The article discusses the use of methods for assessing lung respiratory function in patients with chronic obstructive pulmonary disease (COPD) and smokers. The aim of the study is a comparative evaluation of the informative value of capnometry, spirometry, multiple breath nitrogen washout method, and diffusion test in patients with COPD, as well as an early detection of respiratory function impairment in smokers. Results. Three groups of patients were examined: 1st — 30 patients with moderately severe COPD, average age 50.6 ± 4.3 years, 2nd — 30 smokers, average age 45.6 ± 2.4 years, 3rd (control group) — 30 practically healthy non-smokers, average age 45.6 ± 2.4 years. Capnometry showed a statistically significant increase in the slope of the alveolar phase in patients with COPD compared to the control group and smokers at rest, both before and after bronchodilator use. Significant differences between smokers and control groups were detected during forced exhalation. According to spirometry data, the FEV1/FVC ratio in patients with COPD was statistically significantly lower compared to the control group and smokers, both before and after bronchodilator use. Diffusion capacity was significantly lower in patients with COPD and smokers compared to the control group. The lung clearance index was significantly higher in the COPD group compared to the other two groups. Conclusions. All the mentioned methods were informative in patients with COPD, but capnometry and lung diffusion capacity assessment were sensitive methods in smokers, revealing uneven distribution of ventilation-perfusion ratios in the lungs and impaired gas exchange function.

Yoga breathing exercises that develop the ability to voluntarily regulate the minute volume of respiration (MV) and maintain the state of hypoventilation, hypoxia and hypercapnia, can be considered as a way of hypoxic-hypercapnic training, potentially capable of influencing cerebral circulation and neuroprotective factors. However, at the moment, individual anthropometric features that affect the ability to develop a hypoventilation mode of breathing have not been studied, and methodological criteria for training have not been developed.Methods: The study involved 44 people (32 men and 12 women) who regularly practice yoga breathing techniques with a voluntary decrease in respiratory rate using maximum tidal volume (TV). Free breathing was recorded for 2 minutes, then each subject performed the respiratory hypoventilation pattern available to him or her (minimum RR values with maximum TV, inhalation and exhalation were of equal duration). The following parameters of external respiration were determined: respiratory rate (RR), minute ventilation (MV), tidal volume (TV), partial pressure of CO2 in the exhaled air at the end of exhalation (PetCO2 ), percentage of O2 in the exhaled air (FeO2) and hemoglobin saturation (SpO2 ).Results: Compared to breathing at rest (MV = M±SD 8.51 ± 2.57 (95% CI 7.72–9.29) l/min; PetCO2 = M±SD 36.98 ± 3.71 (95% CI 35.85–38.11) mm Hg), the mode with RR = 3 times/min (inspiration and expiration for 10 s), n = 44, leads to an increase in MV up to M±SD 12.02 ± 3.42 (95% CI 10.98–13.06) l/min (p < 0.001) and a decrease of CO2 : PetCO2 = M±SD 33.99 ± 3.59 (95% CI 32.90–35.08) mm Hg (p < 0.001) — that is, to development of alveolar hypocapnia. The mode with RR = 1.5 times/min (inhalation and exhalation for 20 s), n = 44, demonstrates a decrease in MV to M±SD 5.95 ± 1.59 (95% CI 5.46–6.43) l/min (p < 0.001) and growth of PetCO2 up to M±SD 41.19 ± 3.71 (95% CI 40.06–42.32) mm Hg (p < 0.001). The mode with RR = 1 time/min (inspiration and exhalation for 30 s), n = 24: with a decrease in RR to 1 time/min, a decrease in MV was observed to M±SD 4.22 ± 0.92 (95% CI 3.83–4.61) l / min (p < 0.001) and an increase in PetCO2 up to M±SD 44.05 ± 3.05 (95% CI 42.76–45.33) mm Hg (p < 0.001). The breathing pattern with RR = 1 r/min is accompanied by a statistically significant decrease in MV compared to rest, as well as an increase in PetCO2 and a decrease in FeO2 , that is, it is hypoventilation. We have proposed a ventilation coefficient (Qvent), which is the ratio MV/VC, which allows us to judge at what values of MV an individual reaches a state of hypoventilation. It was previously shown in this sample that the breathing exercise becomes hypoventilation when Qvent values are equal to or less than 1. With Qvent in the range from 1 to 2, the ventilation mode is within normal values, and when Qvent is more than 2, hyperventilation occurs.Conclusion: when performing yoga breathing exercises, variations in MV are observed both in the direction of hyperventilation and in the direction of hypoventilation with corresponding shifts in gas exchange (hypocapnia with hyperventilation, hypercapnia with hypoventilation). The MV values at which an individual reaches hypoventilation vary from person to person and can be predicted using the ventilation coefficient (Qvent).

The article discusses the possibilities of functional assessment of the state of the respiratory function of the lungs in patients with bronchial asthma.The purpose of the study: a comparative assessment of the information content of capnometry, spirometry, the method of multiple breath nitrogen washout and the diffusion test in patients with asthma.Results and conclusions: 2 groups of patients were examined: I — 30 patients with asthma of 3–4 degrees of severity, II — 30 healthy volunteers. Capnometry showed a statistically significant increase in the slope of the alveolar phase in patients with asthma compared to the control group with quiet breathing, both before and after the use of a bronchodilator. According to spirometry data, in patients, the FEV1 /FVC ratio was statistically significantly lower compared to the control group, both before and after bronchodilator use. In a comparative analysis of the diffusion capacity of the lungs, there was a trend towards lower DLCO values in patients with asthma. A statistically significant difference was obtained in relation to the lung clearance index between the group of patients with asthma and the control group, in which the index was significantly lower. There were no statistically significant differences between the FRC (%) estimates obtained using the diffusion test and the method of the multiple breath nitrogen washout in patients with asthma. Thus, the informative methods in patients with asthma were not only the method of spirometry, but also the method of capnometry and the method of multiple breath nitrogen washout, which revealed uneven ventilation and distribution of ventilation-perfusion ratios in the lungs.

The analysis of the differences in the spirometry estimation using different predicted values systems (Clement R.F., ECSC-1993, Knudson R.J, and GLI2012) have been made. The predicted values for volume indicators (FVC and FEV1) calculated using the GLI-2012 system were higher than those of the first three systems, while the flow indicators (FEF25-75 and MEF75), on the contrary, were lower. This difference has led to a different assessment of deviation of normal when using different predicted values systems. This is especially true when the values are near the evaluated areas borders.

The early signs of bronchial obstruction in smokers - obstruction of the small airways are discussed in the article. It is shown that the more informative spirometric signs of distal obstruction are flow measured at the end of the flow-volume curve and FEF25-75 versus FEV1, FVC and FEV1/ FVC. Diagnostic value of capnometry and nitrogen washout test are shown, which make the possibility to identify changes of the respiratory zone and small airways obstruction with normal spirometric values.

The aim of this study was to evaluate diagnostic value of capnography for early detection of lung function disorders in smokers. Methods. We compared results of capnography and spirometry and selected the most informative capnographic parameters in three groups of patients (n = 25 each): in non-smokers with normal spirometry, in smokers with normal spirometry and both in smokers and non-smokers with airway obstruction. Curves were obtained for continuous measurement of CO2 partial tension (PCO2) against time and volume. Results. A significant increase in the slope of capnographic alveolar phase during both tidal and deep expiration and a tendency to alveolar hyperventilation were found in obstructive patients. Similar, but less prominent results were obtained in smokers with normal spirometry. Conclusion. Capnography could be useful for early detection of lung function disorders in smokers before preceding occurrence of spirometric abnormalities (airway obstruction). PCO2 measurement against time was the most valuable parameter.