Control of respiratory frequency

1960 ◽  
Vol 15 (3) ◽  
pp. 325-336 ◽  
Author(s):  
Jere Mead
Keyword(s):  
Guinea Pig ◽  
Respiratory System ◽  
Mechanical Characteristics ◽  
Control Mechanism ◽  
Respiratory Muscles ◽  
Alveolar Ventilation ◽  
Respiratory Frequency ◽  
Average Force ◽  
Natural Breathing

Previous work has shown that for a given level of alveolar ventilation there is a particular respiratory frequency which is least costly in terms of respiratory work. There is also a particular frequency, usually a different one, which is least costly in terms of average force of the respiratory muscles. Evidence is presented that in the resting guinea pig and in man at rest and during exercise natural breathing takes place at frequencies approximating the second optimum. From additional observations on the effects of changing the mechanical characteristics of the respiratory system on respiratory frequency it is concluded that the principal site of the sensory end of the control mechanism is in the lungs. Submitted on November 19, 1959

Quantification of nasal involvement in a guinea pig plethysmograph

1994 ◽  
Vol 76 (4) ◽  
pp. 1432-1438 ◽  
Author(s):  
M. J. Finney ◽  
K. I. Forsberg
Keyword(s):  
Lung Function ◽  
Guinea Pig ◽  
Respiratory System ◽  
Guinea Pigs ◽  
Repeated Measurement ◽  
Whole Body ◽  
Nasal Resistance ◽  
Rapid Technique ◽  
Respiratory System Resistance ◽  
Lower Airways

We have developed a technique for measuring lung function in conscious guinea pigs using a whole body plethysmograph. Because guinea pigs breathe through the nose, a technique was also developed to measure nasal and lower respiratory system conductance simultaneously in anesthetized animals. The upper and the lower airways could be challenged separately and studied in a manner similar to the conditions in the plethysmograph. Aerosols of histamine, carbachol, or ovalbumin delivered to the nose in sensitized animals had no effect on nasal conductance, even in doses 100 times higher than that required to reduce lower respiratory system conductance. However, intravenous histamine increased nasal conductance. Thus, although nasal resistance constitutes the majority of the total respiratory system resistance measured in the plethysmograph, nasal resistance is unaffected by the aerosol drugs studied. We therefore consider changes in resistance measured in the plethysmograph to originate at or below the larynx. The plethysmographic technique described here is a reliable, reproducible, and rapid technique that enables repeated measurement in animals and minimizes animal trauma.

Intraretinal oxygen distribution and choroidal regulation in the avascular retina of guinea pigs

1996 ◽  
Vol 270 (3) ◽  
pp. H965-H973 ◽  
Author(s):  
D. Y. Yu ◽  
S. J. Cringle ◽  
V. A. Alder ◽  
E. N. Su ◽  
P. K. Yu
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Regulatory Mechanism ◽  
Control Mechanism ◽  
Inner Retina ◽  
Arterial Blood ◽  
Rapid Changes ◽  
Mammalian Retina ◽  
O2 Distribution ◽  
Normal Ventilation

O2-sensitive microelectrodes were used to measure PO2 as a function of depth through the retina and choroid of anesthetized and artificially ventilated guinea pigs. The guinea pig retina is of particular interest, because it has a typically mammalian structure but no retinal circulation; it relies totally on choroidal delivery of O2 and other nutrients. Measurements of intraretinal O2 distribution in an avascular mammalian retina have not previously been reported. Under normal ventilation conditions, PO2 decreased monotonically from the choroid (33.6 +/- 2.9 mmHg, n = 11) to near zero (0.4 +/- 0.1 mmHg) at the retina-vitreous boundary. The inner half of the retina had an average PO2 of only 0.6 +/- 0.1 mmHg. Stepwise increases in inspired O2 (from 20 to 40 to 60 to 80 to 100%) had surprisingly little effect on choroidal PO2. Rapid changes (20-100%) produced overshoot-type responses in the choroid before recovery to levels only slightly above those found in normoxia. This indicates the presence of an active O2-regulatory mechanism in the guinea pig choroid. Addition of CO2 (5%) to O2 ventilation appeared to break down this control mechanism and led to dramatic and sustained increases in PO2 throughout the retina and choroid. The demonstration of an O2-regulating mechanism in the guinea pig choroid that maintains choroidal PO2 well below that in the systemic arterial blood, coupled with the observation of very low O2 levels throughout the inner retina, suggests that the O2 requirement of the inner retina in the guinea pig is small and that O2 levels in the choroid are deliberately constrained.

Effect of simulated breath sounds on ventilation

1964 ◽  
Vol 19 (2) ◽  
pp. 233-235 ◽  
Author(s):  
M. Henry Williams ◽  
Cecile Kane
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Normal Subjects ◽  
Alveolar Ventilation ◽  
Respiratory Frequency ◽  
Auditory Stimuli ◽  
Chronic Obstructive ◽  
Breathing Rate ◽  
Obstructive Pulmonary Disease ◽  
Breath Sounds

When normal subjects listened to simulated breath sounds while breathing at their natural respiratory frequency there was a significant decrease of alveolar Pco2. The alveolar Pco2 did not fall further when these subjects listened to the simulator and breathed slowly, but when they breathed with the simulator at a very rapid frequency there was further fall of the PaCOCO2. When patients with chronic obstructive pulmonary disease listened to simulated breath sounds while breathing at their natural respiratory frequency there was a decrease of arterial Pco2 which fell further when the subjects breathed with the simulator at a slow respiratory rate. breathing, effect of auditory stimuli on; breathing rate and pulmonary function on chronic obstructive pulmonary disease; alveolar ventilation and auditory respiratory stimuli; respiratory frequency and ventilation Submitted on July 12, 1963

scholarly journals Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise?

2020 ◽  
Vol 129 (6) ◽  
pp. 1235-1256 ◽  
Author(s):  
Jerome A. Dempsey ◽  
Andre La Gerche ◽  
James H. Hull
Keyword(s):  
Respiratory System ◽  
Exercise Performance ◽  
Respiratory Muscles ◽  
Lung Parenchyma ◽  
Endurance Athletes ◽  
Pulmonary Vasculature ◽  
Blood Gas ◽  
Ventilatory Control ◽  
Response To Exercise ◽  
Homeostatic Response

In the healthy, untrained young adult, a case is made for a respiratory system (airways, pulmonary vasculature, lung parenchyma, respiratory muscles, and neural ventilatory control system) that is near ideally designed to ensure a highly efficient, homeostatic response to exercise of varying intensities and durations. Our aim was then to consider circumstances in which the intra/extrathoracic airways, pulmonary vasculature, respiratory muscles, and/or blood-gas distribution are underbuilt or inadequately regulated relative to the demands imposed by the cardiovascular system. In these instances, the respiratory system presents a significant limitation to O2 transport and contributes to the occurrence of locomotor muscle fatigue, inhibition of central locomotor output, and exercise performance. Most prominent in these examples of an “underbuilt” respiratory system are highly trained endurance athletes, with additional influences of sex, aging, hypoxic environments, and the highly inbred equine. We summarize by evaluating the relative influences of these respiratory system limitations on exercise performance and their impact on pathophysiology and provide recommendations for future investigation.

Mathematical modeling of processes in the human respiratory system

2015 ◽  
Vol 9 (2) ◽  
pp. 0-0 ◽  
Author(s):  
Канунникова ◽  
A. Kanunnikova ◽  
Ивахно ◽  
N. Ivakhno ◽  
Федоров ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mass Flow ◽  
Respiratory System ◽  
Breathing Circuit ◽  
Stress Component ◽  
Respiratory Muscles ◽  
Axial Direction ◽  
Flow Diagram ◽  
Cylinder Wall ◽  
Human Respiratory System

Scientific relevance and purpose. This research looks at the urgent task of modeling the structure of the human respiratory system and processes occurring in it, in order to predict the changes in physiological parameters occurring under different mechanical actions. Results. This paper suggests mathematical model based on the description of equations of the mass flow and mass flow rate in the pulmonary channels in cases, when airways are branched in accordance with the prin-ciple of regular dichotomy with regard to the equations of work dynamics of the respiratory muscles and the ability to model different stresses in the breathing circuit, caused by trainers. The research examined the stresses generated by muscles in the radial and axial direction of the equivalent hollow cylinder, which represented the chest with regard to the elastic stress component in the cylinder wall and variable muscle stress in the circumfe-rential direction. The paper contains the results of mathematical modeling of breathing without stress, the graphs of volume and mass flow in lungs generations and pressure-flow diagram. Conclusions. The developed mathematical models enable more precise multi-parameter modeling of the dynamics of functioning of complex biotech system "respiratory muscles trainer - human", which enables the implementation of the prediction of shifts of physiological and mechanical properties from the values of the normal process and to adjust the control actions on this basis

Developmental changes in chest wall compliance in infancy and early childhood

1995 ◽  
Vol 78 (1) ◽  
pp. 179-184 ◽  
Author(s):  
C. Papastamelos ◽  
H. B. Panitch ◽  
S. E. England ◽  
J. L. Allen
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Respiratory Muscles ◽  
Lung Compliance ◽  
Developmental Changes ◽  
System Function ◽  
Manual Ventilation ◽  
Chest Wall Compliance ◽  
Wall Stiffness ◽  
Wall Compliance

Development of chest wall stiffness between infancy and adulthood has important consequences for respiratory system function. To test the hypothesis that there is substantial stiffening of the chest wall in the first few years of life, we measured passive chest wall compliance (Cw) in 40 sedated humans 2 wk-3.5 yr old. Respiratory muscles were relaxed with manual ventilation applied during the Mead-Whittenberger technique. Respiratory system compliance (Crs) and lung compliance (Cl) were calculated from airway opening pressure, transpulmonary pressure, and tidal volume. Cw was calculated as 1/Cw = 1/Crs - 1/Cl during manual ventilation. Mean Cw per kilogram in infants < 1 yr old was significantly higher than that in children > 1 yr old (2.80 +/- 0.87 vs. 2.04 +/- 0.51 ml.cmH2O–1.kg-1; P = 0.002). There was an inverse linear relationship between age and mean Cw per kilogram (r = -0.495, slope -0.037; P < 0.001). In subjects with normal Cl during spontaneous breathing, Cw/spontaneous Cl was 2.86 +/- 1.06 in infants < 1 yr old and 1.33 +/- 0.36 in older children (P = 0.005). We conclude that in infancy the chest wall is nearly three times as compliant as the lung and that by the 2nd year of life chest wall stiffness increases to the point that the chest wall and lung are nearly equally compliant, as in adulthood. Stiffening of the chest wall may play a major role in developmental changes in respiratory system function such as the ability to passively maintain resting lung volume and improved ventilatory efficiency afforded by reduced rib cage distortion.

scholarly journals A study of histological changes in the Diaphragm of male albino mice administered with aqueous extract of chamomileflowers Chamomillarecutita

2017 ◽  
Vol 14 (3) ◽  
pp. 489-496
Author(s):  
Baghdad Science Journal
Keyword(s):  
Medicinal Plants ◽  
Aqueous Extract ◽  
Muscle Fiber ◽  
Respiratory System ◽  
Respiratory Muscles ◽  
Control Group ◽  
Histological Structure ◽  
Muscular Tissue ◽  
Histological Changes ◽  
Albino Mice

The chamomile is one of the most important medicinal plants recommended for treatment of asthma and some respiratory system diseases. This research was designed to research the effects of aqueous extract of chamomillarecutita on histological structure of Diaphragm of albino mice. The study included 40 male albino mice Musmusculus, their age ranged from (5-7) weeks.The mices were divided randomly to 5 groups and oral administered with 1 ml every day for 10 days:- First Group G1: consider as control group and treated with normal saline,Second Group G2: was treated with aqueous extract of chamomile with concentration of 3 gm /100 ml D.W, Third Group G3: was treated with aqueous extract of chamomile with concentration of 5 gm /100 ml D.W.Fourth Group G4: was treated with aqueous extract of chamomile with concentration of 7 gm /100 ml D.W and the Fifth Group G5: was treated with aqueous extract of chamomile with concentration of 10 gm /100 ml D.W. Theresults of microscopic examination of diaphragm sections of groups G3,G4 and G5 showed degenerative effects on muscular tissue in way of breaking of myofibrils differences in their sizes and degeneration of most of nuclei of muscle fiber and their migration to inside the muscle fiber , it has been found that these treatments cause an alteration in myofibril in fibrotic myofibril. From this study we conclude that low concentration of aqueous extract of chamomile have low side effect on major respiratory muscles and could be used in beneficial treatment to contact diseases of respiratory system but without longer duration.

Pulmonary disease and anaesthesia

2017 ◽  
Author(s):  
Gary H. Mills
Keyword(s):  
Critical Care ◽  
Respiratory Disease ◽  
Respiratory System ◽  
Respiratory Muscles ◽  
Postoperative Recovery ◽  
Respiratory Support ◽  
Normal Lung ◽  
High Incidence ◽  
Risk Patients ◽  
The Right

Respiratory adverse events are the commonest complications after anaesthesia and have profound implications for the recovery of the patient and their subsequent health. Outcome prediction related to respiratory disease and complications is vital when determining the risk:benefit balance of surgery and providing informed consent. Surgery produces an inflammatory response and pain, which affects the respiratory system. Anaesthesia produces atelectasis, decreases the drive to breathe, and causes muscle weakness. As the respiratory system ages, closing capacity increases and airway closure becomes an increasing issue, resulting in atelectasis. Increasing comorbidity and polypharmacy reduces the patient’s ability to eliminate drugs. The proportion of major operations on older frailer patients is rising and postoperative recovery becomes more complicated and the demand for critical care rises. At the same time, the population is becoming more obese, producing rapid decreases in end-expiratory lung volume on induction, together with a high incidence of sleep-disordered breathing. Despite this, many high-risk patients are not accurately identified preoperatively, and of those that are admitted to critical care, some are discharged and then readmitted to the intensive care unit with complications. Respiratory diseases may lead to increases in pulmonary vascular resistance and increased load on the right heart. Some lung diseases are primarily fibrotic or obstructive. Some are inflammatory, autoimmune, or vasculitic. Other diseases relate to the drive to breathe, the nerve supply to, or the respiratory muscles themselves. The range of types of respiratory disease is wide and the physiological consequences of respiratory support are complex. Research continues into the best modes of respiratory support in theatre and in the postoperative period and how best to protect the normal lung. It is therefore essential to understand the effects of surgery and anaesthesia and how this impacts existing respiratory disease, and the way this affects the balance between load on the respiratory system and its capacity to cope.

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