Distinct neural-mechanical efficiency of costal and crural diaphragm during hypercapnia.

•In clinical practice, esophageal electromyography is assumed to represent neural drive and mechanical property of the entire diaphragm.•Esophageal electromyography records only the crural portion of the diaphragm.•Classic physiology suggests that the two distinct diaphragm segments, costal and crural, are functionally different.•During hypercapnic ventilation, costal diaphragm predominantly generated tidal volume, over crural diaphragm for the same neural activation.•Costal and crural diaphragm exhibit a significantly different neural-mechanical relationship.