Within-breath electromyographic changes during loaded breathing in adult sheep

1986 ◽  
Vol 61 (4) ◽  
pp. 1316-1321 ◽  
Author(s):  
G. G. Haddad ◽  
H. J. Jeng ◽  
A. R. Bazzy ◽  
T. L. Lai
Keyword(s):  
Marked Decrease ◽  
Emg Activity ◽  
Recruitment Pattern ◽  
Transdiaphragmatic Pressure ◽  
Adult Sheep ◽  
Diaphragmatic Muscle ◽  
Breathing Resistance ◽  
Resistive Breathing ◽  
Loaded Breathing ◽  
High Level

To investigate the changes in diaphragm electromyogram (EMG) during the course of severe loaded breathing, we subjected five conscious adult sheep to inspiratory flow resistive breathing (resistance greater than 150 cmH2O X l–1 X s) for up to 2–3 h and studied the total EMG power per breath (iEMG) and the EMG power per unit time after dividing the duration of EMG activity within each breath into three equal parts (iEMG1, iEMG2, and iEMG3). Both total breath iEMG and transdiaphragmatic pressure (Pdi) increased, remained at a high level for a certain period of time, and then started to fall. A change in the pattern of iEMG within a breath was observed during loaded breathing. The increase in total-breath iEMG was associated mostly with an increase in iEMG3, or the last part of the EMG power within each inspiration. Similarly, the decrease in total breath iEMG was primarily due to a decrease in iEMG3. We conclude that, in sheep subjected to severe IFR loads for prolonged periods the marked increase in total-breath iEMG at the beginning of loaded breathing and the marked decrease in this iEMG at the time of decrease in Pdi are largely due to changes in iEMG that occur during the latter third of each breath. We speculate that during loaded breathing the recruitment pattern of diaphragmatic muscle fibers changes during the course of an inspiratory effort.

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.

Effect of inspiratory resistive loaded breathing and hypoxemia on diaphragmatic function in the piglet

1992 ◽  
Vol 73 (5) ◽  
pp. 1888-1893 ◽  
Author(s):  
D. E. Mayock ◽  
T. A. Standaert ◽  
D. E. Woodrum
Keyword(s):  
Blood Flow ◽  
Blood Gases ◽  
Muscle Lactate ◽  
Transdiaphragmatic Pressure ◽  
Diaphragmatic Muscle ◽  
Diaphragmatic Function ◽  
Significant Augmentation ◽  
Significant Impairment ◽  
Loaded Breathing ◽  
Lactate Levels

The combined effects of inspiratory resistive loaded breathing (IRL) and hypoxemia on transdiaphragmatic pressure (Pdi) in nine 1-mo-old Yorkshire piglets were studied. IRL was adjusted to increase spontaneously generated Pdi five to six times above baseline but maintain arterial PCO2 < 70 Torr to prevent hypercapnic depression of diaphragmatic contractility. Measurements of ventilation, blood gases and pH, Pdi, diaphragmatic electromyogram, Pdi during phrenic nerve stimulation, diaphragmatic blood flow, and end-expiratory lung volume were obtained at baseline, after 2 h of IRL, and then after 1 h of hypoxemia (arterial PO2 approximately 40 Torr) combined with IRL. Diaphragmatic muscle samples were obtained after study completion and immediately frozen in liquid nitrogen for determination of tissue ATP, phosphocreatine, lactate, and glycogen levels. Ten 1-mo-old piglets were subjected to IRL alone and served as controls. IRL alone resulted in significant impairment of Pdi generation. The addition of hypoxemia for 1 h did not further compromise Pdi in comparison to control animals who were subjected to IRL alone. Blood flow to both the costal and crural segments of the diaphragm increased significantly during IRL; the addition of the hypoxemic stress resulted in further significant augmentation of blood flow to both segments of the diaphragm. No differences were noted in diaphragmatic muscle tissue ATP, phosphocreatine, or glycogen between control and IRL animals or between control and IRL plus hypoxemia animals. Muscle lactate levels increased significantly in the IRL plus hypoxemia animals only. The data from this study suggest that moderate hypoxemia during resistive-loaded breathing in the piglet does not accentuate diaphragmatic fatigue.

IMPORTANCE OF MOTIVATION IN TOLERABILITY OF INCREASED BREATHING RESISTANCE

2019 ◽  
pp. 72-79
Author(s):  
Yu.Yu. Byalovskiy ◽  
I.S. Rakitina
Keyword(s):  
Functional State ◽  
Maximum Level ◽  
Technological Environment ◽  
Breathing Control ◽  
Aerodynamic Loads ◽  
Breathing Resistance ◽  
Resistive Breathing ◽  
Resistive Loads ◽  
Intraoral Pressure

Cortical mechanisms play an important role in breathing control under increased breathing resistance (resistive loads). Cortical mechanisms determine the level of voluntary motivation, which significantly affects the tolerance of resistive breathing loads. The purpose of the paper is to determine the effect of voluntary motivation on the tolerance of additional breathing resistance. Materials and Methods. The authors formed procedural motivation by means of moral encouragement or financial rewards of the subjects. Simulation of increased breathing resistance was performed using in-creasing values of thresholdless inspiratory aerodynamic loads: 40, 60, 70, and 80 % from the maximum intraoral pressure. Results. The maximum level of tolerance of additional breathing resistance was observed in volunteers with a material and subsidiary procedural motivation of activity. Under respiratory loads, these subjects demonstrated the greatest deviations of the functional state indicators. Undefined motivation based on the mobilization of goal-oriented resources with moral stimulation showed less efficiency. Lack of specially formed procedural motivation led to minimal tolerance of resistive loads. Conclusion. Procedural motivation, aimed at overcoming additional breathing resistance, significantly increases the tolerance of individual protective means of respiratory organs, which maintains health of workers in a polluted technological environment. Keywords: motivation, tolerance, increased breathing resistance. Большую роль в регуляции дыхания при увеличенном сопротивлении дыханию (резистивных нагрузках) играют кортикальные механизмы. Корковые механизмы определяют уровень произвольной мотивации, которая существенно влияет на переносимость резистивных дыхательных нагрузок. Цель исследования – определение влияния произвольной мотивации на переносимость дополнительного респираторного сопротивления. Материалы и методы. Процессуальную мотивацию формировали методом морального или материального поощрения испытуемых. Моделирование увеличенного сопротивления дыханию проводили с помощью предъявления возрастающих значений беспороговых инспираторных аэродинамических нагрузок: 40, 60, 70 и 80 % от максимального внутриротового давления. Результаты. Максимальный уровень переносимости дополнительного респираторного сопротивления наблюдался у добровольцев, у которых была сформирована материально-субсидивная процессуальная мотивация деятельности; у этой категории испытуемых во время действия дыхательных нагрузок отмечались наибольшие отклонения показателей функционального состояния. Произвольная мотивация на основе мобилизации волевых ресурсов при моральном стимулировании характеризовалась меньшей эффективностью, а отсутствие специально сформированной процессуальной мотивации сопровождалось минимальной переносимостью резистивных нагрузок. Выводы. Процессуальная мотивация, сформированная для преодоления дополнительного респираторного сопротивления, существенно повышает переносимость средств индивидуальной защиты органов дыхания, что имеет большое значение для сохранения здоровья работающих в условиях загрязненной производственной среды. Ключевые слова: мотивация, переносимость, увеличенное сопротивление дыханию.

Respiratory Activity of the Rat Posterior Cricoarytenoid Muscle

1997 ◽  
Vol 106 (11) ◽  
pp. 897-901 ◽  
Author(s):  
Robert G. Berkowitz ◽  
John Chalmers ◽  
Qi-Jian Sun ◽  
Paul M. Pilowsky
Keyword(s):  
Phrenic Nerve ◽  
Muscle Activity ◽  
Electrophysiological Study ◽  
Emg Activity ◽  
Diaphragmatic Muscle ◽  
Posterior Cricoarytenoid Muscle ◽  
Inspiratory Activity ◽  
Intramuscular Nerve ◽  
Posterior Cricoarytenoid ◽  
Nerve Discharge

An anatomic and electrophysiological study of the rat posterior cricoarytenoid (PCA) muscle is described. The intramuscular nerve distribution of the PCA branch of the recurrent laryngeal nerve was demonstrated by a modified Sihler's stain. The nerve to the PCA was found to terminate in superior and inferior branches with a distribution that appeared to be confined to the PCA muscle. Electromyography (EMG) recordings of PCA muscle activity in anesthetized rats were obtained under stereotaxic control together with measurement of phrenic nerve discharge. A total of 151 recordings were made in 7 PCA muscles from 4 rats. Phasic inspiratory activity with a waveform similar to that of phrenic nerve discharge was found in 134 recordings, while a biphasic pattern with both inspiratory and post-inspiratory peaks was recorded from random sites within the PCA muscle on 17 occasions. The PCA EMG activity commenced 24.6 ± 2.2 milliseconds (p < .0001) before phrenic nerve discharge. The results are in accord with findings of earlier studies that show that PCA muscle activity commences prior to inspiratory airflow and diaphragmatic muscle activity. The data suggest that PCA and diaphragm motoneurons share common or similar medullary pre-motoneurons. The earlier onset of PCA muscle activity may indicate a role for medullary pre-inspiratory neurons in initiating PCA activity.

Ventilatory failure during loaded breathing: the role of central neural drive

1988 ◽  
Vol 65 (1) ◽  
pp. 249-255 ◽  
Author(s):  
J. F. Watchko ◽  
T. A. Standaert ◽  
D. E. Mayock ◽  
G. Twiggs ◽  
D. E. Woodrum
Keyword(s):  
Minute Ventilation ◽  
Respiratory Muscles ◽  
Muscle Performance ◽  
Emg Activity ◽  
Base Line ◽  
Force Frequency ◽  
Peripheral Muscle ◽  
Arterial Blood ◽  
Loaded Breathing ◽  
Ventilatory Failure

Minute ventilation (VE), arterial blood gases, diaphragmatic electromyogram (EMG) activity, centroid frequency (Fc) and peak inspiratory airway pressures (Paw) were measured in five unanesthetized tracheostomized infant monkeys during various intensities of inspiratory resistive loaded breathing (IRL) until either 1) ventilatory failure occurred (failed trial) or 2) normocapnia was sustained for 1 h (successful trial). During successful trials VE and arterial PCO2 (PaCO2) were sustained at base-line levels, and an increase in peak integrated diaphragmatic EMG activity and peak inspiratory Paw occurred. In contrast, during ventilatory failure runs, VE decreased and PaCO2 rose compared with their respective base-line values. The fall in VE occurred secondary to a significant decline in breathing frequency. Tidal volume was sustained at base-line levels during all trials (both successful and failed groups). Inspiratory Paw's and peak moving time average EMG were sustained at elevated levels during ventilatory failure runs, suggesting that the respiratory muscles did not fail as pressure generators. Furthermore, the EMG Fc did not change from base line during either successful or failed trials. These data suggest that peripheral muscle fatigue did not occur, although in the absence of a more direct test of muscle performance, i.e., a force-frequency curve, we cannot rule out the possibility that a component of peripheral failure contributed to our results. Ventilatory failure during severe IRL in the infant monkey was most clearly associated with an alteration in the respiratory center timing mechanism, i.e., such failure was a function of a decline in respiratory frequency.

Specificity of esophageal electrode recordings of posterior cricoarytenoid muscle activity

1989 ◽  
Vol 66 (3) ◽  
pp. 1501-1505 ◽  
Author(s):  
G. Insalaco ◽  
G. Sant'Ambrogio ◽  
F. B. Sant'Ambrogio ◽  
S. T. Kuna ◽  
O. P. Mathew
Keyword(s):  
Marked Decrease ◽  
Upper Airway ◽  
Emg Activity ◽  
Small Reduction ◽  
Posterior Cricoarytenoid Muscle ◽  
Intramuscular Electrodes ◽  
Inspiratory Activity ◽  
Recorded Activity ◽  
Posterior Cricoarytenoid ◽  
The Right

Esophageal electrodes have been used for recording the electromyographic (EMG) activity of the posterior cricoarytenoid muscle (PCA). To determine the specificity of this EMG technique, esophageal electrode recordings were compared with intramuscular recordings in eight anesthetized mongrel dogs. Intramuscular wire electrodes were placed in the right and left PCA, and the esophageal electrode was introduced through the nose or mouth and advanced into the upper esophagus. On direct visualization of the upper airway, the unshielded catheter electrode entered the esophagus on the right or left side. Cold block of the recurrent laryngeal nerve (RLN) ipsilateral to the esophageal electrode was associated with a marked decrease in recorded activity, whereas cold block of the contralateral RLN resulted only in a small reduction in activity. After supplemental doses of anesthesia were administered, bilateral RLN cold block essentially abolished the activity recorded with the intramuscular electrodes as well as that recorded with the esophageal electrode. Before supplemental doses of anesthesia were given, especially after vagotomy, the esophageal electrode, and in some cases the intramuscular electrodes, recorded phasic inspiratory activity not originating from the PCA. Therefore, one should be cautious in interpreting the activity recorded from esophageal electrodes as originating from the PCA, especially in conditions associated with increased respiratory efforts.

scholarly journals Intercostal muscle motor behavior during tracheal occlusion conditioning in conscious rats

2016 ◽  
Vol 120 (7) ◽  
pp. 792-800 ◽  
Author(s):  
Poonam B. Jaiswal ◽  
Paul W. Davenport
Keyword(s):  
Respiratory Activity ◽  
Motor Behavior ◽  
Respiratory Muscles ◽  
Experimental Period ◽  
Emg Activity ◽  
Intercostal Muscle ◽  
Load Compensation ◽  
Conscious Rats ◽  
Loaded Breathing ◽  
Conscious Animals

A respiratory load compensation response is characterized by increases in activation of primary respiratory muscles and/or recruitment of accessory respiratory muscles. The contribution of the external intercostal (EI) muscles, which are a primary respiratory muscle group, during normal and loaded breathing remains poorly understood in conscious animals. Consciousness has a significant role on modulation of respiratory activity, as it is required for the integration of behavioral respiratory responses and voluntary control of breathing. Studies of respiratory load compensation have been predominantly focused in anesthetized animals, which make their comparison to conscious load compensation responses challenging. Using our established model of intrinsic transient tracheal occlusions (ITTO), our aim was to evaluate the motor behavior of EI muscles during normal and loaded breathing in conscious rats. We hypothesized that 1) conscious rats exposed to ITTO will recruit the EI muscles with an increased electromyogram (EMG) activation and 2) repeated ITTO for 10 days would potentiate the baseline EMG activity of this muscle in conscious rats. Our results demonstrate that conscious rats exposed to ITTO respond by recruiting the EI muscle with a significantly increased EMG activation. This response to occlusion remained consistent over the 10-day experimental period with little or no effect of repeated ITTO exposure on the baseline ∫EI EMG amplitude activity. The pattern of activation of the EI muscle in response to an ITTO is discussed in detail. The results from the present study demonstrate the importance of EI muscles during unloaded breathing and respiratory load compensation in conscious rats.

Pattern of recovery from diaphragmatic fatigue over 24 hours

1995 ◽  
Vol 79 (2) ◽  
pp. 539-546 ◽  
Author(s):  
F. Laghi ◽  
N. D'Alfonso ◽  
M. J. Tobin
Keyword(s):  
Marked Decrease ◽  
Experimental Protocol ◽  
Transdiaphragmatic Pressure ◽  
Twitch Potentiation ◽  
Fatigue Protocol ◽  
Resistive Loading ◽  
Diaphragmatic Fatigue ◽  
Rate Of Recovery ◽  
Phrenic Nerves ◽  
Stimulation Of

The rate of recovery from diaphragmatic fatigue beyond 1 h is unknown. To investigate this question, we studied 12 healthy subjects and measured transdiaphragmatic twitch pressure (Pditw) using magnetic stimulation of the phrenic nerves. Measurements were obtained at baseline and after a fatigue protocol consisting of inspiratory resistive loading in which the subjects generated 60% of maximal transdiaphragmatic pressure until task failure. At baseline, Pditw was 38.9 +/- 1.1 (SE) cmH2O and fell to 25.1 +/- 0.6 cmH2O 10 min after the conclusion of the fatigue protocol (P < 0.01). Pditw increased to 27.6 +/- 0.9, 31.6 +/- 1.1, and 32.7 +/- 1.2 cmH2O 1, 8 and 24 h, respectively, after the conclusion of the fatigue protocol; the 24-h value was significantly lower than baseline (P < 0.01). The nadir in Pditw after the protocol was delayed by 10 min. In separate experiments, we showed that this delay was probably due to the development of twitch potentiation as a result of forceful diaphragmatic contractions during the fatigue protocol. In conclusion, induction of diaphragmatic fatigue with this experimental protocol produced a marked decrease in diaphragmatic contractility that persisted for at least 24 h.

Diaphragmatic force and substrate response to resistive loaded breathing in the piglet

1991 ◽  
Vol 70 (1) ◽  
pp. 70-76 ◽  
Author(s):  
D. E. Mayock ◽  
T. A. Standaert ◽  
T. D. Murphy ◽  
D. E. Woodrum
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Blood Gases ◽  
Force Frequency ◽  
Frequency Curve ◽  
Transdiaphragmatic Pressure ◽  
Diaphragmatic Muscle ◽  
Generating Capacity ◽  
Crural Diaphragm ◽  
Spontaneous Contractions

Inspiratory resistive loaded (IRL) breathing results in hypoventilation and diaphragmatic fatigue in the piglet. We studied the effects of 6 h of IRL on ten 1-mo-old piglets. The load was adjusted to increase spontaneously generated transdiaphragmatic pressure five to six times baseline. Six 1-mo-old piglets acted as controls and were identically instrumented but were not subjected to IRL. Measurements of ventilation, blood gases and pH, diaphragmatic electromyogram, force-frequency curve, blood flow, and end-expiratory lung volume were obtained hourly. Diaphragmatic muscle samples were obtained after 6 h for determination of ATP, phosphocreatine, lactate, and glycogen levels. No changes occurred in the control animals. IRL resulted in a significant decrease in ventilation, an increase in diaphragmatic EMG, onset of abdominal expiratory muscle activity, and a fall in end-expiratory lung volume by 1 h. The force-frequency curve adjusted for lung volume change fell by 20% at all frequencies of stimulation at 1 h and by 40% at 6 h. Blood flow to the costal and crural diaphragm increased by 51 and 141%, respectively. No differences were noted in ATP, phosphocreatine, lactate, or glycogen between control and IRL animals. It is concluded that submaximal spontaneous contractions of the piglet diaphragm over a 6-h period cause a substantial decrease in its maximal force-generating capacity that is not related to substrate depletion.

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)

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