Diaphragmatic Compound Muscle Action Potentials Recorded From Over the Sternum and Lateral Chest Wall: a Comparative Study

Objectives: To report normative data for diaphragmatic compound muscle action potentials (DCMAPs) recorded from over the sternum and lateral chest wall (LCW). Method: The phrenic nerve of seventy-three healthy subjects was bilaterally stimulated at the posterior border of the sternocleidomastoid muscle. DCMAPs from over the sternum and LCW were recorded (inspiration/expiration). Results: Normative values of sternal and LCW DCMAPs were presented. Significant differences were found between sternal and LCW potentials in the mean latency, amplitude, and area (p<0.001). The duration did not differ between the two sites. Differences were found between inspiration and expiration, right and left sides, and men and women. Regression analysis showed a relation between latency of sternal and LCW potentials and age. Latency (LCW potentials) and amplitude and area (sternal/LCW potentials) were related to gender. Amplitude (LCW potentials/inspiration) and area (sternal potentials/inspiration) were related to chest circumference (p=0.023 and 0.013 respectively). Area (sternal potentials/expiration) was related to the BMI (p=0.019). Conclusions: Our normative values for sternal and LCW DCMAPs are provided. Notable differences in the DCMAPs parameters were detected between the two recording sites, inspiration and expiration, right and left, and men and women. Significance:The technique of phrenic nerve should be standardized.