RU2173536C2 - Method for diagnosing bronchial patency disorders - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: method involves setting microphone on the patient larynx area inward from the frontal boundary of sternocleidomastoid muscle. When making forced expiration, breathing noise is received by microphone and recorded with portable magnetic tape recorder. When processing the results, the noise process is divided into time intervals and spectral analysis is carried out in the time intervals. Bronchial patency disorders are determined separately in small and big bronchi from narrow bandwidth spectral maximums appearing at given frequencies. EFFECT: high accuracy in determining injured levels of bronchial tree. 2 dwg

Description

 The invention relates to medicine and medical equipment and is intended for non-invasive diagnosis of disorders of bronchial obstruction.

 Flow-volumetric (spirographic) methods for detecting violations of the mechanics of respiration and, in particular, disorders of bronchial obstruction (in the book: Respiratory diseases: Manual for doctors: in 4 volumes. Under the general editorship of N.R. Paleeva, Vol. 1: General Pulmonology / N.I. Alexandrov, A.G. Bobkov, N.A. Bogdanov, et al .; Edited by N.V. Putov - M: Medicine 1989, pp. 302-329. ) The disadvantage of these methods is the low efficiency of detecting violations of obstructive bronchial patency.

 A known method for detecting disorders of bronchial obstruction based on the analysis of breathing noise (P. Lallement., F. Langevin. Contribution to breath sounds analysis and detection of upper airways obstruction. Proc. 3 Mediterr. Electrotechn. Conf. Madrid, oct. 8-10, 1985. Vol. 1, P. 159-162), which consists in recording and analyzing respiratory sounds of quiet breathing over the trachea. The disadvantage of this method is the low efficiency of detecting disorders of bronchial obstruction of the obstructive type due to the use of quiet breathing.

 A known method for the diagnosis of disorders of bronchial obstruction according to the application 5062427/14 (042789) author. Kulakov Yu.V. and others, which consists in measuring the noise of forced expiration and determining violations of bronchial obstruction by exceeding the duration of the noise or the ratio of the duration and amplitude of the threshold values. The disadvantage of this method is the insufficiently high efficiency of detecting disorders, especially in the early stages of the disease and the inability to determine the level of lesions of the bronchial tree.

 The purpose of the invention is to increase the efficiency of determining violations of bronchial obstruction, including the levels of the bronchial tree.

 This goal is achieved by the fact that in the method for diagnosing violations of bronchial obstruction, which consists in recording and analyzing the noise of the forced exit over the trachea, the recorded noise process is divided into time intervals, the spectrum is determined in each interval, the spectra are displayed on the indicator and the spectra are compared at intervals, moreover, violations of bronchial patency are determined by the presence of narrow-band spectral maxima: for small bronchi - at frequencies above the upper cutoff frequency in exhalation tse; for large bronchi - at frequencies below the lower cutoff frequency or above the upper cutoff frequency from the beginning of exhalation, or in the range between the upper and lower cutoff frequencies for a time exceeding the threshold duration.

 A comparison of the proposed method with the known ones shows that it is new, because it consists in determining violations of bronchial obstruction by the time-frequency characteristics of noise during the patient’s forced expiratory maneuver, which has not been previously applied.

 The possibility of increasing the efficiency of diagnosing violations of bronchial obstruction during a forced expiratory maneuver due to such significant distinguishing features as the allocation of narrow-band spectral maxima and comparing their parameters with threshold in frequency and duration does not follow explicitly from the prior art, which indicates compliance the criterion of "Inventive step".

 Using the proposed method will significantly increase the effectiveness of detecting violations of bronchial obstruction and will contribute to the early diagnosis of various pulmonary diseases, which indicates compliance with the criterion of "Usefulness".

 To clarify the essence of the invention in FIG. 1 shows the frequency characteristics of typical acoustic effects recorded during forced expiration (FV), where 1 is the noise of a turbulent jet in the trachea; 2 - noise turbulent stream in the main bronchi; 3 - disruption of the vortices on the bifurcations of the bronchial tree in the range of 2-5 generations; 4 - self-excited excitation of local sections of the mucosa in the upper respiratory tract; 5 - self-oscillatory excitation of local sections of the mucosa in the bronchi of 2-5 generations; 6 - self-oscillations of the closures of edematous tissues in the bronchi further 6-7 generations.

 The proposed method is as follows. The patient, who is sitting on a chair, is placed with a microphone on the right side of the larynx inward from the front edge of the sternocleidomastoid muscle, and is asked to hold it throughout the maneuver. A nose clip is placed on the wings of the nose. Before conducting a forced expiration, the patient is explained in detail the nature and features of the required maneuver, which can be demonstrated. In this case, special attention is paid to the completeness of inspiration and the most rapid development of the maximum exhalation effort and its maintenance throughout the entire maneuver (requirement and procedure similar to those used in spirography). During forced expiration of the patient, respiratory sounds are perceived by the microphone and can be recorded on a portable tape recorder. When processing the results, the noise process is broken down in time into intervals and spectral analysis in time intervals, the results of which are most conveniently displayed in the form of a relief spectrum (Fig. 1). In this case, on the appearance of the above spectral and temporal features, conclusions are drawn about the presence of violations of bronchial patency. Studies of more than 500 patients and healthy individuals show that for adult patients, the value of the lower cutoff frequency is 100 Hz, the value of the upper cutoff frequency is 700 Hz, and the threshold duration is 400 ms.

 At the same time, the numerical values of the thresholds in frequency and duration given as an example do not reflect subtle variations in deviations from the norm by age, sex, etc. groups of patients, which will be specified further in the process of medical use.

 To prove that the above signs of a change in the spectrum of the noise process during forced expiration indicate a deviation from the norm, we consider the features of noise generation during forced expiration.

 The fact that the occurrence of respiratory sounds is associated with turbulence of air currents is well known, however, very little effort has been made to quantitatively describe the mechanisms of noise formation in a bronchial tree. In relation to forced expiratory noise (FV), an approach related to the application of the model of acoustic noise of ventilation systems was proposed by the authors in the article (Korenbaum V.I., Tagiltsev A.A., Kulakov Yu.B. Acoustic effects in the human respiratory system during forced expiration . // Acoustic Journal 1996., v. 42 - in print.). Based on a numerical estimate of the linear air flow rates in different parts of the bronchial tree from the measured values of the instantaneous volumetric velocity and the study of the characteristic spectral features of noise in various phases of the PV, the authors were able to identify the hypothesized mechanisms of noise formation and to establish their belonging to certain levels of bronchial tree generation. Of course, the proposed physical model of noise generation in the PV process is idealized to one degree or another. However, the proposed approach in combination with the accumulated experience of experimental studies (more than 500 people) made it possible to determine the frequency regions characteristic of the main acoustic effects of forced expiration (Fig. 1.).

 So, the noise recorded in the PV, are divided by the nature of their origin into aerodynamic and self-oscillating. In healthy individuals, with an increase in the rate of exhaled air flow, a relatively broadband noise of a turbulent boundary layer is first observed, having a spectrum on the trachea close to white noise in the frequency band of about 50 - 450 Hz.

 An increase in the flow velocity leads to a sequential turbulization of the flow, starting from the trachea, and the appearance of turbulent jets that are much more powerful than the previous ones — 1.2 (Fig. 1), characterized by broadband spectral maxima in the frequency regions of about 200 Hz (trachea) and 300 -400 Hz (main bronchi).

 In the process of development of expiratory stenosis (Physiology of respiration. / Ed. By I.S. Breslav, G.G. Isaev - St. Petersburg: Nauka, 1994. S. 7-120.) In individual sections of the bronchial tree, starting from the lobar bronchi, such significant linear flow velocities are achieved (more precisely, the ratio of linear velocity to the diameter of the bronchus) that it becomes possible to stall vortices on turbulators, the role of which is played by bifurcations of the bronchial tree (stepwise increase in cross section). The latter effect is characterized by the appearance of a powerful narrow-band spectral maximum - 3 (Fig. 1) in the frequency range 400 - 600 Hz (heard by a whistle) and can shift upward in frequency over time, which reflects the shift of the zone of maximum resistance to expiration from fractional to segmental and subsegmental bronchi in the process of developing expiratory stenosis accompanying PV. According to the observations of the authors, this effect is observed in most healthy individuals of young and mature age when performing the PV maneuver with maximum intensity. In patients with impaired bronchial obstruction, an increase in the duration of this phase of PV is observed over 400 ms, which is associated with an abnormal increase in airway resistance in the region of 2-5 generations of the bronchial tree.

 Due to a drop in the air flow velocity, all other narrow-band spectral maxima - wheezing and whistles of different keys - 4, 5, 6 (Fig. 1), unlike the purely aerodynamic processes discussed above, are self-oscillations associated with modulation by a mechanical oscillatory system (resonator) air flow. The numerical estimates made by the authors show that whistles of 5.6 with frequencies of more than 300 - 400 Hz can be explained by the excitation of fluctuations in the closure of mucosal tissues, which is consistent with the assumption of P. Forgacs (P. The functional basis of pulmonary sounds. // Chest. 1978. V. 73. P. 399 - 405). At the same time, lower frequency rales 6 (Fig. 1) are most likely associated not with the closure of the walls of the bronchi, but with the bending vibrations of the edematous indentations (tongues) of the tissue or clots of secretion. Since all self-oscillating mechanisms of sound formation are associated with physiological abnormalities, the appearance of any of the signals 4-6 (Fig. 1) or their combination, as shown by examinations of more than 500 people, is a stable diagnostic sign indicating violations of bronchial patency at appropriate levels bronchial tree.

 As an example, the results of a survey of a man, 29 years old, have a history of frequent acute infectious bronchitis. Smoking experience more than 10 years. According to the indications of computer spirography, the ventilatory function of the lungs is not impaired. Radiological changes in the pulmonary pattern are absent.

 Using the proposed method, a relief spectrogram was obtained (Fig. 2), the analysis of which implies the presence of narrow-band spectral maxima at the end of the PV at frequencies of about 1000 and 1600 Hz, which indicates a violation of bronchial patency in the region of small bronchi (hereinafter 6-7 generations of the bronchial tree ) The presence of narrow-band spectral components with frequencies below 100 Hz indicates obstructive phenomena in the upper respiratory tract, which is most likely associated with smoking. The duration of the vortex disruption process is a narrow-band spectral maximum with a frequency of about 500 Hz, the only one lying between the upper and lower threshold frequencies (Fig. 2) does not exceed 0.25 s, which is normal and indicates the absence of obstructive phenomena in the range of 2-5 generations of the bronchial tree. Thus, on the basis of the proposed diagnostic method, a conclusion can be made on the presence of signs of bronchial obstruction in a patient with localization in the region of small bronchi.

 To implement the proposed method, specialized equipment has been developed, manufactured and investigated under clinical conditions. This equipment is a hardware-software complex containing: an acoustic sensor based on the MKE-3 microphone, a cassette recorder (recorder), an interface board of the L-152 types (L-153, L-154) installed in the computer system unit, and actually computer type IBM PC / AT. Specialized software (application package "TFGTEST") contains driver programs for controlling the board, as well as the main software package that works in interactive mode and performs data input and spectral analysis with a graphical representation in the form of a relief spectrum (Fig. 2).

 The proposed method allows not only to greatly simplify the conduct of screening examinations in an outpatient setting, but also to increase the effectiveness of detecting disorders of bronchial obstruction of the obstructive type, including the determination of predominantly affected levels of the bronchial tree.

 The advantage of the proposed diagnostic method is the possibility of safe and easily feasible monitoring of the dynamics of the patient’s condition over time, including with the aim of checking the effectiveness of the prescribed drugs. An advantage is also the exclusion of the danger of mutual infection of patients during the examination, which is encountered when using flow-volume methods.

Claims (1)

 A method for diagnosing disorders of bronchial obstruction, which consists in recording and analyzing respiratory noise, in which the noise process is divided into time intervals, spectra are determined, displayed on an indicator and spectra are compared at intervals, characterized in that the noise of the forced exit over the trachea is recorded, and bronchial disturbances patency in the area of small bronchi is determined by the presence of narrow-band spectral maxima at frequencies above the upper cutoff frequency at the end of the exit; impaired bronchial obstruction in the region of large bronchi is determined by the presence of narrow-band spectral maxima at frequencies above the upper cutoff frequency at the beginning of the exit or at frequencies below the lower cutoff frequency, as well as by exceeding the threshold duration of the process of vortex disruption by a narrow-band spectral maximum lying in the range between the lower and upper boundary frequencies.

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