Unity of costal and crural diaphragmatic activity in respiration

Pollard, Marcus J.; Megirian, D.; Sherrey, J.H.

doi:10.1016/0014-4886(85)90051-2

Cited by 14 publications

(7 citation statements)

References 14 publications

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“…In conclusion, the use of the crural diaphragm EMG RMS value to infer global diaphragm activation can be considered to be valid at physiological activation levels and at nonextreme chest wall configurations. Our findings are in agreement with previous investigators' reports on homogeneity between costal and crural diaphragm activation during breathing (7,21,24,27,28).…”

supporting

confidence: 94%

Effects of lung volume on diaphragm EMG signal strength during voluntary contractions

Beck

Sinderby

Lindström

et al. 1998

Journal of Applied Physiology

143

115

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The use of esophageal recordings of the diaphragm electromyogram (EMG) signal strength to evaluate diaphragm activation during voluntary contractions in humans has recently been criticized because of a possible artifact created by changes in lung volume. Therefore, the first aim of this study was to evaluate whether there is an artifactual influence of lung volume on the strength of the diaphragm EMG during voluntary contractions. The second aim was to measure the required changes in activation for changes in lung volume at a given tension, i.e., the volume-activation relationship of the diaphragm. Healthy subjects (n = 6) performed contractions of the diaphragm at different transdiaphragmatic pressure (Pdi) targets (range 20-160 cmH2O) while maintaining chest wall configuration constant at different lung volumes. The diaphragm EMG was recorded with a multiple-array esophageal electrode, with control of signal contamination and electrode positioning. The effects of lung volume on the EMG were studied by comparing the crural diaphragm EMG root mean square (RMS), an index of crural diaphragm activation, with an index of global diaphragm activation obtained by normalizing Pdi to the maximum Pdi at the given muscle length (Pdi/Pdimax@L) at the different lung volumes. We observed a direct relationship between RMS and Pdi/Pdimax@L independent of diaphragm length. The volume-activation relationship of the diaphragm was equally affected by changes in lung volume as the volume-Pdi relationship (60% change from functional residual capacity to total lung capacity). We conclude that the RMS of the diaphragm EMG is not artifactually influenced by lung volume and can be used as a reliable index of diaphragm activation. The volume-activation relationship can be used to infer changes in the length-tension relationship of the diaphragm at submaximal activation/contraction levels.

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supporting

confidence: 94%

Effects of lung volume on diaphragm EMG signal strength during voluntary contractions

Beck

Sinderby

Lindström

et al. 1998

Journal of Applied Physiology

143

115

View full text Add to dashboard Cite

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“…Rat motor unit activity appears uniform in the crural and costal segments with inspiration and non-ventilatory behaviors [44], [45], and injurious mechanical loads typically induce greater rat costal than crural diaphragmatic remodeling [21], [30]. However, the phrenic neural distribution may be greater in the crural region [46], and some cuff inflations could have occurred at times other than end-exhalation, resulting in occasional crural motor unit recruitment during the expiratory phase of ventilation [47].…”

Section: Discussionmentioning

confidence: 99%

Chronic Intrinsic Transient Tracheal Occlusion Elicits Diaphragmatic Muscle Fiber Remodeling in Conscious Rodents

et al. 2012

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BackgroundAlthough the prevalence of inspiratory muscle strength training has increased in clinical medicine, its effect on diaphragm fiber remodeling is not well-understood and no relevant animal respiratory muscle strength training-rehabilitation experimental models exist. We tested the postulate that intrinsic transient tracheal occlusion (ITTO) conditioning in conscious animals would provide a novel experimental model of respiratory muscle strength training, and used significant increases in diaphragmatic fiber cross-sectional area (CSA) as the primary outcome measure. We hypothesized that ITTO would increase costal diaphragm fiber CSA and further hypothesized a greater duration and magnitude of occlusions would amplify remodeling.Methodology/Principal FindingsSprague-Dawley rats underwent surgical placement of a tracheal cuff and were randomly assigned to receive daily either 10-minute sessions of ITTO, extended-duration, 20-minute ITTO (ITTO-20), partial obstruction with 50% of cuff inflation pressure (ITTO-PAR) or observation (SHAM) over two weeks. After the interventions, fiber morphology, myosin heavy chain composition and CSA were examined in the crural and ventral, medial, and dorsal costal regions. In the medial costal diaphragm, with ITTO, type IIx/b fibers were 26% larger in the medial costal diaphragm (p<0.01) and 24% larger in the crural diaphragm (p<0.05). No significant changes in fiber composition or morphology were detected. ITTO-20 sessions also yielded significant increases in medial costal fiber cross-sectional area, but the effects were not greater than those elicited by 10-minute sessions. On the other hand, ITTO-PAR resulted in partial airway obstruction and did not generate fiber hypertrophy.Conclusions/SignificanceThe results suggest that the magnitude of the load was more influential in altering fiber cross-sectional area than extended-duration conditioning sessions. The results also indicated that ITTO was associated with type II fiber hypertrophy in the medial costal region of the diaphragm and may be an advantageous experimental model of clinical respiratory muscle strength training.

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“…However, the close correlation of the electrical activity in the crural and the costal parts has been well documented in humans during respiratory tasks [52,53]. The EMG recorded from the costal diaphragm was similar to that from the crus in terms of synchronous activation and time course in both quiet and loaded breathing [48,51,54]. Lastly, in a series of studies, Sharshar et al [18] showed that the effect of various respiratory tasks on the diaphragm MEP was the same whether measured from oesophageal or surface electrodes.…”

Section: Figure 1 Cmap Recorded Simultaneously From Lower Chest Wall mentioning

confidence: 81%

Diaphragm electromyography using an oesophageal catheter: current concepts

2008

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The usefulness of diaphragm electromyography recorded from an oesophageal electrode depends on a reliable signal which is free of artefact. The diaphragm EMG (electromyogram) recorded from chest wall surface electrodes may be unreliable because of signal contamination from muscle activity other than the diaphragm. Initially, the oesophageal electrode catheter for human studies had only one electrode pair, which could be difficult to position accurately and was influenced by a change in lung volume. Recently, a multipair oesophageal electrode has been developed which allows a high-quality EMG to be recorded. In the present review, the progress of oesophageal electrode design is outlined. The effects of signal contamination, electrode movement and particularly the effect of change in lung volume on the diaphragm EMG are discussed. The diaphragm EMG, recorded from a multipair oesophageal electrode, is useful to assess neural respiratory drive and diaphragm function in different groups of patients with respiratory disease, including patients with neuromuscular disease and sleep-disordered breathing, and those in the intensive care unit. When combined with cervical and cranial magnetic stimulation, an oesophageal electrode can be used to partition the central respiratory response time and phrenic nerve conduction time.

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Unity of costal and crural diaphragmatic activity in respiration

Cited by 14 publications

References 14 publications

Effects of lung volume on diaphragm EMG signal strength during voluntary contractions

Effects of lung volume on diaphragm EMG signal strength during voluntary contractions

Chronic Intrinsic Transient Tracheal Occlusion Elicits Diaphragmatic Muscle Fiber Remodeling in Conscious Rodents

Diaphragm electromyography using an oesophageal catheter: current concepts

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