Detection Latency of Added Loads to Breathing

1982 ◽  
Vol 63 (1) ◽  
pp. 11-15 ◽  
Author(s):  
J. G. W. Burdon ◽  
K. J. Killian ◽  
E. J. M. Campbell
Keyword(s):  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Reciprocal Relationship ◽  
Respiratory Cycle ◽  
Curvilinear Relationship ◽  
Similar Relationship ◽  
Detection Latency ◽  
Mechanical Information ◽  
Resistive Loads ◽  
Comparable Magnitude

1. Detection latency of a range of added elastic (0·95–4·50 kPa/l) and resistive (0·73–3·29 kPa l−1 s) loads to breathing were measured in five normal subjects. Detection latency was defined as the time from the onset of the breath to detection of the load. 2. Detection latency followed a curvilinear relationship when plotted as a function of the magnitude of the added loads. A similar relationship was found with both elastic and resistive loads although detection latencies to added elastances were longer than for added resistances. 3. When the added load was expressed in terms of comparable magnitude (peak inspiratory pressure) detection latencies for added elastances were found to be consistently longer than for added resistive loads. 4. These studies show that the detection latency to added inspiratory loads follows a reciprocal relationship, that detection latencies for elastic and resistive loads are clearly different and suggest that these loads are detected during the respiratory cycle at a time when the mechanical information regarding muscular pressure is greatest.

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.

Sustained isocapnic hypoxia suppresses the perception of the magnitude of inspiratory resistive loads

2000 ◽  
Vol 89 (1) ◽  
pp. 47-55 ◽  
Author(s):  
R. S. Orr ◽  
A. S. Jordan ◽  
P. Catcheside ◽  
N. A. Saunders ◽  
R. D. McEvoy
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Inspiratory Pressure ◽  
Respiratory Resistance ◽  
Stimulus Magnitude ◽  
Mean Values ◽  
Central Nervous System Depressant ◽  
Resistive Loads

The sensation of increased respiratory resistance or effort is likely to be important for the initiation of alerting or arousal responses, particularly in sleep. Hypoxia, through its central nervous system-depressant effects, may decrease the perceived magnitude of respiratory loads. To examine this, we measured the effect of isocapnic hypoxia on the ability of 10 normal, awake males (mean age = 24.0 ± 1.8 yr) to magnitude-scale five externally applied inspiratory resistive loads (mean values from 7.5 to 54.4 cmH2O · l−1 · s). Each subject scaled the loads during 37 min of isocapnic hypoxia (inspired O2 fraction = 0.09, arterial O2 saturation of ∼80%) and during 37 min of normoxia, using the method of open magnitude numerical scaling. Results were normalized by modulus equalization to allow between-subject comparisons. With the use of peak inspiratory pressure (PIP) as the measure of load stimulus magnitude, the perception of load magnitude (Ψ) increased linearly with load and, averaged for all loaded breaths, was significantly lower during hypoxia than during normoxia (20.1 ± 0.9 and 23.9 ± 1.3 arbitrary units, respectively; P = 0.048). Ψ declined with time during hypoxia ( P = 0.007) but not during normoxia ( P= 0.361). Our result is remarkable because PIP was higher at all times during hypoxia than during normoxia, and previous studies have shown that an elevation in PIP results in increased Ψ. We conclude that sustained isocapnic hypoxia causes a progressive suppression of the perception of the magnitude of inspiratory resistive loads in normal subjects and could, therefore, impair alerting or arousal responses to respiratory loading.

Inspiratory muscle forces and endurance in maximum resistive loading

1985 ◽  
Vol 58 (5) ◽  
pp. 1608-1615 ◽  
Author(s):  
G. L. Jones ◽  
K. J. Killian ◽  
E. Summers ◽  
N. L. Jones
Keyword(s):  
Peak Inspiratory Pressure ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Inspiratory Pressure ◽  
Endurance Capacity ◽  
Breathing Patterns ◽  
O2 Uptake ◽  
Maximum Resistance ◽  
Inspiratory Muscles ◽  
Resistive Loads

The ability of the respiratory muscles to sustain ventilation against increasing inspiratory resistive loads was measured in 10 normal subjects. All subjects reached a maximum rating of perceived respiratory effort and at maximum resistance showed signs of respiratory failure (CO2 retention, O2 desaturation, and rib cage and abdominal paradox). The maximum resistance achieved varied widely (range 73–660 cmH2O X l-1 X s). The increase in O2 uptake (delta Vo2) associated with loading was linearly related to the integrated mouth pressure (IMP): delta Vo2 = 0.028 X IMP + 19 ml/min (r = 0.88, P less than 0.001). Maximum delta Vo2 was 142 ml/min +/- SD 68 ml/min. There were significant (P less than 0.05) relationships between the maximum voluntary inspiratory pressure against an occluded airway (MIP) and both maximum IMP (r = 0.80) and maximum delta Vo2 (r = 0.76). In five subjects, three imposed breathing patterns were used to examine the effect of different patterns of respiratory muscle force deployment. Increasing inspiratory duration (TI) from 1.5 to 3.0 and 6.0 s, at the same frequency of breathing (5.5 breaths/min) reduced peak inspiratory pressure and increased the maximum resistance tolerated (190, 269, and 366 cmH2O X l-1 X s, respectively) and maximum IMP (2043, 2473, and 2913 cmH2O X s X min-1, but the effect on maximum delta Vo2 was less consistent (166, 237, and 180 ml/min). The ventilatory endurance capacity and the maximum O2 uptake of the respiratory muscles are related to the strength of the inspiratory muscles, but are also modified through the pattern of force deployment.

Ventilatory and occlusion pressure responses to helium breathing

1983 ◽  
Vol 54 (6) ◽  
pp. 1525-1531 ◽  
Author(s):  
E. L. DeWeese ◽  
T. Y. Sullivan ◽  
P. L. Yu
Keyword(s):  
Breathing Circuit ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Mouth Pressure ◽  
Partial Pressure Of Co2 ◽  
Lung Resistance ◽  
Balloon Technique ◽  
Resistive Loads ◽  
End Tidal ◽  
Airway Tone

To characterize the ventilatory response to resistive unloading, we studied the effect of breathing 79.1% helium-20.9% oxygen (He-O2) on ventilation and on mouth pressure measured during the first 100 ms of an occluded inspiration (P100) in normal subjects at rest. The breathing circuit was designed so that external resistive loads during both He-O2 and air breathing were similar. Lung resistance, measured in three subjects with an esophageal balloon technique, was reduced by 23 +/- 8% when breathing He-O2. Minute ventilation, tidal volume, respiratory frequency, end-tidal partial pressure of CO2, inspiratory and expiratory durations, and mean inspiratory flow were not significantly different when air was replaced by He-O2. P100, however, was significantly less during He-O2 breathing. We conclude that internal resistive unloading by He-O2 breathing reduces the neuromuscular output required to maintain constant ventilation. Unlike studies involving inhaled bronchodilators, this technique affords a method by which unloading can be examined independent of changes in airway tone.

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.

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 expiratory loading on glottic dimensions in humans

1985 ◽  
Vol 58 (2) ◽  
pp. 605-611 ◽  
Author(s):  
T. P. Brancatisano ◽  
D. S. Dodd ◽  
P. W. Collett ◽  
L. A. Engel
Keyword(s):  
Inverse Relationship ◽  
Time Course ◽  
Normal Subjects ◽  
Positive End Expiratory Pressure ◽  
Expiratory Resistance ◽  
Mouth Pressure ◽  
Internal Impedance ◽  
Resistive Loads ◽  
Increased Activity ◽  
Medullary Neurons

We examined the effects of external mechanical loading on glottic dimensions in 13 normal subjects. When flow-resistive loads of 7, 27, and 48 cmH2O X l-1 X s, measured at 0.2 l/s, were applied during expiration, glottic width at the mid-tidal volume point in expiration (dge) was 2.3 +/- 12, 37.9 +/- 7.5, and 38.3 +/- 8.9% (means +/- SE) less than the control dge, respectively. Simultaneously, mouth pressure (Pm) increased by 2.5 +/- 4, 3.0 +/- 0.4, and 4.6 +/- 0.6 cmH2O, respectively. When subjects were switched from a resistance to a positive end-expiratory pressure at comparable values of Pm, both dge and expiratory flow returned to control values, whereas the level of hyperinflation remained constant. Glottic width during inspiration (unloaded) did not change on any of the resistive loads. There was a slight inverse relationship between the ratio of expiratory to inspiratory glottic width and the ratio of expiratory to inspiratory duration. Our results show noncompensatory glottic narrowing when subjects breathe against an expiratory resistance and suggest that the glottic dimensions are influenced by the time course of lung emptying during expiration. We speculate that the glottic constriction is related to the increased activity of expiratory medullary neurons during loaded expiration and, by increasing the internal impedance of the respiratory system, may have a stabilizing function.

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.

Effect of background loads on the perception of added loads to breathing

1983 ◽  
Vol 54 (5) ◽  
pp. 1222-1228 ◽  
Author(s):  
J. G. Burdon ◽  
K. J. Killian ◽  
D. G. Stubbing ◽  
E. J. Campbell
Keyword(s):  
Control Experiment ◽  
Statistical Significance ◽  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Elastic Load ◽  
Magnitude Scaling ◽  
Significant Difference ◽  
Loaded Breathing ◽  
Function Relationship ◽  
Background Load

Using open-magnitude scaling, we compared the perceived magnitude of externally added resistive and elastic loads to breathing in normal subjects with that perceived when the background load (i.e., the minimum load of the circuit) was increased by the addition of either resistive or elastic loads of increasing magnitude. The study was carried out over four experimental sessions. After a control experiment (no added background load), the background load was increased by the addition of either a resistive or an elastic load for a duration of 3 min. The perceived magnitude of a further series of loads, proportionately increased, was then ascertained. This sequence was then repeated after a further increase in background. The results showed that the perceived magnitude of the load was closely related [mean r = 0.96 +/- 0.01 (SE)] to the magnitude of the physical stimulus expressed as the peak inspiratory pressure by a power function relationship in keeping with Stevens' law. After the increases in background resistance or elastance, there were no significant differences in either exponents or intercepts compared with basal conditions. There was no significant difference in the perceived magnitude of the loads after adaptation. At the smallest load, the perceived magnitude was less than expected from the control experiment. However, this reduction did not reach statistical significance. In the special senses, moderate-to-large stimuli show little change after adaptation, whereas small stimuli are reduced. Although not conclusive, we suggest that the relationship is similar with loaded breathing.

Coordination of respiration and swallowing: effect of bolus volume in normal adults

1992 ◽  
Vol 263 (3) ◽  
pp. R624-R630 ◽  
Author(s):  
H. G. Preiksaitis ◽  
S. Mayrand ◽  
K. Robins ◽  
N. E. Diamant
Keyword(s):  
Normal Population ◽  
Normal Subjects ◽  
Respiratory Cycle ◽  
Respiratory Pattern ◽  
Nasal Airflow ◽  
Bolus Volume ◽  
Swallow Apnea ◽  
Normal Adults

The coordination of swallowing and respiration, as measured by nasal airflow, and the effect of changes in the volume of the swallow bolus (0-20 ml) were investigated in 12 normal subjects. Both nonbolus and bolus swallows were usually preceded and followed by expiratory airflow. Swallows followed by inspiratory airflow accounted for 20% of nonbolus swallows but decreased further in frequency in the presence of a bolus. Swallowing was associated with an apneic period lasting 1.90 +/- 0.26 s for nonbolus swallows. Based on the apneic period response to bolus volume, the subjects were divided into two groups. The apneic period decreased by 60% in seven of the subjects regardless of bolus volume. The remaining five subjects gradually increased swallow apnea as bolus volume was increased. At larger bolus volumes, the latter group also exhibited an earlier onset of the swallow apnea and an increase in the number of swallows preceded by inspiration. The duration of the swallow-associated respiratory cycle was similarly prolonged by an increase in bolus volume in both groups. The results indicate that the respiratory pattern associated with swallowing is modulated by the volume of the swallow bolus. Within the normal population, at least two different patterns of response to bolus volume are identified.

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