Objective: To compare the therapeutic effect of Shenmai injection (SM) and aminophylline (AP) on diaphragm fatigue in chronic obstructive pulmonary disease ( COPD ).Methods: Sixty-four COPD patients with respiratory failure and diaphragm fatigue were randomly divided into 2 groups. The SM group (n=33) was treated with oxygen inhalation

anti-infection agents

and SM injection (SM 40ml + 10% glucose 100ml). The AP group (n=31) was treated by the same comprehensive treatment but with AP 0. 25g instead of SM. The initial time of diaphragm fatigue disappearance

24 hrs maintaining effect and the arterial blood gas analysis were observed.Results: The effect in 30 min and maintaining effect in 24 hrs in SM group were better than those in AP group. In both groups

PaO2 increased and PaCO2 decreased.Conclusion: The therapeutic effect of SM on COPD patients with respiratory failure and diaphragm fatigue was better than those of AP.