scholarly journals Do women experience less diaphragmatic fatigue during inspiratory resistance loading?

2018 ◽  
Vol 596 (17) ◽  
pp. 3821-3822
Author(s):  
Timothy David Noakes
Keyword(s):  
Diaphragmatic Fatigue ◽  
Inspiratory Resistance

Electromyogram pattern of diaphragmatic fatigue

1979 ◽  
Vol 46 (1) ◽  
pp. 1-7 ◽  
Author(s):  
D. Gross ◽  
A. Grassino ◽  
W. R. Ross ◽  
P. T. Macklem
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Normal Subjects ◽  
Progressive Increase ◽  
Transdiaphragmatic Pressure ◽  
Diaphragmatic Fatigue ◽  
Inspiratory Resistance ◽  
Residual Capacity ◽  
Emg Power Spectrum ◽  
Pressure Generator

We studied the effect of breathing at various levels of transdiaphragmatic pressure (Pdi) on the EMG power spectrum of the diaphragm. The diaphragmatic EMG was measured simultaneously with a bipolar esophageal electrode (EE) and surface electrode (SE) placed on the ventral portion of the sixth and seventh intercostal spaces in five normal subjects breathing at functional residual capacity (FRC) against an inspiratory resistance. During each fatigue run the subjects generated a Pdi, with each inspiration, that was 25, 50, or 75% of maximum Pdi (Pdimax) for a period up to 15 min. During runs at 50 and 75% of the Pdimax, which are known to produce fatigue, we found for both EE and SE a progressive increase in the amplitude of the low-frequency (L = 20-46.7 Hz) and a decrease in the high-frequency (H = 150-350 Hz) component of the EMG. These changes were not seen at 25% of Pdimax. The diaphragmatic H/L ratio was independent of Pdi when the diaphragm was not fatigued. H/L fell while the diaphragm performed fatiguing work and this was more rapid at higher Pdi's. It was thus concluded that frequency spectrum analysis of the EMG can detect diaphragmatic fatigue reliably, prior to the time when the diaphragm fails as a pressure generator.

Effect of diaphragmatic fatigue on control of respiratory muscles and ventilation during CO2 rebreathing

1993 ◽  
Vol 75 (3) ◽  
pp. 1364-1370 ◽  
Author(s):  
S. Yan ◽  
I. Lichros ◽  
S. Zakynthinos ◽  
P. T. Macklem
Keyword(s):  
Minute Ventilation ◽  
Respiratory Muscles ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Gastric Pressure ◽  
Diaphragmatic Fatigue ◽  
Before And After ◽  
Inspiratory Resistance ◽  
End Tidal

We studied the influence of diaphragmatic fatigue on the control of ventilation and respiratory muscle contribution to pressure swings in six normal seated subjects. CO2 was rebreathed before and after diaphragmatic fatigue induced by breathing against an inspiratory resistance requiring 60% maximal transdiaphragmatic pressure with each breath until exhaustion. After diaphragmatic fatigue for a given level of end-tidal PCO2, we found that tidal volume, breathing frequency, minute ventilation, duty cycle, and mean inspiratory flow did not change; esophageal pressure swings were the same, but gastric and transdiaphragmatic pressure swings were decreased; and the slope of the transpulmonary pressure-gastric pressure relationship determined at zero flow points at end expiration and end inspiration was increased. End-expiratory transpulmonary pressure progressively decreased and end-expiratory gastric pressure progressively increased with increasing end-tidal PCO2 by the same magnitude before and after diaphragmatic fatigue. We conclude that diaphragmatic fatigue induces proportionately greater contributions of inspiratory rib cage muscles than of the diaphragm, which results in the preservation of ventilatory response to CO2 despite impaired diaphragmatic contractility.

scholarly journals Sex differences in diaphragmatic fatigue: the cardiovascular response to inspiratory resistance

2018 ◽  
Vol 596 (17) ◽  
pp. 4017-4032 ◽  
Author(s):  
Joseph F. Welch ◽  
Bruno Archiza ◽  
Jordan A. Guenette ◽  
Christopher R. West ◽  
A. William Sheel
Keyword(s):  
Sex Differences ◽  
Cardiovascular Response ◽  
Diaphragmatic Fatigue ◽  
Inspiratory Resistance

scholarly journals Senkung des intrakraniellen Drucks durch Senkung des zentralvenösen Drucks: Bewertung möglicher Gegenmaßnahmen zum Raumfahrt-assoziierten neuro-okulären Syndrom

2021 ◽  
pp. 1-2
Author(s):  
Sebastian Siebelmann
Keyword(s):  
Intracranial Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Free Breathing ◽  
Optic Disc Edema ◽  
Threshold Device ◽  
Inspiratory Resistance ◽  
Minimal Reduction ◽  
Clinical Conditions ◽  
Impedance Threshold Device

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, −7 cmH<sub>2</sub>O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; <i>P</i> = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; <i>P</i> = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, <i>P</i> = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, <i>P</i> = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; <i>P</i> = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; <i>P =</i>0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

Diaphragmatic Fatigue after Exercise in Healthy Human Subjects

1993 ◽  
Vol 148 (6_pt_1) ◽  
pp. 1571-1575 ◽  
Author(s):  
M. Jeffery Mador ◽  
Ulysses J. Magalang ◽  
Angel Rodis ◽  
Thomas J. Kufel
Keyword(s):  
Human Subjects ◽  
Healthy Human ◽  
Healthy Human Subjects ◽  
Diaphragmatic Fatigue

Respiratory mechanics in supine subjects during progressive partial curarization

1982 ◽  
Vol 52 (1) ◽  
pp. 57-63 ◽  
Author(s):  
T. J. Gal ◽  
N. S. Arora
Keyword(s):  
Muscle Strength ◽  
Muscle Weakness ◽  
Respiratory Mechanics ◽  
Handgrip Strength ◽  
Elastic Recoil ◽  
Lung Inflation ◽  
Progressive Muscle Weakness ◽  
Inspiratory Resistance ◽  
Residual Capacity ◽  
Partial Curarization

Respiratory mechanics were studied in six supine conscious volunteers during progressive muscle weakness produced by infusion of d-tubocurarine. Partial curarization was carried out to the point of abolishing head lift ability and handgrip strength. At all levels of partial paralysis, expiratory muscle strength was significantly more impaired than inspiratory strength. Despite this, subjects maintained relatively normal maximal expiratory flow rates, whereas inspiratory flows decreased significantly. The diminished inspiratory flows are not fully explained by decreased driving pressures during force inspiration, since inspiratory resistance increased significantly with the decreased flow. Inspiratory flow patterns suggest a variable extrathoracic obstruction most likely due to the absence of normal airway abductor activity during inspiration. Maximal respiratory muscle weakness decreased forced vital capacity by 29% and total lung capacity by 15%. The decreased level of lung inflation did not alter lung elastic recoil. Functional residual capacity was unchanged, but inspiratory capacity decreased by 25% and residual volume increased by 38%. These changes are in accord with predictions based on the decreased muscle strength and normal respiratory system recoil.

Detection of diaphragmatic fatigue in man by phrenic stimulation

1981 ◽  
Vol 50 (3) ◽  
pp. 538-544 ◽  
Author(s):  
M. Aubier ◽  
G. Farkas ◽  
A. De Troyer ◽  
R. Mozes ◽  
C. Roussos
Keyword(s):  
Phrenic Nerve ◽  
Chronic Obstructive Lung Disease ◽  
Chronic Obstructive ◽  
Low Frequencies ◽  
Transdiaphragmatic Pressure ◽  
Control Value ◽  
Transcutaneous Stimulation ◽  
Diaphragmatic Fatigue ◽  
Residual Capacity ◽  
Stimulation Of

Transdiaphragmatic pressure (Pdi) was measured at functional residual capacity (FRC) in four normal seated subjects during supramaximal, supraclavicular transcutaneous stimulation of one phrenic nerve (10, 20, 50, and 100 Hz--0.1 ms duration) before and after diaphragmatic fatigue, produced by breathing through a high alinear inspiratory resistance. Constancy of chest wall configuration was achieved by placing a cast around the abdomen and the lower one-fourth of the rib cage. Pdi increased with frequency of stimulation, so that at 10, 20, and 50 Hz, the Pdi generated was 32 +/- 4 (SE), 70 +/- 3, and 98 +/- 2% of Pdi at 100 Hz, respectively. After diaphragmatic fatigue, Pdi was less than control at all frequencies of stimulation. Recovery for high stimulation frequencies was complete at 10 min, but at low stimulation frequencies recovery was slow: after 30 min of recovery, Pdi at 20 Hz was 31 +/- 7% of the control value. It is concluded that diaphragmatic fatigue can be detected in man by transcutaneous stimulation of the phrenic nerve and that diaphragmatic strength after fatigue recovers faster at high than at low frequencies of stimulation. Furthermore, it is suggested that this long-lasting element of fatigue might occur in patients with chronic obstructive lung disease, predisposing them to respiratory failure.

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