Potentiation of diaphragmatic twitch after voluntary contraction in normal subjects.

Wragg, S; Hamnegärd, C H; Road, Jeremy; Kyroussis, D; Moran, John M.; Green, M; Moxham, John

doi:10.1136/thx.49.12.1234

Cited by 101 publications

(77 citation statements)

References 22 publications

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“…The sessions always followed the same sequence in order to avoid the twitch potentiation phenomenon [11,12]. Firstly, Pmo,tw was measured during 10 stimulations performed at 30 s intervals.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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: Methodsmentioning

confidence: 99%

“…Before any measurement, the subjects rested quietly for at least 15 min in this position while the recording equipment was installed. During the study, the subjects were asked to breathe quietly, to remain on the bed and to avoid any physical effort in order to prevent the twitch potentiation phenomenon [11,12].…”

Section: Methodsmentioning

confidence: 99%

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

Maillard¹,

Burdet²,

Melle³

et al. 1998

Eur Respir J

View full text Add to dashboard Cite

show abstract

“…To preclude twitch potentiation, the subjects were first asked to breathe quietly and remain relaxed for 20 min [21]. BES, CMS and CxMS were performed at functional residual capacity (FRC), after airway occlusion, with the diaphragm relaxed.…”

Section: Methodsmentioning

confidence: 99%

Assessment of the voluntary activation of the diaphragm using cervical and cortical magnetic stimulation

Similowski

Duguet²,

Straus³

et al. 1996

Eur Respir J

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The twitch occlusion technique is a promising tool for use in assessing central drive to the diaphragm and determining maximal transdiaphragmatic pressure (Pdi) from submaximal efforts. Its clinical use is limited by difficulties inherent to bilateral electrical stimulation (BES) of the phrenic nerves. This study was designed to revisit the technique using cervical magnetic stimulation (CMS). In addition, the effects of a voluntary contraction on diaphragm response to magnetic stimulation of the cortex (CxMS) were studied.Seven volunteers aged 23-33 yrs were studied. Pdi was determined at relaxed functional residual capacity (FRC) in response to BES (Pdi,p-ES) and CMS (Pdi,p-CMS), and the effects of an increasing voluntary contraction (Pdi,vol) were assessed. The same procedure was applied to CxMS.Pdi,p-CMS at relaxed FRC was 27.5±2.2 cmH 2 O (mean±SEM), about 20% higher than Pdi,p-ES, as reported previously. Pdi,p-CMS linearly decreased with Pdi,vol, and six out of seven subjects were capable of producing voluntary contractions sufficient to extinguish the twitch. More complex patterns were observed with CxMS.Cervical magnetic stimulation provides diaphragmatic twitch occlusion data very similar to bilateral electrical phrenic stimulation. Magnetic stimulation, be it cervical or cortical, could probably be helpful for the assessment of central and peripheral mechanisms of diaphragmatic dysfunction in the clinical setting.

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“…The optimal stimulation point was identified and marked. To avoid the phenomenon of twitch potentiation [34] patients were asked to remain quiet for 20 minutes before measurements were taken.…”

Section: Twitch Transdiaphragmatic Pressure (Pditw)mentioning

confidence: 99%

Evaluation of the effectiveness of a home-based inspiratory muscle training programme in patients with chronic obstructive pulmonary disease using multiple inspiratory muscle tests

Nikoletou

Man

Mustfa

et al. 2015

Disability and Rehabilitation

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Purpose: To evaluate the effectiveness of a home-based Inspiratory Muscle Training (IMT) programme using multiple inspiratory muscle tests. group and trained with a threshold loading device at intensity >30% maximum inspiratory pressure (PImax) or < 15%PImax respectively for 7 weeks. Thirty nine patients (23M) completed the study. The following measures were assessed pre-and post-IMT: PImax, sniff inspiratory nasal pressure (SNIP), diaphragm contractility (Pdi,tw), incremental shuttle walk test (ISWT), respiratory muscle endurance (RME), chronic respiratory disease questionnaire (CRDQ), the hospital anxiety and depression scale (HADS) and the SF-36. Between group changes were assessed using one-way analysis of variance (ANOVA). Method Results

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Potentiation of diaphragmatic twitch after voluntary contraction in normal subjects.

Cited by 101 publications

References 22 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

Assessment of the voluntary activation of the diaphragm using cervical and cortical magnetic stimulation

Evaluation of the effectiveness of a home-based inspiratory muscle training programme in patients with chronic obstructive pulmonary disease using multiple inspiratory muscle tests

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