Inspiratory Muscle Fatigue

Roussos, Charis; Macklem, Peter T.

doi:10.1002/cphy.cp030329

Cited by 23 publications

(18 citation statements)

References 81 publications

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“…Therefore, the PTImus results of all infants would be expected to lie far from the fatigue threshold. These results, however, indicate an increased effectiveness of inspiratory muscles of infants with the I/I ACE genotype, due to a lower energy demand and thus to a lower risk of respiratory muscle fatigue, under conditions that increase inspiratory load 35, 36. The findings of this study suggest that in clinical practice, infants with I/I ACE genotype, if supported by mechanical ventilation, may succeed extubation more often than infants with I/D and D/D ACE genotypes or may have a lower risk of respiratory failure under conditions that increase inspiratory load, such as respiratory infections.…”

Section: Discussionmentioning

confidence: 71%

Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants

Dimitriou¹,

Papakonstantinou²,

Stavrou³

et al. 2010

Pediatr. Pulmonol.

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Section: Discussionmentioning

confidence: 71%

Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants

Dimitriou¹,

Papakonstantinou²,

Stavrou³

et al. 2010

Pediatr. Pulmonol.

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“…a relative hypoventilation. The fatigue of the respiratory muscles is generally due to a failure of 1) the processes for delivering sufficient electrical activation from the central nervous system to the muscle, 2) the metabolic and enzymatic processes providing energy for contractile mechanisms and 3) the excitation-contraction coupling process (Roussos and Macklem 1986). Therefore, the possible respiratory muscle fatigue observed in this study could occur for the same TABLE 2: Packed cell volume (PCV) after exercise; changes in HC0,-ions (AHCOd), in total protein (ATP), in skin temperature (AST); rectal temperature after the SET (RT); changes in body weight (ABW), in phosphocreatine kinase (ACK) and lactate dehydrogenase (ALDH) activities, in circulating cortisol (ACortisol) and in P-endorphin level (Apendorphin) level recorded in Standardbred horses after a standardised treadmill test performed in TC and HHC.…”

Section: Pulmona P Ventilationmentioning

confidence: 99%

Respiratory adjustments in unacclimatised horses exercised under hot, humid conditions

Art

Lekeux

1995

Equine Veterinary Journal

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SummaryThe purpose of this study was to investigate the effect of a hot and humid environment on the pattern of breathing and the gas exchange in heavily exercising horses. Five healthy fit Standardbred horses were investigated twice at 8 day intervals, once in temperate conditions (TC) (ambient temperature: 15°C; relative humidity: 55%) and once in hot and humid conditions (HHC) (ambient temperature: 30°C; relative humidity: 75%). The standardised treadmill exercise test consisted of 8 rnin warm-up and 8 min exercise (1 rnin at 1.7,4,7,8,9 and 10 m / s and 2 rnin at 4 m/s with a 6% slope). Running in HHC induced a significant decrease in peak expired minute volume &), oxygen uptake (~O Z ) , qCOz and oxygen pulse, while RQ remained unchanged and PAC02 increased. The changes in skin temperature (ST), i.e. the difference between ST at rest and at 10 m/s, was dramatically higher in HHC. The test induced changes, i.e. the differences between the values before and after the test, in cortisol, pendorphins and plasma lactate (LA) values after the test were significantly higher. This study showed that performing a strenuous exercise in hot, humid conditions in unacclimatised horses induced a reduction of the aerobic capacity, i.e. decrease of the 9 0 2 and increase of LA production. A relative hypoventilation could be partly responsible for this observation, but all the steps of the oxygen transport from the pulmonary ventilation to the muscle metabolism could also potentially be impaired in such conditions. exertion also limit performance (Carlson 1987). However, the physiological mechanisms responsible for the impairment of exercise capability in hot, humid conditions in the equine species have received much less attention. Each step of the oxygen line, i.e. pulmonary ventilation, alveolar capillary gas exchange, gas transport in the blood from the lung to the working muscles and energy transformation in the muscle, could potentially be impaired during exercise in hot humid conditions. The aim of this study was to assess the effect of a high relative humidity and temperature on the ventilation and the cardiorespiratory adjustments to strenuous exercise in unacclimatised horses. Materials and methods Horses

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“…5 Under the former circumstances respiratory muscles are prone to fatigue and ventilatory failure may eventually ensue. 6 Measurements of respiratory muscle strength and endurance during asthma in remission may help to identify subjects who can be at special risk of respiratory muscle fatigue during an acute attack because of respiratory muscle weakness, due to malnutrition, 7 lack of fitness, concomitant metabolic disorders, or other systemic diseases. 8 During the past 10 years, several methods have been developed to measure respiratory muscle strength [9][10][11][12] and endurance.…”

Section: Introductionmentioning

confidence: 99%

Maximal inspiratory pressure and inspiratory muscle endurance time in asthmatic children: Reproducibility and relationship with pulmonary function tests

et al. 1997

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Respiratory muscle strength, assessed by maximal inspiratory mouth pressure (Pi,max), and endurance, assessed as the length of time a subject could breathe against inspiratory resistance with a target mouth pressure ≥70% of Pi,max (Tlim), were measured in 20 symptomless asthmatic children, in order to assess the reproducibility of such measurements and their relationship to traditional pulmonary function tests or tests of bronchial hyperresponsiveness. After recording lung volumes and bronchial response to methacholine, Pi,max and Tlim were measured twice in the same morning, with a 30‐minute interval between each experimental trial. Mean (±SD) values of Pi,max were 72.2 ± 20.6 cmH2O in the first and 75.8 ± 22.9 cmH2O in the second trial. Tlim was 154 ± 65 and 164 ± 66 seconds in the first and in the second trial respectively. A lack of agreement between different measurements was seen for both Pi,max and Tlim. The coefficient of repeatability was 24.8 for Pi,max and 92.3 for Tlim. A significant correlation between age and Pi,max as well as between body mass index and Pi,max were shown; no similar correlation was found for Tlim. No correlation was found between Pi,max and Tlim in either of the two successive runs or between either Pi,max or Tlim and lung volumes or bronchial response to methacholine. Our study shows that at this time the reproducibility of Pi,max or Tlim in children with asthma in remission seems to be poor, although Pi,max has a better reproducibility than Tlim. A standardized procedure to measure Pi,max, should be obtainable in the near future. This would improve its clinical usefulness since Pi,max is the only noninvasive test to assess respiratory muscle strength that can identify subjects at risk to develop respiratory muscle fatigue during an acute asthmatic attack. Pediatr. Pulmonol. 1997; 24:385–390. © 1997 Wiley‐Liss, Inc.

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Inspiratory Muscle Fatigue

Cited by 23 publications

References 81 publications

Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants

Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants

Respiratory adjustments in unacclimatised horses exercised under hot, humid conditions

Maximal inspiratory pressure and inspiratory muscle endurance time in asthmatic children: Reproducibility and relationship with pulmonary function tests

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