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.

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.

Resistive Load Detection during Passive Ventilation

1980 ◽  
Vol 59 (6) ◽  
pp. 493-495 ◽  
Author(s):  
K. J. Killian ◽  
C. K. Mahutte ◽  
E. J. M. Campbell
Keyword(s):  
Muscle Contraction ◽  
Spontaneous Breathing ◽  
Respiratory Muscle ◽  
Essential Role ◽  
Normal Subjects ◽  
Assisted Ventilation ◽  
Resistive Load ◽  
Load Detection ◽  
Resistive Loads

1. By using standard psychophysical techniques resistive load detection was estimated in five normal subjects during spontaneous breathing and during passive ventilation in a Drinker respirator. 2. During assisted ventilation a gross deterioration in resistive load detection occurred. 3. The findings imply that active respiratory muscle contraction plays an essential role in the detection of added resistive loads.

Superior laryngeal nerve blockade and inspiratory resistive load detection in normal subjects

1995 ◽  
Vol 79 (5) ◽  
pp. 1567-1570 ◽  
Author(s):  
M. F. Fitzpatrick ◽  
T. Zintel ◽  
M. Stockwell ◽  
J. Mink ◽  
C. G. Gallagher
Keyword(s):  
Superior Laryngeal Nerve ◽  
Normal Subjects ◽  
Laryngeal Nerve ◽  
Controlled Study ◽  
Resistive Load ◽  
Detection Thresholds ◽  
Nerve Blockade ◽  
Load Detection ◽  
Significant Difference ◽  
Resistive Loads

The site for detection of added inspiratory resistive loads is unknown, but recent evidence suggests that the airways may play an important role. The aim of this study was to discern whether the larynx has an important independent role in conscious detection of added inspiratory resistive loads. A randomized double-blind placebo-controlled study of the effect of superior laryngeal nerve blockade on inspiratory resistive load-detection threshold was carried out in 12 normal subjects (7 women; mean age 27.5 yr; range 18–45 yr). Baseline (preinjection) detection thresholds were similar on the lidocaine [0.58 +/- 0.16 (SE) cmH2O.l-1.s] and saline (0.53 +/- 0.12 cmH2O.l-1.s; P = 0.28) days. There was no significant difference in load-detection thresholds after injection between lidocaine (0.60 +/- 0.15 cmH2O.l-1.s) and saline (0.55 +/- 0.10 cmH2O.l-1.s; P = 0.68). Thus, the larynx does not appear to be an important independent airway site for conscious inspiratory resistive load detection.

A Signal Detection Theory Analysis of the Effect of Chest Cage Restriction upon the Detection of Inspiratory Resistive Loads

1983 ◽  
Vol 64 (4) ◽  
pp. 417-421
Author(s):  
P. G. Narbed ◽  
D. Marcer ◽  
J. B. L. Howell ◽  
E. Spencer
Keyword(s):  
Signal Detection ◽  
Signal Detection Theory ◽  
Normal Subjects ◽  
Detection Theory ◽  
Detection Sensitivity ◽  
Resistive Load ◽  
Load Detection ◽  
Resistive Loads ◽  
Willingness To Report ◽  
And Control

1. By the use of Signal Detection Theory techniques, resistive load detection sensitivity was estimated in six normal subjects, and compared with detection when the chest cage was strapped in the position of full expiration. 2. With chest cage restriction there was both a decrease in detection sensitivity and an increase in the willingness to report the presence of an added load to breathing. 3. This suggests that the similarity of detection in chest clamping and control previously reported was due partly to increased detection bias with chest clamping. 4. These results have implications concerning the dependence of detection on afferent information from the chest wall.

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.

Respiratory and Laryngeal Function During Whispering

1991 ◽  
Vol 34 (4) ◽  
pp. 761-767 ◽  
Author(s):  
Elaine T. Stathopoulos ◽  
Jeannette D. Hoit ◽  
Thomas J. Hixon ◽  
Peter J. Watson ◽  
Nancy Pearl Solomon
Keyword(s):  
Young Adults ◽  
Chest Wall ◽  
Voice Disorders ◽  
Normal Subjects ◽  
High Rate ◽  
Lung Volumes ◽  
Laryngeal Function ◽  
Tracheal Pressure ◽  
Lower Lung ◽  
Resistive Loads

Established procedures for making chest wall kinematic observations (Hoit & Hixon, 1987) and pressure-flow observations (Smitheran & Hixon, 1981) were used to study respiratory and laryngeal function during whispering and speaking in 10 healthy young adults. Results indicate that whispering involves generally lower lung volumes, lower tracheal pressures, higher translaryngeal flows, lower laryngeal airway resistances, and fewer syllables per breath group when compared to speaking. The use of lower lung volumes during whispering than speaking may reflect a means of achieving different tracheal pressure targets. Reductions in the number of syllables produced per breath group may be an adjustment to the high rate of air expenditure accompanying whispering compared to speaking. Performance of the normal subjects studied in this investigation does not resemble that of individuals with speech and voice disorders characterized by low resistive loads.

Steady-state response of quadriplegic subjects to inspiratory resistive load

1986 ◽  
Vol 60 (5) ◽  
pp. 1482-1492 ◽  
Author(s):  
V. Im Hof ◽  
H. Dubo ◽  
V. Daniels ◽  
M. Younes
Keyword(s):  
Steady State ◽  
Chest Wall ◽  
Muscle Spindles ◽  
Normal Subjects ◽  
Afferent Feedback ◽  
Resistive Load ◽  
State Response ◽  
The Face ◽  
Inspiratory Resistance

Normal subjects preserve tidal volume (VT) in the face of added inspiratory resistance by increasing maximal amplitude and duration of the rising phase of respiratory driving pressure (DP) and by changing the shape of this phase to one that is more concave to the time axis. To explore the possible role of chest wall afferents in mediating these responses, we determined averaged DP in eight quadriplegic subjects during steady-state unloaded breathing and while breathing through an inspiratory resistance (8.5 cmH2O X 1(-1) X s). As with normal subjects, quadriplegics preserved VT (loaded VT = 106% control) by utilizing all three mechanisms. However, prolongation of the inspiratory duration derived from the DP waveform (+22% vs. +42%) and shape response were significantly less in the quadriplegic subjects. Shape response was completely absent in subjects with C4 lesions. The results provide strong evidence that respiratory muscle spindles are responsible for shape response and that changes in afferent feedback from the chest wall play an important role in mediating inspiratory prolongation.

Effect of ventilatory drive on the perceived magnitude of added loads to breathing

1982 ◽  
Vol 53 (4) ◽  
pp. 901-907 ◽  
Author(s):  
J. G. Burdon ◽  
K. J. Killian ◽  
E. J. Campbell
Keyword(s):  
Power Function ◽  
Muscle Force ◽  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Inspiratory Pressure ◽  
Resistive Load ◽  
Sensory Magnitude ◽  
Magnitude Scaling ◽  
Ventilatory Drive ◽  
Resistive Loads

Using open-magnitude scaling we studied the importance of ventilatory drive on the perceived magnitude of respiratory loads by applying a range of externally added resistances (2.1–77.1 cmH2O X l-1 X s) to normal subjects at rest and at three increasing levels of ventilatory drive induced by exercise, CO2-stimulated breathing, and hypoxia. Under all conditions studied the perceived magnitude of the added loads increased with the magnitude of the resistive load and as the underlying level of ventilatory drive increased. When the results were expressed in terms of peak inspiratory pressure, the perceived magnitude was related to the magnitude of the peak inspiratory pressure by a power function (mean r = 0.97). These results suggest that the perceived magnitude of added resistive loads increased with increasing ventilatory drive, in such a manner that the increase in sensory magnitude is proportional to the increase in the inspiratory muscle force developed and suggests that something dependent on this force mediates the sensation.

scholarly journals Repeatability of the Evaluation of Perception of Dyspnea in Normal Subjects Assessed Through Inspiratory Resistive Loads

2014 ◽  
Vol 8 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Andréia K Fernandes ◽  
Bruna Ziegler ◽  
Glauco L Konzen ◽  
Paulo R.S Sanches ◽  
André F Müller ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Cross Sectional Study ◽  
Resistive Load ◽  
Cross Sectional ◽  
Intra Class Correlation ◽  
Significant Difference ◽  
Loading System ◽  
Resistive Loads ◽  
The Brain ◽  
Intra Class Correlation Coefficient

Purpose: Study the repeatability of the evaluation of the perception of dyspnea using an inspiratory resistive loading system in healthy subjects. Methods: We designed a cross sectional study conducted in individuals aged 18 years and older. Perception of dyspnea was assessed using an inspiratory resistive load system. Dyspnea was assessed during ventilation at rest and at increasing resistive loads (0.6, 6.7, 15, 25, 46.7, 67, 78 and returning to 0.6 cm H2O/L/s). After breathing in at each level of resistive load for two minutes, the subject rated the dyspnea using the Borg scale. Subjects were tested twice (intervals from 2 to 7 days). Results: Testing included 16 Caucasian individuals (8 male and 8 female, mean age: 36 years). The median scores for dyspnea rating in the first test were 0 at resting ventilation and 0, 2, 3, 4, 5, 7, 7 and 1 point, respectively, with increasing loads. The median scores in the second test were 0 at resting and 0, 0, 2, 2, 3, 4, 4 and 0.5 points, respectively. The intra-class correlation coefficient was 0.57, 0.80, 0.74, 0.80, 0.83, 0.86, 0.91, and 0.92 for each resistive load, respectively. In a generalized linear model analysis, there was a statistically significant difference between the levels of resistive loads (p<0.001) and between tests (p=0.003). Dyspnea scores were significantly lower in the second test. Conclusion: The agreement between the two tests of the perception of dyspnea was only moderate and dyspnea scores were lower in the second test. These findings suggest a learning effect or an effect that could be at least partly attributed to desensitization of dyspnea sensation in the brain.

Effect of ethanol and naloxone on control of ventilation and load perception

1983 ◽  
Vol 55 (3) ◽  
pp. 929-934 ◽  
Author(s):  
T. M. Michiels ◽  
R. W. Light ◽  
C. K. Mahutte
Keyword(s):  
Normal Subjects ◽  
Ethanol Ingestion ◽  
Resistive Load ◽  
Load Compensation ◽  
Ventilatory Responses ◽  
Resistive Loading ◽  
Resistive Loads ◽  
Mouth Occlusion Pressure ◽  
Load Perception ◽  
Respiratory Depressant

The respiratory depressant effects of ethanol and their potential reversibility by naloxone were studied in 10 normal subjects. Ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia without and with an inspiratory resistive load (13 cmH2O X 1(-1) X S) were measured. The resistive load detected with 50% probability (delta R50) and the exponent (n) in Stevens' psychophysical law for magnitude estimation of resistive loads were studied using standard psychophysical techniques. Each of these studies was performed before ethanol ingestion, after ethanol ingestion (1.5 ml/kg, by mouth), and then again after naloxone (0.8 mg iv). Ethanol increased delta R50 (P less than 0.05) and decreased n (P less than 0.05). Naloxone caused no further change in these parameters. The load compensation (Lc), defined as the ratio of loaded to unloaded response slopes, was not significantly changed after ethanol and naloxone. No correlation was found between the Lc and delta R50 or n. The ventilatory and P0.1 responses to hypercapnia and hypoxia with and without inspiratory resistive loading decreased after ethanol (P less than 0.05, hypercapnia; NS, hypoxia). After naloxone the hypercapnic ventilatory responses increased (P less than 0.05). This suggests that the respiratory depressant effects of ethanol may be mediated via endorphins.

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