ObjectiveTo explore the effects of volume mechanical ventilation with different tidal on the diaphragm discharge in rats. MethodsTwenty-four SD rats were randomly divided into three groups, namely a high tidal volume group, a low tidal volume group, and a control group. The rats in the high tidal volume group and the low tidal volume group underwent volume controlled ventilation with tidal volume of 10 mL/kg and 5 mL/kg, respectively. The rats in the control group breath spontaneously after anesthetization. The EMGdi frequency, diaphragm discharge area, product of diaphragm discharge amplitude and diaphragm discharge rate (A×R) were measured every 2 hours to analyze the characteristics of diaphragm of rats under different duration of ventilation. ResultsCompared with the control group, there was no statistical difference of A×R in the high tidal volume group, but the frequency of the diaphragm discharge reduced and the discharge diaphragm area increased. When compared the low tidal volume group with the control group, only the A×R increased significantly. The transcutaneous oxygen saturation (SpO2) and end-tidal CO2 pressure (PetCO2) in the high tidal volume group decreased significantly compared to the control group while the other indexes had no difference. ConclusionsThe effects of mechanical ventilation with different tidal volume on the rat diaphragm discharge are different. The low tidal volume mechanical ventilation can excite the respiratory center and strengthen the diaphragm discharge with the stabilization of physiological index while the high tide volume inhibits diaphragm function and damages the oxygenation.