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Biomedical subjects

M Vrabec

Publications and source records attributed to M Vrabec.

15 recordsLinked to original sources
PubMed2004

Comparison between degree of carotid stenosis observed at angiography and in histological examination.

BACKGROUND: The generally accepted indications for carotid endarterectomy are the clinical picture and degree of per cent stenosis of the carotid artery. Despite the fact that stenosis measurement is defined, the methods vary considerably. The correlation of particular methods, especially angiography and duplex sonography, has been repeatedly demonstrated. However, the correlation between any technique and true anatomical stenosis, as evaluated on the surgical specimen, has been only anecdotally reported. METHOD: During carotid endarterectomy, the atherosclerotic plaque was removed in one piece and subsequently stored and histologically processed. The histological slides were evaluated under an optical microscope, scanned and the slide with maximum stenosis was determined using a planimetric program. Both the minimal lumen area and the area of the whole plaque were measured. The stenosis was calculated using the planimetric method. On the maximum stenosis slice, the minimal diameter and the diameter of the whole plaque were also measured. Angiographic images were scanned and the per cent stenoses were remeasured, according to the NASCET and ECST criteria. In total, of 147 cases, all above-mentioned parameters were obtained. Student's t tests for paired samples were used to evaluate the results. FINDINGS: The t-tests indicated significant differences between the per cent stenosis as measured on the anatomical specimen and on the angiogram (p<0.05). The results indicate that the angiographic measurement underestimates the degree of in-situ anatomical stenosis. The underestimation was more marked the less the degree of stenosis. CONCLUSIONS: Our study finds that per cent stenosis measurement obtained by angiography with NASCET or ECST methods does not reliably reflect the anatomical degree of per cent stenosis, which makes questionable the rigorous following of percentage stenosis using angiography as the sole indicator for carotid endarterectomy in all cases.

Algorithms↗
PubMed2003

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.

Adult↗
PubMed2002

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.)

Adult↗
PubMed2000

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.)

Adult↗
PubMed1997

[Use of recording methods and sound analysis of cough in the study of sound phenomena associated with respiration].

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.)

Animals↗
PubMed1993

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.

Animals↗
PubMed1993

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.

Animals↗
PubMed1990

[Objective characterization of cough sounds].

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.

Cough↗
PubMedDate not supplied

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.

Cough↗
PubMedDate not supplied

Ocular torsional movements in humans with normal and abnormal ocular motility--Part I: Objective measurements.

Using a corneal marker and cinematography, we analyzed ocular torsional movements during forced head tilt in three patients with superior oblique palsy before and after ipsilateral inferior oblique recession and compared them to those of normal subjects. As the head is tilted in normal subjects, the eye lags behind the head in a slow rolling movement. Periodic rapid wheel-like movements occur in the direction of head tilt which do not completely allow the eye to catch up with the head. This results in a partial compensatory intorsion on ipsilateral head tilt and extorsion on contralateral head tilt. In patients with superior oblique palsy, the rapid extorsional movement on ipsilateral head tilt is greater and faster than in the normal, but becomes slower after inferior oblique recession, indicating it comes from the overacting inferior oblique. The rapid intorsional movement seen during contralateral head tilt is absent in patients with superior oblique palsy, but appears in a diminished form after inferior oblique recession.

Adolescent↗
PubMedDate not supplied

Theoretical effects of surgery on length tension relationships in extraocular muscles.

The main effect of recession or resection of a rectus muscle is thought to be due to an alteration of its length-tension curve (Starling's Law). Because the subsequent straightening of the eye produces a movement of the new insertions of the rectus muscles either anteriorly or posteriorly in the orbit, the actual amount of tightening or shortening of the muscle is not equal to the amount of recession or resection. How much this phenomenon alters the true amount of tightening or shortening of a muscle has important implications in the determination of safe amounts of surgery, which may differ if one is operating on the fixing or non-fixing eye. In addition, the size of the globe should have an important role in determining the response per millimeter of surgery.

Biomechanical Phenomena↗
PubMedDate not supplied

Artifacts of measuring during strabismus surgery.

Several different artifacts can induce errors in measurements obtained during strabismus surgery. Fixating the severed rectus muscle stump with forceps during strabismus surgery can result in a temporary anterior displacement of the insertion. This may result in inaccuracies in determining the site to which the muscle is to be recessed. This displacement was quantified in a prospective masked manner and was found in some patients to result in as much as 1 mm of error. It can be prevented by measuring the recession prior to fixating the insertion stump with forceps; however, it cannot always be prevented by measuring from the limbus, which also introduces other artifacts due to geometric principles. An "advancement effect" occurs during a rectus muscle recession due to the mechanics of suture placement in the muscle. It was quantified in a masked manner and found to be approximately .5 mm in most cases. A "V" shaped deformity of the insertion stump may occur immediately adjacent to the forceps. This deformity frequently distorts the insertion by as much as several millimeters.

Humans↗