Regulation of ventilatory muscle blood flow

Hussain, Sabah N. A.

doi:10.1152/jappl.1996.81.4.1455

Cited by 21 publications

(14 citation statements)

References 123 publications

(152 reference statements)

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“…In intubated infants, the suppression of PEEP also induces an increase in tonic EAdi [25]. Elevated tonic EAdi may increase the risk of respiratory fatigue by increasing diaphragm metabolism in situations of possible inappropriate perfusion [25, 30, 31]. Increased tonic EAdi may reflect patient efforts to increase his EELV.…”

Section: Resultsmentioning

confidence: 99%

Interest of Monitoring Diaphragmatic Electrical Activity in the Pediatric Intensive Care Unit

Ducharme‐Crevier

Pont‐Thibodeau

Émériaud

2013

Critical Care Research and Practice

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The monitoring of electrical activity of the diaphragm (EAdi) is a new minimally invasive bedside technology that was developed for the neurally adjusted ventilatory assist (NAVA) mode of ventilation. In addition to its role in NAVA ventilation, this technology provides the clinician with previously unavailable and essential information on diaphragm activity. In this paper, we review the clinical interests of EAdi in the pediatric intensive care setting. Firstly, the monitoring of EAdi allows the clinician to tailor the ventilatory settings on an individual basis, avoiding frequent overassistance leading potentially to diaphragmatic atrophy. Increased inspiratory EAdi levels can also suggest insufficient support, while a strong tonic activity may reflect the patient efforts to increase its lung volume. EAdi monitoring also allows detection of patient-ventilator asynchrony. It can play a role in evaluation of extubation readiness. Finally, EAdi monitoring provides the clinician with better understanding of the ventilatory capacity of patients with acute neuromuscular disease. Further studies are warranted to evaluate the clinical impact of these potential benefits.

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Section: Resultsmentioning

confidence: 99%

Interest of Monitoring Diaphragmatic Electrical Activity in the Pediatric Intensive Care Unit

Ducharme‐Crevier

Pont‐Thibodeau

Émériaud

2013

Critical Care Research and Practice

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“…Conversely, exercise at lower intensities attenuates respiratory muscle fatigue, thus preventing the activation of the sympathetic vasoconstrictor efferent output to the locomotor muscles (Wetter et al 1999). Therefore, the restriction in both quadriceps and intercostal muscle blood flow beyond 80% WR max could be due to mediation of a muscle chemoreflex that originates from type III and IV thin fibre phrenic afferents in respiratory muscles (Hussain, 1996), causing sympatho‐excitation and vasoconstriction in several vascular beds including those of limb and respiratory muscles (Hussain, 1996). Secondary to respiratory muscle fatigue, limb vasoconstriction and reduced oxygen transport are expected to exacerbate locomotor muscle fatigue (Romer et al 2006), thereby triggering the limb muscle metaboreflex known to impact on systemic blood flow (Romer & Polkey, 2008).…”

Section: Discussionmentioning

confidence: 99%

Intercostal muscle blood flow limitation in athletes during maximal exercise

Vogiatzis

Athanasopoulos

Habazettl

et al. 2009

The Journal of Physiology

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We investigated whether, during maximal exercise, intercostal muscle blood flow is as high as during resting hyperpnoea at the same work of breathing. We hypothesized that during exercise, intercostal muscle blood flow would be limited by competition from the locomotor muscles. Intercostal (probe over the 7th intercostal space) and vastus lateralis muscle perfusion were measured simultaneously in ten trained cyclists by near-infrared spectroscopy using indocyanine green dye. Measurements were made at several exercise intensities up to maximal (WR max ) and subsequently during resting isocapnic hyperpnoea at minute ventilation levels up to those at WR max . During resting hyperpnoea, intercostal muscle blood flow increased linearly with the work of breathing (R 2 = 0.94) to 73.0 ± 8.8 ml min −1 (100 g) −1 at the ventilation seen at WR max (work of breathing ∼550-600 J min −1 ), but during exercise it peaked at 80% WR max (53.4 ± 10.3 ml min −1 (100 g) −1 ), significantly falling to 24.7 ± 5.3 ml min −1 (100 g)at WR max . At maximal ventilation intercostal muscle vascular conductance was significantly lower during exercise (0.22 ± 0.05 ml min −1 (100 g) −1 mmHg −1 ) compared to isocapnic hyperpnoea (0.77 ± 0.13 ml min −1 (100 g) −1 mmHg −1 ). During exercise, both cardiac output and vastus lateralis muscle blood flow also plateaued at about 80% WR max (the latter at 95.4 ± 11.8 ml min −1 (100 g) −1 ). In conclusion, during exercise above 80% WR max in trained subjects, intercostal muscle blood flow and vascular conductance are less than during resting hyperpnoea at the same minute ventilation. This suggests that the circulatory system is unable to meet the demands of both locomotor and intercostal muscles during heavy exercise, requiring greater O 2 extraction and likely contributing to respiratory muscle fatigue.

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“…The maintained diaphragm activity during expiration likely keeps diaphragm muscle tension higher than if it were relaxed, increasing the diaphragm's metabolism and potentially reducing diaphragm blood circulation (27), both factors that will make the diaphragm more susceptible to peripheral muscular fatigue. In the past, respiratory muscle fatigue was predicted using indices such as the pressure time product or tension time index.…”

Section: Discussionmentioning

confidence: 99%

Diaphragm Electrical Activity During Expiration in Mechanically Ventilated Infants

et al. 2006

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ABSTRACT:The presence of diaphragm electrical activity (EAdi) during expiration is believed to be involved in the maintenance of end-expiratory lung volume (EELV) and has never been studied in intubated and mechanically ventilated infants. The aim of this study was to quantify the amplitude of diaphragm electrical activity present during expiration in mechanically ventilated infants and to measure the impact of removing positive end-expiratory pressure (PEEP) on this activity. We studied the EAdi in 16 ready-to-be weaned intubated infants who were breathing on their prescribed ventilator and PEEP settings. In all 16 patients, 5 min of data were collected on the prescribed ventilator settings. In a subset of eight patients, the PEEP was briefly reduced to zero PEEP (ZEEP). EAdi was recorded with miniaturized sensors placed on a conventional nasogastric feeding tube. Airway pressure (Paw) was also measured. For each spontaneous breath, we identified the neural inspiration and neural expiration. Neural expiration was divided into quartiles (Q1, Q2, Q3, and Q4), and the amplitude of EAdi calculated for each Q1-Q4 represented 95 Ϯ 29%, 31 Ϯ 15%, 15 Ϯ 8%, and 12 Ϯ 7%, respectively, of the inspiratory EAdi amplitude. EAdi for Q3-Q4 significantly increased during ZEEP, and decreased after reapplication of PEEP. These findings confirm that the diaphragm remains partially active during expiration in intubated and mechanically ventilated infants and that removal of PEEP affects this tonic activity. This could have potential implications on the management of PEEP in intubated infants. T he diaphragm is primarily known as an inspiratory muscle that is active during inspiration and relaxed during expiration. However, in healthy premature and full-term newborns, it has been demonstrated that electrical activity of the diaphragm, measured with electrodes on the surface of the chest wall, may persist throughout expiration, suggesting a "tonic" activity of the respiratory muscles (1-4). Lopes et al.(2) demonstrated that changes in tonic activity of the diaphragm were associated with changes in EELV and provided the original physiologic explanation that persistent diaphragmatic activity during the exhalation period helps to regulate EELV in infants . In healthy full-term or premature infants, the EELV is higher than the relaxation volume, the latter being determined by the passive mechanical properties of the respiratory system (1,3,5). It is only after 1 y of age that the EELV coincides with the relaxed lung volume (6); before this age, adapting reflexes must compensate for the reduced EELV. In newborns, persistence of diaphragm activity during expiration, in combination with the flow-braking action of the laryngeal adductor muscles (7), a high respiratory rate, and a reduced time-constant of the respiratory system, has been suggested to contribute to an active elevation of EELV (5,8 -11). However, in intubated and mechanically ventilated infants, the presence of an endotracheal tube does not allow for expiratory flow braking via...

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Regulation of ventilatory muscle blood flow

Cited by 21 publications

References 123 publications

Interest of Monitoring Diaphragmatic Electrical Activity in the Pediatric Intensive Care Unit

Interest of Monitoring Diaphragmatic Electrical Activity in the Pediatric Intensive Care Unit

Intercostal muscle blood flow limitation in athletes during maximal exercise

Diaphragm Electrical Activity During Expiration in Mechanically Ventilated Infants

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