Role of the chest wall in detection of added elastic loads

1990 ◽  
Vol 68 (5) ◽  
pp. 2241-2245 ◽  
Author(s):  
M. Younes ◽  
D. Jung ◽  
A. Puddy ◽  
G. Giesbrecht ◽  
R. Sanii
Keyword(s):  
Chest Wall ◽  
Respiratory Muscles ◽  
Primary Source ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Convincing Evidence ◽  
The Body ◽  
Positive Pressure ◽  
Load Detection ◽  
Source Of Information

Changes in respiratory mechanical loads are readily detected by humans. Although it is widely believed that respiratory muscle afferents serve as the primary source of information for load detection, there is, in fact, no convincing evidence to support this belief. We developed a shell that encloses the body, excluding the head and neck. A special loading apparatus altered pressure in proportion to respired volume (elastic load) in one of three ways: 1) at the mouth only (T), producing a conventional load in which respiratory muscles are loaded and airway and intrathoracic pressures are made negative in proportion to volume, 2) both at the mouth and in the shell (AW), where the same pattern of airway and intrathoracic pressure occurs but the muscles are not loaded because Prs (i.e., mouth pressure minus pressure in the shell is unchanged, and 3) positive pressure in proportion to volume at the shell only, loading the chest wall but causing no change in airway or thoracic pressures (CW). The threshold for detection (delta E50) with the three types of application was determined in seven normal subjects: 2.16 +/- 0.22, 2.65 +/- 0.54, and 6.21 +/- 0.85 (SE) cmH2O/l for T, AW, and CW, respectively. Therefore the active chest wall, including muscles, is a much less potent source of information than structures affected by the negative airway and intrathoracic pressure. The latter account for the very low threshold for load detection.

Mechanism of detection of resistive loads in conscious humans

1992 ◽  
Vol 72 (6) ◽  
pp. 2267-2270 ◽  
Author(s):  
A. Puddy ◽  
G. Giesbrecht ◽  
R. Sanii ◽  
M. Younes
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Primary Source ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Resistive Load ◽  
Load Detection ◽  
Elastic Load ◽  
Resistive Loads ◽  
Source Of Information

Conscious humans easily detect loads applied to the respiratory system. Resistive loads as small as 0.5 cmH2O.l-1.s can be detected. Previous work suggested that afferent information from the chest wall served as the primary source of information for load detection, but the evidence for this was not convincing, and we recently reported that the chest wall was a relatively poor detector for applied elastic loads. Using the same setup of a loading device and body cast, we sought resistive load detection thresholds under three conditions: 1) loading of the total respiratory system, 2) loading such that the chest wall was protected from the load but airway and intrathoracic pressures experienced negative pressure in proportion to inspiratory flow, and 3) loading of the chest wall alone with no alteration of airway or intrathoracic pressure. The threshold for detection for the three types of load application in seven normal subjects was 1.17 +/- 0.33, 1.68 +/- 0.45, and 6.3 +/- 1.38 (SE) cmH2O.l-1.s for total respiratory system, chest wall protected, and chest wall alone, respectively. We conclude that the active chest wall is a less potent source of information for detection of applied resistive loads than structures affected by negative airway and intrathoracic pressure, a finding similar to that previously reported for elastic load detection.

Perception of changes in breathing in normal human subjects

1981 ◽  
Vol 50 (1) ◽  
pp. 78-83 ◽  
Author(s):  
N. Wolkove ◽  
M. D. Altose ◽  
S. G. Kelsen ◽  
P. G. Kondapalli ◽  
N. S. Cherniack
Keyword(s):  
Tidal Volume ◽  
Control Volume ◽  
Human Subjects ◽  
Respiratory Muscles ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Volume Changes ◽  
Elastic Load ◽  
Normal Human ◽  
Pressure Changes

Respiratory sensation was evaluated in normal subjects from their ability to quantitate changes in tidal volume. Subjects attempted to duplicate or double tidal volumes of different sizes while breathing freely or against a resistive or elastic load. When the mechanical conditions during control and test breaths were constant, tidal volume duplication was accomplished with an error of approximately 100 ml, regardless of the control volume. The error in doubling, however, increased progressively with increasing control tidal volume. There was a greater error in both volume duplication and doubling when the mechanical conditions between control and test breaths were changed. When test breaths against a load followed unloaded control breaths, tidal volume failed to double, but intrathoracic pressure changes twice exceeded control values. Conversely, when unloaded test breaths followed loaded control breaths, pressure changes underwent less than a twofold increase while tidal volume more than doubled. The results indicate that tidal volume changes are normally sensed with considerable accuracy and suggest that both tidal volume per se, as well as the forces generated by the respiratory muscles, are used in the estimation of tidal volume changes.

Selective reflex activation of the genioglossus in humans

1990 ◽  
Vol 68 (6) ◽  
pp. 2581-2587 ◽  
Author(s):  
J. C. Leiter ◽  
J. A. Daubenspeck
Keyword(s):  
Hypoglossal Nerve ◽  
Upper Airway ◽  
Normal Subjects ◽  
The Body ◽  
Positive Pressure ◽  
Electromyographic Activity ◽  
Nerve Activity ◽  
Airway Patency ◽  
Reflex Activation ◽  
Pressure Changes

In anesthetized or decerebrate animals, negative pressure applied to the upper airway selectively activates the hypoglossal nerve compared with the phrenic nerve. Conversely, positive pressure reduces hypoglossal nerve activity out of proportion to any change in the phrenic neurogram. We have tested the hypothesis that analogous pressure changes applied to awake humans would selectively inhibit or activate genioglossal electromyographic (EMGge) activity relative to diaphragmatic electromyographic activity (EMGdi). We studied seven normal subjects in a head-out body plethysmograph. Pressure at the mouth was either atmospheric, +10 cmH2O, or -10 cmH2O, and lung volume was held constant by applying an identical pressure to the body surface. Thus the transmural pressure distorting the respiratory system was applied only to the upper airway. Subjects breathed CO2-enriched (2-3%) room air to stimulate phasic respiratory EMGge activity. We found that -10 cmH2O pressure applied selectively to the upper airway resulted in a 49% enhancement of peak-integrated EMGge activity, but EMGdi activity remained at control levels. Positive pressure did not result in any changes in EMGge or EMGdi activity. Neither pressure resulted in significant changes in the magnitude or pattern of ventilation. We conclude that reflex mechanisms maintaining upper airway patency are demonstrable in awake humans and probably have an important role in moment-to-moment modulation of upper airway muscle activity in normal awake humans.

scholarly journals Bodily emotional expressions are a primary source of information for dogs, but not for humans

2021 ◽  
Author(s):  
Catia Correia-Caeiro ◽  
Kun Guo ◽  
Daniel Mills
Keyword(s):  
Ecological Niche ◽  
Emotion Perception ◽  
Primary Source ◽  
Age Effect ◽  
The Body ◽  
Emotional Expressions ◽  
Emotional Cues ◽  
Comparative Model ◽  
Species Specific ◽  
Source Of Information

AbstractDogs have remarkable abilities to synergise their behaviour with that of people, but how dogs read facial and bodily emotional cues in comparison to humans remains unclear. Both species share the same ecological niche, are highly social and expressive, making them an ideal comparative model for intra- and inter-species emotion perception. We compared eye-tracking data from unrestrained humans and dogs when viewing dynamic and naturalistic emotional expressions in humans and dogs. Dogs attended more to the body than the head of human and dog figures, unlike humans who focused more on the head of both species. Dogs and humans also showed a clear age effect that reduced head gaze. Our results indicate a species-specific evolutionary adaptation for emotion perception, which is only partly modified for heterospecific cues. These results have important implications for managing the risk associated with human–dog interactions, where expressive and perceptual differences are crucial.

Cardiovascular responses to elevation of intra-abdominal hydrostatic pressure

1985 ◽  
Vol 248 (2) ◽  
pp. R208-R213 ◽  
Author(s):  
G. E. Barnes ◽  
G. A. Laine ◽  
P. Y. Giam ◽  
E. E. Smith ◽  
H. J. Granger
Keyword(s):  
Hydrostatic Pressure ◽  
Peritoneal Cavity ◽  
Femoral Vein ◽  
Pressure Rise ◽  
Intrathoracic Pressure ◽  
Cardiovascular Responses ◽  
The Body ◽  
Whole Body ◽  
Positive Pressure ◽  
Abdominal Pressure

Intra-abdominal fluid volume and hydrostatic pressure were elevated by positive pressure infusion of Tyrode solution into the peritoneal cavity of anesthetized dogs. The compliance of the peritoneal cavity fell from 10.8 to 0.56 ml X mmHg-1 X kg-1 of body wt as intra-abdominal pressure increased from 0 to 40 mmHg. Intrathoracic pressure also increased as elevated peritoneal pressure caused diaphragmatic bulging. Cardiac output and stroke volume were reduced by 36% after an intra-abdominal pressure rise of 40 mmHg; in contrast, heart rate did not change. Flow in the celiac, superior mesenteric, and renal arteries was reduced by 42, 61, and 70%, respectively. Pressure in the femoral vein increased to 46 mmHg, while flow in the femoral artery decreased by 65%. Whole-body O2 consuxmption, pH, and arterial PO2 decreased as intra-abdominal pressure rose. The peritoneal cavity, with its high initial compliance, affords the body an ideal location for the temporary accumulation of small to moderate volumes of fluid during episodes of increased vascular pressure or permeability. The marked alterations in the hemodynamic properties of the cardiovascular system are indicative of the physiological changes that occur when intra-abdominal fluid accumulation becomes excessive and peritoneal pressure rises to high levels.

Motion of the Rib Cage and the Abdomen in Tetraplegic Patients

1978 ◽  
Vol 54 (1) ◽  
pp. 25-32 ◽  
Author(s):  
J. P. Mortola ◽  
G. Sant' Ambrogio
Keyword(s):  
Chest Wall ◽  
Cervical Spinal Cord ◽  
Work Of Breathing ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Flow Profile ◽  
Rib Cage ◽  
Sitting Posture ◽  
Supine Posture ◽  
High Work

1. We have studied the motion of the abdomen and the rib cage in patients with a transection of the lower cervical spinal cord during normal breathing both in the supine and sitting posture, and compared it with that of normal subjects. 2. In the supine posture the rib cage of a patient moves paradoxically inward, therefore his chest wall is deformed, which explains the high work of breathing. 3. During expiration, beside the recoil of the respiratory system, there is also the recoil of the deformed chest wall, toward its passive configuration, with an expansion of the rib cage above its resting position during the first part of expiration and an alteration of the expiratory flow profile. 4. In a sitting ‘relaxed’ posture the paradoxical inward motion disappears in the lower rib cage, and it is reduced but still present in the higher rib cage. 5. We conclude that contraction of the diaphragm constricts the ‘passive rib cage’, either directly through its insertions or indirectly through the reduction of intrathoracic pressure. In seated subjects the diaphragm causes some expansion of the rib cage at its lower level. Therefore the motion of the rib cage is not only related to the balance between the forces developed by the diaphragm and the intercostal muscles, but also to the diaphragm dome configuration, the geometry of the rib cage and the lung volume.

THE EFFICIENCY OF THE RESPIRATORY MUSCLES IN OBESITY

1961 ◽  
Vol 39 (8) ◽  
pp. 1215-1222 ◽  
Author(s):  
Reuben M. Cherniack ◽  
Clarence A. Guenter
Keyword(s):  
Chest Wall ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Oxygen Cost ◽  
Chest Wall Compliance ◽  
Elastic Resistance ◽  
Lower Lung ◽  
Wall Compliance ◽  
Obese Subjects ◽  
Work Done

The work done to overcome the elastic resistance and the efficiency of the respiratory muscles were determined in normal and obese subjects. The work done was no greater in the obese subjects, but the efficiency of the muscles was low. These findings suggest that the high oxygen cost of breathing in obesity is due to inefficient respiratory muscles rather than to an increased amount of work required to overcome elastic resistance. When an extrapulmonary elastic resistance was applied to the normal subjects, the compliance of the chest wall and the efficiency of the respiratory muscles fell to the level of that in the obese. This suggests that the inefficiency of the respiratory muscles of obese individuals may have been due to the reduced chest wall compliance or to the lower lung volume at which ventilation took place.

Effect of respiratory muscle tension on lung volume

1992 ◽  
Vol 73 (6) ◽  
pp. 2283-2288 ◽  
Author(s):  
T. A. Wilson ◽  
A. De Troyer
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Airway Pressure ◽  
Linear Prediction ◽  
Muscle Tension ◽  
Muscle Length ◽  
Respiratory Muscles ◽  
Active Tension ◽  
Airway Opening ◽  
Measured Change

The chest wall is modeled as a linear system for which the displacements of points on the chest wall are proportional to the forces that act on the chest wall, namely, airway opening pressure and active tension in the respiratory muscles. A standard theorem of mechanics, the Maxwell reciprocity theorem, is invoked to show that the effect of active muscle tension on lung volume, or airway pressure if the airway is closed, is proportional to the change of muscle length in the relaxation maneuver. This relation was tested experimentally. The shortening of the cranial-caudal distance between a rib pair and the sternum was measured during a relaxation maneuver. These data were used to predict the respiratory effect of forces applied to the ribs and sternum. To test this prediction, a cranial force was applied to the rib pair and a caudal force was applied to the sternum, simulating the forces applied by active tension in the parasternal intercostal muscles. The change in airway pressure, with lung volume held constant, was measured. The measured change in airway pressure agreed well with the prediction. In some dogs, nonlinear deviations from the linear prediction occurred at higher loads. The model and the theorem offer the promise that existing data on the configuration of the chest wall during the relaxation maneuver can be used to compute the mechanical advantage of the respiratory muscles.

Nutrient supplementation among pregnant women in China: an observational study

2021 ◽  
pp. 1-19
Author(s):  
Tao Han ◽  
Jingwen Dong ◽  
Jiangtao Zhang ◽  
Chenxiao Zhang ◽  
Yuxuan Wang ◽  
...  
Keyword(s):  
Vitamin D ◽  
Folic Acid ◽  
Pregnant Women ◽  
Family Members ◽  
Primary Source ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Nutrient Supplementation ◽  
Face To Face ◽  
Source Of Information

Abstract Objective: To clarify nutrient supplementation usage and primary source of information among pregnant women in China. Design: This cross-sectional study used information on nutrient supplementation and primary source of information collected via face-to-face interviews. Data on the usage of folic acid, calcium/vitamin D, iron, vitamins, docosahexaenoic acid, and other dietary supplements were collected. Primary source of information were categorized as family/relatives, friends/co-workers, the Internet, books/magazines, television/radio, doctors, other people, and oneself. Setting: Maternal and Child Health Hospital in Chengdu, China. Participants: 1081 Chinese pregnant women aged ≥ 20 years with singleton pregnancies. Results: In all three trimesters of pregnancy, usage was highest and most stable for folic acid (81.7%), followed by vitamins (vitamin A, B-group vitamins, vitamin C, and multivitamins; 75.0%), whereas calcium/vitamin D (51.4%) and iron (18.1%) usage was low, potentially indicating a deficiency risk. All supplementation usage percentages increased with pregnancy duration (p < 0.05). Notably, approximately 10% of the pregnant women in our study did not use any nutrient supplementation, and this was especially common in early pregnancy. More than 50% of the women reported getting information on nutrient supplementation from family members, and about 30% reported getting this information from doctors. Conclusions: Among pregnant women in China, awareness about nutrient supplementation increases as the pregnancy progresses, but some types of nutrient supplementation (such as calcium/vitamin D and iron) remain at low levels. It is necessary to pay more attention to the health education of pregnant women in China, and the influence of family members should be emphasized.

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