Ejw. Maarsingh et al., Respiratory muscle activity measured with a noninvasive EMG technique: technical aspects and reproducibility, J APP PHYSL, 88(6), 2000, pp. 1955-1961
A new method is being developed to investigate airway obstruction in young
children by means of noninvasive electromyography (EMG) of diaphragmatic an
d intercostal muscles. The purpose of this study was to evaluate the reprod
ucibility of the EMG measurements. Eleven adults, 39 school children (20 he
althy, 19 asthmatic), and 16 preschool children were studied during tidal b
reathing on separate occasions: two for adults with a time interval of 3 wk
and three for children with time intervals of 1 and 24 h. Single electrode
s were placed on the second intercostal space left and right of the sternum
and at the height of the frontal and the dorsal diaphragm. Bipolar electro
de pairs were placed on the rectus abdominis muscle. A newly designed digit
al physiological amplifier without any analog filtering was used to measure
the EMG signals. Except for the average dorsal diaphragm EMG derivation in
healthy school children on the second occasion, a significant correlation
between the mean peak-to-peak inspiratory activity of average diaphragmatic
and intercostal EMG was found in the different age groups on the different
measurement occasions (P < 0.05). To assess the repeatability, we describe
d the agreement between the repeated measurements within the same subjects.
No significant differences were found between the measurements on the sepa
rate occasions. Our observations indicate that the EMG signals derived from
the diaphragm and intercostal muscles are, in different age groups with an
d without asthma, reproducible during tidal breathing.