Diaphragm compound muscle action potential measured with magnetic stimulation and chest wall surface electrodes

Luo, Y-M; Mustfa, Naveed; Lyall, RA; Man, William D.-C.; Glerant, J C H; Polkey, Michael I.; Moxham, John

doi:10.1016/s0034-5687(02)00010-5

Cited by 8 publications

(10 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The wide range for CMAPdi amplitudes is in agreement with those previously reported [5,13,17] and, interestingly, also occurs with ES [2] and between right and left hemidiaphragms of the same subject [2,6,23]. This variability between subjects has been attributed to: individual differences in muscle fibre conduction velocity, contraction intensity and recruitment of motors units [16]; anatomical differences, differences in chestwall thickness [24]; difficulty in maximally stimulating the phrenic nerve [5,10]; the choice of chest-wall electrode sites [13]; and the interelectrode distance, with greater interelectrode distance increasing contamination [25].…”

Section: Significance Of the Findingssupporting

confidence: 92%

“…The range of latencies obtained were comparable to [8,18] or slightly shorter than those previously reported [13,17] and may be a consequence of different recording sites; with latencies elicited from anterior electrodes being shorter than those from electrodes placed in the xyphoid position or close to the anterior axillary line [5,13]. As previously reported [14,17], increasing the intensity of UMS led to a decrease in CMAPdi latencies.…”

Section: Significance Of the Findingssupporting

confidence: 82%

“…Although the phrenic nerve is more reliably located using magnetic stimulation (MS), which has a wider field of activation and is more comfortable for patients [11], it may co-activate extradiaphragmatic chest wall muscle and contaminate the electromyogram (EMG) signal, affecting CMAPdi reproducibility [11,12]. However, it is possible to avoid co-activation of extradiaphragmatic muscles when performing MS of the phrenic nerves, particularly with careful placement of the stimulation coils [13], and silent EMG traces in patients with diaphragm paralysis have been recorded with surface electrodes during MS [14,15].…”

mentioning

confidence: 99%

“…Although a number of different sites have been reported for recording the diaphragm EMG using surface electrodes, the optimal position for achieving a reproducible CMAPdi is not well established. Different investigators have described a variety of positions for chest wall electrodes for MS, most commonly close to the anterior axillary line, the midclavicular line, or between the xyphoid process and the costal margin [8,13,17,18]. Various positions have also been presented for ES by investigators with the most common recording sites being the anterior axillary line over the sixth to the eighth intercostal spaces [2,8,9,17], between the xyphoid process and the costal margin [5] and in the eighth intercostal space close to the midclavicular line [19].…”

mentioning

confidence: 99%

See 3 more Smart Citations

Diaphragm electromyograms recorded from multiple surface electrodes following magnetic stimulation

Glerant

Mustfa²,

Man³

et al. 2006

European Respiratory Journal

View full text Add to dashboard Cite

The diaphragm compound-muscle action potential (CMAPdi), elicited by unilateral magnetic stimulation (UMS) of the phrenic nerve can be recorded using surface electrodes. However, there is no consensus on the best positioning of surface electrodes and there are no data on the reproducibility of the signal.Using 36 surface electrode pairs, in five healthy subjects, the CMAPdi elicited by UMS and electrical stimulation (ES) were compared and 12 pairs were identified as providing acceptable signals. The latency and amplitude were measured for each CMAPdi, following UMS at 60-100% of maximal stimulator output, in 12 healthy subjects, on two occasions.Latencies obtained using UMS and ES ranged between 6.1-7.33 and 6.25-7.17 ms, respectively. Optimum CMAPdi were not recorded from the same electrode pair in all subjects, or for both hemidiaphragms in each subject. However, the optimal recording site for a particular individual remained unchanged on subsequent testing. When recorded from the optimal site, latencies and amplitudes of CMAPdi elicited on the two occasions were not significantly different.The current study suggests that the use of multiple chest wall electrodes can identify an optimal electrode pair, from which it is possible to obtain reproducible compound-muscle action potential signals.

show abstract

Section: Significance Of the Findingssupporting

confidence: 92%

Section: Significance Of the Findingssupporting

confidence: 82%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Diaphragm electromyograms recorded from multiple surface electrodes following magnetic stimulation

Glerant

Mustfa²,

Man³

et al. 2006

European Respiratory Journal

View full text Add to dashboard Cite

show abstract

“…Although UMS is relatively specific with regards to Pdi,tw measurements, there is a degree of cross-stimulation such that a small EMG signal can be recorded from the contralateral hemidiaphragm. However, the PNCT recorded with UMS, particularly when using a high stimulating position [53], is close to that of electrical stimulation.…”

Section: Unilateral/bilateral Anterolateral Magnetic Phrenic Nerve Stmentioning

confidence: 53%

Magnetic stimulation for the measurement of respiratory and skeletal muscle function

Man¹

2004

European Respiratory Journal

117

View full text Add to dashboard Cite

Respiratory and skeletal muscle function is of interest in many areas of pulmonary and critical care medicine. The capacity of the respiratory muscle pump to respond to the load imposed by disease is the basis of an understanding of ventilatory failure. Over the last four decades, considerable progress has been made in quantifying the capacity of the respiratory muscles, in terms of strength, endurance and fatigue. With the development of magnetic stimulation, it has recently become possible to nonvolitionally assess the respiratory muscles in a clinically acceptable way. This is of particular interest in the investigation of patients receiving critical care, those with neuromuscular disease, and in children where volitional efforts are either not possible or likely to be sub-maximal. Furthermore, the adaptation of these techniques to quantify the strength of peripheral muscles, such as the quadriceps, has allowed the effects of muscle training or rehabilitation, uninfluenced by learning effect, to be assessed. This article focuses on the physiological basis of magnetic nerve stimulation, and reviews how the technique has been applied to measure muscle strength and fatigue, with particular emphasis upon the diaphragm. The translation of magnetic stimulation into a clinical tool is described, and how it may be of diagnostic, prognostic and therapeutic value in several areas of pulmonary medicine. In particular, the use of magnetic stimulation in neuromuscular disease, the intensive care setting, chronic obstructive pulmonary disease and paediatrics will be discussed. The nonvolitional assessment of skeletal musclesFor routine muscle strength measurements, the force generated from a maximum voluntary contraction (MVC) is often used. However volitional, effort-dependent manoeuvres for measuring strength are not always suitable for patients as the ability to perform a true MVC relies upon subject motivation and cooperation. This is particularly so in patients on intensive care units (ICU), children, patients with cognitive difficulties, and those patients prevented from performing a true MVC by pain (for example, following surgery). However, even in well-motivated subjects, sub-maximal muscle activation is common in routine clinical practice [1]. As volitional manoeuvres are influenced by a learning effect, the value of MVC is also limited in studies of training or rehabilitation. Consequently, there has been a need for nonvolitional methods to assess muscle strength. Skeletal muscle physiologySkeletal muscle is controlled by electrical impulses conducted by motor neurones that lead to the release of acetylcholine from the motor end plate, thus depolarising the muscle cell membrane. The force generated by muscle contraction is dependent upon a number of factors, including the number of muscle fibres stimulated, muscle length at the time of stimulation and the frequency of stimulation. The force-frequency curve of a muscle is of particular relevance in the understanding of nonvolitional techniques to asse...

show abstract

Inspiratory muscles do not limit maximal incremental exercise performance in healthy subjects

Romer

Miller

Haverkamp

et al. 2007

Respiratory Physiology & Neurobiology

View full text Add to dashboard Cite

We investigated whether the inspiratory muscles affect maximal incremental exercise performance using a placebo-controlled, crossover design. Six cyclists each performed 6 incremental exercise tests. For 3 trials, subjects exercised with proportional assist ventilation (PAV). For the remaining 3 trials, subjects underwent sham respiratory muscle unloading (placebo). Inspiratory muscle pressure (Pmus) was reduced with PAV (−35.9 ± 2.3% vs. placebo; P < 0.05). Furthermore, V̇O 2 and perceptions of dyspnea and limb discomfort at submaximal exercise intensities were significantly reduced with PAV. Peak workload, however, was not different between placebo and PAV (324 ± 4 vs. 326 ± 4 W; P > 0.05). Diaphragm fatigue (bilateral phrenic nerve stimulation) did not occur in placebo. In conclusion, substantially unloading the inspiratory muscles did not affect maximal incremental exercise performance. Therefore, our data do not support a role for either inspiratory muscle work or fatigue per se in the limitation of maximal incremental exercise performance.

show abstract

Diaphragm compound muscle action potential measured with magnetic stimulation and chest wall surface electrodes

Cited by 8 publications

References 19 publications

Diaphragm electromyograms recorded from multiple surface electrodes following magnetic stimulation

Diaphragm electromyograms recorded from multiple surface electrodes following magnetic stimulation

Magnetic stimulation for the measurement of respiratory and skeletal muscle function

Inspiratory muscles do not limit maximal incremental exercise performance in healthy subjects

Contact Info

Product

Resources

About