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.

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.

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.

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.

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.

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.

scholarly journals Accuracy of noninvasive estimates of respiratory muscle effort during spontaneous breathing in restrictive diseases

2003 ◽  
Vol 95 (4) ◽  
pp. 1542-1549 ◽  
Author(s):  
Francisco García-Río ◽  
José M. Pino ◽  
Angeles Ruiz ◽  
Salvador Díaz ◽  
Concepción Prados ◽  
...  
Keyword(s):  
Spontaneous Breathing ◽  
Respiratory Muscle ◽  
Usual Interstitial Pneumonia ◽  
Neuromuscular Diseases ◽  
Normal Subjects ◽  
Esophageal Pressure ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Transdiaphragmatic Pressure ◽  
Inspiratory Muscles

Mean inspiratory pressure (Pi), estimated from the occlusion pressure at the mouth and the inspiratory time, is useful as a noninvasive estimate of respiratory muscle effort during spontaneous breathing in normal subjects and patients with chronic obstructive pulmonary disease. The aim of this study was to compare the Pi with respect to mean esophageal pressure (Pes) in patients with restrictive disorders. Eleven healthy volunteers, 12 patients with chest wall disease, 14 patients with usual interstitial pneumonia, and 17 patients with neuromuscular diseases were studied. Pi, Pes, and mean transdiaphragmatic pressure were simultaneously measured. Tension-time indexes of diaphragm (TTdi) and inspiratory muscles (TTmu) were also determined. In neuromuscular patients, significant correlations were found between Pi and Pes, Pi and transdiaphragmatic pressure, and TTmu and TTdi. A moderate agreement between Pi and Pes and between TTmu and TTdi was found. No significant correlation between these parameters was found in the other patient groups. These findings suggest that Pi is a good surrogate for the invasive measurement of respiratory muscle effort during spontaneous breathing in neuromuscular patients.

Effect of resistive loads on pattern of respiratory muscle recruitment during exercise

1991 ◽  
Vol 71 (5) ◽  
pp. 1941-1948 ◽  
Author(s):  
M. Ramonatxo ◽  
J. Mercier ◽  
R. Cohendy ◽  
C. Prefaut
Keyword(s):  
Respiratory Muscle ◽  
Minute Ventilation ◽  
Abdominal Muscles ◽  
Resistive Load ◽  
Muscle Recruitment ◽  
O2 Uptake ◽  
Exercise Tests ◽  
Co2 Output ◽  
Resistive Loads ◽  
Mouth Occlusion Pressure

In healthy subjects, we compared the effects of an expiratory (ERL) and an inspiratory (IRL) resistive load (6 cmH2O.l-1.s) with no added resistive load on the pattern of respiratory muscle recruitment during exercise. Fifteen male subjects performed three exercise tests at 40% of maximum O2 uptake: 1) with no-added-resistive load (control), 2) with ERL, and 3) with IRL. In all subjects, we measured breathing pattern and mouth occlusion pressure (P0.1) from the 3rd min of exercise, in 10 subjects O2 uptake (VO2), CO2 output (VCO2), and respiratory exchange ratio (R), and in 5 subjects we measured gastric (Pga), pleural (Ppl), and transdiaphragmatic (Pdi) pressures. Both ERL and IRL induced a high increase of P0.1 and a decrease of minute ventilation. ERL induced a prolongation of expiratory time with a reduction of inspiratory time (TI), mean expiratory flow, and ratio of inspiratory to total time of the respiratory cycle (TI/TT). IRL induced a prolongation of TI with a decrease of mean inspiratory flow and an increase of tidal volume and TI/TT. With ERL, in two subjects, Pga increased and Ppl decreased more during inspiration than during control suggesting that the diaphragm was the most active muscle. In one subject, the increases of Ppl and Pga were weak; thus Pdi increased very little. In the two other subjects, Ppl decreased more during inspiration but Pga also decreased, leading to a decrease of Pdi. This suggests a recruitment of abdominal muscles during expiration and of accessory and intercostal muscles during inspiration. With IRL, in all subjects, Ppl again decreased more, Pga began to decrease until 40% of TI and then increased.(ABSTRACT TRUNCATED AT 250 WORDS)

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