Postural changes in spontaneous and evoked regional diaphragmatic activity in dogs

Brancatisano, A.; Kelly, Suzanne M.; Tully, A.; Loring, Stephen H.; Engel, L. A.

doi:10.1152/jappl.1989.66.4.1699

Cited by 20 publications

(12 citation statements)

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“…A frequently recurring criticism of the measurement of EAdi with esophageal or implanted electrodes during spontaneous breathing is that the signal strength is affected by changes in muscle length or lung volume. This critique is based on studies of evoked diaphragm compound muscle action potentials (15) or outdated methodology that does not control for interelectrode distance (16). Using appropriate methodology, EAdi obtained during spontaneous breathing is not artifactually influenced by changes in muscle length, chest wall configuration, or lung volume (17,18).…”

Section: Summary Of Findingsmentioning

confidence: 99%

Prolonged Neural Expiratory Time Induced by Mechanical Ventilation in Infants

et al. 2004

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Mechanical ventilation may interfere with the spontaneous breathing pattern in infants because they have strong reflexes that play a large role in the control of breathing. This study aimed to answer the following questions: does a ventilator-assisted breath 1) reduce neural inspiratory time, 2) reduce the amplitude of the diaphragm electrical activity, and 3) prolong neural expiration, within the delivered breath? In 14 infants recovering from acute respiratory failure (mean age and weight were 2.3 Ϯ 1.3 mo and 3.95 Ϯ 0.82 kg, respectively), we measured 1) the electrical activity of the diaphragm with a multiple-array esophageal electrode, and 2) airway opening pressure, while patients breathed on synchronized intermittent mandatory ventilation (mean rate, 11.2 Ϯ 6.5 breaths/min). We compared neural inspiratory and expiratory times for the mandatory breaths and for the spontaneous breaths immediately preceding and following the mandatory breath. Although neural inspiratory time was not different between mandatory and spontaneous breaths, neural expiratory time was significantly increased (p Ͻ 0.001) for the mandatory breaths (953 Ϯ 449 ms) compared with the premandatory and postmandatory spontaneous breaths (607 Ϯ 268 ms and 560 Ϯ 227 ms, respectively). Delivery of the mandatory breath resulted in a reduction in neural respiratory frequency by 28.6 Ϯ 6.4% from the spontaneous premandatory frequency. The magnitude of inspiratory electrical activity of the diaphragm was similar for all three breath conditions. For the mandatory breaths, ventilatory assist persisted for 507 Ϯ 169 ms after the end of neural inspiratory time. Infant-ventilator asynchrony (both inspiratory and expiratory asynchrony) was present in every mandatory breath and constituted 53.4 Ϯ 26.2% of the total breath duration. Newborn infants have strong reflexes that play a large role in the control of breathing (1). The work of Hering and Breuer in 1868 demonstrated in newborn animals that expansion of the lung reflexly inhibits inspiration-the HB inspiratoryinhibiting reflex-and promotes expiration-the HB expiratory-promoting reflex (2). With respect to mechanical ventilation in infants, it is reasonable to expect that delivery of ventilatory assistance should reflexly reduce neural Ti and neural inspiratory activity within the breath delivered. With respect to the HB expiratory-promoting reflex, one would expect an increase in neural Te during the assisted breath, compared with a spontaneous unassisted breath. The expiratory-promoting reflex has been clinically observed in mechanically ventilated infants, but was described with indirect estimates of neural timing (such as airway or esophageal pressure or flow) to gauge its effects (3-5). In addition to the fact that no quantitative evaluation of the reflex was made, the recent work of Parthasarathy et al. (6) has demonstrated that indirect estimates of respiratory timing are in poor agreement with more direct measurements of neural activity.Much of the available literature on reflex control of ...

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Section: Summary Of Findingsmentioning

confidence: 99%

Prolonged Neural Expiratory Time Induced by Mechanical Ventilation in Infants

et al. 2004

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“…The diaphragm in our animals, however, was not paralyzed. No attempt was made to record diaphragmatic EMG activity in the present study, because this activity, when recorded with intramuscular electrodes, is well known to show artifactual changes with alterations in the conductivity of the environment surrounding the electrodes (7) or in the length of the muscle fibers (19,22). However, similar to neural drive to the parasternal intercostals (10,11), neural drive to the diaphragm is primarily governed by supraspinal control mechanisms, and measurements of motoneuron synchronization in cats by Vaughan and Kirkwood (34) showed that phrenic motoneurons and parasternal intercostal motoneurons receive common monosynaptic inputs.…”

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confidence: 99%

Dysfunction of the canine respiratory muscle pump in ascites

Leduc¹,

Troyer²

2007

Journal of Applied Physiology

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Ascites, a complicating feature of many diseases of the liver and peritoneum, commonly causes dyspnea. The mechanism of this symptom, however, is uncertain. In the present study, progressively increasing ascites was induced in anesthetized dogs, and the hypothesis was initially tested that ascites increases the impedance on the diaphragm and, so, adversely affects the lung-expanding action of the muscle. Ascites produced a gradual increase in abdominal elastance and an expansion of the lower rib cage. Concomitantly, the caudal displacement of the diaphragm and the fall in airway opening pressure during isolated stimulation of the phrenic nerves decreased markedly; transdiaphragmatic pressure during phrenic stimulation also decreased. To assess the adaptation to ascites of the respiratory system overall, we subsequently measured the changes in lung volume, the arterial blood gases, and the electromyogram of the parasternal intercostal muscles during spontaneous breathing. Tidal volume and minute ventilation decreased progressively as ascites increased, leading to an increase in arterial PCO2 and parasternal intercostal inspiratory activity. It is concluded that 1) ascites, acting through an increase in abdominal elastance and an expansion of the lower rib cage, impairs the lung-expanding action of the diaphragm; 2) this impairment elicits a compensatory increase in neural drive to the inspiratory muscles, but the compensation is not sufficient to maintain ventilation; and 3) dyspnea in this setting results in part from the dissociation between increased neural drive and decreased ventilation.

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“…The asymmetrical non-respiratory activity in the left and right diaphragm was considered to be due to the changes in electrical environment [14]. However, it could not be the case in the present experiment, because the diaphragm in cats is smaller than that in dogs and small displacements by contraction may cause the relatively stable electrical recording environment.…”

Section: Activities During Free Movementmentioning

confidence: 71%

Activity patterns of diaphragm during voluntary movements in awake cats

Uga

Niwa²,

Ochiai

et al. 2007

Neuroscience Research

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Abstract:The diaphragm is an important inspiratory muscle, and also known to participate in the postural function. However, the activity of the diaphragm during voluntary movements has not been fully investigated in awake animals. In order to investigate the diaphragmatic activity during voluntary movements such as extending or rotating their body, we analyzed the electromyogram (EMG) of the diaphragm and trunk muscles in the cat using technique for simultaneous recordings of EMG signals and video images.Periodic respiratory discharges occurred in the left and right costal diaphragm when the cat kept still. However, once the cat moved, their periodicity and/or synchrony were sometimes buried by non-respiratory activity. Such non-periodic diaphragmatic activities during voluntary movements are considered as the combination of respiratory activity and non-respiratory activity. Most of the diaphragmatic activities started shortly after the initiation of standing-up movements and occurred after the onset of trunk muscle activities. Those activities were more active compared to the normal respiratory activity. During rotation movements, left and right diaphragmatic activities showed asymmetrical discharge patterns and higher discharges than those during the resting situation. This asymmetrical activity may be caused by taking different length of each side of the diaphragm and trunk muscles. During reaching movements, the diaphragmatic acitivitiey occurred prior to or with the onset of trunk muscle activities. It is likely that diaphragmatic activities during reaching movements and standing-up movements may have been controlled by some different control mechanisms of central nervous system. This study will discuss that the diaphragmatic activity is regulated not only by the respiratory center, but also by inputs from center for voluntary movements and/or sensory reflex pathways under awake condition. 3/23

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Postural changes in spontaneous and evoked regional diaphragmatic activity in dogs

Cited by 20 publications

References 0 publications

Prolonged Neural Expiratory Time Induced by Mechanical Ventilation in Infants

Prolonged Neural Expiratory Time Induced by Mechanical Ventilation in Infants

Dysfunction of the canine respiratory muscle pump in ascites

Activity patterns of diaphragm during voluntary movements in awake cats

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