Measurement and estimation of human forced expiratory noise parameters using a microphone with a stethoscope head and a lapel microphone.

OBJECTIVE: The time signature of tracheal noise in the 200-2000 Hz frequency band recorded during a forced expiratory manoeuvre (FETa) is a promising tool for diagnosis of bronchial obstructions. FETa is typically registered using a microphone with a stethoscope head placed on the neck over the trachea (stethoscope sensor). We studied basic time and spectral parameters of forced expiratory tracheal noises with a microphone placed near the mouth (lapel microphone, outside the flow of exhaled air) and compared these with measurements via stethoscope sensor, with the aim of providing patient home monitoring via standard personal computer facilities. APPROACH: FETa, 200 Hz band pass times, and frequency responses of signals recorded simultaneously with both sensors were analysed in a sample of 24 healthy volunteers. MAIN RESULTS: Averaged real transfer function of signals from a stethoscope sensor and a lapel microphone in the frequency range 200-1800 Hz was characterized by a slope of -7.2 dB/octave. This is near the slope of -6 dB/octave predicted via theoretical models of both sensors. The lapel microphone and stethoscope sensor were not interchangeable regarding spectral characteristics of forced expiratory tracheal noises. However, FETa measurements in healthy volunteers via stethoscope sensor and lapel microphone showed no significant differences according to U-Mann-Whitney test for independent samples. SIGNIFICANCE: The ability to measure FETa successfully with a lapel microphone placed near the mouth was experimentally demonstrated in healthy volunteers. Additional studies are needed to verify whether FETa measured near the mouth is acceptable for monitoring pulmonary status in patients with asthma or chronic obstructive pulmonary disease.

[Approximate Estimation of Human Bronchial Resistance during Forced Exhalation].

In this article, we present biomechanical, acoustic biomechanical and acoustic anthropometric surrogate measures of bronchial resistance during forced exhalation. It was shown that the biomechanical surrogate measure provides a rather accurate estimate of bronchial resistance in the middle and in the end of the forced expiratory maneuver in healthy subjects. Statistical prediction of the limits of normal bronchial resistance during forced exhalation in healthy individuals was proved to be possible on the basis of acoustic biomechanical and acoustic anthropometric surrogate measurements. We suggest that the ratio of increments of biomechanical and acoustic surrogate measures of bronchial resistance may be useful for estimating the extent of bronchial obstruction and detecting the affected levels of the bronchial tree of patients with obstructive lung diseases.

[Comparision of forced expiratory time, recorded by two spirometers with flow sensors of various types, and acoustic duration of tracheal forced expiratory noises].

In the sample of 44 volunteers forced expiratory time values obtained in spirometers, equipped with flow sensor of Lilly type and turbine flow sensor, and acoustic duration of tracheal forced expiratory noises are compared. It is shown that spirometric forced expiratory time is dependent on flow sensor type. Therefore it can't be used in diagnostic aims.

[Estimation of bronchial tree zones involved in formation of human forced expiratory wheezes through vortex shedding mechanism, depending on the dynamic compression of central airways].

Forced expiratory wheezes (FEWs) are examined for the diagnosis of pulmonary disease. However there is no clarity in the mechanisms and possible localization of their formation. Purpose--Clarification of the formation of FEWs in bronchial levels in different types of dynamic compression. Peak frequency mid-frequency (400-600 Hz) of FEWs of maximum power and peak frequency of high frequency FEWs (600 Hz) of maximum power and speed of the flow at the mouth were measured in the sample of 85 healthy male volunteers (16-23 years). Strouhal coefficients were calculated for variuow levels of bronchial tree according to Weibel's morphometry. It is shown that for FEWs, formed by the vortex shedding with Strouhal coefficients of 0.2-0.3, the trend is shifting their formation zone to the proximal region with increase of dynamic compression of the airways. The most reliable estimates of dynamic compression result in formation of mid-frequency FEWs in the area of exit of intrathoracic portion of trachea into its outer part and in bifurcation of trachea, while the most probable formation zone of early high FEWs are bifurcations of trachea and main bronchi.

[Forced expiratory tracheal noise time in young men under health and bronchial obstruction conditions].

The group of 270 young men (16-25 years) is tested which includs healthy nonsmokers, healthy smokers, bronchial asthma patients with spirometry confirmed obstruction and without it. Forced expiratory tracheal time is registered in the frequency band of 200-2000 Hz. Spirometry indexes and anthropometric parameters are measured. It is shown that forced expiratory time and its ratios to body height, mass and chest circumference reflect airway resistance and these indexes are perspective to reveal bronchial obstruction.

[Dynamics of duration of tracheal forced expiratory noises during long-term isolation in the "Mars-500" experiment].

Dynamics of duration of tracheal forced expiratory noises in a group of volunteers was studied before, during and after 520-days confinement. The duration did not change in most volunteers. Two volunteers demonstrated significant changes of tracheal sounds duration and some spirometric parameters. Increase in duration of tracheal forced expiratory noises and decrease in spirometric parameters reveal ventilatory impairment of obstructive type. Analysis of duration of tracheal forced expiratory noises dynamics during prolonged confinement proves to be a sensitive technique to test ventilatory function changes.

[Gender features of forced expiratory tracheal noises duration in human subjects aged between 17-25 years].

In the sample consisting of 77 men and 53 women aged between 17-25 years it was shown that the duration of tracheal forced expiratory noises is significantly lower in women. However normalizing duration of tracheal forced expiratory noises to height, body mass and chest circumference neglected this difference.

[Characteristics of flow standardized inspiratory lung sounds in healthy].

Objectification of respiratory sounds, recorded on chest surface, is important to assess human broncho-pulmonary system. The aim is to detail the objective characteristics of basic inspiratory sounds. The study involved 36 healthy men aged 19 to 80 years. Under flow rate 0.89 ± 0.18 L/s medians of spectral characteristics of basic inspiratory lung sounds are in the ranges: amplitude level -63.3... -56.5 dB, -3 dB cutoff frequency 269.5-359.4 Hz, -20 dB cutoff frequency 531.3-621.1 Hz, the slope of the spectrum curve between the cut-off frequencies -0.077... -0.050 dB/Hz. The high degree of bilateral symmetry of spectral characteristics is found. Significant upward trend in the cutoff frequencies is revealed between interscapular region and apices or basal areas of the lungs. The 90% limits of intersubject variability of the cutoff frequencies of the spectrum are identified in areas of chest used for lung auscultation.

[Peak frequency of tracheal forced expiratory wheezes during bronhodilatation test].

The response of peak frequencies of the most powerful tracheal forced expiratory wheezes (FEWs) and volumetric flow rates was experimentally evaluated under influence of bronhodilatation test in representative samples of 71 healthy volunteers and 69 patients with reversible bronchial obstruction. Lack of response of FEWs peak frequency in the middle of forced expiratory maneuver was found in patients, while significant reduction of FEWs peak frequency was characteristic for healthy volunteers. The response of peak value of mid-frequency (400-600 Hz) and early high-frequency (>600 Hz) FEWs observed in the middle of forced expiratory maneuver can be interpreted in favor of forced flow mechanism production of these respiratory sounds. The behaviour is consistent with the predictions of the vortex shedding model. Response of peak frequency of late high-frequency (>600 Hz) FEWs indicates the possibility of auto-oscillatory mechanism (independent on flow) involvement in formation of these respiratory sounds.

[Influence of bronchodilatation test on duration of forced expiratory tracheal noises in young men].

A diagnostic effect of evaluation of forced expiratory noises duration in revealing bronchial obstruction was shown previously. The objective is an analysis of response of forced expiratory noises duration to bronchodilatation test with beta2-agonist among homogeneous in age and gender group of healthy volunteers and bronchial asthma patients, which was treated as a model of variable bronchial obstruction, 260 young men (age of 16-25 years) were examined. It was shown that in bronchial asthma patients with spirometry confirmed bronchial obstruction dominated response of shortening forced expiratory noises duration. Furthermore the magnitude of shortening was significantly dependent on background bronchial obstruction severity. Absence of statistically significant response of forced expiratory noises duration dominated among healthy volunteers (nonsmokers as well as smokers) and bronchial asthma patients without spirometry confirmed bronchial obstruction. However shortening response was met significantly frequently in bronchial asthma patients relatively to healthy volunteers. High specificity (86%) of forced expiratory noises duration shortening response to beta2-agonist may be useful for diagnostics.

[Influence of changed gas media on acoustic parameters of human forced exhalation].

In previous study it was shown that duration of tracheal forced expiratory noises is promising to reveal negative changes of lung function after dive. The objective is a study of parameters of tracheal forced expiratory noises in changed gas media. The first experiment involved 25 volunteers (22-60 years), performed forced exhalation under normal pressure with air, oxygen-helium and oxygen-krypton mixtures. The second experiment in the chamber involved 6 volunteers (25-46 years), which performed forced exhalation with air under normal pressure (0.1 MPa), and under elevated pressure 0.263 MPa with air and oxygen-helium mixture. In the first experiment the direct linear dependence on gas density was found for forced expiratory noises common duration in the band of 200-2000 Hz and for its durations in narrow 200-Hz bands, excluding high frequency range 1400-2000 Hz. In the second experiment a significant reversed dependence of high frequency durations and spectral energies in 200-Hz bands (1600-2000 Hz) on adiabatic gas compressibility. Individual dynamics of common duration of tracheal forced expiratory noises under model dive of 16.3 m (0.263 MPa) is more then the diagnostic threshold of this parameter for lung function decrease, previously obtained for divers under normal pressure.

[Acoustical estimation of impact of single dive in closed-type breathing apparatus on human ventilatory lung function].

Diving renders negative influence on human respiratory system especially when oxygen breathing apparatus is used. Spirometry indexes, traditionally used to estimate ventilator lung function, have poor sensitivity to toxic effect of hyperbaric hyperoxia. The objective is to study possibility of revealing minimum impairments of lung ventilator function in oxygen divers by analysis of forced expiratory tracheal noise duration. 48 divers were studied before and after single shallow water dive in oxygen closed-type breathing apparatus. A significant drop of FVC, FEV1 over the group as a whole was found after dive however being in the limits of norm. The significant increase of individual forced expiratory tracheal noise duration, exceeding the natural variability limit (19.6%, p < 0.05), was found in 10 subjects (20.8%). Three of them during dive had respiratory symptoms characteristic for initial manifestations of pulmonary oxygen poisoning. The asymptomatic reversible increase of forced expiratory tracheal noise duration in the rest 7 divers was interpreted as a sign of hidden phase of hyperbaric hyperoxia effect.

[Acoustic and spirometric indices of the external respiration function of divers using closed oxygenous systems].

The influence of asingle diving in equipment of the closed type using respiratory gas mixture with a risen concentration of oxygen on the external respiration function of divers having small experience of underwater works is investigated by means of a tracheal forced expiratory noise analysis. 16 divers and a control group consisting of 13 men (with the age from 19 to 24 years) were inspected. Duration of tracheal forced expiratory noise was measured. Spirographic indices were registered. 10 divers were inspected in dynamics - before diving and immediately after it. T, FVC and FEV1 changes were tested. Significant differences in T and spirographic indices among groups of divers (before diving) and the control one were not detected. On the whole after diving the only significant reduction of indices in the group of divers was connected with FEV1. Significant individual dynamics of spirographic indices was not found. 2 examined divers showed considerable increase in T reflecting bronchial patency aggravation.

[Effect of electronic homeopathic copy of biohumus fertilizer on tomato sprout development]. / Vozdeistvie élektronnoi gomeopaticheskoi kopii udobreniia biogumus na razvitie rassady tomatov.

Electronic homeopathic copies (EHC) are remedies prepared without traditional dilution/potentiation but by means of so-called "imprinting" of initial substance to water (or other carriers) with the help of M. Ray's devices. EHC are interpreted by modern homeopathic medicine as functional analogs of biologically active substances (BAS) in supersmall doses (SSD). The authors have undertaken 3 blind randomised experiments concerning BAS aqueous solution of fertilizer biohumus, its EHC and placebo influence on tomatoes' sprouts development. Filtered and intermixed water have been encapsulated in 1.5-liter polyethylene containers. The solution of fertilizer has been prepared in accordance with the instruction. EHC has been "transferred" from the concentrated fertilizer with the help of Simulator (Metabolics, GB) apparatus. "Deleting" of information have been made for placebo. Seed of tomatoes (kind "Yasniye") have been pre-soaked in preparations and landed in accordingly numbered plastic boxes (97 x 15 x 14 sm) by 40-44 plants in each one. The seedbed was from one well intermixed portion. The plants were top-dressed by preparations (200-300 ml) one time per week. The boxes were exposed in one room (rotation was made twice per week). The plants have been cut up on the 38th day from pre-soaking. The height of a green part and its mass have been measured for each plant. The differences between independent samples (preparations studied) have been estimated. The differences between EHC and placebo have appeared to be reliable, in the first experiment (p < 2 x 10(-4)--mass, p < 10(-9)--height), in the second one (p = 0.014--mass), in the third one (p < 3 x 10(-6)--mass, p = 0.028--height) The results obtained verify a reality of EHC phenomenon. Thus it is quite within reason to suggest an existence of uniform physical (instead of chemical) mechanism of BAS's EHC/SSD structuring and acting on biological objects.

A new approach to acoustical evaluation of human respiratory sounds.

The authors developed a method for more precise detection and analysis of the physical features of respiratory and voice sound transmission to the chest wall. Based on their findings using this method, they designed several devices for acoustic examination and evaluation of components of human respiratory sounds. These devices analyze forced expiratory sounds, distinguish between air-borne and structure-borne sounds, and distinguish abnormalities in voice transmission to the chest wall. Tests of the devices on human subjects confirmed the validity of the authors' theoretical models, which offer promise for the development of a new class of medical diagnostic instruments.

[Device for examining the state of bronchial patency using the acoustic method]. / Pribor dlia issledovaniia sostoianiia bronkhial'noi prokhodimosti akusticheskim metodom.

An acoustic device was proposed to detect bronchial obstruction by analysing a noise process in the laryngotracheal region at the forced expiration. Clinical trials were under way, which revealed persistent diagnosis signs of bronchial patency impairments associated with changes in the duration and shape of the envelope of a recorded acoustic signal, as well as deviations of its spectral characteristic.