title: Validation of improved recording site to measure phrenic conduction from surface electrodes in humans.
abstract: 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.
authors.affiliation: UPRES EA 2397, Université Pierre et Marie Curie Paris VI, 75013 Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Verin
authors.forename: Christian
authors.initials: C
authors.lastname: Straus
authors.forename: Alexandre
authors.initials: A
authors.lastname: Demoule
authors.forename: Philippe
authors.initials: P
authors.lastname: Mialon
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Derenne
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
mesh_terms: D000328:Adult; D016477:Artifacts; D004558:Electric Stimulation; D004566:Electrodes; D004576:Electromyography; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008280:Magnetics; D008875:Middle Aged; D009333:Neck; D009431:Neural Conduction / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology*; D011930:Reaction Time