Dissociation between diaphragmatic and rib cage muscle fatigue

1988 ◽  
Vol 64 (3) ◽  
pp. 959-965 ◽  
Author(s):  
J. W. Fitting ◽  
T. D. Bradley ◽  
P. A. Easton ◽  
M. J. Lincoln ◽  
M. D. Goldman ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Normal Subjects ◽  
Breathing Patterns ◽  
Recruitment Pattern ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Resistive Breathing ◽  
Emg Power Spectrum ◽  
The Mean ◽  
Substantial Degree

To assess rib cage muscle fatigue and its relationship to diaphragmatic fatigue, we recorded the electromyogram (EMG) of the parasternal intercostals (PS), sternocleidomastoid (SM), and platysma with fine wire electrodes and the EMG of the diaphragm (DI) with an esophageal electrode. Six normal subjects were studied during inspiratory resistive breathing. Two different breathing patterns were imposed: mainly diaphragmatic or mainly rib cage breathing. The development of fatigue was assessed by analysis of the high-to-low (H/L) ratio of the EMG. To determine the appropriate frequency bands for the PS and SM, we established their EMG power spectrum by Fourier analysis. The mean and SD for the centroid frequency was 312 ± 16 Hz for PS and 244 ± 48 Hz for SM. When breathing with the diaphragmatic patterns, all subjects showed a fall in H/L of the DI and none had a fall in H/L of the PS or SM. During rib cage emphasis, four out of five subjects showed a fall in H/L of the PS and five out of six showed a fall in H/L of the SM. Four subjects showed no fall in H/L of the DI; the other two subjects were unable to inhibit diaphragm activity to a substantial degree and did show a fall in H/L of the DI. Activity of the platysma was minimal or absent during diaphragmatic emphasis but was usually strong during rib cage breathing. We conclude that fatigue of either the diaphragm or the parasternal and sternocleidomastoid can occur independently according to the recruitment pattern of inspiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of thoracoabdominal breathing patterns on inspiratory effort sensation

1987 ◽  
Vol 62 (4) ◽  
pp. 1665-1670 ◽  
Author(s):  
J. W. Fitting ◽  
D. A. Chartrand ◽  
T. D. Bradley ◽  
K. J. Killian ◽  
A. Grassino
Keyword(s):  
Normal Subjects ◽  
Motor Command ◽  
Esophageal Pressure ◽  
Inspiratory Effort ◽  
Breathing Patterns ◽  
Borg Scale ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Main Variable ◽  
Unique Relationship

The respiratory sensations evoked by added inspiratory loads are currently thought to be largely mediated by the activity of the inspiratory muscles. Because of the differences in proprioceptors and in afferent and efferent innervations among the inspiratory muscles, we hypothesized that the sensation evoked by a given load would be different when the motor command is directed mainly to rib cage muscles or mainly to the diaphragm. To test this hypothesis, we studied six normal subjects breathing against several inspiratory resistances while emphasizing the use of rib cage muscles, or the diaphragm, or a combination of both. At the end of 10 loaded breaths the subjects rated the perceived magnitude of inspiratory effort on a Borg scale. A linear and unique relationship (r = 0.96 +/- 0.02; P less than 0.001) was found between the sensation and esophageal pressure (Pes) in the three thoracoabdominal breathing patterns. We conclude that the level of Pes, whether generated mainly by the rib cage muscles or the diaphragm, is the main variable related to the sensation of inspiratory effort under external inspiratory loads.

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.

Oxygen cost of resistive-loaded breathing in quadriplegia

1992 ◽  
Vol 73 (3) ◽  
pp. 825-831 ◽  
Author(s):  
H. Manning ◽  
F. D. McCool ◽  
S. M. Scharf ◽  
E. Garshick ◽  
R. Brown
Keyword(s):  
Chest Wall ◽  
Energy Cost ◽  
Regression Line ◽  
Normal Subjects ◽  
Oxygen Cost ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Residual Capacity ◽  
Loaded Breathing ◽  
The Mean

We hypothesized that, in quadriplegia, chest wall distortion would increase the energy cost of ventilation. To assess this, we measured the oxygen cost of breathing (VO2 resp) and changes in chest wall configuration during inspiratory resistive-loaded breathing tasks in five quadriplegic and five normal subjects. Each subject performed three breathing tasks that spanned a range of work rates (Wtot). Configurational changes of the abdomen and upper, lower, and transverse rib cage were assessed with magnetometers. We found that 1) in both groups, VO2resp increased linearly with Wtot over the range of tasks performed, 2) the mean slope of the regression line of VO2resp vs. Wtot was greater for quadriplegic than for normal subjects (3.7 +/- 0.8 vs. 2.0 +/- 0.7 ml O2/J, P less than 0.01), 3) efficiency of breathing (Wtot/VO2resp) was less for quadriplegic than for normal subjects (1.9 +/- 0.6 vs. 3.5 +/- 1.4%, P less than 0.001), 4) during inhalation, upper and lower rib cages behaved similarly in the two groups, but the quadriplegic subjects had a decrease in transverse rib cage and a much greater increase in abdomen than normal subjects, and 5) functional residual capacity decreased in normal but not in quadriplegic subjects during the breathing tasks. We conclude that the lesser efficiency of breathing in quadriplegia may be related to the elastic work of chest wall distortion, shorter mean operational diaphragm length, and possibly differences between normal and quadriplegic subjects in mechanical advantage of available inspiratory muscles.

Breathing Patterns and Regional Ventilation Distribution in Tetraplegic Patients and in Normal Subjects

1972 ◽  
Vol 42 (2) ◽  
pp. 117-128 ◽  
Author(s):  
B. Bake ◽  
A. R. Fugl-Meyer ◽  
G. Grimby
Keyword(s):  
Tidal Volume ◽  
Cervical Spinal Cord ◽  
Regional Distribution ◽  
Normal Subjects ◽  
Airway Disease ◽  
Breathing Patterns ◽  
Rib Cage ◽  
Small Airway Disease ◽  
Residual Capacity ◽  
Traumatic Transection

1. The regional distribution of ventilation was studied with 133Xe techniques in the sitting position in six patients with complete traumatic transection of the cervical spinal cord, 3–40 months after the lesion, and in four normal subjects. The relative contributions of the rib cage and abdomen to ventilation were determined from chest-wall motions. 2. Total lung capacity (TLC) was decreased and residual volume increased in the patients. After correction for the decreased TLC, the distribution of the regional functional residual capacity in the tetraplegic patients was similar to that of the normal subjects. In the patients, where the abdomen contributed to about half of the tidal volume, decreased ventilation of basal regions was demonstrated from measurements of regional tidal volumes (Vtr) and regional 133Xe wash-in curves. 3. The distribution of ventilation in normal persons, however, was not changed by varying the relative contributions of the rib cage and abdomen to the tidal volume, as shown from Vtr and regional 133Xe wash-out measurements. 4. The results in the tetraplegic patients are interpreted as evidence of ‘small airway disease’, presumably from infection of the air way and impairment of the cough.

Expiratory muscle fatigue in normal subjects

1991 ◽  
Vol 70 (6) ◽  
pp. 2632-2639 ◽  
Author(s):  
S. Suzuki ◽  
J. Suzuki ◽  
T. Okubo
Keyword(s):  
Muscle Fatigue ◽  
Low Frequency ◽  
Normal Subjects ◽  
Work Load ◽  
Emg Activity ◽  
Transdiaphragmatic Pressure ◽  
Expiratory Muscle ◽  
Inspiratory Muscles ◽  
Loaded Breathing ◽  
Low Frequency Power

We examined expiratory muscle fatigue during expiratory resistive loading in 11 normal subjects. Subjects breathed against expiratory resistances at their own breathing frequency and tidal volume until exhaustion or for 60 min. Respiratory muscle strength was assessed from both the maximum static expiratory and inspiratory mouth pressures (PEmax and PImax). At the lowest resistance, PEmax and PImax measured after completion of the expiratory loaded breathing were not different from control values. With higher resistance, both PEmax and PImax were decreased (P less than 0.05), and the decrease lasted for greater than or equal to 60 min. The electromyogram high-to-low frequency power ratio for the rectus abdominis muscle decreased progressively during loading (P less than 0.01), but the integrated EMG activity did not change during recovery. Transdiaphragmatic pressure during loading was increased 3.6-fold compared with control (P less than 0.05). These findings suggest that expiratory resistive loaded breathing induces muscle fatigue in both expiratory and inspiratory muscles. Fatigue of the expiratory muscles can be attributed directly to the high work load and that of the inspiratory muscles may be related to increased work due to shortened inspiratory time.

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.

Maximal shortening of inspiratory muscles: effect of training

1983 ◽  
Vol 54 (6) ◽  
pp. 1618-1623 ◽  
Author(s):  
C. H. Fanta ◽  
D. E. Leith ◽  
R. Brown
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Training Group ◽  
Normal Subjects ◽  
Pressure Control ◽  
Base Line ◽  
Lung Capacity ◽  
Inspiratory Muscles ◽  
The Mean

Normal subjects can increase their vital capacity by appropriate training. We tested whether that change can be achieved by greater maximal shortening of the inspiratory muscles without concomitant increases in peak static inspiratory pressures. Sixteen healthy volunteers participated in the study: eight were randomly assigned to make 20 inhalations to total lung capacity, held for 10 s with the glottis open, each day for 6 wk; the remainder served as nontraining controls. Before and after the 6-wk study period, we made multiple determinations of lung volumes and of curves relating lung volume to maximal static inspiratory (and expiratory) pressure. Control subjects had no significant changes from base line in any variable. In the training group, the mean vital capacity increased 200 +/- 74 ml (P less than 0.05) or 3.9 +/- 1.3% (P less than 0.02), without a significant change in residual volume. After training, the mean maximal inspiratory pressure at the airway opening (PI) at a lung volume equal to the base-line total lung capacity was 27 +/- 8 cmH2O in this group (vs. zero before training; P less than 0.02). Values of PI in the mid-vital capacity range did not change. We conclude that in response to appropriate training stimuli inspiratory muscles can contract to shorter minimal lengths, a capacity potentially important in progressive pulmonary hyperinflation.

Decay of inspiratory muscle pressure during expiration in anesthetized kyphoscoliosis patients

1992 ◽  
Vol 72 (2) ◽  
pp. 712-720 ◽  
Author(s):  
A. Baydur
Keyword(s):  
Flow Resistance ◽  
Relaxation Method ◽  
Normal Subjects ◽  
Respiratory Impedance ◽  
Elastic Recoil ◽  
Intrinsic Resistance ◽  
Inspiratory Muscles ◽  
The Mean ◽  
Work Done ◽  
Mean Time

The decay of pressure developed by the inspiratory muscles during expiration (PmusI) has not been studied in subjects with increased respiratory impedance such as in kyphoscoliosis. PmusI was compared in 11 anesthetized patients with kyphoscoliosis with that in 11 anesthetized normal subjects. PmusI was obtained according to the following equation: PmusI(t) = Ers.V(t) - K1V(t) - K2V2(t), where V is volume and V is airflow at any instant t during spontaneous expiration, Ers is the passive elastance, and K1V + K2V2 is the flow resistance (curvilinear in both groups because of the endotracheal tube and the intrinsic resistance in the kyphoscoliotics) of the total respiratory system. Ers was determined by the relaxation method and resistance from the ensuing V-V relationships during the ensuing relaxed expiration. Changes in impedance due to pliometric work done by the inspiratory muscles during relaxation were neglected. Subjects in both groups showed marked braking of expiratory flow by PmusI. The mean time for PmusI to decrease to 50 and 0% amounted to 17 and 8% less, respectively, in the kyphoscoliosis group. Average values for flow-resistive work in the control and kyphoscoliosis groups both amounted to approximately 40% of the elastic energy stored during inspiration. The remaining portion, used as negative work, amounted to approximately 60% in both groups. Expiratory braking in anesthetized kyphoscoliotic patients appears to be in proportion to their magnitude of elastic recoil and intrinsic flow resistance.

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.

Synergistic behavior of inspiratory muscles after diaphragmatic fatigue in the newborn

1981 ◽  
Vol 51 (3) ◽  
pp. 547-551 ◽  
Author(s):  
J. M. Lopes ◽  
N. L. Muller ◽  
M. H. Bryan ◽  
A. C. Bryan
Keyword(s):  
Muscle Fatigue ◽  
Frequency Spectrum ◽  
Muscle Activity ◽  
Newborn Infants ◽  
Intercostal Muscle ◽  
Rib Cage ◽  
Intercostal Muscles ◽  
Inspiratory Muscles ◽  
Diaphragmatic Fatigue ◽  
Synergistic Behavior

We studied diaphragmatic and intercostal muscle activity and the pattern of motion of rib cage and abdomen after diaphragmatic muscle fatigue in 15 newborn infants (birth wt 1,251 +/- 424 g, mean +/- SD). Rib cage and abdominal motion were monitored with magnetometers and intercostal and diaphragmatic electromyograms (EMG's) with surface electrodes. Twelve infants showed a total of 66 episodes of muscle fatigue identified by EMG frequency spectrum analysis. Two patterns of responses to fatigue were observed. In the first case, five infants consistently recruited their intercostal muscles; this was followed by a normalization of the diaphragmatic frequency spectrum. In these infants, recruitment of intercostal muscles successfully prevented any clinical deterioration. In the second, seven infants showed no change in their intercostal muscle activity, and diaphragmatic fatigue was followed by apnea. We conclude that in newborn infants the synergistic behavior of the diaphragm and intercostal muscles can maximize the performance of these muscles and, in some infants, seems to prevent development of apnea.

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