Effect of inspiratory muscle fatigue on breathing pattern during inspiratory resistive loading

1991 ◽  
Vol 70 (4) ◽  
pp. 1627-1632 ◽  
Author(s):  
M. J. Mador ◽  
F. A. Acevedo
Keyword(s):  
Muscle Fatigue ◽  
Breathing Pattern ◽  
Inspiratory Muscle ◽  
Transdiaphragmatic Pressure ◽  
Inspiratory Muscles ◽  
Resistive Loading ◽  
Diaphragmatic Fatigue ◽  
Shallow Breathing ◽  
Resistive Loads ◽  
Inspiratory Muscle Fatigue

The purpose of this study was to determine whether induction of either inspiratory muscle fatigue (expt 1) or diaphragmatic fatigue (expt 2) would alter the breathing pattern response to large inspiratory resistive loads. In particular, we wondered whether induction of fatigue would result in rapid shallow breathing during inspiratory resistive loading. The breathing pattern during inspiratory resistive loading was measured for 5 min in the absence of fatigue (control) and immediately after induction of either inspiratory muscle fatigue or diaphragmatic fatigue. Data were separately analyzed for the 1st and 5th min of resistive loading to distinguish between immediate and sustained effects. Fatigue was achieved by having the subjects breathe against an inspiratory threshold load while generating a predetermined fraction of either the maximal mouth pressure or maximal transdiaphragmatic pressure until they could no longer reach the target pressure. Compared with control, there were no significant alterations in breathing pattern after induction of fatigue during either the 1st or 5th min of resistive loading, regardless of whether fatigue was induced in the majority of the inspiratory muscles or just in the diaphragm. We conclude that the development of inspiratory muscle fatigue does not alter the breathing pattern response to large inspiratory resistive loads.

Physiological Determinants of Inspiratory Effort Sensation during CO2 Rebreathing in Normal Subjects

1993 ◽  
Vol 85 (5) ◽  
pp. 637-642 ◽  
Author(s):  
J. E. Clague ◽  
J. Carter ◽  
M. G. Pearson ◽  
P. M. A. Calverley
Keyword(s):  
Partial Pressure ◽  
Muscle Fatigue ◽  
Breathing Pattern ◽  
Normal Subjects ◽  
Inspiratory Effort ◽  
Inspiratory Muscle ◽  
Time Index ◽  
Partial Pressure Of Co2 ◽  
Tension Time ◽  
Inspiratory Muscle Fatigue

1. The physiological basis of inspiratory effort sensation remains uncertain. Previous studies have suggested that pleural pressure, rather than inspiratory muscle fatigue, is the principal determinant of inspiratory effort sensation. However, only a limited range of inspiratory flows and breathing patterns have been examined. We suspected that inspiratory effort sensation was related to the inspiratory muscle tension-time index developed whatever the breathing pattern or load, and that this might explain the additional rise in sensation seen with hypercapnia. 2. To investigate this we measured hypercapnic re-breathing responses in seven normal subjects (six males, age range 21–38 years) with and without an inspiratory resistive load of 10 cm H2O. Pleural and transdiaphragmatic pressures, mouth occlusion pressure and breathing pattern were measured. Diaphragmatic and ribcage tension-time indices were calculated from these data. Inspiratory effort sensation was recorded using a Borg scale at 30s intervals during each rebreathing run. 3. Breathing pattern and inspiratory pressure partitioning were unrelated to changes in inspiratory effort sensation during hypercapnia. Tension-time indices reached pre-fatiguing levels during both free breathing and inspiratory resistive loading. 4. Stepwise multiple regression analysis using pooled mechanical, chemical and breathing pattern variables showed that pleural pressure was more closely related to inspiratory effort sensation than was transdiaphragmatic pressure. When converted to tension-time indices, ribcage tension-time index was the major determinant of inspiratory effort sensation during loaded rebreathing, but partial pressure of CO2 was an important independent variable, whereas during unloaded rebreathing partial pressure of CO2 was the most important determinant of inspiratory effort sensation. 5. These results suggest that the pattern of inspiratory pressure partitioning and inspiratory flow rate have little influence on inspiratory effort sensation during CO2 stimulated breathing. The close association between inspiratory effort sensation and ribcage tension-time index, an index of inspiratory muscle work, suggests that inspiratory effort sensation may forewarn of potential inspiratory muscle fatigue. Changes in PaCO2 have a small independent effect on respiratory perception.

Influence of global inspiratory muscle fatigue on breathing during exercise

1996 ◽  
Vol 80 (4) ◽  
pp. 1270-1278 ◽  
Author(s):  
P. Sliwinski ◽  
S. Yan ◽  
A. P. Gauthier ◽  
P. T. Macklem
Keyword(s):  
Tidal Volume ◽  
Muscle Fatigue ◽  
Minute Ventilation ◽  
Inspiratory Muscle ◽  
Abdominal Muscles ◽  
Maximal Power Output ◽  
Lung Inflation ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Inspiratory Muscle Fatigue

We evaluated the effect of global inspiratory muscle fatigue (GF) on respiratory muscle control during exercise at 30, 60, and 90% of maximal power output in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. Esophageal and gastric pressures, anteroposterior displacement of the rib cage and abdomen, breathing pattern, and perceived breathlessness were measured. Induction of GF had no effect on the ventilatory parameters during mild and moderate exercise. It altered, however, ventilatory response to heavy exercise by increasing breathing frequency and minute ventilation, with minor changes in tidal volume. This was accompanied by an increase in perceived breathlessness. GF significantly increased both the tonic and phasic activities of abdominal muscles that allowed 1) the diaphragm to maintain its function while developing less pressure, 2) the same tidal volume with lesser shortening of the rib cage inspiratory muscles, and 3) relaxation of the abdominal muscles to contribute to lung inflation. The increased work performed by the abdominal muscles may, however, lead to a reduction in their strength. GF may impair exercise performance in some healthy subjects that is probably not related to excessive breathlessness or other ventilatory factors. We conclude that the respiratory system is remarkably adaptable in maintaining ventilation during exercise even with impaired inspiratory muscle contractility.

Effect of global inspiratory muscle fatigue on ventilatory and respiratory muscle responses to CO2

1993 ◽  
Vol 75 (3) ◽  
pp. 1371-1377 ◽  
Author(s):  
S. Yan ◽  
P. Sliwinski ◽  
A. P. Gauthier ◽  
I. Lichros ◽  
S. Zakynthinos ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Respiratory Muscle ◽  
Minute Ventilation ◽  
Inspiratory Muscle ◽  
Response Curves ◽  
Initial Portion ◽  
Co2 Response ◽  
Transdiaphragmatic Pressure ◽  
Co2 Rebreathing ◽  
Inspiratory Muscle Fatigue

We evaluated the effect of global inspiratory muscle fatigue on ventilation and respiratory muscle control during CO2 rebreathing in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. CO2 response curves were measured before and after fatigue. During CO2 rebreathing, global fatigue caused a decreased tidal volume (VT) and an increased breathing frequency but did not change minute ventilation, duty cycle, or mean inspiratory flow. Both esophageal and transdiaphragmatic pressure swings were significantly reduced after global fatigue, suggesting decreased contribution of both rib cage muscles and diaphragm to breathing. End-expiratory transpulmonary pressure for a given CO2 was lower after fatigue, indicating an additional decrease in end-expiratory lung volume due to expiratory muscle recruitment, which leads to a greater initial portion of inspiration being passive. This, combined with the reduction in VT, decreased the fraction of VT attributable to inspiratory muscle contribution; therefore the inspiratory muscle elastic work and power per breath were significantly reduced. We conclude that respiratory control mechanisms are plastic and that the respiratory centers alter their output in a manner appropriate to the contractile state of the respiratory muscles to conserve the ventilatory response to CO2.

The effect of opioids on inspiratory muscle fatigue during inspiratory resistive loading

1993 ◽  
Vol 13 (4) ◽  
pp. 349-360 ◽  
Author(s):  
T. Wanke ◽  
H. Lahrmann ◽  
D. Formanek ◽  
B. Zwick ◽  
M. Merkle ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Inspiratory Muscle ◽  
Resistive Loading ◽  
Inspiratory Muscle Fatigue

Metabolic basis for inspiratory muscle fatigue in normal humans

1993 ◽  
Vol 75 (5) ◽  
pp. 2188-2194
Author(s):  
E. T. Mannix ◽  
T. Y. Sullivan ◽  
P. Palange ◽  
I. R. Dowdeswell ◽  
F. Manfredi ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Respiratory Muscles ◽  
Inspiratory Muscle ◽  
Inspiratory Pressure ◽  
Inspiratory Muscles ◽  
Normal Humans ◽  
Controlled Breathing ◽  
Metabolic Basis ◽  
O2 Supply ◽  
Inspiratory Muscle Fatigue

Inspiratory muscle fatigue, a common event in patients in the intensive care unit, is under multifactorial control. To test the hypothesis that systemic oxygenation is a factor in this event, we subjected five healthy males (age 42 +/- 3 yr) to continuous inspiratory pressure (75% of maximal inspiratory pressure, -95 +/- 5 cmH2O) with the use of a controlled breathing pattern while they breathed normoxic (21% O2), hyperoxic (30% O2), and hypoxic (13% O2) mixtures. Inspiratory muscle endurance (IME; time that pressure could be maintained) and other cardiorespiratory parameters were monitored. Room air IME (3.3 +/- 0.4 min) was shortened (P < 0.05) during 13% O2 breathing (1.6 +/- 0.4 min) but was unaffected during 30% O2 breathing (4.0 +/- 0.6 min). Inspiratory loading lowered the respiratory exchange ratio (RER) during the 21 and 30% O2 trials (1.02 +/- 0.01 to 0.80 +/- 0.03% and 1.05 +/- 0.05 to 0.69 +/- 0.01%, respectively) but not during the 13% O2 trials (1.03 +/- 0.03 to 1.06 +/- 0.07%). At the point of fatigue during the 13% O2 trials, RER was lower compared with the same time point during the 21 and 30% O2 trials. A significant relationship was observed between IME and RER (r = -0.73, P = 0.002) but not between IME and any of the other measured variables. We conclude that 1) hypoxemia impairs the ability of the inspiratory muscles to sustain a mechanical challenge and 2) substrate utilization of the respiratory muscles shifts toward a greater reliance on lipid metabolism when O2 is readily available; this shift was not observed when the O2 supply was reduced.

Effect of inspiratory muscle fatigue on breathing pattern

1985 ◽  
Vol 59 (4) ◽  
pp. 1152-1158 ◽  
Author(s):  
C. G. Gallagher ◽  
V. I. Hof ◽  
M. Younes
Keyword(s):  
Muscle Fatigue ◽  
Breathing Pattern ◽  
Fixed Ratio ◽  
Normal Subjects ◽  
Inspiratory Muscle ◽  
Breathing Patterns ◽  
Mechanical Fatigue ◽  
Resistive Breathing ◽  
Significant Difference ◽  
Inspiratory Muscle Fatigue

Our aim was to determine whether inspiratory muscle fatigue changes breathing pattern and whether any changes seen occur before mechanical fatigue develops. Nine normal subjects breathed through a variable inspiratory resistance with a predetermined mouth pressure (Pm) during inspiration and a fixed ratio of inspiratory time to total breath duration. Breathing pattern after resistive breathing (recovery breathing pattern) was compared with breathing pattern at rest and during CO2 rebreathing (control breathing pattern) for each subject. Relative rapid shallow breathing was seen after mechanical fatigue and also in experiments with electromyogram evidence of diaphragmatic fatigue where Pm was maintained at the predetermined level during the period of resistive breathing. In contrast there was no significant difference between recovery and control breathing patterns when neither mechanical nor electromyogram fatigue was seen. It is suggested that breathing pattern after inspiratory muscle fatigue changes in order to minimize respiratory sensation.

Effect of inspiratory muscle fatigue on perception of effort during loaded breathing

1987 ◽  
Vol 62 (1) ◽  
pp. 300-307 ◽  
Author(s):  
G. S. Supinski ◽  
S. J. Clary ◽  
H. Bark ◽  
S. G. Kelsen
Keyword(s):  
Muscle Fatigue ◽  
Duty Cycle ◽  
Normal Subjects ◽  
Progressive Increase ◽  
Inspiratory Muscle ◽  
Sense Of Effort ◽  
Inspiratory Muscles ◽  
Pressure Time ◽  
Loaded Breathing ◽  
Inspiratory Muscle Fatigue

The present study examined the relationship between the intensity of the sense of effort during inspiratory threshold loading and the severity of inspiratory muscle fatigue. Studies were performed on normal subjects in whom the magnitude of airway pressure developed (Pm) and the duty cycle of breathing (TI/TT) were constrained to achieve a pressure-time integral (i.e., Pm/Pmax X TI/TT) 24% of maximum. In separate trials, the same pressure-time index (24%) was achieved using two widely different patterns of pressure magnitude and duty cycle to allow the effects of changes in the pattern of inspiratory muscle contraction on sensation and fatigue to be assessed. The intensity of the sense of effort was assessed using a category (Borg) scale. The severity of inspiratory muscle fatigue was assessed both from changes in the centroid frequency of the diaphragm electromyogram and from changes in the maximum static inspiratory pressure. Loaded breathing produced inspiratory muscle fatigue and a progressive increase in the sense of effort over time in all subjects. The rate at which the inspiratory muscles fatigued was the same with the two patterns of loading. In contrast, the rate of growth in the intensity of the sense of effort varied significantly as a function of the pattern of loaded breathing. The sense of effort increased at a faster rate with the high pressure-short duty cycle pattern of contraction as compared with the low pressure-long duty cycle pattern. As a result, the intensity of the sense of effort was not uniquely related to the severity of inspiratory muscle fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of respiratory muscle fatigue on subsequent exercise performance

1991 ◽  
Vol 70 (5) ◽  
pp. 2059-2065 ◽  
Author(s):  
M. J. Mador ◽  
F. A. Acevedo
Keyword(s):  
Oxygen Consumption ◽  
Visual Analogue Scale ◽  
Muscle Fatigue ◽  
Exercise Performance ◽  
Analogue Scale ◽  
Inspiratory Muscle ◽  
Respiratory Effort ◽  
Respiratory Muscle Fatigue ◽  
Subsequent Performance ◽  
Inspiratory Muscle Fatigue

The purpose of this study was to determine whether induction of inspiratory muscle fatigue might impair subsequent exercise performance. Ten healthy subjects cycled to volitional exhaustion at 90% of their maximal capacity. Oxygen consumption, breathing pattern, and a visual analogue scale for respiratory effort were measured. Exercise was performed on three separate occasions, once immediately after induction of fatigue, whereas the other two episodes served as controls. Fatigue was achieved by having the subjects breathe against an inspiratory threshold load while generating 80% of their predetermined maximal mouth pressure until they could no longer reach the target pressure. After induction of fatigue, exercise time was reduced compared with control, 238 +/- 69 vs. 311 +/- 96 (SD) s (P less than 0.001). During the last minute of exercise, oxygen consumption and heart rate were lower after induction of fatigue than during control, 2,234 +/- 472 vs. 2,533 +/- 548 ml/min (P less than 0.002) and 167 +/- 15 vs. 177 +/- 12 beats/min (P less than 0.002). At exercise isotime, minutes ventilation and the visual analogue scale for respiratory effort were larger after induction of fatigue than during control. In addition, at exercise isotime, relative tachypnea was observed after induction of fatigue. We conclude that induction of inspiratory muscle fatigue can impair subsequent performance of high-intensity exercise and alter the pattern of breathing during such exercise.

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