Transcutaneous respiratory electromyographic monitoring

Abstract

The integrated diaphragm electromyogram (EMG) signal reflects function from the inspiratory centers to the neuromuscular junction. The feasibility and potential value of transcutaneous diaphragm electromyography (tcEMG) was confirmed in a group of infants using two prototype respiratory EMG monitors. Infants were monitored continuously for periods ranging from hours to days. One hundred were monitored for clinical reasons, looking for disordered respiratory behavior, while 47 were studied for technical/experimental reasons. Reliable measurements of diaphragm EMG activity were obtained, provided fully shielded electrode cables were used. Measurements in 28 ventilated infants and one adult confirmed that, unlike impedance and other non- electrophysiologic measures, tcEMG monitoring is not contaminated by ventilator-induced respiratory movements. The potential value of tcEMG monitoring in ventilated subjects is exemplified by illustrations of: 1) diaphragmatic inactivity from phrenic nerve injury, inadequate central drive, and neuromuscular block; 2) augmented expiratory muscle activity; and 3) progressive increase in inspiratory diaphragmatic activity in the presence of a tension pneumothorax. TcEMG monitoring should prove a worthwhile addition to the available noninvasive respiratory monitoring techniques.