USING NONLINEAR RESPIRATORY MECHANICS TO OPTIMIZE THE RESPIRATORY SIGNALS UNDER EUCAPNIC AND HYPERCAPNIC CONDITIONS

2015 ◽  
Vol 39 (3) ◽  
pp. 515-525
Author(s):  
Shyan-Lung Lin ◽  
Hsing-Cheng Chang ◽  
Yu-Zhe Tsai
Keyword(s):  
Flow Resistance ◽  
Respiratory Mechanics ◽  
Normal Load ◽  
Respiratory Control ◽  
Resistive Load ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Ventilatory Responses ◽  
System A ◽  
Flow Through

In this study, the optimal chemical-mechanical respiratory control model was modified to include nonlinear respiratory mechanics with a lumped viscous resistance of the flow through the entire respiratory system, and a flow resistance that is proportional to the power of the flow rate. To evaluate the optimality of the system, a quadratic rising neuromuscular drive was applied to a neuro-mechanical effector and the respiratory signals were optimized under hypercapnia and eucapnia conditions. A continuous resistive load was imposed to compare the model behavior of respiratory mechanical loading with normal load. The optimized respiratory signals were demonstrated and the ventilatory responses with the optimized breathing patterns were examined. Our results showed that the nonlinear model acquired the intended level of ventilation with higher tidal volume VT and lower breathing frequency F during CO2 inhalation and lower VT and higher F during exercise.

Adaptation in the respiratory control system

2003 ◽  
Vol 81 (8) ◽  
pp. 765-773 ◽  
Author(s):  
James Duffin ◽  
Safraaz Mahamed
Keyword(s):  
Experimental Data ◽  
Control System ◽  
Steady State ◽  
Graphical Model ◽  
Respiratory Control ◽  
Ventilatory Responses ◽  
System A ◽  
Hypoxia Adaptation ◽  
Peripheral Chemoreflex

Exposure to hypoxia, whether for short or prolonged periods or for repeated episodes, produces alterations in the ventilatory responses. This review presents evidence that these adaptations are likely to be mediated by adaptations in the respiratory chemoreflexes, particularly the peripheral chemoreflex, and proposes models of respiratory control explaining the observed changes in ventilation. After a brief introduction to the respiratory control system, a graphical model is developed that illustrates the operation of the system in the steady state, which will be used later. Next, the adaptations in ventilatory responses to hypoxia that have been observed are described, and methods of measuring the alterations in the chemoreflexes that might account for them are discussed. Finally, experimental data supporting the view that changes in the activity of the peripheral chemoreflex can account for the ventilatory adaptations to hypoxia are presented and incorporated into models of chemoreflex behaviour during exposures to hypoxia of various durations.Key words: respiration, chemoreflexes, hypoxia, adaptation, models.

Effects of acute controlled exposure to SO2 on respiratory mechanics in healthy male adults

1962 ◽  
Vol 17 (2) ◽  
pp. 252-258 ◽  
Author(s):  
N. Robert Frank ◽  
Mary O. Amdur ◽  
Jane Worcester ◽  
James L. Whittenberger
Keyword(s):  
Flow Resistance ◽  
Technical Assistance ◽  
Respiratory Mechanics ◽  
Healthy Adult ◽  
Breathing Frequency ◽  
Healthy Male ◽  
Pulmonary Flow ◽  
Healthy Adult Male ◽  
Residual Capacity ◽  
Controlled Exposure

Eleven healthy, adult, male volunteers were exposed on separate occasions to average levels of sulfur dioxide of 1, 5, and 13 ppm. The subjects were seated in a body plethysmograph, breathing spontaneously by mouth while measurements of respiratory mechanics were made with an esophageal catheter. Exposures lasted 10–30 min and, for each subject, were spaced at least 1 month apart. With one exception the group showed no significant increase in pulmonary flow resistance at the lowest concentration of gas. At both 5 and 13 ppm, flow resistance was elevated, the change being greater at 13 ppm. The change occurred within 1 min of exposure, increased after 5 min but, on the average, showed no further change after 10 min. Four subjects were exposed to 5 or 13 ppm of SO2 for 30 min without exhibiting increases in flow resistance beyond the 1st 10 min. There were no consistent changes in pulmonary compliance, tidal volume, breathing frequency, or pulse rate. The functional residual capacity increased slightly during exposure to 13 ppm. Note: (With the Technical Assistance of Eleanor Root) Submitted on May 24, 1961

Effect of mechanical loading on breathing patterns in women

1984 ◽  
Vol 56 (1) ◽  
pp. 175-181 ◽  
Author(s):  
K. Axen ◽  
F. Haas ◽  
D. Gaudino ◽  
S. S. Haas
Keyword(s):  
Tidal Volume ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Men And Women ◽  
Ventilatory Responses ◽  
Frequency Responses ◽  
Group Response ◽  
Resistive Loading ◽  
Elastic Loading ◽  
Resistive Loads

First-breath ventilatory responses to graded inspiratory elastic and resistive loads were obtained from 80 women unfamiliar with respiratory experimentation. For each load 1) responses from different subjects ranged from a weak tidal volume defense coupled with an increased breathing frequency to a strong tidal volume defense coupled with a decreased frequency; 2) strong tidal volume defenders employed longer inspirations than did weak tidal volume defenders; and 3) individual respiratory frequency responses were mediated by changes in inspiratory and/or expiratory timing. Thus the group response was qualitatively the same as that reported for 80 men. Quantitatively, however, mean inspiratory airflow responses of women exceeded those of men by an amount attributable to women's higher intrinsic respiratory elastance. Tidal volume responses, on the other hand, did not differ significantly, suggesting that men and women produce different neural adjustments to loads. In support of this hypothesis, analysis of respiratory timing responses revealed that 1) men actively prolonged inspiration more than women during resistive loading; and 2) women actively shortened inspiration more than men during elastic loading. These findings indicate that the load-compensating behavior exhibited by men and women is similar but not identical.

Studies of calcium-45 desaturation from kidney slices in flow-through chambers

1978 ◽  
Vol 234 (1) ◽  
pp. R34-R38
Author(s):  
T. Uchikawa ◽  
A. B. Borle
Keyword(s):  
Kinetic Parameters ◽  
Rat Kidney ◽  
Kidney Cells ◽  
Tissue Slices ◽  
Kidney Slices ◽  
System A ◽  
Order Of Magnitude ◽  
Exponential Equations ◽  
Flow Through ◽  
Best Fit

This paper describes a method to measure calcium fluxes and calcium exchangeable pools in tissue slices by continuous perifusion in flow-through chambers. 45Ca desaturation from rat kidney slices can be analyzed as in an open three-compartment catenary system. A set of equations is given to calculate all the relevant kinetic parameters from the triple exponential equations which best fit the desaturation curves. The results show that the kinetic parameters obtained in kidney slices by this new method are in the same order of magnitude as those previously observed in cultured monkey kidney cells.

Effects of expiratory loading on respiration in humans

1980 ◽  
Vol 49 (4) ◽  
pp. 601-608 ◽  
Author(s):  
B. Gothe ◽  
N. S. Cherniack
Keyword(s):  
Muscle Activity ◽  
Healthy Subjects ◽  
Respiratory Muscle ◽  
Resistive Load ◽  
Similar Magnitude ◽  
Occlusion Pressure ◽  
Ventilatory Responses ◽  
Residual Capacity ◽  
Resistive Loads ◽  
The Difference

We examined the effects of expiratory resistive loads of 10 and 18 cmH2O.l-1.s in healthy subjects on ventilation and occlusion pressure responses to CO2, respiratory muscle electromyogram, pattern of breathing, and thoracoabdominal movements. In addition, we compared ventilation and occlusion pressure responses to CO2 breathing elicited by breathing through an inspiratory resistive load of 10 cmH2O.l-1.s to those produced by an expiratory load of similar magnitude. Both inspiratory and expiratory loads decreased ventilatory responses to CO2 and increased the tidal volume achieved at any given level of ventilation. Depression of ventilatory responses to Co2 was greater with the larger than with the smaller expiratory load, but the decrease was in proportion to the difference in the severity of the loads. Occlusion pressure responses were increased significantly by the inspiratory resistive load but not by the smaller expiratory load. However, occlusion pressure responses to CO2 were significantly larger with the greater expiratory load than control. Increase in occlusion pressure observed could not be explained by changes in functional residual capacity or chemical drive. The larger expiratory load also produced significant increases in electrical activity measured during both inspiration and expiration. These results suggest that sufficiently severe impediments to breathing, even when they are exclusively expiratory, can enhance inspiratory muscle activity in conscious humans.

Breathlessness and respiratory mechanics during reflex or voluntary hyperventilation in patients with chronic airflow limitation

1987 ◽  
Vol 73 (3) ◽  
pp. 311-318 ◽  
Author(s):  
S. Freedman ◽  
R. Lane ◽  
A. Guz
Keyword(s):  
Visual Analogue Scale ◽  
Analogue Scale ◽  
Breathing Pattern ◽  
Respiratory Mechanics ◽  
Airflow Limitation ◽  
Breathing Patterns ◽  
Voluntary Hyperventilation ◽  
Mechanics Of Breathing ◽  
Central Processing ◽  
Mechanical Variable

1. Six patients with chronic airflow limitation rebreathed CO2. Subsequently they voluntarily copied their stimulated breathing pattern while normocapnia was maintained. On a separate occasion four of these patients performed progressively increasing exercise and later copied these breathing patterns. 2. During all experiments flow, ventilation and pleural pressures were recorded. In addition, breathlessness was measured on a visual analogue scale every 30 s. 3. In these patients voluntary copying of either form of stimulated breathing resulted in diminished breathlessness and in some cases in complete abolition of the sensation, despite similar levels and patterns of ventilation in the two situations. 4. No systematic or consistent differences in the mechanics of breathing between stimulated and voluntarily copied breathing were found. 5. There was no correlation found between breathlessness score and any mechanical variable measured. 6. These results show that despite similarity in mechanics between stimulated and voluntary hyperventilation, the sensation of breathlessness is much diminished during the latter in these patients. This suggests that the sensation of breathlessness is more dependent upon the awareness of central processing than upon input from peripheral mechanoreceptors.

scholarly journals Stabilizing immature breathing patterns of preterm infants using stochastic mechanosensory stimulation

2009 ◽  
Vol 107 (4) ◽  
pp. 1017-1027 ◽  
Author(s):  
Elisabeth Bloch-Salisbury ◽  
Premananda Indic ◽  
Frank Bednarek ◽  
David Paydarfar
Keyword(s):  
Preterm Infants ◽  
Respiratory Control ◽  
Behavioral State ◽  
Mean Square ◽  
Breathing Patterns ◽  
Nonlinear Properties ◽  
Improved Stability ◽  
Postconceptional Age ◽  
The Stability ◽  
Large Improvement

Breathing patterns in preterm infants consist of highly variable interbreath intervals (IBIs) that might originate from nonlinear properties of the respiratory oscillator and its input-output responses to peripheral and central signals. Here, we explore a property of nonlinear control, the potential for large improvement in the stability of breathing using low-level exogenous stochastic stimulation. Stimulation was administered to 10 preterm infants (postconceptional age: mean 33.3 wk, SD 1.7) using a mattress with embedded actuators that delivered small stochastic displacements (0.021 mm root mean square, 0.090 mm maximum, 30–60 Hz); this stimulus was subthreshold for causing arousal from sleep to wakefulness or other detectable changes in the behavioral state evaluated with polysomnography. We used a test-retest protocol with multiple 10-min intervals of stimulation, each paired with 10-min intervals of no stimulation. Stimulation induced an ∼50% reduction ( P = 0.003) in the variance of IBIs and an ∼50% reduction ( P = 0.002) in the incidence of IBIs > 5 s. The improved stability of eupneic breathing was associated with an ∼65% reduction ( P = 0.04) in the duration of O2 desaturation. Our findings suggest that nonlinear properties of the immature respiratory control system can be harnessed using afferent stimuli to stabilize eupneic breathing, thereby potentially reducing the incidence of apnea and hypoxia.

scholarly journals Arterial blood sampling in male CD-1 and C57BL/6J mice with 1% isoflurane is similar to awake mice

2018 ◽  
Vol 125 (6) ◽  
pp. 1749-1759 ◽  
Author(s):  
Ashley M. Loeven ◽  
Candace N. Receno ◽  
Caitlin M. Cunningham ◽  
Lara R. DeRuisseau
Keyword(s):  
Cardiovascular Responses ◽  
Blood Chemistry ◽  
Blood Sampling ◽  
Optimal Time ◽  
Mouse Strains ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Suitable Alternative ◽  
Arterial Blood Sampling ◽  
Arterial Blood

Isoflurane (ISO) is a commonly used anesthetic that offers rapid recovery for laboratory animal research. Initial studies indicated no difference in arterial Pco2 ([Formula: see text]) or pH between conscious (NO ISO) and 1% ISO-exposed CD-1 mice. Our laboratory investigated whether arterial blood sampling with 1% ISO is a suitable alternative to NO ISO sampling for monitoring ventilation in a commonly studied mouse strain. We hypothesized similar blood chemistry, breathing patterns, and cardiovascular responses with NO ISO and 1% ISO. C57BL/6J mice underwent unrestrained barometric plethysmography to quantify the pattern of breathing. Mice exposed to hypoxic and hypercapnic gas under 1% ISO displayed blunted responses; with air, there were no breathing differences. Blood pressure and heart rate were not different between NO ISO and 1% ISO-exposed mice breathing air. Oxygen saturation was not different between groups receiving 2% ISO, 1% ISO, or air. Breathing frequency stabilized at ~11 min of 1% ISO following 2% ISO exposure, suggesting that 11 min is the optimal time for a sample in C57BL/6J mice. Blood samples at 1% ISO and NO ISO revealed no differences in blood pH and [Formula: see text] in C57BL/6J mice. Overall, this method reveals similar arterial blood sampling values in awake and 1% ISO CD-1 and C57BL/6J mice exposed to air. Although this protocol may be appropriate in other mouse strains when a conscious sample is not feasible, caution is warranted first to identify breathing frequency responses at 1% ISO to tailor the protocol. NEW & NOTEWORTHY Conscious arterial blood sampling is influenced by extraneous factors and is a challenging method due to the small size of mice. Through a series of experiments, we show that arterial blood sampling with 1% isoflurane (ISO) is an alternative to awake sampling in C57BL/6J and CD-1 male mice breathing air. Monitoring breathing frequency during 1% ISO is important to the protocol and should be closely followed to confirm adequate recovery after the catheter implantation.

Inspiratory resistive load detection in conscious dogs

1991 ◽  
Vol 70 (3) ◽  
pp. 1284-1289 ◽  
Author(s):  
P. W. Davenport ◽  
D. J. Dalziel ◽  
B. Webb ◽  
J. R. Bellah ◽  
C. J. Vierck
Keyword(s):  
Training Stimulus ◽  
Detection Threshold ◽  
Resistive Load ◽  
Initial Training ◽  
Breathing Patterns ◽  
Physiological Mechanisms ◽  
Mechanical Loads ◽  
Load Detection ◽  
Resistive Loads ◽  
Tracheal Stoma

The physiological mechanisms mediating the detection of mechanical loads are unknown. This is, in part, due to the lack of an animal model of load detection that could be used to investigate specific sensory systems. We used American Foxhounds with tracheal stomata to behaviorally condition the detection of inspiratory occlusion and graded resistive loads. The resistive loads were presented with a loading manifold connected to the inspiratory port of a non-rebreathing valve. The dogs signaled detection of the load by lifting their front paw off a lever. Inspiratory occlusion was used as the initial training stimulus, and the dogs could reliably respond within the first or second inspiratory effort to 100% of the occlusion presentations after 13 trials. Graded resistances that spanned the 50% detection threshold were then presented. The detection threshold resistances (delta R50) were 0.96 and 1.70 cmH2O.l-1.s. Ratios of delta R50 to background resistance were 0.15 and 0.30. The near-threshold resistive loads did not significantly change expired PCO2 or breathing patterns. These results demonstrate that dogs can be conditioned to reliably and specifically signal the detection of graded inspiratory mechanical loads. Inspiration through the tracheal stoma excludes afferents in the upper extrathoracic trachea, larynx, pharynx, nasal passages, and mouth from mediating load detection in these dogs. It is unknown which remaining afferents (vagal or respiratory muscle) are responsible for load detection.

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