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Biomedical subjects

Stefan S Kostianev

Publications and source records attributed to Stefan S Kostianev.

6 recordsLinked to original sources
PubMed2006

Respiratory and cardiovascular functions among smoking and nonsmoking girls from two regions with different air pollution degree.

AIM: The aim of the present study was to analyze the respiratory and cardiovascular functions among smoking and nonsmoking girls attending two schools situated in regions with different levels of air pollution. The characteristic of air pollution is based on the data gathered by stations 1 and 2 belonging to the Uniform National System for Monitoring the Air Pollution in Bulgaria. The participants (n=108, 16.07+/-0.80 years) were separated in two groups: smokers (S1 - from school 1, S2 - from school 2) and nonsmokers (NS1 - from school 1, NS2 - from school 2). All of them performed pulmonary function testing and .cardiopulmonary exercise testing on a treadmill using our modification of the Balke protocol (Marinov et al., 2000). Reference values for European children, previously validated for the Bulgarian population, were used. RESULTS: There are no significant differences in mean levels of VC, IC, FEV1, MEF50 and MEF25 (as a percentage from the predicted value as well). The average level of the Tiffneau index is noticeably higher among nonsmokers from the two regions and is the lowest among smokers from the more polluted area, but a significant difference exists between S2 (88.7+/-5.9) and NS2 (92.6+/-4.7), p=0.047; T(L,CO)%pred: S1 (85.4+/-7.2) vs. S2 (86.7+/-8.2), p=0.048 and NS1 (88.3+/-8.2) vs. NS2 (92.8+/-14.5), p=0.037; V(E)%pred: S1 (127.5+/-9.6) vs. S2 (123.7+/-6.1), p=0.035; higher levels of total lung capacity (TLC%pred), S1 (107.3+/-9.2) vs. NS2 (104.3+/-9.1), p=0.009 and alveolar ventilation (VA), S1 (5.0+/-0.6) vs. NS2 (4.6+/-0.5), p=0.008. CONCLUSIONS: 1. The negative effects of the combined influence of tobacco smoking and air pollution on some respiratory and cardiovascular functions of adolescent girls are more pronounced than each influence alone. 2. The cardiopulmonary exercise test gives adequate information about the combined effect of air pollution and smoking and using it for preventive purposes is an advisable method.

Adolescent↗
PubMed2004

Long-term changes in dyspnea, lung function, and exercise capacity in COPD patients.

OBJECTIVE: To examine longitudinal changes in dyspnea, lung function, and exercise capacity in COPD patients and to compare baseline data of frequent and infrequent exacerbators at trial entry. METHODS: Nineteen stable COPD patients without significant co-morbidity (age, 58.4 +/- 8.4 years; FEV1% = 33 +/- 12%; mean +/- SD) participated in the study. After a mean period of 36 months (range = 24 - 49) the patients were retested using an identical protocol. RESULTS: Repeated measures analysis showed that there was significant deterioration of FEV1 L (from 1.028 +/- 0.349 to 0.928 +/- 0.307; p = 0.007), PImax cm H2O (from 61.9 +/- 24.2 to 42.0 +/- 22.1; p = 0.007), PaO2 mm Hg (from 69.0 +/- 8.6 to 60.1 +/- 6.8; p = 0.003), PaCO2 mm Hg (from 43.1 +/- 4.9 to 47.3 +/- 4.5; p = 0.001), ATS (from 2.4 +/- 1.0 to 2.8 +/- 0.8; p = 0.031), and 6MWD m (from 389 +/- 130 to 341 +/- 135; p = 0.014). There were also changes in IC, T(L,CO)/V(A), PAP and Borg, but they were not statistically significant. Differentiation of patients by frequency of exacerbations per year of observation (> 2 < or =) discriminated them with respect to functional parameters (FEV1, FVC, IC), dyspneic indices (ATS, VAS and Borg) and exercise capacity (6MWD) at the time of enrollment. CONCLUSIONS: 1) Lung function parameters, blood-gas and dyspneic indices, and exercise capacity decline over a mean period of 36 month in patients with COPD; 2) Patients with frequent exacerbations experience more dyspnea and have lower levels of lung function and exercise capacity at trial entry.

Disease Progression↗
PubMed2004

Tidal breathing analysis in school-age children. Comparison with the parameters of forced expiration.

UNLABELLED: Tidal breathing analysis is a method which has the potential to be used for distinguishing and follow-up of airflow obstruction (AFO) in infants, children and critically ill patients. The aim of the present study was to analyse the tidal breathing parameters (TBP) in healthy and in asthmatic school-age children and to compare them with the parameters of forced expiration. SUBJECTS: Two hundred and twenty five healthy children and 100 asthmatics (7 to 14 years- old) took part in the present study. RESULTS: The results show that TBPs exhibit great inter- and intraindividual variability, even if the mean value of 10 consecutive breathing cycles is used. Parameters that reflect the tidal expiratory flow pattern--V(PTEF)/V(E) and T(PTEF)/T(E) demonstrate high variability and no correlation with age, sex and anthropometric parameters in healthy children. These indices are useful for detection of acute changes in bronchomotor tonus in asthmatics - V(PTEF)/V(E) = 36.1 +/- 6.6% vs. 32.6 +/- 6.2% (methacholine) vs. 37.4 +/- 7.5% (salbutamol) and T(PTEF)/T(E) = 34.2 +/- 6.2% vs. 28.6 +/- 7.8% vs. 35.3 +/- 7.5%, resp. (P < 0.05 everywhere; n = 34) as well as for discriminating a group of subjects with AFO vs. controls (V(PTEF)/V(E) = 30.9 +/- 6.5% vs. 35.3 +/- 8.0%; P = 0.005, and T(PTEF)/T(E) = 29.0 +/- 6.7% vs. 32.8 +/- 7.6%; P = 0.016). The evaluation of the area under the ROC curves (AUC) in the asthmatic group showed weak discriminative capacity of T(PTEF)/T(E) and V(PTEF)/V(E) in comparison to FEV1 (AUC of T(PTEF)/T(E) = 0.62; 95%CI 0.51-0.74). CONCLUSIONS: Tidal breathing parameters could add insight t.o the functional profile but are not capable of substituting forced expiration regarding detection of overt airflow obstruction in school-age children.

Adolescent↗
PubMed2003

Cardiovascular and dyspnea response to six-minute and shuttle walk tests in COPD patients.

UNLABELLED: Previous studies focusing on the changes of heart rate, systolic blood pressure and dyspnea caused by the six-minute (6MWT) and shuttle walking distance tests (ISWT) have produced conflicting data. The present study aims at comparing the cardiovascular and dyspnea responses to 6MWT and ISWT in patients with chronic obstructive pulmonary disease (COPD). Twenty patients with clinically stable COPD (age, 56 +/- 9 yrs; BMI, 27.8 +/- 7.7 kg.m(-2); FEV1%pred, 42 +/- 19%; mean +/- Sx) performed three 6MWTs and two ISWTs using standardised protocols. The distances walked in the third 6MWT and second ISWT were 458 +/- 105 and 365 +/- 116 m, respectively. There was a significant correlation between the distances covered in the two tests (r = 0.87; p < 0.001). The 6MWT and ISWT showed similar correlation coefficients with the Baseline Dyspnea Index (r = 0.86; p < 0.001 and r = 0.76; p < 0.001), the Clinical Symptom Scale (r= -0.72; p < 0.001 and r= -0.55; p = 0.011), FEV1 L (r = 0.36; NS and r = 0.30; NS), PImax (r = 0.59; p < 0.008 and r = 0.60; p = 0.001) and the mean pulmonary artery pressure, Doppler echocardiography (r= -0.51; p < 0.029 and r = -0.51; p = 0.032). Although the response to ISWT tended to be greater, we found no statistically significant differences between the two tests in the changes of heart rate (HR), systolic blood pressure (SBP) and dyspnea (Borg) (deltaHR, 17.9 +/- 13.4 vs 23.8 +/- 15.4; deltaSBP, 7.7 +/- 14.6 vs 13.0 +/- 17.0 and deltaBorg, 1.7 +/- 1.1 vs 2.2 +/- 0.9; NS). CONCLUSION: The cardiovascular and dyspnea response caused by ISWT is greater (but statistically not significant) than that generated by 6MWT. The more limited the functional capacity of COPD patients the more similar the response generated by 6MWT and ISWT.

Blood Pressure↗
PubMed2002

Age-related changes of the somatosensory evoked potentials in healthy children.

AIM: The aim of the study was to investigate the configuration and latency of the somatosensory evoked potentials (SEPs) in healthy children for the time from the neonatal period to adolescence. MATERIAL AND METHODS: SEPs were recorded in 67 healthy children--37 boys and 30 girls from 0 to 16 years of age by means of median nerve stimulation. The active electrode was placed above the contralateral parietal cortex on places C3' and C4' and the reference electrode--on Fpz. The filters were 10-1000 Hz and the frequency of the electric stimulus--3 Hz. RESULTS: The depression of the potential in the neonatal period is accounted for by the wide base and low amplitude of SEPs. The configuration of SEPs is identical with that of adult individuals after 3 years of age. The latencies of the waves P15, N20 and P25 decrease progressively with age and lengthen in the period from 9 to 16 years of age, with the increase of height. The interpeak latencies P15 - N20, N20 - P25 and P15 - P25 decrease with age, while the amplitude N20/P25 increase with age. We found significant variability in the amplitude of the potential, most pronounced in the neonatal period. It gradually decreases by 10-14 months of age and after that remains unchanged. We did not find any differences at stimulation between the left and the right hand. CONCLUSION: The age-related changes in SEPs reflect the trends of the development and the maturation of the neural pathways and their better myelinization.

Adolescent↗