Mouth pressure in response to magnetic stimulation of the phrenic nerves.

Hamnegåard, C H; Wragg, S; Kyroussis, D; Mills, Gary H.; Bake, Björn; Green, M; Moxham, John

doi:10.1136/thx.50.6.620

Cited by 85 publications

(68 citation statements)

References 14 publications

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“…In a preliminary study, we compared Poes,tw, considered as reference, to three noninvasive measurements of inspiratory pressure during magnetic stimulation and found that Pmo,tw during a gentle exhalation from FRC showed excellent agreement with Poes,tw. We think, therefore, like HAMNEGARD et al [8], that transmission of pressure to the upper airways is not hindered by glottis closure with this technique. The increased variability that we ob-served could have resulted from technical errors during the magnetic stimulation.…”

Section: Discussionmentioning

confidence: 95%

“…The Pmo,tw during gentle exhalation presented the best agreement with Poes,tw in all subjects. HAMNEGARD et al [8] also concluded that glottis closure can be avoided with this technique.…”

Section: Methodsmentioning

confidence: 99%

“…Twitch mouth pressure was measured during a gentle expiratory effort performed from FRC through the leak. This method was selected because, during phrenic nerve stimulation, glottis closure often prevents transmission of pressure changes from the thoracic cavity to the mouth [8][9][10]. Therefore, in a preliminary study, the pressure generated at the airway opening by cervical magnetic stimulation was measured using three different techniques.…”

Section: Methodsmentioning

confidence: 99%

“…Because it is better tolerated and easier to apply, cervical magnetic stimulation has now largely replaced electrical stimulation [6,7]. The measurement of twitch mouth pressure (Pmo,tw) during magnetic stimulation was recently reported as a reliable assessment of diaphragm strength [8].Thus, several noninvasive techniques are now available for assessing inspiratory muscle strength, based on volitional and nonvolitional manoeuvres. In order to use these new methods in clinical settings, it is necessary to characterize them in comparison with the established reference method.…”

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confidence: 99%

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confidence: 99%

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Reproducibility of twitch mouth pressure, sniff nasal inspiratory pressure, and maximal inspiratory pressure

Maillard¹,

Burdet²,

Melle³

et al. 1998

Eur Respir J

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The measurement of mouth pressure during a maximal inspiratory effort against a quasi occlusion (maximal inspiratory pressure (MIP)) is classically established as the standard for assessment of inspiratory muscle strength [1]. However, in addition to being closely dependent on subject collaboration, this manoeuvre is demanding and unpleasant. Thus, whilst high values of MIP exclude inspiratory muscle weakness, lower values are frequently difficult to interpret, reflecting either a true muscle weakness or a lack of motivation and co-ordination [2].A recent alternative noninvasive method consists of performing a short maximal sniff through one nostril while measuring nasal pressure through a plug occluding the contralateral nostril (sniff nasal inspiratory pressure (SNIP)) [3][4][5]. This natural manoeuvre is easier and less unpleasant than the static effort of MIP, but nevertheless depends on volitional muscle contraction. The need for a nonvolitional test, especially in situations where collaboration is totally lacking, has led to the development of phrenic nerve stimulation. Because it is better tolerated and easier to apply, cervical magnetic stimulation has now largely replaced electrical stimulation [6,7]. The measurement of twitch mouth pressure (Pmo,tw) during magnetic stimulation was recently reported as a reliable assessment of diaphragm strength [8].Thus, several noninvasive techniques are now available for assessing inspiratory muscle strength, based on volitional and nonvolitional manoeuvres. In order to use these new methods in clinical settings, it is necessary to characterize them in comparison with the established reference method. The aim of this study was to determine the reproducibility of SNIP and Pmo,tw during cervical magnetic stimulation and to compare them to classical MIP in a group of normal subjects. Materials and methods Study subjectsTen healthy volunteers (nine males, one female) were studied. Their characteristics were (mean±SD): age 28±7 Ten healthy subjects were studied at functional residual capacity in semirecumbent position. Cervical magnetic phrenic nerve stimulation was performed during gentle expiration against an occlusion incorporating a small leak. Constancy of stimulation was controlled by recording diaphragmatic electromyogram. Within and betweensession reproducibility of pressure were studied for Pmo,tw, SNIP, and MIP. The subjects were studied during a session of 10 manoeuvres repeated after 1 day and 1 month.The mean values were 16 cmH 2 O for Pmo,tw, 118 cmH 2 O for SNIP, and 115 cmH 2 O for MIP. For the three tests, the within subject variation was small in relation to between-subject variation, with the intraclass correlation coefficient ranging 0. We conclude that the within session reproducibility of the new tests twitch mouth pressure and sniff nasal inspiratory pressure is sufficient to be clinically useful. For sniff nasal inspiratory pressure, the between session reproducibility established after 1 day was maintained after 1 month. For twitch mouth pressure,...

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Section: Discussionmentioning

confidence: 95%

“…The Pmo,tw during gentle exhalation presented the best agreement with Poes,tw in all subjects. HAMNEGARD et al [8] also concluded that glottis closure can be avoided with this technique.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Reproducibility of twitch mouth pressure, sniff nasal inspiratory pressure, and maximal inspiratory pressure

Maillard¹,

Burdet²,

Melle³

et al. 1998

Eur Respir J

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show abstract

Functional magnetic stimulation of the respiratory muscles in dogs

1998

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This study assessed the ability of functional magnetic stimulation (FMS) to activate the respiratory muscles in dogs. With the animal supine, FMS of the phrenic nerves using a high‐speed magnetic stimulator was performed by placing a round magnetic coil (MC) at the carotid triangle. Following hyperventilation‐induced apnea, changes in volume (ΔV) and airway pressure (ΔP) against an occluded airway were determined. FMS of the phrenic nerves produced substantial inspired function (ΔV = 373 ± 20.5 mL and ΔP = −20 ± 2.0 cm H2O). After bilateral phrenectomies, maximal inspired ΔV (219 ± 12.2 mL) and ΔP (−10 ± 1.0 cm H2O) were produced when the MC was placed near the C6–C7 spinous processes, while maximal expired ΔV (−199 ± 22.5 mL) and ΔP (11 ± 2.3 cm H2O) were produced following stimulation near the T9–T10 spinous processes. We conclude: (1) FMS of either the phrenic or upper intercostal nerves results in inspired volume production; (2) FMS of the lower intercostal nerves generates expired volume production; and (3) FMS of the respiratory muscles may be a useful noninvasive tool for artificial ventilation and assisted cough in patients with spinal cord injuries or other neurological disorders. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1048–1057, 1998.

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Imaging of the Diaphragm Following Cardiac Surgery: Focus on Ultrasonographic Assessment

Rizza

Maranta

Cianfanelli

et al. 2023

J of Ultrasound Medicine

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Diaphragm dysfunction is a common complication following cardiac surgery. Its clinical impact is variable, ranging from the absence of symptoms to the acute respiratory failure. Post‐operative diaphragm dysfunction may negatively affect patients' prognosis delaying the weaning from the mechanical ventilation (MV), extending the time of hospitalization and increasing mortality. Ultrasonography is a valid tool to evaluate diaphragmatic impairment in different settings, like the Intensive Care Unit, to predict successful weaning from the MV, and the Cardiovascular Rehabilitation Unit, to stratify patients in terms of risk of functional recovery failure. The aim of this review is to describe the pathophysiology of post‐cardiac surgery diaphragm dysfunction, the techniques used for its diagnosis and the potential applications of diaphragm ultrasound.

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Mouth pressure in response to magnetic stimulation of the phrenic nerves.

Cited by 85 publications

References 14 publications

Reproducibility of twitch mouth pressure, sniff nasal inspiratory pressure, and maximal inspiratory pressure

Reproducibility of twitch mouth pressure, sniff nasal inspiratory pressure, and maximal inspiratory pressure

Functional magnetic stimulation of the respiratory muscles in dogs

Imaging of the Diaphragm Following Cardiac Surgery: Focus on Ultrasonographic Assessment

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