ObjectiveTo monitor the diaphragm function of mechanical ventilated patients in the intensive care unit. MethodsA prospective study was conducted on mechanical ventilation patients who had been evaluated by ventilation weaning screening test and planning to underwent spontaneous breathing trial between May 2013 and November 2013. A newly designed multi-function esophageal electrode was used to record the phrenic nerve conduction time (PNCT),diaphragm compound muscle action potential (CMAP) and twitch transdiaphragmatic pressure (TwPdi) elicited by bilateral anterolateral magnetic phrenic nerve stimulation. Results14 patients were recruited in this study. 1 case exited because of intolerance of repetitive magnetic stimulation,2 cases had no diaphragmatic electromyographic signals nor twitch signals,1 case had diaphragmatic electromyographic signal but could not be elicited by magnetic stimulation,1 case had no available TwPdi value with PNCT of 7.2 ms and CMAP of 1.26 mV. In the rest 9 cases,the PNCT,CMAP and TwPdi were (8.5±1.5)ms,(1.01±0.35)mV,(11.2±4.7)cm H2O,respectively. ConclusionNewly designed multi-function esophageal electrode catheter combined with bilateral anterolateral magnetic phrenic nerve stimulation can be used for non-volitional comprehensive assessment of diaphragm in critically ill patients,but not suitable for all subjects.