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Biomedical subjects

M A Pogodin

Publications and source records attributed to M A Pogodin.

At least 19 recordsLinked to original sources
PubMed2003

[Self-controlled artificial respiration].

We compared respiratory parameters during natural and self-controlled mechanical breathing to investigate mechanisms of respiratory control in alert humans. The self-control of mechanical breathing is realised manually: duration and velocity of air flow are controlled by left and right hands, resp. In this case, the respiratory afferent information is used to control activity of hand muscles but not of breathing muscles. The findings show that lung ventilation during self-controlled mechanical breathing increases by 7.5 l/min. at resting, by 6.3 l/min. during an exercise, as compared with the natural breathing. The increase in the lung ventilation occurs on account of an increase in the tidal volume but the frequency of the self-controlled mechanical breathing tends to be lesser at resting and was statistically significantly lower in exercise that at natural breathing. The exercise increases the lung ventilation by 13.0 l/min. at natural breathing and by 11.8 l/min. during self-controlled mechanical breathing. The findings suggest that the increased lung ventilation during self-controlled mechanical breathing is connected with creation of a new movement skill, and the modified pattern of self-controlled mechanical breathing is caused by a process of cortical transformation of respiratory afferents signals to efferent signals towards the hand muscles.

Adolescent↗
PubMed2000

[Effect of the body antiorthostatic posture on various circulation and respiration parameters in anesthetised cats].

In anaesthetised cats, antiorthostatic posture of the body with an inclination angle of 30 degrees increased pressure in the vena cava superior and in jugular vein. The rest of the cardio-respiratory parameters were changed insignificantly. Physical and physiological mechanisms of the blood regional redistribution in alteration of the body gravitation orientation, are discussed.

Anesthesia↗
PubMed2000

[Influence of breathing at negative pressure on redistribution of local blood volumes in anti-orthostatic load in cats].

To improve methods of offsetting the hemodynamic shifts in microgravity, applicability of breathing at negative pressure (BNP, pressure relief by -5.0 cm of water column) during inspiration and expiration was assessed in acute experiments with unconscious cats tilted head-down (-30 degrees). Direct measurement of pressure in v. cava superior and v. jugularis externa using a catheter revealed a concurrent significant (p < 0.05) growth of the parameter which should be considered a sign of impeded venous outflow from the craniocervical vessels. BNP added to the sucking effect of the thoracic cavity (the siphoning effect) and led to more massive venous outflow from cephalic vessels as evidenced by pressure drop in the jugular vein and v. cava superior to the values determined in the basic horizontal position. However, BNP did not significantly alter arterial hemodynamics, respiration pattern or gas exchange. Data of the investigation attest effectiveness of this method of moderating blood flow to the cat's head during HDT and possibility to apply it in the zero-g environment.

Animals↗
PubMed1994

[The capacity of humans to regulate the artificial ventilation of their own lungs].

The subjects were given the possibility to control the capacity of the artificial ventilation apparatus (AVA) at resting and during physical work. The subjects were able to find such a level of the artificial ventilation when he or she could delay natural respiratory movements. The subjects seem to orient themselves to afferents from the chemoreceptors in this task. The subjects could not delay the respiration during physical work, obvious hypocapnia being preserved at that.

Adult↗
PubMed1992

[Maximal pulmonary ventilation and the forced expiratory rate under hyperbarism].

In divers, breathing with artificial gas mixtures of 14.3 g/l density, the maximal lung ventilation and the maximal velocity of forced expiration decrease along with an increase in the mixture density. The decrease of these parameters is unrelated to nitrogen anesthesia or exhaustion of respiratory muscles. The findings suggest that the value of both these parameters is only limited by expiratory dynamic compression of respiratory pathways.

Atmosphere Exposure Chambers↗
PubMed1983

[Duration of inhalation and exhalation in increasing hypercapnia and the effect of additional resistive inspiratory resistance].

In healthy subjects, patterns of inhalation and exhalation durations during growing hypercapnia were studied in free breathing and under the effect of resistive inspiratory resistance 20 and 35 cm H2O/1/sec. Pattern of the inhalation duration was divided into two ranges: the inhalation elongated in the first range and shortened in the second one. The border between these ranges corresponded in free breathing to CO2 tension of exhalation terminal portion (PETCO2)--47.2 +/- 1.0 mm Hg (M +/- m). The 1st range was found in 2/3 of cases in the exhalation duration pattern. Under the effect of additional inspiratory resistance, the border between the two ranges of inhalation pattern shifted towards greater PETCO2 values and was 51.0 +/- 1.0 mm Hg for the greater resistance. The 1st range was found in 1/3 of cases in the exhalation duration dynamics. The shift of the border between the ranges of the inhalation duration pattern occurring in breathing with a resistive load in the course of growing hypercapnia seems to result from an augmentation of cortical effects upon breathing and/or weakening of afferent influences from the lung stretch receptors under these conditions.

Adolescent↗
PubMed1980

[Respiratory responses to CO2 by controlled alveolar hypercapnia].

A method is suggested for evaluating the respiratory response to the hypercapnic stimulus by means of increasing the alveolar pCO2 in accordance with the program assigned. The results obtained are not related to the metabolic level, respiratory resistance or other factors. In contra-distinction to the widely applied method of recurrent respiration, the method suggested allows a comparison of CO2 ventilatory sensitivity at rest, during muscular exercise, at altered respiratory resistance, etc. It can be used both clinically and experimentally.

Animals↗
PubMed1978

[Criteria for quantitative assessment of respiratory system reactions].

In anesthetized cats and in healthy humans, lung ventilation, activity of diaphragmal motoneurons and intercostal muscles, shift of the intrathoracic pressure, inspiratory occlusional pressure, and maximal rate of the initial increase in inspiratory pressure, were studied. Depending on conditions of the respiratory system functioning, any one from among the above parameters can reflect the efferent output of the respiratory center. Each of them, however, has limitations of its own.

Animals↗
PubMed1976

[Reaction of the human ventilatory apparatus to supplementary respiratory resistance upon inhalation of normo- and hypercapnic mixtures].

In 5 healthy young subjects, the intrathoracic pressure, pneumotachogram, and CO2 tension in exhaled air were recorded--under conditions of breathing with additional resistance (15 cm water/1/sec). While breathing with air, starting from the 1st respiratory cycle after switching on of the additional resistance, a respiratory regimen had been formed (decreased ventilation and increased respiratory activity) which did not alter during next 10 min. When breathing with hypercapnic mixture (4% CO2 in air), the respiratory regimen changed in two stages: a stepwise increase of respiratory activity and reducing of ventilation, and further gradual increase of these parameters. Increase in the respiratory activity was invariably followed by an increase in the CO2 alveolar tension. Role of chemo- and mechanoreceptors in formation of the ventilatory apparatus response to additional resistance against breathing, is discussed.

Adult↗
PubMed1976

[Response of the human ventilatory apparatus to additional respiratory resistance upon inhalation of normo- and hypercapnic mixtures].

In 78 healthy subjects, at 760 m (Frunze) and 3600 m (the Pamirs) above sea level, apneic points and ventilatory responses to increasing hypercapnia were assessed (rebreathing method). At 3600 m (4 to 11-month adaptation), regulation of breathing was achieved at lesser threshold CO2 values than in lowlanders, with no quantitative difference in ventilatory responses. On days 5 to 7 of deadaptation (at 760 m) following 45 days of adaptation at 3870 m, there was a decrease in ventilatory responses to a 1 mm Hg increment in PACO2, while apneic point values approached base-line values (prior to ascent to the high altitude).

Adaptation, Physiological↗