Anterior magnetic phrenic nerve stimulation: laboratory and clinical evaluation

TY - JOUR

T1 - Anterior magnetic phrenic nerve stimulation: laboratory and clinical evaluation

AU - Polkey, M I

AU - Duguet, A

AU - Luo, Y

AU - Hughes, P D

AU - Hart, N

AU - Hamnegard, C H

AU - Green, M

AU - Similowski, T

AU - Moxham, J

PY - 2000

Y1 - 2000

N2 - 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 cmH(2)O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cmH(2)O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cmH(2)O. 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 (r(2) = 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 (r(2) = 0.60, p <0.0001) and the BAMPS-Tw Pdi (r(2) = 0.65, p <0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cmH(2)O 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.

AB - 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 cmH(2)O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cmH(2)O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cmH(2)O. 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 (r(2) = 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 (r(2) = 0.60, p <0.0001) and the BAMPS-Tw Pdi (r(2) = 0.65, p <0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cmH(2)O 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.

UR - http://www.scopus.com/inward/record.url?scp=0033851114&partnerID=8YFLogxK

U2 - 10.1007/s001340051319

DO - 10.1007/s001340051319

M3 - Article

VL - 26

SP - 1065

EP - 1075

JO - Intensive Care Medicine

JF - Intensive Care Medicine

IS - 8

ER -