Application of a cervical stimulating apparatus for bilateral
transcutaneous phrenic nerve stimulation.
Eastwood, Peter R., Janine A. Panizza, David R. Hillman, Kevin E.
Finucane.
Department of Pulmonary Physiology, Department of Human Movement,
Sir Charles Gairdner Hospital, Nedlands, Western Australia 6009,
University of Western Australia, Nedlands, Western Australia 6009
APStracts 2:0152A, 1995.
Transcutaneous bilateral phrenic nerve stimulation (tPNS) is
frequently used to assess diaphragmatic (di) function in humans.
Commonly, stimulation is performed with hand-held electrodes, however
these are unsuitable for studies requiring repeated PNS and where
recruitment of rib cage and neck muscles may shift the probes in
relation to the nerves. In this paper we describe the design of a
cervical neck brace and electrode probes which maintains stimulating
electrodes in constant position relative to the phrenic nerves and
facilitates studies requiring repeated maximal PNS. The effectiveness
of the apparatus was examined by (i) reviewing the reproducibility of
the transdiaphragmatic pressure (Pdi) response to 0.1 ms tPNS (PdiT)
at relaxed FRC in 4 subjects studied on 25+/-8 (mean+/-SD) occasions
(>/=24 hrs apart) over a 4 year period, and (ii) measuring peak-to
-peak amplitude of the left and right di compound muscle action
potentials (cMAP) (surface electrodes) during 2 prolonged studies
(38+/-9 mins) in each subject when tPNS was performed during repeated
submaximal and maximal inspiratory efforts. PdiT was reproducible in
each subject when measured repeatedly within a single study
(coefficient of variation (CV): 3.8+/-0.8%) and over separate days
(CV: 11.5+/-3.5%). The peak-to-peak amplitudes of the left and right
cMAPs were also reproducible (CV: 8.4+/-4.3 and 8.4+/-2.9%
respectively) and independent of the degree of effort. The apparatus
appears effective for the maintenance of maximal stimulation under
varied conditions for long periods providing reproducible
measurements of PdiT both within and between studies.
Received 21 August 1994; accepted in final form 31 March 1995.
APS Manuscript Number A886-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.