OBJECTIVE: Anterior magnetic stimulation (aMS) of the phrenic nerves is a new method for the assessment of diaphragm contractility that might have particular applications for the clinical assessment of critically ill patients who are commonly supine. DESIGN: We compared aMS with existing techniques for measurement of diaphragm weakness and fatigue in 10 normal subjects, 27 ambulant patients with suspected diaphragm weakness and 10 critically ill patients. SETTING: Laboratory and intensive care unit of two university hospitals. RESULTS: Although aMS was not demonstrably supramaximal in normal subjects, the mean value of twitch transdiaphragmatic pressure (Tw Pdi) obtained at 100% of stimulator output, 23.7 cmH2O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cmH2O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cmH2O. A fatiguing protocol produced a 20 % fall in aMS-Tw Pdi and a 19% fall in BAMPS-Tw Pdi; the fall in aMS-Tw Pdi correlated with the fall in BAMPS-Tw Pdi (r2 = 0.84, p = 0.03) indicating that aMS can detect diaphragm fatigue. In ambulant patients aMS agreed closely with existing measures of diaphragm strength. The maximal sniff Pdi correlated with both the aMS-Tw Pdi (r2 = 0.60, p < 0.0001) and the BAMPS-Tw Pdi (r2 = 0.65, p < 0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cmH2O less than BAMPS-Tw Pdi. In addition, aMS correctly identified diaphragm dysfunction in patients studied on the ICU. CONCLUSIONS: We conclude that aMS is of clinical value for the investigation of suspected diaphragm weakness.
OBJECTIVE: Anterior magnetic stimulation (aMS) of the phrenic nerves is a new method for the assessment of diaphragm contractility that might have particular applications for the clinical assessment of critically illpatients who are commonly supine. DESIGN: We compared aMS with existing techniques for measurement of diaphragm weakness and fatigue in 10 normal subjects, 27 ambulant patients with suspected diaphragm weakness and 10 critically illpatients. SETTING: Laboratory and intensive care unit of two university hospitals. RESULTS: Although aMS was not demonstrably supramaximal in normal subjects, the mean value of twitch transdiaphragmatic pressure (Tw Pdi) obtained at 100% of stimulator output, 23.7 cmH2O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cmH2O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cmH2O. A fatiguing protocol produced a 20 % fall in aMS-Tw Pdi and a 19% fall in BAMPS-Tw Pdi; the fall in aMS-Tw Pdi correlated with the fall in BAMPS-Tw Pdi (r2 = 0.84, p = 0.03) indicating that aMS can detect diaphragm fatigue. In ambulant patients aMS agreed closely with existing measures of diaphragm strength. The maximal sniff Pdi correlated with both the aMS-Tw Pdi (r2 = 0.60, p < 0.0001) and the BAMPS-Tw Pdi (r2 = 0.65, p < 0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cmH2O less than BAMPS-Tw Pdi. In addition, aMS correctly identified diaphragm dysfunction in patients studied on the ICU. CONCLUSIONS: We conclude that aMS is of clinical value for the investigation of suspected diaphragm weakness.
Authors: Daria Neyroud; John Temesi; Guillaume Y Millet; Samuel Verges; Nicola A Maffiuletti; Bengt Kayser; Nicolas Place Journal: Eur J Appl Physiol Date: 2015-02-15 Impact factor: 3.078
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Authors: Laurent Brochard; Greg S Martin; Lluis Blanch; Paolo Pelosi; F Javier Belda; Amal Jubran; Luciano Gattinoni; Jordi Mancebo; V Marco Ranieri; Jean-Christophe M Richard; Diederik Gommers; Antoine Vieillard-Baron; Antonio Pesenti; Samir Jaber; Ola Stenqvist; Jean-Louis Vincent Journal: Crit Care Date: 2012-12-12 Impact factor: 9.097