[Effects of additional breathing resistance on oxygen consumption in healthy subjects].

Decrease of oxygen delivery is common in hypoxia. This is the reason of decrease of consumption (VO2) at Mammalia including human. Previously, we have described a hypoxic hypometabolism at 1/3 health persons breathing 17% O2 oxygen air. This light hypoxic (latent hypoxic) condition didn't issue hypoxia because of SpO2 had dropped from 97-98% to 95-96%. We hypothesized the existence of another reason for VO2 decrease. This is the ability of tissue to decrease oxygen consumption in human organism. Thus the hypometabolism maintains delivery/consumption O2 balance when respiratory center is informed by afferent receptors about potential threat of tissue hypoxia. The aim of this study was to investigate parameters of gas exchange in light mixed resistive load 0.4 cmH2O s L(-1). For compare it was used date obtained at ordinary mouthpiece with resistance less 0.1 cmH2O s L(-1). During the study 14 health subjects (6 men and 8 women) with the age ranging from 23 to 48 years were observed. Date showed a significant decrease in mean (SD) of VO2 at 9% and CO2 release (VCO2) at 10%. Value of SpO2 didn't change and remain 97.5%. The results suggest that hypometabolism may be a reaction prevented by disturbance O2 delivery/consumption for tissue of human organism.

[The capnography parameters in healthy adults and patients with psychogenic dyspnea].

A comparison is made the end-tidal fractional concentration of carbon dioxide (FetCO2) and breathing frequency (f) obtained by capnography between 106 healthy persons (H-group) and 30 persons with a psychogenic dyspnea (P-group). The structure of a respiratory cycle was estimated by parameter R(CO2). It was calculated by relation of time of an exhalation to time of all respiratory cycle. Degree of "breath arrhythmia" was estimated by means of parameter CVR(CO2). It was the coefficient of variation (CV) for R(CO2) recorded during the 5-min capnography. The groups was differed for all parameters (p < 0.01), except for R(CO)2 (structures of a respiratory cycle). FetCO2 at H-group was 5.24 +/- 0.36%, at P-group 4.07 +/- 0.47. The breathing frequency at H-group was 14.3 +/- 3.7 br/min, at P-group 17.9 +/- 4.5 and CVR(CO2) at H-group was 8.9 +/- 2.7%, at P-group 12.7 +/- 3.1. We conclude that the most informative indicator of a psychogenic dyspnea is the complex of parameters taking into account all three characteristics of a pattern of breath: decrease FetCO2, increase f, and rhythm of breath.

[The variability of respiratory pattern and gas exchange].

It is known, that spectral analysis of heart rate and respiratory variability allows to find out the very low frequency (VLF) rhythm. However it is not known, it is necessary to carry this rhythm to what type of wave processes. The purpose of the present researches was to study the respiratory variability and the variability of gas exchange parameters. 10 healthy subjects have been surveyed. The pneumogramms within 30 minutes spent record, and then a method "breath-by-breath" within 30 minutes registered gas exchange parameters (Ve--lung ventilation, V(O2) -O2 consumption and other parameters). Fast Fourier transform method has found out two groups of the basic peaks. The first--in a range 0.2-0.3 Hz (a time cycle--3-5 s), that corresponds respiratory frequency which size at subjects varied from 12 to 20 per minute. The second--in a range 0.002-0.0075 Hz, that corresponds VLF diapason (a time cycle--1-3.5 minutes). At the analysis pneumogramms rhythms in the same ranges have been established. The carried out researches allow to draw a conclusion on steady character of wave process in a VLF-range. It can be carried to quasi-periodic oscillations type. First oscillator or respiratory frequency it is formed by means of mechanisms of chemoreception. Considering, that V(O2) and V(CO2) are function energy exchange, it is possible to believe, what exactly energy demand define the second oscillator.

[The increase of carbon dyoxidi production at hypoxia in health subjects].

Pulmonary gas exchange, SpO2 and heart rate at 15-min hypoxia (respiration by air with 0.17; 0.15 and 0.13 oxygen fractions) have been investigated in 24 health subjects. It has been established, results of the group analysis and the results of the individual analysis had been differed. Reaction on hypoxia at the group analysis had been found only at 0.13 02 fraction. It was only hyperventilation. The individual analysis had revealed 4 types of reaction on hypoxia already at 0.17 and 0.15 02 fractions: (1) hyperventilation, (2) decrease of oxygen consumption, (3) increase of ventilation effectiveness, (4) increase of CO2 production. The mechanisms of last reaction are unknown, but we supposed it was connected with anaerobic metabolism. The reactions were detected at light hypoxia (0.17 and 0.15 oxygen fractions) in 90% health subjects when SpO2 decreased to 87-93%. The increase ventilation has been detected at hypoxia within respiration 0.13 oxygen in 60% subjects when SpO2 decreased to 83-87%, while other reactions were nearly absent.

[Oksiv-Del'ta preproduction system for functional diagnosis of the gas-exchange function of lungs].

The results of testing of a preproduction version of the Oksiv-Del'ta spirometabolic system for examination of the metabolic rate and the gas exchange rate in lungs are presented. Testing in volunteers was performed both in a normoxic environment and using air mixtures with various O2 concentrations. The results of testing were used in debugging the Oksiv-Del'ta spirometabolic system and its preparation to clinical trial.