Dyspnea: an update

Our understanding of the nature and mechanisms of dyspnea has greatly evolved over the last two centuries. Although the relationship was never form- ally specified, discomfort was always assumed to accompany respiratory muscle activity. Hypotheses and theories of dyspnea thus became synonymous with the factors controlling the extremes of respira- tory muscle activity, with expiratory muscle activity and discomfort now being known to be controlled by the same factors.

Vagal modulation of respiratory muscle activity in awake dogs during exercise and hypercapnia

10.1152/jappl.1992.72.4.1362 ◽

1992 ◽

Vol 72 (4) ◽

pp. 1362-1367 ◽

Cited By ~ 11

Author(s):

D. M. Ainsworth ◽

C. A. Smith ◽

B. D. Johnson ◽

S. W. Eicker ◽

K. S. Henderson ◽

...

Keyword(s):

Lung Volume ◽

Muscle Activity ◽

Respiratory Muscle ◽

Treadmill Exercise ◽

Rib Cage ◽

Expiratory Muscle ◽

Vagal Modulation ◽

Vagal Cooling ◽

Using chronically instrumented awake tracheotomized dogs, we examined the contributions of vagal feedback to respiratory muscle activities, both electrical and mechanical, during normoxic hypercapnia (inspired CO2 fraction = 0.03, 0.04, 0.05, and 0.06) and during mild treadmill exercise (3, 4.3, and 6.4 km/h). Cooling exteriorized vagal loops eliminated both phasic and tonic mechanoreceptor input during either of these hyperpneas. At a given chemical or locomotor stimulus, vagal cooling caused a further increase in costal, crural, parasternal, and rib cage expiratory (triangularis sterni) muscles. No further change in abdominal expiratory muscle activity occurred secondary to vagal cooling during these hyperpneas. However, removal of mechanoreceptor input during hypercapnia was not associated with consistent changes in end-expiratory lung volume, as measured by the He-N2 rebreathe technique. We conclude that during these hyperpneas 1) vagal input is not essential for augmentation of expiratory muscle activity and 2) decrements in abdominal expiratory muscle activity may be offset by increments in rib cage expiratory muscle activity and contribute to the regulation of end-expiratory lung volume.

Vagal contributions to respiratory muscle activity during eupnea in the awake dog

10.1152/jappl.1992.72.4.1355 ◽

1992 ◽

Vol 72 (4) ◽

pp. 1355-1361 ◽

Cited By ~ 8

Author(s):

D. M. Ainsworth ◽

C. A. Smith ◽

B. D. Johnson ◽

S. W. Eicker ◽

K. S. Henderson ◽

...

Keyword(s):

Electrical Activity ◽

Muscle Activity ◽

Respiratory Muscle ◽

Transversus Abdominis ◽

Emg Activity ◽

Expiratory Muscle ◽

Vagal Blockade ◽

Inspiratory Activity ◽

Vagal Cooling ◽

We examined the effects of reversible vagal cooling on respiratory muscle activities in awake chronically instrumented tracheotomized dogs. We specifically analyzed electromyographic (EMG) activity and its ventilatory correlates, end-expiratory lung volume (EELV) and diaphragmatic resting length via sonomicrometry. Elimination of phasic and tonic mechanoreceptor activity by vagal cooling doubled the EMG activity of the costal, crural, and parasternal muscles, with activation occurring sooner relative to the onset of inspiratory flow. Diaphragmatic postinspiration inspiratory activity in the intact dog coincided with a brief mechanical shortening of the diaphragm during early expiration; vagal blockade removed both the electrical activity and the mechanical shortening. Vagal blockade also doubled the EMG activity of a rib cage expiratory muscle, the triangularis sterni, but reduced that of an abdominal expiratory muscle, the transversus abdominis. Within-breath electrical activity of both muscles occurred sooner relative to the onset of expiratory flow during vagal blockade. Vagal cooling was also associated with a 12% increase in EELV and a 5% decrease in end-expiratory resting length of the diaphragm. We conclude that vagal input significantly modulates inspiratory and expiratory muscle activities, which help regulate EELV efficiently and optimize diaphragmatic length during eupneic breathing in the awake dog.

Sequence of respiratory muscle activity during varied vocal attack

Speech Monographs ◽

10.1080/03637756509375451 ◽

1965 ◽

Vol 32 (2) ◽

pp. 185-191 ◽

Cited By ~ 11

Author(s):

Michael S. Hoshiko ◽

Kenneth W. Berger

Keyword(s):

Muscle Activity ◽

Respiratory Muscle ◽

Cervical spinal V2a neurons pattern respiratory muscle activity and enhance ventilation

The FASEB Journal ◽

10.1096/fasebj.2020.34.s1.02972 ◽

2020 ◽

Vol 34 (S1) ◽

pp. 1-1

Author(s):

Victoria N. Jensen ◽

Azl Saeed ◽

Kari A. Seedle ◽

Sarah Marie Turner ◽

Steven A. Crone

Keyword(s):

Muscle Activity ◽

Respiratory Muscle ◽

Effects of Respiratory Muscle Activity in Stroke Patients after Feedback Breathing Exercise

Journal of international academy of physical therapy research ◽

10.5854/jiaptr.2013.10.25.552 ◽

2013 ◽

Vol 4 (2) ◽

pp. 552-556 ◽

Cited By ~ 2

Author(s):

Jong Man Han ◽

Hyeon Ae Kim ◽

Ja Pung Koo ◽

Kyo Chul Seo

Keyword(s):

Muscle Activity ◽

Respiratory Muscle ◽

Stroke Patients ◽

Breathing Exercise ◽

Respiratory Muscle Effort during Expiration in Successful and Failed Weaning from Mechanical Ventilation

Anesthesiology ◽

10.1097/aln.0000000000002256 ◽

2018 ◽

Vol 129 (3) ◽

pp. 490-501 ◽

Cited By ~ 20

Author(s):

Jonne Doorduin ◽

Lisanne H. Roesthuis ◽

Diana Jansen ◽

Johannes G. van der Hoeven ◽

Hieronymus W. H. van Hees ◽

...

Keyword(s):

Mechanical Ventilation ◽

Electrical Activity ◽

Muscle Activity ◽

Respiratory Muscle ◽

Weaning From Mechanical Ventilation ◽

Expiratory Muscle ◽

Diaphragm Electrical Activity ◽

Gastric Pressure ◽

Weaning Failure ◽

Expiratory Muscles

Abstract What We Already Know about This Topic What This Article Tells Us That Is New Background Respiratory muscle weakness in critically ill patients is associated with difficulty in weaning from mechanical ventilation. Previous studies have mainly focused on inspiratory muscle activity during weaning; expiratory muscle activity is less well understood. The current study describes expiratory muscle activity during weaning, including tonic diaphragm activity. The authors hypothesized that expiratory muscle effort is greater in patients who fail to wean compared to those who wean successfully. Methods Twenty adult patients receiving mechanical ventilation (more than 72 h) performed a spontaneous breathing trial. Tidal volume, transdiaphragmatic pressure, diaphragm electrical activity, and diaphragm neuromechanical efficiency were calculated on a breath-by-breath basis. Inspiratory (and expiratory) muscle efforts were calculated as the inspiratory esophageal (and expiratory gastric) pressure–time products, respectively. Results Nine patients failed weaning. The contribution of the expiratory muscles to total respiratory muscle effort increased in the “failure” group from 13 ± 9% at onset to 24 ± 10% at the end of the breathing trial (P = 0.047); there was no increase in the “success” group. Diaphragm electrical activity (expressed as the percentage of inspiratory peak) was low at end expiration (failure, 3 ± 2%; success, 4 ± 6%) and equal between groups during the entire expiratory phase (P = 0.407). Diaphragm neuromechanical efficiency was lower in the failure versus success groups (0.38 ± 0.16 vs. 0.71 ± 0.36 cm H2O/μV; P = 0.054). Conclusions Weaning failure (vs. success) is associated with increased effort of the expiratory muscles and impaired neuromechanical efficiency of the diaphragm but no difference in tonic activity of the diaphragm.

Respiratory Origin of Fluctuations in Arterial Blood Pressure in Premature Infants With Respiratory Distress Syndrome

PEDIATRICS ◽

10.1542/peds.81.3.399 ◽

1988 ◽

Vol 81 (3) ◽

pp. 399-403

Author(s):

Jeffrey Perlman ◽

Bradley Thach

Keyword(s):

Premature Infants ◽

Muscle Activity ◽

Intraventricular Hemorrhage ◽

Respiratory Muscle ◽

Pressure Fluctuations ◽

Esophageal Pressure ◽

Arterial Blood ◽

Gastric Pressure ◽

Pressure Changes ◽

A variable fluctuating pattern of arterial BP often precedes intraventricular hemorrhage in mechanically ventilated preterm infants. To learn more about the origin of this pattern, arterial BP and respiratory muscle activity were studied in five intubated premature infants who were at high risk for intraventricular hemorrhage. We monitored esophageal pressure, gastric pressure, and arterial BP. Consistent findings were: (1) arterial BP fluctuations have the same frequency and direction of change as esophageal and gastric pressure changes associated with spontaneous breathing (R ranged from .93 to .98, P < .001); (2) spontaneous apneic pauses were accompanied by sudden and complete cessation of arterial BP fluctuations; (3) large "cough-like" fluctuations in esophageal and gastric pressures, seen in all infants, were associated with the largest fluctuations in arterial BP; (4) cutaneous stimulation had negligible effect on fluctuation in arterial BP provided no change in esophageal and gastric pressures occurred; (5) the effects of change in esophageal and gastric pressures on arterial BP were nearly simultaneous (0.05 to 0.25 second latency); (6) respirator pressure fluctuations had negligible effects on the fluctuations in arterial BP. These data suggest that the fluctuations in arterial BP are directly related to respiratory muscle activity and are most consistent with the familiar pulsus paradoxus that occurs in various other cardiorespiratory diseases.

Changes in respiratory muscle activity in ponies when end-expiratory lung volume is increased

10.1152/jappl.1994.76.5.2015 ◽

1994 ◽

Vol 76 (5) ◽

pp. 2015-2025 ◽

Cited By ~ 8

Author(s):

B. K. Erickson ◽

H. V. Forster ◽

T. F. Lowry ◽

L. G. Pan ◽

M. J. Korducki ◽

...

Keyword(s):

Tidal Volume ◽

Lung Volume ◽

Negative Pressure ◽

Muscle Activity ◽

Respiratory Muscle ◽

Transversus Abdominis ◽

Vagal Afferents ◽

Breathing Frequency ◽

The objective of the present study was to determine whether lung and diaphragm afferents contribute to the changes in respiratory muscle activity when end-expiratory lung volume (EELV) is changed in ponies. We studied the responses of the diaphragm and the transversus abdominis (TA) muscles to passive increases in EELV in awake intact (I), diaphragm-deafferented (DD), pulmonary vagal- (hilar nerve) denervated (HND), and DD + HND ponies. Negative pressure of -10 or -20 cmH2O applied around the ponies′ torsos [positive transrespiratory (TR) pressure] increased (P < 0.05) EELV in all ponies; the increases were more (P < 0.05) in HND and less (P < 0.05) in DD than in I ponies. In I ponies, positive TR pressure increased (P < 0.05) the rate of rise of the integrated diaphragmatic electromyogram (EMG), reflecting increased drive to the muscle. This increase was less (P < 0.05) in DD and HND than in I ponies. In DD + HND ponies, there was no significant (P > 0.10) change in drive to the diaphragm during positive TR pressure. In I ponies, positive TR pressure increased (P < 0.05) the duration and mean activity of the TA EMG. In HND and DD + HND ponies, the TA EMG was not altered by positive TR pressure. I and DD ponies decreased (P < 0.05) breathing frequency but maintained tidal volume (VT) during positive TR pressure. HND and DD+HND ponies increased breathing frequency (P < 0.05) and decreased (P < 0.05) VT during positive TR pressure. We conclude that, during positive TR pressure when the diaphragm is presumably at a mechanical disadvantage, diaphragm and vagal afferents mediate increased drive to the diaphragm to prevent VT from decreasing. In addition, during positive TR pressure, vagal afferents mediate an increase in duration of TA activity, which minimizes the increase in EELV.

Effects of Inspiratory Load on Chest Wall Kinematics, Breathing Pattern, and Respiratory Muscle Activity of Mouth-Breathing Children

Respiratory Care ◽

10.4187/respcare.06908 ◽

2020 ◽

Vol 65 (9) ◽

pp. 1285-1294

Author(s):

Jéssica Danielle Medeiros da Fonsêca ◽

Vanessa Regiane Resqueti ◽

Kadja Benício ◽

Valéria Soraya de Farias Sales ◽

Luciana Fontes Silva da Cunha Lima ◽

...

Keyword(s):

Chest Wall ◽

Muscle Activity ◽

Respiratory Muscle ◽

Breathing Pattern ◽

Mouth Breathing ◽

Chest Wall Kinematics ◽

Respiratory Muscle Activity ◽

Inspiratory Load

Respiratory muscle activity during repeated airflow interruption

10.1152/jappl.1988.64.6.2314 ◽

1988 ◽

Vol 64 (6) ◽

pp. 2314-2317 ◽

Cited By ~ 10

Author(s):

J. Mead ◽

M. B. Reid

Keyword(s):

Muscle Activity ◽

Respiratory Muscle ◽

Rapid Succession ◽

Expiratory Muscles ◽

We observed striking differences in respiratory muscle electromyogram activity when active expirations were interrupted in rapid succession, depending on the mode of interruption. When the interruptions were produced at the level of the glottis (utterances, uh-uh-uh-uh, at 5–8 Hz) there were synchronous bursts of activity from expiratory muscles in all three subjects during the periods of no flow and rapid bursts of diaphragmatic activity during the flow phases in one subject. In contrast, when similarly rapid interruptions of active expirations were produced with the tongue on a mouthpiece (utterance, te-te-te-te) or with an external valve, no synchronous bursts were observed. Since all interruptions would have been mechanically similar at expiratory muscular and pulmonary levels, we reasoned that the bursts with glottic interruptions were either programmed centrally or driven reflexly at the laryngeal level.