Effect of forward acceleration and negative pressure breathing on pulmonary diffusion

1962 ◽  
Vol 17 (6) ◽  
pp. 909-912
Author(s):  
Fred Zechman ◽  
Gustave Mueller
Keyword(s):  
Negative Pressure ◽  
Technical Assistance ◽  
Human Subjects ◽  
Pulmonary Ventilation ◽  
Pressure Curve ◽  
Experimental Conditions ◽  
Lung Volumes ◽  
Control Value ◽  
Negative Pressure Breathing ◽  
The Right

Forward acceleration decreases lung volumes, resembling negative pressure breathing (NPB). At 4 g the relaxation pressure curve is shifted downward and to the right 15 mm Hg. Pulmonary gas exchange and diffusion capacity were measured in nine human subjects during NPB (-15 mm Hg) and forward acceleration (4 g). Pulmonary ventilation increased approximately 40% in each condition. The O2 uptake increased with NPB (from 261 to 293 ml/min) and was slightly decreased or unchanged at 4 g. Carbon dioxide elimination increased in both experimental conditions. The apparent steady-state Dco was unchanged by NPB but decreased from an average control value of 21 to 12 ml/min mm Hg at 4 g. Since lung volumes are decreased by comparable amounts in both conditions, it is believed that the deleterious effects observed with forward acceleration are associated with the increased hydrostatic gradient from chest to back. Note: (With the Technical Assistance of Justin Taylor) Submitted on June 4, 1962

ON VARIATIONS OF HUMAN HEMODYNAMIC PARAMETERS CAUSED BY NEGATIVE PRESSURE BREATHING DURING 15-HOUR HEAD-DOWN TILT

2021 ◽  
Vol 55 (6) ◽  
pp. 34-41
Author(s):  
Yu.S. Semenov ◽  
◽  
А.А. Gorbunova ◽  
A.I. Dyachenko ◽  
◽  
...  
Keyword(s):  
Negative Pressure ◽  
Human Subjects ◽  
Free Breathing ◽  
The Other ◽  
Hemodynamic Parameters ◽  
Cardiovascular Parameters ◽  
Averaging Technique ◽  
Cardiovascular Reaction ◽  
Coherent Averaging ◽  
Negative Pressure Breathing

The cardiovascular reaction to negative pressure breathing (NPB) was studied in human subjects in the condition of 15-hour head-down tilt (-15°). Amplitude and time characteristics of tidal oscillations of physiological parameters synchronous to free and NPB breathing were measured after 14 hours in HDT. Oscillations of cardiovascular parameters were determined using the coherent averaging technique. A multiple increase in amplitude was stated during transition from free breathing to NPB, whereas variations of the other characteristics of oscillations were little affected.

Responses to continuous negative-pressure breathing in man at rest and during exercise

1980 ◽  
Vol 48 (6) ◽  
pp. 977-981 ◽  
Author(s):  
H. Bjurstedt ◽  
G. Rosenhamer ◽  
C. M. Hesser ◽  
B. Lindborg
Keyword(s):  
Negative Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Carbon Dioxide Tension ◽  
Minute Volume ◽  
Left Ventricular ◽  
Circulatory Effects ◽  
Ventricular Afterload ◽  
Negative Pressure Breathing ◽  
The Right

We studied the respiratory and circulatory effects in six healthy supine volunteers of continuous negative-pressure breathing (CNPB) at -15 and -30 cmH2O at rest and during dynamic leg exercies at 50% of individual working capacity. CNPB had no significant effects on respiratory minute volume, tidal volume, or arterial carbon dioxide tension. Mean arterial pressure remained essentially unchanged both at rest and during exercise, signifying that the reductions in intrathoracic pressure caused corresponding increases in left ventricular afterload. Nevertheless, cardiac output increased significantly in both conditions, causing reductions of mean central venous pressure that were considerably greater during exercise than at rest. These responses were reflected by increments in left ventricular work, amounting to 24 and 20% at rest and during exercise, respectively, at -30 cmH2O. We conclude that in CNPB at rest the increased activity of the left ventricle with associated juxtathoracic venous collapse protects the right heart and pulmonary circulation from congestion and that it does so even more effectively during exercise.

Lung volumes, lung compliance and airway resistance during negative-pressure breathing

1960 ◽  
Vol 15 (4) ◽  
pp. 554-556 ◽  
Author(s):  
E. Y. Ting ◽  
S. K. Hong ◽  
H. Rahn
Keyword(s):  
Negative Pressure ◽  
Airway Resistance ◽  
Lung Compliance ◽  
Positive Pressure ◽  
Lung Volumes ◽  
Volume Curve ◽  
Supine Posture ◽  
Pressure Volume Curve ◽  
Esophageal Balloon ◽  
Negative Pressure Breathing

Lung volumes, airflow resistance and lung elastance were measured in seven subjects during various degrees of continuous negative-pressure breathing in the supine posture. At –30 cm H2O the expiratory reserve is reduced to about 30% of its normal value and the resistance to airflow is more than doubled. On the other hand, the pressure-volume curve of the lung measured with the aid of an esophageal balloon was not significantly altered by either negative-pressure or positive-pressure breathing. Submitted on February 8, 1960

Effect of forward acceleration on renal function

1962 ◽  
Vol 17 (3) ◽  
pp. 413-416 ◽  
Author(s):  
John F. Watson ◽  
Rita M. Rapp
Keyword(s):  
Negative Pressure ◽  
Human Subjects ◽  
Renal Plasma Flow ◽  
Urine Volume ◽  
Free Water ◽  
Free Water Clearance ◽  
Water Excretion ◽  
Normal Human ◽  
Negative Pressure Breathing ◽  
Water Clearance

The effect of forward acceleration on renal hemodynamics, electrolyte excretion, and water clearance has been studied in six normal human subjects. Forward acceleration produced a slight increase in glomerular filtration rate and effective renal plasma flow during and after stress. After centrifugation there was a 20–35-min lag before the appearance of an increase in urine volume and free water clearance. These changes in water excretion were transient and were not accompanied by a natriuresis nor associated with changes in serum osmolality. Physiologic responses to forward acceleration and negative pressure breathing were compared. It was suggested that forward acceleration, like negative pressure breathing, may induce an increase in intrathoracic blood volume which inhibits the release of antidiuretic hormone via a nonosmotic volume-sensitive receptor mechanism located within the intrathoracic vascular space. Submitted on September 14, 1961

Factors Influencing Alveolar-Arterial Oxygen Pressure Gradient

1956 ◽  
Vol 186 (3) ◽  
pp. 501-504 ◽  
Author(s):  
Robert J. Atwell ◽  
Joseph F. Tomashefski ◽  
Joseph M. Ryan
Keyword(s):  
Pressure Gradient ◽  
Oxygen Pressure ◽  
Negative Pressure ◽  
Pulmonary Ventilation ◽  
Arterial Oxygen ◽  
Venous Admixture ◽  
Factors Influencing ◽  
Anesthetized Dogs ◽  
Negative Pressure Breathing ◽  
Alveolar Oxygen

The A-a oxygen pressure gradient was determined in anesthetized dogs. Data obtained when pulmonary ventilation and alveolar oxygen tension are varied independently suggests that: a) the magnitude of the A-a oxygen pressure gradient correlates directly with the Paoo2. b) In the anesthetized dog venous admixture seems to be constant, unrelated to the changes in ventilation produced by positive-negative pressure breathing. c) Venous admixture is the most important factor in producing the A-a gradient in the dog.

Dual Intentional Agency

2018 ◽  
Author(s):  
Elizabeth Schechter
Keyword(s):  
Left Hemisphere ◽  
Practical Reasoning ◽  
Right Hemisphere ◽  
Brain Surgery ◽  
Experimental Conditions ◽  
Split Brain ◽  
Intentional Agency ◽  
Intentional Agents ◽  
Experimental Findings ◽  
The Right

This chapter defends the 2-agents claim, according to which the two hemispheres of a split-brain subject are associated with distinct intentional agents. The empirical basis of this claim is that, while both hemispheres are the source or site of intentions, the capacity to integrate them in practical reasoning no longer operates interhemispherically after split-brain surgery. As a result, the right hemisphere-associated agent, R, and the left hemisphere-associated agent, L, enjoy intentional autonomy from each other. Although the positive case for the 2-agents claim is grounded mainly in experimental findings, the claim is not contradicted by what we know of split-brain subjects’ ordinary behavior, that is, the way they act outside of experimental conditions.

scholarly journals Behavioral Triggers of Skin Conductance Responses and Their Neural Correlates in the Primate Amygdala

2009 ◽  
Vol 101 (4) ◽  
pp. 1749-1754 ◽  
Author(s):  
Christopher M. Laine ◽  
Kevin M. Spitler ◽  
Clayton P. Mosher ◽  
Katalin M. Gothard
Keyword(s):  
Skin Conductance ◽  
Single Unit ◽  
Population Level ◽  
Emotional Reaction ◽  
Neural Population ◽  
Experimental Conditions ◽  
Indirect Measure ◽  
Skin Conductance Responses ◽  
The Right ◽  
Sympathetic Arousal

The amygdala plays a crucial role in evaluating the emotional significance of stimuli and in transforming the results of this evaluation into appropriate autonomic responses. Lesion and stimulation studies suggest involvement of the amygdala in the generation of the skin conductance response (SCR), which is an indirect measure of autonomic activity that has been associated with both emotion and attention. It is unclear if this involvement marks an emotional reaction to an external stimulus or sympathetic arousal regardless of its origin. We recorded skin conductance in parallel with single-unit activity from the right amygdala of two rhesus monkeys during a rewarded image viewing task and while the monkeys sat alone in a dimly lit room, drifting in and out of sleep. In both experimental conditions, we found similar SCR-related modulation of activity at the single-unit and neural population level. This suggests that the amygdala contributes to the production or modulation of SCRs regardless of the source of sympathetic arousal.

STUDIES ON HABITUATION TO COLD PAIN

1966 ◽  
Vol 44 (2) ◽  
pp. 287-293 ◽  
Author(s):  
Jacques LeBlanc ◽  
Pierre Potvin
Keyword(s):  
Cold Water ◽  
Mental Arithmetic ◽  
Blood Pressure Response ◽  
Human Subjects ◽  
Cold Pain ◽  
Left Hand ◽  
Water Test ◽  
The Difference ◽  
The Right ◽  
Habituation To Cold

It was possible to produce habituation to cold in a group of human subjects by immersing the left hand in cold water for [Formula: see text] minutes twice a day for 19 days. The right hand did not adapt. Another group of subjects was exposed similarly with the difference that an anxiety test (mental arithmetic test) was always given simultaneously with the cold-water test. In this second group the original blood pressure response, i.e. for the first day, was greater than in the first group because of the cumulative effects of the two tests. After 19 days definite evidence was obtained for adaptation to these two tests administered together. However, when these tests were given separately to the second group, no adaptation was evident; adaptation occurred only to both tests given simultaneously. These results indicate that no adaptation develops to cold per se if the subjects are distracted from cold discomfort. It was also found that adaptation of one hand to cold water not only failed to induce adaptation in the opposite hand but even reinforced responses of the unadapted hand. These findings suggest a participation of the central nervous system in adaptation to cold pain, and tend to minimize the importance of local peripheral changes.

Inhibition of cardiac vagal component of baroreflex by group III and IV afferents

1991 ◽  
Vol 260 (3) ◽  
pp. H730-H734 ◽  
Author(s):  
P. N. McWilliam ◽  
T. Yang
Keyword(s):  
Peroneal Nerve ◽  
Baroreceptor Reflex ◽  
Interval Prolongation ◽  
Group Iii ◽  
Control Value ◽  
Pressure Elevation ◽  
Group I ◽  
Afferent Fibers ◽  
The Difference ◽  
The Right

The action of electrically evoked activity in somatic afferent fibers on the sensitivity of the baroreceptor reflex was examined in decerebrate cats. The sensitivity of the reflex was expressed as the difference between the maximum prolongation of R-R interval in response to carotid sinus pressure elevation and the mean of 10 R-R intervals immediately before pressure elevation. The control value of R-R interval prolongation was 192 +/- 50 ms. Stimulation (10 Hz) of group I and II fibers of the right peroneal nerve (evoked volleys recorded from the sciatic nerve) had no effect on R-R interval prolongation (171 +/- 45 ms). Recruitment of group III fibers (10 Hz) conducting at 23.6 +/- 0.65 m/s reduced the prolongation of R-R interval to 52 +/- 14 ms. Recruitment of group IV fibers (10 Hz) conducting less than 2.5 m/s further reduced the prolongation of R-R interval to 1.0 +/- 8.0 ms. It is concluded that the inhibition of the cardiac vagal component of the baroreceptor reflex produced by electrical stimulation of the peroneal nerve is mediated by afferent fibers of groups III and IV.

An experimental study of strongly nonlinear waves in a rotating system

1987 ◽  
Vol 177 ◽  
pp. 381-394 ◽  
Author(s):  
Dominique P. Renouard ◽  
Gabriel Chabert D'Hières ◽  
Xuizhang Zhang
Keyword(s):  
Equilibrium Shape ◽  
Scaling Law ◽  
Maximum Amplitude ◽  
Rotating Platform ◽  
Coriolis Parameter ◽  
Rotating System ◽  
Height Variation ◽  
Experimental Conditions ◽  
Strongly Nonlinear ◽  
The Right

The influence of rotation upon internal solitary waves is studied in a (10 m × 2 m × 0.6 m) channel located on the large rotating platform at Grenoble University. We observe an intumescence which moves along the right-hand side of the channel with respect to its direction of propagation. Along the side, once the intumescence reaches its equilibrium shape, the height variation of the interface with time is correctly described by the sech2 function, and the characteristic KdV scaling law linking the maximum amplitude and the wavelength along the side is fulfilled. The intumescence is a stable phenomenon which moves as a whole without deformation apart from the viscous damping. For identical experimental conditions, the amplitude of the intumescence along the side increases with increasing Coriolis parameter, and at a given period of rotation of the platform, the celerity along the side increases with increasing amplitude. But for identical conditions, we found that the celerity along the side is equal to the celerity that the wave would have for such conditions without rotation. The amplitude of the intumescence in a plane perpendicular to the wall decreases exponentially with increasing distance from the side, but the crest of the wave is curved backward.

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