Yu. V. Kistenev

Laser spectroscopy and chemometric study of the specific features of air exhaled by patients with lung cancer and chronic obstructive pulmonary disease

The specificity of exhaled air spectra in the range from 9.2 to 10.6 µm for patients with lung cancer and chronic obstructive pulmonary disease has been analyzed by laser spectroscopy and chemometrics methods. The informativeness of the absorption spectra of exhaled air is compared with that of clinical analysis data.

LaserBreeze gas analyzer for noninvasive diagnostics of air exhaled by patients

A laser gas analyzer has been designed for determining the composition of exhaled air by means of photoacoustic spectroscopy. The analyzer, based on a broadband optical parametric oscillator and photoacoustic detector, provides high-precision rapid analysis of the multicomponent composition of human exhaled air for dynamic estimation of the efficiency of treating bronchus and lung diseases.

Development of Classification Rules for a Screening Diagnostics of Lung Cancer Patients Based on the Spectral Analysis of Metabolic Profiles in the Exhaled Air

The pattern recognition technique was used for the development of classification rules for a screening diagnostics of lung cancer (LC) patients, based on the spectral analysis of metabolic profiles in the exhaled air, measured by the IR laser photoacoustic spectroscopy (LPAS). The study involved LC, chronic obstructive pulmonary disease, pneumonia patients, and healthy volunteers. The analysis of the measured spectra of exhaled air samples was based first on reduction of the dimension of the feature space using principal component analysis (PCA); thereafter the dichotomous classification was carried out using the support vector machine (SVM). The approaches to differential diagnostics based on the set of SVM classifiers usage are presented.

Photoacoustic spectroscopy evaluation of the impact of smoking on the composition of exhaled air in patients with bronchopulmonary diseases

AIM To investigate the impact of smoking on the air exhaled by patients with chronic obstructive pulmonary disease (COPD) and asthmatics, by applying photoacoustic spectroscopy. SUBJECTS AND METHODS The exhaled air absorption spectra (EAAS) were analyzed in healthy volunteers and patients with COPD and asthmatics, by applying an ILPA-1 CO2 laser photoacoustic gas analyzer. The procedure based on the calculation of an integrated estimate (IE) of the state of the object was used to assess the findings. RESULTS Comparison of the IE of EAAS in COPD patients and non-smoking healthy individuals showed that spectra of the compounds, the formation of which was associated with smoking, were recorded in the range of wavelengths corresponding to the 10R branch of CO2 laser generation. This also provided evidence indicating that the exhaled air of asthmatics differed from that of both smoking and non-smoking healthy individuals. The calculations yielded the threshold values of EAAS IE in the range of wavelengths corresponding to the 10P branche of CO2 laser generation, which made it possible to distinguish non-smoking healthy individuals from asthmatics and COPD patients in 94 and 89% of cases, respectively. CONCLUSION The investigation has confirmed that smoking substantially impacts the composition of the air exhaled by healthy individuals. It has been shown that the use of reference groups formed from non-smoking healthy individuals can improve the accuracy of photoacoustic spectroscopy in detecting COPD and asthma. A further development in this direction will open up new prospects for a new method to diagnose COPD and asthma.

Physical Justification of an Increase in the Efficacy of Radiofrequency Systems for Myocardial Ablation

The article presents data on dependence of the myocardial electrical impedance on the temperature. These data have high clinical relevance because radio frequency energy-induced destruction of the myocardium in the course of surgical treatment of cardiac arrhythmias should be performed transmurally. Insufficient transmural myocardial damage results in recurrence of cardiac arrhythmias. Therefore, achieving transmural treatments of the myocardium is of high significance.Studies were performed by using 20 isolated hearts. To evaluate the effectiveness of radio frequency exposure, we studied two temperature settings: myocardial normothermia (36.6 °C) and myocardial hypothermia (20 °C). The depth of destruction as well as the temperatures of the epicardial, endocardial, and intramural myocardium at the points of impact were estimated. Data showed that lower temperature decreases tissue electrical impedance and results in a greater depth of damage.

Kalman filtering in the problem of noise reduction in the absorption spectra of exhaled air

We examined possibilities of the Kalman filter for reducing the noise effects in the analysis of absorption spectra of gas samples, in particular, for samples of the exhaled air. It has been shown that when comparing groups of patients with broncho-pulmonary diseases on the basis of the absorption spectra analysis of exhaled air samples the data preprocessing with the Kalman filtering can improve the classification sensitivity using a support vector kernel with mpl.

Possibilities of laser spectroscopy for monitoring the profile dynamics of the volatile metabolite in exhaled air

In this work we studied applicability of the laser spectroscopy for fixing differences in composition of exhaled air depending on the position of the body in different physical states. Using principal component analysis we show that the use of the laser spectroscopy methods is sufficiently effective to solve this problem and provide additional opportunities for the comprehensive study of the human condition.

Classification of patients with broncho-pulmonary diseases based on analysis of absorption spectra of exhaled air samples with SVM and neural network algorithm application

In this work results of classification of patients with broncho-pulmonary diseases based on analysis of exhaled air samples are presented. These results obtained by application of laser photoacoustic spectroscopy method and intellectual data analysis ones (Principal Component Analysis, Support vector machines, neural networks). Absorption spectra of exhaled air of gathered volunteers were registered; data preparation for classification procedure of absorption spectra of exhaled air of healthy and sick people was made. Also error matrices for neural networks and sensitivity/specificity values in case of classification with SVM method were obtained. This work was partially supposed by the Federal Target Program for Research and Development, Contract No. 14.578.21.0082 (unique identifier of applied scientific research and experimental development RFMEFI57814X0082).

Twin HgGa2S4 optical parametric oscillator at 4.3-10.78 µm for biomedical applications

We demonstrate an optical parametric oscillator (OPO) based on two HgGa2S4 (HGS) crystals with exceedingly wide tuning range from 4.2 μm to 10.73 μm. The HGS OPO was pumped by Q-switched Nd:YLF laser at 1.053 μm with a 5-7 ns pulse duration. Absorption spectrum of ammonia was presented to demonstrate the feasibility of the OPO system for spectroscopic measurements and gas detection.

Wavelet based de-noising of breath air absorption spectra profiles for improved classification by principal component analysis

The comparison results of different mother wavelets used for de-noising of model and experimental data which were presented by profiles of absorption spectra of exhaled air are presented. The impact of wavelets de-noising on classification quality made by principal component analysis are also discussed.