered and analysed the sound samples from Hirschberg's and Szende's (1982) sound archive for the purpose of the evaluation of the acceptability of the described method. The sound phenomena (109 samples of coughing, crying, barking and breathing) we transcribed from a record on a tape. The recorded signal was converted by A/D converter and analysed by computer by means of our own application programme. The sound and its pattern was transformed into a graphical record. This examination was completed by a sound frequency analysis based on the fast Fourier transformation with help of a computer likewise with our own application programme. It was found out that the used method reflected well the quantitative an qualitative differences of the evaluated sound samples. The graphical records reliably expressed the acoustic sound timbre as it shows the records of dog's and seelion's barking, cough, cry and cackling stridor of new-borns. The histographic curves which expressed the sound pattern showed a principally similar course. The intensity of sound examples was different. The sound samples duration were very often longer as the measurable time extent of software (0-819.2 ms) and therefore its evaluation was omitted. The repeated evaluation of the same sound phenomenon gave equal values. The spectrographic analysis confirmed the differences in sound samples. The values of the evaluated cough and cry sounds do not differ principally from the values registered in the previous author's observations. The results proved that the described method of cough sound registration and analysis was suitable for evaluation of different sound phenomena related to respiratory organs. (Fig. 3, Ref. 14.)

Analysis of the cough sound: an overview.

Coughing is presented by a sudden air expulsion from the airways which is characterized by a typical sound. This sound is so characteristic that it allows identification of the cough and its distinction from other vocal manifestations. The cough sound is a very important symptom of well over 100 diseases and other conditions of medical significance. Changes in its character may have a considerable value in identifying the mechanisms of airway pathology present in respiratory diseases. The cough sound gives information about the pathophysiological mechanisms of coughing by indicating the structural nature of the tissue during therapy that leads to certain patterns of cough. Similarly the character of the cough sound gives information about the behaviour of the glottis and whether the glottis behaves differently in different pathological conditions. Analysis of the cough sound record has significant value in prognosis because its changes may indicate the effectiveness of therapy or the progress of disease. Despite recent progress in cough sound research the attention paid to this interesting physiological and clinical problem is still not sufficient to solve completely various open questions, including our correct knowledge of the mechanism of creation of cough sounds.

Influence of simulated mucus on cough sounds in cats.

Although in the clinic the presence of mucus in the airways is known to be an important factor influencing the sound of coughing in pathological conditions, this observation has not been established experimentally. We have substituted mucus in the airways of anaesthetized cats with 0.5 ml of natural undiluted egg albumin (EA) from hens' eggs, or with 1 ml of 10% pig gastric mucin (PGM) in saline. There were obvious changes in the character of cough sounds and significant increases in the intensity of the sounds (+76% with EA, +36% with PGM). The intensity of cough efforts significantly increased but only in the cats with addition of PGM (mean 30%). Removal of EA or PGM caused the opposite effects, a decrease in cough sounds (-41%) and intensity of cough effort (-52%), with simultaneous changes in the character of the cough sounds. There were no clear-cut patterns of cough sounds as has been described for humans. The cough sounds were often present not only during the expiratory phase of cough but also during the inspiratory phase. The results establish an important role of mucus in the airways in the creation of cough sounds.

Effect of experimental lung oedema on cough sound creation.

We have assessed the importance of changes in lung structure on the pattern of cough sound and its creation with 13 anaesthetized cats. Acute lung injury with oedema was induced by i.v. administration of a mixture of fatty acids. Cough was elicited by mechanical stimulation of the mucous membranes of the airways and was evaluated by its intensities of effort and sound before and up to 2 h after administration of the fatty acids. Changes of cough sound pattern were not definitive, there being no typical alterations. The cough effort and sound intensities, induced from the trachea, consistently decreased (by 70-80% in both cases). The cough efforts immediately after induction of oedema were transiently abolished in some cats. The cough values induced from the larynx similarly decreased at 5 min (51-57%) but subsequently gradually returned to control values. There were significant correlations, both for coughs induced from the trachea and from the larynx, and for changes in intensity of efforts compared with sounds. Thus, pathological changes in the lungs modify the intensities both of cough efforts and their associated sounds.

Relationship between the antitussic and analgesic activity of substances.

The authors studied relationship between the antitussic and analgesic activity of substances. The antitussic effect of codeine, tilidine, tramadol and pentazocine has been studied in nonanesthetized healthy cats. The drugs except tilidine, were administered intraperitoneally in a dose of 10 mg/kg body weight. Tilidine was administered intramuscularly in the same dose. Cough induced in nonanesthetized cats by mechanical irritation of laryngopharyngeal and tracheobronchial areas was evaluated by changes of the lateral tracheal pressure. A significant decrease of the subsequent cough parameters was observed after the application of codeine, tilidine, tramadol and pentazocine. Naloxone given 5 min before the application of the drug has not prevented the cough-suppressing effect due to codeine. Naloxone alone administered in a dose of 1 mg/kg body weight has not significantly influenced the experimentally-induced cough reflex in nonanesthetized cats.

[Objective characterization of cough sounds]. / Objektivizácia charakteru zvuku kasl'a.

Objectification of the amplitude of the cough sound is important in determining its physiological or pathological nature. To achieve this aim an assembly for computer analysis in the time and frequency region was tested in an attempt to substitute the special equipment used at present by less expensive and readily available computer technique. At the same time the possibilities were assessed for using some statistical characteristics as diagnostic parameters in determining pathological changes of the cough sound. The physiological sound of cough was found to yield a hyperbola connecting the peaks of the individual bars of the frequency histogram which in pathological cough was represented by a line descending from left to right. Thus the two types of cough can be objectively distinguished.

Spectra of the voluntary first cough sounds.

The voluntary cough sounds recorded according to Korpas and Sadlonova-Korpasova were sampled at a frequency of 20.000Hz and spectra of six consecutive windows of 50ms were estimated. To digitize signals an autotrigger mode was used. The subjects were healthy volunteers as well as patients with chronic bronchitis, asthma, bronchial carcinoma (growing intraluminarly in the 1st or in the 2nd or in the 3rd order bronchi), emphysema, laryngeal nerve paralyzis or laryngotomy. The duration of averaged cough sounds of patients was longer than that of healthy volunteers. The mean power of the spectra in the successive windows showed different patterns in the same group. In the third window of healthy volunteers (0.10 s-0.15 s) a high modulus broad bandwidth (between 1-2 kHz) spectrum was found which was considered as a bronchial "flute", and was probably related to the lowest resistance as well as to the velocity of airflow of cough manoeuvre. This pattern appeared with a delay and/or it was changed in the diseased groups compared to the healthy volunteers. Due to this delay, the spectra of the fifth window (0.20 s-0.25 s) showed somewhat higher harmonics (400-800 Hz) in the patients with chronic obstructive pulmonary diseases (COPD), carcinoma and laryngeal nerve paralyzis than in healthy volunteers. In emphysematous patients in the first (0.00-0.05 s), in the third (0.10-0.15 s) and in the fifth (0.20-0.25 s) windows the fundamental frequency was low (156-176 Hz) compared to that of the other groups. The paralyzed vocal cords functioning as an added resistance to the expiratory effort caused a phase-shift in the cough patterns, similarly to that seen in COPD patients. Due to the cannula, the spectra of patients having laryngotomy had a lot of high harmonics. They also had peaks nearly identical to that of bronchitic patients because they suffered from serious chronic bronchitis. It was found that by examination the cough spectra of series of voluntary cough sound signals it was possible to distinguish healthy volunteers from patients. This examination would therefore be useful for screening of bronchial diseases.

Effects of atropine, acetylsalicylic acid, FPL 55712, and phentolamine on increased histamine responsiveness of cat lung strips under conditions of airway inflammation.

Our recent in vitro studies on airway smooth muscles of cats with turpentine oil inflammation showed an increase of isometric tension of the lung strips to histamine application. This communication describes the effect of atropine, acetylsalicylic acid, FPL 55712, and phentolamine on the histamine contractions of the lung strips derived from control and experimental groups of cats. Pretreatment of the lung strips with atropine and acetylsalicylic acid had no significant effect on histamine induced contraction. FPL 55712 significantly decreased the mean values of isometric contractions after the low doses of histamine in experimental groups of strips. The isometric contractions after higher doses of histamine were not affected by FPL 55712 in both groups of strips. The significant increase of histamine contractions of the lung strips induced by experimental inflammation was reduced by phentolamine. The role of alpha adrenergic receptors in the increased responsiveness of the inflamed lung tissues to histamine is discussed.

Objective assessment of cough suppressants under normal and pathological experimental conditions.

The influences of the antitussive activity of glaucine were studied in 56 non-anaesthetized cats under normal and pathological conditions. Cough was induced by mechanical stimulation of the airways with a nylon fibre. The authors found that if glaucine was administered at a dose of 5.0, 7.5 and 10.0 mg/kg b.w., i.p., it evoked statistically significant suppression on single cough components. After inflammation of the airways was induced with unsoluted croton oil, no decrease in antitussive activity of glaucine could be observed, according to the number of cough efforts, frequency, intensity of maximal cough effort, and intensity of cough attack during expiration. Glaucine used under such conditions was not found to be powerful enough to suppress either the intensity of maximal cough effort or the intensity of cough attack during inspiration. The antitussive effect of glaucine was stronger under pathological conditions (Staphylococcus-induced inflammation). The antitussive effect of glaucine was approximately the same as with codeine if administered in equal doses.