Cervical magnetic stimulation: a new painless method for bilateral phrenic nerve stimulation in conscious humans

Similowski, Thomas; Fleury, Bernard; Launois, Sandrine; Cathala, H.P.; Bouche, P; Derenne, J P

doi:10.1152/jappl.1989.67.4.1311

Cited by 298 publications

(236 citation statements)

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“…As noted by Luo et al (17), the PNCT values reported in earlier studies from our laboratory were longer (32,33). This is likely accounted for by the lower power of the stimulator used in these studies.…”

Section: Comparison With Previous Data From Our Laboratorymentioning

confidence: 51%

“…As in a previous study (35), the technique was slightly modified compared with its initial description (33,34) in that the subjects kept the neck in a neutral position instead of bending it forward. The handle of the coil was directed caudally and held either parallel to the vertebral column or at a 45°angle.…”

Section: Methodsmentioning

confidence: 99%

“…With CMS and UMS, the coactivation of extradiaphragmatic muscles is unavoidable (15,17,33). With ES, it can be difficult to dissociate the stimulation of the phrenic nerve from that of the brachial plexus (2,18).…”

Section: Signal Contaminationmentioning

confidence: 99%

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Validation of improved recording site to measure phrenic conduction from surface electrodes in humans

Vérin

Straus

Demoule

et al. 2002

Journal of Applied Physiology

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Phrenic nerve stimulation, electrical (ES) or from cervical magnetic stimulation (CMS), allows one to assess the diaphragm contractile properties and the conduction time of the phrenic nerve (PNCT) through recording of an electromyographic response, traditionally by using surface electrodes. Because of the coactivation of extradiaphragmatic muscles, signal contamination can jeopardize the determination of surface PNCTs. To address this, we compared PNCTs with ES and CMS from surface and needle diaphragm electrodes in five subjects (10 phrenic nerves). At a modified recording site, lower and more anterior than usual (lowest accessible intercostal space, costochondral junction) with electrodes 2 cm apart, surface and needle PNCTs were similar (CMS: 6.0 ± 0.25 ms surface vs. 6.2 ± 0.13 ms needle, not significant). Electrodes recording the activity of the most likely sources of signal contamination, i.e., the serratus anterior and pectoralis major, showed distinct responses from that of the diaphragm, their earlier occurrence strongly arguing against contamination. With ES and CMS, apparently uncontaminated signals could be consistently recorded from surface electrodes.

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Section: Comparison With Previous Data From Our Laboratorymentioning

confidence: 51%

Section: Methodsmentioning

confidence: 99%

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Validation of improved recording site to measure phrenic conduction from surface electrodes in humans

Vérin

Straus

Demoule

et al. 2002

Journal of Applied Physiology

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“…Compared with limb muscles, it is difficult to objectively assess fatigue of the diaphragm because both the muscle and the motor nerves are relatively inaccessible. Thus force development across the muscle (i.e., transdiaphragmatic pressure) is estimated by measuring the pressure difference between gastric and esophageal pressures induced by stimulation of both phrenic nerves (9,90,97,110). For the abdominal muscles, force output is estimated by measuring the gastric pressure response to magnetic stimulation of the thoracic nerve roots (61).…”

Section: Exercise-induced Respiratory Muscle Fatiguementioning

confidence: 99%

Exercise-induced respiratory muscle fatigue: implications for performance

Romer

Polkey²

2008

Journal of Applied Physiology

260

212

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Romer LM, Polkey MI. Exercise-induced respiratory muscle fatigue: implications for performance. J Appl Physiol 104: 879 -888, 2008. First published December 20, 2007 doi:10.1152/japplphysiol.01157.2007.-It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O 2 and CO2 transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exerciseinduced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles. respiratory muscles; exercise; diaphragm; abdominals; magnetic stimulation; metaboreflex THE PURPOSE OF THIS MINIREVIEW is to address the question of whether the respiratory demands of exercise contribute significantly toward exercise limitation, either directly through limitations of the respiratory muscle pump or indirectly through effects on limb blood flow and locomotor muscle fatigue. We describe the mechanical and metabolic costs of meeting the ventilatory requirements of exercise. We then ask whether the respiratory muscles fatigue with exercise, what factors contribute to any such fatigue, and what the implications of these factors are for exercise tolerance. Finally, we deal with the potential mechanisms by which respiratory muscle fatigue could compromise exercise tolerance and whether it is possible to overcome this potential respiratory limitation. Our review focuses on the healthy young adult exercising near sea level. However, we also consider special circumstances that determine the balance between metabolic demand and respiratory system capacity in the highly trained endurance ...

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“…These findings and the methodological problems described above prohibit definitive conclusions and warrant further investigation using new techniques and different methodology. Magnetic stimulation of the phrenic nerves is an accepted alternative to electrical stimulation and is a nonvolitional, simple and reproducible technique of assessing inspiratory muscle function that reduces the difficulties encountered with electrical stimulation [10].…”

mentioning

confidence: 99%

Diaphragmatic function after intense exercise in congestive heart failure patients

Kufel¹,

Pineda²,

Junega³

et al. 2002

Eur Respir J

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Respiratory muscle strength and endurance is reduced in patients with congestive heart failure, making these patients susceptible to diaphragmatic fatigue during exercise.In order to determine whether or not contractile fatigue of the diaphragm occurs in patients with congestive heart failure following intense exercise, twitch transdiaphragmatic pressures (twitch Ptdi) were measured during unpotentiated and potentiated cervical magnetic stimulation (CMS) of the phrenic nerves before and at intervals after cycle endurance exercise.Ten patients aged 65.7 ¡ 6.0 yrs (mean ¡ SD) with an ejection fraction of 31.2 ¡ 9.8% performed a constant-load symptom-limited exercise test at 60% of their peak work capacity. Twitch Ptdi at baseline were 15.9¡6.3 cmH 2 O (unpotentiated CMS) and 28.8¡ 10.7 cmH 2 O (potentiated CMS) and at 10 min postexercise were 16.4¡4.7 cmH 2 O (unpotentiated CMS) and 27.6¡10.1 cmH 2 O (potentiated CMS). One patient demonstrated a sustained fall in twitch Ptdi of o15%, considered potentially indicative of diaphragmatic fatigue.Contractile diaphragmatic fatigue is uncommon in untrained patients with congestive heart failure following high-intensity constant-workload cycle exercise. Therefore, diaphragmatic fatigue is an unlikely cause of exercise-limitation during activities of daily living in heart failure patients.

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Cervical magnetic stimulation: a new painless method for bilateral phrenic nerve stimulation in conscious humans

Cited by 298 publications

References 0 publications

Validation of improved recording site to measure phrenic conduction from surface electrodes in humans

Validation of improved recording site to measure phrenic conduction from surface electrodes in humans

Exercise-induced respiratory muscle fatigue: implications for performance

Diaphragmatic function after intense exercise in congestive heart failure patients

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