Thorax
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Diaphragm function can be assessed by electromyography of the diaphragm during electrical phrenic nerve stimulation (ES). Whether phrenic nerve conduction time (PNCT) and diaphragm electrical activity can be reliably measured from chest wall electrodes with ES is uncertain. ⋯ The results of this study show that lower chest wall electrodes only accurately measure PNCT when care is taken to avoid stimulating the brachial plexus. A false positive CMAP response to phrenic stimulation could be caused by inadvertent stimulation of the brachial plexus. This finding may further explain why the diaphragm CMAP recorded from chest wall electrodes can be unreliable with cervical magnetic stimulation during which brachial plexus activation occurs.