A microcomputer-based system developed for the automated analysis 01 the electromyogram (EMG) recorded from respiratory muscles in a variety of situations is described. In addition, an assessment of the perfmance of the sy.stem is presented, along with data relating intercostal EMG activity to ribcage movement in seated subjects. Studies were @formed on sixteen normal subjects -non smokers, mean (+ SD) age 31 (* 6) years, mean (* SD) mas.s 78 (& 8) kg -of which fifteen studies proved suitable for analysis. Each study lasted for a period of five minutes, during which time recordings of intercostal EMG, ribcage postero-anterior displacement (RCPA) and airflow were made. For every breath taken by each of the subjects, the peak integrated EMG activity (ib:MG,p,z,) was measured both by hand and by the automated system. The automated and manual measurements of iEMG,fl,k, which ranged from 0.0 to 91.3 pV, diffed by only -0.82f 3.34 ~.LV (mean* SD). The index iEMG,,_, and two additional indices of iRMG activity (iEMG,_, iEMG,,,,) were evaluated with respect to RCPA, a measure of overall respiratory activity. The indices of iRMG were observed to show an exponential depndence on RCPA,6,,,,,, the amplitude of ribcage motion. Following a log transformation to linearise the relationship, the correlation of each index with RCPA,,, was evaluated; iEMG,,,, and ilTMG<,, correlated similarly with RCPA,L, (no significant dzfference at 5 % level), but ZMG,,,,, was found to be a significantly d@rent (p < 0.001) and poorer correlate.
We conclude that the automated analysis of respiratory iMG as described in this paper can provide results showing consistency with manual measurement. The automated approarh show,s considerable benefit when substantial uolurnes of data are involved, or when it is desirable to perform analyses which are not amenable to manual methods.